Preparation and properties of ready-to-use low-density foamed concrete derived from industrial solid wastes

Abstract

Foamed concrete is widely used as a highly energy-efficient building material. However, low-density foamed concrete requires increased amounts of Portland cement or steam curing to meet engineering requirements. This is due to inadequate compressive strength and long setting time of Portland cement. In this study, we investigate a method for preparing green, high strength, low-density foamed concrete, which is ready to use without the application of heat or pressure. First, a sulfoaluminate high-activity material (SHAM) was prepared using red mud, aluminum dust, flue gas desulfurization-gypsum, and carbide slag. The SHAM was used to produce ready-to-use low-density foamed concrete (RLFC). RLFC with a dry density of 615 kg/m3 had a compressive strength of 4.11 MPa and a thermal conductivity of 0.1638 W/m·K. Addition of 0.2 wt% hydroxypropyl methylcellulose (HPMC) as foam stabilizer, increased the compressive strength by 27.22% to 5.22 MPa, which was 3.48 times the compressive strength specified by the relevant Chinese standard (1.5 MPa). To further enhance the practicality, other solid wastes (limestone tailings and gold tailings) were blended with SHAM to prepare the RLFC. RLFC prepared from SHAM, limestone tailings, gold tailings, and HPMC in the match ratio of 54:6:40:0.11 (wt%) delivered dry density, compressive strength and thermal conductivity values of 612 kg/m3, 2.37 MPa and 0.1556 W/m·K, respectively. This study provides a low-cost and highly promising method for preparing low-density foamed concrete, which not only consumes a large amount of industrial solid waste but also avoids depletion of resources and generates profits.