Sol–gel-stabilized CO2 foam for enhanced in-situ carbonation in foamed fly ash backfill materials

Abstract

A novel highly stable aqueous foam was synthesized using CO2, sodium silicate (SS) and anionic surfactant of sodium dodecylbenzene sulfonate. The influence of CO2 foam on the mechanical properties and its underlying mechanisms of foamed backfill material was investigated. The experimental results revealed that the addition of CO2 and SS effectively reduced the drainage of the foam while strengthening the liquid film of the Plateau borders, which stabilizes the foam. The excellent stability is attributable to the gel network developed after SS exposed to CO2, that adhere to the foam surface. Furthermore, due to the interaction between encapsulated CO2 and hydration products, micro CaCO3 formed and filled the pore wall; thus, precast foam forms robust pore structures in the hardened foamed backfill.