Study On The Synthesis And Properties Of Polycarboxylic Acid Type High Performance Water-Reducer With APEG

Polycarboxylic acid type water-reducer which exhibit an excellent ability of water-reducing and prevention of slump loss,represent the trend of warer-reducers for concret in the future.In this thesis the research and application actualities of high performance water reducers both in an outside china were introduced in detail,the synthetic methods and debelopment trends of Polycarboxylic acid type high performance water-reducer was analyzed.Though the molecule design,beginning with the chemical structure and antion mechanisms of high performance water-reducers, polycarboxylic acid type water-reducer which contain,hydroxy carboxyl,sulfonic, polyoxyethylene groups and so on with comb-like molecular structure was synthesized.In this paper,using allyl alcohol polyoxyethylene(APEG),acrylic acid(AA),maleic anhydride(MAD),and Sodium methyl acrylamide(SMAS) as the main raw material.By the radical polymerization,the polycarboxylate acid type water-reducers was synthesized with the using of initiator.The experimental structure indicated that,When monomer APEG:AA:MAD:SMAS mole of ratio 3:4:8:3,this copolymer has the good dispersivity.At the same time the best response condition has been determined:the amount of initiator used for the reactant weight 2%;the reanctant concentrationis 25%;the temperature is 85℃; the reaction time is 4h.The studying of FTIR analysis showed that the molecule structure of synthetic product has the carboxylic groups,sulphonic groups,polyoxyethylene side chain groups. Through gathers the Polycarboxylic acid type water-reducer to the synthesis is reduces water medicinal preparation a series of concrete,the cement experiment,finally indicated the self-restraint gathers polycarboxylic acid type water-reducer have the good dispersivity and the dispersive retentivity.The compatibility between PC with cement is excellent.The configuration concrete has the excellent characteristics such as lower slump loss.The water-reducing ratio in concrete was 32.4% at the solid dosage of 0.3%. the strength ratio was 160%.The properties of PC were obviously superior to FDN,so it can be applied at the concrete profession.Through the studying of surface properties such as surface tension of water-reducer concentration, zeta potential and adsorption capacity of water-ruducer onto cement particles of synthetic product,the water-reducing mechanism was exploited.The results indicated that the water-reducing mechanism mainly depends on the adsorption and dispersion of the interactivity between the polycarboxylate superplasticizer and the cement.On one hand,in the mixed system of superplasticizer,water,and cements,the electric double layer is informed while the polycarboxylate superplasticizer is absorbed on the cement,which generated intra-particle repulsion force.On the other hand,the side chain of the polycarboxylate superplasticizer displays steric hindrance because of extension of longer branched chain.So the dispersion and stability of the dispersion is increased significantly.By analyzing the economic function evaluation,this copolymer have certain function and price advantage,so its future in market is great.