Air-void size distribution of cement based foam and its effect on thermal conductivity

The study reported here characterizes the air-void size distribution in cement-based foam and examine its influence on thermal conductivity, density, and pozzolanic admixture. The cement-based foam was produced by replacing fly ash, silica fume, and metakaolin, up to 20% by weight, for densities range of 800-400 kg/m3. Through, X-ray tomography technique the air-void distribution was evaluated while the thermal conductivity was measured using the transient plane source. The study results revealed that the air-void diameter of size 0.03 mm was optimal for all the mixes. Further, it was found that with an increase in the cast density, there was a drop in the median void diameter (D50) and for given density, the thermal conductivity decreases with an increase in the median void diameter. In addition, the data showed that the influence of pozzolanic admixture on the air-void size distribution was not significant.