Study on the strength mechanism of red clay improved by waste tire rubber powder

The objective of this research is to improve the strength characteristics of red clay as a subgrade filler and increase the stability of subgrade engineering. During the laboratory tests, different amounts of waste tire rubber powder were added to the red clay. This study aims to identify the optimal amount of rubber powder required to improve the strength characteristics of red clay using a triaxial test and Duncan–Chang model. Using the depth of a field microscope, the apparent morphology of red clay and modified red clay was analyzed, and the pore variation of plain red clay and rubber powder modified red clay was described using a mercury intrusion test(MIP). The experimental results indicate that the asymptotic value of the main stress difference is significantly higher than the other four admixtures at 3%. The 3D surface comparison chart indicates that the addition of rubber powder significantly increases the relatively flat area range while reducing the overall area range. According to the comparison of porosity and contact area ratio, RPA1 is larger than RPA2, and RCA1 is smaller than RCA2. According to the characteristics of BJH pore size distribution, modified red clay has a higher pore fractal dimension than pure red clay.