Effect of Hybrid Fiber Reinforcements on the Mechanical and Ductility Performance of HPC Incorporating Micro Silica and Alccofine-1203 Prabath, N V N a , and Ramadoss, P b

This study investigates the effect of fiber volume fractions of single and hybrid fibers on the mechanical and ductility performance of high-performance concrete (HPC) with w/b ratios of 0.38 and 0.28, and 20% silica fume replacement. Macro steel fiber volume fractions (Vf = 0.5, 1 & 1.5%) and micro polypropylene fiber volume fractions (Vf = 0.25, 0.5 & 1%) and alccofine-1203 as an additive were used in this study. For high performance fiber reinforced concrete (HPFRC) and high performance hybrid fiber reinforced concrete (HP-HyFRC) mixes, compressive strength, modulus of rupture (MOR) and elastic modulus were evaluated. Test results of HPSFRC show improvement in 28-day compressive strength by 15.4% and in MOR by 44.66% at steel fiber volume fraction, for HPPFRC, improvement in compressive strength and in MOR the improvement is moderate at polypropylene fiber volume fraction, Vf = 1%. Stress-strain behavior of HPFRC and HP-HyFRC was studied and modulus of elasticity was obtained in the range of 33.72-44.26 GPa and 33.72-45.21 GPa, respectively. Engineering properties were improved as a result of synergetic effect between steel and polypropylene fibers. Effect of addition of alccofine-1203 on the mechanical performance of HPC was examined, and the optimum dosage as 8% was observed. HPSFRC improved the compressive toughness and ductility considerably, which is evidenced from stress-stain behavior, and in HP-HyFRC, this improvement is high due to the synergetic effect between both the fibers. Statistical models for the estimation of compressive strength ratios/ flexural strength ratios of HPSFRC/ HPPFRC were developed. The predicted values are in good agreement with the experimental values of earlier researchers. Relationship between 28-day flexural and compressive strengths of HPSFRC/ HPPFRC was developed with AAE= 4.32%. Multiple linear regression model with R= 0.98 was developed by Response surface method for the prediction of compressive strength of HP-HyFRC mixes and validated.