Thermal insulation and setting property of inorganic solidified foam

Abstract

Thermal insulation and setting properties are considered to be two significant parameters when inorganic solidified foam (ISF) is applied to control and extinguish coal fires. Based on studies concerning the thermal properties of porous media and experimental research on the relationship between porosity and the addition of aqueous foam, an equation describing the change in thermal conductivity with aqueous foam volume is deduced and then amended. Microscopic analysis of the process of setting is conducted by scanning electron microscopy. The results show that the coagulation of a single bubble wall and bubbles connecting with each other lead the ISF to lose fluidity gradually. A loss of fluidity time (LFT) index is then proposed on the basis of field process requirements and the aforementioned microscopic analysis, and a home-made instrument to test LFT is developed. Effects of aqueous foam volume and accelerator type, along with its addition quantity, on the LFT of ISF are investigated. The relationship equation provides a theoretical foundation for steerable adjustment of the LFT. Furthermore, under the restriction of cost, thermal conductivity threshold and LFT, the parameters of the feasible construction state areas of four different accelerators were compared; in this study AC3 was found to be the most appropriate accelerator.