Evolution of acoustic emission activity throughout fine recycled aggregate earth concrete under compressive tests

•The effect of recycled sand and clay content on the mechanical and fracture properties of earth concrete has been studied.•The damage has been monitored throughout the entire compressive tests by means of acoustic emission technique and digital image correlation.•A warning sign of potential failure of earth concrete is proposed. Pourable earth concrete is a new form of earth construction that may be, for different applications, an alternative to cement concrete. The ecological benefits of such mixture will be more important if it was formed with fine recycled aggregate. However, earth construction materials are of low strength and thus the assessment of their mechanical properties is of high importance. In this paper, the mechanical behavior of natural sand (NS) and recycled sand (RS) earth concrete mixtures of different clay amounts has been assessed. Uniaxial compressive tests were carried out at different curing ages and were monitored in parallel with acoustic emission (AE) and digital image correlation (DIC) techniques. Different mechanical properties have been examined at the age of 14, 28 and 90 days. The results revealed a decrease in the mechanical properties and fracture energy from one side and increase in the fracture toughness from other side when RS replaces NS and with clay content. Furthermore, according to the AE activity evolution throughout the compressive tests, different phases during the fracture process of earth concrete were distinguished: compaction phase, linear phase, stable crack growth phase, unstable crack growth phase and softening phase. AE reflected differently each phase and by means of AE activity and energy, it has been alleged that RS mixtures are of lower ITZ properties.