A method for measuring transient thermal diffusivity in hydrating Portland cement mortars using an oscillating boundary temperature

The transient thermal diffusivity in early‐age, type I Portland cement mortars is difficult to quantify because the exothermic reactions cause significant heat generation which complicates the analysis of heat transfer. This paper outlines the theory and setup for a method of determining the transient thermal diffusivity of Portland cement mortars by forcing an oscillating temperature on one side of the material and measuring the attenuation of the temperature oscillation with distance. This experimental method also controls temperature to acquire data over a specific and narrow temperature range. The method is illustrated using computer models and laboratory experiments on wet and dry sand and Portland cement mortar. The values of thermal diffusivity of sand and mortar determined by this method correspond well to values found in literature. This general method could be applied to other materials, including cement paste, concrete, reactive solids, or biological tissue with appropriate modification to the apparatus.