长龄期中低热混凝土断裂性能试验研究

Fracture performance of long-aged moderate-heat and low-heat concrete

为了研究水泥种类对长龄期混凝土材料断裂参数的影响,采用楔入劈拉试验和强度试验的方法,再结合双K断裂理论,对比分析低热和中热硅酸盐水泥混凝土的断裂性能。试验结果表明:长龄期低热混凝土的抗压强度和劈裂抗拉强度与中热混凝土的比值分别为1.11、1.07倍;相同初始缝高比条件下,长龄期低热混凝土的起裂断裂韧度、失稳断裂韧度和断裂能明显高于中热混凝土;低热和中热混凝土的起裂断裂韧度都与初始缝高比无关,可视为材料的固有参数,失稳断裂韧度随初始缝高比的增加而减小;亚临界裂缝扩展量都随初始缝高比的增加而减小,随初始缝高比的增加,混凝土材料的韧性越差,裂缝扩展越不充分;相同初始缝高比条件下,中低热混凝土的亚临界裂缝扩展量相差不大。

To investigate the influence of cement type on the fracture parameters of long-aged concrete materials,it used the wedgesplitting test and strength test methods,combined with the double-K fracture theory,to compare and analyze the fracture performance of low-heat and moderate-heat Portland cement concrete.It was observed that the compressive strength and splitting tensile strength of long-aged low-heat cement concrete were 1.11 and 1.07 times than that of moderate-heat concrete,respectively.Under the same initial crack-depth ratio,the initial fracture toughness,unstable fracture toughness and fracture energy of long-aged low-heat concrete were significantly higher than that of moderate-heat concrete.The initial fracture toughness of low-heat and moderate-heat concrete was independent of the initial crack-depth ratio and can be regarded as the intrinsic parameters of the material,and the unstable fracture toughness decreased with the increase of the initial crack-depth ratio.Subcritical crack propagation length decreased with the increase of the initial crack-depth ratio,which indicated that the toughness of the concrete material was worse,and the crack propagation was less adequate.Under the same initial crack-height ratio,the subcritical crack propagation of moderate and low-heated concrete is not much different.