Evaluation of thermal conductivity of cement-based foam reinforced with polypropylene fibers

This study quantifies the results of the thermal conductivity for cement-based foam reinforced with polypropylene fibers and correlates the influence with pozzolans, porosity, moisture content, and pore parameters. Here, the mixtures were prepared for the densities range of 400-800 kg/m(3) in which cement was replaced in the ratios of 10% and 20% (by weight) with fly ash, silica fume, and metakaolin. Along with pozzolan, polypropylene micro-fibers were added at the volume fraction of 0.2%. The thermal conductivity was measured variously at the hydration age of 60-210 days by using the transient plane source technique. While the porosity and the pore parameters were evaluated by using X-ray microtomography, a non-destructive technique. The results revealed that polypropylene fibers contributed to reducing the conductivity and among the three pozzolans, fly ash was the most efficient. However, the porosity increases with the inclusion of fibers but drops significantly with the addition of pozzolans, especially for lower densities mixtures. Also, it was found that D50 relates linearly with conductivity. However, based on experiment results, a modified thermal conductivity predictive model for cement-based foam reinforced with fiber was developed.