Universal soil shrinkage curve equation

•The shrinkage curve consists of two to four phases.•The shrinkage curve is modelled as a series of linear and curvilinear segments.•It is difficult to describe all shrinkage curves with a single continuous equation.•A universal equation is proposed to describe all types of shrinkage curves.•The proposed equation performed better than extant equations.

The soil shrinkage curve is used to relate the volume of soil as it dries with water content. The shape of shrinkage curve depends on the soil type and soil fabric. A shrinkage curve can consists of two to four phases. It is difficult to represent all types of shrinkage curves with a single continuous equation which uses explicit parameters. In this paper, a universal shrinkage curve equation with explicit parameters is proposed which can be used for all types of shrinkage curves. Application of the proposed equation is illustrated with published data. Comparison of the proposed equation with other shrinkage curve equations is made in terms of goodness-of-fit measures with experimental data.