粗骨料随机分布对混凝土导热性能的影响

Effects of Randomly Distributed Aggregates on Thermal Properties of Concrete

采用COMSOL与MATLAB联合仿真的方法,基于混凝土二维细观几何模型,实现了混凝土稳态热传导的数值模拟.在利用试验结果验证数值模拟有效性的基础上,分析了骨料随机分布对混凝土导热性能的影响,并讨论了粗骨料粒径、形状及其体积分数,以及分散相导热系数对混凝土导热性能的影响规律.结果表明:粗骨料随机分布是造成混凝土导热性能产生随机性的重要因素;混凝土导热系数相对平均值随着粗骨料体积分数、分散相导热系数的增加而增大,但受粗骨料粒径和形状的影响不大;粗骨料体积分数越高,分散相与水泥砂浆导热系数相差越大,粗骨料粒径越大,轴长比越大,混凝土导热系数的变异性越显著,但当粗骨料体积分数超过35%后混凝土导热系数的变异性基本保持不变.

Based on the meso-scale model of concrete, a simulation method combining COMSOL with MATLAB was used to inverse heat conduction problems of concrete in steady state. With the verified sim- ulation method, effects of randomly distributed aggregates on thermal conductivity of concrete were ana- lyzed, and influence of aggregate content, aggregate gradation, aggregate shape and thermal conductivity of the dispersed phase were also discussed. It has been shown that coarse aggregate distribution is an im- portant factor causing randomness of thermal conductivity of concrete. The average thermal conductivity of concrete increases with the increased volume content and thermal conductivity of aggregate, while aggre- gate size and particle-shape have little impact on the average thermal conductivity of concrete. Thermal conductivity increases with the increasing aggregate volume content, but remains unchanged if aggregate volume content exceeds 35%. It is also found that the thermal conductivity of concrete changes more sig- nificantly with the increase of proportion of large particle aggregates, the axial length of aggregates and the difference of thermal conductivity between dispersed phase and cement mortar.