DETECTION OF DELAMINATIONS OF FRP RETROFITTED REINFORCED CONCRETE COLUMNS

by Alan Benjamin Kuper, M.S. Washington State University December 2009 Chair: Mohamed ElGawady The research presented investigates the use of a two probe configuration (transmit and receive) to detect the delamination of fiber reinforcing polymer (FRP) from reinforced concrete (RC). Current methods of detection involve visual inspection and soundings via tapping on the surface with a hammer. These methods are very time consuming, require the presence of an inspector, and possibly additional equipment such as a man lift or ladder. The method under investigation utilizes piezoelectric transducers (PZT), which have the potential to continuously test for delamination and electronically notify when the presence of an inspector is necessary. It was found that commercial probes coupled at an incident angle of 30 degrees and transmitting in the range of 30 kHz to 100 kHz and with a separation of 720 mm were v able to detect a 20 mm delamination located between the probes. This method was also found effective on delaminations of FRP wrapped slabs, FRP wrapped full depth column specimens, and sub-strata delaminations in RC at the depth of the confining steel. The same tests were repeated with PZT wafers adhered to the slab specimen, in place of the coupled commercial probes. The initial results were lacking in the consistency in results that was found using the commercial probes and would require further research.