Study on the relation between macro-mechanical properties and micro-structure of geopolymers with different activator...

Area of Science:

• Materials Science
• Geopolymer Chemistry

Background:

• Fly ash-based geopolymer (FABG) containing slag offers field application advantages.
• Activator modulus is a critical parameter influencing FABG properties.

Purpose of the Study:

• To investigate the influence of activator modulus (SiO2/Na2O ratio from 1.1 to 1.5) on FABG properties.
• To explore the mechanism linking activator modulus to macro-mechanical properties and micro-structure.

Main Methods:

• Experimental analysis of FABG properties with varying activator modulus.
• Characterization of micro-structure and reaction products using 29Si NMR.

Main Results:

• Early product is C-A-S-H gel; later stage forms N-(C)-A-S-H gel with higher cross-linking.
• Si/Al ratio in gels decreases with increasing modulus, increasing MCL in C-A-S-H.
• Optimal modulus enhances gel yield, microstructure density, and reduces porosity, increasing strength.

Conclusions:

• Activator modulus critically controls gel formation and microstructure in FABG.
• Gel amount positively correlates with FABG strength development.
• Optimized activator modulus is key for high-performance FABG materials.