海洋既有建筑再生骨料及海洋再生混凝土的性能研究

为促进海洋环境中既有建筑混凝土的循环利用，推进建筑行业可持续化进程，在浙江省宁波市与舟山市采集废弃混凝土构件，测试其抗压强度及游离氯离子含量，利用压汞仪分析其孔隙结构。将海洋既有建筑混凝土破碎成再生骨料，测试其物理力学性能及颗粒形态。采用海水与再生骨料制备海洋再生混凝土，测试其抗压强度及劈裂抗拉强度，利用扫描电镜与X射线衍射仪分析其微观形貌及组成。研究结果表明：受局部环境的影响，海洋既有建筑混凝土的宏微观性能具有较大离散性，性能较差的海洋既有建筑混凝土，破碎成的再生骨料品质也较差，主要表现为表观密度较低，吸水率及压碎指标较高。即使再生粗骨料与再生细骨料取代率达到100%，海洋再生混凝土强度等级也可达到C40~C45，由于原材料就地取用率较高，海洋再生混凝土具有潜在的环境效益和经济效益。

Study on properties of recycled aggregates made from existing marine structures and performance of marine recycled concrete

In order to promote the recycling of concrete from existing marine structures and the sustainable development of the construction industry, the waste concrete members were collected from Ningbo and Zhoushan in Zhejiang Province. The compressive strength and free chloride ion content were tested. The pore structure of specimens was analyzed by mercury intrusion method. Then the concrete was crushed into recycled coarse aggregates and recycled fine aggregates. The physical and mechanical properties, as well as particle morphological characteristics were comprehensively studied. Moreover, the marine recycled concrete was prepared using the simulated seawater and recycled aggregates. The compressive strength and splitting tensile strength were tested. The microstructure and composition were analyzed by scanning electron microscope and X-ray diffraction. The results show that the macro and micro performance of the existing marine concrete is rather discrete due to the influence of local environment. The worse the performance of the existing marine concrete, the worse the qualities of the recycled aggregates, which are characterized by lower apparent density, higher water absorption and higher crushing index. Even if the replacement rates of the recycled coarse aggregates and recycled fine aggregates are up to 100%, the strength grade of the marine recycled concretes is possible to reach C40-C45. Due to that most of the raw materials are able to be obtained locally, therere potential environmental and economic benefits to prepare marine recycled concrete.