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为考察等强度条件下粉煤灰掺量对混凝土抗裂性的影响,通过调整水胶比对15%、20%、25%三种粉煤灰掺量的混凝土进行了等强度设计,并在此基础上开展了胶凝材料水化热及混凝土极限拉伸值、干缩、自生体积变形等热学性能和变形性能测试。结果表明,通过调整水胶比得到的三种粉煤灰混凝土的抗压强度、轴向抗拉强度和抗拉弹性模量基本相当,实现了等强度设计;等强度条件下粉煤灰掺量提高,混凝土的极限拉伸值增加,干缩值降低,自生体积收缩变形减少,开裂敏感性降低;三种混凝土之间的绝热温升差异小于胶凝材料水化热的测试情况,说明孤立地由胶凝材料水化热来评价混凝土的抗温度应力开裂性能是不合适的。
In order to investigate the effect of fly ash content on the crack resistance of concrete under constant strength conditions, the strength design of concrete with 15%, 20%, 25% On this basis, the thermal properties of cementitious materials and concrete ultimate tensile values, shrinkage, self-deformation and other thermal properties and deformation properties of the test. The results show that the compressive strength, axial tensile strength and tensile elastic modulus of the three kinds of fly ash concrete obtained by adjusting the water-cement ratio are basically the same, so that the equal strength design is achieved. Under the condition of the same strength, the fly ash content Increase the ultimate tensile value of concrete, reduce the shrinkage value, reduce the shrinkage of self-generated volume and reduce the sensitivity of cracking. The difference of adiabatic temperature rise between the three concrete is less than that of hydration heat of cementitious material, It is inappropriate to evaluate the thermal stress cracking resistance of concrete by the hydration heat of the cementitious material.