Dynamic Mechanical Properties of Nano-Silica Modified Recycled Aggregate Concrete under Uniaxial Compression

Abstract:

A novel method to modify recycled aggregate concrete （RAC） by nano-silica， two steps modification of nano-silica， and cement slury， was proposed in this paper. The stress-strain curves of RACs under uniaxial compression which were modified by three different methods at different strain rates （10^-5s^-1， 10^-3s^-1， and 10^-1s^-1） were obtained by conducting dynamic uniaxial compression test to explore the distinction between the curves before and after modification （two steps modification by nano-silica and cement slury， combined modification by nano-silica and fly ash， pre-soaking modification by nano-silica）. The results show that the novel modification method proposed could effectively promote the mechanical properties of RAC. Under the quasi-static condition， the peak stress and elastic modulus were increased by 25.1% and 85.8%， respectively. The dynamic increase factors（DIF） of the peak stress and elastic modulus of the modified RAC was decreased while the DIF of peak strain was increased. Finally， the dynamic stress-strain model of modified RAC was proposed， and the comparison results indicate that the predicted curves were in good agreement with the experimental curves， which can provide references for the engineering design and applications.