Basic principles of non-destructive testing .
(1) Most non-destructive testing methods are: The test is based on the evaluation of the results of various properties measurements. that is related to the properties of the structure or associated with different deterioration mechanisms, which are predominantly indirect assessment methods. The heart of nondestructive testing is to collect sufficient structural health assessment data without causing significant damage to the structure. damage to the structure in too much level Some non-destructive inspection methods may require drilling small holes in the concrete structure or may cause some degree of damage to the concrete structure.
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(2) Inspection by non-destructive testing techniques can be applied in the following cases:
2.1. Quality inspection of new construction works
2.2. Solving construction problems during construction
2.3. Examining the condition of old structures for maintenance planning
2.4. Quality assessment of repair work
(3) The selection of the appropriate non-destructive testing method depends on the structural properties data to be inspected, where Table 1 lists the non-destructive testing methods for concrete structures. including an examination according to the reference standards of the Department of Public Works
List of non-destructive testing methods
- Inspection of reinforced concrete structures steel by visual inspection
– Assess the cause and the degree of damage or deterioration that occurs in the structure
- Method for determining the strength of concrete with a rebound hammer
– assess the compressive strength of concrete
- Test method for evaluating concrete compressive strength by firing with a test probe (Penetration Resistance)
– assess the compressive strength of concrete
- Method for testing concrete using ultrasonic waves (Ultrasonic Pulse Velocity)
– Check the stability of concrete quality in the structure or find gaps in concrete structure
- Method for checking the position of reinforcement in concrete (Cover Meter)
– Detect the position of the reinforcement in the structure and measure the distance of the steel clad concrete.
- Test method for corrosion of reinforcing steel (Half-Cell Potential Test)
– Assess the chance of rusting in reinforcing steel
- Test methods for assessing health of concrete with hertube radar waves
– Check for gaps or foreign objects in concrete structure
In addition to the aforementioned non-destructive testing methods There are also a number of other non-destructive testing methods, such as
- Fundamental Frequencies are measured with the objective of identifying changes in The aerodynamic significance of the following properties is modulus of elasticity. Rigid modulus and Poisson ratio The principle of testing is that the sample is vibrated at different frequencies. which the highest point at The apparent response is the fundamental frequency.
- Nuclear Gamma Radiation is used to determine the density of concrete in place by taking a source of gamma rays. Alternatively, the probe is mounted in a probe, which is inserted into the concrete hole of known depth. to compare The density of concrete from the comparison chart (Calibration)
- Resonant Frequency Testing The objective is to find fundamental modes (Fundamental Modes) in the laboratory of vibration for aerodynamic calculations. Used in the field for detecting gaps, stratification, impurity, deterioration. And using the basic principle is that the state of resonant frequency (Resonant Frequency) will be caused between two reflecting surfaces, energy will be put into the system. by using a hammer blow or using an oscillator amplifier system.
