Experiment Research Of The Synthesis And Performence Of Polycarboxylate Superplasticizer

In this paper, experiment research of the synthesis and performence ofpolycarboxylate superplasticizer was investigated. The main focuses of this studyand the achievement are as follow：(1) Through the literature review, studying interactional mechanism ofpolycarboxylate superplasticizer and the effects of functional groups, designingmolecular structure of polycarboxylate superplasticizer, and determining the methodof first esterification then polymerization to synthesize superplasticizer, addingsulfonic acid group, ether group, carboxyl group etc. to the molecular structure.(2) Do further research on synthetic technology of active monomer topolycarboxylate superplasticizer. This experiment takes MPEG1200and MAA as themain raw material, synthesizing the activity macro monomer MPEGMA by directesterification. Evaluating the elements which affect the esterification rate and thecontent of double bond comprehensively through the orthogonal test, thusdetermining the optimum process conditions of active monomer synthesis: mole ratioof MAA to MPEG is2.0:1, dosage of inhibitor is2.5%of MAA quality; dosage ofcatalyst is4%of MPEG quality; dosage of water-carrying agent is40%of the totalreactant quality; the reaction time is6h; and reaction temperature is130℃; underthese conditions, the esterification rate is98.9%and the content of double bond is91.1%.(3) Taking APEG1200, MPEGMA as the main raw material, adopting the aqueoussolution polymerization method to synthesize the M-polycarboxylate superplasticizerand A-M-polycarboxylate superplasticizer, determining the optimum technologicalconditions of two superplasticizers by orthogonal experiment. When the mixedquantity is0.3%, the fluidity of cement paste of M-polycarboxylate superplasticizer is275.5mm, the after1h fluidity is271mm; the fluidity of cement paste ofA-M-polycarboxylate superplasticizer is up to270mm and the after1h fluidity is264mm. At the same time，observing the impacts of charging styles, concentration of reactants, the dosage of initiator, reaction temperature and time on the performancesof two superplasticizers. And getting the result that every different element exertssimilar influence on the two superplasticizers.(4) Using two superplasticizers which produced under the optimum technologicalconditions for concrete performance testing, and making comparison with the currentcommercial superplasticizer. The results show that both two superplasticizers havelow mixed quantity, and both of them have good dispersity and the ability of retainingdispersion to the cement. When the mixed quantity is0.5%, the water reducing ratioof M-polycarboxylate superplasticizer is35%; while the water reducing ratio ofA-M-polycarboxylate superplasticizer is30%, they have the similar performance withthe commercial superplasticizer. When the mixed quantity is0.3%,A-M-polycarboxylate superplasticizer’s compressive resistance and tensile strengthprecede M-polycarboxylate superplasticizer and commercial superplasticizer in the1d,3d,7d, and28d age.(5) Characterizing the two superplasticizers with infrared spectrum, it shows thattheir structures are similar, and both of them have sulfonic acid group, ether group,carboxyl group etc. Using scanning electron microscopy (sem) to observe the featureof cement hydrated products, it shows that some hydrated products like ettringite,Ca(OH)2and fibrous gelatin etc. were produced.