Operational implementation of concrete thermal modeling for construction projects

Abstract

Estimating delayed ettringite formation risks, early age cracking and/or early age strengths in concrete structures is still a complex task to achieve in construction projects. Indeed, numerous complex coupled phenomena occur during concrete hydration process, which must be finely described for accurate predictions of these different criteria. It requires the determination of various input data, which leads to various experimental tests (calorimetry, mechanical properties, temperature records, both chemical, and physical concrete constituent properties) which are not fully available for industrial practices. Therefore, since more than a decade Vinci Construction Grands Projets focuses on modeling and numerical simulations which allows transferring both construction project feedbacks and internal research investigations to our next industrial applications in the form of methodology and internal recommendations. Different representative examples from successful experienced projects illustrate this methodology and draw the main relevant key features to optimize construction processes. This paper shows that predicting the evolution of thermophysical properties of concrete from its mix design at the macroscopic scale allows an accurate temperature prediction in concrete structures when the used model correctly captures the key phenomena such as the thermo-activation process based on the full detailed "Methodology." For the prediction of DEF and thermal cracks risks, the associated project requirements inherited from technical guides and relevant standards have been employed to help construction teams to optimize their construction options and associated planning in the most safely conditions.

Modeling of Heat Transfer in Massive Concrete Foundations Using 3D-FDM

“…Other researchers noticed that concrete's thermal properties are not affected by age and that the type of coarse aggregate has a great effect on conductivity, while the original water content has less effect [19]. In mass concrete elements, concrete thermal modeling gives designers and contractors the opportunity to estimate the elevation of temperature within concrete elements before pouring, which allows them to adapt their construction and production techniques to handle and manage these circumstances [20].…”

“…Several researchers [13,20,21] mentioned different techniques that can be used to minimize the thermal gradients and peak temperatures as well, like cooling the concrete components to reduce the concrete's initial temperature, selecting convenient aggregates with a low coefficient of thermal expansion, using modified or low-heat cement, using nitrogen cooling, pipe cooling, insulated formwork, or using thermal blankets to insulate the concrete element. These are the most effective and economical precautions that can be implemented to control early-age cracking [22,23].…”