Macro and meso analysis of cement-based materials subjected to triaxial and uniaxial loading using X-ray microtomography and digital volume correlation

• Published in: Construction & building materials Vol. 323; p. 126558
• Main Authors: Lorenzoni, Renata, Lima, Victor Nogueira, Figueiredo, Tathiana Caram S.P., Hering, Marcus, Paciornik, Sidnei, Curbach, Manfred, Mechtcherine, Viktor, de Andrade Silva, Flávio
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 14.03.2022
• Subjects: Cementitious materials; Digital volume correlation; ex-situ microCT; Porosity; Triaxial test; Digital volume correlation; Triaxial test; Porosity; ex-situ microCT; Cementitious materials
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2022.126558

•Young's modulus and Poisson's coefficient decrease with increasing confinement.•Increase in ductility and strength was observed for higher confinement.•DVC shows that cracks tend to occur in ITZ.•Aggregates displace less within the cement paste when increasing confinement. Considering that structures destined for civil construction are commonly subjected to confinement loadings, triaxial testing is already standard for the characterization of cementitious materials, and novel methods to validate or explain the macro mechanical responses are needed. Since the macro behavior is linked to the behavior of the meso and microstructure of the material, the development of analysis methods at these scales is required. MicroCT technique provides 3D images in mesoscale that can bring relevant materials information when coupled with mechanical tests. This study presents the results of ex-situ microCT tests on cementitious materials subjected to uniaxial and triaxial loading. Cement pastes and concretes were tested in triaxial compression under 0, 10 and 20 MPa confining pressures. The macro mechanical responses could then be correlated with the material meso behavior through microCT images. For instance more significant meso structural changes were noticed with an increasing level of confinement. The digital volume correlation technique was applied to obtain the strains when a regular concrete was subjected to uniaxial and triaxial tests. Information such as the strain levels of aggregates within the cementitious matrix and the cracking pattern were obtained. For example, it was found that the aggregates present higher relative displacement within the cement paste when there is no confinement.