| Water is one of main factors to deteriorate the reinforced concrete (RC) deck slab of bridge. Surveying moisture distribution of RC slabs using ground-penetrating radar (GPR) becomes an effective way for early detection. we tried to estimate moisture distribution of bridge deck slab using multi-channel GPR with middle range of frequency. The GPR with middle range of frequency can stably detect reflection waves from the bottom face of deck slabs. As the water content inside a deck slab increases, the dielectric constant of the deck slab increases, and the propagation velocity of the electromagnetic wave reflected from the bottom face of the deck slab decreases, which appears on an acquired record as the delay of traveltime of the reflection wave. The distribution of moisture content estimated by analysing GPR records has good relationships with the distribution of moisture content measured directly on the underside of deck slabs, which insists that the GPR can be used to identify the distribution of moisture content inside the deck slab of bridge. |
