Research On The Influence Of Hyperdispersant And Polycarboxylate Superplasticizer On Cement-based Materials

The dispersing property of hyperdispersant lies in some organic pigments and inorganic particles.As one of hyperdispersants,the application of sodium polyacrylate in cement-based materials is limited.It is a typical and fine chemical product produced at home and abroad,and a kind of polyelectrolyte.As a new kind of functional polymer material,sodium polyacrylate has found wide application,and its application varies because of different molecular weight.In recent years,with the in-depth study on hyperdispersant,many new hyperdispersants and their applications have been developed.Therefore,It is necessary to conduct a research of taping its application and to improve the property of cement-based materials with its sound performance.Compared with the traditional water reducer,polycarboxylate superplasticizers exhibit the advantages of high water-reducing rate,cement paste fluidity and low slump loss,etc.In recent years,it attracted many researchers' attention at home and abroad.Taking sodium polyacrylate,cement reducing agent containing sodium polyacrylate and polycarboxylate superplasticizers as research object,this thesis studies the effects of hyperdispersant and polycarboxylate superplasticizers on the fluidity,viscosity and Zeta potential of cement paste,and of self-constriction,drying shrinkage and mechanical property of mortar.Research results show that the sodium polyacrylate and cement reducing agent doping could reduce the fluidity of cement paste and its bleeding,however,the fluidity would rise up when time is prolonged;that cement reducing agent doping could lower the apparent viscosity of cement paste with clay,when polycarboxylate superplasticizer is in here,and it enjoys a sound shear thinning property;that the doping of sodium polyacrylate,polycarboxylate superplasticizer,and cement reducing agent could reduce Zeta potential value of cement paste.The autogenous shrinkage of cement mortar,silica fume cement sand and fly ash cement mortar was reduced by the incorporation of sodium polyacrylate and cement reducing agent;that the sodium polyacrylate and cement reducing agent doping brings no negative influence on the drying shrinkage of cement mortar;that loss rate of water evaporation of cement paste containing sodium polyacrylate and cement reducing agent is lower than that of cement paste without adding anything;that the sodium polyacrylate and cement reducing agent doping brings no negative influence on the fracture and compression resistance of hardened mortar.When added cement dosage of sodium polyacrylate and cement reducing agent containing sodium is 0.1%and 0.6%,respectively,and it is beneficial to improve the later strength of mortar and to enhance the fracture and compression resistance of cement mortar doped with fly ash.