Download Free Evaluation Of The Use Of Polymer Modified Asphalt To Reduce Permanent Deformation In Asphalt Concrete Mixes In Hawaii Book in PDF and EPUB Free Download. You can read online Evaluation Of The Use Of Polymer Modified Asphalt To Reduce Permanent Deformation In Asphalt Concrete Mixes In Hawaii and write the review.

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.
Low density polyethylene (LDPE) when dispersed in asphalt cement through a high shear blending process produces asphalt concrete mixtures (Novophalt) with superior resistance to deformation at high service temperatures. The dispersion of LDPE within the asphalt results in rheological changes in the binder which not only significantly improve resistance to creep deformation but also improve mixture shear strength. The ratio of induced octahedral shear stress in a paving mixture to the octahedral shear strength of the paving mixture at the specific conditions of loading is used to demonstrate the ability of Novophalt to reduce deformation potential of asphalt pavements through improved shear strength. The results of the shear strength analysis are corroborated by creep deformation and accumulated permanent strain analyses.
This study evaluated and compared the effectiveness of polymer-modified asphalt mixes in improving the performance of the roadway in relation to rutting and cracking as compared to our standard mixes without modified binders. The addition of various polymers used in this study did not enhance the rut resistance potential of the mix, however the addition of the polymer did reduce the amount of transverse and longitudinal cracking to some extent.
Rubber-modified asphalt pavements have been used in Sweden and the United States since the 1970's. In these applications ground recycled tire particles (1/4 inch minus) are added to a gap-graded aggregate and then mixed with hot asphalt cement. The benefits of adding rubber to the mix include increased skid resistance under icy conditions, improved flexibility and crack resistance, elimination of solid waste, and reduced traffic noise. The major disadvantage of these rubber-modified mixes is their high cost in relation to conventional asphaltic concrete pavements. This research project consisted of a laboratory study of mix properties as a function of variables such as rubber gradation and content, void content, aggregate gradation, mix process, temperature, and asphalt content. Twenty different mix combinations were evaluated for diametral modulus and fatigue at two different temperatures ( -6°C, +10°C). Also, five different mix combinations were evaluated for static creep and permanent deformation. Layered theory was used to evaluate the effects of mixture variations on pavement life. The resulting information was used to develop guidelines for use of rubber asphalt mixes in United States road systems. The findings of the field survey indicate that the rubber-modified asphalt mixture is more susceptible than the conventional mixtures to preparation and compaction problems when adverse weather or equipment problems occur. However, with adequate equipment and favorable weather conditions, the rubber-modified asphalt mixture placement is similar to conventional mixture placement. The field study also indicates that stopping distances can be reduced 20 percent for the rubber-modified pavements in icy conditions. In view of the significant reductions in wintertime stopping distances under icy or frosty road surface conditions, the use of coarse rubber in asphalt pavements should be seriously considered. This is particularly true for areas such as bridge decks, on and off freeway ramps or insulated roadway sections. The findings of the laboratory study indicate that the rubber gradation and content, aggregate gradation, and use of surcharge during sample preparation have considerable effect on modulus and fatigue life of the mix. The results of static creep and permanent deformation tests indicate that the rubber asphalt mixes had low stability and high elasticity. Also, due to greater allowable tensile strain in rubber-modified mixtures, the thickness of the modified mixture can be reduced, using a layer equivalency of 1.4 to 1.0.
Polymer modified asphalts have recently been the focus of much attention in the U.S. due to claims that polymer additives will lengthen the life of an asphalt pavement. Much of the published research on this topic has been concentrated on the effects of polymer modifiers on binder and mixture properties. The goal of this testing is to predict from laboratory testing the actual field performance of an asphalt concrete. Over the years, specifications have been developed for conventional asphalts that allow pavement performance to be predicted from certain binder tests. These conventional binder tests do not fully address the special characteristics of polymer modified asphalt binders and need revision to be an effective tool in predicting pavement service life. This paper presents the findings of a two-part laboratory research program intended to relate binder and mixture properties of polymer modified asphalts. The preliminary testing involved five asphalt binder types and a variety of binder and mixture tests. Promising test procedures were further investigated in the final testing program where ten asphalt binders were examined. Simple linear regression was used to determine the strength of a relationship between pairs of binder properties and mixture properties. The preliminary testing showed penetration, toughness and tenacity, and force ductility to have the most promise in predicting mixture performance. The final testing contained enough data to be analyzed with both simple linear regression and multiple regression. Penetration, toughness and tenacity, force ductility again were the test procedures that had binder properties that correlated well with mixture properties.