Small-strain dynamic properties of silty clay stabilized by cement and fly ash

This study examines the small-strain dynamic properties of cement-stabilized silty clay (CSC) and cement-fly ash-stabilized silty clay (CFSC). A series of resonant column tests were performed to investigate the effect of confining pressure, binder content and curing age on the small-strain dynamic shear modulus (G) and damping ratio (D) of CSC and CFSC. Furthermore, the maximum dynamic shear modulus (Gmax) and maximum damping ratio (Dmax) of CSC and CFSC were also evaluated. The results showed that the G of CSC and CFSC increased with the increase of confining pressure, binder content and curing age. The G decreased slowly and then rapidly with shearing strain (γ), and the γ of 10−4 was the turning point of evaluating the small-strain dynamic behavior of CSC and CFSC. Using 5% cement together with 30% fly ash as stabilizer has advantageous over using 15% cement alone in improving the stiffness properties of silty clay. The D of CSC and CFSC decreased with the increase of confining pressure and curing age, but increased with an increase in cement and fly ash content. This was attributed to the weakly cemented and rough of soil particles led to more energy dissipation of vibration wave propagating through the sample. The microstructural analysis revealed that the micro-aggregate effect and hollow structure of fly ash particles not only contributed to the improvement in G, but also effectively improve the energy dissipation performance of CFSC.