1、Standard Method of Test for Pavement Thickness by Magnetic Pulse Induction AASHTO Designation: T 359M/T 359-181 Technical Section: 3c, Hardened Concrete Release: Group 1 (April) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.
2、C. 20001 TS-3c T 359M/T 359-1 AASHTO Standard Method of Test for Pavement Thickness by Magnetic Pulse Induction AASHTO Designation: T 359M/T 359-181Technical Section: 3c, Hardened Concrete Release: Group 1 (April) 1. SCOPE 1.1. This test method covers the determination of the pavement thickness by u
3、sing magnetic pulse induction. 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 rein
4、forcement would interfere with the magnetic field. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish app
5、ropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: T 148, Measuring Length of Drilled Concrete Cores 2.2. ASTM Standard: C802, Standard Practice for Conducting an Interlaboratory Test Program to D
6、etermine the Precision of Test Methods for Construction Materials 3. SUMMARY OF TEST METHOD 3.1. The method uses magnetic pulse induction technology to measure the thickness of one or several layers above a metal reflector. While scanning, the device generates a variant magnetic field that creates a
7、n eddy current in the reflector. The eddy current will generate an induced magnetic field inside the reflector, the intensity of which is detected by sensors from the device. For a given type of reflector, the intensity of the induced magnetic field is determined primarily by the distance from the d
8、evice to the reflector. A calibration file, recording the relationship between the induced magnetic field intensity and the distance, is developed for each unique type of reflector produced by the manufacturer. Reflectors are usually either round or square galvanized sheet steel about 0.6 mm (0.02 i
9、n.) thick. They usually range in size depending on the anticipated thickness of the pavement to be measured. For pavements up to 350 mm (13.8 in.) thick, round 300-mm (11.8-in.) diameter reflectors are adequate. Square 355-mm (14.0-in.) reflectors are adequate for pavements up to 500 mm (19.7 in.) t
10、hick. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3c T 359M/T 359-2 AASHTO 4. SIGNIFICANCE AND USE 4.1. This test method covers the indirect measurement of the pavement thickness to provide a rap
11、id, nondestructive result. The method is used to determine the compliance of concrete pavement construction with the thickness specifications. The nondestructive thickness results have shown good correlation with direct measurement of pavement thickness using T 148 (see the reference listed in Secti
12、on 12.1.). 5. INTERFERENCES 5.1. This test method can produce misleading results when metal is nearby. Steel-toe shoes can also affect the results if the operator steps too close to the gauge head during the measurement process. 6. APPARATUS 6.1. An electromagnetic pulse induction device that genera
13、tes a variant magnetic field that creates an eddy current in a reflector capable of measuring pavement thickness. 6.2. A metal reflector that can be detected by sensors of the pulse induction device. The type of metal and the size of the reflector depend on the type and thickness of pavement that is
14、 being measured. For deeper sections, larger reflectors are needed since they create a larger magnetic field. Note 1The metal reflectors should conform to the manufacturers specifications. 7. PROCEDURE 7.1. Place metal reflectors at required locations prior to paving. It is usually necessary to fast
15、en the reflectors to the base or subbase to prevent their movement during the paving operation. Place the reflectors at least 1 m (3.3 ft) from any steel or dowel bars. Record or mark the approximate location reference for the reflector for ease of locating after paving. Note 2Reflectors could be fa
16、stened using nails or epoxy. Bright common, galvanized, and coated nails as well as masonry nails up to 90 mm (31/2in.) have worked well. Use of more than three nails per reflector could affect the accuracy of the readings and therefore is not recommended. 7.2. Once the pavement is sufficiently cure
17、d to support foot traffic, use the gauge search mode to locate the reflector center. This is done by holding the gauge head 50 to 75 mm (2 to 3 in.) above the pavement and moving it side to side and forward and backward. When the gauge search function is showing the strongest signal, place a mark di
18、rectly above the reflector on the pavement with chalk or paint as shown in Figure 1. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3c T 359M/T 359-3 AASHTO Figure 1Magnetic Pulse Induction Gauge Se
19、nsor in Operation 7.3. Remove all debris from the surface of the pavement where the gauge wheels will pass. 7.4. With the gauge switched to the measurement mode, place the front wheel approximately 0.5 m (1.6 ft) before the chalk or paint mark. Press and release the measure button and then slowly pu
20、sh the gauge over the reflector. After the gauge head has traveled approximately 1.8 m (6 ft), the gauge processor will calculate the thickness of pavement above the reflector. 7.5. Repeat steps in Section 7.4 two times and record each individual result. No individual thickness result at a single lo
21、cation should be more than 3 mm (0.1 in.) different than the other two individual thickness results. If the difference is larger than 3 mm (0.1 in.), then take three more individual thickness results at the same location. 7.6. Repeat steps in Sections 7.2 to 7.5 for the remaining locations. 8. CALCU
22、LATION AND INTERPRETATION OF RESULTS 8.1. Average the three individual thickness results and express the average result rounded to the nearest 1 mm (0.04 in.). If the difference between any results is larger than 3 mm (0.1 in.), then discard the set of results. 8.2. When the first set of individual
23、thickness results at a location is discarded, examine the second set of individual thickness results. If the difference between any two individual thickness results in the second set is larger than 3 mm (0.1 in.), then discard the set of results and note that the thickness at that location could not
24、 be determined. If the second set of results is within the above limit, then average the three individual thickness results and express the average result rounded to the nearest 1 mm (0.04 in.). 9. REPORT 9.1. Report the following: 9.1.1. Test location and date of measurement. 2018 by the American A
25、ssociation of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3c T 359M/T 359-4 AASHTO 9.1.2. Metal reflector type used. 9.1.3. Average thickness result rounded to the nearest 1 mm (0.04 in.). 10. PRECISION AND BIAS210.1. Precision: 10
26、.1.1. Single-Operator PrecisionThe within-laboratory single ope rator coefficient of variation (COV) has been found to be 0.3 percent (the “one-sigma” 1s limit per ASTM C802). Therefore, the Average thickness results of two properly conducted tests by the same operator at the same location are not e
27、xpected to differ by more than 0.8 percent. 10.1.2. Multilaboratory PrecisionThe between-laboratory COV has been found to be 0.5 percent (the “one-sigma” 1s limit per ASTM C802). Therefore, the average thickness results of two properly conducted tests from two different users at the same location ar
28、e not expected to differ by more than 1.3 percent. Note 3The precision statement was derived from an Iowa DOT study tha t used 15 pulse induction gauges, 15 operators, three reference platforms, and nine concrete pavement locations of varying thicknesses. 10.2. BiasNo bias has been establis hed for
29、this test method. 11. KEYWORDS 11.1. Concrete; thickness measurement. 12. REFERENCES 12.1. Grove, J., K. Jones, D. Ye, and J. M. Gudimettla. Nondestructive Tests of Thickness Measurements for Concrete Pavements: Tests Really Work. In Transportation Research Record 2268. TRB, National Research Counci
30、l, Washington, DC, 2012. 12.2. Jones, K. and T. Hanson. Interlaboratory Study to Determine the Precision of the MIT Scan T2 for PCC Pavement Thickness. Report MLS-14-01, Iowa Department of Transportation, 2015. 1This full standard was first published in 2016. 2Supporting data have been filed at ASTM headquarters (100 Barr Harbor Drive, Conshohocken, PA 19428-2959) and may be obtained by requesting RR: C-9-1004. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
