Effect of Pozzolanic Admixtures on Thermal Properties of Lightweight Cement-Based Foams

This experimental study was conducted to investigate the effect of pozzolanic admixtures on the thermal conductivity of lightweight cement-based foam (LW-CBF). The foam mixes were cast and tested for three different densities namely, 800, 600, and 400 kg/m3. Three different pozzolanic admixtures namely, fly ash, silica fume, and metakaolin, were examined here. Fly ash was incorporated at up to 50 % mass substitution of cement, while silica fume and metakaolin were incorporated in the binder at up to 20 % replacement by cement mass. Density, moisture content, and thermal conductivity were measured experimentally, while porosity was evaluated theoretically. The transient line source (TLS), which conformed to ASTM standards, was used to assess the thermal conductivity in this study. It was found that the thermal conductivity of the cement-based foam samples was proportional to the cast density in the range examined with, on average, a 20 % drop in conductivity between 800 and 400 kg/m3. In addition, it was found that adding pozzolanic admixtures resulted in a higher moisture content. Furthermore, of the three pozzolanic admixtures, silica fume was the most efficient, causing a 30 % drop, whereas metakaolin was the least at a mere 10 % decline for equal dosage.

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