为确定混凝土的弹性模量,基于细观层次假定混凝土是由骨料、砂浆和两者之间的粘结界面组成的三相复合材料,借助蒙特卡罗方法和瓦拉文公式,在二维平面上建立了随机骨料模型。通过有限元法预测混凝土的弹性模量,并将数值计算结果与试验结果进行比较,验证了该细观有限元模型的有效性。在此基础上研究了混凝土各细观组成成分的弹性模量、骨料体积率、骨料最大粒径、骨料级配、界面厚度以及孔隙等因素对混凝土弹性模量的影响规律。结果表明:在混凝土的各细观组成成分中,砂浆弹性模量对混凝土弹性模量的影响最大;连续级配的混凝土弹性模量在相同条件下大于间断级配的混凝土;孔隙的存在以及界面层厚度的增大均会使混凝土的弹性模量减小。研究结果为混凝土配合比的设计及力学性能的优化提供参考。
Abstract
In the assumption at mesoscopic level, concrete materials are assumed as three-phase composites consisting of aggregate, mortar and the bonding interface between mortar and aggregate. In order to determine elastic modulus of concrete (EMC), on the basis of the assumption, we establish a random aggregate model in the two-dimensional plane with Monte Carlo method and Walraven formula. Meanwhile, we predict EMC by using finite element method and compare the numerical calculated results with test results to verify the effectiveness of this mesoscopic finite element model. Furthermore, we discussthe impacts of several parameters (elastic modulus, aggregate’s volume content , aggregate’s maximum size, aggregate’s gradation , interface thickness and pores) of mesoscopic component on EMC. Test results show that 1) as for mesoscopic components of concrete, impact of elastic modulus of mortar on EMC is the biggest; 2) under given conditions, EMC with continuous gradation is bigger than that with uncontinuous gradation; 3) EMC decreases with the increasing of interface thickness and the existence of pores. The research results offer reference for the design of concrete’s mix proportion and optimization of its mechanical properties.
关键词
混凝土 /
复合材料 /
随机骨料模型 /
弹性模量 /
预测
Key words
concrete /
composite material /
random aggregate model /
elastic modulus /
prediction
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参考文献
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基金
国家自然科学基金面上项目(51379178);中央高校基本科研业务费专项资助项目(ZD2012015)
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