Standard Practice for Ultrasonic Testing of Geomembranes

Importancia y uso:

5.1 This practice covers test arrangements, measurement techniques, sampling methods, and calculations to be used for nondestructive evaluation of geomembranes using ultrasonic testing.

5.2 Wave velocity may be established for particular geomembranes (for specific polymer type, specific formulation, specific density). Relationships may be established between velocity and both density and tensile properties of geomembranes. An example of the use of ultrasound for determining density of polyethylene is presented in Test Method D4883. Velocity measurements may be used to determine thickness of geomembranes (1, 2).4 Travel time and amplitude of transmitted waves may be used to assess the condition of geomembranes and to identify defects in geomembranes including surface defects (for example, scratches, cuts), inner defects (for example, discontinuities within geomembranes), and defects that penetrate the entire thickness of geomembranes (for example, pinholes) (3, 4). Bonding between geomembrane sheets can be evaluated using travel time, velocity, or impedance measurements for seam assessment (5-10). Examples of the use of ultrasonic testing for determining the integrity of field and factory seams through travel time and velocity measurements (resulting in thickness measurements) are presented in Practices D4437 and D4545, respectively. An ultrasonic testing device is routinely used for evaluating seams in prefabricated bituminous geomembranes in the field (11). Integrity of geomembranes may be monitored in time using ultrasonic measurements.

Note 1: Differences may exist between ultrasonic measurements and measurements made using other methods due to differences in test conditions such as pressure applied and probe dimensions. An example is ultrasonic and mechanical thickness measurements.

5.3 The method is applicable to testing both in the laboratory and in the field for parent material and seams. The test durations are very short as wave transmission through geomembranes occurs within microseconds.

Subcomité:

D35.10

Referida por:

D7700-22, D4437_D4437M-16R23

Volúmen:

04.13

Número ICS:

59.080.70 (Geotextiles)

Palabras clave:

attenuation; geomembrane; mechanical waves; nondestructive; ultrasonic; wave velocity;