" TRB's second Strategic Highway Research Program (SHRP 2) Report S2-R06A-RR-1: Nondestructive Testing to Identify Concrete Bridge Deck Deterioration identifies nondestructive testing technologies for detecting and characterizing common forms of deterioration in concrete bridge decks.The report also documents the validation of promising technologies, and grades and ranks the technologies based on results of the validations.The main product of this project will be an electronic repository for practitioners, known as the NDToolbox, which will provide information regarding recommended technologies for the detection of a particular deterioration. " -- publisher's description.

Corrosion of reinforcing steel bars (rebar) in reinforced concrete decks can lead to serious structural issues in bridges. Ultrasonic Testing (UT) methods provide small wavelengths that can be used for early detection of several types of deterioration. The recently-developed Ultrasonic Guided Wave Leakage (UGWL) Method utilizes steel as the waveguide and measures the energy leaked into the surrounding concrete. Previous studies completed at University of NebraskaLincoln demonstrated that the measurements of the leaked energy using receivers from the concrete surface can successfully identify early stages of various flaws such as corrosion, delamination, and cracking. In this method, the longitudinal waves are generated along the rebar by a transmitter placed directly on the rebar, and recorded by an array of receivers on the concrete surface. Previous studies have shown promise in testing stretches of concrete decks as long as 10 feet using a single transmitter and an array of sensors placed 6 inches apart. The primary goal of this Master's thesis is to demonstrate that the recently developed UGWL method has several advantages over the commonly used Half-Cell Potential (HCP) method in the detection of corrosion in reinforced concrete (RC) bridge decks. To achieve this goal, laboratory experiments as well as a pros-and-cons analysis is conducted. Laboratory specimens are placed in a corrosive environment by submerging them in 10% NaCl solution. These slabs were then monitored for 6 months. During this period, UGWL and half-cell potential data were collected every 6 days. After testing was completed, chloride threshold levels (CTLs) were measured on cores taken from the specimens. The secondary goal of this thesis is to develop a quantitative correlation between UGWL data and CTLs, similar to those established between HCP and CTLs in the literature. The experimental results demonstrated that the UGWL technique detected the corrosion activity approximately 21 days sooner than the HCP method. The findings also suggest that chloride content determined after the completion of the corrosion process, which lasted for 6 months, exceeded the standard chloride threshold levels; confirming that the selected method of inducing corrosion in the lab was successful.

Accurate and timely condition assessment of bridge decks is essential for economic management of aging highway bridges. The ability to evaluate concrete modulus profile in a bridge deck can help the detection of early signs of deterioration and optimize the bridge maintenance procedures. This study presents a new method for modulus profiling of concrete bridge decks. The stiffness matrix method is used to simulate wave propagation in a layered media. The results are compared to numerical finite element models. Dispersion analysis is done using the multi-channel analysis of surface waves (MASW) and phase-shift methods. The characteristics of dispersion surface are analyzed and the effects of model parameters on dispersion surface are examined through a series of parametric studies. An inversion technique is proposed for a fast inversion of surface-wave data collected on bridge decks. This technique utilizes a database of pre-calculated dispersion surfaces and takes advantage of the observed patterns in the parametric study as a priori information for the inversion process.