Effect of nanoparticles on foaming agent and the foamed concrete

Nanoparticles are expected to improve properties of foaming agents and that prefabricated foams, further the performances of foamed concrete. In this study, foaming agents were prepared by introducing a certain content of nano-SiO2 (NS) and graphene (G), respectively. Effect of nanoparticles on foaming agent and that prefabricated foams has been investigated. Stability of prefabricated foams could be improved with the addition of NS, which might be attributed to the increased viscosity and a few changes in surface tension of foaming agents with NS. However, stability of the prefabricated foams would be degraded with the addition of G due to the obvious increase in surface tension of foaming agent with G. Furthermore, prefabricated foams through foaming agents with nanoparticles were used to prepare foamed concrete at dry density level of 500 kg/m(3). Foamed concretes with decreased and evenly distributed pore sizes were obtained when foaming agents with NS were used, which is related to the much higher stability of prefabricated foams. Proper content of nanoparticles in foaming agents and the prefabricated foams can improve the mechanical properties of as-prepared foamed concrete. However, improvements for other performance of foamed concrete, such as thermal conductivity, water absorption and shrinkage, were not obvious when foaming agent with nanoparticles were used. (C) 2019 Elsevier Ltd. All rights reserved.