Research On High Performance Marine Underwater Concrete

The 21st century is marine cent, with the marine resources mass exploitationed, underwater projects become more and more, Due to poor erosion resistance, poor rheological property and poor resistance to seawater corrosion, the common concrete can not meet the needs of marine engineering. Underwater Concrete (UWC) has been paid more and more attention by the engineering field because of its good resistance to erosion, high water surface strength, water and self compacting, The research focus on the field of concrete research, focusing on the UWC composition, working performance, mechanical properties and durability, etc., to provide reliable technical support for the engineering application of UWC.The paper first do some research on the basic performance of the underwater concrete anti dispersion agent and analysis it’s compatibility of the mixture with the poly carboxylic acid water reducer. then based on the literature and the research results, and summarized the design method of mix proportion design of high performance underwater non dispersed concrete. And using single factor rotation method to study the change law of the concrete fluidity, anti dispersion and strength of the concrete Influenced by the main influence factors, such as water binder ratio, anti-washout admixture dosage, sand ratio, dosage of water reducing agent, etc., based on C40 anti-washout underwater concrete mix ratio,thus obtain the optimal concrete mix ratio. Last, also study on the influence of fly ash, slag powder and silica fume single doped or double mixing even three mixed on the fluidity, anti dispersion, strength and anti chloride ion permeability based on the optimal mix proportion, revealed the main influence factors and influence law of the performance of non dispersible under water concrete.Using the cement paste as a carrier, study the effects of the amount of anti dispersion agent on the fluidity and dispersion of the slurry and the compatibility of the anti dispersion agent and the high efficiency water reducing agent. When the mixing amount of the anti dispersion agent is less than 1.5%, the fluidity of the slurry is increased with the increase of the amount of the dispersant, when the content of the anti dispersion agent is over 1.5%, the fluidity of the slurry is obviously decreased, anti dispersion agent dosage is 0%-3.5%, slurry body through the water layer the pH value of water and water turbidity were reduced linearly, viscosity and shear stress increase linearly. By the combination of anti-dispersing agent and water reducing agent, the fluidity of the slurry can be significantly improved, shear stress and viscosity decreased.Results show that the high efficiency water reducing agent and the anti-dispersing agent have good compatibility.Water cement ratio can increases the fluidity of concrete, but it is bad for the anti dispersion and strength of concrete. Anti-dispersant agent can improve the strength and anti-dispersion of concrete significantly, but it is bad for the mobility; In a certain range, the increase of sand ratio can improve the fluidity of concrete.,when the sand ratio is too large, the dispersion of concrete is slightly enhanced,but the flow of concrete is poor, and the strength is reduced; With the same amount of water consumption, the high efficiency water reducing agent can effectively improve the fluidity of concrete, but it can reduce the dispersion and strength of concrete, therefore, the amount of water reducer can not be too large.With concrete fluidity, dispersion and strength for test indicators, studied the effect of mineral admixtures on underwater concrete performance. In the range of test content, fly ash and slag can improve the liquidity of concrete when only mixed, To a certain extent reduce the concrete anti dispersion at the same time, when mineral slag single doped concrete early strength changed not much, but the later strength was significantly improved. When mixed with fly ash and slag can play a "strength complementary effect", both early and late strength of concrete were improved, at the same time, the anti-dispersion of concrete is better than that of single doped. The anti dispersion property and strength of concrete can be significantly improved by adding silica fume into concrete,and when the content of silica fume less than 6% concrete liquidity has a certain improvement effect.Using chlorine ion electric flux as evaluation standard, study on the influence of fly ash, slag powder double mixing and fly ash, slag powder, silica fume three mixed on the anti chloride ion permeability of concrete under water, Research shows:when fly ash and slag powder double mixing concrete electric flux of concrete was significantly smaller than single doping, and the longer the curing period of concrete electric flux is low. concrete electric flux decreased sharply after adding silica fume, when 56d age the concrete electric flux are lower than the 700C, permeability level is "very low".