Nondestructive Evaluation of Installed Soil Nails

Bridge deck condition assessments in Indiana are primarily reliant on visual inspection. The condition of bridge decks, however, is highly dependent on deterioration under the surface, which includes the corrosion of steel reinforcement and concrete delamination. The implementation of reliable nondestructive testing (NDT) methods can provide information about such internal deterioration, but considering the multiple NDT methods currently available, guidance is needed to find the best approach for assessing bridge decks in the state’s bridge inventory. A research program was conducted to examine various NDT methods with the objective of recommending an effective NDT strategy for network-level and project-level bridge inspections in Indiana that will complement information from traditional bridge inspections and provide asset engineers with improved information for long-term programming decisions. For the study, several consultants used various NDT methods to inspect a set of bridge decks that represented a range of desired test variables. Based on the test results, it was determined that aerial infrared thermography (IRT) is a good network-level method that is capable of scanning a large number of bridges and providing an initial assessment of bridge deck conditions. If significant delamination activity is detected, then follow-up network-level scanning limited to the problematic bridge decks should be performed using vehicle-mounted IRT. For project-level scanning of individual bridge decks, impact echo was found to be reliable and repeatable. For bridges with high-traffic volume for which project-level scanning is needed, a pole-mounted IRT system was found to be effective for evaluating the deck condition.

Condition assessment of concrete bridge decks is critical for ensuring structural integrity and public safety, particularly as infrastructure ages. Traditionally, such assessments are made using destructive techniques, such as coring through concrete to collect samples for analysis. However, these invasive methods create weak points within the structure and risk damaging essential components, such as cutting through rebars. This paper explores the use of three non-destructive testing (NDT) methods—electrical resistivity (ER), impact echo (IE), and infrared thermography (IRT)—to evaluate the structural health of concrete bridge decks and overlays. These techniques are tested individually and in combination through a mock-up experiment to detect defects such as delamination and corrosion. The findings demonstrate that while each NDT method has specific strengths—surface ER with a 46.67% detection rate, IE with 40%, and IRT with 53.33%—the combined detection rate increased to 60%. This combined approach provides a more comprehensive assessment and is expected to help establish better maintenance strategies for aging infrastructure. The study highlights the importance of optimizing NDT methods for real-world applications, addressing current limitations such as environmental sensitivity and scanning speed, to improve the early detection and prevention of structural failures.

<div class="section abstract"> <div class="htmlview paragraph">Nondestructive tests are those tests which detect factors related to the serviceability or quality of a part or material without limiting its usefulness. Material defects such as surface cracks, laps, pits, internal inclusions, bursts, shrink, seam, hot tears, and composition analysis can be detected. Sometimes their dimensions and exact location can be determined. Such tests can usually be made rapidly. Processing results such as hardness, case depth, wall thickness, ductility, decarburization, cracks, apparent tensile strength, grain size, and lack of weld penetration or fusion may be detectable and measurable. Service results such as corrosion and fatigue cracking may be detected and measured by nondestructive test methods. In many cases, imperfections can be automatically detected so that parts or materials can be classified.</div> <div class="htmlview paragraph">The SAE Handbook describes the following nondestructive test methods:</div> <ol class="list nostyle"> <li class="list-item"> <div class="htmlview paragraph">SAE J359—Infrared</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J420—Magnetic Particle</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J425—Eddy Current</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J426—Liquid Penetrant</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J427—Penetrating Radiation</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J428—Ultrasonic</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J1242—Acoustic Emission</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J1267—Leakage Testing</div></li></ol> <div class="htmlview paragraph"><span class="xref">Table 1</span> summarizes the principal features of most of these tests. In addition to the tests described, other nondestructive tests exist which are less well established, but whose use is expanding. Among these are microwave tests, holography, and sonic tests. Microwaves are used to locate defects in nonmetallic substances and to determine some physical characteristics of those materials. Optical holography uses coherent light from a laser beam to detect strains and defects in materials by means of three-dimensional imaging and interferometry techniques. Acoustical holography uses ultrasonic waves to image discontinuities in the interior of solids. Recent refinements in sonic testing permit more objective determination of the physical properties of cast iron. Complete information concerning each nondestructive test can be obtained from books listed in the bibliographies of the aforementioned reports.</div> <div class="htmlview paragraph">Increasing consumer demand for product quality at reasonable cost has resulted in development of nondestructive tests which can be applied to materials and manufactured parts. Although a variety of complementary nondestructive methods is available, development time is generally required for application to specific materials or products. The effect of part contour, surface condition, heat treatment, composition variation, and other variables may limit the ability of certain tests to detect imperfections with desired accuracy.</div> <div class="htmlview paragraph">Nondestructive tests properly applied to basic material can add greater assurance of performance to design strengths, thereby affecting material and manufacturing economy. In addition, parts can be tested after each basic operation which is critical to service performance of the finished part. In-process nondestructive tests can also serve as basic components of feedback process control systems since all tests are based upon measurements which do not damage the material or part being inspected.</div></div>

This paper reviews the most common non-destructive testing (NDT) methods of concrete structures as utilized by the structural engineering industry. The fundamentals of NDT methods are explored in regards to their potential, limitations, inspection techniques and interpretations. The factors that influence the success of NDT methods are discussed and ways to mediate their influence are recommended. Reference is made to standard guidelines for the application and interpretation of the discussed NDT methods. NDT of concrete was found to be gaining increasing acceptance as a means of evaluating the strength, uniformity, durability and other properties of existing concrete structures. Perceptions of NDT inadequacy were attributable to lack of understanding construction materials and NDT methods themselves. The intent of this paper is to address these concerns by identifying and describing the most common successful methods of NDT as applied to concrete structures.

Review of NDT methods in the assessment of concrete and masonry structures

Aim of study: Analyze the behavior and predictive capacity of different non-destructive testing (NDT) methods—ultrasound, longitudinal and transverse vibrations, and static bending— for estimating the MOEGTO in two species of great forestry interest in Europe: Pinus sylvestris and Populus × euramericana. Additionally, this study focuses on developing global prediction models for MOEGTO using the NDT modulus of elasticity from both species, and on improving the reliability of prediction through the cross-validation process. Area of study: Provenance Region 8 (Northern Iberian System, Spain) and Ribera del Carrión (Palencia, Spain). Material and methods: A total 75 sawn lumber samples (45 of Pinus sylvestris and 30 of Populus x euramericana) with dimensions of 60 × 40 × 1200 mm were analyzed using ultrasonic testing, longitudinal and transverse vibration methods, and both destructive and non-destructive static bending tests performed with a universal testing machine. Regression models were developed to predict the static modulus of elasticity (MOEGTO). Main results: The prediction model using the NDT method of longitudinal vibrations with Fast Fourier Transform (FFT) software for Pinus sylvestris showed the highest coefficient of determination with R2= 0.56, while for Populus × euramericana, the ultrasound method with the Sylvatest 4 device yielded R2= 0.67. For both species, the best-fit global prediction model was obtained with the ultrasound method using the Sylvatest Trio device, achieving R2= 0.60. Additionally, the application of cross-validation improved the predictive performance of the global models, particularly for the three ultrasound methods and the longitudinal vibration method, all of which attained R2 values above 0.6. Research highlights: This study confirms the reliability of ultrasound and longitudinal vibration techniques for estimating MOEGTO and contributes new insights by comparing multiple NDT methods across two species and developing robust cross-validated global prediction models.

Condition assessment and characterization of materials and structures by means of nondestructive testing (NDT) methods is a priority need around the world to meet the challenges associated with the durability, maintenance, rehabilitation, retrofitting, renewal and health monitoring of new and existing infrastructures including historic monuments. Numerous NDT methods that make use of certain components of the electromagnetic and acoustic spectrum are currently in use to this effect with various levels of success and there is an intensive worldwide research effort aimed at improving the existing methods and developing new ones. The knowledge and information compiled in this book captures the current state of the art in NDT methods and their application to civil and other engineering materials and structures. Critical reviews and advanced interdisciplinary discussions by world-renowned researchers point to the capabilities and limitations of the currently used NDT methods and shed light on current and future research directions to overcome the challenges in their development and practical use. In this respect, the contents of this book will equally benefit practicing engineers and researchers who take part in characterization, assessment and health monitoring of materials and structures.

The long-term effects of scour have been identified as one of the primary reasons for bridge failure. To evaluate the performance of the bridges against scour, it is essential to assess the conditions of the bridge foundation including the depth of the piles. Sonic Echo (SE) has been a favorable nondestructive method to evaluate the condition of unknown bridge foundations in the recent decades. Previous studies have shown that the results obtained from SE tests can be affected by a variety of factors such as the pile-to-soil stiffness ratio, length-to-diameter ratio of the pile, presence of defects and anomalies near the pile head, striking method, and hammer type. Although previous studies have discussed such affecting factors, there is a lack of comprehensive investigation regarding the effect of striking method and hammer tip type specific to wood piles supporting bridge decks. In the current study, the effect of striking method and hammer type on the success of SE tests conducted on wood piles has been scrutinized by investigating various options of striking methods and hammer tip types. After comparing different options, superior ones were identified and recommendations for better conducting the SE tests on unknown wood bridge foundations were presented. Numerical simulations were also performed to support some of the conclusions.

Several industries use non-destructive testing (NDT) methods to check the properties of parts and structures for flaws and oddities without affecting the part's stability or causing damage to the part being checked. It involves surveillance. Situation of the materials (Material State Awareness (MSA)) and the structural health monitoring (SHM). Using NDT procedures can help eliminate potential losses and risks associated with component failures while reducing both money and time by not sacrificing its reliability and upcoming utilization. On the other hand, machine learning (ML) and artificial intelligence (AI) techniques are practical instruments that can aid in automated data collection and analysis, offering fresh insights and perhaps enhancing detection efficiency at a high cost quickly and easily. The present research provides an overview of modern AI-ML NDT algorithms and their applications of associated with smart technologies, such as digital twins and machine vision (MV).

Buildings constructed during early 70's & late 80's of the last century in India are found to be in distressed conditions due to inadequate specifications and poor construction practices. The continuous monitoring of concrete structures using suitable NDT (Non Destructive Testing) methods and use of possible restoration methods help in a considerable reduction of the rate of deterioration of concrete structures thereby increasing the life span of structures. NDT methods have greater advantage in evaluating the uniformity, homogeneity, approximate compressive strength, durability, the extent of corrosion of rebars in concrete etc. of damaged structures. The objective of the present study is to enhance the life of 50 year old existing hospital building (Partly RC and Brick masonry) in Kurnool, Andhra Pradesh. Condition assessments are carried out through a visual, field and laboratory evaluation of samples collected from the structure and results are presented in this paper. The paper also highlights the assessment of strength and durability of concrete to evaluate the extent of distress and damage in the building. Besides visual inspection, the Non Destructive Evaluation covering UPV & Rebound Hammer values and Half Cell Potential with respect to the status of corrosion of reinforcing bars and chemical tests on selected un-distressed RC columns, beams, and slabs are also presented and discussed. The repair and strengthening techniques using the latest materials and possible restoration works such as column jacketing, shotcreting, anticorrosive coatings, etc. have been suggested to enhance the life of the structure.

Assessing the load carrying capacity of concrete anchor bolts using non-destructive tests and artificial multilayer neural network

Sufficient bonding between the hot mix asphalt (HMA) layers is essential to ensure the desired structural capacity of a pavement. Undetected delamination can ultimately result in the peeling of thin overlays of asphalt concrete from the surface of the roadway. Further progression of delamination may result in stripping of the lower layers due to the intrusion of moisture. Rapid nondestructive test (NDT) methods determine the existence and extent of delamination or stripping within the asphalt pavements. In this paper, several NDT procedures and/or equipment that have the potential to address the problem were identified, and their effectiveness and potential for success were evaluated. The identified NDT methods, which included the Ground Penetrating Radar, Thermography, sonic/seismic and impulse response, were evaluated on a controlled pavement section that was specifically constructed with various levels of debonding at different depths and with different asphalt mixes. Strengths and limitations of different methods are discussed in this paper.

Corrosion of reinforcement can decrease the quality and cause damage to reinforced concrete, so it is necessary to know the resistance of concrete, especially with oil palm shells (OPS) and mask fibers in a corrosive environment. This study aims to determine the effect of corrosion levels on OPS concrete and mask fiber using the NDT (non-destructive testing) method. Oil palm shells are a 10% replacement for coarse aggregate in the concrete mix. The mask fiber is 0.2% of the volume of the specimen, and the superplasticizer is 0.25% of the cement used as an additive in the concrete mixture. The specimen is 50 cm long, 10 cm wide, and 10 cm high. There are two types of specimens, namely pre-corrosion and post-corrosion. In pre-corrosion specimens, corrosion acceleration of the reinforcement is carried out before the concrete molding process. While the post-corrosion specimen is being prepared, corrosion acceleration is carried out after the concrete is 28 days old. Corrosion acceleration is carried out by immersing the concrete specimen in a 5% NaCl solution and using a DC power supply. After the concrete is corroded, NDT is carried out. The NDT methods used are resistivity and impact-echo as analysis and detection tools for the effect of corrosion on palm shell concrete and mask fiber. The pre-corrosion specimen got the highest resistivity value on the 0% specimen at 21.35 kΩ.cm and the lowest resistivity on the 5% specimen at 16.70 kΩ.cm. The resistivity value decreases with increasing corrosion levels. The post-corrosion concrete has the highest resistivity on the 0% specimen, with 18.56 kΩ.cm, and the lowest resistivity on the 5% specimen, with 13.88 kΩ.cm. The resistivity value decreases with increased corrosion levels. The impact-echo testing on the pre-corrosion specimen yielded a 0% specimen with a value of 14394.53 Hz and a 1% specimen of 18266.6 Hz. The frequency value decreases with increasing corrosion levels. The result of impact-echo testing on post-corrosion concrete was 14394.53 Hz for the 0% specimen and 1567.38 Hz for the 5% specimen. The frequency value decreases with increasing corrosion levels.

Asphalt pavement density measurement using non-destructive testing methods: current practices, challenges, and future vision

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