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Smart Structures and Systems
  Volume 12, Number 1, July 2013, pages 41-54
DOI: http://dx.doi.org/10.12989/sss.2013.12.1.041
 


A novel Fabry-Perot fiber optic temperature sensor for early age hydration heat study in Portland cement concrete
Xiaotian Zou, Alice Chao, Nan Wu, Ye Tian, Tzu-Yang Yu and Xingwei Wang

 
Abstract
    Concrete is known as a heterogeneous product which is composed of complex chemical composition and reaction. The development of concrete thermal effect during early age is critical on its future structural health and long term durability. When cement is mixed with water, the exothermic chemical reaction generates hydration heat, which raises the temperature within the concrete. Consequently, cracking may occur if the concrete temperature rises too high or if there is a large temperature difference between the interior and the exterior of concrete structures during early age hydration. This paper describes the contribution of novel Fabry-Perot (FP) fiber optic temperature sensors to investigate the thermal effects of concrete hydration process. Concrete specimens were manufactured under various water-to-cement (w/c) ratios from 0.40 to 0.60. During the first 24 hours of concreting, two FP fiber optic temperature sensors were inserted into concrete specimens with the protection of copper tubing to monitor the surface and core temperature change. The experimental results revealed effects of w/c ratios on surface and core temperature developments during early age hydration, as well as demonstrating that FP fiber optic sensors are capable of capturing temperature variation in the concrete with reliable performance. Temperature profiles are used for calculating the apparent activation energy (Ea) and the heat of hydration (H(t)) of concrete, which can help us to better understand cement hydration.
 
Key Words
    structural health monitoring; concrete hydration; water-to-cement ratio; fiber optic temperature sensor; Fabry-Perot
 
Address
Xiaotian Zou and Xingwei Wang : Department of Biomedical Engineering and Biotechnology, University of Massachusetts,
Lowell, Massachusetts 01854-2827, USA
Alice Chao and Tzu-Yang Yu : Department of Civil and Environmental Engineering, University of Massachusetts,
Lowell, Massachusetts 01854-2827, USA
Nan Wu, Ye Tian and Xingwei Wang : Department of Electrical and Computer Engineering, University of Massachusetts, Lowell, Massachusetts 01854-2827, USA
 

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