Mechanics and Electrochemistry of Charged Porous Media

Modeling and experimentation on cement, colloids, and other charged porous materials to improve infrastructure resilience, sustainability, and functionality

A brief description of our research interests

The lab seeks to understand and model the mesoscopic assembly and mechanical performance of reactive materials that are important to our built environment; the transport of charged molecules and colloidal species through heterogeneous porous media; and the interaction between electrochemical solutions and the confining pressure of solids. Progress should enable new routes to optimize durable and eco-friendly designs of infrastructure materials, novel means of energy storage, and an enhanced understanding of the physics governing messy charged media in civil engineering applications. We aim to translate tools from electrochemistry and soft matter physics to cement and geomaterials to better understand chemical transport, microscopic organization, and mechanical behavior, utilizing data collected in experiments or in literature to validate predictions from our theory and models and identifying routes toward the preferred mesoscopic organization or composite assemblies that optimize the desired material trait and/or provide new functionality.

Here are two sample questions that interest us:

How do geopolymers and colloidal cement particles aggregate and rigidify in a changing chemical environment? As we are now able to synthesize stable calcium-silicate-hydrate (C-S-H - the phase in cement that lends the material its cohesion) particles in solution, micro- and nanofluidic experiments offer a promising route to understanding aggregation mechanisms in precisely controlled electrochemical environments.
How are the precipitation, aggregation, and ordering of colloidal and polymeric materials affected by their surrounding chemical environment? How do their hierarchical organizations influence their elasticity, toughness, and internal stress development? By extending phase-field descriptions to include electrostatic effects and incorporating the anisotropy of small-scale building blocks, combinatorial techniques and computer-aided design are hoped to improve our ability to translate observations made on the small scale (often nanometers) to the continuum micromechanical and macroscopic scales.
What controls the conductivity and capacitive properties of composites made of cement and carbon particles? It has been shown that carbon particles mixed into cement and saturated in an electrolyte can create composite electrodes capable of storing appreciable quantities of energy as a supercapacitor. We aim to measure how the organization of these constituents modifies charging-discharging rates and optimizes the energy-storing capabilities.

To achieve these research objectives, the lab is building experimental capability in measuring the transport properties of interacting colloidal particles - such as clays and varying geopolymers and nanocrystals - in microfluidic systems and mixing cement composites using differing conductive binders and inclusions. Experimental findings on the scale of micrometers and millimeters will be modeled using non-equilibrium thermodynamic theories, such as phase-field modeling and density functional theory. The goal is to connect microscopic ordering to property development at the bulk scale and identify levers to tune properties.

Non-equilibrium thermodynamic phase-field models recreate density patterns experimentally observed in various, kinetically arrested gel systems.

Brownian particles moving through a charge-patterned nanopore.

Ion layering between two charged mineral surfaces. Classical density functional theory is used to predict the distributions of water molecules, cations, and anions, and disjoining pressure between charged, textured interfaces.

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