Effect of hydroxypropyl methylcellulose as foam stabilizers on the stability of foam and properties of foamed concrete

Abstract

The stability of precast foam was a key factor in the performance of situ casted foam concrete (FC). Enhancing the viscosity of the foaming liquid is considered to be an effective way to improve the stability of precast foams. hydroxypropyl methylcellulose (HPMC) has become a widely used thickener in cement and concrete. In this study, HPMC was used to enhance the basic properties of foamed concrete (FC). The properties of foam and FC were tested using different test methods. The findings indicated that HPMC could improve the stability of foam by adsorbing on the surface of gas-liquid film; the mechanism of this stabilization process was explained as follows: the gas-liquid interfacial tension of foam was reduced, thus enhancing the strength and toughness of liquid film; HPMC enhanced the viscosity of the foaming solutions, thus affecting the drainage rate of foam and the diffusion rate of inter-bubble gas. HPMC could also effectively optimize the bubble size and uniformity of the bubble size distribution, delaying the foam disproportionation and coalescence. Furthermore, HPMC refined and homogenized the pore structure of FC, contributing to the enhancement of its strength.