Mechanical properties of cellulose nanocrystal modified cement/fly ash pastes under various water/binder ratios

This study investigates the effect of cellulose nanocrystal (CNC) on the mechanical properties of cement/fly ash pastes under various water/binder ratios through a series of tests, including mechanical test, isothermal calorimetry test, X-ray diffraction test, and mercury intrusion porosimetry test. The results indicate that CNCs have a significant enhancing effect on the mechanical properties of cement/fly ash-cement pastes, with this enhancement being influenced by fly ash and water/binder ratio. CNC has an evident promoting influence on the cumulative heat and heat release rate of cement/fly ash-cement pastes. Higher CNC dosage exhibits a faster hydration reaction in cement pastes with 10 % fly ash. Additionally, with an increase in CNC dosage, there is a rise in the hydration product dosage of cement/fly ash-cement pastes, accompanied by an increase in the proportion of gel pores and transition pores. The study provides insights into potential applications of CNC to enhance the mechanical performance of cement/fly ash-based composites in construction industry. •CNC significantly improve the mechanical properties of cement/fly ash-cement.•Key factors affecting the CNC on the mechanical properties are water/binder ratio and fly ash dosage.•CNC significantly promotes the hydration reactions of cement/fly ash-cement pastes.•Addition of CNC reduces the porosity and increases the proportion of gel and transition pores.