Effects of stream curing on the pore structure of recycled aggregate concrete

Pore in steam-cured concrete affect its strength and durability, and the optimization of steaming system can improve the pore structure to some extent. However, the influence mechanism of evaporation on recycled aggregate concrete (RCA) remains unclear. In this paper, the effects of curing temperature (20°C, 40°C, 60°C and 80°C), steam curing time (6h, 9h and 12h) and pozzolans (slag powder and fly ash) on the compressive strength and pore structure of RAC were studied. The microstructure characteristics such as pore size and pore size distribution were analyzed by the mercury injection porosimetry. The results shown that steam curing can significantly improve the compressive strength and reduce the most probable aperture and average pore sizes of RAC. Moreover, the effect of slag powder on RAC pore structure is better than that of fly ash. And there is a linear correlation between the compressive strength and the average pore size of steam-cured RAC. This can be an important parameter for constructing future steam cured RAC strength prediction models.