Case study of radar laboratory work on the masonry arch bridge

The objective of this case study was to undertake a variety of radar tests on a laboratory controlled masonry arch bridge. This bridge consisted of arch barrels formed of engineering bricks faced by timber retaining walls. The fill of the structure was sharp sand. Radar antennae of 500MHz, 900MHz and 1.5GHz were used for the tests to choose the optimum antenna to identify the change in moisture content, with the radar dragged along the surface of the sand. Three amounts of water were added to the arch structure over the left hand side arch. All three radar antenna frequencies were able to identify the increase in the dielectric constant of the sand caused by the addition of the water. Attenuation of the radar wave and the dielectric constant increased as the moisture content decreased. The best image was produced by the 1.5GHz antenna. For the covering abstract see ITRD E122906.