MODELING THE INFLUENCE OF STRESS LEVEL ON CHLORIDE TRANSPORT IN PRESTRESSED CONCRETE

The concrete under the state of tension or compression stress can influence the micro-structure of inner composite materials, and consequently change some properties of concrete, such as porosity and permeability. Therefore, the chloride transport in saturated concrete will also be influenced by the stress level of concrete because the transport process depends on the porosity of concrete. In this study, three series of stressed concrete specimens with W/C=0.40 and 0.50, Series A, Series B and Series C (compression stress, tension stress and none stress states, respectively), were subjected to accelerated salt fog aggressive experiment. The test results indicate that the chloride content at certain depth decreases with increasing compressive stress levels while increases with increasing tensile stress levels, especially for high W/C specimens. Then, the surface chloride diffusion coefficient, D-surf, is calculated with error function solution when the diffusion is considered as the main mechanism of chloride transport. And several factors influencing the chloride diffusion coefficient in concrete are analyzed and the influential coefficient of concrete stress level is proposed particularly in this study. By comparing the calculated D-surf, an approximately linear relationship between diffusion coefficient and stress level is obtained.