Foamed concrete produced from CO2/N2 foam stabilized by CaCO3 nanoparticles and CTAB

Abstract

Foamed concrete (FC) has garnered popularity, especially with the growing demand for energy-efficient and sustainable construction materials. The stability of the FC slurry as it sets is crucial to the uniformity of the pore structure and, subsequently, FC performance. This study investigates the stability of a novel FC produced using aqueous CaCO3 nanoparticle (NP)/hexadecyltrimethylammonium bromide (CTAB) foam. The effect of NPs and gas type (pure N2, pure CO2, and a 2:1 gas mixture of CO2/N2) on the FC dry density, compressive strength, water absorption, macro- and microstructure, hydration products, and thermal insulation is explored. The results show that the dry density of FC increases with the inclusion of CO2 owing to gas liberation during mixing with the paste leading to less voids. Using the gas mixture, CaCO3/CTAB foam increases the compressive strength of the FC by 38% compared with CTAB alone owing to enhanced uniformity of the pore structure and a denser hydrated paste skeleton. Such structure leads to less connected pores, which reduces atmospheric carbonation, and improves thermal insulation performance. A 2-fold decrease in the largest pore size and a 25% decrease in surface temperature when exposed to an open flame are also achieved in the presence of CaCO3 NPs.