1、Standard Method of Test for Coated Dowel Bars AASHTO Designation: T 253-02 (2016) Release: Group 2 (June 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4g T 253-1 AASHTO Standard Method of Test for Coated Do
2、wel Bars AASHTO Designation: T 253-02 (2016) Release: Group 2 (June 2016) 1. SCOPE 1.1. These methods are designed to test the qualifications of the organic coating of corrosion-resistant dowel bars to withstand the effects of weathering, deicing chemicals, and the abrading and loading stresses expe
3、rienced in field joints. 1.2. The units of measure to be used shall be either SI units or inch-pound units (shown in parentheses in this standard) depending on the units used in the applicable material specification. 1.3. The values stated in SI units are to be regarded as the standard. 2. REFERENCE
4、D DOCUMENTS 2.1. AASHTO Standards: R 39, Making and Curing Concrete Test Specimens in the Laboratory T 106M/T 106, Compressive Strength of Hydraulic Cement Mortar (Using 50-mm or 2-in. Cube Specimens) 2.2. ASTM Standards: D1474/D1474M, Standard Test Methods for Indentation Hardness of Organic Coatin
5、gs G8, Standard Test Methods for Cathodic Disbonding of Pipeline Coatings G12, Standard Test Method for Nondestructive Measurement of Film Thickness of Pipeline Coatings on Steel (withdrawn 2013) G14, Standard Test Method for Impact Resistance of Pipeline Coatings (Falling Weight Test) G20, Standard
6、 Test Method for Chemical Resistance of Pipeline Coatings 3. MATERIALS AND APPARATUS 3.1. The concrete design and constituents shall comply with the procedure and specification stated by the purchasing or specifying agency. 3.2. Suitable containers, molds, and miscellaneous concrete mixing equipment
7、 necessary for mixing and casting the simulated doweled joints for load, pullout, and corrosion tests to meet condition stated in R 39. 3.3. An abradometer capable of operating at 60 to 70 double strokes per minute using 100-mm- (4-in.) long strokes. 2016 by the American Association of State Highway
8、 and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g T 253-2 AASHTO 3.4. Universal test machine capable of operating accurately in the 0- to 45-kN (10,000 lbf) ranges and capable of controlled stress and strain rate loading. 3.5. Suitable hold-down d
9、evices for positioning and holding the casting in place without rotation during the flexure tests. 3.6. Freezethaw equipment of sufficient capacity to handle the pullout and corrosionabrasion test specimens. 3.7. Sufficient quantities of chemical to maintain solution for corrosion tests. 4. PREPARAT
10、ION OF SAMPLES 4.1. The coated dowels for deflection tests may be in support baskets or loose. The coated dowels for the remainder of tests shall be loose. 4.2. Type Acoated dowels shall be cast without additional coating of any kind. Type Bcoated dowels shall be covered before casting with the debo
11、nding agent specified by the coating manufacturer. 4.3. The prepared dowels shall be cast in the appropriate molds specified for the various tests. 5. LOAD-DEFLECTION TEST PROCEDURE 5.1. Six dowels with basket assemblies, if any, will be utilized in three load-deflection tests. The test will be cond
12、ucted in accordance with the following procedures: 5.2. Two dowels with basket assemblies, or without basket assemblies in case of loose dowels, shall be cast into each concrete test specimen in a manner to simulate two 305-mm- (12-in.) long highway contraction joints. (See Figure 1.) The contractio
13、n joints are formed by dividing the mold into three sections with two-piece plates 9.5 mm (3/8in.) thick. After the mold has been filled, the concrete shall be consolidated by vibration. 5.3. The concrete test specimens shall be made and cured in accordance with R 39. The specimens shall be removed
14、from the molds after a 24-h curing period and shall be further moist-cured for a total of 14 days. 5.4. On completion of curing, the simulated joint shall be placed in a testing machine and loaded as illustrated in Figure 1. The end sections will be provided with suitable hold-down devices to preven
15、t rotation. The load shall be applied at the rate of 8.9 kN/min (2000 lbf/min) until a load of 17.8 kN (4000 lbf) is obtained. The relative deflection between the loaded center section and the supported stationary ends will be measured under the 17.8-kN (4000-lbf) maximum load. Record maximum relati
16、ve deflection under load. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g T 253-3 AASHTO 304.89.5 JointPavementDepth9.5 JointMax AllowableDeflection = 0.25across JointMax AllowableDeflection = 0.2
17、5across JointUniform LoadReaction ReactionNote: All dimensions shown in millimeters unless otherwise noted. Figure 1Load-Deflection Test Specimen and Diagram 6. PULLOUT TEST PROCEDURE 6.1. Three dowels shall be tested in accordance with the following procedures: 6.2. For one half of its length, each
18、 dowel shall be cast into a 152.4-mm (6-in.) diameter concrete cylinder. Care shall be taken to assure that the dowels are on the centerline axis of the concrete cylinder. The concrete shall be consolidated by vibration. 6.3. Cure the molded specimens in accordance with R 39. Remove the molds from t
19、he specimens after the first 24 h of a 48-h moist-curing period. 6.4. After 48-h curing 2 h, place the concrete cylinder in the testing machine and apply a tensile load parallel to the axis of the dowel. Record the maximum pullout tensile load for the first 12.7 mm (0.5 in.) of movement for each of
20、the three test specimens. The testing machine shall be adjusted to a free-running speed of 0.76 mm/min (0.030 in./min) prior to performing this test and this setting shall be maintained during the test. 6.5. After the first 12.7 mm (0.5 in.) of movement of the dowels, the test specimens will be furt
21、her cured as before for an additional 12 days. Then the test specimens will be placed in a 10 mass percent sodium chloride solution in such a manner as to inundate half of the cross-sectional perimeter of the dowels. The sodium chloride solution will be maintained at this level and 2016 by the Ameri
22、can Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g T 253-4 AASHTO once a week it will be replaced by a fresh solution. The partially submerged specimens will be subjected to 50 cycles of freezing and thawing consisti
23、ng of freezing in air for 16 h at a temperature of 28.9 1.7C (20 3F) and thawing in air for 8 h at a temperature of 22.8 1.7C (73 3F). 6.6. On completion of the freezethaw cycling, the test specimens will again be placed in the testing machine and the pullout load redetermined by pulling out the dow
24、els an additional 12.7 mm (0.5 in.) at the rate specified in Section 6.4. Again record the maximum tensile load for each of the specimens. 6.7. After the total 25.4-mm (1-in.) movement of the dowel, remove the concrete by breaking it away from the dowel. The dowel and the concretedowel interface wil
25、l be examined for corrosion, tearing, and perforation. 7. CORROSIONABRASION TEST PROCEDURE 7.1. Three dowel bars shall be subjected to corrosionabrasion testing in accordance with the following procedures: 7.2. Abrasion resistance of the dowels will be determined by the use of an abradometer. The ab
26、radometer is operated at 60 to 70 double strokes per minute using a 100-mm (4-in.) long stroke. The abrading block is a 4-in. long mortar block made of portland cement and Ottawa sand (T 106M/T 106) cast to fit over about one third of the perimeter of the test dowel. The test load is the 2500-g mass
27、 of the abrading assembly and block. Each dowel will be tested for a total of 10,000 double strokes (from the starting point to the far end and returning to the starting point is considered one double stroke). 7.3. On completion of the abrading, the dowels will be examined for wear, perforation, and
28、 wrinkling. 7.4. After completion of testing in Section 7.3, determine loss of thickness due to abrasion by ASTM G12. A minimum of five readings shall be taken in both the abraded and unabraded portions of the dowel. The average of the five readings shall determine the respective thickness. 7.5. The
29、 abraded dowels will be placed in a 10 mass percent sodium chloride solution so as to inundate half of the cross-section perimeter of the abraded area and expose the upper half to the atmosphere. The sodium chloride solution will be maintained at this level and once a week it will be replaced by a f
30、resh solution. A sufficient length of the coated dowel will be subjected to the test so that not less than 50 mm (2 in.) of unabraded coating is tested at each end of the abraded area. The partially submerged specimens will be subjected to 50 cycles of freezing and thawing as specified in Section 6.
31、5. 7.6. After the 50 cycles of freezing and thawing, the dowel will be removed and thoroughly examined for corrosion under five-power magnification. 8. CHEMICAL RESISTANCE TEST PROCEDURE 8.1. Three dowel bars will be subjected to chemical resistance testing in accordance with the following procedure
32、: 8.2. Sample bars will be tested in the manner described in ASTM G20, by immersion for 45 days in each of the following: distilled water, an aqueous solution of 3 molar CaCl2, an aqueous solution of 3 molar NaOH, and a solution saturated with Ca(OH)2at a temperature of 23.9 1.7C (75 3F). 2016 by th
33、e American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g T 253-5 AASHTO 9. CATHODIC DISBONDING TEST PROCEDURE 9.1. Two dowel bars shall be tested to determine their resistance to cathodic disbonding in the following
34、 manner: 9.2. The test procedure shall be Method A of ASTM G8, except: (1) the cathode and anode shall be dowel bars coated with the same material, (2) the electrolyte shall be an aqueous solution of 7 percent mass NaCl, (3) a potential of 2 V shall be applied, and (4) no intentional holes shall be
35、cut except for a single 6.4-mm (1/4-in.) diameter hole made in the middle of the immersed length in both the anode and the cathode. The test period duration shall be 30 days. 10. COATING HARDNESS TEST PROCEDURE 10.1. Three dowel bars shall be tested in the following manner to determine the hardness
36、of the plastic coating: 10.2. The hardness of the coating shall be determined using the method of ASTM D1474/D1474M, using a 100-g (0.22-lb) mass. 11. COATING IMPACT RESISTANCE TEST PROCEDURE 11.1. Three dowel bars shall be tested in the following manner to determine the resistance of the coating to
37、 impact: 11.2. The coating shall be subjected to an impact force of 9 J (80 in.-lb) with a 1.8-kg (4-lb) tup at 23.9 1.7C (75 3F) according to the procedure of ASTM G14. 12. REPORT 12.1. The report shall show all temperature, load, and miscellaneous data pertinent to the test conditions, including t
38、he following: 12.1.1. Maximum relative deflection under a 17.8-kN (4000-lbf) load for each specimen, procedure in Section 5, Load-Deflection Test Procedure. 12.1.2. Maximum kilonewton (lbf) load for pullout of each specimen after 48-h curing period and after the subsequent 50-cycle freezethaw proced
39、ure in Section 6, Pullout Test Procedure. 12.1.3. Original thickness of coating and abraded thickness, procedure in Section 7, CorrosionAbrasion Test Procedure. 12.1.4. Observation of the condition of each specimen after completion of the freezethaw cycling of procedure in Section 6, Pullout Test an
40、d procedure in Section 7, CorrosionAbrasion Test Procedure. 12.1.5. Coating condition after completion of procedure in Section 8, Chemical Resistance Test Procedure. 12.1.6. Evidence, if any, of hydrogen evolution, corrosion products, undercutting or other film failure resulting from procedure in Se
41、ction 9, Cathodic Disbonding Test Procedure. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g T 253-6 AASHTO 12.1.7. Coating hardness as determined by procedure in Section 10, Coating Hardness Test Procedure. 12.1.8. Nature of the coating failure, if any, when subjected to procedure in Section 11, Coating Impact Resistance Test Procedure.
