1、Standard Method of Test for Sampling and Testing for Chloride Ion in Concrete and Concrete Raw Materials AASHTO Designation: T 260-97 (2016) Release: Group 1 (April 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 2000
2、1 TS-3c T 260-1 AASHTO Standard Method of Test for Sampling and Testing for Chloride Ion in Concrete and Concrete Raw Materials AASHTO Designation: T 260-97 (2016) Release: Group 1 (April 2016) 1. SCOPE 1.1. This method covers procedures for the determination of the acid-soluble chloride ion content
3、 or the water-soluble chloride ion content of aggregates, portland cement, mortar, or concrete. 1.2. The total amount of chloride is usually equal to the acid-soluble chloride. However, organic additives or minerals that contain acid-insoluble chloride may be present in concrete and concrete raw mat
4、erials. These constituents may become acid soluble during long-term exposure to the alkaline environment in concrete or mortar. 1.3. The age of concrete mortar or hydrated portland cement at the time of sampling will have an affect on the water-soluble chloride ion content. Therefore, unless early a
5、ge studies are desired, it is recommended that the material be well cured and at least 28 days of age before sampling. 1.4. This standard provides for the determination of chloride ion content by two procedures: Procedure A, Determination of Acid-Soluble Chloride Ion Content and Water-Soluble Chlori
6、de Ion Content by Potentiometric Titration or Ion-Selective Electrode (Laboratory Test Method); and Procedure B, Acid-Soluble Chloride Ion by Atomic Absorption (Laboratory Test Method). 1.5. Sulfides are known to interfere with the determination of chloride content. Blast-furnace slag aggregates and
7、 cements contain sulfide sulfur in concentrations that can cause such interference, which can be eliminated by treatment as noted in the test procedures. Other materials that produce a strong odor of H2S when acid is added to them should be similarly treated. 1.6. The values stated in SI units are t
8、o be regarded as the preferred standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 231, Weighing Devices Used in the Testing of Materials T 2, Sampling of Aggregates T 127, Sampling and Amount of Testing of Hydraulic Cement T 248, Reducing Samples of Aggregate to Testing Size 2.2. ASTM Standa
9、rd: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 260-2 AASHTO 2.3. Other Docume
10、nts: Clear, K. C. Evaluation of Portland Cement Concrete for Permanent Bridge Deck Repair. Report FHWA-RD-74-5. Federal Highway Administration, U.S. Department of Transportation, February 1974. Clemena, G. C., J. W. Reynolds, and R. M. McCormick. Comparative Studies of Chloride in Hardened Concrete.
11、 Report No. FHWA-RD-77-84 77-R7. Virginia Highway and Transportation Research Council, August 1976. PROCEDURE AACID-SOLUBLE CHLORIDE ION CONTENT AND WATER-SOLUBLE CHLORIDE ION CONTENT BY POTENTIOMETRIC TITRATION OR ION-SELECTIVE ELECTRODE (LABORATORY TEST METHOD) 3. APPARATUS 3.1. Sampling Equipment
12、 for Procedures A and B: 3.1.1. Core drill. 3.1.2. Rotary impact-type drill with a depth indicator and drill or pulverizing bits of sufficient diameter to provide a representative sample of sufficient size for testing. 3.1.2.1. Sample containers capable of maintaining the sample in an uncontaminated
13、 state. 3.1.2.2. Spoons of adequate size to collect the sample from the drilled holes. 3.1.2.3. A “blow out” bulb or other suitable means of removing excess pulverized material from the hole prior to redrilling operations. 3.1.2.4. A device capable of determining the location and depth of steel rein
14、forcement to 3 mm (1/8in.). 3.2. Equipment for Chemical Testing: 3.2.1. Chloride ion or silver/sulfide ion selective electrode and manufacturer-recommended filling solutions. Note 1Suggested electrodes are the Orion 96-17 Combination Chloride Electrode or the Orion 94-6 Silver/Sulfide Electrode or e
15、quivalents. The Silver/Sulfide Electrode requires use of an appropriate reference electrode (Orion 90-02 or equivalent). 3.2.2. A millivoltmeter compatible with the ion electrode. Note 2Suggested millivoltmeter is the Orion Model 701 A Digital ph/mV meter or equivalent. 3.2.3. Magnetic stirrer and T
16、eflon stirring bars. 3.2.4. Burette with 0.1-mL graduations. 3.2.5. Balance complying with M 231, Class A. 3.2.6. Balance complying with M 231, Class G 2. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
17、TS-3c T 260-3 AASHTO 3.2.7. Hot plate, 250 to 400C heating surface temperature. 3.2.8. Glassware, 100- and 250-mL beakers, filter funnels, stirring rods, watch glasses, dropper, wash bottles. 3.2.9. Sieve, U.S. Standard 300 m (No. 50). 3.2.10. Whatman No. 40 and No. 41 filter papers (or equivalent).
18、 Note 3If equivalent filter papers are used, they should be checked to confirm they do not contain chloride, which will contaminate the sample. 4. REAGENTS 4.1. Concentrated HNO3(sp gr 1.42). 4.2. Sodium chloride, NaCl, reagent grade (primary standard). 4.3. Standard 0.01 normality NaCl solution. Dr
19、y reagent grade NaCl in an oven at 105C. Cool, in a desiccator, determine the mass of approximately 0.5844 g to the nearest 0.0001 g, dissolve in distilled H2O, and transfer to a 1-L volumetric flask. Make up to the mark with distilled H2O and mix. Calculate the exact normality as follows: ( )actual
20、NaC1()0.01000.5844WN = (1) where: Wactual= actual mass of NaCl; and NNaCl= normality of NaCl solution. 4.4. Standard 0.01 Normality AgNO3Determine the mass of 1.7 g of reagent AgNO3, dissolve in distilled H2O, filter into a 1-L brown glass bottle, fill, and mix thoroughly. Standardize against 25.00
21、mL of the NaCl solution by the titration method given in Section 6.4. Calculate the exact normality as follows: ( )( )33NaC1 NaC1AgNOAgNOVNNV= (2) where: 3AgNON = normality of AgNO3solution; VNaCl= volume (mL) of NaCl solution; NNaCl= normality of NaCl solution; and 3AgNOV = volume (mL) of AgNO3solu
22、tion. 4.5. Distilled Water. Note 4Deionized water may be used in place of distilled water for samples where extreme precision and accuracy are not demanded. 4.6. Methyl Orange Indicator. 4.7. EthanolDenatured, or methanol, technical. 4.8. Hydrogen Peroxide30 percent. 2016 by the American Association
23、 of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 260-4 AASHTO 5. METHOD OF SAMPLING 5.1. Concrete Sample: 5.1.1. Determine the depth within the concrete for which the chloride content is desired. Note 5A convenient method of det
24、ermining the location and depth of reinforcement bars is a pachometer capable of determining the location and depth of steel reinforcement to 3 mm (0.125 in.). 5.1.2. Core MethodDrill the core to chosen depth and retrieve. 5.1.2.1. When samples are received in the laboratory in other than pulverized
25、 condition, the sample shall be crushed and ground to a powder. All sawing or crushing shall be done dry (i.e., without water). All material shall pass a 0.300-mm (No. 50) sieve. All pulverizing tools and sieves shall be washed with alcohol or distilled water and shall be dry before use with each se
26、parate sample. (See Note 7.) 5.1.3. Pulverizing Method: 5.1.3.1. Set the rotary hammer depth indicator so that it will drill to 13 mm (0.5 in.) above the desired depth. 5.1.3.2. Using a drill or pulverizing bit, drill until the depth indicator seats itself on the concrete surface. 5.1.3.3. Thoroughl
27、y clean the drilled hole and surrounding area utilizing the “blow out” bulb or other suitable means. 5.1.3.4. Reset the depth indicator to permit 13 mm (0.5 in.) additional drilling. 5.1.3.5. Pulverize the concrete until the depth indicator again seats itself on the concrete. Note 6Care must be exer
28、cised during this pulverizing operation to prevent the drill bit from abrading concrete from the sides of the hole above the sampling depth. To ensure against this, some users utilize a 6-mm (0.25-in.) smaller diameter bit in this step than that used in Section 5.1.3.2. 5.1.3.6. Collect at least 10
29、g of the material remaining in the hole using a spoon and place in the sample container. 5.1.3.7. If the sample, as collected, does not completely pass a 0.300-mm (No. 50) sieve, additional pulverizing shall be performed in the laboratory until the entire sample is finer than 0.300-mm (No. 50). Note
30、 7During sample collection and pulverizing, personnel shall use caution to prevent contact of the sample with hands, or other sources of body perspiration or contamination. Further, all sampling tools (drill bits, spoons, bottles, sieves, etc.) shall be washed with alcohol or distilled water and sha
31、ll be dry prior to use on each separate sample. Alcohol is normally preferred for washing because of the rapid drying that naturally occurs. 5.2. Raw Material Sample: 5.2.1. Cement samples shall be taken and prepared as prescribed in T 127. 5.2.2. Coarse and fine aggregate samples shall be taken as
32、prescribed in T 2. Samples shall be reduced in accordance with T 248. 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 260-5 AASHTO 5.2.3. Test samples shall contain the following minimum sizes: C
33、ement100 g; Sand300 g; Coarse aggregate3000 g. 5.2.4. Coarse aggregate samples shall be crushed to pass a 4.75-mm (No. 4) sieve and then reduced down to about 300 g. The final 300 g of coarse or fine aggregate shall be ground to a minus 0.300-mm (No. 50) sieve. 6. PROCEDURE Two distinct procedures a
34、re presented here for determination of acid-soluble chloride ion or water-soluble chloride ion content. For acid-soluble chloride ion content follow Sections 6.1 and 6.2, then continue with Section 6.4. For water-soluble chloride ion content follow Sections 6.1 and 6.3, then continue with Section 6.
35、4. 6.1. Determine the mass to the nearest milligram of a 3-g powdered sample representative of the material under tests. Note 8Some users dry the sample to constant mass in a 105C oven and determine the dry sample prior to analysis. This optional procedure provides a constant base for comparison of
36、all results by eliminating moisture content as a variable. It is generally believed that drying is necessary only when very high accuracy is desired. 6.2. Procedure for Acid-Soluble Chloride Ion Content: 6.2.1. Transfer the sample quantitatively to a beaker; add 10 mL of distilled H2O, swirling to b
37、ring the powder into suspension. Add 3 mL of concentrated HNO3with continued swirling until the material is completely decomposed. Break up any lumps with a stirring rod and dilute with hot H2O to 50 mL. Stir thoroughly to ensure complete sample digestion. If the sample contains blast-furnace slag o
38、r other sulfide-bearing material, add 3 mL of hydrogen peroxide (30 percent solution). Add 5 drops of methyl orange indicator and stir. If yellow to yellow-orange color appears, solution is not sufficiently acidic. Add additional concentrated HNO3dropwise with continuous stirring until a faint pink
39、or red color persists in the solution. Cover with a watch glass, retaining the stirring rod in the beaker. Heat the acid solution or slurry to boiling on a hot plate at medium heat (250 to 400C) and boil for about 1 min. Remove from the hot plate and filter through double filter paper (Whatman No. 4
40、1 over No. 40 filter paper or equivalent). 6.2.2. Wash the filter paper 10 times with hot distilled H2O, being careful not to lift the paper away from the funnel surface. Finally, lift the filter paper carefully from the funnel and wash the outside surface of the paper with hot distilled H2O; then w
41、ash the tip of the funnel. The final volume of the filtered solution should be 125 to 150 mL. Cover with a watch glass and allow to cool to room temperature in an HCl fume-free atmosphere. Note 9Due to the presence of relatively insoluble materials in the sample, the solution generally will have a s
42、trong gray color, making the detection of indicator color difficult at times. Running of several trial samples is suggested to give the analyst practice in detecting the indicator color. Note 10A sample prepared to 100 percent passing 0.300-mm (No. 50) sieve should generally allow determination of a
43、ny expected chloride level with adequate precision and accuracy. Samples containing highly siliceous aggregates may require finer grinding to minimize bumping during the procedure in Section 6.2. This may also be the case when the concrete contains modifiers such as latex or polymer. 2016 by the Ame
44、rican Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 260-6 AASHTO 6.3. Procedure for Water-Soluble Chloride Ion Content: 6.3.1. Transfer the sample quantitatively to a beaker and add 6070 mL distilled H2O. Cover the
45、 beaker with a watch glass and bring to a boil on a hot plate-magnetic stirrer using a small magnet. Boil for 5 min, then let stand for 24 h in an HCl fume-free atmosphere. 6.3.2. Filter the clear supernatant liquid in the beaker through double filter paper (Whatman No. 41 over No. 40 or equivalent)
46、 into a 250-mL beaker; take care to quantitatively transfer any adhering drops on the watch glass, and use a stirring rod to aid transfer. Add sufficient hot distilled H2O to cover any residue left in the original beaker, stir 1 min on a magnetic stirrer, and filter into the 250-mL beaker with a swi
47、rling action. Wash the beaker and the stirring rod once into the filter with hot distilled H2O. Wash the filter paper once with hot distilled H2O. Lift the filter paper carefully from the funnel and wash the outside surface of the paper with hot distilled H2O. Set aside the paper and wash the interi
48、or of the funnel and its tip with hot distilled H2O. Finally, add 12 drops of methyl orange indicator to the 150-mL beaker; then add concentrated HNO3dropwise with continuous stirring until a permanent pink to red color is obtained. If the sample contains blast-furnace slag or other sulfide-bearing
49、material, add 3 mL of hydrogen peroxide (30-percent solution). Make up the volume to 125 to 150 mL with distilled H2O. 6.4. Three alternate methods are available to determine the Clcontent of the solution. All methods utilize an ion selective electrode (Clor Ag+) and all methods for the purpose of this analysis give results of essentially equal accuracy and precision. 6.4.1. Method 1: Potentiometric TitrationFill the Clor the Ag+electrode with the solution(s) recommended by the manufacturer, plug it into the millivoltmeter (preferab
