Mechanical properties of molybdenum tailings concrete after exposure to high temperature

Abstract

In this paper, 75 concrete prisms were tested under different temperatures (20, 200, 400, 600 and 800 °C) and molybdenum tailings replacement ratio (0, 25, 50, 75, and 100 %). The axial compression failure modes and mechanical properties of molybdenum tailings concrete were studied. The results show that the increase in temperature will aggravate the failure of concrete under axial compression, instead of molybdenum tailing replacement ratio. With the increase of temperature (20–800 °C), the surface color of the concrete becomes lighter, and obvious cracks began to appear from 400 °C, the mass loss ratio and peak strain of molybdenum tailings concrete show an increasing trend, and reach the maximum growth ratio (6.58 % and 34 %) at 800 °C. The peak stress and elastic modulus of molybdenum tailings concrete show a decreasing trend, and reach the maximum reduction at 800 °C (52 % and 71 %). With the increase of replacement ratio, the mass loss ratio of molybdenum tailings concrete increases linearly. The peak stress, peak strain and elastic modulus of molybdenum tailings concrete at all temperatures increase first and then decrease. The 25 % molybdenum tailings content can improve the deterioration of molybdenum tailings concrete after exposure to high temperature. Based on the experimental data, the prediction formulas of peak stress/strain and elastic modulus of molybdenum tailings under different temperature-molybdenum tailings replacement ratio coupling conditions are fitted respectively. The experimental and calculated values of the formula are in good agreement.