Mechanical properties, pore structure and freeze-thaw resistance of recycled aggregate concrete based on ash of mushroom and corn straw

Abstract

Solid wastes, including granulated blast furnace slag (GBFS) and low-carbon mushroom-corn straw mixed biomass ash (MCA), are utilized to create supplementary cementitious materials (MCG) on a 1:1 basis in place of cement in response to the Global Carbon Reduction Initiative (GCRI). This study examines the regular relationships of seven types of recycled aggregate concrete (RAC) with varying MCG substitution rates (0 %, 7 %, 14 %, 21 %, 28 %, 35 %, and 42 %). These multiscale properties include slump, strength at various ages, freeze-thaw resistance, hydration characteristics, and pore structure characteristics based on NMR. With a 28-day compressive strength of 45.6 MPa, the highest percentage of transition and capillary holes at 79.13 %, and the lowest rate of mass and strength loss at 36 freezes and thaws at 0.35 % and 17.65 %, respectively, the results indicate that MCGRC has the best overall performance at a 21 % MCG substitution rate. Furthermore, there are notable quadratic and linear correlations between the MCGRC compressive strength and the alkalinity of the pore solution and chemically binding water, respectively.