Properties of recycled aggregate concrete prepared with scattering-filling coarse aggregate process

Abstract

RAC produced with crushed recycled aggregate (RA) is regarded as an environmental friendly material, while its high water demand, high mortar content and low modulus have restricted its application. Scattering-filling coarse aggregate (SFCA) process was applied to prepare the recycled aggregate concrete with promoted performance. With the reference of conventional concrete and the scattering-filling natural aggregate (SFNA) concrete, the influences of ratio, type, size and moisture state of RA on mechanical and durable properties of scattering-filling recycled aggregate (SFRA) concrete were investigated. The results indicate that SFCA process could improve the compressive strength, elastic modulus, and reduce the drying shrinkage and chloride penetration. The frost resistance of SFRA is comparable with the conventional concrete. With 10–20 mm scattering-filling aggregate of RA, SFCA concretes get more significant improvement on elastic modulus and anti-permeability; Higher water content of RA worsen the performance of recycled aggregate concrete (RAC) for water in the RA weakening ITZ; Furthermore, image processing analysis and microhardness indicated that SFCA process improve the properties by increasing the homogeneity of aggregate distribution and improving ITZ between the aggregate and cement paste in RAC. SFCA process provides an economic method to produce high-quality recycled aggregate concrete and an efficiently approach to the utilization of recycled concrete aggregate from Construction and Demolition waste.