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Synergistic use of industrial solid waste mixtures to prepare ready-to-use lightweight porous concrete

Yao, Xingliang, Wang, Wenlong, Liu, Min, Yao, Yonggang, Wu, Shuang
Journal of cleaner production 2019 v.211 pp. 1034-1043
aluminum, compression strength, concrete, construction materials, dust, energy, energy conservation, environmental impact, flue gas desulfurization, fly ash, gypsum, life cycle assessment, natural resources, pastes, raw materials, slags, solid wastes, thermal conductivity
Lightweight porous concrete is a popular energy-saving building material. However, the raw materials required to prepare this concrete paste are extracted from natural resources, and its early compressive strength is so low that it cannot be used for applications with a short casting time. In order to improve the early compressive strength and reduce energy and resource consumption during preparation, this study proposes using only solid wastes to prepare the pastes for lightweight porous concrete that can be ready to use in a short time. This was achieved by sintering a mixture of aluminum dust, flue-gas desulfurization gypsum, carbide slag, and red mud to obtain a cementitious material (CM). Then, other solid wastes (14.26 wt% flue-gas desulfurization gypsum, 9.9 wt% fly ash, and 1 wt% carbide slag) were blended with the CM to prepare ready-to-use lightweight porous concrete (RLPC), which was successfully prepared using only industrial solid wastes as the raw materials. The minimum thermal conductivity obtained was 0.15 W/m·K, and the maximum 28-d compressive strength obtained was 3.57 MPa for an RLPC dry density of ∼600 kg/m3. In addition, the 4-h and 1-d compressive strengths were up to 1.31 MPa and 1.57 MPa, respectively, which is even higher than the 28-d compressive strength of most conventional foamed concretes. Finally, our life cycle assessment showed that the preparation of RLPC has a lower environmental impact than that of conventional foamed concrete.