An embedded stress sensor for concrete SHM based on amorphous ferromagnetic microwires

Area of Science:

• Civil Engineering
• Materials Science
• Sensor Technology

Background:

• Critical civil infrastructure requires robust structural health monitoring (SHM).
• Existing monitoring methods can be costly or lack precision.
• Smart aggregate sensors offer a promising alternative for embedded structural assessment.

Purpose of the Study:

• To propose and evaluate a new smart concrete aggregate design for SHM.
• To develop a cement-based stress/strain sensor utilizing magnetic microwire.
• To assess the sensor's capability for economic monitoring of concrete infrastructure health.

Main Methods:

• A magnetic microwire was embedded in a cement-based composite (MMCC) cylinder.
• The MMCC cylinder was integrated into concrete specimens as a smart aggregate.
• The sensor's response to uniaxial compression was measured by monitoring magnetic property variations.
• Two stress sensing properties (peak amplitude and peak position of magnetic switching field) were analyzed.

Main Results:

• The embedded MMCC sensor successfully measured internal compressive stress in the range of 1-30 MPa.
• The sensor demonstrated sensitivity values of 5 mV/MPa for peak amplitude and 2.5 µs/MPa for peak position.
• The contact-less sensing mechanism relies on magnetic property variations due to stress.

Conclusions:

• The developed magnetic microwire embedded in cement-based composite (MMCC) aggregate is a viable candidate for SHM applications.
• This smart aggregate provides an economic and effective method for monitoring the health of concrete structures.
• The sensor's ability to measure stress non-destructively opens new avenues for infrastructure maintenance.