Microwave NDE of RC Beams Strengthened with CFRP Laminates Containing Surface Defects and Tested under Cyclic Loading


Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, the presence of defects in the form of delaminations between the CFRP laminate and concrete substrate may significantly affect the structural integrity and stiffness of the structural section. Microwave near-field nondestructive evaluation (NDE) techniques, utilizing open-ended rectangular waveguides, have the ability to detect these defects. This paper presents the results of an investigation on the influence of cyclic loading on delaminations in reinforced concrete beams fabricated and strengthened with CFRP laminates. The delaminations were formed in the beams by applying pressured air beneath CFRP sheets when epoxy was in fresh state. The beams were exposed to severe environmental conditionings and sustained load of 40% of the ultimate moment capacity. All the beams were cycled under fatigue loading for 2- million cycles. A microwave reflectometer and an automated scanner were used in order to study the behaviour of the delaminations under cyclic loading.

Meeting Name

16th WCNDT 2004 - World Conference on NDT (2003: Aug. 30-Sep. 3, Montreal, Canada)


Civil, Architectural and Environmental Engineering

Second Department

Electrical and Computer Engineering


University of Missouri--Rolla. Applied Microwave Nondestructive Testing Laboratory
United States. Federal Highway Administration
University of Missouri--Rolla. Repair of Buildings and Bridges with Composites Cooperative Research Center
University of Missouri--Rolla. University Transportation Center Program

Keywords and Phrases

Carbon Fiber Reinforced Polymer (CFRP) Laminates; Cyclic Loading; Delaminations; Stiffness; Structural Integrity; Reflectometer; Reinforced concrete

Document Type

Article - Conference proceedings

Document Version


File Type





© 2004 NDT (non destructive testing) c/o Bongiovanni Research & Technology, Inc., All rights reserved.

Publication Date

01 Sep 2004