Abstract: In an attempt to study the correlation between water absorption rate and strength of recycled concrete, we conducted mechanical tests on designed recycled concrete and ordinary concrete as well for comparison. In the preparation of recycled concrete samples, we replaced natural coarse aggregate with recycled coarse aggregate (5-20 mm) in a ratio ranging from 10% to 100% with each ten percent as a test group (in a total of ten groups), and designed the water-binder ratio at three levels (0.3, 0.4, and 0.5). Furthermore we examined the impacts of curing age, coarse aggregate’s replacement ratio, and water-binder ratio on the relationship between water absorption rate and strength of recycled concrete. Results unveil that when replacement ratio stays within 0%-50%, the recycled coarse aggregate concrete features with high compressive strength and low water absorption rate; when replacement ratio is about 20%, the water absorption rate reduces to the minimum while the splitting tensile strength reaches the maximum. Moreover, water absorption rate of recycled concrete is in a logarithmic relationship with compressive strength, and a power function relationship with splitting tensile strength for both recycled and ordinary concretes. The conclusions offer new idea and approach for detecting the strength of concrete.

Key words: recycled concrete, coarse aggregate, water absorption rate, water-binder ratio, compressive strength, splitting tensile strength