Characteristics of autoclaved lightweight aggregates with quartz tailings and its effect on the mechanical properties of concrete

Herein, we prepared autoclaved lightweight aggregates containing quartz tailings (QT) and determined their effect upon mechanical properties of concrete. QT, by pelletizing and autoclaving, were directly mixed with quicklime, cement and fine river sand to prepare lightweight aggregates, denoted as autoclaved QT aggregate (QTA). The prepared QTA were then used as coarse aggregates in manufacturing concrete. QT were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size distribution analyzer; whislt the CaO/SiO2 ratio of QTA was investigated. The compressive strength and the structure efficiency of concrete containing the preapred QTA were thereafter determined. Results exhibit that QTA with the CaO/SiO2 ratio of 0.4 has the highest cylinder compressive strength of 20.6 MPa. The 28-d compressive strength of the QTA concrete is 74 MPa, retaining 95% of that of crushed stone (CS) concrete. The oven dry density of QTA concrete however dips 19% relative to the counterpart (CS concrete). It results in a 37.88 MPa.m(3)/t structure efficiency of QTA concrete, or 24% higher than the counterpart. The research is expected to provide an effective appraoch to reduce solid wastes paricularly QT. (C) 2020 Elsevier Ltd. All rights reserved.