A novel integration strategy for the foaming and hydrophobization of geopolymer foams. (October 2022)

• Record Type: Journal Article
• Authors: Dong, Chunling; Shao, Ningning; Yan, Feng; Ji, Ru; Wei, Xuankun; Zhang, Zuotai
• Is Part Of: Cement and concrete research. Volume 160(2022)
• Publication Date: 2022-10
• Subjects: Fly ash -- Geopolymer foams -- Polymethylhydrosiloxane -- Foam control -- Hydrophobization; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2022.106919
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: Traditionally, hydrophobic geopolymer foams (GPFs) are prepared in two steps: GPFs hardening and hydrophobic treatment. Here, we reported a novel two-in-one strategy for the simultaneous foaming and hydrophobization of GPFs by using polymethylhydrosiloxane (PMHS) as the key double-functional agent and calcium stearate (CS) as the foam stabilizer. With the combined effect of PMHS and CS, the pore size could be controlled in the range of 0.27–6.82 mm and bulk density in 200–700 kg/m 3, which further influenced the compressive strength and thermal conductivity. The as-prepared GPFs showed superhydrophobic properties, with contact angles as high as 170°. Theoretically, alkylated nano‑silicon fibers grew on the GPFs surface, which acted as a hydrophobic cover and increase the surface roughness, both contributing to the superhydrophobic. Overall, our work presents a novel two-in-one strategy for the preparation of superhydrophobic GPFs, which would be of great significance to the application of GPFs. Graphical abstract: Unlabelled Image Highlights: A novel two-in-one strategy was proposed for preparation of hydrophobic GPFs. The contact angel was as high as 170°. PMHS could release H2 and simultaneously form alkylated nano‑silicon fibers.