Research on the Pore Distribution Characteristics and Strength Degradation of Cement-Based Materials under Sulfate Attack

Research on the Pore Distribution Characteristics and Strength Degradation of Cement-Based Materials under Sulfate Attack | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Research on the Pore Distribution Characteristics and Strength Degradation of Cement-Based Materials under Sulfate Attack Yuhang LI, Enze HAO, Xiumei ZHENG, Dali ZHANG, Wenbang ZHU, Ruiming LIU, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7526533/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Dec, 2025 Read the published version in Scientific Reports → Version 1 posted 17 You are reading this latest preprint version Abstract To investigate the influence of sulfate erosion on the performance of cement-based materials, this study designed mortar, concrete, and mortar-aggregate specimens with a water-to-cement ratio of 0.35. The study examined the changes in performance over 30 days, 60 days, 90 days, 120 days, and 150 days of sulfate erosion, and the findings showed that: as the duration of sulfate erosion increased, the mass change and compressive strength of cement-based materials generally showed an increasing trend first and then decreasing trend. The mass change of mortar, concrete, and mortar-aggregate specimens was 0.64%, 0.274%, and 0.16%, respectively, after 150 days of sulfate erosion. The compressive strength of mortar, concrete, and mortar-aggregate specimens decreased by 56.86%, 14.29%, and 19.34%, respectively, after 150 days of sulfate erosion. The porosity of mortar, concrete, and mortar-aggregate specimens showed that the porosity of mortar was greater than that of concrete, which was greater than that of mortar-aggregate specimens. The porosity of mortar-aggregate specimens showed a trend of decreasing first and then increasing after sulfate erosion. The porosity of mortar-aggregate specimens reached 12.57% after 30 days of sulfate erosion and 18.27% after 150 days of sulfate erosion. Physical sciences/Engineering Physical sciences/Materials science Sulfate Corrosion Cement-based Materials Porosity Quality change Compressive strength Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction Cement-based materials are the most extensively utilized construction materials globally, offering advantages such as ease of availability, cost-effectiveness, and excellent fire resistance. They find widespread application in residential buildings, bridges, roads, and various other structures [ 1 ]. Under standard conditions, cement-based materials exhibit commendable performance characteristics including compressive strength [ 2 – 4 ], deformation capacity [ 5 , 6 ], and durability [ 7 – 9 ]. However, due to their specific geographical locations or environmental conditions, structures situated in coastal regions [ 10 ] and saline-alkali areas are subjected to prolonged exposure to factors such as saline-alkali solutions and steam. Among these influences, sulfate erosion is one of the more prevalent degradation mechanisms [ 11 ]. In such scenarios, sulfate erosion can compromise several mechanical properties of cement-based materials; consequently, for relevant construction projects and marine engineering applications affected by sulfate attack on cement-based materials, the overall structural durability may be diminished. This reduction poses significant risks to both life safety and property. The sulfate attack on cement-based materials can be primarily categorized into physical and chemical reactions [ 12 – 14 ]. Physical reaction pertains to the crystallization of sulfates due to water evaporation and other factors during the sulfate erosion process [ 15 ]. Chemical reaction involves the interaction between sulfates and chemical constituents in cement-based materials, resulting in the formation of gypsum, ettringite, carburite, among others [ 16 , 17 ]. The degradation of concrete by sulfates is predominantly manifested through damage to hydrated calcium silicate gel, leading to a disruption of the original internal structural equilibrium of concrete [ 18 ]. Sulfate attacks typically present themselves in concrete as expansion and cracking phenomena [ 19 , 20 ]. When cracks develop, the accompanying sulfate solution is more prone to infiltrating the internal pores of concrete [ 21 ], adversely affecting key properties such as strength and durability post-sulfate attack. Under these circumstances, sulfate exposure diminishes the strength of cement-based materials [ 22 , 23 ]. Consequently, for construction projects and marine engineering endeavors situated in saline environments, sulfate-induced erosion poses a significant threat to overall structural durability by compromising cement-based material integrity—thereby endangering life safety and property. Currently, substantial advancements have been made regarding understanding how sulfates affect concrete erosion. Research conducted by Chindaprasirt et al. [ 24 ] and Gao et al. [ 25 ] examined damage characteristics under dry-wet cycling conditions—including ion diffusion patterns, volumetric expansion behaviors, weight loss metrics, alterations in mechanical properties—and confirmed that wet-dry cycling significantly influences concrete's damage progression compared with isolated sulfate environments. Meng et al. [ 26 ] investigated high-performance synthetic fiber-reinforced concrete subjected to sulfate erosion; their findings indicated superior crack resistance and freeze-thaw resilience relative to conventional concrete types. Tan et al. [ 27 ] analyzed load impacts on concrete columns through compression testing while discussing how sulfates influence these structures' performance attributes. Utilizing an extended numerical approach based on Ficks second law alongside second-order reaction dynamics principles,Wang et al.[ 28 ] concentrated on developing numerical analytical simulations along with ion diffusion models under sulfuric action aimed at predicting erosive processes within sodium sulfate solutions impacting concretes.In addition,some scholars have explored corresponding studies concerning crack morphology within concretes exposed to sulphate attacks,and multi-faceted environmental changes induced by sulphate under complex conditions[ 29 – 31 ]. However,much current analytical methodology examining dynamic effects exerted by sulphate upon concretes tends toward microscopic perspectives via SEM or XRD techniques[ 32 , 33 ]; systematic investigations focusing specifically upon clean pulp,mortar,and concretized responses remain relatively scarce. This paper aims at investigating pore modifications occurring within clean pulp,mortar,and concretized matrices subjected fully immersed into sulfonated mediums whilst quantitatively analyzing resultant pore transformations.By mitigating salt-induced deterioration across various forms comprising cements,this study seeks not only prolonging service lifespans but also minimizing disruptions arising from normal operational activities hindered due solely towards saliferous aggressions.Furthermore,it strives towards reducing waste generated through repetitive constructions necessitated owing damages inflicted onto existing infrastructures caused directly attributable back down salt-related erosions thereby contributing modestly towards sustainable development initiatives aimed ultimately lowering carbon dioxide emissions whilst promoting greener low-carbon methodologies throughout contemporary building practices. 2. Materials and Methods 2.1. Raw Materials The cement utilized is P·O 42.5R grade from Xinjiang Tianshan Cement Co., Ltd. The chemical composition is detailed in Table 1 . The mixing water employed is tap water sourced from Kashgar; the superplasticizer used is a liquid polycarboxylic acid-based superplasticizer. The fine aggregate consists of river sand with a fineness modulus of 2.51, classified as medium sand, while the coarse aggregate comprises gravel with particle sizes ranging from 5 to 20 mm and an apparent density of 2650 kg/m³. Table 1 Chemical composition of cement Ingredient mass fraction/% SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O Na 2 O Li 2 O Cement 20.12 5.75 3.26 63.44 0.98 2.71 0.49 0.73 2.13 2.2.Mix proportion In this experiment, three types of cement-based materials—namely clean pulp, mortar, and concrete—were systematically designed. Maintaining a consistent water-cement ratio, a specific proportion of sand was incorporated into the clean pulp to produce mortar, followed by the addition of a certain amount of stone to the mortar to yield concrete. This approach aimed to investigate the variations in different properties of these three cement-based materials post-erosion. The mix design adhered to the guidelines outlined in 'Masonry Mortar Mix Ratio Design Regulations' (JGJ/T 98-2011 of China) and 'Ordinary Concrete Mix Ratio Design Regulations' (JGJ55-2011 of China). The slump for concrete was controlled within the range of 150–180 mm. The mixing ratios for these cement-based materials are detailed in Table 2 . Table 2 Cement-based material mix ratio Number Water-binder ratio Cement-based materials amount of each material/(kg·m -3 ) Water Cement Sand Stone superplasticizer P 0.35 508 1451 0 0 2.9 M 0.35 219 627 1254 0 1.2 C 0.35 156 448 896 896 0.9 Note: P, M and C are respectively clean pulp, mortar and concrete 2.3.Test method 2.3.1 Sulfate Attack Regime In this experiment, clean pulp, mortar, and concrete cube samples with dimensions of 100 mm × 100 mm × 100 mm were prepared. Following a standard curing period of 28 days, the samples were placed in an oven at 80°C for drying over a duration of 48 hours. Once cooled, the specimens were immersed in a saturated solution of 5% Na 2 SO 4 for periods of 30 days, 60 days, 90 days, 120 days, and 150 days through complete submersion. After soaking, the specimens underwent another drying phase in an oven at 80°C for an additional period of 24 hours. The mass changes and compressive strengths of cement-based material specimens across each group at various ages were recorded; the average values from three test blocks per group were taken as final results.The press is shown in Fig. 1(a). 2.3.2 SEM Analysis Scanning Electron Microscopy (SEM) analysis was performed using a Phenom PROX machine to examine eroded specimens at different ages,As shown in Fig. 1(b). Specimens that had been eroded were fractured into flat sheets with diameters less than 5 mm and thicknesses approximately between 2–3 mm before being placed into a container filled with anhydrous ethanol to halt hydration processes; these sheets were subsequently baked in an oven set to maintain a temperature of 40°C for a duration of twenty-four hours. The dried sheets were then positioned on a loading platform and transferred to a vacuum gold sputtering apparatus for gold coating treatment prior to observation under electron microscopy equipment. 2.3.3 X-ray Diffraction Analysis An X-ray Diffraction (XRD) analysis was conducted utilizing instrumentation produced by Dandong Tongda Technology Co., Ltd., aimed at determining the phase composition within samples subjected to erosion over varying durations,as shown in Fig. 1(c). Eroded samples collected via core sampling techniques underwent immersion in anhydrous ethanol to cease hydration before being ground into powder form with particle sizes less than or equal to ten micrometers using mortar grinding methods; these powders were then analyzed using XRD equipment within scanning ranges from five degrees to ninety degrees employing continuous scanning protocols with step widths set at intervals of zero point zero two degrees. 2.3.4 Mercury Injection Analysis Mercury Intrusion Porosimetry (MIP) testing was executed utilizing the AutoPore IV9500 mercury intrusion porosimeter manufactured by McMurtry Equipment Co., Ltd.,as shown in Fig. 1(b). A sample measuring less than ten millimeters in diameter and approximately five millimeters thick was extracted from reserved specimens which had been soaked in anhydrous ethanol for forty-eight ± 0 .5 hours effectively terminating any ongoing hydration processes prior testing pore structure variations among specimens aged differently due to erosion effects; contact angle measurements registered at one hundred thirty degrees while aperture measurement ranged from zero point zero zero three micrometers up to three hundred sixty micrometers. 2.3.5 Low-field Nuclear Magnetic Analysis Nuclear Magnetic Resonance (NMR) Testing: The MesoMR12-060H-I high-precision magnetic resonance concrete microanalysis instrument produced by Suzhou NuoMai Analytical Instrument Co., Ltd. in China was used. Specimens measuring 40mm×40mm×4 mm were prepared, standard-cured for 90 days, and then placed in a vacuum water-retaining machine. After water retention was completed. The pore changes of specimens with different water-cement ratios were tested, with a pore size measurement range of 0.00002 to 200 µm. 3. Results and analysis 3.1 Mass change after sulfate attack Figure 2 illustrates the changes in mass of cement-based materials subjected to sulfate attack over a period of 150 days. As depicted in the figure, the mass variations of clean pulp, mortar, and concrete specimens generally exhibit an initial increase followed by a subsequent decrease. At 60 days of exposure, both clean pulp and concrete reached their maximum mass change values, with increases of 1.22% and 0.73%, respectively. By day 150, the corresponding mass losses were recorded at 0.64% for clean pulp and 0.16% for concrete. The mortar specimen experienced its peak mass change at day 90 with an increase of 0.77%, while at day 150 it showed a further increase of only 0.274%. This phenomenon can be attributed to the reaction between sulfate ions and gelling materials that produces erosion products such as gypsum and ettringite, thereby enhancing the specimen's mass initially; however, as erosion progresses over time, these products accumulate leading to expansion and cracking within the specimen which ultimately results in material loss. Following sulfate-induced erosion, the trend observed in mortar is analogous to that seen in clean mortar samples. The incorporation of fine aggregates stabilizes pore distribution within the mortar matrix; consequently, this leads to a reduced relative change in quality post-erosion with more gradual fluctuations compared to other specimens. Initially increasing with prolonged exposure time due to erosion effects on structural integrity—mortar begins experiencing reductions in quality thereafter as degradation sets in more prominently over time than previously noted trends suggest when coarse aggregates are included within concrete mixtures; thus resulting faster alterations during early stages owing primarily due interfacial transition zones formed from coarse aggregate addition—these zones represent weak links susceptible towards sulfate attacks [ 34 , 35 ]. Therefore relative changes regarding quality among concrete specimens are significantly influenced by these transitional interfaces where initial growth rates surpass those observed amongst mortars alongside earlier peaks occurring therein." 3.2 The change of compressive strength after sulfate attack Figure 3 illustrates the variation in compressive strength over a period of 150 days under sulfate attack. As depicted in the figure, the compressive strength of the unaltered pulp specimen exhibited a general declining trend, with an initial value of 54.11 MPa prior to erosion and reaching a minimum of 23.34 MPa after 150 days of exposure. Conversely, both mortar and concrete specimens initially demonstrated a gradual increase in compressive strength followed by a decline. The maximum compressive strength for mortar was recorded at 55.67 MPa after 90 days of erosion, while it decreased to a minimum value of 47.71 MPa at the end of the 150-day period. For concrete specimens, peak compressive strength was observed at 59.15 MPa after being eroded for 60 days; however, this diminished to a minimum value of 45.20 MPa following complete erosion over the same duration. This phenomenon can be attributed to early-stage erosion where sulfate ions infiltrate cement-based materials and react with calcium hydroxide from cement hydration products to form gypsum; subsequently, gypsum interacts with aluminum-containing hydration products leading to ettringite formation. The resultant gypsum and ettringite progressively fill internal pores within cement-based material specimens, thereby contributing to an incremental rise in their overall strength [ 36 ]. During this phase, enhancements in compressive strength are closely linked to alterations in porosity within these materials' structures. In contrast, during mid-to-late stages of erosion, expansive forces compromise pore integrity within cement-based materials resulting in reduced structural strength. 3.3 XRD phase analysis To understand the erosion products after sulfate attack, X-ray diffraction analysis was conducted on mortar specimens at 0 days, 30 days, 60 days, 90 days, 120 days, and 150 days of erosion. As shown in Fig. 4 , at 0 days, the main phases were silica, calcium oxide, calcium hydroxide, and calcium silicate, etc. After sulfate attack, the diffraction peak of calcium hydroxide remained, indicating that the hydration of cement had not stopped. At 30 days of erosion, ettringite was added as the main phase, suggesting that the sulfate attack was mainly due to the chemical reaction between sulfate ions and the hydration products of cement, resulting in the formation of ettringite and causing damage to the cement-based material [ 37 ]. With the continuous increase of the erosion age, the types of products formed during the erosion process did not change. 3.4 Microscopic morphology analysis by scanning electron microscopy Figure 5 shows the SEM images of mortar specimens subjected to sulfate attack at 0d, 30d, 60d, 90d, 120d and 150d. It can be seen from the figure that the microstructure inside the specimens varies significantly at different attack ages. As shown in (a), the internal microstructure of the specimen at 0d of attack is relatively smooth, indicating good cement hydration. As shown in (b), at 30d of attack, the internal microstructure is different from the smooth surface of the unattacked specimen, with short columnar products generated inside and erosion products beginning to adhere to the surface. The pore diameter starts to decrease, indicating that the erosion products have been formed and are beginning to fill the pores inside the specimen. As shown in (c), at 60d of attack, there are a few pores and microcracks, indicating some damage. This is due to the increasing amount of erosion products, which causes microcracks in the specimen. As shown in (d), at 90d of attack, the internal pore surface has become uneven, with gypsum and ettringite covering the originally smooth surface and further filling the pores. At this point, the strength of the mortar reaches its peak. The filling effect of the internal products on the pores is greater than the effect of the decomposition of the cementitious materials on the strength, so the macroscopic manifestation is an increase in compressive strength and mass change. As shown in (e), at 120d of attack, a small amount of ettringite begins to form inside the specimen. As shown in (f), at 150d of attack, the internal morphology of the specimen is significantly different from the initial state. Due to the continuous accumulation of erosion products, a large number of needle-like ettringite products appear inside, causing the internal morphology to become honeycomb-like. The macroscopic manifestation is a decrease in compressive strength and mass change. 3.5 Pore changes after sulfate attack based on mercury injection technique Figure 6 illustrates the pore size distribution curve of clean slurry, mortar, and concrete after 28 days of curing. The figure indicates that, under a constant water-cement ratio, the cement clean slurry exhibits the largest pore distribution and porosity at 26.38%. Upon incorporating sand, there is a significant reduction in pores smaller than 100 nm and larger than 10,000 nm; consequently, the pore size distribution becomes more uniform and porosity decreases to 13.58%. With the addition of coarse aggregate, heterogeneity within the cement-based material increases, leading to an increase in harmful pores exceeding 10,000 nm compared to mortar; thus raising porosity to 20.06%. Figure 7 presents a diagram depicting changes in pore structure and accumulation for clean pulp, mortar, and concrete over a curing period of 28 days. According to Academician Wu Zhongwei [ 38 , 39 ], internal pore diameters in cement-based materials are classified into several categories: Level One: harmless pores (0 nm − 20 nm); Level Two: less damaging pores (20 nm − 50 nm); Level Three: harmful pores (50 nm -200 nm); Level Four: multiple holes (greater than 200nm). As illustrated in the figure, proportions of harmless holes, less harmful holes, harmful holes and multi-harmful holes in clean pulp are recorded as follows: zero percent for harmless holes; 6.06% for less harmful; 8.07% for harmful; and an overwhelming majority of 85.86% for multi-harmful holes—indicating a predominance of detrimental structures due to fine cement particles being susceptible to environmental temperature fluctuations which lead them to shrink or expand.In contrast with mortar's composition where proportions stand at: harmless holes (18.02%), less harmful (39.48%), harmful (15.66%) and multi-harmful (26.82%), it is evident that mixing sand significantly enhances both harmless hole ratios while reducing those categorized as multi-harmful due primarily to volume stability provided by fine aggregates which mitigate overall shrinkage within cement-based materials—resulting in predominant volumes found within the diameter range of approximately ten-to-one hundred nanometers.For concrete samples analyzed post-coarse aggregate incorporation reveal proportions as follows: harmless holes at just above two percent (1.82%), slightly damaged at eight point five four percent (8 .54%), harmfully affected at seventeen point twenty-nine percent(17 .29%)and predominantly multiharmed structures comprising seventy-two point thirty-four percent(72 .34%). This shift reflects how stone filling complicates pore pathways while amplifying larger voids particularly around interface transition zones." Figure 8 shows the pore size distribution curves of mortar for sulfate attack at 0d, 30d, 90d, and 150d. From the figure, it can be seen that sulfate attack has a significant impact on the pore size range of 10 nm to 10,000 nm in the mortar. At 30d of sulfate attack, the mercury penetration in the 10 nm-100 nm range and the range greater than 10,000 nm is less than that of 0d, while the mercury penetration in the 100 nm-10,000 nm range is greater than that of 0d. The porosity rate decreases from 13.58% at 0d to 12.57% at 30d of sulfate attack. This is because in the early stage of sulfate attack, the sulfate will react with the hydraulic binder materials to generate expansive products to fill the pores, resulting in a decrease in porosity rate. At 90d of sulfate attack, the mercury penetration in the 0 nm-75 nm range and the range greater than 100,000 nm is less than that of 30d, while the mercury penetration in the 75 nm-100,000 nm range is greater than that of 30d. The porosity rate increases from 12.57% at 30d to 14.17% at 90d of sulfate attack. This is because in the middle and late stages of sulfate attack, as the reaction proceeds and the products accumulate, the generated expansive force increases, and when the expansive force exceeds the tensile strength of the pore limit, the internal structure of the specimen will be destroyed, causing the pores to enlarge. At 150d of sulfate attack, the mercury penetration in the range greater than 10,000 nm reaches the maximum, and the porosity rate increases to 18.27%. This is because in the late stage of sulfate attack, the sulfate products will continue to accumulate, and the expansive force will become Figure 9 illustrates the changes in pore structure and accumulation patterns of mortar subjected to sulfate erosion over periods of 0, 30, 90, and 150 days. The diagram indicates that as the duration of erosion increases, the proportion of multi-damage pores initially decreases before subsequently rising. In uneroded mortar, the proportions of harmless pores, slightly damaged pores, harmful pores, and multiple damage pores were recorded at 18.02%, 39.48%, 15.66%, and 26.82%, respectively. After a period of 30 days under erosive conditions, these proportions shifted to 10.86% for harmless pores, 44.43% for slightly damaged ones, while harmful and multi-harmful pore percentages were noted at 15.07% and 29.62%. This change reflects a decrease in both harmless and harmful pore ratios alongside an increase in less harmful and multi-harmful categories due to expansion products generated by sulfate attack filling previously harmful voids—effectively reducing their diameter into less damaging classifications. Following an additional erosion period leading up to day-90 results showed proportions at: harmless (16.49%), slightly damaged (29.72%), harmful (14.18%), with multiple damage increasing significantly to reach a total of (39.60%). Here again we observe a decline in both slight damage and harm categories while there is an uptick in both harmlessness as well as multiple damages observed post-erosion phase extending through day-150 where final measurements indicated: harmless holes at just (0 .59%), slightly harmed at (7 .41%), with significant rises seen within harmful holes reaching (19 .59%) along with more severely affected holes escalating dramatically to account for (72 .40%). Notably here too was evident reduction among benign or mildly impacted voids contrasted against notable increases within detrimental classifications; this phenomenon can be attributed primarily towards late-stage erosional processes wherein internal porosity becomes filled by resultant products yet continues generating further expansive forces which exacerbate crack propagation throughout mortar matrices thereby amplifying overall porosity levels [ 40 ]. 3.6 Pore changes after sulfate attack based on low-field nuclear magnetic resonance technology The transverse relaxation time T2 spectrum of nuclear magnetic resonance reflects the distribution of pore sizes in cement-based materials. The shorter the transverse relaxation time T2, the smaller the pore radius; the longer the transverse relaxation time T2, the larger the pore radius. The position of each peak in the T2 spectrum distribution curve is related to the pore size, and the size of the integral area of each peak reflects the change in the number of internal pores in cement-based materials [ 41 ]. Figure 10 shows the nuclear magnetic resonance analysis diagrams of P, M, and C after 28 days of curing. From Figure (a), it can be seen that the nuclear magnetic resonance T2 spectra of P and M mainly present a "main peak" structure. The main peaks are all distributed at shorter transverse relaxation times, and the signal intensity shows P > M, indicating that the number of small pores inside P and M accounts for a larger proportion, with only a small part being large pores. The transverse relaxation time T2 of P is between 0.017 and 3217.642 ms, and that of M is between 0.022 and 4824.108 ms. The nuclear magnetic resonance T2 spectrum of C mainly presents a "main and secondary peak" structure. The main peaks are all distributed at shorter transverse relaxation times, and their signal intensity and the integral area under the distribution curve are significantly larger than those of the secondary peaks, indicating that the number of small pores inside the concrete accounts for a larger proportion, with only a small part being large pores. The transverse relaxation time T2 of C is between 0.02 and 2967.3 ms. It can be clearly seen from Figure (a) that the porosity of the paste specimens is relatively large, and with the addition of sand and gravel, the internal bonding force of the matrix is increased, and the fine and coarse aggregates are improved, thereby improving the pore structure, and the number of pores in the cement-based materials gradually decreases, and the porosity gradually decreases. As shown in Fig. 10(b) and (c), the pore change accumulation diagrams of the paste, mortar, and concrete are presented. The proportion of various types of pores in P, M, and C is statistically described based on the nuclear magnetic resonance T2 spectrum distribution curve. It can be seen from the figure that the porosity of P is 24.93%, with the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores being 85.86%, 9.16%, 2.5%, and 2.46% respectively; the porosity of M is 8.88%, with the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores being 71.14%, 10%, 6.23%, and 12.62% respectively; the porosity of C is 11%, with the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores being 61.5%, 4.12%, 4.49%, and 29.87% respectively. For the paste, mortar, and concrete specimens, the porosity continuously decreases with the addition of sand, and increases with the addition of sand and gravel. The proportions of harmless pores, slightly harmful pores, and harmful pores decrease, while the proportion of highly harmful pores increases. Analysis of the reasons: The addition of sand and gravel improves the pore structure of the material to a certain extent. As aggregates, sand and gravel can fill some pores, reducing the formation of harmful and highly harmful pores, thereby increasing the density and overall performance of the material. However, after adding gravel to the mortar, although the internal bonding force of the matrix is further enhanced, more interface transition zones are introduced, which are often weak and prone to become concentrated areas of pores and micro-cracks, resulting in an increase in porosity, especially a significant increase in the proportion of highly harmful pores. In addition, the pore structure of the gravel itself may also affect the overall porosity. Figure 10 The P, M and C magnetic resonance imaging analysis diagrams after 28 days of maintenance;(a)PMCT2 spectrum analysis curve(b) Pore distribution (c) pore change Figure 11 shows the NMR analysis of M after 150 days of sulfate attack. As can be seen from Figure (a), the NMR T2 spectrum of M before erosion mainly presents a "main peak" structure. The main peaks are all distributed at the shorter transverse relaxation time, with T2 ranging from 0.022 to 4824.108 ms, indicating that the number of small pores inside M accounts for a large proportion, while only a small part are large pores. After erosion, the NMR T2 spectrum of M mainly presents a "main and secondary peak" structure. The main peaks are all distributed at the shorter transverse relaxation time, and the signal intensity and the area under the distribution curve of the main peaks are significantly greater than those of the secondary peaks, indicating that the pore structure inside the mortar has undergone significant changes after sulfate attack. The transverse relaxation time T2 of M after erosion ranges from 0.002 to 10000 ms. As shown in Figs. 11(b) and (c), they are the pore change accumulation diagrams of the mortar after sulfate attack. The proportion of pores in the mortar before and after erosion is statistically described in combination with the NMR T2 spectrum distribution curve. It can be seen from the figure that the porosity of M before erosion is 8.88%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 71.14%, 10%, 6.23%, and 12.62% respectively. After 30 days of erosion, the porosity is 7.60%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 77.93%, 3.91%, 4.13%, and 14% respectively. The proportions of harmless pores and highly harmful pores increase, while the proportions of slightly harmful pores and harmful pores decrease. After 90 days of erosion, the porosity is 6.91%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 83.35%, 2.85%, 2.85%, and 10.93% respectively. The proportion of harmless pores increases, while the proportions of slightly harmful pores, harmful pores, and highly harmful pores decrease. After 150 days of erosion, the porosity is 14.42%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 78.58%, 3.62%, 3.93%, and 13.86% respectively. The proportions of harmless pores and slightly harmful pores decrease, while the proportions of harmful pores and highly harmful pores increase. This is because, in the initial stage of erosion, sulfate will react chemically with the internal substances of the cement-based material to form gypsum and other substances, filling the internal pores of the specimen, reducing the porosity and the proportions of harmful pores and highly harmful pores. In the later stage of erosion, as the chemical reaction continues, the products increase. When the volume of the products reaches a certain amount, it will cause the specimen to crack, increasing the proportions of harmful pores and highly harmful pores. The pore changes of mortar specimens were analyzed by combining the pressure mercury method and nuclear magnetic resonance technology. It was found that there were certain differences in the porosity measured by the two methods, but the changing trends were consistent. This was mainly due to the different sample sizes tested by the two methods, which led to minor differences in the measurement results. The pressure mercury method is usually suitable for smaller volume samples and can more accurately reflect the local pore structure, while nuclear magnetic resonance technology is suitable for larger volume samples and can provide more comprehensive pore distribution information. Despite the differences, both methods indicated that with the increase of erosion age, the porosity of cement-based materials first decreased and then increased. By comprehensively analyzing the test results of the two methods, the influence mechanism of pore structure on the performance of cement-based materials can be better understood, providing important references for optimizing material ratios and improving material performance. 4. Conclusion This study focuses on cement-based materials, examining the impact of sulfate attack on the properties of clean pulp, mortar, and concrete. The following conclusions can be drawn: (1) The quality variations in clean pulp, mortar, and concrete initially increase and subsequently decrease with prolonged sulfate exposure. Clean pulp and concrete reach their peak values at 60 days of exposure, increasing by 1.22% and 0.73%, respectively; whereas mortar attains its maximum value at 90 days of exposure with an increase of 0.77%. (2) The compressive strength of clean slurry exhibits a decreasing trend as erosion age increases, reaching a minimum value of 23.34 MPa. In contrast, the compressive strengths of both mortar and concrete show an initial increase followed by a decline; after 150 days of erosion, the compressive strength for mortar decreases by 14.29%, while that for concrete declines by 19.34%. (3) Among clean slurry, mortar, and concrete with identical water-cement ratios, the porosity is highest in clean slurry compared to both concrete and mortar. Following sulfate erosion treatment, the porosity in mortar first decreases before increasing again—showing a reduction of 1.01% at day 30 but an increase of 5.7% at day 150. (4) The pore changes of cement-based materials were analyzed by combining the pressure mercury method and nuclear magnetic resonance technology. It was found that there were certain differences in the porosity measured by the two methods, but the changing trends were consistent. Declarations Author contributions Yuhang Li: Writing–review & editing, Conceptualization, Methodology, Supervision, Data curation, Project administration, Funding acquisition. Enze Hao: Writing–review & editing, Supervision, Conceptualization, Formal analysis, Validation. Xiumei Zheng: Writing–review & editing, Conceptualization, Software, Formal analysis. Dali Zhang: Conceptualization, Methodology, Data curation, Software, Validation. Wenbang Zhu: Writing–review & editing, Supervision, Project administration, Validation. Ruiming Liu: Resources, Validation. Xinjie Wang: Validation. Yali Cao: Resources, Validation. Chaochao Sun: Resources. Debo He: Resources. Chao Yang: Resources. Gang Li: Validation. Funding ： This work was financially supported by the 2025 Xinjiang Uygur Autonomous Region Natural Science Foundation project (2025D01A05), Kashi University-level project (（2024）2930、（2024）2926),China National University Student Innovation & Entrepreneurship Development Program(202510763010,202510763149).Liaoning Provincial Institute of Construction Science Co., Ltd.2024 Key Research Project of Liaoning Province (2024JH2/102400016). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study Data Availability Statement: All data are available upon request from the corresponding author. Conflicts of Interest: The authors declare no conflict of interest References Yao, A., Xu, J. & Xia, W. An Experimental Study on Mechanical Properties for the Static and Dynamic Compression of Concrete Eroded by Sulfate Solution[J]. Materials 14 (18), 5387 (2021). Wu, H. et al. Erosion resistance behavior of recycled plastic concrete in sodium sulfate solution[J]. Constr. Build. Mater. 324 , 126630 (2022). Cheng, H. et al. Compressive strength assessment of sulfate-attacked concrete by using sulfate ions distributions[J]. Constr. Build. Mater. 293 , 123550 (2021). Liu, X. et al. Mechanical relationship between compressive strength and sulfate erosion depth of basalt fiber reinforced concrete[J]. Constr. Build. Mater. 411 , 134412 (2024). Khosravani, M. R. & Weinberg, K. A review on split Hopkinson bar experiments on the dynamic characterisation of concrete[J]. Constr. Build. Mater. 190 , 1264–1283 (2018). Lacidogna, G. et al. Multi-technique damage monitoring of concrete beams: acoustic emission, digital image correlation, dynamic identification[J]. Constr. Build. Mater. 242 , 118114 (2020). Li, H. et al. Durability investigation of fractured coal-gasified ash slag concrete eroded by sulfate and chlorine salts[J]. Case Stud. Constr. Mater. 20 , e02745 (2024). Zhang, A. et al. Durability effect of nano-SiO2/Al2O3 on cement mortar subjected to sulfate attack under different environments[J]. J. Building Eng. 64 , 105642 (2023). Ali, B., Gulzar, M. A. & Raza, A. Effect of sulfate activation of fly ash on mechanical and durability properties of recycled aggregate concrete[J]. Constr. Build. Mater. 277 , 122329 (2021). Tang, S. W. et al. Recent durability studies on concrete structure[J]. Cem. Concr. Res. 78 , 143–154 (2015). Chen, F. et al. Deterioration mechanism of plain and blended cement mortars partially exposed to sulfate attack[J]. Constr. Build. Mater. 154 , 849–856 (2017). Rozière, E. et al. Durability of concrete exposed to leaching and external sulphate attacks[J]. Cem. Concr. Res. 39 (12), 1188–1198 (2009). Aye, T. & Oguchi, C. T. Resistance of plain and blended cement mortars exposed to severe sulfate attacks[J]. Constr. Build. Mater. 25 (6), 2988–2996 (2011). He, P. et al. Effect of ion chelator on microstructure and properties of cement-based materials under sulfate dry-wet cycle attack[J]. Constr. Build. Mater. 257 , 119527 (2020). Liu, Z., Deng, D. & De Schutter, G. Does concrete suffer sulfate salt weathering?[J]. Constr. Build. Mater. 66 , 692–701 (2014). Atahan, H. N. & Arslan, K. M. Improved durability of cement mortars exposed to external sulfate attack: The role of nano & micro additives[J]. Sustainable cities Soc. 22 , 40–48 (2016). Chen, Y. et al. Resistance of concrete against combined attack of chloride and sulfate under drying–wetting cycles[J]. Constr. Build. Mater. 106 , 650–658 (2016). He, R. et al. 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Experimental investigation on the durability performances of concrete using cathode ray tube glass as fine aggregate under chloride ion penetration or sulfate attack[J]. Constr. Build. Mater. 163 , 634–642 (2018). Chindaprasirt, P. et al. Effects of sulfate attack under wet and dry cycles on strength and durability of Cement-Stablized laterite[J]. Constr. Build. Mater. 365 , 129968 (2023). Gao, J. et al. Durability of concrete exposed to sulfate attack under flexural loading and drying–wetting cycles[J]. Constr. Build. Mater. 39 , 33–38 (2013). Meng, C. et al. Experimental research on durability of high-performance synthetic fibers reinforced concrete: Resistance to sulfate attack and freezing-thawing[J]. Constr. Build. Mater. 262 , 120055 (2020). Tan, Y. et al. Study on the micro-crack evolution of concrete subjected to stress corrosion and magnesium sulfate[J]. Constr. Build. Mater. 141 , 453–460 (2017). Wang, H. et al. Numerical simulation of external sulphate attack in concrete considering coupled chemo-diffusion-mechanical effect[J]. Constr. Build. Mater. 292 , 123325 (2021). Zhang, X. et al. Experimental investigation on the fracture properties of concrete under different exposure conditions[J]. Theoret. Appl. Fract. Mech. 127 , 104073 (2023). Liu, D. et al. A review of concrete properties under the combined effect of fatigue and corrosion from a material perspective[J]. Constr. Build. Mater. 369 , 130489 (2023). Hou, W., He, F. & Liu, Z. Characterization methods for sulfate ions diffusion coefficient in calcium sulphoaluminate mortar based on AC impedance spectroscopy[J]. Constr. Build. Mater. 289 , 123169 (2021). He, P. et al. Effect of ion chelator on microstructure and properties of cement-based materials under sulfate dry-wet cycle attack[J]. Constr. Build. Mater. 257 , 119527 (2020). Wang, K. et al. Influence of dry-wet ratio on properties and microstructure of concrete under sulfate attack[J]. Constr. Build. Mater. 263 , 120635 (2020). Chen, X. et al. A chemical-transport-mechanics numerical model for concrete under sulfate attack[J]. Materials 14 (24), 7710 (2021). Lu, D. et al. Mitigating sulfate ions migration in concrete: A targeted approach to address recycled concrete aggregate's impact[J]. J. Clean. Prod. 442 , 141135 (2024). Han, S. et al. Sulfate resistance of eco-friendly and sulfate-resistant concrete using seawater sea-sand and high-ferrite Portland cement[J]. Constr. Build. Mater. 305 , 124753 (2021). Shi, X. et al. A comprehensive investigation on sulphate resistance of geopolymer recycled concrete: Macro and micro properties[J]. Constr. Build. Mater. 403 , 133052 (2023). Wu, Z. W. & Lian, H. Z. H. Performance concrete.Beijing: China Railway, (1999). .(in Chinese). Li, Y. et al. Study on chloride attack resistance of concrete with lithium slag content[J]. J. Building Eng. , : 110723. (2024). Shi, C. & Yang, Y. Unveiling the Effects of Quicklime on the Properties of Sulfoaluminate Cement–Ordinary Portland Cement–Mineral Admixture Repairing Composites and Their Sulphate Resistance[J]. Materials 16 (11), 4026 (2023). Hao, E. et al. Research on the mechanism of pore structure on water transportation in cement-based materials[J]. PLoS One . 20 (7), e0327659 (2025). Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7526533","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":514947298,"identity":"6c9651fc-5575-42da-b5a6-b29f749d2996","order_by":0,"name":"Yuhang LI","email":"","orcid":"","institution":"kashi university","correspondingAuthor":false,"prefix":"","firstName":"Yuhang","middleName":"","lastName":"LI","suffix":""},{"id":514947299,"identity":"605ecdaf-6b7c-4b8e-aa03-48b7d10e77b6","order_by":1,"name":"Enze HAO","email":"","orcid":"","institution":"kashi 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10:18:49","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":594731,"visible":true,"origin":"","legend":"\u003cp\u003eTest instruments (a) YAR-2000 Microcomputer controlled electro-hydraulic servo pressure testing machine； (b) Scanning electron microscopy；(c) X-ray diffraction； (d) Mercury Intrusion Porosimetry\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/6aebef52f78a7fa7385a3312.png"},{"id":91421486,"identity":"a7ed8451-1039-45f8-bf27-d9e662bceb6e","added_by":"auto","created_at":"2025-09-16 10:18:49","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":33314,"visible":true,"origin":"","legend":"\u003cp\u003eMass loss map of cement-based material at 150d of sulfate attack\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/99dfec4cf83e83146f6d16c2.png"},{"id":91421488,"identity":"6313284e-cee0-4fc5-8f97-5c826d943cbb","added_by":"auto","created_at":"2025-09-16 10:18:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":36564,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in compressive strength of sulfate attack at 150d\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/3f57d8a6fc7145b92829118c.png"},{"id":91422779,"identity":"a5283824-001a-41e9-b660-52be59a5e526","added_by":"auto","created_at":"2025-09-16 10:34:50","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":138310,"visible":true,"origin":"","legend":"\u003cp\u003eXRD pattern after 0, 30, 60, 90, 120 and 150 days of sulfate attack\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/3d7511ea7804e62be0f8735b.png"},{"id":91422500,"identity":"76768014-217f-48d3-8d67-d5da89e840ff","added_by":"auto","created_at":"2025-09-16 10:26:50","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":557326,"visible":true,"origin":"","legend":"\u003cp\u003eSEM image of mortar with 150 sulfate attack (\u003cstrong\u003ea\u003c/strong\u003e)0d; (\u003cstrong\u003eb\u003c/strong\u003e)30d; (\u003cstrong\u003ec\u003c/strong\u003e)60d;(\u003cstrong\u003ed\u003c/strong\u003e)90d;(\u003cstrong\u003ee\u003c/strong\u003e)120d;(\u003cstrong\u003ef\u003c/strong\u003e)150d;\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/61b183a9a470d8eab9d845cf.png"},{"id":91421490,"identity":"99b54a72-12cc-4432-be43-6438c271a069","added_by":"auto","created_at":"2025-09-16 10:18:49","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":51368,"visible":true,"origin":"","legend":"\u003cp\u003eThe pore size distribution curves of the paste, mortar and concrete after 28 days of curing\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/9d7744910524dd0294b1453f.png"},{"id":91421492,"identity":"c0da7e69-7ac7-4af1-8f9f-a3268fccd2e8","added_by":"auto","created_at":"2025-09-16 10:18:50","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":108242,"visible":true,"origin":"","legend":"\u003cp\u003eThe stacking chart of pore changes of net paste, mortar and concrete after curing for 28 days\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/76e53bda183ba5a375ab2582.png"},{"id":91422777,"identity":"905a7bfe-b9c2-449f-a807-7ccd37f8d013","added_by":"auto","created_at":"2025-09-16 10:34:50","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":87602,"visible":true,"origin":"","legend":"\u003cp\u003ePore size distribution curve of 0d, 30d, 90d and 150d mortar subjected to sulfate attack\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/d0c8641c94e5738d347cd2eb.png"},{"id":91422781,"identity":"62e10f0e-d5a0-4e38-99f1-1f576990a5ef","added_by":"auto","created_at":"2025-09-16 10:34:50","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":104101,"visible":true,"origin":"","legend":"\u003cp\u003ePore change and accumulation map of 0d, 30d, 90d and 150d mortar subjected to sulfate attack\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/b94a56517e9a9706413f35a2.png"},{"id":91422504,"identity":"7cfbed3d-3918-43c6-9634-2bd872239df9","added_by":"auto","created_at":"2025-09-16 10:26:50","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":134459,"visible":true,"origin":"","legend":"\u003cp\u003eThe P, M and C magnetic resonance imaging analysis diagrams after 28 days of maintenance；(a)PMCT2 spectrum analysis curve(b) Pore distribution (c) pore change\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/b2845949f0d54c05199df0a1.png"},{"id":91422497,"identity":"4b1b9c82-a59c-429a-b562-75ca501dd6b9","added_by":"auto","created_at":"2025-09-16 10:26:50","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":141307,"visible":true,"origin":"","legend":"\u003cp\u003eNuclear magnetic resonance analysis diagram of mortar specimens after sulfate attack；(a)Analysis curves of the T2 spectra for different erosion ages of mortar(b) Pore distribution (c) pore change\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/6514473132ff575209f1ff1c.png"},{"id":97724582,"identity":"4a40dd50-95b4-4dbf-91da-7cc7bcf8f7cb","added_by":"auto","created_at":"2025-12-08 16:12:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3217474,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7526533/v1/a482b098-59ce-40db-ae40-fc64c1f2aa13.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Research on the Pore Distribution Characteristics and Strength Degradation of Cement-Based Materials under Sulfate Attack","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCement-based materials are the most extensively utilized construction materials globally, offering advantages such as ease of availability, cost-effectiveness, and excellent fire resistance. They find widespread application in residential buildings, bridges, roads, and various other structures [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Under standard conditions, cement-based materials exhibit commendable performance characteristics including compressive strength [\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], deformation capacity [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], and durability [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, due to their specific geographical locations or environmental conditions, structures situated in coastal regions [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and saline-alkali areas are subjected to prolonged exposure to factors such as saline-alkali solutions and steam. Among these influences, sulfate erosion is one of the more prevalent degradation mechanisms [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In such scenarios, sulfate erosion can compromise several mechanical properties of cement-based materials; consequently, for relevant construction projects and marine engineering applications affected by sulfate attack on cement-based materials, the overall structural durability may be diminished. This reduction poses significant risks to both life safety and property.\u003c/p\u003e\u003cp\u003eThe sulfate attack on cement-based materials can be primarily categorized into physical and chemical reactions [\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Physical reaction pertains to the crystallization of sulfates due to water evaporation and other factors during the sulfate erosion process [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Chemical reaction involves the interaction between sulfates and chemical constituents in cement-based materials, resulting in the formation of gypsum, ettringite, carburite, among others [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The degradation of concrete by sulfates is predominantly manifested through damage to hydrated calcium silicate gel, leading to a disruption of the original internal structural equilibrium of concrete [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Sulfate attacks typically present themselves in concrete as expansion and cracking phenomena [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. When cracks develop, the accompanying sulfate solution is more prone to infiltrating the internal pores of concrete [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], adversely affecting key properties such as strength and durability post-sulfate attack. Under these circumstances, sulfate exposure diminishes the strength of cement-based materials [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Consequently, for construction projects and marine engineering endeavors situated in saline environments, sulfate-induced erosion poses a significant threat to overall structural durability by compromising cement-based material integrity\u0026mdash;thereby endangering life safety and property.\u003c/p\u003e\u003cp\u003eCurrently, substantial advancements have been made regarding understanding how sulfates affect concrete erosion. Research conducted by Chindaprasirt et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] and Gao et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] examined damage characteristics under dry-wet cycling conditions\u0026mdash;including ion diffusion patterns, volumetric expansion behaviors, weight loss metrics, alterations in mechanical properties\u0026mdash;and confirmed that wet-dry cycling significantly influences concrete's damage progression compared with isolated sulfate environments. Meng et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] investigated high-performance synthetic fiber-reinforced concrete subjected to sulfate erosion; their findings indicated superior crack resistance and freeze-thaw resilience relative to conventional concrete types. Tan et al. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] analyzed load impacts on concrete columns through compression testing while discussing how sulfates influence these structures' performance attributes. Utilizing an extended numerical approach based on Ficks second law alongside second-order reaction dynamics principles,Wang et al.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] concentrated on developing numerical analytical simulations along with ion diffusion models under sulfuric action aimed at predicting erosive processes within sodium sulfate solutions impacting concretes.In addition,some scholars have explored corresponding studies concerning crack morphology within concretes exposed to sulphate attacks,and multi-faceted environmental changes induced by sulphate under complex conditions[\u003cspan additionalcitationids=\"CR30\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. However,much current analytical methodology examining dynamic effects exerted by sulphate upon concretes tends toward microscopic perspectives via SEM or XRD techniques[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]; systematic investigations focusing specifically upon clean pulp,mortar,and concretized responses remain relatively scarce.\u003c/p\u003e\u003cp\u003eThis paper aims at investigating pore modifications occurring within clean pulp,mortar,and concretized matrices subjected fully immersed into sulfonated mediums whilst quantitatively analyzing resultant pore transformations.By mitigating salt-induced deterioration across various forms comprising cements,this study seeks not only prolonging service lifespans but also minimizing disruptions arising from normal operational activities hindered due solely towards saliferous aggressions.Furthermore,it strives towards reducing waste generated through repetitive constructions necessitated owing damages inflicted onto existing infrastructures caused directly attributable back down salt-related erosions thereby contributing modestly towards sustainable development initiatives aimed ultimately lowering carbon dioxide emissions whilst promoting greener low-carbon methodologies throughout contemporary building practices.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1. Raw Materials\u003c/h2\u003e\n \u003cp\u003eThe cement utilized is P\u0026middot;O 42.5R grade from Xinjiang Tianshan Cement Co., Ltd. The chemical composition is detailed in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. The mixing water employed is tap water sourced from Kashgar; the superplasticizer used is a liquid polycarboxylic acid-based superplasticizer. The fine aggregate consists of river sand with a fineness modulus of 2.51, classified as medium sand, while the coarse aggregate comprises gravel with particle sizes ranging from 5 to 20 mm and an apparent density of 2650 kg/m\u0026sup3;.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eChemical composition of cement\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eIngredient\u003c/p\u003e\n \u003c/th\u003e\n \u003cth colspan=\"9\" align=\"left\"\u003e\n \u003cp\u003emass fraction/%\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCaO\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMgO\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLi\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e63.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2.Mix proportion\u003c/h2\u003e\n \u003cp\u003eIn this experiment, three types of cement-based materials\u0026mdash;namely clean pulp, mortar, and concrete\u0026mdash;were systematically designed. Maintaining a consistent water-cement ratio, a specific proportion of sand was incorporated into the clean pulp to produce mortar, followed by the addition of a certain amount of stone to the mortar to yield concrete. This approach aimed to investigate the variations in different properties of these three cement-based materials post-erosion. The mix design adhered to the guidelines outlined in \u0026apos;Masonry Mortar Mix Ratio Design Regulations\u0026apos; (JGJ/T 98-2011 of China) and \u0026apos;Ordinary Concrete Mix Ratio Design Regulations\u0026apos; (JGJ55-2011 of China). The slump for concrete was controlled within the range of 150\u0026ndash;180 mm. The mixing ratios for these cement-based materials are detailed in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCement-based material mix ratio\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eNumber\u003c/p\u003e\n \u003c/th\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eWater-binder ratio\u003c/p\u003e\n \u003c/th\u003e\n \u003cth colspan=\"5\" align=\"left\"\u003e\n \u003cp\u003eCement-based materials amount of each material/(kg\u0026middot;m\u003csup\u003e-3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWater\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStone\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003esuperplasticizer\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e508\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1451\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e219\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e627\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1254\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e448\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e896\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e896\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eNote: P, M and C are respectively clean pulp, mortar and concrete\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e2.3.Test method\u003c/h2\u003e\n \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.1 Sulfate Attack Regime\u003c/h2\u003e\n \u003cp\u003eIn this experiment, clean pulp, mortar, and concrete cube samples with dimensions of 100 mm \u0026times; 100 mm \u0026times; 100 mm were prepared. Following a standard curing period of 28 days, the samples were placed in an oven at 80\u0026deg;C for drying over a duration of 48 hours. Once cooled, the specimens were immersed in a saturated solution of 5% Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e for periods of 30 days, 60 days, 90 days, 120 days, and 150 days through complete submersion. After soaking, the specimens underwent another drying phase in an oven at 80\u0026deg;C for an additional period of 24 hours. The mass changes and compressive strengths of cement-based material specimens across each group at various ages were recorded; the average values from three test blocks per group were taken as final results.The press is shown in Fig.\u0026nbsp;1(a).\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.2 SEM Analysis\u003c/h2\u003e\n \u003cp\u003eScanning Electron Microscopy (SEM) analysis was performed using a Phenom PROX machine to examine eroded specimens at different ages,As shown in Fig.\u0026nbsp;1(b). Specimens that had been eroded were fractured into flat sheets with diameters less than 5 mm and thicknesses approximately between 2\u0026ndash;3 mm before being placed into a container filled with anhydrous ethanol to halt hydration processes; these sheets were subsequently baked in an oven set to maintain a temperature of 40\u0026deg;C for a duration of twenty-four hours. The dried sheets were then positioned on a loading platform and transferred to a vacuum gold sputtering apparatus for gold coating treatment prior to observation under electron microscopy equipment.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.3 X-ray Diffraction Analysis\u003c/h2\u003e\n \u003cp\u003eAn X-ray Diffraction (XRD) analysis was conducted utilizing instrumentation produced by Dandong Tongda Technology Co., Ltd., aimed at determining the phase composition within samples subjected to erosion over varying durations,as shown in Fig.\u0026nbsp;1(c). Eroded samples collected via core sampling techniques underwent immersion in anhydrous ethanol to cease hydration before being ground into powder form with particle sizes less than or equal to ten micrometers using mortar grinding methods; these powders were then analyzed using XRD equipment within scanning ranges from five degrees to ninety degrees employing continuous scanning protocols with step widths set at intervals of zero point zero two degrees.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.4 Mercury Injection Analysis\u003c/h2\u003e\n \u003cp\u003eMercury Intrusion Porosimetry (MIP) testing was executed utilizing the AutoPore IV9500 mercury intrusion porosimeter manufactured by McMurtry Equipment Co., Ltd.,as shown in Fig.\u0026nbsp;1(b). A sample measuring less than ten millimeters in diameter and approximately five millimeters thick was extracted from reserved specimens which had been soaked in anhydrous ethanol for forty-eight\u0026thinsp;\u0026plusmn;\u0026thinsp;0 .5 hours effectively terminating any ongoing hydration processes prior testing pore structure variations among specimens aged differently due to erosion effects; contact angle measurements registered at one hundred thirty degrees while aperture measurement ranged from zero point zero zero three micrometers up to three hundred sixty micrometers.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e\n \u003ch2\u003e2.3.5 Low-field Nuclear Magnetic Analysis\u003c/h2\u003e\n \u003cp\u003eNuclear Magnetic Resonance (NMR) Testing: The MesoMR12-060H-I high-precision magnetic resonance concrete microanalysis instrument produced by Suzhou NuoMai Analytical Instrument Co., Ltd. in China was used. Specimens measuring 40mm\u0026times;40mm\u0026times;4 mm were prepared, standard-cured for 90 days, and then placed in a vacuum water-retaining machine. After water retention was completed. The pore changes of specimens with different water-cement ratios were tested, with a pore size measurement range of 0.00002 to 200 \u0026micro;m.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"3. Results and analysis","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Mass change after sulfate attack\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e illustrates the changes in mass of cement-based materials subjected to sulfate attack over a period of 150 days. As depicted in the figure, the mass variations of clean pulp, mortar, and concrete specimens generally exhibit an initial increase followed by a subsequent decrease. At 60 days of exposure, both clean pulp and concrete reached their maximum mass change values, with increases of 1.22% and 0.73%, respectively. By day 150, the corresponding mass losses were recorded at 0.64% for clean pulp and 0.16% for concrete. The mortar specimen experienced its peak mass change at day 90 with an increase of 0.77%, while at day 150 it showed a further increase of only 0.274%. This phenomenon can be attributed to the reaction between sulfate ions and gelling materials that produces erosion products such as gypsum and ettringite, thereby enhancing the specimen\u0026apos;s mass initially; however, as erosion progresses over time, these products accumulate leading to expansion and cracking within the specimen which ultimately results in material loss.\u003c/p\u003e\n \u003cp\u003eFollowing sulfate-induced erosion, the trend observed in mortar is analogous to that seen in clean mortar samples. The incorporation of fine aggregates stabilizes pore distribution within the mortar matrix; consequently, this leads to a reduced relative change in quality post-erosion with more gradual fluctuations compared to other specimens. Initially increasing with prolonged exposure time due to erosion effects on structural integrity\u0026mdash;mortar begins experiencing reductions in quality thereafter as degradation sets in more prominently over time than previously noted trends suggest when coarse aggregates are included within concrete mixtures; thus resulting faster alterations during early stages owing primarily due interfacial transition zones formed from coarse aggregate addition\u0026mdash;these zones represent weak links susceptible towards sulfate attacks [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. Therefore relative changes regarding quality among concrete specimens are significantly influenced by these transitional interfaces where initial growth rates surpass those observed amongst mortars alongside earlier peaks occurring therein.\u0026quot;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 The change of compressive strength after sulfate attack\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates the variation in compressive strength over a period of 150 days under sulfate attack. As depicted in the figure, the compressive strength of the unaltered pulp specimen exhibited a general declining trend, with an initial value of 54.11 MPa prior to erosion and reaching a minimum of 23.34 MPa after 150 days of exposure. Conversely, both mortar and concrete specimens initially demonstrated a gradual increase in compressive strength followed by a decline. The maximum compressive strength for mortar was recorded at 55.67 MPa after 90 days of erosion, while it decreased to a minimum value of 47.71 MPa at the end of the 150-day period. For concrete specimens, peak compressive strength was observed at 59.15 MPa after being eroded for 60 days; however, this diminished to a minimum value of 45.20 MPa following complete erosion over the same duration.\u003c/p\u003e\n \u003cp\u003eThis phenomenon can be attributed to early-stage erosion where sulfate ions infiltrate cement-based materials and react with calcium hydroxide from cement hydration products to form gypsum; subsequently, gypsum interacts with aluminum-containing hydration products leading to ettringite formation. The resultant gypsum and ettringite progressively fill internal pores within cement-based material specimens, thereby contributing to an incremental rise in their overall strength [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. During this phase, enhancements in compressive strength are closely linked to alterations in porosity within these materials\u0026apos; structures. In contrast, during mid-to-late stages of erosion, expansive forces compromise pore integrity within cement-based materials resulting in reduced structural strength.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 XRD phase analysis\u003c/h2\u003e\n \u003cp\u003eTo understand the erosion products after sulfate attack, X-ray diffraction analysis was conducted on mortar specimens at 0 days, 30 days, 60 days, 90 days, 120 days, and 150 days of erosion. As shown in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, at 0 days, the main phases were silica, calcium oxide, calcium hydroxide, and calcium silicate, etc. After sulfate attack, the diffraction peak of calcium hydroxide remained, indicating that the hydration of cement had not stopped. At 30 days of erosion, ettringite was added as the main phase, suggesting that the sulfate attack was mainly due to the chemical reaction between sulfate ions and the hydration products of cement, resulting in the formation of ettringite and causing damage to the cement-based material [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e]. With the continuous increase of the erosion age, the types of products formed during the erosion process did not change.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 Microscopic morphology analysis by scanning electron microscopy\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e shows the SEM images of mortar specimens subjected to sulfate attack at 0d, 30d, 60d, 90d, 120d and 150d. It can be seen from the figure that the microstructure inside the specimens varies significantly at different attack ages. As shown in (a), the internal microstructure of the specimen at 0d of attack is relatively smooth, indicating good cement hydration. As shown in (b), at 30d of attack, the internal microstructure is different from the smooth surface of the unattacked specimen, with short columnar products generated inside and erosion products beginning to adhere to the surface. The pore diameter starts to decrease, indicating that the erosion products have been formed and are beginning to fill the pores inside the specimen. As shown in (c), at 60d of attack, there are a few pores and microcracks, indicating some damage. This is due to the increasing amount of erosion products, which causes microcracks in the specimen. As shown in (d), at 90d of attack, the internal pore surface has become uneven, with gypsum and ettringite covering the originally smooth surface and further filling the pores. At this point, the strength of the mortar reaches its peak. The filling effect of the internal products on the pores is greater than the effect of the decomposition of the cementitious materials on the strength, so the macroscopic manifestation is an increase in compressive strength and mass change. As shown in (e), at 120d of attack, a small amount of ettringite begins to form inside the specimen. As shown in (f), at 150d of attack, the internal morphology of the specimen is significantly different from the initial state. Due to the continuous accumulation of erosion products, a large number of needle-like ettringite products appear inside, causing the internal morphology to become honeycomb-like. The macroscopic manifestation is a decrease in compressive strength and mass change.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n \u003ch2\u003e3.5 Pore changes after sulfate attack based on mercury injection technique\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e illustrates the pore size distribution curve of clean slurry, mortar, and concrete after 28 days of curing. The figure indicates that, under a constant water-cement ratio, the cement clean slurry exhibits the largest pore distribution and porosity at 26.38%. Upon incorporating sand, there is a significant reduction in pores smaller than 100 nm and larger than 10,000 nm; consequently, the pore size distribution becomes more uniform and porosity decreases to 13.58%. With the addition of coarse aggregate, heterogeneity within the cement-based material increases, leading to an increase in harmful pores exceeding 10,000 nm compared to mortar; thus raising porosity to 20.06%.\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e presents a diagram depicting changes in pore structure and accumulation for clean pulp, mortar, and concrete over a curing period of 28 days. According to Academician Wu Zhongwei [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e], internal pore diameters in cement-based materials are classified into several categories: Level One: harmless pores (0 nm \u0026minus;\u0026thinsp;20 nm); Level Two: less damaging pores (20 nm \u0026minus;\u0026thinsp;50 nm); Level Three: harmful pores (50 nm -200 nm); Level Four: multiple holes (greater than 200nm). As illustrated in the figure, proportions of harmless holes, less harmful holes, harmful holes and multi-harmful holes in clean pulp are recorded as follows: zero percent for harmless holes; 6.06% for less harmful; 8.07% for harmful; and an overwhelming majority of 85.86% for multi-harmful holes\u0026mdash;indicating a predominance of detrimental structures due to fine cement particles being susceptible to environmental temperature fluctuations which lead them to shrink or expand.In contrast with mortar\u0026apos;s composition where proportions stand at: harmless holes (18.02%), less harmful (39.48%), harmful (15.66%) and multi-harmful (26.82%), it is evident that mixing sand significantly enhances both harmless hole ratios while reducing those categorized as multi-harmful due primarily to volume stability provided by fine aggregates which mitigate overall shrinkage within cement-based materials\u0026mdash;resulting in predominant volumes found within the diameter range of approximately ten-to-one hundred nanometers.For concrete samples analyzed post-coarse aggregate incorporation reveal proportions as follows: harmless holes at just above two percent (1.82%), slightly damaged at eight point five four percent (8 .54%), harmfully affected at seventeen point twenty-nine percent(17 .29%)and predominantly multiharmed structures comprising seventy-two point thirty-four percent(72 .34%). This shift reflects how stone filling complicates pore pathways while amplifying larger voids particularly around interface transition zones.\u0026quot;\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e shows the pore size distribution curves of mortar for sulfate attack at 0d, 30d, 90d, and 150d. From the figure, it can be seen that sulfate attack has a significant impact on the pore size range of 10 nm to 10,000 nm in the mortar. At 30d of sulfate attack, the mercury penetration in the 10 nm-100 nm range and the range greater than 10,000 nm is less than that of 0d, while the mercury penetration in the 100 nm-10,000 nm range is greater than that of 0d. The porosity rate decreases from 13.58% at 0d to 12.57% at 30d of sulfate attack. This is because in the early stage of sulfate attack, the sulfate will react with the hydraulic binder materials to generate expansive products to fill the pores, resulting in a decrease in porosity rate. At 90d of sulfate attack, the mercury penetration in the 0 nm-75 nm range and the range greater than 100,000 nm is less than that of 30d, while the mercury penetration in the 75 nm-100,000 nm range is greater than that of 30d. The porosity rate increases from 12.57% at 30d to 14.17% at 90d of sulfate attack. This is because in the middle and late stages of sulfate attack, as the reaction proceeds and the products accumulate, the generated expansive force increases, and when the expansive force exceeds the tensile strength of the pore limit, the internal structure of the specimen will be destroyed, causing the pores to enlarge. At 150d of sulfate attack, the mercury penetration in the range greater than 10,000 nm reaches the maximum, and the porosity rate increases to 18.27%. This is because in the late stage of sulfate attack, the sulfate products will continue to accumulate, and the expansive force will become\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e illustrates the changes in pore structure and accumulation patterns of mortar subjected to sulfate erosion over periods of 0, 30, 90, and 150 days. The diagram indicates that as the duration of erosion increases, the proportion of multi-damage pores initially decreases before subsequently rising. In uneroded mortar, the proportions of harmless pores, slightly damaged pores, harmful pores, and multiple damage pores were recorded at 18.02%, 39.48%, 15.66%, and 26.82%, respectively. After a period of 30 days under erosive conditions, these proportions shifted to 10.86% for harmless pores, 44.43% for slightly damaged ones, while harmful and multi-harmful pore percentages were noted at 15.07% and 29.62%. This change reflects a decrease in both harmless and harmful pore ratios alongside an increase in less harmful and multi-harmful categories due to expansion products generated by sulfate attack filling previously harmful voids\u0026mdash;effectively reducing their diameter into less damaging classifications. Following an additional erosion period leading up to day-90 results showed proportions at: harmless (16.49%), slightly damaged (29.72%), harmful (14.18%), with multiple damage increasing significantly to reach a total of (39.60%). Here again we observe a decline in both slight damage and harm categories while there is an uptick in both harmlessness as well as multiple damages observed post-erosion phase extending through day-150 where final measurements indicated: harmless holes at just (0 .59%), slightly harmed at (7 .41%), with significant rises seen within harmful holes reaching (19 .59%) along with more severely affected holes escalating dramatically to account for (72 .40%). Notably here too was evident reduction among benign or mildly impacted voids contrasted against notable increases within detrimental classifications; this phenomenon can be attributed primarily towards late-stage erosional processes wherein internal porosity becomes filled by resultant products yet continues generating further expansive forces which exacerbate crack propagation throughout mortar matrices thereby amplifying overall porosity levels [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003e3.6 Pore changes after sulfate attack based on low-field nuclear magnetic resonance technology\u003c/h2\u003e\n \u003cp\u003eThe transverse relaxation time T2 spectrum of nuclear magnetic resonance reflects the distribution of pore sizes in cement-based materials. The shorter the transverse relaxation time T2, the smaller the pore radius; the longer the transverse relaxation time T2, the larger the pore radius. The position of each peak in the T2 spectrum distribution curve is related to the pore size, and the size of the integral area of each peak reflects the change in the number of internal pores in cement-based materials [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eFigure 10 shows the nuclear magnetic resonance analysis diagrams of P, M, and C after 28 days of curing. From Figure (a), it can be seen that the nuclear magnetic resonance T2 spectra of P and M mainly present a \u0026quot;main peak\u0026quot; structure. The main peaks are all distributed at shorter transverse relaxation times, and the signal intensity shows P\u0026thinsp;\u0026gt;\u0026thinsp;M, indicating that the number of small pores inside P and M accounts for a larger proportion, with only a small part being large pores. The transverse relaxation time T2 of P is between 0.017 and 3217.642 ms, and that of M is between 0.022 and 4824.108 ms. The nuclear magnetic resonance T2 spectrum of C mainly presents a \u0026quot;main and secondary peak\u0026quot; structure. The main peaks are all distributed at shorter transverse relaxation times, and their signal intensity and the integral area under the distribution curve are significantly larger than those of the secondary peaks, indicating that the number of small pores inside the concrete accounts for a larger proportion, with only a small part being large pores. The transverse relaxation time T2 of C is between 0.02 and 2967.3 ms. It can be clearly seen from Figure (a) that the porosity of the paste specimens is relatively large, and with the addition of sand and gravel, the internal bonding force of the matrix is increased, and the fine and coarse aggregates are improved, thereby improving the pore structure, and the number of pores in the cement-based materials gradually decreases, and the porosity gradually decreases.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig.\u0026nbsp;10(b) and (c), the pore change accumulation diagrams of the paste, mortar, and concrete are presented. The proportion of various types of pores in P, M, and C is statistically described based on the nuclear magnetic resonance T2 spectrum distribution curve. It can be seen from the figure that the porosity of P is 24.93%, with the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores being 85.86%, 9.16%, 2.5%, and 2.46% respectively; the porosity of M is 8.88%, with the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores being 71.14%, 10%, 6.23%, and 12.62% respectively; the porosity of C is 11%, with the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores being 61.5%, 4.12%, 4.49%, and 29.87% respectively. For the paste, mortar, and concrete specimens, the porosity continuously decreases with the addition of sand, and increases with the addition of sand and gravel. The proportions of harmless pores, slightly harmful pores, and harmful pores decrease, while the proportion of highly harmful pores increases.\u003c/p\u003e\n \u003cp\u003eAnalysis of the reasons: The addition of sand and gravel improves the pore structure of the material to a certain extent. As aggregates, sand and gravel can fill some pores, reducing the formation of harmful and highly harmful pores, thereby increasing the density and overall performance of the material. However, after adding gravel to the mortar, although the internal bonding force of the matrix is further enhanced, more interface transition zones are introduced, which are often weak and prone to become concentrated areas of pores and micro-cracks, resulting in an increase in porosity, especially a significant increase in the proportion of highly harmful pores. In addition, the pore structure of the gravel itself may also affect the overall porosity.\u003c/p\u003e\n \u003cp\u003eFigure 10 The P, M and C magnetic resonance imaging analysis diagrams after 28 days of maintenance;(a)PMCT2 spectrum analysis curve(b) Pore distribution (c) pore change\u003c/p\u003e\n \u003cp\u003eFigure 11 shows the NMR analysis of M after 150 days of sulfate attack. As can be seen from Figure (a), the NMR T2 spectrum of M before erosion mainly presents a \u0026quot;main peak\u0026quot; structure. The main peaks are all distributed at the shorter transverse relaxation time, with T2 ranging from 0.022 to 4824.108 ms, indicating that the number of small pores inside M accounts for a large proportion, while only a small part are large pores. After erosion, the NMR T2 spectrum of M mainly presents a \u0026quot;main and secondary peak\u0026quot; structure. The main peaks are all distributed at the shorter transverse relaxation time, and the signal intensity and the area under the distribution curve of the main peaks are significantly greater than those of the secondary peaks, indicating that the pore structure inside the mortar has undergone significant changes after sulfate attack. The transverse relaxation time T2 of M after erosion ranges from 0.002 to 10000 ms.\u003c/p\u003e\n \u003cp\u003eAs shown in Figs. 11(b) and (c), they are the pore change accumulation diagrams of the mortar after sulfate attack. The proportion of pores in the mortar before and after erosion is statistically described in combination with the NMR T2 spectrum distribution curve. It can be seen from the figure that the porosity of M before erosion is 8.88%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 71.14%, 10%, 6.23%, and 12.62% respectively. After 30 days of erosion, the porosity is 7.60%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 77.93%, 3.91%, 4.13%, and 14% respectively. The proportions of harmless pores and highly harmful pores increase, while the proportions of slightly harmful pores and harmful pores decrease. After 90 days of erosion, the porosity is 6.91%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 83.35%, 2.85%, 2.85%, and 10.93% respectively. The proportion of harmless pores increases, while the proportions of slightly harmful pores, harmful pores, and highly harmful pores decrease. After 150 days of erosion, the porosity is 14.42%, and the proportions of harmless pores, slightly harmful pores, harmful pores, and highly harmful pores are 78.58%, 3.62%, 3.93%, and 13.86% respectively. The proportions of harmless pores and slightly harmful pores decrease, while the proportions of harmful pores and highly harmful pores increase. This is because, in the initial stage of erosion, sulfate will react chemically with the internal substances of the cement-based material to form gypsum and other substances, filling the internal pores of the specimen, reducing the porosity and the proportions of harmful pores and highly harmful pores. In the later stage of erosion, as the chemical reaction continues, the products increase. When the volume of the products reaches a certain amount, it will cause the specimen to crack, increasing the proportions of harmful pores and highly harmful pores.\u003c/p\u003e\n \u003cp\u003eThe pore changes of mortar specimens were analyzed by combining the pressure mercury method and nuclear magnetic resonance technology. It was found that there were certain differences in the porosity measured by the two methods, but the changing trends were consistent. This was mainly due to the different sample sizes tested by the two methods, which led to minor differences in the measurement results. The pressure mercury method is usually suitable for smaller volume samples and can more accurately reflect the local pore structure, while nuclear magnetic resonance technology is suitable for larger volume samples and can provide more comprehensive pore distribution information. Despite the differences, both methods indicated that with the increase of erosion age, the porosity of cement-based materials first decreased and then increased. By comprehensively analyzing the test results of the two methods, the influence mechanism of pore structure on the performance of cement-based materials can be better understood, providing important references for optimizing material ratios and improving material performance.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study focuses on cement-based materials, examining the impact of sulfate attack on the properties of clean pulp, mortar, and concrete. The following conclusions can be drawn:\u003c/p\u003e\u003cp\u003e(1) The quality variations in clean pulp, mortar, and concrete initially increase and subsequently decrease with prolonged sulfate exposure. Clean pulp and concrete reach their peak values at 60 days of exposure, increasing by 1.22% and 0.73%, respectively; whereas mortar attains its maximum value at 90 days of exposure with an increase of 0.77%.\u003c/p\u003e\u003cp\u003e(2) The compressive strength of clean slurry exhibits a decreasing trend as erosion age increases, reaching a minimum value of 23.34 MPa. In contrast, the compressive strengths of both mortar and concrete show an initial increase followed by a decline; after 150 days of erosion, the compressive strength for mortar decreases by 14.29%, while that for concrete declines by 19.34%.\u003c/p\u003e\u003cp\u003e(3) Among clean slurry, mortar, and concrete with identical water-cement ratios, the porosity is highest in clean slurry compared to both concrete and mortar. Following sulfate erosion treatment, the porosity in mortar first decreases before increasing again\u0026mdash;showing a reduction of 1.01% at day 30 but an increase of 5.7% at day 150.\u003c/p\u003e\u003cp\u003e(4) The pore changes of cement-based materials were analyzed by combining the pressure mercury method and nuclear magnetic resonance technology. It was found that there were certain differences in the porosity measured by the two methods, but the changing trends were consistent.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eYuhang Li:\u003c/strong\u003e Writing–review \u0026amp; editing, Conceptualization, Methodology, Supervision, Data curation, Project administration, Funding acquisition.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEnze Hao:\u003c/strong\u003e Writing–review \u0026amp; editing, Supervision, Conceptualization, Formal analysis, Validation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eXiumei Zheng:\u003c/strong\u003e Writing–review \u0026amp; editing, Conceptualization, Software, Formal analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDali Zhang:\u003c/strong\u003e Conceptualization, Methodology, Data curation, Software, Validation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWenbang Zhu:\u0026nbsp;\u003c/strong\u003eWriting–review \u0026amp; editing, Supervision, Project administration, Validation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRuiming Liu:\u003c/strong\u003e Resources, Validation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eXinjie Wang:\u003c/strong\u003e Validation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eYali Cao:\u003c/strong\u003e Resources, Validation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eChaochao Sun:\u003c/strong\u003e Resources.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDebo He:\u003c/strong\u003e Resources.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eChao Yang:\u003c/strong\u003e Resources.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGang Li:\u0026nbsp;\u003c/strong\u003eValidation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003cstrong\u003e：\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by the 2025 Xinjiang Uygur Autonomous Region Natural Science Foundation project (2025D01A05), Kashi University-level project (（2024）2930、（2024）2926),China National University Student Innovation \u0026amp; Entrepreneurship Development Program(202510763010,202510763149).Liaoning\u0026nbsp;Provincial\u0026nbsp;Institute\u0026nbsp;of\u0026nbsp;Construction\u0026nbsp;Science\u0026nbsp;Co.,\u0026nbsp;Ltd.2024\u0026nbsp;Key\u0026nbsp;Research\u0026nbsp;Project\u0026nbsp;of\u0026nbsp;Liaoning\u0026nbsp;Province\u0026nbsp;(2024JH2/102400016).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed Consent Statement:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed consent was obtained from all subjects involved in the study\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll data are available upon request from the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflict of interest\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eYao, A., Xu, J. \u0026amp; Xia, W. 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Research on the mechanism of pore structure on water transportation in cement-based materials[J]. \u003cem\u003ePLoS One\u003c/em\u003e. \u003cb\u003e20\u003c/b\u003e (7), e0327659 (2025).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Sulfate Corrosion, Cement-based Materials, Porosity, Quality change, Compressive strength","lastPublishedDoi":"10.21203/rs.3.rs-7526533/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7526533/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTo investigate the influence of sulfate erosion on the performance of cement-based materials, this study designed mortar, concrete, and mortar-aggregate specimens with a water-to-cement ratio of 0.35. The study examined the changes in performance over 30 days, 60 days, 90 days, 120 days, and 150 days of sulfate erosion, and the findings showed that: as the duration of sulfate erosion increased, the mass change and compressive strength of cement-based materials generally showed an increasing trend first and then decreasing trend. The mass change of mortar, concrete, and mortar-aggregate specimens was 0.64%, 0.274%, and 0.16%, respectively, after 150 days of sulfate erosion. The compressive strength of mortar, concrete, and mortar-aggregate specimens decreased by 56.86%, 14.29%, and 19.34%, respectively, after 150 days of sulfate erosion. The porosity of mortar, concrete, and mortar-aggregate specimens showed that the porosity of mortar was greater than that of concrete, which was greater than that of mortar-aggregate specimens. The porosity of mortar-aggregate specimens showed a trend of decreasing first and then increasing after sulfate erosion. The porosity of mortar-aggregate specimens reached 12.57% after 30 days of sulfate erosion and 18.27% after 150 days of sulfate erosion.\u003c/p\u003e","manuscriptTitle":"Research on the Pore Distribution Characteristics and Strength Degradation of Cement-Based Materials under Sulfate Attack","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-16 10:18:45","doi":"10.21203/rs.3.rs-7526533/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-23T13:03:20+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"67340676036397760822096260969198437454","date":"2025-09-21T06:22:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"216237084906945208923861890834069288321","date":"2025-09-20T00:39:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-19T18:51:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"27409034233569809018409266488897101464","date":"2025-09-18T13:41:46+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-17T20:37:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"326707572976477172593927759766185896878","date":"2025-09-16T14:55:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"225444295314380421493210082055597469716","date":"2025-09-14T08:57:00+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-14T07:33:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"129325666618785228417480191721121575006","date":"2025-09-09T11:16:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"24411409340850127137042724464599405328","date":"2025-09-09T05:50:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"13275570478447499807690271597011135817","date":"2025-09-09T05:46:21+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-09T05:44:13+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-09T05:31:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-07T16:13:28+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-05T01:54:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-09-03T11:24:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"312b7cb8-c7da-41f1-8024-e8ba03075662","owner":[],"postedDate":"September 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":54694545,"name":"Physical sciences/Engineering"},{"id":54694546,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2025-12-08T16:08:44+00:00","versionOfRecord":{"articleIdentity":"rs-7526533","link":"https://doi.org/10.1038/s41598-025-31233-5","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-12-07 15:57:43","publishedOnDateReadable":"December 7th, 2025"},"versionCreatedAt":"2025-09-16 10:18:45","video":"","vorDoi":"10.1038/s41598-025-31233-5","vorDoiUrl":"https://doi.org/10.1038/s41598-025-31233-5","workflowStages":[]},"version":"v1","identity":"rs-7526533","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7526533","identity":"rs-7526533","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}