Events Calendar

The nanochemomechanics of geomaterials

Speaker: Alberto Ortega, Massachusetts Institute of Technology

Talk Title: The nanochemomechanics of geomaterials

Abstract: Geomaterials such as rocks, soils, and concrete have emerged as crucial components in advanced engineering solutions related to enhanced oil recovery, geothermal energy, carbon sequestration, and green construction materials. These engineering challenges demand an intimate understanding of the multiscale mechanical behaviors of natural and engineered porous composites. In this presentation, a combination of experimental and theoretical microporomechanics approaches deployed at fundamental material scales is proposed as a means to decode complex mechanical responses of two geomaterials: shale, a type of clay-bearing sedimentary rock, and a high-performance cement paste. For shale, experiments involving statistical grid nanoindentation and an original application of wave dispersive spectroscopy allowed for the proper chemomechanical quantification of the in situ clay matrix response and the nature of the clay-silt grain interface. The micromechanics modeling of the clay matrix as a composite of nano-sized building blocks of clay agglomerates and nanoporosity revealed a granular and anisotropic mechanical behavior, which drives the poroelasticity of shale observed at macroscopic scales. For cement, the intrinsic solid properties of the calcium silicate hydrate (C-S-H) phase in high-performance pastes were determined by employing a similar experimental program and the micromechanics modeling tools. The improved elasticity and strength of the solid backbone compared to those of ordinary cement pastes provided valuable insight into the effects of mix design and curing on the mechanical response of the hardened materials. The nanochemomechanics of these geomaterials learned from fundamental scales can be used as instrumental information for the design and validation of upscaling models capable of predicting macroscopic engineering properties. Furthermore, the proposed geo-genome approach represents a viable framework for the mechanical modeling of other natural porous composites.

Host: Sonny Astani Dept. of Civil and Environmental Engineering

Location: Kaprielian Hall (KAP) - 209

Audiences: Everyone Is Invited

Contact: Erin Sigman