Preparation And Properties Of Non-dispersible Underwater Concrete With Na-bentonite Flocculant

Nowadays more and more Non-Dispersible underwater Concrete(NDC) are used inmodern engineering. Different from ordinary concrete, Non-Dispersible underwaterconcrete is concrete that mixing in a special additives—anti-washout admixture.Propylene (UWB) and cellulose (SCR) tackifier are the most representative ones, of thosemain functions are to increase the treacliness of concrete mixture, so as to achieve theanti-dispersion requirements.This paper is based on the former using Polyacrylamide as the viscosifier ofNon-Dispersible Underwater Concrete, with different dosage in the cement slurry ofNa-bentonite and polyacrylamide, through the cement paste rheological properties test andcement mortar anti-washout performance test, finding the effect on cement pasterheological properties and mechanical properties by adding different mixing amount ofbentonite or polyacrylamide. Through the contrast test, the test aims to find optimaladdition of Na-bentonite as viscosifier in concrete. This is a study of Na-bentonitesubstituted polyacrylamide (UWB) as the basic feasibility of non-dispersible underwaterconcrete viscosifier. In this process, firstly choosing the cement paste as subjectinvestigated, the experiment put the Na-bentonite and polyacrylamide with differentdosage, in order to find out their effect on divergence and rheological properties of cementpaste. Then, on the basis of former experiments, the paper fix Na-bentonite as the optimaldosage, through anti-washout performance test for the new mixed of non-dispersibleunderwater concrete and the strength test for the hardened non-dispersible underwaterconcrete, to further validation feasibility of using Na-bentonite instead of polyacrylamideto reinforce the anti-washout property of non-dispersible underwater in practicalapplication. And ultimately achieve the goal of reducing the cost.Experimental results show that, those two kinds of viscosifier both can significantlyimprove cement slurry viscosity, and existing the optimum dosage in cement pastes. By means of polyacrylamide compared to the market price of Na-bentonite, usingNa-bentonite instead of polyacrylamide is economically feasible, which can reduce thecost of the tackifier. The non-dispersible underwater concrete incorporation ofNa-bentonite has good mobility, and has the characteristics of low fluidity loss, strengthloss, and good dispersion resistance performance. By adding Na-bentonite into thenon-dispersible underwater concrete, the anti-washout property of the cement mortar canbe obviously improved, cement loss and the pH value of water have been decreasedgreatly. The ratios of compressive strength cast in water and in the air are in accordancewith the provisions of the state. This study will provide references and technical supportfor the application of Na-bentonite added in non-dispersible underwater concrete.