A model for predicting thermal conductivity of concrete

Abstract

This study investigates the thermal conductivity of fly ash concrete. Experiments were conducted to obtain the thermal conductivity of fly ash–cement pastes and mortars. Pastes were prepared to investigate the effect of fly ash, and mortar specimens were prepared for studying the effect of aggregates. It was found from the test that the replacement of cement by fly ash resulted in lower thermal conductivity. Thermal conductivity of mortar was higher than that of the cement paste. A simple parallel model for predicting thermal conductivity of fly ash concrete was proposed as a time-, material- and mix-proportion-dependent function. Thermal conductivity of concrete was computed based on the volumetric fractions and respective thermal conductivity values of each ingredient including the hydrated and pozzolanic products. Thermal conductivity of all ingredients in concrete are obtained from other studies except for the fly ash powder and hydrated products. In this study, thermal conductivity of hydrated product was obtained by the use of regression analysis together with the test results of cement paste, and thermal conductivity of fly ash powder was derived from the test results of cement–fly ash paste. The model was satisfactorily verified with various experimental results for pastes, mortars and concretes.