Fracture Energy of Stabilised Rammed Earth

Abstract

Unstabilised rammed earth (RE) is the name given to both a construction method and a material that has been used by Man for thousands of years. Recently, it has received renewed interest as the desire for sustainable construction methods has increased, as it commonly uses subsoil from the construction site, hence reducing waste and transport costs. It has been established that the addition of stabilisers, such as cement or lime, increases the ultimate compressive strength (UCS) of RE, while the addition of fibrous material, such as straw or wool, has been shown to improve flexural strength. This paper describes experimental work investigating the fracture properties of RE, an area in which little research has been conducted to date, despite the brittleness of most variants of these materials. The effect of both stabilisation and fibre reinforcement are reported here from samples with 0-12% by mass of cement and different amounts (0%, 1%, 2% by mass) of waste fibres. Fracture energies were determined using a modified wedge splitting test (WST) and results are presented that demonstrate the clear effect of fibrous reinforcement on specific fracture energy.