The Preparation Of Marine Concrete And Experimental Study On Application

Since the advent of cement concrete materials,more and more scholars have carried out research on its application technology.The 21 st century is the century of the ocean,marine resources have been increasingly exploited,marine concrete structures also developed.Different from the terrestrial environment,there are a lot of harmful substances in the marine environment,they will pass through the concrete protective layer around the steel and destroy the passive film on the steel surface,which results in the decrease of the bond strength between steel and concrete,and is not conducive to the long-term durability of marine structures,and once the marine structure damaged,it is extremely difficult to repaired.In view of the factors such as resources,economy and security,improve the long-term durability of the concrete structure has become a focus in the study of civil engineering,research on durability of cement concrete is also particularly important.In this paper,with fly ash,mineral powder and silica fume as mixed material,through the experiment of the physical property of cement mortar,the impermeability test,the sulfate resistance test and the chloride diffusion coefficient test and so on,to developed a good durability of marine cement.With metakaolin,ground quartz sand,waste silicon powder and floating beads as mineral admixtures,and used with Chemical additive-Water reducing agent,through the concrete working performance experiment,compressive strength experiment and chloride ion diffusion coefficient,determine the best proportion of mineral admixture and chemical admixture and the appropriate admixture of admixture.The main research work and achievements are as follows:Chloride ion is the main cause of steel corrosion,Therefore,it is necessary to strictly control the content of chloride ion in concrete.Analysis the chemical composition of the fly ash,slag,silica fume,metakaolin and waste silicon powder,quartz sand,floating beads respectively,selection the raw materials that chlorine-free raw materials or chlorine ion content is less than 0.06%.For the prepared marine portland cement,gypsum has good retarding and strengthening effect.Under the condition of CH,gypsum generates a microexpansion by the hydration reaction consuming CH to generate AFt,not only can improve the strength of the cement system,but also can reduce the porosity,improve the density of cement systems,effectively prevent the harmful material in the external environment.The results showed that the optimum content of gypsum is 7%,when the amount of gypsum is too high,due to the formation of AFt,the expansion rate is too large,resulting in the micro cracks in the cement system,adversely affect its strength and durability.Silica fume is high activity superfine powder,on the one hand,it can participate in the hydration reaction to produce cementitious material and improve the strength of cement system,on the other hand,give full play to the role of physical filling,reduce the porosity of cement system,improve the density.The results showed that the optimum content of silica fume is about 4%,when the amount of silica fume is too high,the content of CH that reaction required is not enough,excessive silica fume plays a major role in physical filling,and the effect is not obvious on the improvement of the strength and durability.Fly ash and mineral powder are commonly used in cement industry,and has a high activity,in addition,the micro-morphology of fly ash is glass beads,it can play a role in lubrication,and improve the performance of cement concrete.The results showed that the content of fly ash should not exceed 16%,and the content of mineral powder is about 40%,the physical properties and durability of marine cement prepared by this method can meet the national standard of marine cement.The study of marine concrete admixtures showed,with metakaolin,quartz sand,waste silicon powder and floating beads as raw material,according to the ratio of 1:1:2:2 made of concrete mineral admixture,the marine concrete has good working performance,high compressive strength and low chloride diffusion coefficient,and good durability.With poly carboxylic acid water reducing agent as chemical admixture,mixed with mineral admixtures,the prepared marine concrete has excellent adhesion performance,water retention performance and work performance,high compressive strength,low chloride diffusion coefficient and good durability.