Synthesis And Performance Of Different System Polycarboxylate Superplasticizer

With the rapid development of the construction industry, gradually increase the requirement-s for concrete admixtures in order to meet the different requirements in engineering applicatios,and different types of concrete admixtures have been developed.As concrete admixtures, polycar-boxylate superplasticizers exhibit some excellent abilities of water-reducing, dispersion, slump r-etention, improving the strength of concrete,reducing the cement usage and function controllabe,etc. Therefore, it is meaningful to understand the influence of different functional group in polyar-boxylate superplasticizers. APEG-AA、APEG-MMA-AA、APEG-SMAS-AA、APEG-MAAA and APEG-AM-AA polycarboxylate superplasticizers are synthetized,and their performance and cement hydration rates are discussed in this paper.For APEG-AA polycarboxylate superplasticizers, the water-reducing of APEG monome-r is better than the TPEG monomer;Fluidity increases then drops with the increase of molar rati-o between APEG and AA.And n(APEG) ∶n(AA) =1.00∶3.27 is the best proportion. Fluidity i-ncreases with the increase of activity modulators dosage, and 0.15% by mass of the macromon-omer is the best.Then the fluidity drops. It is found through the orthogonal test that the APEGAA polycarboxylate superplasticizers perform good when reaction temperature is 60℃,reaction time is 4.5h, the dosage of initiator reach 2.0% by mass of the macromonomer. As to the other d-ifferent system polycarboxylate superplasticizers, fluidity increases when the amount of molar r-eplacing of AA、 temperature and time increase,then it drops. And the best the amount of molar replacing of AA is 20%, the best reaction temperature is 70℃, the best reaction time is 4.5h.The technical performance of different system polycarboxylate superplasticizers is tested. S-olid content is 42.7%、39.9%、41.5%、44.3%、41.4% respectively.Mortar water reducing rat-e is 37.6%、38.2%、38.5%、39.4%、37.5% respectively. Saturation point is 0.20%.And the d-ifferent system polycarboxylate superplasticizers show good adaptability to different cement. I nfrared spectra indicates that the functional groups are in the polycarboxylate superplasticizer m olecular structure(-COOH、-O-、-OH、C-H bond,etc).Setting time of cement paste 、strength of mortar and cement hydration rate of different system polycarboxylate superplasticizers are tested. Methyl is of good retarding property. Acylamino is of early strength property. Sulfonic acid and acylamino are of excellent slump-loss retarding.Through the curve of hydration rate, the order of the first peak was: APEG-AM-AA、APEG-AA、APEG-SMAS-AA、APEG-MMA-AA and APEG-MA-AA polycarboxylate superplasticizers.The results matche the results of cement paste setting time and mortar strength.