In this testing research, a series of High Performance Recycled Aggregate Concrete (HPRAC) with recycled aggregate were prepared and their mechanical behaviors were tested, especially uniaxial compressive stress-strain behavior. The influence of the recycled aggregate replacement on mechanical behaviors of HPRAC was studied by changing replacement ratio of recycled aggregate. Testing results show that the strength of HPRAC decrease a little with the increase of the content of recycled aggregate; the uniaxial compressive stress-strain curve of HPRAC is similar to that of ordinary concrete, and the ductibility of HPRAC improve with the increase of the content of recycled aggregate; the fitted regression curves (especially numerical model) approach to measured curves and can be used in constitutive relations analysis for concrete structure.

The activity index of steel slag-GGBS composite mineral admixture with different steel slag contents at the W/B of 0.3, 0.4, and 0.5 was investigated. The results show that the activity index of the composite mineral admixture with higher GGBS content is larger, and this phenomenon is more obvious at later ages. At lower W/B, the gap of activity index of different composite mineral admixtures is smaller. The activity index of each composite mineral admixture is higher at lower W/B and at later age. The steel slag-GGBS composite mineral admixture is more suitable to be used in high strength concrete than in low strength concrete. As far as the long-term properties of concrete are concerned, the activity index of the composite mineral admixture at the late age should be adopted.