Temperature Sensing and Hydration Study of Carbon Nanofiber Aggregates

Abstract

Fiber research in concrete construction technology has been helping to prevent catastrophic disasters due to the loss of structural integrity and service life by functioning as structural health monitoring (SHM) technology. Past studies demonstrated the use of self-consolidating carbon nanofiber concrete (SCCNFC) as a structural sensor, which led to the development of carbon nanofiber aggregates (CNFAs) to be used as strain sensors to determine localized strains in concrete structures. This paper examines the effect of temperature and hydration on CNFAs. In the temperature study, the specimens containing CNFA were monitored for temperature sensing capability through one complete cooling and heating cycle (−20°C to 90°C), giving the mathematical model to predict the thermal behavior of CNFAs used to monitor the temperature of embedded structures. In the hydration study of CNFAs, this paper critically examines the effect of water on the electrical resistance of CNFAs and demonstrates the necessity of the waterproof coating in embedded CNFAs for reliable SHM.