ASTM E3209/E3209M-20

1.1 This test method covers the equipment, field procedures, and interpretation of the results for the pavement thickness measurements produced by a magnetic pulse induction (MPI) device. Magnetic pulse induction devices induce a weak-pulsed magnetic field that causes the induction of eddy currents in metal objects disturbing the field. In order to measure pavement thickness with an MPI device, a pre-placed metal reflector is required. When the metal reflector enters into the field, an electrical signal is produced and processed through algorithms to detect and produce quantitative values for pavement thickness.

1.2 This test method also provides the details including configuration and metallurgy required to purchase and install reflectors to produce accurate and repeatable results.

1.3 This method is intended for use with plain-jointed concrete pavements, asphalt pavements, base courses with cement binders, and unbound aggregate layers. It is not applicable for continuously reinforced, mesh-reinforced, or fiber-reinforced pavement where the metal reinforcement would interfere with the magnetic field.

1.4 MPI equipment includes a device that induces the magnetic field and collects the electrical signal. The signal information is collected and processed into pavement thicknesses through algorithms programmed into the device firmware.

1.5 MPI field procedures describe the steps and processes required to collect reliable, repeatable, and accurate results from the MPI device. Critical to the accuracy are the metallurgy and configuration of the metal reflectors pre-placed prior to installation of the asphalt or concrete pavement. Also, the absence of any metallic object near the reflector is required to avoid influencing the test result.

1.6 MPI results require little interpretation when the correct reflector calibration is selected and used during the field test.

1.7 Units-The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.