Multifunctional Cement & Clay Composites
Engineering mesoscopic texture and mechanics for multifunctional construction materials
This thrust investigates microstructure evolution in cement and clay composites using optical and fluorescent microscopy, guided by phase-field (PF) theory. We explore arrested phase separation to generate distinguishable microstructural domains in cement systems, and investigate the organization of Laponite clay as an analog system.
Motivation
Controlling phase separation during cement hydration enables multifunctional construction materials that retain structural load-bearing capacity while providing secondary functions such as electrical conductivity or thermal regulation. Potential applications include:
- Structural supercapacitors
- Thermally adaptive pavements
- Electrokinetic sensing materials for infrastructure monitoring
Both Laponite clay and calcium-silicate-hydrate (C-S-H)—the primary binding product in cement—are nanoscopic colloids. This analogy allows us to investigate electrochemically driven phase behavior in well-controlled microfluidic experiments that inform cement design.
Key Innovations
Using hydrogel templates, we impregnate scaffolds with weakly miscible mixtures of water, propylene carbonate, and conductive nano-carbon black particles. By controlling crosslinking during phase separation, the hydrogel elasticity dictates the wavelength of the resulting bi-continuous domains. Initial experiments demonstrate successful dispersion of nano-carbon black in cement paste with measurable conductivity and capacitive behavior.
In parallel, we investigate clay gelation, dispersion, and transport in microfluidic domains under varying salinity and pH. We have confirmed the ability to image Laponite at micron scale using phase contrast and fluorescent tagging, enabling 3D reconstruction through z-stacking.
Key Findings
Applying cDFT to model electrolytes at highly charged mineral interfaces (Petersen, 2024), we predicted:
- GPa-scale cohesive stresses between C–S–H grains arising from ion correlations, consistent with AFM and MD studies
- Comparable contributions from out-of-plane and in-plane ion correlations, challenging prior assumptions in the cement physics literature