Water movement in porous building materials—IV. The initial surface absorption and the sorptivity

Abstract

The Initial Surface Absorption (ISA) test is discussed in relation to the theory of water absorption by porous materials. Water absorption from finite sources is analysed in terms of the sharp wet front model. It is shown that the wetted region produced by a line source is a semi-ellipse and that by a circular source is an oblate hemispheroid. Generally the rate of absorption is not proportional to t −1 2 . Experimental data on brick are included.