Spatially resolved capacitance-based stress self-sensing in concrete

Area of Science:

• Civil Engineering
• Materials Science
• Structural Health Monitoring

Background:

• Structural health monitoring (SHM) is crucial for infrastructure maintenance.
• Developing cost-effective and non-intrusive sensing methods for concrete structures is an ongoing challenge.
• Capacitance-based sensing offers potential for embedded or surface-attached monitoring systems.

Purpose of the Study:

• To demonstrate spatially resolved stress self-sensing in unmodified concrete using capacitance measurements.
• To investigate the relationship between applied stress, spatial resolution, and capacitance changes.
• To evaluate the feasibility of this method for practical structural health monitoring applications.

Main Methods:

• Utilized parallel coplanar aluminum electrodes attached to concrete surfaces.
• Measured in-plane capacitance changes in response to applied compressive loads.
• Varied loading conditions and electrode configurations to assess spatial resolution and sensitivity.

Main Results:

• Achieved spatial resolution of 45 mm in the direction of capacitance measurement.
• Demonstrated monotonic and reversible decrease in capacitance with increasing compressive stress (up to 3000 Pa).
• Observed higher fractional capacitance decrease for more concentrated loading and smaller inter-electrode distances.

Conclusions:

• Spatially resolved capacitance-based stress self-sensing is feasible in unmodified concrete.
• The method is sensitive to load concentration and inter-electrode distance.
• Embedded steel reinforcement with a 20 mm concrete cover did not interfere with the sensing capability.