Fibre reinforcement in earthen construction materials

Earthen construction materials are generally brittle with low tensile strength. To deal with this in practice, it is often proposed that reinforcement be added in the form of fibres of various materials. Construction in earthquake-prone parts of the world is thought to benefit from this form of reinforcement, and indeed fibres (in the form of straw) are a key part of many adobe (unit-based) materials. To remain in harmony with the generally excellent environmental credentials of these materials, the reinforcement should be obtained from a natural material ideally obtained as a waste stream, so natural fibres are often chosen. While some studies have been published on the macroscopic mechanical behaviour of reinforced earthen materials, little is known of what is happening at the interface between the soil matrix and the fibres. In this paper, the authors present laboratory-based studies that attempt to fill this gap, covering pull-out behaviour of natural fibres embedded in earthen construction materials, both stabilised and unstabilised.