再生混凝土吸水率与强度的相关性研究

为研究再生混凝土吸水率与强度的相关性,选用5~20 mm的再生粗骨料取代天然粗骨料,以再生粗骨料取代率为10%～100%(每10%为一组,共取10组)、3种不同水胶比(0.3,0.4,0.5)的再生混凝土设计试验方案,并选用普通混凝土(取代率0%)作为对照组。在试验组和对照组共同试验的情况下,探讨养护龄期、取代率、水胶比对再生混凝土吸水率与强度的影响规律。结果表明:当取代率保持在≤50%范围内,用再生粗骨料制作的混凝土抗压强度高并且吸水率较低;再生粗骨料取代率在20%附近时,再生混凝土吸水率最低,劈拉强度最高;再生混凝土吸水率和抗压强度这2个检测指标间存在对数关系;再生混凝土和普通混凝土的劈拉强度与吸水率之间也呈幂函数关系。以上结论为检测混凝土强度提供了新的思路和方法,在实际工程中具有重要的指导意义。

Correlation Between Water Absorption Rate and Strength of Recycled Concrete

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.