 The TDR test requires minimal of preparation and is able to find defects corresponding to cracks, reductions in section and zones of poor quality concrete

The test is based on wave propagation theory.The name "low-strain dynamic test" stems from the fact that when a light impact is applied to a pile it produces a low strain.The impact produces a compression wave that travels down the pile at a constant wave speed (similarly to what happens in high strain dynamic testing).