Mechanical properties and improvement mechanism of microbial enhanced recycled permeable pavement concrete

HUANG Qingjian; QIN Xiao; XU Yiran; QUAN Haonan; ZHANG Linshen

Abstract：The enhancement effect on the performance of recycled pervious pavement concrete was studied through the repair of aggregates based on Microbial Induced Carbonate Precipitation(MICP)technology.The effects of recycled aggregate content and water-binder ratio on the compressive strength,splitting tensile strength and connected porosity of recycled pervious concrete were explored.Additionally,the improvement mechanism of recycled pervious pavement concrete performance through MICP technology was revealed by combining microscopic data such as nanoindentation hardness and elastic modulus of the recycled aggregate-cement paste interface region.Results indicate that the greater the recycled aggregate content,the stronger the enhancement effect of MICP.When the content of recycled aggregate is 20％and 50％,the splitting tensile strength of pervious concrete reached 1.96 MPa and 1.24 MPa,respectively,representing increases of 8.29％and 42.53％compared to pre-enhancement levels.Moreover,the mechanical properties of pervious concrete exhibit a trend of first decreasing and then increasing with an increase in the water-binder ratio.Once the water-to-binder ratio exceeds the flowability threshold,sedimentation and segregation of the paste were observed,negatively affecting the distribution of the connected porosity.Furthermore,MICP technology is found to effectively fill the original microcracks and pores of recycled aggregates,and enhance the microscopic mechanical properties of the recycled aggregate-cement paste interface area,which has a positive impact on the macroscopic performance of recycled pervious concrete.