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The use of hydrated lime in Hot-Mix Asphalt (HMA) mixtures can reduce permanent deformation, long-term aging, and moisture susceptibility of mixtures. In addition, hydrated lime increases the stiffness and fatigue resistance of mixtures. This study evaluated (1) the fundamental engineering properties of HMA mixtures containing hydrated lime as compared to conventional mixtures designed to meet the current Louisiana Superpave specifications and (2) the influence of the method of addition of hydrated lime on the mechanical properties of HMA mixtures. A Louisiana Superpave 19.0 mm Level II HMA mixture design was utilized. Siliceous limestone aggregates and three asphalt binders, a neat PG 64-22 and two Styrene-Butadiene (SB) polymer modified binders meeting Louisiana specifications for PG 70-22M and PG 76-22M were included. Based on the same mixture design, three conventional and six hydrated lime treated HMA mixtures were developed. The conventional mixtures contained no hydrated lime and the three aforementioned asphalt binders respectively. The lime treated mixtures were produced by incorporating hydrated lime into the HMA mixture in two ways: "slurry" or "paste" method when hydrated lime was mixed with the aggregate as slurry and "dry" or "no-paste" method when dry hydrated lime was blended with the asphalt binders. For each lime treatment method, three HMA mixtures were produced using the three identical asphalt cements (PG 64-22, PG 70-22M, and PG 76-22M) utilized in the three conventional mixtures. The overall results from mechanistic tests on HMA mixtures and rheological tests on asphalt binders indicated that the addition of hydrated lime improved the permanent deformation characteristics of the HMA mixtures. This improvement was substantial particularly at higher testing temperatures for mixtures containing polymer modified asphalt binders.
In this study, conventional asphaltic concrete mixtures and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by indirect tensile strength and strain, permanent deformation characteristics, resilient modulus, and fatigue resistance. A dense graded mixture meeting the Louisiana Department of Transportation and Development Type 3 specification (low stability, low volume
Strategic Highway Research Program (SHRP) A407 recommends that aggregate gradations pass below the restricted zone as traffic level increases. This study investigated the use of natural sand in the fine and coarse gradations for the surface course mixtures. The mixtures were designed using the SUPERPAVE mix design approach and were evaluated for their performance in terms of resistance to rutting, fatigue and moisture damage. In addition, the accelerated performance of these mixtures was also evaluated using the Asphalt Pavement Analyzer.
Approximately 89% of 11,000 miles of Kansas roads are surfaced with asphalt. Hundreds of thousands of tons of reclaimed asphalt pavement (RAP) are produced annually in the United States, including in Kansas. This bulk volume of RAP must be economically managed in order to achieve environmental friendliness. Recycling of RAP conserves natural resources and reduces landfill usage. However, many agencies have reported that increased RAP content produces drier hot-mix asphalt (HMA) mixtures than virgin mixtures that are susceptible to premature cracking. In this research, laboratory-produced Superpave HMA mixtures containing increased percentages (20, 30, and 40%) of RAP materials from three RAP sources (Shilling Construction Co., Konza Co., and the Kansas Department of Transportation's project, US 73) were studied for cracking performance. Mix designs were produced using Superpave design criteria for 12.5-mm nominal maximum aggregate size mixture. The static and repetitive Semicircular Bending (SCB) test, the Texas Overlay Tester test, the dynamic modulus test, and Viscoelastic Continuum Damage (VECD) tests were performed on laboratory-prepared samples. In general, cracking performance decreased with increased RAP content. The RAP from the US 73 project performed most consistently compared to other two sources of RAPs. Test results were analyzed using two-way Analysis of Variance (ANOVA), proving that mixtures containing 4.5% to 4.9% binder performed the best against cracking. The RAP source was found to have more effect on cracking propensity than RAP content. Mixtures with RAP content up to 40% performed satisfactorily. Tukey's pairwise comparison method was used to compare results from all tests; VECD was determined to be the most appropriate test to evaluate cracking propensity of HMA mixtures.