Abstract: The aim of this study is to investigate the influence of recycled aggregate with surface-coating cement slurry on the early plastic cracking performance of self-compacting recycled concrete. On the basis of optimal mix proportions obtained from orthogonal test, we conducted early plastic cracking test via slab test with the strength level of surface-coating cement as single variable and other factors remaining unchanged. Test results demonstrate that after the surface-coating of recycled coarse aggregate, the compressive strength and flexural strength of concrete both improved, and the crack area also declined to different degrees. The total crack area of recycled concrete per unit area is about 1.5 times of that of ordinary concrete; and the crack area of concrete with 32.5R, 42.5R and 52.5R cement coating reduced by 11.1%, 25.1% and 13.1% compared with that of ordinary concrete, respectively, of which 42.5R cement boasts the best surface-coating effect. SEM test also shows that the surface-coating slurry of aggregate strengthens the interface transition zone of concrete and enhances its cracking resistance.

Key words: recycled coarse aggregate, surface-coating slurry of aggregate, early plastic cracking, cracking area, microstructure