碳化再生骨料水泥混凝土道面的疲劳特性及细观机理研究

With the development of airport runway renovation and expansion, more and more waste concrete will be generated due to the demolition of old pavement. It is a sustainable approach to use the waste concrete to make recycled concrete aggregate. However, it is an obstacle to implement the recycled concrete aggregate in airfield pavement construction because of its’ high porosity and low strength. Thus, the applicant proposed the method of carbonation for enhancing the property of recycled concrete aggregate. Since the airfield pavement structure design relies on the fatigue design theory, the implementation of carbonated recycled concrete aggregate in airfield runway renovation and expansion needs to clarify the influences of carbonated recycled concrete aggregate on the fatigue property of concrete pavement. This research will perform multiple scale tests and numerical simulation to investigate the meso-structure and mechanical property change of recycled concrete aggregate during carbonation, and establish the relationship between the formatting and features of interfacial transition zone and fatigue property. Then, reveal the influencing mechanism of carbonated recycled concrete aggregate on the fatigue property of concrete, and analyze the meso-mechanical change characteristics and fatigue failure criterion of carbonated recycled concrete under repeated loading. In the end, the simulation results can be evaluated and modified based on reduced scale test, and the fatigue life prediction model of concrete pavement with carbonated recycled concrete aggregate can be obtained. Findings from this research can provide theoretical basis for implementation the carbonated recycled concrete aggregate in airfield pavement project.

随着机场道面改扩建规模的持续增长，因旧道面破除产生的废弃混凝土越来越多，用废弃混凝土制备再生骨料是机场铺面工程实现可持续发展的重要举措之一。然而，再生骨料由于孔隙率大、强度低，导致其在机场铺面工程中的应用受到严重制约。为此，申请人提出碳化改性再生骨料的方法。考虑机场道面结构设计主要基于疲劳设计理论，碳化再生骨料在机场道面改扩建中的应用需要明确其对水泥混凝土道面疲劳特性的影响。本项目拟通过多尺度试验和数值仿真模拟，研究再生骨料的细观结构与力学性能随碳化过程的变化规律，建立界面过渡区的形成和构造特征与疲劳特性的内在关系，揭示碳化再生骨料对水泥混凝土疲劳特性的影响机制，分析重复荷载作用下碳化再生骨料水泥混凝土的细观力学变化特征与疲劳破坏准则；最后，通过缩尺试验对仿真结果进行校验与修正，得到碳化再生骨料水泥混凝土道面的疲劳寿命预估模型。研究成果可为碳化再生骨料在机场铺面工程中的应用提供理论依据。

再生骨料由于其粘附的水泥浆体具有孔隙率大、强度低等问题，导致其利用效率受到严重制约。近年来，碳化改性成为提高再生骨料品质的一种新方法，本项目从碳化对再生骨料细观结构的影响、碳化再生骨料细观结构的表征、碳化再生骨料水泥混凝土的仿真重构与疲劳特性表达，以及碳化再生骨料水泥混凝土道面疲劳特性的细观机理四方面开展系统研究。项目明确了再生骨料的细观结构与力学特性随碳化程度的变化规律，揭示了碳化再生骨料水泥混凝土界面过渡区的形成机制以及界面过渡区对水泥混凝土疲劳特性的影响效应，建立了细观结构变化特征与宏观疲劳性能的内在联系，构建了碳化再生骨料水泥混凝土的仿真模型，研究了重复荷载作用下碳化再生骨料水泥混凝土的细观力学变化特征与疲劳破坏准则，并结合缩尺试验与传感器感知技术，对仿真结果进行校验与修正，得到了碳化再生骨料水泥混凝土道面疲劳寿命预估模型。研究成果为未来机场改扩建项目中大面积推广和利用废弃混凝土提供解决方案。