配制方法对再生混凝土基本力学性能的影响

Influence of mixing methods on mechanical behaviors of recycled aggregate concrete

实验室配制再生混凝土时,一般采用再生骨料饱和面干法(PMA),此外,也有两阶段拌合法(TSMA)、等量砂浆含量法(EMV)与直接加水法(MWC)等其他配制方法以提高再生混凝土基本力学性能或简化其配制过程。为了便于实现再生混凝土在结构工程领域的商品化,通过试验研究,对比了这4种配制方法对再生混凝土抗压强度、弹性模量和收缩性能的影响。试验结果表明:采用两阶段拌合法(TSMA)配制的再生混凝土与饱和面干法(PMA)配制的相比,其抗压强度、弹性模量与收缩性能最大仅降低4.7%。在不显著影响再生混凝土基本力学性能的前提下,TSMA法省略了再生骨料的饱和面干处理过程,便于工程应用。在此基础上,将现有再生混凝土弹性模量和收缩模型与两阶段拌合法(TSMA)配制的再生混凝土试验数据进行对比,验证了模型的可行性。

Pre-saturation mixing approach (PMA) is generally recommended for recycled aggregate concrete (RAC) to achieve a sufficient workability and better mechanical behaviors. Other mixing methods, including two-stage mixing approach (TSMA), equivalent mortar volume (EMV) method and mixing water compensation (MWC) approach are proposed to improve the RAC mechanical properties or to simplify the mixing procedures. In order to promote the commercial applications of RAC in structures, this study presents an experimental investigation, aiming at the evaluation of the influence of typical mixing methods on the mechanical behaviors of concrete made of recycled coarse aggregates (RCA), i.e. compressive strength, elastic modulus and shrinkage deformation. Experimental results show that the mechanical property (i.e. compressive strength, elastic modulus and shrinkage deformation) of RAC made with TSMA presents a maximum decrease of 4.7% when compared to that of PMA. The pre-saturation procedure of RCA could be removed when using TSMA without significant losses in the RAC mechanical properties, which is recommended for commercial application in structures.Based on the experimental investigations, current RAC models were collected to evaluate the elastic modulus and shrinkage of concrete made with TSMA. These models well matched the experimental results collected from this study and those available in literatures. © 2016, Editorial Office of Journal of Building Structures. All right reserved.