1、Standard Method of Test for Accelerated Detection of Potentially Deleterious Expansion of Mortar Bars Due to Alkali-Silica Reaction AASHTO Designation: T 303-00 (2012)1American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 T
2、S-1c T 303-1 AASHTO Standard Method of Test for Accelerated Detection of Potentially Deleterious Expansion of Mortar Bars Due to Alkali-Silica Reaction AASHTO Designation: T 303-00 (2012)11. SCOPE 1.1. This test method allows detection within 16 days of the potential for deleterious expansion of mor
3、tar bars due to the alkali-silica reaction. 1.2. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safe
4、ty and health practices and determine the applicability of regulatory limitations prior to use. A specific precautionary statement is given in Note 3. 1.3. The values stated in SI units are to be regarded as standard. The values in inch-pound units are shown in parentheses, and are for informational
5、 purposes only. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 85, Portland Cement M 92, Wire-Cloth Sieves for Testing Purposes M 201, Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes M 210M/M 210, Use of Apparatus for the De
6、termination of Length Change of Hardened Cement Paste, Mortar, and Concrete R 16, Regulatory Information for Chemicals Used in AASHTO Tests T 106M/T 106, Compressive Strength of Hydraulic Cement Mortar (Using 50-mm or 2-in. Cube Specimens) T 162, Mechanical Mixing of Hydraulic Cement Pastes and Mort
7、ars of Plastic Consistency 2.2. ASTM Standards: C295/C295M, Standard Guide for Petrographic Examination of Aggregates for Concrete C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials C856, Standard Practice for Petrographic Examination of H
8、ardened Concrete D1193, Standard Specification for Reagent Water 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 303-2 AASHTO 3. SIGNIFICANCE AND USE 3.1. This test method provides a means of det
9、ecting the potential of an aggregate used in concrete for undergoing alkali-silica reaction and resulting in potentially deleterious internal expansion. It is based on the NBRI accelerated test method (Davies and Oberholster, 1987a; Davies and Oberholster, 1987b; Hooton and Rogers, 1989; and Oberhol
10、ster and Davies, 1986). 3.2. When expansions greater than 0.10 percent are developed within 16 days from casting, it is recommended that supplementary information be developed to confirm that the expansion is actually due to alkali reactivity. Sources of such supplementary information include: (1) p
11、etrographic examination of the aggregate by ASTM C295/C295M to determine if known reactive constituents are present; and (2) examination of the specimens after tests by ASTM C856 to identify the products of alkali reactivity. 3.3. When it has been concluded from the results of tests performed using
12、this test method and supplementary information that a given aggregate should be considered potentially deleteriously reactive, additional studies, using alternative methods, may be appropriate to develop further information on the potential reactivity. 4. APPARATUS 4.1. The apparatus shall conform t
13、o M 210M/M 210, except as follows: 4.2. SieveSquare-hole, woven-wire, cloth sieves, shall conform to the requirements of M 92. 4.3. Mixer, Paddle, and Mixing BowlMixer, paddle, and mixing bowl shall conform to the requirements of T 162, except that the clearance between the lower end of the paddle a
14、nd the bottom of the bowl shall be 5.1 0.3 mm (0.20 0.01 in.). 4.4. Tamper and TrowelThe tamper and trowel shall conform to T 106M/T 106. 4.5. ContainersThe containers shall permit the test specimens to be totally immersed in either water or 1.0 normal NaOH solution. The containers shall be made of
15、material that can withstand prolonged exposure to 80C (176F) and shall be inert to a 1.0 normal NaOH solution. The containers shall be equipped with tight-fitting covers, seals, or both. The containers shall be constructed in a manner that permits test specimens to be supported, without using the ga
16、uge studs, so that the solution has access to the whole test specimen, and the specimens do not touch the sides of the container or each other. Note 1The NaOH solution will corrode glass or metal containers. Polypropylene containers are recommended. 4.6. OvenA thermostatically controlled oven capabl
17、e of maintaining a temperature of 80.0 1.7C (176 3F) or a thermostatically controlled water bath capable of maintaining the same temperature range. 4.7. Moist Room or ClosetThe moist closet or room shall conform to M 201. 2015 by the American Association of State Highway and Transportation Officials
18、.All rights reserved. Duplication is a violation of applicable law.TS-1c T 303-3 AASHTO 5. REAGENTS 5.1. Sodium Hydroxide (NaOH)USP or technical grade may be used, provided the Na+and OHconcentrations are shown by chemical analysis to lie between 0.99 and 1.01 normal. 5.2. Purity of WaterUnless othe
19、rwise indicated, water shall be reagent Type IV water conforming to ASTM D1193. 5.3. Sodium Hydroxide SolutionEach liter of solution shall contain 40 g of NaOH dissolved in 900 mL of water, and shall be diluted with additional distilled or deionized water to obtain 1 L of solution. The volume propor
20、tion of sodium hydroxide solution to mortar bars in a storage container shall be 4.5 1.0 volumes of solution to one volume of mortar bars. Note 2The volume of a mortar bar may be taken as 184 mL (11.25 in.3). Note 3Precaution: Before using NaOH, review: (1) the safety precautions for using NaOH; (2)
21、 first aid for burns; and (3) the emergency response to spills, as described in the manufacturers Material Safety Data Sheet or other reliable safety literature. NaOH can cause very severe burns and injury to unprotected skin and eyes. Suitable personal protective equipment should always be used. Th
22、ese should include full-face shields, rubber aprons, and gloves impervious to NaOH. Gloves should be checked periodically for pinholes. 6. CONDITIONING 6.1. Maintain the temperature of the molding room and dry materials at no less than 20C (68F) and no more than 27.5C (81.5F). Maintain the temperatu
23、re of the mixing water, and of the moist closet or moist room, at 23.0 1.7C (73.4 3.0F). 6.2. The relative humidity of the molding room shall be not less than 50 percent. 6.3. Maintain the storage oven in which the specimens are stored in the containers at a temperature of 80.0 1.7C (176 3F). 7. SAM
24、PLING AND PREPARATION OF TEST SPECIMENS 7.1. Selection of AggregateProcess materials proposed for use as fine aggregate in concrete as described in Section 7.2 with a minimum of crushing. Process materials proposed for use as coarse aggregate in concrete by crushing to produce as nearly as practical
25、 a graded product from which a sample can be obtained. The sample shall have the grading as prescribed in Section 7.2 and be representative of the composition of the coarse aggregate as proposed for use. 7.1.1. When a given quarried material is proposed for use both as coarse and as fine aggregate,
26、test the material only by selection of an appropriate sample crushed to the fine aggregate sizes, unless there is reason to expect that the coarser size fractions have a different composition than the finer sizes and that these differences might significantly affect expansion due to reaction with th
27、e alkalies in cement. In this case, the coarser-size fractions shall be tested in a manner similar to that employed in testing the fine aggregate sizes. 7.2. Preparation of AggregateGrade all aggregates in accordance with the requirements prescribed in Table 1. Crush aggregates for which sufficient
28、quantities of the sizes specified in Table 1 do not exist until the required material has been produced. In the case of aggregates containing insufficient amounts of one or more of the larger sizes listed in Table 1, and if no larger material is available for crushing, the first size in which suffic
29、ient material is available shall contain the cumulative percentage of material down to that size as determined from the grading specified in Table 1. Note in the test report when such procedures are required. After the aggregate has been 2015 by the American Association of State Highway and Transpor
30、tation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 303-4 AASHTO separated into the various sieve sizes, wash each size with a water spray over the sieve to remove adhering dust and fine particles from the aggregate. Dry the portions retained on the various sie
31、ves and, unless used immediately, store each portion individually in a clean container. Seal the container to prevent moisture loss or gain. Table 1Grading Requirements Passing Sieve Size Retained on Sieve Size Mass, Percent 4.75 mm (No. 4) 2.36 mm (No. 8) 10 2.36 mm (No. 8) 1.18 mm (No. 16) 25 1.18
32、 mm (No. 16) 600 m (No. 30) 25 600 m (No. 30) 300 m (No. 50) 25 300 m (No. 50) 150 m (No. 100) 15 7.3. Selection and Preparation of CementSelect a reference cement that meets the requirements of M 85. Pass the reference cement through a 850-m (No. 20) sieve to remove lumps before use. 7.4. Preparati
33、on of Test Specimens: 7.4.1. Prepare at least three test specimens for each cementaggregate combination. 7.4.2. Prepare the specimen molds in accordance with the requirements of M 210M/M 210, except cover the interior surfaces of the mold with a release agent. Note 4A release agent is acceptable if
34、it serves as a parting agent without affecting the setting of the cement and without leaving any residue that will inhibit the penetration of water into the specimen. TFE-fluorocarbon tape complies with the requirements for a mold release agent. 7.4.3. Proportion the dry materials for the test morta
35、r using 1 part of cement to 2.25 parts of graded aggregate by mass. Mix 440 g of cement and 990 g of dry aggregate (made up by recombining the portions retained on the various sieves in the grading prescribed in Table 1) at one time to prepare a batch of mortar sufficient for making three specimens.
36、 Use a water-to-cement ratio equal to 0.50 by mass. 7.4.4. Mix the mortar in accordance with the requirements of T 162 using water that meets the requirements of Section 5.2. 7.4.5. Mold test specimens with a total elapsed time of not more than 135 s after completion of the original mixing of the mo
37、rtar batch. Fill the molds with two approximately equal layers, each layer being compacted with the tamper. Work the mortar into the corners, around the gauge studs, and along the surfaces of the mold with the tamper until a homogeneous specimen is obtained. After the top layer has been compacted, c
38、ut off the mortar flush with the top of the mold and smooth the surface with a few strokes of the trowel. 8. PROCEDURE 8.1. Place each mold in the moist cabinet or moist room immediately after it has been filled. Cure the specimens in the molds for 24 2 h. Remove the specimens from the molds and, wh
39、ile they are being protected from loss of moisture, properly identify and determine the initial length of each specimen using the length comparator. Record all length measurements to the nearest 0.002 mm (0.0001 in.). 2015 by the American Association of State Highway and Transportation Officials.All
40、 rights reserved. Duplication is a violation of applicable law.TS-1c T 303-5 AASHTO 8.2. Place the specimens of each aggregate sample in a storage container with sufficient tap water to totally immerse them. Seal the containers and place them in an oven maintained at 80.0 1.7C (176 3F) for a period
41、of 24 h. 8.3. Measure the comparator bar prior to measuring each set of specimens because the heat from the mortar bars may cause the length of the comparator to change. If the length of the comparator bar has changed, wait until the comparator has returned to room temperature before remeasuring the
42、 comparator bar. Remove the containers from the oven one at a time. Remove other containers only after the specimens in the first container have been measured and returned to the oven. Remove the specimens one at a time from the water and dry their surface with a towel, paying particular attention t
43、o the two metal gauge measuring studs. Record the zero measurements of each specimen immediately after drying, as soon as the specimen is in position. Complete the process of drying and measuring within 15 5 s of removing the specimen from the water. After measurement, leave the specimen on a towel
44、until the remainder of the bars have been measured. Place each set of specimens in separate containers with the 1.0 normal NaOH solution, at 80.0 1.7C (176 3F) to totally immerse the samples. Seal the containers and return them to the oven. 8.4. Undertake subsequent measurement of the specimens peri
45、odically, with at least three intermediate readings, for 14 days after the zero reading, at approximately the same time each day. The measuring procedure is identical to that described in Section 8.3 except that the specimens are returned to their own container after measurement. 9. CALCULATION 9.1.
46、 Calculate the difference between the zero length of the specimen and the length at each period of measurement to the nearest 0.001 percent of the effective gauge length and record as the expansion of the specimen for that period. Report the average expansion of the three specimens of a given cement
47、-aggregate combination to the nearest 0.01 percent as the expansion for the combination for a given period. Note 5When the mean expansion of the test specimens exceeds 0.10 percent at 16 days from casting (14 days from zero reading), it is indicative of potentially deleterious expansion. This value
48、has been determined from tests of aggregate with known field performance in concrete. When the mean expansion of the test specimens is less than 0.10 percent at 16 days after casting, it is indicative of innocuous behavior (Hooton and Rogers, 1989). 10. REPORT 10.1. The report shall include the foll
49、owing: 10.1.1. The type and source of aggregate; 10.1.2. The type and source of portland cement; 10.1.3. The average length change in percent at each reading of the specimens; 10.1.4. Any relevant information concerning the preparation of aggregates, including the grading of the aggregate when it differs from that given in Section 7.2; 10.1.5. Any significant features revealed by examination of the specimens during and after test; 10.1.6. The amount of mixing water expressed as mass percent
