PSI - Issue 64

Victor Procópio de Oliveira et al. / Procedia Structural Integrity 64 (2024) 653–660 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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To provide the basis for the comparison suggested in this work, the main conventional methods for measuring and monitoring structural health are listed in Table 1 which presents an overview of various non-destructive testing (NDT) methods commonly used to assess the quality, integrity, and potential defects in concrete structures. Each test method presented in Table 1 offers advantages and limitations in evaluating concrete properties, making them valuable tools in the construction and maintenance of buildings, bridges, and other concrete structures. The tests range from rebound hammer and ultrasonic pulse velocity tests for surface strength and integrity assessment to ground-penetrating radar for mapping buried structures and pathologies. The table also includes the pulsed eddy current test for detecting surface and subsurface defects in conductive materials, along with the half-cell potential test for evaluating the corrosion potential of reinforcements.

Table 1. Summary of conventional SHM testing techniques for concrete structures

Test Type

Description

Numerosity & Position Data Acquisition & Processing

Environmental Influences Surface humidity, ambient temperature, surface type and state, lighting conditions, ventilation, and relative humidity.

References

Rebound Hammer Test

Measures the rebound of a spring-loaded hammer impacting a concrete surface, correlating with surface hardness and compressive strength. Application: Carbonation Resistance Evaluation, Chloride Penetration Evaluation, Repair Adhesion Evaluation, Comparative Materials Studies, Aging and Degradation Monitoring. concrete to assess quality and detect anomalies. Application: Concrete Quality Assessment, Defect and Anomaly Detection, Monitoring Structural Problems, Inspection of Repairs and Reinforcements. Measures the speed of ultrasonic waves through Assesses structural integrity of materials like concrete by detecting internal defects such as delaminations, voids, cracks, and other discontinuities. Application: Inspection of Concrete Structures, Quality Assessment, Monitoring of Existing Structures. Uses high-frequency electromagnetic pulses to investigate subsurface characteristics of materials like soil, rocks, concrete, and asphalt. Application: Detection of pipes, cables, and other buried infrastructure, assessment of concrete pavements and slabs, investigation of foundations and geotechnical characteristics.

Multiple measurements at several representative locations, typically 3-5 measurements per test point. Surface must be clean, and the hammer kept perpendicular to the surface.

Calibration before use, measures rebound distance, recording an R-value. Average rebound values are calculated and converted to compressive strength estimates using manufacturer tables or equations. Records travel time of ultrasonic waves between transducers, considers correction factors for temperature, humidity, and concrete composition. Uses correlation tables and formulas to estimate compressive strength and assess homogeneity by analyzing velocity variations. Records signal picked up by the transducer, converting signals to digital data for analysis. Uses wave propagation speed and time between impact and reflected echo arrival to Manual movement of the antenna along predefined scan lines, maintaining constant movement for quality data. Profiles and images constructed for visualization and interpretation, identifying depth, extent, and characteristics of layers. define depth of discontinuities.

Kumavat, Chandak, Patil (2021), El Mir et al. (2023).

Ultrasonic Pulse Velocity (UPV) Test

Multiple measurements at each test point, generally 3-5 per point. Sending and receiving transducers positioned on opposite, adjacent, or same sides of the material.

Temperature, humidity, freezing and

Lee, Lee (2020), Godinho et al. (2020).

thawing, concrete

composition, age, pressure and voltage, and transducer coupling. Temperature, humidity, surface conditions, environmental noise, and

Impact-Echo Test

Multiple measurements increase the likelihood of detecting defects and verify consistency. Point of impact should be close to the transducer, usually 5 10 cm away. Greater number of scan lines ensures more complete coverage, crucial for large areas. Spacing between scan lines depends on desired spatial resolution and depth of features.

Coleman (2021), Pallarés (2021),

structure geometry variations.

Ground Penetrating Radar (GPR) Test

Humidity, type of structure, climatic conditions, and electromagnetic interferences.

Klewe, Strangfeld, Kruschwitz. (2021). Jiao et al. (2020).