Pore network and microstructure in the prediction of heat flux transport in sponge-like geopolymers for thermal insulation.

A microstructural approach to the prediction of heat flux transport in porous geopolymers is used experimentally to understand the effects of the pore size distribution and pores connectivity to the transfer of the thermal flux across the porous network of geopolymers. Controlling the mix design and the concentration of porogen agent, capillary pores can be introduced into the system for a final homogeneous microstructure. The roundness of pores, their geometrical distribution, and their connectivity allow the possibility to extend the length of the pathway of the tortuous route for potential heat flux. The nonlinear relationship between tortuosity–porosity and tortuosity–thermal conductivity confirms that the volume of pores is not the only parameter affecting the heat flux transport. The results achieved in terms of homogeneous microstructure with geometric description of pore, their level of isolation, and the spatial distribution allow the prediction of the heat flux transport in environmentally friendly and sustainable porous geopolymer materials. [ABSTRACT FROM AUTHOR]