1、Standard Method of Test for Pavement Thickness by Magnetic Pulse Induction AASHTO Designation: T 359-161 Release: Group 1 (April 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 359-1 AASHTO Standard Meth
2、od of Test for Pavement Thickness by Magnetic Pulse Induction AASHTO Designation: T 359-161Release: Group 1 (April 2016) 1. SCOPE 1.1. This test method covers the determination of the pavement thickness by using magnetic pulse induction. This method is intended for use with plain jointed concrete pa
3、vements, 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. 1.2. The values stated in SI units are to
4、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 appropriate safety and health practices and determine the applicability of regulatory limitation
5、s prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: T 148, Measuring Length of Drilled Concrete Cores 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 gen
6、erates a variant magnetic field that creates an 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 d
7、etermined primarily by the distance from the device to the target. 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
8、galvanized sheet steel about 0.6 mm thick. They usually range in size depending on the anticipated thickness of the pavement to be measured. For pavements up to 350 mm thick, round 300-mm diameter reflectors are adequate. Square 355-mm reflectors are adequate for pavements up to 500 mm thick. 4. SIG
9、NIFICANCE AND USE 4.1. This test method covers the indirect measurement of the pavement thickness to provide a rapid, nondestructive result. The method is used to determine the compliance of concrete pavement construction with the thickness specifications. The nondestructive thickness results have s
10、hown good correlation with direct measurement of pavement thickness using T 148 (References 12.1.).2 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 359-2 AASHTO 5. INTERFERENCES 5.1. This test m
11、ethod 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 generates a variant magnetic field that creates an
12、 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 being measured. For deeper sections, larger
13、 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 targets at required locations prior to paving. It is usually necessary to fasten the reflectors to the base or subbase to prevent t
14、heir movement during the paving operation. Place the reflectors at least 1 m 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 fastened using nails or epoxy. Bright common, galvanized, and co
15、ated nails as well as masonry nails up to 3 in. 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 cured to support foot traffic, use the gauge search mode to locate the refle
16、ctor center. This is done by holding the gauge head 50 to 75 mm 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 directly above the reflector on the pavement with chalk or paint as shown in Figure 1.
17、Figure 1Magnetic Pulse Induction Gauge Sensor in Operation 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 359-3 AASHTO 7.3. Remove all debris from the surface of the pavement where the gauge whe
18、els will pass. 7.4. With the gauge switched to the measurement mode, place the front wheel approximately 0.5 m before the chalk or paint mark. Press the measure button and then slowly push the gauge over the reflector. After the gauge head has traveled approximately 1.8 m, the gauge processor will c
19、alculate the thickness of pavement above the reflector. 7.5. Repeat 10.4 two times and record the results. No result at a single location should be more than 3 mm different than the other two results. If the difference is larger than 3 mm, then take three more tests. 7.6. Repeat 7.2 to 7.5 for the r
20、emaining locations. 8. CALCULATION AND INTERPRETATION OF RESULTS 8.1. Average the 3 readings and express the result to the nearest 1 mm. If the difference between any results is larger than 3 mm, then discard the set of results. 8.2. When the first set of results is discarded, examine the second set
21、 of test results. If the difference between any results in the second set is larger than 3 mm, then discard the set of results and note that the thickness at that location could not be determined. If the second set of results is within the above limit, then average the 3 results and express the resu
22、lt to the nearest 1 mm. 9. REPORT 9.1. Report the following: 9.1.1. Test Location and date of measurement. 9.1.2. Metal target type used. 9.1.3. Average thickness result rounded to the nearest 1mm. 10. PRECISION AND BIAS 10.1. Precision and BiasNo precision and bias statements are available at this
23、time. Note 3These numbers represent, respectively, the (1s percent) and (d2s percent) limits as described in ASTM C670.311. KEYWORDS 11.1. Concrete; thickness measurement. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation o
24、f applicable law.TS-3c T 359-4 AASHTO 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. Transportation Research Board, National Research Council, Was
25、hington, DC, 2012. 1This full standard was first published in 2016. 2The numbers in parentheses refer to the list of references at the end of this standard. 3Supporting 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. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
