基于细观尺度的再生混凝土多相导热系数理论模型

Theoretical Model of Multiphase Thermal Conductivity of Recycled Concrete Based on Mesoscale

为分析再生混凝土导热系数变化机理,进行了再生混凝土导热系数理论模型研究。在细观尺度上,将再生混凝土看作由新硬化砂浆、天然骨料、界面过渡区、孔隙相组成的四相复合材料。采用等效化方法,建立了界面过渡区导热系数模型并进行了验证,同时定义了等效界面过渡区(NITZ)影响系数η,η与再生混凝土导热系数有显著的线性关系。基于复合材料导热系数计算模型,利用η建立再生混凝土导热系数理论模型,计算结果与测试结果吻合较好,误差小于6%。在此基础上,根据该模型分析了各相组分导热系数、水灰比、骨料取代率、孔隙饱和度等因素对再生混凝土导热系数的影响,揭示了再生混凝土与普通混凝土传热差异,为再生混凝土传热机理的进一步研究提供了理论基础。

In order to analyze the mechanism of the change of thermal conductivity for recycled concrete,a theoretical model of the thermal conductivity of recycled concrete was investigated.On the mesoscale,the recycled concrete is regarded as a four-phase composite material composed of new hardened mortar,natural aggregate,interface transition zone and pore phase.Using the equivalent method,the thermal conductivity model of interface transition zone was established and verified,and the NITZ impact factorηwas defined,which has a significant linear relationship with the thermal conductivity of recycled concrete.Based on the thermal conductivity model of composite materials,a theoretical model of the thermal conductivity of recycled concrete was proposed by usingη.The calculated results of the model agree basically with experimental results,and the error is less than 6%.On this basis,the influence of factors such as thermal conductivity of each phase component,water-cement ratio,aggre-gate replacement and pore saturation level on the thermal conductivity of recycled concrete was analyzed by the model,revealing the difference in heat transfer between recycled concrete and normal concrete,and laying a theoretical foundation for further research on the heat transfer mecha-nism of recycled concrete.