聚合物涂层对混凝土碳化的影响及作用机理

Influence and mechanism of polymer coating on concrete carbonization

为了提升混凝土的抗碳化性能,在混凝土表面涂覆了一层聚合物防护材料.通过碳化试验,并采用热分析仪、图像分析技术及压汞法,对比研究了聚合物涂层涂覆后混凝土碳化性能的变化,分析了涂层材料的使用引起水泥石水化程度、表面微裂纹及毛细孔结构改变对碳化反应的影响.实验结果表明,涂覆聚合物涂层的混凝土试件7d碳化深度与基准组相比降低了20%.涂层材料的使用增加了水泥石中C-S-H凝胶及Ca(OH)2可碳化物质的量,但降低了单位时间内可碳化物质消耗量与生成总量的比值,从化学层面延缓了水泥石的碳化.聚合物涂层抑制水泥石表面裂缝的产生,减少大于100nm毛细孔数量并降低总体孔隙率,使水泥石抵御CO2气体侵入的能力提升,增强了水泥石的抗碳化能力.

The carbonization resistance of concrete is enhanced by coating a layer of polymer protective material on the surface of concrete.The carbonization property of concrete coated with polymer is investigated by the carbonation test.The effects of hydration degree,surface micro-crack and pore structure changes in cement paste caused by coating with polymer on carbonization of harden cement paste are analyzed by thermal analysis,image analysis and the mercury intrusion method.The results show that the carbonation depth of concrete coated with polymer reduced by 20% compared with normal group without polymer coating at 7 d.The amounts of readily carbonizable substances in harden cement paste such as C-S-H gel and calcium hydroxide increase after coating with polymer.But polymer coating reduces the ratio between readily carbonizable substances consumption per unit time and total production amount.Therefore,the carbonization of harden cement paste is delayed from the chemical level.Polymer coating can inhibit the surface micro-crack of harden cement paste.In addition,the total porosity and amount of capillary（100 nm） of harden cement paste may reduce after coating with polymer,thus the carbon dioxide-permeation resistance of harden cement paste is improved and the carbonization resistance is enhanced.