According to C Hall and W D Hoff, the sorptivity expresses the tendency of a material to absorb and transmit water and other liquids by capillarity.
The sorptivity is widely used in characterizing soils and porous construction materials such as brick, stone and concrete.
Calculation of the true sorptivity required numerical iterative procedures dependent on soil water content and diffusivity. John Philip (1969) showed that sorptivity can be determined from horizontal infiltration where water flow is mostly controlled by capillary absorption:
where S is sorptivity, I is the cumulative infiltration at time, t.
For vertical infiltration, Philip's solution is adapted using a parameter A1. This results in the following equations, which are valid for short times: cumulative: , rate where the sorptivity S is defined (when a sharp wetting front Lf exists, as:
- Philip, John R (1957). "The theory of infiltration: 4. Sorptivity and algebraic infiltration equations". Soil Science 84: 257–264.
- Hall, Christopher; Hoff, William D (2012). Water transport in brick, stone and concrete, 2nd edn. London and New York: Taylor and Francis.