THE ABSORPTION OF WATER INTO A POROUS SOLID CONSISTING OF 2 DISSIMILAR LAYERS

Analytical modelling of the movement of water through porous solids co nsisting of more than one homogeneous layer is a problem in soil scien ce and in construction engineering. In this paper equations based on t he Green and Ampt model describe the absorption of water into a two-la yer composite bar for the cases of absorption through a material of la rge sorptivity into one of smaller sorptivity and vice versa. These pr edictions are compared with experimental results. There is broad agree ment between theory and experiment at all times. We conclude that the absorption of water into a two-layer composite is ultimately controlle d by the second material in the absorbing sequence irrespective of whe ther this material has the larger or the smaller sorptivity.