Improvement of Liquefaction Resistance and Stiffness of Sandy Soils Using Fiber and Cement

Abstract Seismically induced liquefaction concerns natural deposits of both loose sands (Dr <50%) and fine silty sands, which can be present both in the subsoil and in the slopes at medium-low depths. This research shows the effect of random polypropylene fibers and cement in improving the resistance to liquefaction and shear modulus of loose sand deposits. A Series of laboratory undrained cyclic strain-controlled triaxial tests and cyclic stresscontrolled triaxial tests has been conducted as per ASTM D3999 and ASTM D5311. Cemented specimens were prepared with different cement contents up to 5% by mass of dry sand, then cured for different periods of time. The fibers were added to dry sand–cement mixtures with contents of 0%, 0.5%, and 1.0% by weight. It was found that the shear modulus and liquefaction resistance of specimens increased as the fiber content, fiber length and cement content increased. The addition of 1% polypropylene fiber(PF) to 5% cement (C)increased the shear modulus by 955.20%. The percentage of increase of shear modulus of specimens increases as the cell pressure increases. The duration of the curing period has a significant effect on the shear modulus of reinforced sand specimens. The relative density has a great effect on decreasing the generation of the excess pore water pressure.