Using Multiple Non-destructive Testing Methods to Assess the Loss of Soil Inside Concrete Embankment

Taiwan is an island surrounded by sea with high mountains, narrow land, and abundant rainfall. Concrete embankments in the coastal areas and river sides are usually constructed to protect people's lives and property. In general, the dikes are composed by a layer of concrete infilled with compacted soil. The base soil might be outflow with time because of water seepage or piping, concrete damage or foundation loss. Dike structure is not suitable for destructive testing methods for assessing its internal situation. Several hundred kilometers of sea and river embankments has been tested by center of NDT for CYUT. In this paper, a variety of non-destructive testing methods are used to detect the loss of soil inside dikes, including Ground Penetrating Radar (GPR), Time of Fight Impact-echo (IE), and normalized IE. Normalized IE is used for verifying substrate condition below concrete shell. Time of Flight IE is used to evaluate whether the surface opening crack is through the thickness of concrete. Proper application of several NDT methods can not only assess the status of the dike but also find the possible cause of the damage.