Development Of Polycarboxylate High-performance Superplasticizer

Polycarboxylate high-performance superplasticizer(PC) is currently growing moreimportant and enflencial and is representing the trend of the future water-reducerdevelopment due to its high water-reducing ability and remarkable slump loss controlability etc. In this paper, develop history、structural features and function mechanismof PC is systematically introduced, and a new kind of PC called Z-PC is succesfullydeveloped with its process parameters and conditions studied and performace indextested.In the tests, PEG and AA is selected as the main reaction material、H2SO4(98%) asacid catalyst and phenothiazines as inhibitor, and all the materials are compoundedtogether to produce target product PA by way of direct esterification. As the tests havegave out, the most preferable process parameters and condition is: PEG-23:AA=1:2.5with dosage of H2SO4equivalent to0.5%of weight of AA and PEG-23, dosage ofphenothiazines maintained0.1%of PEG-23’S weight and reaction tempreture andtime kept with85℃and4-5hours respectively.Z-PC is made by means of free radical polymerization with main reaction materialsPA、AA and MSA, free radical polymerization (NH4)2S2O8and chain transfer agentBmercaptothanolB mixed together in water sovlent. As the resluts showed, the bestprocess parameters and conditio is: Solution concentration is20%,MSA:PA-23:AA=1:3:6with dosage of (NH4)2S2O83%of the whole materials’weight, reaction tempre-ture and time be hold whin70℃and5hours respectively and the PH of raw productis required to be adjusted to7using30%NaOH standed solution. It turns out thatMSA and AA have much effect on dispersal property of water-reducer while thelength of PA chain play a more important role in its dispertion-loss-kept property.Zeta-electric-potential tests indicate that self-made water-reducer Z-PC command agood control of cement paste fluidity; Infrared spectroscopy tests show that suchfunction groups as carboxyl、ester、hydroxy、－PEO and sulfo is introduced as isexpected; And according to GPC analysis, polymer with large molecular weight is found in Z-PC with a little residual reaction monomer remained.Performance tests show that chemical properties and uniformity of Z-PC meets theneed of national standard, saturated dosage of Z-PC is2.0%、recommended dosage is1.2%and maximum water reducing ratio can reach35%, integrated performance ofconcrete with1.2%Z-PC is close to that of1.1%GLENIUMSP-8CN and is superiorto that of1.5NF.