Suitability of Different Stabilizing Agents in Alkali-Activated Fly-Ash Based Foams

Alkali-activated foams (AAFs) are inorganic materials produced from aluminosilicate sources, such as fly-ash and metallurgical slag or clay, which contain air voids in their matrices. One possible route to the pore-forming process is chemical foaming through the use of a blowing agent such as hydrogen peroxide. Gaseous products (e.g. O₂) are formed during this process and then become trapped in a solidified structure during the hardening stage. In order to avoid the collapse of pores during this process various stabilizing agents (surfactants), such as sodium oleate, sodium dodecyl sulfate (both anionic surfactants), and Triton X 100 (nonionic surfactant), are also added to the mixture. In the present study, the AAFs were formed using fly-ash from a Slovenian thermal plant and H₂O₂ as a foaming agent. The air voids were stabilized through the addition of three different surfactants: sodium oleate, sodium dodecyl sulfate, and Triton. The effects of different quantities of foaming and stabilizing agents and different types of stabilizing agents on the mechanical properties and microstructure of foams were investigated.