Stress-strain behaviour and acoustic emission characteristic of gangue concrete under axial compression in frost environment

Coal gangue concrete can effectively utilise coal gangue, minimise natural stone and has substantial environmental and economic benefits. At high-latitude and high-altitude regions, the durability and bearing capacity of gangue concrete structures are critically threatened by freeze-thaw cycles. Here, the freeze thaw cycles experiment was performed using the accelerated freeze-thaw method. Various characteristic parameters, such as stress-strain curve and acoustic emission under axial compression, were measured for the frost-damaged coal gangue concrete. The volume replacement rates of coarse aggregate mixtures (C1, C1M2, C1M4 and C1M6) were 0%, 20%, 40% and 60%, respectively. After freeze-thaw cycles, water absorption and square root of time were nonlinearly related, showing a relatively rapid growth in the early stage, a gradual increase in the middle stage and stability and balance in the late stage. Water absorption rate was positively correlated with the gangue content in concrete. The physical and mechanical properties of gangue concrete decreased with prolonged freeze-thaw cycles, and the degradation rate increased with the gangue amount. The damaged layer thickness and peak strain increased, whereas the initial elastic modulus, peak stress and toughness decreased. The parameter alterations increased with the gangue content in concrete. The damage evolution rule of gangue concrete under axial compression was accurately described by acoustic emission. (C) 2019 Elsevier Ltd. All rights reserved.