| High-performance water-reducing agent is one of the key technologies to the preparation of HPC. Polycarboxylate Superplasticizer with a high water reducing ratio, good concrete-slump-lost controlling ability (good dispersibility and holding dispersibility) and environmental friendliness, etc., is the preferred water-reducing agent, and its synthesis technology is the current major research focus. Starting from"anhydrous esterification"of maleic anhydride,obtained high activity of unsaturated open-chain hydrocarbons esterifiable big monomer,based on low efficient catalyst method , and synthetize solid content up to 75% of polycarboxylate superplasticizer ("improved PC") using special redox initiator at 40℃.In the esterification of maleic macromonomer synthesis, reacting the maleic anhydride (MAn) with different molecular weight polyethylene glycol monomethyl ether by using the self-made solid catalysts according to a certain percentage under the condition of low-temperature and non-nitrogen. By orthogonal design experiments, analyzing the nuclear magnetic resonance spectroscopy based on the diagram to determine the best conditions for the esterification: n(MPEG)∶n(MAn)= 1:2.5, catalyst dosage is 1.6%(MPEG Wt%), inhibitor dosage is 0.3%(MAn Wt%), reaction at 75℃under 5 hours. Under the best conditions the esterification rate can get 95%, while controlling the rate of double bond for the remaining 95%.In the radical polymerization reactions, combine with IR and NMR spectra, from the trigger mechanism of the system to start, and then compare with ammonium persulfate and redox initiator system, the initiator dosing methods, dosage, and discuss the reaction temperature, reaction time and the system of concentration on the copolymerization reaction were systematic investigated. For sodium formaldehyde sulfoxylate- hydrogen peroxide redox system, the copolymerization of polymerization monomer residual rarely, solid content is as high as 75%.The application of traditional PC(ammonium persulfate initiator system at reaction temperature 90℃~95℃) and modified PC in the pumping concrete was explored,focus on compatibility problems of water-reducing agent in concrete application. In the same concrete mix, compared to traditional PC, the modified PC has a stronger advantage on workability of fresh concrete and mechanical properties of hardened concrete, while able to effectively reduce the amount of cement, reduces costs and improves overall performance of concrete. Besides, the compatibility of modified PC with expansion agents and different kinds of cement is good. As clay / powder dosage increases, water requirement increases,slump losses increase, but early compressive strength gradually reduces. Through infrared spectroscopy it is discovered that adsorption of powders on modified PC, mud>cement> stone powder, which is consistent with macro test results.Finally, the Preparing of powder polycarboxylate superplasticizer by centrifugal spray drying process are discussed in this paper and the powder solid content can reach 99%. Based on single factor experiments, the major parameters affecting the drying process are discussed and the appropriate process conditions were obtained such as the import air temperature of drying chamber must be controlled at 180℃~220℃;the spray-drying feed temperature controlled at 20℃~40℃, and the concentrations of liquid polycarboxylate superplasticizer are in the range of 20% to 60%. With calcium carbonate and dosage of 2% as resistance agent, powder has good dispersion and good stability. Through infrared spectroscopy it is discovered that the carbonyl group were partly decomposed during the drying process, but the obtained powder's performance were limited impacted thus its performance is at the same level compared to the liquid superplasticizer.
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