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13 Table 2-3. AASHTO M320 properties for the neat binders used in NCHRP 9-36. Condition Test Method CITGO AAC-1 AAD-2 AAF-1 AAM-1 ABL-1 ABM-2 58-28 Unaged Viscosity at 135°C, Pa·s AASHTO T316 0.23 0.18 0.26 0.34 0.55 0.42 0.19 Temperature for G*/sin of 1.00 kPa at 10 AASHTO T315 59.7 56.5 57.0 65.4 67.7 68.5 62.7 rad/s, °C RTFO Aged Mass Change, % AASHTO T240 -0.358 -0.058 -1.058 -0.008 +0.122 -0.654 -0.348 Residue Temperature for G*/sin of 2.20 kPa at 10 AASHTO T315 59.8 56.3 65.6 67.0 68.0 69.5 60.7 rad/s, °C Temperature for G*sin of 5000 kPa at 10 AASHTO T315 13.0 17.7 11.9 27.2 19.0 17.5 25.2 PAV Aged rad/s, °C Residue Temperature for Creep Stiffness of 300 MPa, AASHTO T313 -20.1 -18.1 -23.7 -12.2 -16.6 -19.6 -6.0 at 60 s, °C Temperature for m-value of 0.300 at 60 s, °C AASHTO T313 -23.1 -16.7 -24.6 -9.8 -11.3 -19.9 -10.2 M320 Grade 58-28 52-22 52-28 64-16 64-16 64-28 58-16 MGRF, and RTFOT. The verification study was the last study The modified binders were selected to represent a range of conducted in NCHRP Project 9-36 and provided the basis for binder grades, modifiers, and modification processes. These making the final recommendation with respect to a replace- included an airblown binder, two binders modified with ment for the RTFOT. Findings from the verification study are SBS, one binder modified with Elvaloy, one binder modified presented in Chapter 3. The verification study is documented with LDPE, and one binder modified with ethyl vinyl acetate in Appendix E (available on the TRB website). (EVA). All of the modified binders except the EVA binder were obtained from commercial sources. A commercial source 2.7 Materials supplying EVA-modified binders for paving applications could not be identified; therefore, the EVA binder was pro- 2.7.1 Binders duced in the laboratory of Advanced Asphalt Technologies, NCHRP Project 9-36 used 13 different asphalt binders: LLC, by modifying a PG 64-22 binder from the Paulsboro, seven neat binders and six modified binders. The binders New Jersey, refinery of Citgo with 7 percent by weight Repsol were selected to provide a wide range of physical and chemi- Quimica PA-420. The Repsol Quimica PA-420 was obtained cal properties and modification processes. Tables 2-3 and 2-4 from Momentum Technologies, Inc. The airblown binder present AASHTO M320 properties for the binders used in graded as a PG 76-16. It was obtained from Western Refin- Project 9-36. ing's El Paso, Texas, refinery. Citgoflex is an SBS-modified The neat binders included a PG 58-28 from the Paulsboro, binder produced in several grades by Citgo. The Citgoflex New Jersey, refinery of the Citgo Asphalt Refining Company binder used in NCHRP Project 9-36 was a PG 82-22 grade (Citgo) and six binders (AAC-1, AAD-2, AAF-1, AAM-1, and was obtained from Citgo's Paulsboro, New Jersey, refin- ABL-1, and ABM-2) from the FHWA Materials Reference ery. The second SBS-modified binder was that included in the Library (MRL). Detailed information on the chemical com- FHWA Pooled Fund Study TPF-5(019), Full Scale Accelerated position of the MRL binders is contained elsewhere (7). Performance Testing for Superpave and Structural Validation. Table 2-4. AASHTO M320 properties for the modified binders used in NCHRP 9-36. Condition Test Method Airblown Citgoflex ALF Elvaloy Novophalt EVA Modifier Airblown SBS SBS Elvaloy LDPE EVA Unaged Viscosity at 135°C, Pa·s AASHTO T316 0.79 2.94 1.20 0.65 1.72 2.07 Temperature for G*/sin of 1.00 kPa at AASHTO T315 77.3 88.5 73.6 67.4 77.9 82.9 10 rad/s, °C RTFO Aged Mass Change, % AASHTO T240 +0.031 -0.196 -0.207 -0.173 -0.132 -0.132 Residue Temperature for G*/sin of 2.20 kPa at AASHTO T315 80.3 85.2 75.4 69.9 78.9 81.0 10 rad/s, °C Temperature for G*sin of 5000 kPa at AASHTO T315 22.2 23.6 5.8 16.0 22.0 16.5 PAV Aged 10 rad/s, °C Residue Temperature for Creep Stiffness of 300 AASHTO T313 -17.2 -14.5 -29.8 -19.1 -14.2 -15.4 MPa, at 60 s, °C Temperature for m-value of 0.300 at 60 AASHTO T313 -8.1 -14.1 -27.1 -18.6 -11.1 -12.9 s, °C M320 Grade 76-16 82-22 70-34 64-28 76-16 76 22
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14 100 90 80 70 60 50 40 30 20 10 0 0.075 0.3 0.6 1.18 2.36 4.75 9.5 12.5 0.15 SIEVE SIZE, mm Figure 2-5. Gradation of the 9.5-mm limestone mixture. This binder graded as a PG 70-34. The Elvaloy binder was pro- binder. Pertinent volumetric properties at the optimum vided by Mathy Construction. It graded as a PG 64-28. Finally, binder content are summarized in Table 2-5. For the oven-aged the Novophalt binder was provided by Advanced Asphalt Tech- mixture experiment, mixtures were produced using the six nologies, LLC. This binder contains recycled LDPE and graded MRL binders and the six modified binders from Tables 2-3 as a PG 76-16. and 2-4. The same binder content of 5.5 percent was used in The Citgo PG 58-28 was used in the selection study, the VCS each of the 12 mixtures produced. study, and the SAFT optimization study. MRL binders AAD, AAM, and ABL2 were used in the VCS study and the SAFT Table 2-5. Volumetric properties for the optimization study. The Citgoflex and Novophalt binders also 9.5-mm limestone mixture. were used in the selection study. All of the MRL binders and all of the modified binders were used in the verification study. Property Sieve Size, mm Value 12.5 100 9.5 94 4.75 50 2.7.2 Aggregate 2.36 32 Gradation 1.18 20 Because research completed during SHRP showed a rela- 0.600 13 tively minor effect of aggregate type on short-term mixture 0.300 9 0.150 6 aging (4), only one aggregate and one gradation were used in 0.075 5.1 the oven-aged mixture experiment of the verification study. Asphalt Content, % 5.5 The aggregate was a limestone from Frazier Quarry, Incorpo- Ndesign 100 VMA, % 15.8 rated's North Quarry in Harrisonburg, Virginia. This aggre- VFA, % 72.6 gate was used extensively in various mixture volumetric studies Dust/Binder Ratio (Weight Basis) 1.0 completed in NCHRP Projects 9-25 and 9-31 (8). Figure 2-5 Fine Aggregate Angularity, % 46.0 Coarse Aggregate Angularity, % 100/100 shows the gradation of the coarse graded 9.5-mm nominal Flat and Elongated Particles, % 0.8 maximum aggregate size mixture that was used. The optimum Sand Equivalent 75 binder content for this mixture was selected using a PG 64-22 Surface Area, m2/kg 4.40