AASHTO T 21M T 21-2015 Standard Method of Test for Organic Impurities in Fine Aggregates for Concrete.pdf

1、Standard Method of Test for Organic Impurities in Fine Aggregates for Concrete AASHTO Designation: T 21M/T 21-151,2ASTM Designation: C40/C40M-11 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1c T 21M/T 21-1 AASHT

2、O Standard Method of Test for Organic Impurities in Fine Aggregates for Concrete AASHTO Designation: T 21M/T 21-151,2ASTM Designation: C40/C40M-11 1. SCOPE 1.1. This test method covers two procedures for an approximate determination of the presence of injurious organic compounds in fine aggregates t

3、hat are to be used in hydraulic cement mortar or concrete. One procedure uses a glass color standard and the other uses a standard color solution. 1.2. The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exac

4、t equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.3. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the s

5、afety concerns associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 6, Fine Aggregate fo

6、r Hydraulic Cement Concrete R 16, Regulatory Information for Chemicals Used in AASHTO Tests T 2, Sampling of Aggregates T 71, Effect of Organic Impurities in Fine Aggregate on Strength of Mortar T 248, Reducing Samples of Aggregate to Testing Size 2.2. ASTM Standard: D1544, Standard Test Method for

7、Color of Transparent Liquids (Gardner Color Scale) 3. SIGNIFICANCE AND USE 3.1. This test method is of significance in making a preliminary determination of the acceptability of fine aggregates with respect to the requirements of M 6. 3.2. The principal value of this test method is to furnish a warn

8、ing that organic impurities may be present. When a sample subjected to this test produces a color darker than the standard color, it is advisable to perform the test for the effect of organic impurities on the strength of mortar in accordance with T 71. 2015 by the American Association of State High

9、way and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 21M/T 21-2 AASHTO 4. APPARATUS 4.1. Glass BottlesColorless glass graduated bottles, approximately 240 to 470-mL (8 to 16-oz) nominal capacity, equipped with watertight stoppers or caps, not sol

10、uble in the specified reagents. In no case shall the maximum outside dimension of the bottles, measured along the line of sight used for the color comparison, be greater than 60 mm (2.5 in.) or less than 40 mm (1.5 in.). The graduations on the bottles shall be in milliliters or ounces (U.S. fluid),

11、except that unmarked bottles may be calibrated and scribed with graduations by the user. In such case, graduation marks are required at only three points as follows: 4.1.1. Standard Color Solution Level75 mL, (21/2oz) (U.S. fluid); 4.1.2. Fine Aggregate Level130 mL, (41/2oz) (U.S. fluid); and 4.1.3.

12、 NaOH Solution Level200 mL, (7 oz) (U.S. fluid). 4.2. Glass Color Standard: 4.2.1. Glass color standard shall be used as described in Table 1 of ASTM D1544. Note 1A suitable instrument consists of five glass color standards mounted in a plastic holder. Only the glass identified as Gardner Color Stan

13、dard No. 11, corresponding to organic plate number three, is to be used as the glass color standard in Section 9.1.1. 5. REAGENT AND STANDARD COLOR SOLUTION 5.1. Reagent Sodium Hydroxide Solution (3 percent)Dissolve 3 parts by mass of sodium hydroxide (NaOH) in 97 parts of water. 5.2. Standard Color

14、 SolutionDissolve reagent grade potassium dichromate (K2Cr2O7) in concentrated sulfuric acid (sp gr 1.84) at the rate of 0.250 g/100 mL of acid. The solution must be freshly made for the color comparison, using gentle heat if necessary to effect solution. Preparation of the reference standard color

15、solution is unnecessary when the Glass Color Standard Procedure is used to determine the color value. 6. SAMPLING 6.1. The sample shall be selected in general accordance with T 2. 7. TEST SAMPLE 7.1. Obtain a test sample of fine aggregate of about 450 g (approximately 1 lb) in accordance with T 248.

16、 Sample drying prior to testing, if necessary, shall be done by air drying only. 8. PROCEDURE 8.1. Fill a glass bottle to the 130-mL (approximately 41/2-fluid oz) level with the sample of the fine aggregate to be tested. 2015 by the American Association of State Highway and Transportation Officials.

17、All rights reserved. Duplication is a violation of applicable law.TS-1c T 21M/T 21-3 AASHTO 8.2. Add a 3-percent NaOH solution in water until the volume of the fine aggregate and liquid, indicated after shaking, is 200 mL (approximately 7 fluid oz). 8.3. Stopper the bottle, shake vigorously, and the

18、n allow to stand for 24 h. 9. DETERMINATION OF COLOR VALUE 9.1. Glass Color Standard ProcedureAt the end of the 24-h standing period, visually compare the color standards to the color of the supernatant liquid above the test specimen. Report the organic plate number corresponding to the Gardner Colo

19、r Standard number that is nearest the color of the supernatant liquid. When using this procedure, it is not necessary to prepare the standard color solution. 9.1.1. To define the color of the liquid of the test sample, use five glass standard colors as described in Table 1 of ASTM D1544, using the f

20、ollowing colors: Gardner Color Standard No. Organic Plate No. 5 1 8 2 11 3 (standard) 14 4 16 5 9.2. Standard Color Solution ProcedureAt the end of the 24-h standing period, fill a glass bottle to the 750-mL level (approximately 21/2fluid oz.) with the fresh standard color solution, prepared not lon

21、ger than 21/2h previously, as prescribed in Section 5.2. Hold the bottle with the test solution and the bottle with the standard color solution side by side and compare the color of light transmitted through the supernatant liquid above the test sample with the color of light transmitted through the

22、 standard color solution. Record whether it is lighter, darker, or of equal color to that of the reference standard. 10. INTERPRETATION OF RESULTS 10.1. If the color of the supernatant liquid is darker than that of the glass color standard organic plate No. 3 (Gardner Color Standard No. 11) or the s

23、tandard color solution, the fine aggregate under test shall be considered to possibly contain injurious organic compounds, and further tests should be made before approving the fine aggregate for use in concrete. 11. PRECISION AND BIAS 11.1. Because this test produces no numerical values, determinat

24、ion of the precision and bias is not necessary. 1First published in dual units in 2015. 2This method agrees with ASTM C40/C40M-11, except for shifting of text between Sections 5.2 and 9.2. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.