Microporomechanics study of anisotropy of ASR under loading

Abstract

International audienceIn this article, we introduce a new micromechanical model for alkali-silica reaction. Our idea was to build a model with the following characteristics. First, the model has to be simple enough to be used to compute damage under loading and chemical attack at the level of each element in a structure code. Second, its parameters must be easy to identify on available alkali-silica reaction lab experiments. We have chosen to model the behavior of concrete containing aggregates such that most of the damage occurs in the cement paste. Using micromechanics and an energy criterion, the model remains analytical except for the minimization of the energy. The parameters were identified on Multon's triaxial experiments and good results were obtained for compressive loadings up to 10 MPa. ?? 2014 Elsevier Ltd

The mechanism of limited inhibition by fly ash on expansion due to alkali–silica reaction at the pessimum proportion

“…Many previous models assume that ASR expansion takes place at the rim, similar to a surface reaction [28,34,35]. There have been arguments against analysis based on such an assumption, in that it does not realistically reflect the reaction [36][37][38].…”

Expansion modelling based on cracking induced by the formation of new phases in concrete

“…the Biot Modulus related to the inclusions, , the volumetric fraction of porosity filled by the inclusions related to the skeleton deformation [23]. It can be assessed from the growth of the new phases in relation to crystallization pressure [12], [13], [23] or to the volume produced by chemical reaction [14], [26].…”

“…For simplicity, the Biot coefficient is evaluated in a linear context here, from the mechanical properties and volumes of inclusions (Equation (5)) without consideration of the shape of the porosity filled by the new phases. More precise quantification could be obtained by taking account of the shape of filled cracks as proposed in [26], [27], [40]. In the present work, the non-linearity due to the combination with diffuse cracking caused by pressure, creep [41] and structural damage [42] is considered differently, by resorting to damage theory [53].…”

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

“…It is a pressure-based model, based on the microporomechanics theory developed by Dormieux et al (2006). A similar approach was previously adopted by Lemarchand et al (2005) and by Charpin and Ehrlacher (2014) to describe, respectively, the expansion behaviour of ASR-affected concrete in free-expansion and under confined conditions, without concern-4 ing for the mechanical degradation of concrete. The model presented in this paper aims to describe the deteriorating impact of ASR on concrete in terms of the relation between the induced expansion and the degradation of mechanical properties.…”