Mesoscale texture of cement hydrates

Area of Science:

• Materials Science
• Civil Engineering
• Nanotechnology

Background:

• Cement and concrete properties depend on calcium-silicate-hydrates (C-S-H) formation during hydration.
• Controlling C-S-H structure is challenging due to its complex nature and precipitation mechanisms.
• Recent research highlights the importance of C-S-H mesoscale organization (hundreds of nanometers) over molecular structure for material properties.

Purpose of the Study:

• To unveil the mesoscale texture of C-S-H.
• To connect fundamental nanoscale properties to the macroscale engineering performance of cement and concrete.
• To provide a quantitative understanding of experimental investigations through simulations.

Main Methods:

• Utilized simulations combining nanoscale C-S-H building unit information and effective interactions.
• Employed a statistical physics framework for aggregating nanoparticles.
• Integrated data from atomistic simulations and experimental findings.

Main Results:

• Computed small-angle scattering intensities, pore size distributions, specific surface area, local densities, indentation modulus, and hardness.
• Provided quantitative insights aligning with various experimental investigations.
• Demonstrated how early-stage hydration heterogeneities persist and impact hardened cement paste mechanical performance.

Conclusions:

• Unraveling C-S-H mesoscale texture is crucial for linking material structure to performance.
• Controlling C-S-H mesoscale organization offers a pathway to advanced cementitious material design.
• This research provides a foundation for developing smarter concrete mix designs.