5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的碳化促进养护

ACCELERATED CARBONATION CURING OF 5% ETHYLENE/VINYL ACETATE COPOLYMER MODIFIED LOW HEAT PORTLAND CEMENT PASTE

采用碳化养护方法促进5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的水化。通过X射线衍射定性及定量分析测定了养护后样品的组成及水泥中硅酸三钙(3CaO·SiO2,C3S)、硅酸二钙(2CaO·SiO2,C2S)的水化率;利用带固体样品测试装置的全有机碳素分析仪测定了样品所吸收的CO2量;采用水银压入法检测了样品的孔径分布。结果显示:碳化养护大大促进了低热水泥的水化,并有球霰石生成。样品中的总孔隙体积也明显减少,但有大量较大孔径的毛细孔隙存在。碳化养护前,对样品进行水中预养护可以减少这些毛细孔隙,但不利于水泥的水化并导致CO2吸收量及抗折强度显著降低。

Carbonation curing was adopted to accelerate the hydration of low heat portland cement （LHC） paste modified with 5 % ethylene/vinyl acetate copolymer（EVA）. The phase composition and the hydration rate of C3S and C2S were tested by X-ray powder diffraction and quantitative analysis. The amount of absorbed CO2 was measured by a total organic carbon analyzer equipped with a solid sample module. The pore size distribution was determined with mercury intrusion porosimetry. The results show that hydration of LHC is greatly accelerated by curing in CO2, accompanied with the formation of vaterite. The total pore volume of the paste decreases considerably after curing, but a significant number of larger capillary pores remaines. These larger capillary pores are reduced by precuring in water before carbonation curing; however, it leads to a low hydration rate of the cement, and results in a remarkable decrease of both the amount of absorbed CO2 and the bending strength.