基于细微观结构的再生混凝土力学性能研究

Study on mechanical properties of recycled concrete based on micro-structure

选取5.0~10.0、10.0~16.0、5.0~16.0 mm这3种级配的再生粗骨料分别以60%、80%、100%取代率制备混凝土,结合抗压强度及扫描电镜试验,研究再生骨料级配及取代率对混凝土孔隙率、界面结构以及力学性能的影响。研究发现:不同级配条件下再生混凝土孔隙率随取代率的增加而增大,级配为5~16 mm再生混凝土孔隙率优于5~10、10~16 mm;各级配条件下再生混凝土抗压强度降低幅度随取代率的增加逐步提高,100%取代率时强度降低约23%左右;界面过渡区中最容易发生破坏的是骨料老界面和砂浆新界面,其次是骨料新界面。

60%,80% and 100% replacement rates were used to prepare concrete from three grades of recycled coarse aggregate(5.0~10.0 mm,10.0~16.0 mm and 5.0~16.0 mm).Combined with compressive strength and scanning electron microscope test,the effects of recycled coarse aggregate gradation and replacement rate on the porosity,interface structure and mechanical properties of concrete were studied.The results show that the porosity of recycled concrete increases with the increase of the replacement rate under different grade conditions.The porosity of recycled concrete with gradation of 5~16 mm is better than that of 5~10 mm and 10~16 mm.The reduction range of compressive strength of recycled concrete at all levels increases with the increase of replacement rate,and the strength decreases by about 22% when the replacement rate is 100%.In the interfacial transition zone,the most prone to damage are the old interface of aggregate and the new interface of mortar,followed by the new interface of aggregate.