Synthesis And Performance Of Polycarboxylic Superplasticizers

Development of co-polycarboxylic acid water reducing agent was a modern frontier research project since the 90 years of the 20th century.The poly carboxylic series of water-reducing a gentw asc haracteristic of high water-reducing ratio and preventing concrete mix from slump loss with duration of time.Nowadays, it has become the modem frontier research of high performance water-reducer.In this paper, a kind of water-reduer using polyethylene glycol ether-methyl methacrylate(MPEGMA), acrylic acid, and sodium methylallyl sulfonate as the monomers, high performance water reducer with carboxyl acid groups, sulfonic acid groups and polyoxyethylene side chains were synthesized. Different acid monomers by superplasticizer prepared by line comparison, found that methyl sulfonate type superplasticizer is better than propylene toluene sulfonate, allyl sulfonate class. The impact on the Reaction temperature, feed ratio, feeding mode and initiator dosage to the fluidity of cement grout and the concrete water-reducing rate performance, getting the optimum conditions: At 75℃, with 1.2% ammonium persulfate as initiator, the molar ratio of n (MPEGMA): n (AA): n (sodium methylallyl sulfonate) = 6:8:3 for the ratio, with MPEGMA and AA mix together, dropping over ammonium persulfate and sodium methylallyl sulfonate . Using FTIR spectroscopy to characterize its structure.The effect of feeding mode on product performance was discussed. Influences of the reducer on fluidity of cement paste and water-reducing rate of concrete were discussed. The results show that this water reducer features in low dosage, high water reducing rate,and good performance of concrete. when the content of polycarboxylate type water-reducer is 0.4%, the initial cement paste fluidity is up to 320 mm,the mobile was lost by less than 5% after 2 h,and the water-reducing rate was 30%,compressive strength (28d) increased 42%,bending strength(28d) increased 44%.The polycarboxylic superplasticizer in this study compared with the commercial naphthalene superplasticizer and commercial polycarboxylate by line comparison: water reducing rate, fluidity of cement grout and the mobile lost, strength of cement mortar. The results shows that the polycarboxylic superplasticizer in this study is much better than those two superplasticizer .