Previous researches have pointed out that recycled aggregate concrete (RAC) has inferior properties because of the old mortar attached to the recycled aggregate (RA).In order to promote the structural application of RA,the RAs modifications have been investigated,including physical methods,chemical methods and microbial methods.In this paper,two novel modification methods with nano-material and microbial precipitation proposed by authors,to enhance the properties of RA,are introduced.The great improvements in micro and macro properties of RAC were found after the surface treatment with nano-material.Meanwhile the properties enhancements of RA were also revealed with an optimum microbial precipitation modification.Moreover together with natural aggregate concrete,non-modified and nano-material slurry modified RAC were applied in three beams in a real project.In situ strain monitoring in the target beams showed the improved resistance to cracking of RAC after modification.This paper aims to make a contribution to making RAC suitable for structural concrete by modifying RAs.