Research On Coal Series Water Reducing Admixture And Properties

Concrete admixtures are indispensable components in concrete. Water reducing agent is the available part,and it's progress can reflect the application and development level of concrete admixtures.This article does some researches on one kind of superplasticizer named NES considering problems in the ues of concrete,such as the dissatisfactory quality,high cost, and instability of volume.This article highlights the chemical procedure and the properties of the cement and concrete with NES. Lignite is oxidative degraded by nitric acid for increasing content of humic acid, and is created nitro-group for accelerating sulfonation;after extraction by sodium hydroxide,chemical agent named A is used as sulphonating agent for increasing dispersion of nitro humic acid on cement in sulfonation reaction.Orthogonal tests are used in oxidative degradation reaction and sulfonation reaction for selecting optimum.Nitro humic acid is sulfonated directly without filtration after extraction for shortening technological process. Compared with NE from oxidative degradation,ES from sulfonation after extraction and NES,the cement paste divergences of the formers are less than NES. So it is proved that oxidative degradation reaction is necessary to increase the content of humic acid,and sulfonation reaction can increase the cement paste divergence of humic acid.When adding NES into cement,it can improve the cement paste divergence,accelerate cement hydration,densify hardened cement structure,enhance the compressive strength at early stage,entrain small pore,and improve hardened cement structure.The water reducing ratio of concrete is approximately at 15%;the initial setting time is delayed,and the final setting time is ahead of time basically;the compressive strength of concrete is enhanced;the rates of shrinkage are smaller than the reference concrete.The technological process of NES is short,energy consumption is low,and the production is pollution-free.The combination property of NES is well.The effect on cement and concrete is significant.