Evaluation of the Depth of Deteriorations in Concrete Bridge Decks with Asphalt Overlays Using Air-Coupled GPR: A Case Study from a Pilot Bridge on Korean Expressway

International Journal of Concrete Structures and Materials

Table 6 Dual-criteria based GPR interpretation for condition assessment of concrete bridge decks with asphalt overlays in Korea expressway networks.

Category	GPR		Assessment and analysis
Category	Relative permittivity	Depth-corrected attenuation (dB)	Waterproof function	Deteriorated environment	Concrete deterioration	Rebar corrosion
Good	ε < 11	δ < 5	Good	×	×	×
Fair	ε ≥ 11	δ < 5	Poor	×	×	×
Poor	ε ≥ 11	9 > δ ≥ 5	Good	○	○	×
Serious	ε ≥ 11	δ ≥ 9	Poor	○	○	○
Watch	ε < 11	δ ≥ 5	Good	○	○	∆