初始缝高比、骨料粒径对混凝土断裂性能的影响

Effect of different initial crack-depth ratios and aggregate size on fracture properties of low-heated concrete

为了研究初始缝高比和最大骨料粒径对低热混凝土断裂参数的影响,设计了试件有效尺寸为300 mm×300 mm×120 mm,初始缝高比分别为0.2、0.4、0.6、0.7,最大骨料粒径分别为10、20 mm的低热混凝土楔入劈拉试验,基于双K理论模型分析初始缝高比及最大骨料粒径对低热混凝土断裂参数的影响。结果表明:粗骨料对裂缝的扩展有阻碍作用,骨料粒径越大,混凝土的双K断裂参数和断裂能越大;相同试件尺寸条件下,起裂断裂韧度与初始缝高比无关,可认为是混凝土材料的固有参数;失稳断裂韧度、断裂能随初始缝高比的增大而减小。

In order to research the influence of the initial crack-depth ratio and maximum aggregate size on fracture properties of low-heated concrete,wedge-splitting specimens with the effective size was 300 mm×300 mm×120 mm,initial crack-height ratio were0.2,0.4,0.6,0.7,the maximum aggregate size were 10,20 mm respectively are designed and fracture tests were carried out.The influence of initial crack-height ratio and maximum aggregate size on the fracture properties of low-heated concrete based on the double-K fracture model.The results show that coarse aggregate can impede the crack propagation.The larger the aggregate size,the larger the double-K fracture parameters and the fracture energy of the concrete.Under the same size,the initial fracture toughness is independent of the initial crack-height ratio and can be considered as intrinsic parameters of the concrete.Unstable fracture toughness and frature energy decrease with increase of the initial crack-height ratios.