Insulating behavior of metakaolin-based geopolymer materials assess with heat flux meter and laser flash techniques

Thermo physical behavior of metakaolin-based geopolymer materials was investigated. Five compositions of geopolymers were prepared with Si/Al from 1.23 to 2.42 using mix of sodium and potassium hydroxide (similar to 7.5 M) as well as sodium silicate as activator. The products obtained were characterized after complete curing to constant weight at room temperature. The thermal diffusivity (2.5-4.5 x 10(-7)m(2)/s) and thermal conductivity (0.30-0.59 W/m K) were compared to that of existing insulating structural materials. The correlation between the thermal conductivity and parameters as porosity, pore size distribution, matrix strengthening, and microstructure was complex to define. However, the structure of the geopolymer matrix, typical porous amorphous network force conduction heat flux to travel through very tortuous routes consisting of a multiple of neighboring polysialate particles.