Effects of applied load and its direction on the permeability behavior of concrete: A case study

The applied load has significantly impacted on the permeability behavior of concrete. Although many investigations have reported the impact of loading level on the permeability, the influence of loading direction on the permeability received little consideration in previous publications. Therefore, this work gives a comprehensive study on the influence of loading level and its direction on water and chloride permeability. Applied loading experiment, water absorption experiment and chloride diffusion test were conducted in this work. The findings showed that the applied load increased the specific crack area and pore size distribution, and that the permeability increased as the applied loading level and duration increased. The water and chloride penetration whose direction is vertical to the applied loading direction is greater than that whose direction parallels the loading direction; in addition, the applied load direction shows larger effects on water ingress than on chloride ingress. Capillary absorption coefficient and chloride diffusion coefficient grow linearly as total porosity increases, and the chloride diffusion coefficient is in direct proportion to the capillary absorption coefficient. When the loading direction is vertical to water penetration, the capillary absorption coefficient of concrete after 75 % fc and 85 %fc increases by 25.76 and 28.27 (g/m2h1/2), compared with the case that the loading direction is parallel with water penetration. This paper further gives a relationship between concrete permeability and the induced loading damage.