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Elastic and Electronic Properties of Alkali Charge-Balanced Calcium Aluminosilicate Hydrate Nanocomposites: A
Klara Schönfeld1, Mohammadreza Izadifar1, Neven Ukrainczyk1
1Institute of Construction and Building Materials, Technical University of Darmstadt, Franziska-Braun-Str. 3, 64287 Darmstadt, Germany.
ACS Omega
|July 3, 2026
Summary
This study used density functional theory to analyze alkali-activated cement nanocomposites reinforced with functionalized reduced graphene oxide (rGO). Hydroxyl-functionalized rGO significantly improved mechanical properties, especially in sodium-based systems.
Area of Science:
- Materials Science
- Nanotechnology
- Computational Chemistry
Background:
- Graphene-based nanomaterials offer superior elastic properties for cementitious nanocomposites.
- Alkali-activated slag (AAS)-derived gels, like C-A-S-H, are promising sustainable binders.
- Understanding the interfacial behavior of functionalized graphene in these systems is crucial for performance enhancement.
Purpose of the Study:
- To investigate the electronic and elastic properties of alkali-activated Al-substituted tobermorite (C-A-S-H) gels reinforced with hydroxyl- and epoxy-functionalized reduced graphene oxide (rGO).
- To analyze the influence of rGO functionalization and alkali type (Na vs. K) on the structural integrity and mechanical performance of these nanocomposites.
Main Methods:
- Density Functional Theory (DFT) simulations were employed to model and analyze the behavior of C-(Na)-A-S-H and C-(K)-A-S-H gels with functionalized rGO.
- Electronic structure and elastic properties, including Young's and bulk moduli, were calculated.
Main Results:
- Hydroxyl-functionalized rGO demonstrated superior reinforcement compared to epoxy-functionalized rGO, primarily through strong covalent bonding.
- Na-based nanocomposites exhibited greater improvements in elastic properties and ionic interactions than K-based counterparts.
- Significant enhancements in Young's modulus (up to ~74%) and bulk modulus (up to ~96%) were observed with rGO functionalization.
Conclusions:
- Both hydroxyl- and epoxy-functionalized rGO effectively reinforce alkali-activated slag-derived gels.
- Hydroxyl-functionalization leads to enhanced proton mobility and stabilization via covalent bonds.
- The choice of alkali (Na vs. K) and rGO functionalization type critically impacts the mechanical performance of cementitious nanocomposites.
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