Effects of Modern Concrete Materials on Thermal Conductivity

Abstract

Thermal conductivity, k, is one of the key factors that control heat transfer in concrete. This paper presents the results of an experimental study conducted to analyze the effects of modern concrete materials, such as supplementary cementitious materials (SCMs), normal-weight, lightweight, and recycled aggregates, and steel and polypropylene (PP) fibers, on the thermal conductivity of concrete. The thermal conductivity tests were performed on cylindrical specimens of concrete mixes containing various amounts of these materials. The results indicate that k values of concrete reduced with the amount of SCM (slag and fly ash) replacement for cement. The mineralogy and absorption of normal weight aggregate considerably affect k value of concrete. Replacing normal weight coarse aggregate by lightweight or recycled aggregate reduced the k value of concrete. Addition of steel fiber at a dosage higher than 0.25% (by volume) increased k value of concrete noticeably, whereas the addition of up to 2% PP fiber showed little effect.