Effect of foaming agent on physical and mechanical properties of alkali-activated slag foamed concrete

Alkali-activated slag cement has the characteristics of high viscosity, quick hydration, setting and hardening, and high strength, which are suitable for the preparation of foamed concrete. Three foaming agents of sodium alpha-olefin sulfonate (AOS), sodium dodecyl sulfate (K12) and sodium alcohol ether sulphate (AES) with the same foam stabilizer of silicone resin polyether emulsion FM-500 (MPS) were used to prepare foam. The three foam properties are similar and foam stability of AOS and K12 is better than that of AES. Effective foam ratio is put forward to express stability of foam in paste slurry. Effective foam ratio and porosity has a great effect on dry apparent density of water glass-activated slag foamed concrete. With the increase of foam content, effective foam ratio of AES decreases obviously, while that of K12 and AOS show a slight decrease. At low foam content, AES can better reduce the dry apparent density. Increase foam content of AOS and K12 appropriately may reduce dry apparent density. R-sd and compressive strength of foamed concrete with AOS foam is the highest. When porosity is similar, average pore size and pore size distribution has a great effect on thermal conductivity and mechanical properties of AAS foamed concrete. Average pore size of O3 is smaller than that of K3 and E3. O3 also shows the narrowest air-void size distribution with the majority of the voids smaller than 400 mu m. Average roundness of three type foam is much the same. Foam stability is the main factor affecting pore structure of AAS foamed concrete. AOS can be preferred to prepare AAS foamed concrete. (C) 2019 Elsevier Ltd. All rights reserved.