Study on the performance of calcined spent waterglass foundry sand in alkali-activated foam concrete

The resource utilization of spent foundry sand (SFS) helps solve environmental problems and reduce construction costs. Using SFS as fine aggregate incorporated into concrete for practical application has recently become a research hotspot. However, researchers are rarely concerned about the application of SFS in alkali-activated foamed concrete (AAFC). AAFC is a lightweight concrete material with excellent thermal insulation and fire resistance while reducing CO2 emissions. In this paper, spent foundry waterglass sand (SwFS) calcined at 900 degrees C replaced fine aggregates (0%, 20%, 40%, 60%, 80%, 100%) to prepare AAFC. This paper studied the performance of calcined SwFS in alkali-activated foam concrete. The experimental results show that the SwFS suffered calcined at 900 degrees C release SiO32- at slow speeds in AAFC and can be an auxiliary activator for AAFC. In addition, the compressive strength of AAFC with SwFS added to 900 degrees C increased by 15% - 29% and 15% - 25% at 3 d and 7 d, respectively, and decreased slightly at 28 d.