Small Strain Stiffness Properties of Cement-Stabilized Sand Reinforced with Polypropylene Fibre

Mechanical and chemical stabilization, as well as the soil reinforcement methods, are common soil improvement techniques; selecting each depends primarily on the type of project and stabilization purpose. Considering the positive effects of adding cement to sandy soils for stabilization and also reinforcing them by polypropylene fibres, evaluating the dynamic properties of such mixtures, especially their small strain shear modulus, seems indispensable for design purpose. In this study, 12 mixtures with different cement contents (3%, 5%, and 7% of dry sand weight) and various polypropylene fibre percentage (0%, 0.2%, 0.4%, and 0.8% of dry sand weight) were constructed, cured for 7, 28, and 56 days, and tested using a pair of bender elements for the estimation of shear wave velocity and maximum shear stiffness. Due to the obtained results, it was observed that the specimen stabilized with 7% cement content and reinforced by 0.4% polypropylene fibre inclusion was the most suitable composition to provide the most possible shear wave velocity and shear stiffness. Indeed, on the one hand, the increases in the amount of cement and curing time significantly enhance the stiffness of resultant mixtures. On the other hand, 0.4% of polypropylene fibre was found to be the optimum content in the composition so as to render the maximum small strain shear modulus.