Liquefaction resistance of polypropylene strips reinforced sand-fly ash blend under strain-controlled cyclic triaxial test

This paper embarks on the influence of fine grain (fly ash) addition and polypropylene reinforcement to attenuate the liquefaction potential of sand. Previous findings reported reviewing the liquefaction of sand under the influence of fines appear to be conflicting and contradicting. The present study strives to realize the impact of fly ash (non-plastic fines) on resisting the liquefaction susceptibility of sand by carrying out strain-controlled cyclic triaxial tests on (polypropylene fiber) reinforced and unreinforced samples. The fly ash was mixed in different proportions (up to 50%) of the dry weight of sand. Three independent sets of experiments were performed on sand-fly ash blends. In first set, sand-fly ash mixture without reinforcement; second by adding polypropylene fiber @ 0.5% of the weight of sand only; and third by mixing the fiber in the above percentage considering the total weight of sand-fly ash blend. The specimens were tested under axial strain of 0.5% (shear strain of 0.75%) and a frequency of 1 Hz. The results were summarized to understand the effect of different factors such as fly ash content, relative density, reinforcement on liquefaction. The results indicated an inconsistent correlation between the liquefaction resistance of sand and the percentage content of fly ash. The number of cycles to initiate liquefaction at first decreased and then increased and again reduced, on increasing the fly ash proportion. The shear modulus of the mixture also adhered to a similar trend. The addition of polypropylene fiber helped to delay the initiation of liquefaction and significantly postponed the deformation of the sand-fly ash matrix.