Review of lightweight cellular concrete: Towards low-carbon, high-performance and sustainable development

With the continuous intensification of global climate issues, the innovation and replacement of wall materials as an important component of the construction industry is imperative. Lightweight cellular concrete (LCC) emerges as an energy-saving and low-carbon building material due to its well thermal insulation properties and lower cement usage. Traditional LCC includes autoclaved cellular concrete (ACC) and moisture-cured cellular concrete (MCC). The former involves substantial energy consumption in its high-temperature (120–200 °C) and high-pressure (5–18 bar) curing (generally 6–12 hours), while the latter faces challenges of prolonged curing periods (generally 3–28 days) and limited mechanical performance (0.5–2 MPa). Recently, carbonated cellular concrete (CCC) has gained prominence in research due to its rapid development of mechanical properties (2 hours to 3.5–8 MPa) and high CO2 sequestration (120–150 kg/m3). Even some solid wastes, such as magnesium slag and steel slag, can be used as the primary or sole binders in the preparation of CCC, positioning it as a focal point in the field of sustainable construction practices. However, CCC also suffers from limited degree of reaction (35–70 %) and relatively low homogeneity, which is the main direction for CCC to be improved in the future. The purpose of this review is twofold: (1) to systematically compare the macro/microscopic structure and performance of CCC with those of conventional ACC and MCC, filling in the gaps in this part of the understanding, so as to more accurately understand the strengths and weaknesses of the three; (2) to allow readers to more accurately control the direction of the development of LCC and the requirements of the innovation, in order to be more adapted to the global low-carbon and sustainable development policy. Achievement of the objectives is based on an in-depth review of those three types of LCC, focusing on their composition and physical properties (such as void structure, mechanical performance, sorption characteristics, thermal insulation capabilities and carbon footprint). Additionally, an analysis and outlook were also conducted on the market trends of three types of LCC.