Preparation and properties of foamed cement for lightweight thermal insulation with Ti-extraction blast furnace slag and sulfoaluminate cement by chemical foaming

Ti-extraction blast furnace slag (TEBFS) is a chlorine-containing solid waste produced by the metallurgical industry in China. The accumulation of TEBFS is harmful to the environment and the sustainable development of industry. Herein, foamed cement was prepared as a load-bearing and insulation material using TEBFS and sulfoaluminate cement (SAC) by chemical foaming. The effects of TEBFS content, H2O2 content, and calcium stearate content on the properties, pore structure, and microstructure of the samples were explored. The results show that a stable foam system was obtained by mixing 20–40% TEBFS with SAC, and the most influential factor on the material properties of the samples was H2O2 content. The relationship between the average pore size and bulk density was y = 0.6219x − 0.7194 (R2 = 0.99). Based on an orthogonal experiment, the most influential factors for determining the bulk density, compressive strength, and thermal conductivity of the samples were the H2O2 content and the TEBFS content. The optimal foamed cement was produced with 40% TEBFS, 1% H2O2, and 1.0% calcium stearate. The water-cement ratio was 0.5. The bulk density, 28-day compressive strength, and thermal conductivity of this sample were 0.68 g/cm3, 1.86 MPa, and 0.17 W/(m·K), respectively. Morphological analysis demonstrated that the complete pore structure was helpful for improving the compressive strength of the foamed cement material. XRD showed that the main phases generated in this sample were ettringite, calcium silicate hydrate (C-S-H), and Friedel salt. © 2022 Elsevier Ltd