How does GGL compare to CSL?
Like GGL, CSL is a downhole NDE method that is utilized to determine the homogeneity of the concrete within CIDH piles. Instead of using a radioactive source to determine density in a tube, CSL is performed with high-frequency sonic pulses from a pair of probes located in two adjacent tubes. One tube contains a sonic emitter while the second inspection tube contains a receiver. By evaluating the time the sonic signal takes to traverse the distance between probes, the uniformity of the sonic properties of the intervening material can be determined. • While both CSL and GGL determine homogeneity of specific concrete characteristics, they do not give identical results. First, while GGL detects anomalies located around an inspection tube, CSL detects anomalies between pairs of tubes. As such, GGL can see around and outside of the steel reinforcing cage, while CSL examines the concrete deep within the shaft core. As a result, the two tests complement each other, rather than contradict each
