基于骨料断裂率的混凝土断裂力学性能研究

Study on concrete fracture performance based on fracture rate of aggregates

为了从细观层次上研究混凝土的断裂力学性能,采用图像分析法计算了三点弯曲试验中试件断裂面上的骨料面积,得到骨料断裂率AF/A,定性分析了混凝土抗拉强度、抗压强度与骨料断裂率的关系。分析结果表明:骨料断裂率随混凝土强度提高而增大且逐渐趋近于50%。对比各断裂参数随混凝土骨料断裂率的变化规律发现,CMODc、CTODc和wc随骨料断裂率的变化较小,断裂能随骨料断裂率的提高先增大后减小,在AF/A为42.9%处取得最大值。

In order to study the fracture performance of concrete in meso-level,an image analysis method was used to calculate the aggregate area on fracture surfaces of the specimens subjected to three point bending. The fracture rate of aggregate（AF/A） was determined; furthermore,the relationships between the AF/A and the tensile strength and compressive strength of concrete were analyzed qualitatively. The analysis results show that the AF/A increases with the increase of strengths of concrete and gradually tends to 50%. By comparing the change of fracture parameters with the AF/A,it can be found that the CMODc,CTODcand wc change little with the AF/A while the fracture energy increases firstly and then decreases with the increase of the AF/A. When the AF/A is about 42. 9%,the fracture energy reaches the maximum.