Preparation And Performance Study Of Polycarboxylate Water-reducing Agent

Superplasticizer is a very important class of concrete admixtures, which can greatly reduce the limits of the concrete water-cement ratio, improve the strength and durability of concrete. superplasticizer is essential for the development of green and Efficient concrete. Superplasticizer with a comb-shaped molecular structure, is a new type of superplasticizer, compared with the second generation of naphthalene and melamine series such as water-reducing agent, which has a low ash, high water reduction High security collapse, low slump loss, low alkali content, and cement adaptability, production and use of clean energy and other advantages. Superplasticizer is a high strength and high fluidity concrete, high volume fly ash concrete is an important component of the material. Research and development of new superplasticizer caused widespread concern at home and abroad.However, the preparation of high-performance superplasticizer on the premise that excellent performance prepared intermediates.Currently, synthetic polycarboxylate superplasticizer class methods are macromonomer method, macromolecular reaction and graft in situ polymerization method, which macromonomer method is a more common method, This is the method of polymerization after the first esterification, i.e. firstly prepared by esterification of the macromonomer in a polymerization activity (usually mPEGM A), then a certain ratio of macromonomer were mixed together, the application of the solution polymerization get superplasticizer.By methacrylic acid and methoxy polyethylene glycol esterification, preparing a Polycarboxylate superplasticizer reactive intermediate macromonomers-methoxy polyethylene glycol methacrylate. We studied the effects of various experimental conditions on the esterification reaction and the optimum conditions which obtained macromonomer. Then synthesized superplasticizer, explored the impact of various factors on the performance of superplasticizer. The main contents of this paper are as follows:(1) We synthesis polycarboxylate superplasticizer middle class macromonomer. Esterification rate is metrics, by contrast experiments and orthogonal experiments we received influence of molar ratio, catalyst polymerization inhibitor dosage, reaction temperature and time on the esterification reaction, so obtained the optimum conditions.(2)We use homemade relatively stable polycarboxylate superplasticizer middle class macromonomer synthesis superplasticizer.Then studied the effects of salt, acid, acrylic esters, reaction time and temperature on the paste fluidity,thereby improving and reducing the slump loss.When ammonium persulfate (APS) used in an amount of 6.4% and AA/MAA molar ratio of 2.45, superplasticizer achieve the best dispersion.(3) We studied Polycarboxylate (PCA) with ordinary water reducer SAF (aliphatic), FDN (naphthalene) Cement drying shrinkage and water rates,through performance testing cement superplasticizer Characterization superplasticizer performance differences. Through performance of cement superplasticizer,we characterize the difference in performance superplasticizer.