Chemical and Creep Models Applied to Concrete Damaged by Alkali–Silica Reactions

Abstract

Concrete structures that experience internal swelling reactions are often affected by other deleterious mechanisms, such as creep and shrinkage. In Brazil and many other countries around the world, numerous cases of building foundations and concrete dams were investigated due to the damage associated with internal expansions. Macroscopic models for the numerical representation of these expansions must take into account the influence of key environmental parameters such as temperature, degree of saturation, and the rate of development of the chemical reaction. To be relevant in structural applications, concrete creep models must consider several important phenomena, such as non-linearity, multi-axiality, and thermal and drying effects. In order to prevent these pathologies, to plan rehabilitation work, and to develop new design procedures, numerical simulation using the finite element method (FEM) is a very useful tool. This work aimed to implement a chemical model to simulate the advancement of the internal expansion reactions and a mechanical model to simulate creep and shrinkage phenomena in COMSOL Multiphysics® to reassess concrete structures suffering from these mechanisms. Both models were implemented separately to evaluate their responses and compare them with the theoretical results and experimental benchmarks proposed by the developers of these models. The numerical results obtained presented an excellent agreement with the experimental results, with a deviation of less than 10%, which showed that the implementation of the developed numerical models was very efficient. Moreover, this research holds significant importance as the mathematical models used to simulate internal expansions in concrete are currently only available in limited-use FEM software’s. Therefore, demonstrating the successful implementation of these models in widely used finite element programs and their ability to produce reliable results would be a valuable contribution.

Keywords

• concrete
• COMSOL Multiphysics^®
• creep
• internal swelling expansions
• numerical simulation
• shrinkage