Influence Of Two Factors On Concrete Permeability: Chloride-Ion Resistant Agent And Polymer Impregnation After Exposure To High Temperature

This thesis presents an experimental study on the influences of a chloride-ion resistant agent (Cl~--Agent) and polymer impregnation on permeability of concrete. Electric charge passed through concretes was measured according to CECS 207 and chloride ion contents in a series of mortar were tested. Permeability and mechanical properties of concrete exposed to elevated temperature and polymer impregnation were determined, and compared with those of control concretes.The experimental results reveal that the Cl~--Agent can absorb chloride ions rather than improve the permeability of concrete. When the Cl~- -Agent was added at a dosage of 6% into concrete and mortar, the resistance to penetration of chloride ions could be improved greatly, for which the mechanism is chloride ions absorption by the Cl~--Agent. Nevertheless, the influence of Cl~--Agent on mechanical properties and internal structure of concrete was insignificant, but, when a combination of the Cl~-Agent and fly ash or slag was added into concrete, the resistance to penetration of chloride ions could be improved more greatly than Cl~--Agent, fly ash or slag added lonely.Polymer impregnation can effectively increase residual mechanical properties and permeability of concrete exposed to high temperature. After exposure to high temperature, polymer impregnated could fill pores and cracks, which were produced or growed to a greater sizes due to exposure to high temperature, and hence make the system more compact, so as to improve the permeability and other property too. Mechanical properties of concrete exposed to elevated temperature and polymer impregnation can be improved to some degree, and even in some cases these properties can be better than those of control concrete without exposure to high temperature.All the results indicate that both the Cl~--Agent and polymer impregnation improved resistance to penetration of chloride ions. But the mechanism of the Cl~--Agent is absorption of chloride ions which penetrated into concrete and mortar, and it has little influence on internal sturcture of concrete. Polymer filled pores and cracks in concrete, made concrete more compact, then greatly decreased penetration of water and other deteriorative ions. Polymer impregnation not only improved resistance to penetration of concrete, but also increased mechanical properties of concrete.