Moisture ingress in rammed earth: Part 3 – Sorptivity, surface receptiveness and surface inflow velocity

Abstract

Calculations and data for the sorptivity ( S), surface receptiveness ( o) and surface inflow velocity ( u o ) in different rammed earth mix recipes have been presented and compared with those of conventional masonry materials. The sorptivity of rammed earth is generally very low and compares favourably with conventional masonry materials. Capillary moisture ingress in rammed earth appears to obey the extended Darcy equation. The surface inflow velocity ( u o ) appears to decrease linearly against t 0.01. The gradient of u o / t 0.01 provides the surface receptiveness ( o) which quantifies the surface finish of the material and is positively related to the effective hydraulic pore radius ( r) of the soil. A rammed earth mix recipe appears to be optimised for low sorptivity and high dissipation where the 3.35 ratio, defined in this series of papers, is five or less.