Performance study of Portland cement grouting materials enhanced with nanobubbles

This study investigates the use of nanobubbles as an innovative additive to enhance Portland cement grouts in geotechnical engineering. Unlike conventional nanomaterials that tend to aggregate, nanobubbles are rapidly generated and remain stably dispersed due to electrostatic repulsion. Systematic experiments with varying water-cement ratios were conducted to evaluate their effects on key cement grouting performance parameters. Results indicate that nanobubbles reduce internal friction within the cement slurry by acting as lubricants between cement particles, improving flowability by 7.5 % and enhancing rheological properties. Their surface electronegativity facilitates uniform particle dispersion, thereby increasing slurry stability. Furthermore, XRD and SEM analyses reveal that nanobubbles accelerate hydration kinetics by providing abundant nucleation sites, promoting calcium hydroxide (CH) formation, and refining the microstructure. This densification leads to a 4.8 %–24.1 % increase in 28-day compressive strength. The findings demonstrate a scalable and sustainable approach for high-performance cement grouts, advancing nanotechnology applications in construction. • The performance of cement grouting materials enhanced with nanobubbles is investigated. • Comparative analysis of two cement grouting materials is conducted. • The mechanisms for optimizing setting time and mechanical properties are analyzed. • The nanobubble Portland cement grouting material is proposed.