再生混凝土导热性能影响因素及研究进展

Review on Thermal Conductivity of Recycled Concrete

再生混凝土因掺入再生骨料使其内部微观结构、力学与热力学性能均与普通混凝土有所区别。目前,对再生混凝土力学性能已有较多研究,但对其热力学性能的关注则相对较少。针对影响再生混凝土导热性能的主要因素,如再生骨料性质与取代率、再生微粉、环境温度等,分析再生混凝土导热系数的变化规律。通过归纳分析现有试验数据,提出了再生混凝土导热系数经验预测公式。此外,现有研究表明,再生骨料孔隙率直接影响再生混凝土导热系数,掺入再生骨料和再生微粉后,混凝土的导热系数明显下降,细骨料全取代时下降幅度可达48%;随环境温度升高,混凝土导热系数明显降低。

Recycled aggregate concrete(RAC)is different from ordinary concrete in its internal microstructure,mechanical and thermodynamic properties due to the addition of recycled concrete aggregates(RCA).At present,there have been many studies on the mechanical properties of RAC,but less attention has been paid to its thermodynamic properties.In this paper,effects of several important factors such as physical properties and replacement level of RCA,recycled concrete powders,and service temperature on the thermal conductivity of RAC are reviewed.Based on the experimental data in literature,an empirical equation for predicting the thermal conductivity of RAC is proposed.Existing studies show that the porosity of RCA affects the thermal conductivity of RAC.The incorporation of RCA and recycled concrete powder as well as the increase of ambient temperature can lead to a significant decrease in the thermal conductivity of concrete and with 100%recycled fine aggregate,the reduction of thermal conductivity can reach 48%.Functionalized RAC together with an enhanced mechanical performance would promote a wider industrial application and lead to less CO2 emission of the construction industry.