Formulação numérica para simulação de sistemas de pós-resfriamento em estruturas de concreto massa

Resumo

Due to the high costs and safety requirements of construction and infrastructure works, thermal cracking
of young concrete has been a concern of the engineering community since the first applications of mass concrete.

The heat generation during hydration and the consequent increase in the temperature of the concrete are very im-
portant, not only because they can generate thermal gradients in space and time, responsible for the appearance of

high initial stresses, but also because deleterious phenomena such as the formation of delayed etringite formation
(DEF) have been shown to be associated with the existence of thermal fields in the early ages of cementitious
material. In this way, many actions can be taken to minimize the appearance of undesired stresses, such as: (i)
decrease in construction speed; (ii) reducing the casting temperature of the concrete; (iii) lowering the temperature
using a post-cooling system; (iv) choice of a low heat hydration composition. This work will discuss the numerical
implementation of a concrete post-cooling model, in which the temperature of the concrete during hydration is
reduced by the circulation of water or air in pipes embedded in the formwork (postcooling systems). Numerical
modeling of the post-cooling of concrete allows significant savings in the construction of large structures. Thus,

developing a predictive cracking model, which incorporates concrete cooling in the early ages, is extremely impor-
tant to minimize the appearance of stresses that exceed the resistive capacity of the element and future pathologies.

In this work, a numerical formulation is presented for a simulation model of the cooling system with tubes in mass
concrete structures, on a mesoscopic scale, to be implemented and coupled in a DAMTHE finite element model,
developed in FORTRAN programming language, by PEC / COPPE / UFRJ.