Effects a simplified numerical model for temperature profiles 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 a confinement for discrete elements. Due to complexity of the issue, designers currently rely on mock tests and/or finite element modelling mostly 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 the concrete elements. The proposed spreadsheet-based model reported 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 is validated based on measured temperature development of a rectangular section concrete block. Further, the proposed model is successfully compared with output from finite element software TNO Diana.