Study On Properties Of Non-Dispersible Underwater Concrete

Social economy develops rapidly,but it brings about shortage of resource,especially land space resource. Human beings begin to explore new energy resource and space resource from coastal waters and river. Concrete become the preferred building materials in underwater engineering, because of its advantages: raw materials are cheap and easy to get, it’s very convenient to make construction members of any shape, and its strength and durability are very good. But the environment underwater is different from it on the land: concrete will be affected by water erosion underwater; the erosion of ions in seawater is more serious than the erosion of fresh water on the concrete. The non-dispersible underwater concrete could be able to place successfully in water environment, which has been applied in construction at present. But the prosperities of harden non-dispersible underwater concrete remain to be studied further and improved, especially in the seawater environment.In the experiment, non-dispersible underwater concrete samples are made in three conditions: on the land, in fresh water, in seawater. The mechanical property and durability of non-dispersible underwater concrete are tested to study the law of different placing means and mineral admixtures affecting on property of non-dispersible underwater concrete.First of all, 11 groups mix proportions of non-dispersible underwater concrete is designed by means of calculation and test. The non-dispersion and the mobility of non-dispersible underwater concrete are tested, and the results show that the non-dispersion and the mobility of non-dispersible underwater concrete with fly ash and silica fume together are both preferably.Secondly, test of compressive strength and splitting and tensile strength of non-dispersible underwater concrete are took, which are placed in different means and added with different mineral admixtures. The results showed that the strength of non-dispersible underwater concrete sample placed on land is higher than that of sample placed underwater, and the strength of non-dispersible underwater concrete sample placed under seawater is higher than that of sample placed under fresh water in early age, but lower in long-term age. There is no new crystalline product but only more AFt in cement hydration process under seawater, which is more favorable to the early strength of concrete. Only mixing fly ash or ground granulated blast furnace slag is harmful to the strength of non-dispersible underwater concrete, only mixing silica fume is helpful to the strength of non-dispersible underwater concrete, and degree of improving the strength of non-dispersible underwater concrete is moderate by mixing fly ash and silica fume together.Finally, chloride ion diffusion coefficient of concrete samples, weight loss and relative dynamic modulus of elasticity of concrete samples after freezing and thawing test are all tested. These samples of non-dispersible underwater concrete are made with different placing means and mixed with different mineral admixtures, too. The experimental results show that: without mixed mineral admixtures, property of resistance to chloride ion penetration and antifreeze property of non-dispersible underwater concrete samples placed on land are better than those of concrete samples placed under water, those of concrete samples placed under seawater are the worst. After mixed with mineral admixtures, property of resistance to chloride ion penetration of non-dispersible underwater concrete is improved, especially only mixed with silica fume and mixed fly ash and silica fume together have the most significant effect. Mixed with fly ash is harmful to antifreeze property of non-dispersible underwater concrete. Only mixed with silica fume and ground granulated blast furnace slag separately could improve the antifreeze property of non-dispersible underwater concrete, and the effect is best. Mixed with silica fume and fly ash together or mixed with ground granulated blast furnace slag together also could improve the antifreeze property of non-dispersible underwater concrete, but the effect is moderate.