摘要: |
This report documents the performance of Louisiana Superpave mixtures through laboratory mechanistic tests, mixture volumetric properties, gradation analysis, and early field performance. Thirty Superpave mixtures were evaluated in this study. Fourteen of them were designed for high volume traffic (> 30 million ESALs), twelve for intermediate-volume traffic (between 3 and 30 million ESALs), and four for low volume traffic (< 3 million ESALs). Four aggregate types: limestone, sandstone, novaculite, and granite and five binder types: AC-30, PAC-30, PAC-40, PG 70-22M, and PG 76- 22M were included in the mixtures. Four MTS tests: the indirect tensile (IT) strength, IT resilient modulus, IT creep, and axial creep, three Superpave Shear Tester (SST) tests: frequency sweep at constant height (FSCH), repeated shear at constant height (RSCH), and simple shear at constant height (SSCH), and the Asphalt Pavement Analyzer (APA) rut test were included in the testing program of this study. The test results showed that high volume mixtures appeared to have higher IT strengths, lower IT and axial creep slopes, and higher shear stiffnesses when compared to those of low volume mixtures. This indicates that high volume mixtures generally possessed better rut resistance than the low volume mixtures considered. The compaction efforts (the N-design levels), dust/AC ratio, film thickness, and the percent of aggregate passing the 0.075 mm sieve were observed to have certain relations with the rut susceptibility of Superpave mixtures. The Power-law gradation analysis indicated that all four Power-law gradation parameters (aCA, nCA, aFA, and nFA) were sensitive to the mixture mechanistic properties evaluated. This implies that the proposed Power-law gradation analysis could be used as the bridge between aggregate gradation design and mixture performance evaluation. Finally, the early field performance of those Superpave mixtures was studied and compared to their laboratory performance test results. |