Preparation of Ultralight Foam Concrete by the Synergistic Modification of a Foaming Agent with Hydroxypropyl Methylcellulose and Silica Fume

In order to overcome the difficulties of poor foam film stability and easy collapse of bubble structure in the preparation of ultralight foam concrete, a new strategy of using hydroxypropyl methylcellulose (HPMC) and silica fume (SF) to synergistically modified animal protein foaming agent was proposed. Through systematic research on the macroscopic properties and microstructure of the modification system, the results showed that in the case of 0.4% HPMC and 5% SF compounding, the comprehensive performance of the foam could be significantly improved, and ultralight sulfoaluminate cement-based foamed concrete (U-SCFM) with a dry density as low as 45 kg/m3 was successfully prepared. Mechanistic studies have shown that SF stabilizes animal protein foam through dual routes: the silanol groups on the surface of SF not only interact with the sodium dodecyl sulfate (SDS) in the protein foaming agent, but also generate electrostatic attraction with the amino acids produced by the hydrolysis of the protein foaming agent through Coulomb forces, causing SF adsorb onto the surface of the bubble film. With the help of the aforementioned routes to strengthen the liquid film of bubble and optimize the pore structure of bubble, the gas-liquid two-phase foam is decorated into a solid-liquid-gas three-phase foam, which improves the strength and stability of the foam.