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52 residues exhibited the highest rotational viscosity, whereas To establish sound correlations between the rheologi- CRS-1 residues had the lowest rotational viscosity (see Fig- cal properties of emulsified tack coat materials and ISS, ure 55c). Furthermore, the ranking of the softening point test trackless and CRS-1 were tested using the dynamic shear results was similar to the ranking of the results of the penetra- rheo meter at temperatures ranging from -10 to 60C with tion test, absolute viscosity test, and rotational viscosity test a 10C interval. Testing was conducted using an AR2000 (see Figure 55d). The ranking of the materials from hardest rheo meter in the dynamic shear mode. Two sample sizes to softest was trackless residual, the SS-1h residual, PG 64-22 were used, depending on the testing temperature: a sample binder, and the CRS-1 residual. with a 25-mm diameter and 1-mm thickness was used at high temperatures (from 40 to 60C), and 8-mm diam- eter and 2-mm thickness was used at low and intermediate 4.3.1Superpave Grading of Emulsified temperatures (from -10 to 30C). Figure 56 presents the Tack Coats dynamic shear rheometer (DSR) test results for both tack Emulsified tack coats are composed of three basic ingre- coat materials. As shown in this figure, the complex shear dients: asphalt, water, and emulsifying agent. The asphalt modulus (G*) increased linearly for both tack coat materi- binder residues were obtained according to AASHTO D als on a semi-logarithmic scale. As expected, the trackless 244, Residue by Evaporation. Table 16 presents the results materials produced higher G* values than did CRS-1. of tests performed on these residues. It is noted that the residues of CRS-1 and SS-1h emulsions were graded as PG 4.3.2Relationship Between LTCQT 58-22 and 70-22, respectively. The trackless material, how- Test Results and Tack Coat ever, failed the intermediate- and low-temperature perfor- Rheological Properties mance criteria. This response was expected since trackless is a polymer-modified emulsion with a hard base asphalt The LTCQT test was performed on four tack coat materi- cement. als: trackless, CRS-1, SS-1h, and PG 64-22. Based on these Table 16. Rheological test results of emulsified tack coat residues. Aging AASHTO SS-1h SS-1 CRS-1 Trackless Test Property Spec. PG 64-22 Status Method residual residual residual residual Rotational viscosity, Pa.s 135C T 316 3.0 0.5 0.6 0.3 0.3 2.5 1.0+ 1.86 (64C) 15.4 (52C) 2.5 (52C) 3.0 (52C) 19.0 (64C) Dynamic shear 6.5 (58C) 1.3 (58C) 1.3 (58C) 7.6 (70C) Original 10 rad/s T 315 2.9 (64C) 0.8 (64C) 0.6 (64C) 3.4 (76C) Binder G*/sin , kPa 1.4 (70C) 1.5 (82C) 0.7 (76C) 0.7 (88C) Softening Point 53C 42.5C 76C Mass change, % T 240 1.0 0.009 0.1 0.1 0.1 NA Rolling 2.20+ 4.4 (64C) 2.8 (70C) 2.2 (58C) 2.9 (58C) 16.9 (70C) Thin- Film Dynamic shear 7.4 (76C) Oven T 315 10 rad/s, G*/sin , kPa 3.4 (82C) Residue 1.5 (88C) 3,177 3,239 2,411 3,306 10,907 Dynamic shear, 10 rad/s , G*sin , kPa T 315 5000 (25C) (25C) (19C) (19C) (25C) 210 165.0 84.5 86.8 300 (12C) ( 12C) (12C) (12C) Pressure Bending Beam Creep stiffness, S, MPa 60s T 313 * 174 187.0 Aging (18C) (18C) Vessel 0.285 0.320 0.42 0.340 Residue 0.300+ (12C) (12C) (12C) (12C) 100C Bending Beam Creep stiffness, m-value 60s T 313 * 0.34 0.310 (18C) (18C) 1.1 1.1 Direct tension 1.0 mm/min, % T 314 1.0+ 1.2 (12C) 1.6 (12C) * (18C) (18C) PG Grading PG 64-22 PG 70-22 PG 58-28 PG 58-28 -- *Sample was brittle and failed.