Splitting Tensile Strength of Fly Ash-Modified Sand at Various Saturations and Curing Times

Currently, a soil stabilization approach using fly ash as an effective choice for increasing soil stiffness and strength has emerged. With the presence of water, the lime in the fly ash would be separated, generating cementitious materials binding the grains of sand. In the present study, the influence of curing time and saturation during specimen preparation on the behavior of fly ash-modified sand was observed by performing a series of splitting tensile strength tests. It was found that the splitting tensile strength increases with fly ash content and curing time and decreases with saturation. The splitting tensile strength produced at 30% saturation was approximately two-fold higher than 100%, particularly at one month of curing time. However, the splitting tensile strength at higher saturations approaches lower, especially at longer curing times. Porewater evaporation accelerates the self-hardening occurring over time during curing. By increasing the fly ash percentage from 5% to 20% in the mixture, the splitting tensile strength increased by up to twenty-fold in the present study. An equation has been proposed as a function of porosity/volumetric fly ash content, curing time, and saturation during the preparation of the specimen.

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