Detecting moisture distribution in concrete slabs using ground-penetrating radar
Abstract
Early detection of erosion damage in reinforced concrete slabs is required to reduce collapse of the bridge deck. We developed the method using ground-penetrating radar (GPR) to detect the area of moisture retention in deck slabs, which is one of main causes to make erosion of concrete. GPR tool is sometimes used to detect water content in soil and its electromagnetic signals have high sensitivity to moisture content in porous medium. We used multichannel GPR with 4 transmitters and 9 receivers. Intervals of survey lines are 65 mm and trace intervals are 1.8 mm. The central frequency is about 900 MHz, which is analyzed from recorded signals. The equipment has GNSS technology to decide survey locations. The deteriorated area of deck slabs can be identified with abnormal signals of GPR equipment, but the signals acquired through simple analysis cannot classify deteriorated areas and repaired areas. We confirmed techniques and performance of GPR to survey bridge decks using a test slab, for example, to use the amplitude change of diffraction waves from reinforcing steels influenced by the moisture retention. We also indicated causes to change the propagation of electromagnetic waves traveling through a deck slab using results examined with the test slab and proposed to some ways to detect the area with high water content. Finally, we found that the GPR data acquired at different travel times or with different attributes can be applied to detect the deterioration on the upper surface and the water leakage on the lower face of concrete slabs.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMNS35C0374O