| The aim of this study was to establish a method for monitoring concrete neutralization by using an appropriate fiber optic sensor. As the first step, we developed a novel fiber optic sensor to detect the decrease in pH of pore liquid within the concrete. The proposed sensor was prepared by incorporating poly(N-vinylacetamide) gel containing a pH indicator into a slit in a plastic optical fiber. In order to confirm the practicality of the sensor, monitoring experiments were carried out using a piece of mortar in which the sensor was embedded. Each end of the optical fiber was connected to a tungsten halogen light source and the detector of a visible spectrometer, respectively. The visible spectrum of light transmitted through the optical fiber was monitored during immersion of the mortar in HCl solution. The results suggest that our sensor can be used to detect the pH decrease in concrete caused by CO2. |
