| In order to improve the compatibility of the polycarboxylate superplasticizer with the mineral additive,the silane copolymerized modified PCE prepared by the copolymerization of vinyl-containing silane coupling agent containing vinyltrimethoxysilane(A171)and ?-methacryloxypropyltrimethoxysilane(KH570)with the binary polycarboxylate superplasticizer(PCE).The effect of silane modified PCE on the rheological behavior of cement paste,cement-fly ash slurry and cement-silica slurry was investigated.The influence of silane modified PCE on the hydration process of cement paste,cement fly ash paste and cement silica paste was studied,and the influence of mechanical properties on cement hardened mortar was compared and analyzed.The results are as follows:(1)The KH570 series copolymerized polycarboxylate superplasticizer(KH-PCE)was synthesized.The molecular weight range and chemical composition of the KH-PCE series were characterized by intrinsic viscosity and infrared spectroscopy.The effect of such factors as dosage of chain transfer agent and reaction time on the products' capacity are discussed,and the synthetic experimental conditions were optimized.The influence of KH-PCE on the rheology of cement paste was studied.And the influence KH-PCE to the mechanism of initial hydration of cement and the mechanical properties of hardened mortar were discussed and analyzed.The application of KH-PCE in cement-fly ash slurry was investigated.The results show that KPCE0.5 and KPCE1 have good resistance to sulphate,which can improve the initial fluidity of cement slurry,prolong the setting time,inhibit the formation of hydration products in cement hydration early,increase and harden the compactness of the structure of cement,and improve the resistant ability of hardened mortar to compress and bend.However,when the molar ratio of KH570 in PCE is too high(KPCE1.5,KPCE2),it is easy to form polycondensates by hydrolysis in cement slurry,which adversely affect the performance of cement slurry.KPCE1 is used in cement-fly ash slurry,which show good adsorption capacity such as promoting fly ash particles dispersion and improving the initial fluidity and the setting time of cement-fly ash slurry.The effect of chemical combination water content on hydration products in 3 days and 7 days was small,but it could increase the content of chemical combination water of hydration products in 28 days,and promote the reaction degree of fly ash in cement hydration.(2)The A171 series copolymerized polycarboxylate superplasticizer(A-PCE)was synthesized.The synthetic conditions were optimized on the basis of results of A-PCE intrinsic viscosity and infrared spectrum analysis.The influence of A-PCE on the rheological properties of cement paste was investigated.The influence of A-PCE to mechanical properties of hardened mortar and its application in cement silica paste were discussed.The results show that A-PCE can improve the setting time of cement slurry and reduce the loss of fluidity.The pictures of SEM display that A-PCE can reduce the size of cement hydration products,enhance and harden the density of structure of cement,and improve the resistant ability of hardened mortar to compress and bend.The A-PCE was applied in cement-silica slurry,which could decrease the loss of fluidity of cement-silica paste,increase the content of chemical binding water of cement-silica slurry for 3 days,7 days and 28,reduce the amount of hydration process of calcium hydroxide,and improve effectively the resistant ability of cement-silica mortar to compress and bend.(3)The ASPCE series products was prepared by introducing modified silica A171 into the molecular structure of polycarboxylate superplasticizer by polymerization.The application performance of ASPCE in cement slurry was discussed.The ASPCE significantly reduced the fluidity of cement slurry and the setting time,enhanced the compactness of hardened cement structure,improved the mechanical properties of hardened mortar. |
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