Abstract:Modified polycarboxylate superplasticizer (MPC) was synthesized by free radical copolymerization of acrylic acid (AA), methyl acrylic acid sodium (MAS), β-cyclodextrin grafted maleic anhydride (MAH-β-CD) and methylacrylic acid polyethylene oxide ether (APEG) using ammonium persulfate [(NH4)2SO4, APS] as initiator. Effects of mole ratio of reactants, dosage of initiator, reaction temperature and reaction time on the properties of superplasticizers were investigated. The optimum MPC was synthesized when the molar ratio of n(AA) : n(MAS) : n(MAH-β-CD) : n(APEG) were 5 : 0.5 : 0.1 : 1 using 5 wt% APS at 90 °C for 5 h. The application results show that the fluidity of cement paste can reach 306 mm, the initial setting time is 440 min and the water reducing ratio is 32.2 %. SEM and compressive strength results show that the microstructure of hardened cement doped with MPC are more homogeneity and the porosities are smaller, which are benefit for the development of later structure of concrete.