Activation Energy for the Concrete Maturity Model – Part 2: New Model for Temperature Dependent E_a

The article addresses the modelling of the maturity of concrete. The apparent activation energy is the backbone of the Arrhenius model, which is typically used to model the maturity of concrete. The maturity (or the equivalent age) is influenced by the curing temperature and it is applied when modelling the hydration process and the hardening of concrete for instance in order to forecast the early-age strength to determine the time for removal of formwork or the time for prestressing. Part 1 of the article describes the background for the maturity model and the tests carried out as part of a large test programme at the DTI concrete lab. The tests were applying iso-thermal curing temperatures from 5°C to 60°C for various durations before measuring the compressive strength.

Part 2 of the article presents a model for the activation energy based on these test results. An alternative formulation of the maturity model is suggested and compared with other similar concrete tests found in the literature for early-age strengths. The alternative model is shown to give better accuracy when modelling the early-age strengths of concrete. The tests include five different concretes, using three different cement types and the addition of fly ash.