混凝土碳化区和非碳化区微观结构的研究

Study on the Microstructure of Carbonization Zone and Non-carbonized Zone of Concrete

空气中CO_2气体渗透到钢筋混凝土内,降低混凝土碱度,导致钢筋锈蚀和混凝土劣化。为阐明碳化过程中,混凝土表层的碳化规律及碳化区域微观结构的劣化过程,本研究采用加速碳化的方法,研究了混凝土随龄期的碳化规律、碳化区域以及未碳化区域的组成和微观结构分析。研究结果表明,大气环境中的CO_2通过混凝土表面结构的孔隙逐渐侵入到混凝土内部结构中,使混凝土表层结构发生变化,导致混凝土表面更加致密。混凝土碳化过程中,碳化区域形成大量碳酸钙,且随着碳化龄期的延长其含量增加。同时碳化区域的碱度降低,孔溶液pH值降低,且随着碳化龄期的延长进一步降低。

The alkalinity of reinforced concrete decreases due to the infiltration of CO2, which causes the corrosion of steel bars and concrete deterioration. In order to illustrate the carbonization process and the microstructure degradation process of carbonization zone, the experiments of accelerated concrete carbonization are conducted. The results indicate that the microstructure of carbonization zone is changed, namely, the density of its surface increases.The amount of CaCO3 is generated and the content of CaCO3 grows with the increase of carbonization age. Meanwhile,the pH value of pore solution of the carbonization zone decreases with the increase of carbonization age.