1、Standard Specification for Detecting the Presence of Phosphorous in Asphalt Binder AASHTO Designation: TP 78-09 (2013)1American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2b TP 78-1 AASHTO Standard Specification for De
2、tecting the Presence of Phosphorous in Asphalt Binder AASHTO Designation: TP 78-09 (2013)11. SCOPE 1.1. This qualitative test method can be used to identify the presence of polyphosphoric acid (PPA) in asphalt binder or residue. If PPA is present in the binder, a blue color is developed in approxima
3、tely 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. It is not specific for the presence of PPA. A positive test result assumes that the phosphorus is from PPA. Any additive that
4、 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 purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this sta
5、ndard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: T 40, Sampling Bituminous Materials 3. SUMMARY OF TEST METHOD 3.1. Butyl alcohol is used to extract some of the acid presen
6、t 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 antimonyl tartrate, and ascorbic acid to form a blue color. 4. SIGNIFICANCE 4.1. Phosphoric acid may be added to asphalt binder to
7、 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 either positive or negative that phosphoric acid is present. 5. APPARATUS 5.1. PipetteDisposable, plastic transfer pipettes. 5.2
8、. ContainersOne-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 2014 by the Amer
9、ican Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 78-2 AASHTO water. Commercial detergents should not be used to clean the glassware because they may contain phosphates, which will interfere with the results. Not
10、e 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 positive result in this test even with the empty can. If there is doubt about the condition of the containers being used, th
11、en 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 tartrate hydrate C8H4K2O12Sb2H2O in 50 mL of distilled water. Add 5.6 g of ammonium molybdate (NH4)6Mo7O244 H2O and swir
12、l 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 antimonyl tartrate/ammonium molybdate solution from Section 6.1 with approximately 950 mL of 1 N sulfuric acid solution.
13、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. This solution is stable for 1 year. 6.4. Ascorbic Acid Color ReagentDissolve 0.50 g of L-ascorbic acid C6H8O6 in 100 mL
14、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. Sample the material in accordance with T 40. See Note 2 regarding potential concerns regarding contamination of samplin
15、g 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 the asphalt is fluid. 8.3. Remove the container, and immediately add 2 mL of butyl alcohol while stirring the container.
16、 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 the color reagent, stop stirring and allow the sample to sit for 5 to 10 min. 8.6. If phosphoric acid is present in the as
17、phalt, 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 color may either fade or intensify after 30 min. 8.7. If a blue color appears, the sample is reported as “positive.” The
18、sample is reported as “negative” if it does not turn blue. 2014 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 78-3 AASHTO Note 3The blue color, if present, will be in the aqueous phase, which will
19、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. This report shall include the following: 9.1.1. Identification of sample. 9.1.2. “Positive” or “Negative” result. 10. PRECI
20、SION 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 only be defined in terms of this test method. 11. KEYWORDS 11.1. Asphalt; phosphoric acid; PPA. 1This provisional standard was first published in 2009. 2014 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
