基于毛细孔张力理论的高强再生骨料混凝土收缩性能及预测方法研究

Performance and Prediction Methods Studies for High Strength Recycled Aggregate Concrete Base on the Capillary Tension Theory

基于毛细孔张力理论,对高强再生骨料混凝土的收缩性能及预测方法开展了研究工作。首先通过试验测试了不同母料强度、不同天然骨料取代率下的混凝土试件的力学性能、收缩以及孔隙特征。之后基于毛细孔张力理论,提出了高强再生骨料混凝土的收缩预测方法。结果表明:再生骨料混凝土的静力受压弹性模量、抗压强度低于同龄期的天然骨料混凝土;再生骨料混凝土的收缩将随着再生骨料母料强度下降、天然骨料取代率的增加而上升;受再生骨料母料弹性模量的影响,再生骨料混凝土的孔结构较天然混凝土更小;研究提出的基于毛细孔张力理论的预测方法,能够有效的预测高强再生骨料混凝土早龄期的收缩性能。研究成果对于解决高强再生骨料混凝土收缩开裂问题具有推动作用。

Based on capillary tension theory, the shrinkage performance and prediction methods of high strength recycled aggregate concrete were studied. First, the mechanical properties, shrinkage and pore characteristics of concrete specimens with different master batch strength and different natural aggregate replacement rates were tested. Then, a method for predicting shrinkage of recycled aggregate concrete was proposed based on capillary tension theory and microstructure pore of concrete. The test results show that the elastic modulus and compressive strength of recycled aggregate concrete are lower than that of natural aggregate concrete at the same age. The shrinkage of recycled aggregate concrete will increase with the decrease of the master batch strength and increase of the replacement rates. The recycled aggregate concrete is denser than the natural concrete due to the elastic modulus of the recycled aggregate. The proposed prediction method based on capillary tension theory can effectively predict the shrinkage of high strength recycled aggregate concrete at early age. The research results can help to solve the problem of cracking of high strength recycled aggregate concrete due to the shrinkage.