Chemical modelling of Alkali Silica reaction: Influence of the reactive aggregate size distribution

Abstract

International audienceThis article presents a new model which aims at the prediction of the expansion induced by Alkali Silica Reaction (ASR) and the description of the chemical evolution of affected concretes. It is based on the description of the transport and reaction of alkalis and calcium ions within a Relative Elementary Volume (REV). It takes into account the influence of the reactive aggregate size grading on ASR, i.e. the effect of the simultaneous presence of different sized reactive aggregates within concrete. The constitutive equations are detailed and fitted using experimental results. Results from numerical simulations are presented and compared with experiments.Cet article présente un modèle qui a pour but la prédiction du gonflement induit par la réaction alcali-silice et la description de l'évolution chimique des bétons affectés. Il est basé sur la description du transport et de la réaction des alcalins et des ions calcium dans un Volume Elémentaire Représentatif. Il permet notamment de tenir compte de l'influence de la granulométrie réactive, c'est-à-dire de l'influence de la présence simultanée de granulats réactifs de différentes tailles dans le béton. Les équations constitutives du modèle sont détaillées puis calées à partir de résultats expérimentaux. Les résultats des simulations numériques sont présentés et comparés aux valeurs expérimentales

A multiscale micromechanical approach to model the deteriorating impact of alkali-silica reaction on concrete

“…The study of the chemical process which leads to the swelling of the gel and the expansion of concrete was the focus of the last two decades. Model based on the diffusion and reaction of the ions were first developed in a mathematical framework (Bažant and Steffens, 2000;Suwito et al, 2002;Liuaudat et al, 2014) and subsequently implemented in finite element software to describe the mechanical impact (Poyet et al, 2007;Multon et al, 2009;Sanchez et al, 2014;Alnaggar et al, 2013).…”

“…The study of the chemical process which leads to the swelling of the gel and the expansion of concrete was the focus of the last two decades. Model based on the diffusion and reaction of the ions were first developed in a mathematical framework (Bažant and Steffens, 2000;Suwito et al, 2002;Liuaudat et al, 2014) and subsequently implemented in finite element software to describe the mechanical impact (Poyet et al, 2007;Multon et al, 2009;Sanchez et al, 2014;Alnaggar et al, 2013).To understand the evolution of ASR in concrete and its degradation impact on the material, in this paper a multiscale material model is proposed.The model ranges from the aggregate level (also known as meso level) to the concrete level. It is a pressure-based model, based on the microporomechanics theory developed by Dormieux et al (2006).…”

Elastoplastic-Damage Compression Constitutive Model for Cementitious Material Subjected to Alkali-Silica Reaction

“…It is assumed that the damage of concrete is isotropic (Poyet et al 2007). The damage consists of tensile and compression damages, whose mechanisms and effects are different from each other.…”

“…Based on chemical and damage mechanics theories, a series of models was proposed to predict the expansion with the evolution of ASR (Poyet et al 2007;Multon et al 2009;Bazant and Steffens 2000). In these models, the parameters considered mainly included alkali and reactive silica contents, aggregate sizes, mechanical properties of the mortar, temperature and humidity, etc.…”

Combined Action of Mechanical Pre-Cracks and ASR Strain in Concrete

“…The presence of such water in concrete may feed and accelerate the ASR process and associated deterioration. Several methods are now available for diagnosing the presence of an alkali-aggregate reaction in concrete experimentally such as, ASTM C 1260ASTM C (2007 and ASTM C1293 (2008), or by chemically or chemo-mechanically modelling (Poyet et al 2007;Ichikawa 2009;Multon et al 2009;Charpin and Ehrlacher 2012;Garcia-Diaz et al 2006;Bazant and Steffens 2000) and there are many methods to investigate the mechanical effects on the concrete, such as coring and determination of mechanical properties of stiffness and strength. However, researchers to date have not clarified the behaviour of ASR-affected concrete after formation of a mechanically-induced crack, which is believed to give important information for intervention strategies.…”