1、TS-4e TP 88-1 AASHTO Standard Method of Test for Evaluation of the Low-Temperature Tensile Property of Bituminous Sealants by Direct Tension Test AASHTO Designation: TP 88-10 (2013) 1. SCOPE 1.1. This test method applies to bituminous sealants used in the construction and maintenance of roadways. 1.
2、2. The test method is used to determine the extensibility and strain energy density (SED) of sealants at low temperature. It can be used with unaged material or with material aged using TP 86. The test apparatus is designed for testing within the temperature range from 4 to 40C. 1.3. This standard c
3、overs the determination of extensibility and percent modulus decay in bituminous sealants with the use of direct tension testing and by applying the tensile stressstrain test. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: T 314, Determining the Fracture Properties of Asphalt Binder in Direct Tensio
4、n (DT) TP 86, Accelerated Aging of Bituminous Sealants and Fillers with a Vacuum Oven TP 87, Measure Low-Temperature Flexural Creep Stiffness of Bituminous Sealants and Fillers by Bending Beam Rheometer (BBR) TP 89, Measuring Adhesion of Hot-Poured Crack Sealant Using Direct Adhesion Tester 2.2. AST
5、M Standards: D 5167, Standard Practice for Melting of Hot-Applied Joint and Crack Sealant and Filler for Evaluation D 6373, Standard Specification for Performance Graded Asphalt Binder E 1, Standard Specification for ASTM Liquid-in-Glass Thermometers E 77, Standard Test Method for Inspection and Ver
6、ification of Thermometers 2.3. Sealant Consortium (SC) Standards:1 SC-1, Guidelines for Graded Bituminous Sealants SC-2, Test Method for Measuring Apparent Viscosity of Hot-Poured Crack Sealant Using Brookfield Rotational Viscometer RV Series Instrument SC-3, Method for the Accelerated Aging of Bitu
7、minous Sealants SC-4, Sealant Flow and Deformation SC-5, Method to Measure Low-Temperature Sealant Flexural Creep Stiffness at Low Temperature by Bending Beam Rheometer SC-6, Method to Evaluate Sealant Extensibility at Low Temperature by Direct Tension Test 2013 by the American Association of State
8、Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4e TP 88-2 AASHTO SC-7, Test Method for Measuring Adhesion of Hot-Poured Crack Sealant Using Direct Adhesion Tester 2.4. Other Documents: Dowling, N. E. Mechanical Behavior of Materials, Second
9、Edition. Prentice Hall, Upper Saddle River, NJ, 1999. 3. TERMINOLOGY 3.1. bituminous sealantshot-poured modified asphaltic materials used in pavement cracks and joints. 3.2. effective gauge lengthelongation of a standard dog bone-shaped test specimen due to an applied axial load P is equivalent to t
10、hat of a simple rectangular specimen with the same cross-sectional dimensions of the restricted section. Effective gauge length, Le, is defined as the length of the simple rectangular specimen and has been determined to be 20.3 mm. 3.3. tensile stresstensile load divided by the true area of cross se
11、ction of the specimen. 3.4. tensile strainchange in the effective gauge length by the application of tensile load divided by the original unloaded effective gauge length. 3.5. brittle materialthe stressstrain curve is linear up to fracture at about 1 to 2 percent elongation. 3.6. brittle-ductile mat
12、erialthe stressstrain curve is curvilinear and the stress is gradually reduced after the peak point. The failure happens by gradually breaking the molecular bond within the material. 3.7. ductile materialthe material does not rupture in the direct tension test but elongates due to high strain. 3.8.
13、rubbery behaviormaterials that exhibit rubbery behavior can be stretched to extreme elongation without rupture. 3.9. percent modulus decaythe percentage modulus deduction after 10 s of loading. 4. SUMMARY OF PRACTICE 4.1. This practice contains the procedure to measure the extensibility and the stra
14、in energy density of a bituminous sealant or filler using a direct tension test (DTT). The material is bonded between two end tabs made of poly(methyl methacrylate) (PMMA) and subjected to a constant strain rate at a specific temperature. 4.2. The test method is developed to select the bituminous se
15、alant at temperatures where they exhibit rubbery behavior. 4.3. A linear variable differential transformer (LVDT) is used to measure the elongation of the test specimen as it is pulled in tension at a constant strain rate of 6 percent/min (1.2 mm/min). A load cell is used to monitor the load during
16、the test. The stress and strain at the point of rupture or peak load are reported. 2013 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4e TP 88-3 AASHTO 5. SIGNIFICANCE AND USE 5.1. This test is intended
17、for bituminous sealants applied to roadway joints and cracks. 5.2. The test temperature is determined to be the lowest temperature experienced by the pavement surface in the geographical area for which the sealant is intended. 5.3. The sealant extensibility is a parameter of the capacity of the seal
18、ant to sustain large deformations due to crack expansion at low temperature without fracture. 5.4. The percent modulus decay is an indication of how fast the sealant can release the imposed loading. A higher percentage decay represents that the sealant can relax the load faster. 5.5. This method is
19、intended for aged sealants, which could become stiffer or softer with age. 6. APPARATUS 6.1. Direct Tension Test (DTT) DeviceThe DTT system consists of two metal grips to hold the specimen, an environment chamber, a loading device, and a control and data acquisition system. The instrument must meet
20、the requirements stated in T 314. 6.2. Specimen End Tabs and Gripping SystemEnd tabs made from PMMA having dimensions as described in Figure 1 that shall be bonded to both ends of the test specimen to transfer the tensile load to the sealant. The manufacturing requirement of the end tabs and the gri
21、pping system shall meet the requirement in T 314. 6.3. Chiller and Test ChamberA calibrated circulated temperature control system shall have a temperature range from 4 to 40C. The insulated test chamber shall be capable of maintaining a temperature of 0.1C. 6.4. Specimen MoldsThe specimen molds shou
22、ld be made from aluminum. Molds shall have dimensions as specified in Figure 1. A silicon-based release agent, as described later in Section 7.2, shall be used to prevent the sealant from adhering to the aluminum molds. 6.5. Laboratory OvensTwo forced-air convection ovens capable of producing, reach
23、ing, and maintaining a temperature of 200 0.5C for heating the sealant and molds. 2013 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4e TP 88-4 AASHTO Dia.15.0025.0038.0050.0020.0227.003.00 5.007.0044.00
24、100.0424.00100.0054.001.6012.00B6.00100.003.93R7.5044.6524.00Dia. 10.00100.0062.0038.00 24.003.00Mold BaseMold HalfEnd Insert16.50Note: Dimensions are in mm. Figure 1Dimensions for DTT, End Insert, and Mold 7. REAGENTS AND MATERIALS 7.1. Fluid for Test ChamberA fluid that is not absorbed by or does
25、not affect the properties of the crack sealant being tested. The bath fluid shall be optically clear at the test temperature. Ethyl alcohol is suggested to use as a fluid for temperature control. The aqueous mixture of potassium 2013 by the American Association of State Highway and Transportation Of
26、ficials.All rights reserved. Duplication is a violation of applicable law.TS-4e TP 88-5 AASHTO acetate and deionized water used in T 314 has been found to form a turbid solution at a temperature of 40C. 7.2. Release AgentA proper release agent to prevent the crack sealant from sticking to the mold.
27、A silicon-based release agent is recommended. 7.3. SolventA solvent can properly clean the molds, end tabs, and plates. The parts cleaned by the solvent shall be submerged in the ethyl alcohol prior to use. This ensures the proper bond between sealant and end tabs. 7.4. Cleaning ClothsCloths for wip
28、ing molds, end tabs, and plates. 8. HAZARDS 8.1. Standard laboratory caution should be used in handling hot sealant in accordance to ASTM D 5167, and required safety procedures should be followed when chemical agents are used. 9. VERIFICATION AND CALIBRATION 9.1. DTTFollow the procedure as stated in
29、 T 314. 9.2. Oven and FreezerCalibrate the temperature with a thermometer that meets the requirements of ASTM E 1. The thermometer calibration can be verified according to ASTM E 77. 10. SAMPLES PREPARATION 10.1. Sample and prepare the sealant according to ASTM D 5167. See Note 1. Note 1It is advant
30、ageous to sample about 500 g of the sealant and sequentially pour specimens for all the tests, including the aging test (TP 86), the low-temperature tests (TP 87 and TP 88), and the adhesion test (TP 89). 10.2. Anneal the sealant from which the test specimen is obtained by heating for 30 min. After
31、15 min, place the sealant in the oven, remove the sealant from the oven shortly, and stir the sealant by spatula to prevent segregation. 10.3. Follow the procedure in Sections 9.2 to 9.6 of T 314 with the following modification. See Notes 2 and 3. Note 2If a spray-type silicon-based release agent is
32、 used, start from one side of the mold and slowly move toward the other side. Only one spray should be applied to the mold. Note 3Place the molds and end tab assembly on top of a ceramic tile heated to 50C lower than the sealant pouring temperature. The ceramic tile should be placed in the preheated
33、 oven for 15 min. 11. CONDITIONING 11.1. Follow the procedure as stated in T 314. 12. PROCEDURE 12.1. Bring the DTT chamber to the test temperature (see Note 4). 2013 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicab
34、le law.TS-4e TP 88-6 AASHTO Note 4Select test temperatures in accordance with the applicable material specification (e.g., SC-1 or ASTM D 6373). 12.2. Prepare four test specimens according to Section 10. 12.3. Follow the procedure in Sections 12.2 to 12.3 of T 314 with the modifications in Notes 5 a
35、nd 6. Note 5Adjust the load frame to allow 20-mm traveling distance; then place the specimen on the loading pin. Remove the slack between the specimen and the loading pins. Note 6Manually adjust the thumb wheel on the control box to apply tension in the specimen until a load of 1 0.5 N is shown on t
36、he screen. Then calibrate the stroke and load back to zero. 12.4. Set the strain rate to 6 percent/min (1.2 mm/min) and start the test. 12.5. After the specimen fractures, degradation is observed or maximum traveling distance is reached (whichever comes first), stop the test and remove the specimen
37、from the loading frame. 12.6. The extensibility is identified as follows: 12.6.1. When the specimen fractures (breaks into two pieces), the extensibility is easily identified as the strain at peak load (maximum stress). 12.6.2. When the specimen does not fracture, but reaches a maximum stress and th
38、en flows without fracture, the extensibility is recorded as the strain corresponding to the maximum stress. 12.6.3. When the specimen does not fracture or load reduction is not observed, the extensibility is recorded as the strain at the end of the traveling distance. 12.7. Repeat steps in Sections
39、12.3 to 12.6 for the remaining three specimens. 12.8. After testing is complete, discard the bituminous portions of the spent specimens and clean the end tabs by soaking them in solvent and wiping with a soft cloth. After wiping the end tabs, use a detergent soap solution to remove any oil film resi
40、due left by the cleaner material. Alternatively, use a degreasing spray cleaner. Clean the end tabs thoroughly. A grease film on the sealant bonding area can create a weak bond causing bond failures. 13. CALCULATIONS 13.1. For each test result, calculate the engineering stressstrain: 0ffPA (1) ffeLL
41、 (2) where: f= peak stress; Pf= measured load at peak; A0= original cross-sectional area (= 18 mm2); f= measured strain at peak load; 2013 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4e TP 88-7 AASHTO
42、Lf= measured elongation at failure (L); and Le= effective gauge length (= 20.3 mm). 13.2. For each test result, calculate the true stressstrain: 0fLL (3) 0tfiPPeAA (4) where: = true strain; Lf= measured elongation at failure (L); and L0= effective gauge length (= 20.3 mm); = true stress; Pf= measure
43、d load at peak; = strain rate; and A0= original cross-sectional area (= 18 mm2). 13.3. The extensibility is identified as . 13.4. Select the three test results that give the best coefficient of variation of the extensibility. Calculate the mean and standard deviation for SED from the selected three
44、test results. 13.5. Calculate the percent modulus decay: 13.5.1. From the Boltzman superposition principle, the stressstrain relationship for a viscoelastic material can be expressed as Equation 5. 0tdttEtt dtdt(5) where: (t) = stress history; E(t) = the relaxation modulus; and (t) = strain history.
45、 13.5.2. The Prony series (generalized Kelvin model) is used to describe the viscoelastic behavior of hot-poured crack sealants as presented in Equation 6. /011iKtiiEt E E e (6) where: E(t) = the relaxation modulus at time t; Ei= material constants; and i= retardation times. 2013 by the American Ass
46、ociation of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4e TP 88-8 AASHTO 13.5.3. Substituting Equation 6 into Equation 5, the expression of the stress becomes: 001itttNiidttEt E e dtdt (7) 13.5.4. In the DTT, the sealant is subject
47、ed to a constant strain rate beginning at time zero, 0 for 0 for 0tttt, with as the strain rate. The above convolution integral can then be solved as follows: 01itNiiitEt ERt e (8) 13.5.5. The equation is used to fit the experimental data by means of the nonlinear least squares (NLS) technique to ob
48、tain the material constants E0, Ei, and i. 13.6. The percent modulus reduction after 10 s of loading is calculated as follows: 1010 01000EEME (9) 14. REPORT 14.1. Report the following information about the material: 14.1.1. Sealant name and supplier, 14.1.2. Lot number, 14.1.3. Date received, and 14
49、.1.4. Date sampled according to ASTM D 5167. 14.2. Report the following information about the test procedure: 14.2.1. Date and time of test, 14.2.2. Test temperature, 14.2.3. Rate of elongation, 14.2.4. Average extensibility, 14.2.5. Average SED and their standard deviation, 14.2.6. Peak load, and 14.2.7. Type of fracture (fracture or no fr
