Study On Synthesis Of Polycarboxylate Superplasticizer

The paper research that polycarboxylate superplasticizer are introduced into ether, sulfonic, amide, carboxyl group as side chains, greatly enhancing its performance which contain water educe, slump, enrained air, autostability and so on. The experiment is based on methylallylpolyethenoxyether(HPEG),2-acrylanmido-2-methylpropa-nesulf-onic acid(AMPS), acrylic(AA) as main material, researching effect on factors which comprise the ratio of reactants, the dosage of initiator, the reaction time and temperature during reaction. Through orthogonal experimental design, the best reaction conditions was optimized though orthogonaltable L9(3), the result show that the optimum parameters is reaction T=60℃, reaction time4hours, n(HPEG):n(AA):n(AMPS)=1:3.5:1, the dosage of initiator2%, n(HPEG):n(AA):n(AMPS)=1:3.5:1.The functional groups of polycarboxylate superplasticizer are confirned by FR-IT, the molecular weight are determined by GPC,the molecular of Mn=64450g/mol, Mw=83220g/mol.The property measurement of product show that the flowability of cement paste will attain295mm and the water reducing rate is30%on the condition dosage of0.3%, w/c=0.29. Meanwhile under the different temperatures:T=30℃, T=40℃, T=50℃; the absorption ability of polycarboxylate superplasticizer are researched by establishing the Langmuir model make use of Linear fitting calculating maximum adsorption, that is absoption dosage is6.25mg/g,7.44mg/g,8.06mg/g. The rate constants of frist-order and second-order kinetics, Correlation coefficient R2are fitted by Origin8.0on based of kinetics equation models. The result show that the rate constants and R2will greatly raise with the temperature raise. In addition, shape and elment of hydration products are analysed by SEM and EDS after the adsorption, deeply research some principle, which effect on crystal growth in different temperature. Meanwhile, on the different curing time3days,7days,28 days, the hydraion pruducts of cement are researched by using of XRD. The result show the diffraction peak of CH are stronger, comparing the adding PC to cement to blank of cement; Those implie that the polycarboxylate superplasticizer promote the hydrated reaction of cement.However, In the process of synthetize polycarboxylate superplasticizer need heating, which is not only leading to the low solid content, but also increase cost in transportation. In order to solve this problem, the experiment adopt redox system as initiator based on synthetic technique, and discuss some factors which include the ratio of reducing substances, the dosage of oxidizing agent and initiator, the adapation and resting period of initiator. In addition the experience result show that the ratio of reducing mater, the dosage of oxidizing agent and initiator are3/4,1%,4%. Under these conditions, synthetized polycarboxylate superplasticizer is basied on the optimum ratio of reactants parameters through comparing the property with kind of water reduce, the result show performe reasonably. Polycarboxylate superplasticizer are successfully synthesized at room temperature.The water reduce applied in concret, have worse competability. The study is mainly solving this disadvantage through the product performance by addition of molasses and calcium lignosulphonate; The experiment conclude that compound water reduce have good performance in the use of molasses5%and calcium lignosulphonate5%.