Study On Engineering Properties Of Coral Aggregate Concrete In South China Sea

The reefs of the South China Sea are the symbol of China's territorial sovereignty.It is also the base of exploring marine resources,building air and ocean traffic relay station in the South China Sea.In recent years,with the development of the competition for maritime rights and interests,the rights and interests of the South China Sea have been illegally occupied,and it is urgent to start the construction(including military protection engineering)on islands and reefs in the South China Sea,and protect the legitimate rights and interests of our country.This paper focuses on the application background of large-scale concrete engineering,such as wave dissipation blocks,bank revetment,retaining wall and mold bag concrete engineering,etc.According to the technical requirements of the gravity retaining and wave dissipation blocks,the C30 is the target strength of concrete.Considering the finite strength and volume stability,the working mechanism,configuration principle,strength characteristics and durability of coral concrete system are studied.Through the study of this paper,the utilization of coral materials as a kind of engineering material can be improved,and the cognitive level and understanding of the cement-coral system can be developed.In this paper,with reef limestone as coarse aggregate and calcareous sand as fine aggregate,the coral concrete was prepared.Based on the analysis of physical and mechanical properties of coarse coral aggregates,the conceptual model of coral concrete system which consist of coarse aggregate,cement-coral mortar and the transition zone between them is proposed.The configuration principle of coral concrete is put forward,which include increasing the system sand ratio to reduce the internal damage of aggregate;Optimizing the cement content to give full play to the strength increasing effect of cementitious material;Setting workability and durability of concrete are the control index.This conceptual model can be used to guide the design of mix proportion of coral concrete.In this paper,the mix proportion of coral concrete is designed with C30 as the target strength,then the basic mechanical properties are tested.According to these tests,the development of cube compressive strength and splitting tensile strength of coral concrete are analyzed,and the mechanism of the improvement of the tensile strength of coral concrete is revealed.The recommended mix proportion of C30 coral concrete is given,cement:coral sand:coral coarse aggregate(pre-wet):water=1:1.225:0.816:0.32.According to the cement-coral mortar tests shows that the cement-coral system has good compatibility.The regression models of cement-coral mortar between strength and water-cement ratio as well as between strength and sand content is established.It is concluded that the mass ratio of cement to coral sand in coral mortar should not be less than 0.5 to meet the workability and strength requirement.In this paper,the drying shrinkage test and the test which considering the climate environmental factors in the South China Sea of coral concrete are studied.The and temperature shrinkage characteristics of coral concrete are evaluated,and the certain relationship of dry shrinkage between coral concrete and corresponding coral mortar is found,and the regression model of them is given.At last,measures to improve the shrinkage properties of coral concrete are proposed.