1、Standard Method of Test for Identification of Iron-Based Alloy Steel Bars for Concrete Reinforcement or Dowels by Handheld X-Ray Fluorescence (XRF) Spectrometer AASHTO Designation: T 375M/T 375-171Technical Section: 4f, Metals Release: Group 2 (June 2017) American Association of State Highway and Tr
2、ansportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001TS 4f T 375M/T 375-1 AASHTO Standard Method of Test for Identification of Iron-Based Alloy Steel Bars for Concrete Reinforcement or Dowels by Handheld X-Ray Fluorescence (XRF) Spectrometer AASHTO Designation: T 375
3、M/T 375-171Technical Section: 4f, Metals Release: Group 2 (June 2017) 1. SCOPE 1.1. This test method covers the procedure to be used in identifying the composition of iron-based alloy steel bars for concrete reinforcement or dowels using X-ray fluorescence (XRF) spectrometer. 1.2. The values stated
4、in SI units are to be regarded as the standard. 1.3. 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 and health practices and determine the applicability of re
5、gulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 31M/M 31, Deformed and Plain Carbon and Low-Alloy Steel Bars for Concrete Reinforcement M 334M/M 334, Uncoated, Corrosion-Resistant, Deformed and Plain Chromium Alloyed, Billet-Steel Bars for Concrete Reinforcement a
6、nd Dowels 2.2. ASTM Standards: A276/A276M, Standard Specification for Stainless Steel Bars and Shapes A955/A955M, Standard Specification for Deformed and Plain Stainless-Steel Bars for Concrete Reinforcement 2.3. Other Document: The XRF manufacturers safety and instrument operating procedures and lo
7、cal documents regulating the use of low-level X-ray testing equipment. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS 4f T 375M/T 375-2 AASHTO 3. SIGNIFICANCE AND USE 3.1. This method is used to qui
8、ckly identify the composition of iron-based alloys using a field-ready, handheld XRF spectrometer. The alloy type for reinforcing steel bars can be identified and sorted in the field using the XRF spectrometer. This spectrometer may also be used to verify the alloy of reinforcing bars submitted to t
9、he laboratory for testing from a project. 4. TEST APPARATUS 4.1. XRF SpectrometerA commercially produced field-ready, handheld X-ray fluorescence spectrometer setup and calibrated to analyze chemical elements and determine the alloy of iron-based steels. Note 1Follow all manufacturer or age ncy safe
10、ty precautions when operating apparatus. 5. TEST SPECIMENS 5.1. The test surface of the iron-based alloy must be free of corrosion, mill scale, and oils. The surface may need to be cleaned using a wire brush and a suitable solvent. 5.2. Standardized metal coupons of known composition are needed to v
11、erify that the XRF is operating properly and its factory calibration is currently valid. 6. CALIBRATION AND STANDARDIZATION 6.1. XRF SpectrometerThe XRF spectrometer comes from the manufacturer calibrated. A calibration standard must be purchased to verify the XRF is operating properly before and af
12、ter each use. The calibration verification standard should have a NIST traceable calibration certification. It is recommended that the calibration verification standard be of a similar alloy to the one(s) tested. It is preferable that multiple calibration verification standards be on hand that cover
13、 the range of alloys being tested. 7. PROCEDURE 7.1. Turn the XRF spectrometer on and allow time for the XRF spectrometer to go through its preprogrammed initializing and equipment check. 7.2. Perform the test in accordance with the XRF spectrometer manufacturers recommendations. 7.3. Perform checks
14、 7.3.1. Test the calibration verification standard to determine if the XRF Spectrometer is capable of identifying the alloy and is providing results within the manufacturers elemental tolerances shown on the calibration certification of the calibration verification standard. If the XRF spectrometer
15、 results are within acceptable tolerances, proceed with analysis. 7.3.2. If the XRF spectrometer results are not within acceptable tolerances, the instrument may need to go back to the manufacturer for cleaning and repair. 7.3.3. Alloy identification should occur within seconds of initiating analysi
16、s; however, longer analysis time is needed for greater accuracy. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS 4f T 375M/T 375-3 AASHTO 8. CALCULATIONS 8.1. Calculations are not required. The XRF s
17、pectrometer provides user-ready data. The results are typically reported in percentages. This is desirable since the alloy types listed in ASTM A276/A276M and A955/A955M, and M 334M/M 334 are provided in elemental percentages. 9. REPORT AND INTERPRETATION OF RESULTS 9.1. Report the following informa
18、tion: 9.1.1. Sample identification; 9.1.2. Alloy; and 9.1.3. Percent confidence of alloy ID. 9.2. Elements analyzed expressed in percent and as screened to clearly identify the alloy per ASTM A276/A276M, A955/A955M, and M 334M/M 334. Typically, the elements that will be used to identify an alloy wil
19、l be manganese, chromium, nickel, molybdenum, 9.3. The XRF spectrometer will typically provide the alloy type, percent confidence of alloy ID, list of percent elements detected, and confidence limit per element detected. The elemental composition should be checked against the values listed in M 334M
20、/M 334 Table 1 or appropriate documentation from the supplier. Results from this test should be recorded according to the purchasers guidelines. Note 2The XRF spectrometer reports th e elements detected in the sample and elements that are below the detection limit. For an element to be detected by a
21、n XRF spectrometer in a given sample, the measured concentration of the sample must be at least three times the standard deviation of the measurement. This detection limit will depend on the composition of the sample. The precision of each measurement is two times the standard deviation. An element
22、is classified as “detected” if the measured concentration is at least 1.5 times the precision. Detected elements are displayed in percent, followed by the measurement precision. Non-detected elements are shown as the detection limit (LOD limit of detection) for that sample. The detection limit for a
23、 given element varies depending on the other elements in the matrix, the strength of the X-ray signal from the metal and the environment between the XRF spectrometer detector and the metal surface. The information in this note is typical of most XRF spectrometers, but may not apply to all manufactur
24、ed models. 10. PRECISION AND BIAS 10.1. PrecisionThe research required to develo p precision estimates has not been conducted. 10.2. BiasThe research required to establish the bias has not been condu cted. 11. KEYWORDS 11.1. Iron-based alloy steel bars; X-ray fluorescence; XRF Spectrometer. 1Formerly AASHTO Provisional Standard MP 18M/MP 18, Annex B1. First published as a full standard in 2017. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
