Date of Graduation


Document Type

Problem/Project Report

Degree Type



Statler College of Engineering and Mineral Resources


Civil and Environmental Engineering

Committee Chair

Udaya B. Halabe

Committee Co-Chair

Hota V.S. GangaRao

Committee Member

Hema J. Siriwardane


Aging of civil infrastructures is one of the major problems faced by the engineering industry today, with the concrete structures cracking and the steel reinforcement corroding due to exposure to deicing chemicals, resulting in shorter service life. An alternative to the degrading infrastructures made of concrete and steel is the use of Fiber Reinforced Polymer (FRP) composites, which are noncorrosive. Use of FRP as structural components such as bridge decks and retrofitting jackets can solve the problem of aging with enhanced durability in future constructions. But, proper installation of newer material in structurally important infrastructure requires a reliable method of evaluation or testing. Nondestructive Testing (NDT) or Evaluation (NDE) is a method that can detect the anomalies in the FRP structures keeping the physical properties of the structure intact. Infrared Thermography (IRT) and Digital Tap Testing (DTT) are two extensively used NDT techniques for inspection of infrastructures, because of their portability and easy-to-handle features. This problem report discusses the advanced and conventional IRT and DTT methods to detect subsurface defects in FRP composite bridge components and FRP rehabilitated concrete bridge. Advanced IRT offers high-end infrared camera and robust digital image processing abilities to locate sub-surface defects in the structures, which, in some cases, conventional IRT fails to do. In addition, this report also includes IRT based tests using a low-cost halogen lamp heater, which is compared to the heating capability of VoyageIR Pro (advanced IRT equipment). Also, Digital Tap Hammer was used for rapid evaluation of the defects in the structural members, which provides a scientific alternative to the traditional coin tap method. The extent of applicability of DTT method compared to IRT was studied using several FRP specimens in the laboratory. DTT was limited to defects at lower depth, such as debonds in thin FRP wraps and could not detect delaminations in thick FRP members. The methods were also used in field testing of concrete box beams rehabilitated with carbon FRP fabrics. The field testing enabled the detection of debonds which helped in their immediate repair.