Novel high-efficiency solid particle foam stabilizer: Effects of modified fly ash on foam properties and foam concrete

The preparation of foam concrete frequently encounters challenges such as foam collapse and stratification, which lead to a decline in material performance. Therefore, enhancing foam stability is paramount in the production of foam concrete. This study innovatively addresses this issue by investigating the use of waste fly ash particles (RFA) and modified fly ash (AMFA, BMFA, and CMFA) as foam stabilizers, and comparing their efficacy with that of traditional nano-silica stabilizers (NS), both independently and in combination. The results indicate that modified ultrafine fly ash particles (AMFA) exhibit foam stability properties (1-h settlement distance and bleeding rate) comparable to those of NS. Moreover, when combined with NS, the mixture surpasses the foam performance of NS alone. Utilizing these highly stable foams, lightweight foam concrete with a 600 kg/m³ density is produced, demonstrating exceptional mechanical properties (compressive strength of 3.42 MPa) and superior thermal insulation (thermal conductivity of 0.0914 W/m· K). The enhanced foam stability of the modified fly ash is primarily attributed to increased surface roughness, hydrogen bonding, and van der Waals forces. Developing highly stable foams holds significant potential, contributing to energy conservation, emissions reduction, and waste management.