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From page 5... ... However, for the 19-mm NMAS limestone SMA mix, 4 percent air voids could be achieved with 5.7 percent asphalt content, which did not meet the minimum asphalt content requirement in accordance with the "Standard Practice for Designing SMA," AASHTO PP44-01. Therefore, the minimum asphalt content of 6.0 percent was chosen, which resulted in 3.7 percent air voids at the design number of gyrations. Read the entire page →
From page 6... ... 6 4.3 EVALUATION OF EFFECT OF t/NMAS ON DENSITY USING VIBRATORY COMPACTOR After obtaining the results for the Superpave gyratory compactor, it was concluded that more tests needed to be conducted to better simulate compaction in the field. The air voids determined from the vacuum seal device were utilized in the analysis. Read the entire page →
From page 7... ... Figure 2. Relationship between air voids for TRZ mixes. Read the entire page →
From page 8... ... After compaction, the bulk specific gravity was measured and the data were analyzed to provide recommendations concerning the minimum t/NMAS. To determine the minimum t/NMAS, relationships between average air voids for the two types of aggregates and t/NMAS were plotted for each NMAS, compaction time, and gradation, as shown in Figures 11 through 17. Read the entire page →
From page 9... ... Figure 6. Relationships between air voids and t/NMAS for 19.0-mm Superpave mixes. Read the entire page →
From page 10... ... Figure 9. Relationships between air voids and t/NMAS for 12.5-mm SMA mixes. Read the entire page →
From page 11... ... The rubber tire roller available did not meet desired requirements for weight and tire pressure, and thus the data generated for the rubber tire roller compacted mixture were omitted from the analysis for this section. The breakdown rolling was performed with one pass in the static mode on the mat at a temperature of about 300°F. Read the entire page →
From page 12... ... A review of the data indicated that a polynomial function provided the best fit line. The best-fit line indicates that the air voids decreased as the t/NMAS increased to a point where additional thickness resulted in increased air voids. Read the entire page →
From page 13... ... The rubber tire roller was a 15-ton HYPAC C560B with a tire pressure of 90 psi. For the side of the mat utilizing only the steel drum roller, the initial rolling was performed with four passes in the vibratory mode at low amplitude and high frequency (3800 vpm) Read the entire page →
From page 14... ... Relationships between air voids and t/NMAS for 19.0-mm SMA mixes. Figure 18. Read the entire page →
From page 15... ... The rubber tire roller was a 15-ton HYPAC C560B with a tire pressure of 90 psi. For the side of the mat utilizing only the steel drum roller, the initial rolling was performed with one pass in the static mode followed by five passes in the vibratory mode operated in low amplitude and high frequency (3800 vpm) Read the entire page →
From page 16... ... This was followed with three passes in the static mode including finish rolling. For the side of the mat that used a rubber tire roller as an intermediate roller, the initial rolling was performed with four passes in the vibratory mode operated at low amplitude and high frequency (3800 vpm) Read the entire page →
From page 17... ... Data in the figure indicate that the lowest in-place air voids (4.7 percent air voids for the steel wheel roller only and 7.5 percent air voids for the steel and rubber tire rollers) occurred at t/NMAS of 4.5 for the steel wheel roller and 4.8 for the rubber and steel wheel rollers. Read the entire page →
From page 18... ... The rubber tire roller was a 15-ton HYPAC C560B with a tire pressure of 90 psi. For the side of the mat utilizing only the steel drum roller, the initial rolling was performed with four passes in the vibratory mode operated at low amplitude and high frequency (3800 vpm) Read the entire page →
From page 19... ... For the side of the mat that used a rubber tire roller as an intermediate roller, the initial rolling was performed with two passes in the vibratory mode operated at low amplitude and high frequency (3800 vpm) Read the entire page →
From page 20... ... Data in the figure indicate that the lowest in-place air voids (5.6 percent air voids for the steel wheel roller only and 7.4 percent air voids for the steel and rubber tire rollers) occurred at t/NMAS of 4.2 for the steel wheel roller and 5.3 for the rubber and steel wheel roller. Read the entire page →
From page 21... ... 2 4.9 2 6.1 3 1.3 3 3.4 0.0 0.0 4 0.0 4 0.8 5 0.8 5 0.0 TABLE 11 Relationship of air voids and t/NMAS for 19.0-mm coarse-graded mix with modified asphalt compacted with steel roller and with steel and rubber tire rollers Description of Mix Increase in Air Voids for t/NMAS=2 Increase in Air Voids for t/NMAS=3 Increase in Air Voids for t/NMAS=4 Increase in Air Voids for t/NMAS=5 Section 1-9.5mm Fine Graded -- Steel Roller 2.5% 1.0% 0.1% 0.1% Section 2-9.5mm Coarse GradedSteel Roller 2.5% 1.0% 0.5% 0.0% Section 2-9.5mm Coarse GradedSteel and Rubber Roller 2.0% 0.5% 0.0% 1.0% Section 3-9.5mm SMA(mod AC) Steel Roller 5.5% 2.0% 0.2% 0.2% Section 3-9.5mm SMA(Mod AC) Read the entire page →
From page 22... ... 4.6 EVALUATION OF EFFECT OF t/NMAS ON PERMEABILITY USING GYRATORY COMPACTOR Specimens were compacted to 7.0 ± 1.0 percent air void content at t/NMAS of 2.0, 3.0, and 4.0. For most mixes, specimens could not achieve the target air voids even when the Read the entire page →
From page 23... ... Relationships between density, t/NMAS, and temperature for Section 2. Difference in Temperature R2 = 0.976 %Lab Density Steel Roller R2 = 0.8335 %Lab Density Steel/Rubber Tire Roller R2 = 0.1864 90.0 91.0 92.0 93.0 94.0 95.0 96.0 97.0 98.0 99.0 100.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 t/NMAS % La b De n si ty -30 -20 -10 0 10 20 30 40 50 D iff er en ce in T em pe ra tu re ,o C Steel Wheel Roller Rubber Tire Roller Difference in Temperature Figure 27. Read the entire page →
From page 24... ... %Lab Density Steel Roller R2 = 0.7736 Different in Temperature @ 20 Min. R2 = 0.8191 95.0 96.0 97.0 98.0 99.0 100.0 101.0 102.0 103.0 104.0 105.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 t/NMAS % La b D en si ty 0 10 20 30 40 50 60 70 D iff er en ce in T em pe ra tu re ,o C Figure 29. Read the entire page →
From page 25... ... 25 Difference in Temperature R2 = 0.6816 Steel/Rubber Tire Roller R2 = 0.4489 93 94 95 96 97 98 99 100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 t/NMAS % La b De ns ity 0 10 20 30 40 50 60 70 D iff er en ce in T em pe ra tu re , ° C Steel/Rubber Tire Roller Difference in Temperature Difference in Temperature R2 = 0.9904 %Lab Density Steel Roller R2 = 0.6529 %Lab Density Steel/Rubber Tire Roller R2 = 0.8092 87.0 88.0 89.0 90.0 91.0 92.0 93.0 94.0 95.0 96.0 97.0 98.0 99.0 100.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 t/NMAS % La b De ns ity -40 -30 -20 -10 0 10 20 30 40 50 60 70 D iff er en ce in Te m pe ra tu re ,° C Steel Roller Steel/Rubber Tire Roller Difference in Temperature Figure 30. Relationships between density, t/NMAS, and temperature for Section 6. Read the entire page →
From page 26... ... 26 y = -0.8216x2 + 7.2531x + 80.848 R2 = 0.2562 86.0 88.0 90.0 92.0 94.0 96.0 98.0 100.0 102.0 104.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 t/NMAS % La b De ns ity Figure 32. Relationships between density and t/NMAS for all sections. Read the entire page →
From page 27... ... The fine graded mixes never exceeded the recommended value even up 9 to 10 percent air voids. 4.9 PART 2 -- EVALUATION OF RELATIONSHIP OF LABORATORY PERMEABILITY, DENSITY AND LIFT THICKNESS OF FIELD COMPACTED CORES The average thickness, the average air void content by the vacuum seal device method, and the average laboratory permeability values were determined for each of the cores obtained from the work under NCHRP Project 9-9 (1) Read the entire page →
From page 28... ... At air void contents above 8 percent, the permeability begins to increase rapidly with a small increase in in-place air void content. At 8 percent air voids, the fine-graded 19.0-mm NMAS mix has a permeability value of 16 × 10−5 cm/sec. Read the entire page →
From page 29... ... Each of the prepared samples was tested to determine bulk specific gravity by four different test methods: water displacement, vacuum-sealing, gamma ray, and dimensional. y = 0.0437e0.7362x R2 = 0.5923 0 20 40 60 80 100 120 140 0.0 2.0 4.0 6.0 8.0 10.0 12.0 In-place Air Voids (Corelok) Read the entire page →
From page 30... ... Analysis of both the Superpave and SMA data indicated that the four methods of measuring bulk specific gravity significantly affected resulting air voids. For both mix types, the vacuum-sealing and gamma ray methods provided similar air voids; however, the dimensional method provided significantly higher air voids and AASHTO T166 provided significantly lower air void contents. Read the entire page →
From page 31... ... 4.9 4.3 4.0 3.8 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Dimensional Gamma Ray Vacuum-Sealing AASHTO T166 Test Method A ir Vo id C on te nt , % Letters represent results of Duncan's Multiple Range Test for air voids resulting from the bulk specific gravity methods. Methods with the same letter ranking are not significantly different.A B C C Figure 40. Read the entire page →
From page 32... ... The trendline suggested that as the ratio of lift thickness to NMAS increased, in-place air voids decreased. To determine if the relationship between in-place air voids and the t/NMAS ratio was significant, an ANOVA was conducted on the regression. Read the entire page →
From page 33... ... Relationship between t/NMAS and in-place air voids -- 9.5 mm, all data. thickness increased. Read the entire page →
From page 34... ... Relationship between t/NMAS and in-place air voids -- 19.0 mm NMAS. Read the entire page →

From page 5...

... However, for the 19-mm NMAS limestone SMA mix, 4 percent air voids could be achieved with 5.7 percent asphalt content, which did not meet the minimum asphalt content requirement in accordance with the "Standard Practice for Designing SMA," AASHTO PP44-01. Therefore, the minimum asphalt content of 6.0 percent was chosen, which resulted in 3.7 percent air voids at the design number of gyrations.