Multiscale modeling of ion transport and ASR induced damage in concrete structures

Abstract

Alkali-Silica Reaction (ASR) is a detrimental expansive reaction in concrete structures, such as dams and pavements, which substantially limits their structural lifetime. Silica present in the so-called "reactive" aggregates reacts with calcium, hydroxyl and alkali ions of the pore fluid to form a hydrophilic alkali-silica gel. The gel fills pre-existing microcracks in the aggregates and the cement paste and swells in the presence of moisture. The gel pressure induced microcrack growth manifests itself as an expansion at the macroscale. The so-called slow-late ASR damage mechanism initiates at the aggregate scale, leading to concrete degradation in the form of microcracks, which starts in the aggregates and eventually propagates into the cement paste. In order to predict damage and expansion profiles in a concrete pavement a multiscale approach is adopted. The microcracking process that is characterized by linear elastic fracture mechanics and microporomechanics is upscaled by means of mean-field homogenization. Moisture and alkali transport in intact and damaged concrete at the macroscale as well as the diffusion of alkali ions into the aggregate at the microscale is also considered in the model to account for the influence of external alkali and moisture supply on the durability of concrete pavements. The capabilities of the multiscale chemo-mechanical model at different scales are illustrated by comparison with experimental measurements.

Reduced Order Multiscale Simulation of Diffuse Damage in Concrete

“…The derived parameters for the quartzitic aggregates are 146 in line with data from the literature [58], whereas the compressive strength is slightly 147 smaller (90 GPa) and Poisson's ratio slightly larger (0.10) as compared to α-Quartz. In order to model distributed microcracking in the mortar material, we adopt the 197 multiscale concrete model proposed in [23]. The model is based on the synthesis of 198 continuum micromechanics and Linear Elastic Fracture Mechanics (LEFM) (see [28]).…”

“…After a converged microcrack radius is computed, the reduced effective stiffness (taken from [22]) and 84.6 GPa, respectively. The Poisson ratio of sand inclusions is 230 assumed to be 0.2 [23]. The model parameters including the geometrical parameters are 231 chosen within the range proposed in [23].…”

“…The Poisson ratio of sand inclusions is 230 assumed to be 0.2 [23]. The model parameters including the geometrical parameters are 231 chosen within the range proposed in [23].…”