Evaluation of the fracture behaviour of a fibre reinforced earthen material using digital image correlation

Earthen materials have recently earned renewed consideration and interest in the construction industry because of their abundance, low cost, and technologically simple and energy-efficient production processes, which make these materials suitable for use in developing countries and in rural, protected and architectural heritage sites. In addition to the many positive economic and environmental factors, unfired earth provides excellent sound and thermal insulation, combined with good fire resistance and humidity control properties. There are however a few significant limitations, which have restrained a wider use of earth-based materials in the building and construction sector. The low strength and the brittle behaviour are certainly the major issues for a structural use of this class of materials. For this reason, vegetal and animal fibres have been often used to improve the mechanical properties of the base soil material. However, relatively few studies have been conducted to characterize the efficiency of fibrous reinforcement for the enhancement of the fracture resistance and the energy dissipation capacity of earthen materials. In this study, notched samples made of soil and reinforced by hemp fibres with different percentages and lengths were manufactured and statically tested in bending. Digital Image Correlation (DIC) analyses were carried out to investigate the influence of the fibres in controlling the fracture resistance of the material.