Alternative methodology to consider damage and expansions in external sulfate attack modeling

Abstract

A diffusion -reaction numerical model is proposed to simulate the response of concrete exposed to external sulfate attack. Diffusion properties are modified based on the strain reached and the ratio of porosity filled by ettringite. A direct and intuitive approach is proposed for the consideration of the diffusion in a cracked porous media based on the constitutive law of the material. A methodology to compute expansions based on a more realistic consideration of the concrete porosimetry is presented, by which it is possible to distinguish different strain contributions from different pore sizes. The described approach also allows the consideration of different capacities to accommodate expansive product for each pore size considered and the faster filling rate existent in small pores. Critical parameters of the numerical model developed are recognized and

A new chemo-mechanical model of damage in concrete under sulfate attack

“…This process can be divided into two steps: 1) reaction between sulfate ions, SO 2À 4 , and calcium hydroxide, CH, to form gypsum, C SH 2 ; 2) reaction of gypsum with tricalcium aluminate, C 3 A, and water, H, to form delayed ettringite, C 6 A S 3 H 32 . Detail chemistry reaction equations are given as follows [4],…”

“…The mechanism for the sulfate attack on concrete matrix, however, is so complicated that it is still unclear till now. For instance, Tixier and Mobasher [3] and Ikumi et al [4] thought that a series of chemical reactions take place between sulfate ions and the unreacted hydration compounds of the cement paste, and all those reactions lead to degradation of concrete. Therefore, this challenge problem attracts many http://dx.doi.org/10.1016/j.conbuildmat.2016.04.074 0950-0618/Ó 2016 Elsevier Ltd. All rights reserved.…”

Feedback System of Ion Transfer through Cracks During Deterioration of Mortar Due to Sulfate Attack Evaluated by RBSM-Truss Network Model

“…Another approach is that, expansion rate is calculated by structural analysis introduced by expansion strain as initial strain (Idiart et al 2011). In addition, a model that provides a relationship between expansion strain and pore distribution was also proposed in order to consider that smaller pore diameter potentially has bigger expansion pressure (Schmid et al 1999a(Schmid et al , 1999bIkumi et al 2014). Furthermore, models that considered the change in diffusivity and mechanical behaviors after degradation were also developed.…”

“…In general, the proposed diffusionreaction model is composed of a mass transfer term and a reaction term. With regard to mass transfer modeling, diffusion model considers interaction of coexistence ion (Maltais et al 2004;Glasser et al 2008;Schmid et al 1999aSchmid et al , 1999b or brief diffusion model of sulfate ion (Krajcinovic et al 1992;Tixier et al 2003aTixier et al , 2003bIdiart et al 2011;Ikumi et al 2014). In addition, some 1 researcher take account for the effect of moisture transfer against sulfate attack in order to evaluate the influence of drying condition (Maltais 2004;Glasser 2008,).…”

“…In comparison, chemical reaction model can calculate the change in reactant and precipitation from molar ratio of chemical reaction equation. In this approach, chemical reaction is defined by certain minerals and sulfate ion, and reaction rate constant is set to fit in actual phenomena (Krajcinovic et al 1992;Tixier et al 2003aTixier et al , 2003bIdiart et al 2011;Ikumi et al 2014).…”