A simplified numerical model for the temperature profile of early-age concrete

Abstract

The issue of early-age concrete cracking is challenging and relies on the state of concrete soon after it is placed in the formwork. The concrete state is a function of the strains associated with thermal and other dilatations and the level of in situ strength. Both strain and strength primarily require information on the temperature–time history of the concrete element. For larger elements, the thermal history varies significantly across the thickness and the concrete material itself acts as confinement for discrete elements. Due to complexity of this issue, designers currently rely on mock tests and/or finite-element (FE) modelling for structures that are deemed ‘important’. Both approaches are costly and time consuming. It is therefore important to have a robust yet simple model to estimate the temperature variation experienced by concrete elements. The proposed spreadsheet-based model presented in this paper aims to provide a rapid estimate of the temperature profiles within a hydrating concrete element. The model uses the concept of effective thickness and the revised heat compensation technique. It was validated based on the measured temperature development of a concrete block of rectangular section. The proposed model was also successfully compared with output from FE software (TNO Diana).