Gamma-Gamma Logging (GGL)

ACS offers Gamma-Gamma logging, (GGL) services for clients and has over 20 years of experience with the method. Our company has performed GGL testing on some of the largest projects in the state, from the new California High Speed Rail, to the Bay Bridge in San Francisco, to the new metro in Los Angeles. Our team of qualified and certified engineers combines punctual and efficient testing services with rapid report turnaround. We are happy to answer any questions you may have about the Gamma-Gamma logging method, as well as to provide recommendations for testing services based on your unique project needs.


Gamma-Gamma logging is a non-destructive test performed on CIDH piles or concrete walls that uses a nuclear density probe to create a log of average bulk density vs. pile depth.  Deviations in average bulk density are used to identify pile anomalies or defects and to assess pile/concrete quality.

The testing procedure utilizes an electric winch to pull a 4-foot probe with the radioactive source at the end, up through PVC pipes installed in the concrete. As the probe moves up through the tubes, it reads average concrete densities at set intervals. These intervals then be later plotted and analyzed.

ACS, Inc. performs Gamma-Gamma Logging according to the CalTrans CT-233 test standard. This standard is the most recognized specification for GGL testing throughout the state of California and beyond.

For a PDF version of the Sample Density vs. Depth GGL Plot, click here.

For ACS’s information brochure about GGL, please click here.