Connecting to Concrete: Wireless Monitoring of Chloride ions in Concrete structures. (2015)

• Record Type: Journal Article
• Authors: Abbas, Yawar; ten Have, Bas; Hoekstra, Gerrit I.; Douma, Arjan; de Bruijn, Douwe; Olthuis, Wouter; van den Berg, Albert
• Is Part Of: Procedia engineering. Volume 120(2015)
• Page Start: 965
• Page End: 968
• Publication Date: 2015
• Subjects: Passive wireless monitoring -- electromagnetic coupling -- resonance frequency -- chloride ions -- concrete structure -- potentiometry; Engineering -- Congresses; Engineering -- Periodicals; Engineering; Conference proceedings; Periodicals; 620.005
• DOI: 10.1016/j.proeng.2015.08.827
• Languages: English
• ISSNs: 1877-7058

Abstract

Abstract: For the first time, chloride ions are measured wirelessly in concrete. The half-cell potential of a silver/silver chloride (Ag/AgCl) electrode, which corresponds to the concentration of chloride ions, is measured wirelessly. Wireless communication is achieved by an inductive coupling (reflected-impedance) between the coils of the sensor and the readout. The resonance frequency of the sensor coil changes due to the change in the capacitance of a varactor element connected to the Ag/AgCl electrode. The capacitance of the varactor increases with the increase inchloride ion concentration (20 pF/decade). Furthermore, the capacitance can be reliability measured up to a distance of 35 mm between sensor and readout coil. No battery is needed to power the sensor terminal, which makes it feasible to embed it in concrete structures.