Evaluation of the equation of water penetration into concrete using results of "Cylindrical chamber" method

Permeability is one of the most effective parameters on concrete durability. Therefore, in this paper penetration of water into concrete is studied. Although most of the researchers have considered the coefficient of permeability obtained from one dimensional Darcy’s equation, in the present paper due to movement of water in all directions, two-dimensional diffusion equation which defines penetration of fluid into a porous material has been used for first time. For this purpose, cubic concrete specimens with different W/C ratios were prepared and their permeability was measured using “Cylindrical chamber” method. In this method, applied pressures and durations of water penetration were varied. The two-dimensional equation considered, was solved using Laplace and Henkel transformations and the obtained results were compared with the “Cylindrical chamber” results. Comparison of the theoretical and experimental results showed that the average respective percentage errors calculated for the estimation of wet curve, maximum penetration depth, average penetration depth and wet surface were 23.07, 13.64, 21.41 and 1.66. The coefficients of determination between pressure magnititude and duration of water penetration, considering the variables of maximum penetration depth, average penetration depth, wet surface, penetrated volume and optimum diffusion coefficients were seen to be higher than 0.95. Furthermore, no reliable correlation was observed between the optimum diffusion coefficients and the mentioned variables.