Multifunctional Cement Composites Strain and Damage Sensors Applied on Reinforced Concrete (RC) Structural Elements

Area of Science:

• Materials Science
• Structural Engineering
• Nanotechnology

Background:

• Reinforced concrete (RC) structures require robust monitoring systems.
• Cement composites offer potential as integrated sensing materials.
• Carbon-based nanofillers like nanofibers and fibers can impart electrical properties.

Purpose of the Study:

• To evaluate the strain-sensing and damage-sensing capabilities of carbon nanofiber (CNFCC) and carbon fiber (CFCC) cement composites.
• To compare different sensor configurations (casting, location, contacts) for optimal performance.
• To assess the suitability of these composites as embedded sensors in RC beams.

Main Methods:

• Fabrication and integration of CNFCC and CFCC sensors onto a 4m RC beam.
• Testing under varying casting conditions (in situ, attached), service locations (tension, compression), and electrical contact methods (embedded, superficial).
• Progressive loading to failure to evaluate strain and damage sensing under elastic and ultimate load conditions.

Main Results:

• Both CNFCC and CFCC performed effectively as strain sensors under elastic conditions.
• CNFCC exhibited higher gauge factors (up to 191.8) compared to CFCC (up to 178.9 in tension, 49.5 in compression).
• No distinct damage-sensing mechanism was observed for either composite up to the beam's failure point, although strain sensing persisted.

Conclusions:

• CNFCC and CFCC cement composites are viable for strain monitoring in RC structures, even under severe conditions.
• CNFCC offers enhanced sensitivity for strain detection.
• Further research is needed to develop damage-sensing capabilities for these advanced cementitious sensors.