Description
This paper presents the development and assessment of an optical fiber sensing platform for monitoring chloride concentration and pH range in structural health monitoring of concrete structures. Excessive chloride ions possess the ability to corrode the steels of reinforced concrete structures that affect the safety and health of concrete structures. In addition, the pH of concrete structures decreases to a value close to 9.5 that externally exhibits carbonation and durability problems. Thus, we have constructed an optical fiber sensing platform for monitoring chloride ion concentrations and pH range in concrete structures. The schematic of sensing platform setup for chloride ion concentrations and pH measurement which is composed of a fiber optical sensor with CUV-UV cuvette holder, a broadband light source (200-1100 nm), an UV-NIR spectrometer, and a personal computer for data acquisition. We conducted the sensing platform for monitoring the chloride ion concentrations and pH range of two types of water cement ratios for both fresh concrete and harden concrete materials (w/c = 0.35 and 0.65). We have demonstrated the feasibility of the optical fiber sensing platform for monitoring chloride ion concentrations and pH range in structural health monitoring of concrete structures without modifying optical fiber sensors or coating chemical compounds. The optical fiber sensing platform has shown the capacity for monitoring of chloride ion concentrations in the range from 150 ppm to 12500 ppm as well as pH range from 9 to 13.
