Study of the effect of flax fibers on the fracture behavior of earth concrete by simultaneous application of digital image correlation and acoustic emission

Abstract

Nowadays, construction using natural materials such as earth-based concrete is of major interest for a sustainable society and in response to the challenges of global warming. These materials allow a significant reduction of CO2 and energy consumption in the production process. However, the presence of fine particles in earth concrete makes it sensitive to plastic shrinkage and consequently to cracking risk. Thus, flax fibers have been added to earth concrete to enhance its properties and to prevent the appearance of shrinkage cracking. The effect of adding flax fibers in different percentages (0%, 0.3% and 0.6%) and lengths (12 mm, 24 mm, 50 mm) on fracture properties of earth concrete has been studied. Compressive tests have been conducted on cubic specimens of 10x10x10 cm 3 at 7, 28 and 180 days. Flexural tests have been also realized on prismatic specimens at 28 days. Those tests have been monitored simultaneously with the digital image correlation (DIC) and the acoustic emission (AE) techniques. The results show that the compressive strength, the tensile strength and the AE activity increased with the addition of fibers. Crack displacement fields of hardened concrete and the AE events showed also the development of multi-cracking with the addition of fibers. Those later enhanced the ductility of earth concrete due to fibers bridging of the cracks.