multiVIEW was retained to evaluate the condition of a concrete bridge deck overlaid with asphalt.
Methodology – bridge deck deterioration
GPR profiles were collected on a set of lines over the bridge deck. Steel reinforcing bar (rebar) perpendicular to the line direction produced a characteristic scattering hyperbola in the GPR cross-section.
The amplitude of the reflected pulse characterized by the scattering hyperbola was measured as an attribute correlated with the degree of deck deterioration (lower amplitudes indicative of higher deterioration).
The reflection amplitude was controlled by the properties of the concrete and rebar (increased attenuation in the concrete related to higher chloride content and/or moisture result in greater signal loss between the surface and rebar resulting in lower amplitudes).
The higher chloride and moisture zones are indicative of probable areas of current or incipient delamination induced by rebar corrosion processes.
Figure 1 shows Location of probable areas of current or incipient delamination.
Table 1 shows the summary statistics including rebar cover thickness.