Modeling Time-Dependent Behavior of Concrete Affected by Alkali Silica Reaction in Variable Environmental Conditions

Abstract

Alkali Silica Reaction (ASR) is known to be a serious problem for concrete worldwide, especially in high humidity and high temperature regions. ASR is a slow process that develops over years to decades and it is influenced by changes in environmental and loading conditions of the structure. The problem becomes even more complicated if one recognizes that other phenomena like creep and shrinkage are coupled with ASR. This results in synergistic mechanisms that can not be easily understood without a comprehensive computational model. In this paper, coupling between creep, shrinkage and ASR is modeled within the Lattice Discrete Particle Model (LDPM) framework. In order to achieve this, a multi-physics formulation is used to compute the evolution of temperature, humidity, cement hydration, and ASR in both space and time, which is then used within physics-based formulations of cracking, creep and shrinkage. The overall model is calibrated and validated on the basis of experimental data available in the literature. Results show that even during free expansions (zero macroscopic stress), a significant degree of coupling exists because ASR induced expansions are relaxed by meso-scale creep driven by self-equilibriated stresses at the meso-scale. This explains and highlights the importance of considering ASR and other time dependent aging and deterioration phenomena at an appropriate length scale in coupled modeling approaches.

Discrete element framework for modeling tertiary creep of concrete in tension and compression

“…The model following the rheological representation of Figure 1 splits the total strain rate,˙ tot , into different strain rates that describe different physical mechanisms. These are an instantaneous response, * described by a non-aging spring plus the strain rate due to damage, dam , which are determined from LDPM, viscoelastic response,˙ v , represented by a non-aging Kelvin chain with typically ten elements in combination with an aging function formulated in terms of reaction degree [45,46]. Additionally, the model accounts for the pure viscous flow,˙ f , using an aging dashpot calculated from the Micro-Prestress theory [45,46].…”

The Linear Hygroscopic Expansion Coefficient of Cement-Based Materials and Its Determination

“…Similar to the definition of the CTE [23][24][25], the CHE can be defined as the volume change or length change caused by the change of the humidity unit inside a material; these changes can also be called the volume hygroscopic expansion coefficient (VCHE) and the linear hygroscopic expansion coefficient (LCHE), respectively. For convenience, relative humidity (ϕ) can be chosen to describe humidity or moisture.…”

Proper Orthogonal Decomposition Framework for the Explicit Solution of Discrete Systems With Softening Response

“…Lattice discrete particle model is implemented in a computational software named MARS [47] and was used successfully to simulate concrete behavior in different types of laboratory experiments [45]. Furthermore, LDPM has shown superior capabilities in modeling concrete behavior under dynamic loading [28,48], alkali silica reaction deterioration [49][50][51], fracture simulation of fiber reinforced polymers (FRP) reinforced concrete [52], failure of fiber-reinforced concrete [53][54][55], and early age behavior of ultra high performance concrete [30,56,57]. LDPM was also recently formulated to simulate sandstone [58], shale [31,59], and waterless concrete [29].…”