基于岛礁环境与原材料的高强珊瑚混凝土制备方法、耐久性与劣化机理

South China Sea Islands is far away from the Mainland，where is no sand and freshwater resources and the environment is harsh. So there has a scientific significance, a national defense and an engineering value for coral aggregate seawater concrete which is casted by mixing and curing method with coral chippings and coral sand as a coarse aggregate and a fine aggregate, respectively, and which is used for the construction of island-reef project, such as a port or an airport, etc. Materials selection routes of coral, coral sand, coral powder and seawater are used in the present project. The mineral admixtures effect of coral powder will bring into full play. And the rich cemented concrete theory and high performance concrete principle are used. So that a high strength coral aggregate seawater concrete which the strength grade is greater than C50 is made. In this way, the consumption of cementitious materials outside the island will decrease and the cost will be lower. The micro-aggregate effect, water-reducing effect, active effect and enhancement effect of coral powder in the coral powder-seawater hydration system will be investigated, and the compound superposition effect of coral powder with other mineral admixtures will be studied in the present project. Besides, the preparation method, mechanical property, corrosion resistance, ion diffusion resistance, long-term mechanical properties evolution and deterioration mechanism of C50 coral aggregate seawater concrete will be investigated and explored in this project. In sum, the aim of this project is to study the basic science issues of island-reef coral aggregate concrete, such as high strength and durability deterioration, etc, and to provide a preparation method of high strength coral aggregate concrete with lower cost and higher durability for island-reef engineering, in order to promote the development of the building materials science.

南海岛礁远离祖国大陆，环境条件恶劣，没有砂石和淡水资源。采用珊瑚碎屑与珊瑚砂作粗细骨料，采用海水拌合与养护方法制备全珊瑚海水混凝土，应用于港口与机场等岛礁工程建设，具有重要科学意义、国防意义和工程价值。本项目充分发挥珊瑚微粉的矿物掺合料效应，采用“珊瑚+珊瑚砂+珊瑚粉+海水”选材路线，借助富浆混凝土理论和高性能混凝土原理，制备强度等级C50以上的高强全珊瑚海水混凝土，并大幅度降低岛外胶凝材料用量。研究珊瑚微粉在水泥—海水水化体系中的微集料效应、减水效应与活性效应和增强作用，以及与其它矿物掺合料的复合叠加效应；研究C50全珊瑚海水混凝土的制备方法与物理力学性能、抗腐蚀与抗离子扩散渗透等耐久性，探索其长期力学性能演变规律与耐久性劣化机理。本项目旨在研究岛礁珊瑚混凝土的高强化与耐久性劣化等基础科学问题，为南海岛礁建设工程提供一种低成本、高耐久的高强珊瑚混凝土配制方法，推动岛礁建筑材料科学的进步。

本项目研究了珊瑚微粉在水泥-海水水化体系中的微集料效应、减水效应与活性效应和增强作用，以及与其它矿物掺合料的复合叠加效应；提出了基于原料属地化新型岛礁海工水泥及高强全珊瑚海水混凝土的制备原理与配合比设计方法，并揭示其长期力学性能演变规律与耐久性劣化机理。结果表明：珊瑚微粉在硅酸盐水泥胶凝材料的水化体系中具有减水效应、活化效应与矿物掺合料效应。珊瑚微粉促进了水化产物成核，促进了C3A水化形成Hc或Mc，并抑制AFt向AFm的转化，从而有利于水泥的强度发展。珊瑚骨料-水泥浆体之间的界面粘结性能与水泥浆体基材性能具有非常显著的线性关系，珊瑚微粉对珊瑚界面结构性能具有明显改善作用，且不受珊瑚微粉掺量的影响。基于在西沙、南沙某岛礁的混凝土暴露站开展不同强度等级的珊瑚混凝土试件/构件的现场暴露实验，以考察其抗海水腐蚀、抗海水冲刷、抗干湿循环和抗大气碳化-盐雾等耐久性，揭示了低强度等级珊瑚混凝土的微结构开裂、腐蚀破坏机理。本项目通过研究岛礁珊瑚混凝土的高强化与耐久性劣化等基础科学问题，为南海岛礁建设工程提供一种低成本、高耐久的高强珊瑚混凝土配制方法，有效推动岛礁建筑材料科学的进步。