1、Standard Method of Test for Detecting the Presence of Phosphorous in Asphalt Binder AASHTO Designation: T 377-171Technical Section: 2b, Liquid Asphalt Release: Group 3 (August 2017) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington
2、, D.C. 20001 TS-2b T 377-1 AASHTO Standard Method of Test for Detecting the Presence of Phosphorous in Asphalt Binder AASHTO Designation: T 377-171Technical Section: 2b, Liquid Asphalt Release: Group 3 (August 2017) 1. SCOPE 1.1. This qualitative test method can be used to identify the presence of p
3、olyphosphoric acid (PPA) in asphalt binder or residue. If PPA is present in the binder, a blue color is developed in approximately 5 min. The test method is not quantitative, but it can detect PPA at concentrations as low as 0.1 percent. The test method can only determine the presence of phosphorus.
4、 It is not specific for the presence of PPA. A positive test result assumes that the phosphorus is from PPA. Any additive that contains phosphorus will give a false positive for the presence of PPA. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. This standard does not pu
5、rport 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 regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standar
6、d: R 66, Sampling Asphalt Materials 3. SUMMARY OF TEST METHOD 3.1. Butyl alcohol is used to extract some of the acid present from the asphalt. The extracted acid is then transferred to the water phase. The presence of phosphoric acid is detected by reaction with ammonium molybdate, potassium antimon
7、yl tartrate, and ascorbic acid to form a blue color. 4. SIGNIFICANCE 4.1. Phosphoric acid may be added to asphalt binder to modify the physical properties of the binder. This test method detects the presence of phosphoric acid in the asphalt binder but is not a quantitative test. The result is eithe
8、r positive or negative that phosphoric acid is present. 5. APPARATUS 5.1. PipetDisposable, plastic transfer pipets. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b T 377-2 AASHTO 5.2. ContainersOn
9、e-ounce cans, test tubes, or small beakers. Disposable cans or glassware are recommended to avoid contamination. If glassware is reused, it must be washed with hot (1 + 3) hydrochloric acid (1 part hydrochloric acid to 3 parts distilled water) and rinsed with distilled water. Commercial detergents s
10、hould not be used to clean the glassware because they may contain phosphates, which will interfere with the results. Note 1One agency found that the cans they were using for this test had been lubricated during the manufacturing process with a lubricant containing phosphates. This resulted in a posi
11、tive result in this test even with the empty can. If there is doubt about the condition of the containers being used, then take the precaution of running a blank test with no asphalt. 6. REAGENTS AND MATERIALS 6.1. Antimonyl Tartrate/Ammonium Molybdate SolutionDissolve 0.13 g of potassium antimonyl
12、tartrate hydrate C8H4K2O12Sb2H2O in 50 mL of distilled water. Add 5.6 g of ammonium molybdate (NH4)6Mo7O244 H2O and swirl until dissolved. 6.2. Sulfuric Acid Solution1 N solution of sulfuric acid H2SO4. Sulfuric acid solution can be purchased in 1-L polyethylene bottles. 6.3. Stock SolutionMix the a
13、ntimonyl tartrate/ammonium molybdate solution from Section 6.1 with approximately 950 mL of 1 N sulfuric acid solution. This can be done by adding the solution from Section 6.1 to 1 L of 1 N sulfuric acid if there is sufficient space in the bottle. The exact amount of sulfuric acid is not critical.
14、This solution is stable for 1 year. 6.4. Ascorbic Acid Color ReagentDissolve 0.50 g of L-ascorbic acid C6H8O6 in 100 mL of the stock solution from Section 6.3. Prepare the reagent fresh daily as needed. 6.5. Butyl AlcoholIsobutanol (CH3)2CHCH2OH or n-butanol CH3(CH2)3OH may be used. 7. SAMPLING 7.1.
15、 Sample the material in accordance with R 66. See Note 2 regarding potential concerns regarding contamination of sampling container. 8. PROCEDURE 8.1. Heat the asphalt and pour 1 to 2 g into a 1-oz can or other small container. 8.2. Place the container in an oven set at 163 10C for 10 min to ensure
16、the asphalt is fluid. 8.3. Remove the container, and immediately add 2 mL of butyl alcohol while stirring the container. 8.4. Continue to stir the container and add 2 mL of distilled water. 8.5. While still stirring the container, add 2 mL of the ascorbic acid color reagent. After the addition of th
17、e color reagent, stop stirring and allow the sample to sit for 5 to 10 min. 8.6. If phosphoric acid is present in the asphalt, a blue color will develop within 5 to 10 min. Decant the solution into a second container if unable to see the color. Note 2After 30 min, the results are not reliable. The c
18、olor may either fade or intensify after 30 min. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b T 377-3 AASHTO 8.7. If a blue color appears, the sample is reported as “positive.” The sample is rep
19、orted as “negative” if it does not turn blue. Note 3The blue color, if present, will be in the aqueous phase, which will be at the bottom. Often the top layer has a brown or green color. 8.8. When new reagents are prepared, prepare and run a blank (asphalt with no phosphoric acid). 9. REPORT 9.1. Th
20、is report shall include the following: 9.1.1. Identification of sample. 9.1.2. “Positive” or “Negative” result. 10. PRECISION AND BIAS 10.1. PrecisionThe research required to develop precision estimates has not been conducted. 10.2. BiasThis test method has no bias since the values determined can on
21、ly be defined in terms of this test method. 11. KEYWORDS 11.1. Asphalt; phosphoric acid; PPA. 1Formerly AASHTO Provisional Standard TP 78. 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.
