Methodology of Evaluating Elastic Modulus of Cement Mortar Corroded in Brine

Abstract

This article creatively established a four-stage methodology to evaluate the macroscopic elastic modulus of the cement mortar corroded in brine solution. At first, the nanoindentation technique was utilized to measure the microscopic elastic moduli of a 10 × 10 lattice locating on a region containing sand aggregates, cement paste and interface transition zone (ITZ). The compositions and contents of each point were determined by XRD combined with SEM-EDS. Secondly, three different thicknesses (5 µm, 10 µm and 15 µm) of the ITZ were assumed and the corresponding microscopic elastic moduli were calculated based on porosities from imaging process, multi-scale homogenization method and the Voigt parallel mode. The thickness of the corroded ITZ was then determined. Moreover, the Lu & Torquato model was used to calculate the volume fractions of cement matrix, aggregates and ITZ of the mortar, treated as important parameters to predict the macroscopic elastic moduli of corroded and non-corroded mortar with homogenization method. Finally, a Reuss-Voigt equivalent approach was proposed to calculate the macroscopic elastic modulus of the mortar, which showed good agreement with the measured macroscopic elastic modulus from uniaxial compression test. Therefore, the methodology utilized to evaluate the macroscopic elastic modulus of the corroded cement mortar is effective.