Legacy

The central problem of mass concrete, tied to its own definition, is the need to control the potential for thermally induced cracking. The mechanics can be made as complex as one wishes: constitutive models are literally endless. Concrete may be treated as a chemically reactive porous medium; continuum mechanics may be extended (continuum–discontinuum, fracture); concrete may be modelled as a heterogeneous material, including across N scales. Specialization and sometimes insight are gained, yet the overall view and applicability are lost — including a viable (cost) and feasible (schedule) test matrix for a real project accepted by all stakeholders.

The purpose of the Legacy project is to recover, understand, update and make available: keep what is essential, and add what is relevant and practical from a cost and schedule standpoint.

What enters Legacy from what was done before:

• internal heat generation, with a more accurate understanding of thermal activation and of other tests available today;
• thermal properties and the expansion coefficient, as before: invariant with degree of hydration and temperature, and a homogeneous material;
• elastic modulus and creep, in the basics, as before; yet here understanding can advance, because much has been developed in this area. Even with the same tests as before, it is not only possible, viable and feasible today — it is even straightforward — to represent the compliance function by a thermodynamically admissible model that prevents negative relaxation, covers drying, and is flexible from the shortest to the longest decades, beyond the test window;
• autogenous shrinkage, as before, in the basics. Recognizing, however, that advances in the drivers of chemically induced deformation, knowledge of the influencing factors and the options for controlling it with special admixtures and new additions have widened the spectrum for this important variable. Mechanically, though, it remains the same as before.

All of these properties and factors converge on what we commonly call:

• thermal analysis PT · EN — in preparation
• calculation of thermally induced stresses PT · EN

What the Legacy project aims to contribute is to fill what we see as a gap: within what is linear, isotropic, homogeneous and time-invariant in the constitutive sense adopted here, it is possible to establish the correct response. An analytical–numerical validation that is the gold standard in computational modelling. An international effort has already been made in that direction (TUCOST1404) and, from internal developments allied to work funded by ANEEL and FURNAS, we can now return to the technical community — as a form of societal return — the experience accumulated over decades of services and research.

That is what we call recovering: making available a Technical Memory that remains useful. What the masters did with the tools of their time from analytical solutions and practical criteria, updated with part of the state of the art in thermomechanical modelling, made available in a usable and reproducible way.