TY - CONF A1 - Trela, Christiane A1 - Kind, Thomas A1 - Günther, Martin T1 - Ground penetrating radar in reflection vs transmission mode for void detection in concrete structures N2 - The concreting of prefabricated concrete structures can lead to insufficient bonding or even to remaining cavities. Honeycombs (aggregate clusters without cement) represent potential weakening of the structure and need to be detected non-destructively. In our study we tested the capability of ground penetrating radar (GPR) techniques for this purpose. We applied GPR in reflection mode and zero-offset profiling (ZOP) transmission mode on a precast concrete twin wall with built-in honeycombs. GPR measurements were performed as two channel measurement with ground coupled antennas with centre frequencies of 1.5 GHz and 2.6 GHz mounted to an automated scanner system. Our findings show that ZOP transmission measurements are a more efficient method to detect voids in reinforced concrete structures compared to reflection mode measurements. This holds for both the effort needed for the measurement and the evaluation as well as the validity of the data. Honeycombs (basically representing voids) are usually characterized by strongly reduced amplitudes and earlier arrivals of the transmitted wave. T2 - International Symposium Non-Destructive Tesing in Civil Engineering (NDT-CE 2015) CY - Berlin, Germany DA - 15.09.2015 KW - Void detection KW - Ground penetrating radar KW - Reflection KW - Transmission KW - Reinforced concrete KW - Prefabricated wall PY - 2015 AN - OPUS4-40005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -