# Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures

Research output: Contribution to journalArticle

6 Citations (Scopus)

### Abstract

In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mepsilon of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mepsilon compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10−2 and −2 × 10−4 respectively. The typical strain resolution in the uniaxial sensor was 100 $\mu \varepsilon$. The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mepsilon of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10−2 and 4 × 10−5 respectively. The biaxial sensor's strain resolution was approximately 10 $\mu \varepsilon$ in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.
Language English 045011 8 Smart Materials and Structures 24 4 10.1088/0964-1726/24/4/045011 Published - 24 Feb 2015

### Fingerprint

Geopolymers
concrete structures
structural health monitoring
Structural health monitoring
Hybrid sensors
Concrete construction
Optical fibers
optical fibers
sensors
Sensors
Wavelength
Curing
axial strain
curing
Acoustic impedance
wavelengths
Fiber Bragg gratings
Temperature
impedance
metal fibers

### Keywords

• remote sensing
• geopolymer sensors
• health monitoring

### Cite this

@article{3b1274b2b679447eba99a444bb4d6204,
title = "Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures",
abstract = "In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mepsilon of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mepsilon compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10−2 and −2 × 10−4 respectively. The typical strain resolution in the uniaxial sensor was 100 $\mu \varepsilon$. The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mepsilon of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10−2 and 4 × 10−5 respectively. The biaxial sensor's strain resolution was approximately 10 $\mu \varepsilon$ in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.",
keywords = "remote sensing, geopolymer sensors, health monitoring",
author = "M Perry and M Saafi and G Fusiek and P Niewczas",
year = "2015",
month = "2",
day = "24",
doi = "10.1088/0964-1726/24/4/045011",
language = "English",
volume = "24",
journal = "Smart Materials and Structures",
issn = "0964-1726",
number = "4",

}

In: Smart Materials and Structures, Vol. 24, No. 4, 045011, 24.02.2015.

Research output: Contribution to journalArticle

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T1 - Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures

AU - Perry, M

AU - Saafi, M

AU - Fusiek, G

AU - Niewczas, P

PY - 2015/2/24

Y1 - 2015/2/24

N2 - In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mepsilon of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mepsilon compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10−2 and −2 × 10−4 respectively. The typical strain resolution in the uniaxial sensor was 100 $\mu \varepsilon$. The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mepsilon of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10−2 and 4 × 10−5 respectively. The biaxial sensor's strain resolution was approximately 10 $\mu \varepsilon$ in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.

AB - In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mepsilon of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mepsilon compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10−2 and −2 × 10−4 respectively. The typical strain resolution in the uniaxial sensor was 100 $\mu \varepsilon$. The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mepsilon of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10−2 and 4 × 10−5 respectively. The biaxial sensor's strain resolution was approximately 10 $\mu \varepsilon$ in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.

KW - remote sensing

KW - geopolymer sensors

KW - health monitoring

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