Assessing the Applicability of Lanthanide-Based Upconverting Nanoparticles for Optically Monitoring Cement Hydration...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Lanthanide-based photon upconversion nanoparticles (UCNPs) offer unique optical properties for sensing and barcoding.
• Cement hydration monitoring is crucial for predicting hardened material properties.
• UCNPs are explored as potential reporters for in-situ cement hydration analysis.

Purpose of the Study:

• To evaluate UCNPs for monitoring early cement hydration and as authentication tags for cementitious materials.
• To screen UCNP properties (size, coating, concentration) and cement matrix influences (composition, water-to-cement ratio).
• To determine optimal UCNP application conditions minimizing interference with cement hydration kinetics.

Main Methods:

• Screening of self-made and commercial UCNPs during early cement hydration stages.
• Utilizing reflection and luminescence measurements for online monitoring.
• Complementary analysis using X-ray diffraction (XRD) and isothermal heat-flow calorimetry.

Main Results:

• Identified suitable lanthanide UCNP reporters and application conditions for cement hydration monitoring.
• 25 nm oleate-coated UCNPs at 0.1 wt% showed optimal performance with minimal impact on hydration.
• Higher UCNP concentrations (1.0 wt%) or different coatings/sizes could delay hydration in the initial 24 hours.

Conclusions:

• UCNPs are viable optical reporters for early cement hydration processes.
• UCNPs demonstrate potential as durable optical authentication tags for construction materials.
• Careful selection of UCNP type and concentration is key to avoid negatively impacting cement hydration.