Abstract

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be designed to satisfy the specific demand for an economic way to monitor concrete infrastructure health. For this purpose, we embedded a thin magnetic microwire in the core of a cement-based cylinder, which was inserted into the concrete specimen under study as an extra aggregate. The experimental results show that the embedded MMCC sensor is capable of measuring internal compressive stress around the range of 1–30 MPa. Two stress sensing properties of the embedded sensor under uniaxial compression were studied: the peak amplitude and peak position of magnetic switching field. The sensitivity values for the amplitude and position within the measured range were 5 mV/MPa and 2.5 μs/MPa, respectively.

Highlights

  • The extensive application of concrete structures in recent years has made the observation, monitoring, and evaluation of their structural condition in real time to minimise in-depth inspections or any kind of major accidents a very important matter

  • The values of compressive strength obtained in mortar and concrete specimens without sensor were

  • The compressive stress measured by the microwire embedded in cement-based composite (MMCC) sensor was calculated based on the change in the properties of this sharp voltage peak induced in the pick-up coil

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Summary

Introduction

The extensive application of concrete structures in recent years has made the observation, monitoring, and evaluation of their structural condition in real time to minimise in-depth inspections or any kind of major accidents a very important matter. The dynamics of domain wall propagation can be very effectively modified by the different anisotropies introduced into the microwire by a magnetic field [20], mechanical stress [21], thermal treatment [22], etc Due to their complex anisotropy distribution, microwires have very fast domain wall propagation with the domain wall velocities of up to 18,000 km/s [12], which gives us an opportunity to obtain induced signals even from a small volume of single microwires. The domain wall dynamics in glass-coated microwires is strongly dependent on external parameters, such as magnetic field, temperature, mechanical stress, and so on [16]. Such variations increase the application potential of the microwire. The smart concrete aggregate is a cement-based stress/strain sensor which has been developed by utilizing the stress/strain sensing property of an embedded magnetic microwire in cement-based composite (MMCC)

Fabrication
Bistability and Design of MMCC Sensors
Mechanical Behaviour of Concrete and Mortar Specimens
Compressive Stress Sensing Property of MMCC Sensor
Compressive Stress Sensing Properties of Embedded MMCC Sensor
Conclusions
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