Swelling behavior of ion exchange resins incorporated in tri-calcium silicate cement matrix: II. Mechanical analysis

Abstract

International audienceThis paper presents the second part of a study aiming at modelling the mechanical behavior of composites made up of ion exchange resins (IER) solidified in a tri-calcium silicate cement paste (C3S). Such composites may be subjected to internal pressures due to ion exchange processes between ionic species which are in IER and interstitial solution of the cement paste. The reactive transport model developed in the companion paper is coupled in this study to a multi-scale approach describing the mechanical behavior of the material. It is based on an analogy with thermomechanics for taking in account the IER internal pressures, and on Eshelby-based homogenization techniques to estimate both mechanical and coupling parameters. A laboratory test has been set up to measure the macroscopic strain caused by the swelling phenomenon. The model has been finally implemented in a finite elements software. The simulation of the laboratory tests has been performed and the results have been analyzed and compared to experimental data

Swelling behavior of ion exchange resins incorporated in tri-calcium silicate cement matrix: I. Chemical analysis

“…However the discontinuity of the shell is taken into account through an interaction coefficient in the companion paper [24]. Thus, with this hypothesis, the average volume Vl SCH of one continuous shell of portlandite might be calculated with the following equation.…”

“…Ts IER ðtÞ ¼ k tps $n ech ðtÞ (20) where k tps is a kinetic coefficient which is identified and adjusted numerically on experimental results by means of a back analysis [24]. Indeed the ion exchange is supposed to be controlled by a basic first order-like kinetic law with constant kinetic coefficient.…”

“…The simulations have been realized on a sample of C 3 S/IER-Ca immerged in a 5 L solution containing 0.5 mol/L of: NaOH, which corresponds to a test where strain has been measured during an immersion in sodium hydroxide [24]. Moreover a comparison could be done with the microstructure observed on Fig.…”

“…4. They correspond to quarter of the sample C 3 S/IER-Ca which is used for the experimental displacement measurement during the immersion in NaOH [24].…”

“…They focus on two configurations: (i) a system in which the sample is immersed in a solution leading to a full degradation of the material and (ii) another where no mechanical degradation has been observed. The modeling of the mechanical behavior due to chemical phenomena is the subject of a companion paper [24].…”