The objective of this paper is to assess the effects of adding two modifiers of different chemical nature on the rheological behavior of asphalt-rubber binders: the shale-oil residue and the polyphosphoric acid. Four modified asphalt-rubbers were prepared: asphalt-rubber-PPA (18 % crumb rubber + 1 % PPA), asphalt-rubber-oil (18 % rubber + 10 % shale-oil residue), asphalt-rubber-oil-PPA-1 (18 % rubber + 10 % oil + 1 % PPA) and asphalt-rubber-oil-PPA-2 (9 % rubber + 5 % oil + 0.5 % PPA). A reference asphalt-rubber was prepared using 18 % crumb rubber. The samples were submitted to oscillatory-shear tests to obtain data (complex modulus, G*, and phase angle, ?) to construct master curves. Compared to the base asphalt binder, the pure asphalt-rubber improves the rutting and strain-controlled fatigue resistances. The addition of 1 % PPA enhances even more the rutting resistance and improves slightly the fatigue resistance below 20°C. The most substantial increase in fatigue resistance is obtained when 10 % oil is added to the pure asphalt-rubber, but its rutting resistance is drastically reduced. Mixtures 1 (18 % rubber + 10 % oil + 1 % PPA) and 2 (18 % rubber + 5 % oil + 0.5 % PPA) have lower rutting resistance compared to the base asphalt-rubber, but only mixture 1 has higher fatigue resistance. Compared to the base asphalt binder, all modified asphalt-rubber binders present higher G*/sin? values (at all rutting temperatures) and lower G*.sin? values (only below 20°C) when traffic speed reduces. Taking this evidence into account, the asphalt-rubber and the asphalt-rubber-PPA are the most appropriate. Although shale-oil residue has shown opposite results at intermediate and high pavement temperatures (enhancing the fatigue resistance and reducing the rutting resistance), it is able to reduce the viscosity of the asphalt-rubber, enhancing the workability of the HMA mixes during construction.

The objective of this study was to perform a preliminary evaluation of improving bonding and aging characteristics using a distillation residue from the Green River Formation (western) shale oil as a modifier to a petroleum asphalt for use as a crack and joint filler material in portland cement concrete and asphaltic pavements. This study was to examine the differences in moisture damage resistance and adhesion properties, as measured by bonding energy, of shale-oil modified asphalts compared with non-modified asphalts. The shale-oil modified asphalts mechanical properties were not expected to match those of the rubberized asphalt. A commercially available rubberized asphalt crack and joint filler material was also tested only for comparison of mechanical properties. Portland cement concrete briquets prepared with an asphalt material sandwiched between two concrete wafers were tested in a stress-relaxation type of experiment to evaluate the relaxation and recovery properties of the sealant materials. Energy of interaction (bonding energy) measurements were performed on asphalt materials with portland cement concrete, two silicate aggregates, and a limestone aggregate to evaluate the compatibility of the asphalt materials with various aggregates. The results show that the shale-oil modified petroleum asphalt improved the relaxation time, percent recovery, and bonding energy compared with the petroleum asphalt.

"ASTM Publication Code Number (PCN) 04-011080-08. - "Sponsored by ASTM Committee D-4 on Road and Paving Materials."-- Foreword. - Includes bibliographical references and indexes. - Electronic reproduction; W. Conshohocken, Pa; ASTM International; 2011; Mode of access: World Wide Web; System requirements: Web browser; Access may be restricted to users at subscribing institutions.

The performance of projects incorporating asphalt-rubber binders has been inconsistent. Thus, a method was needed to provide an understanding of binder physical properties associated with the desirable performance and to quantify them for specification purposes. It was proposed to use the capabilities of a dynamic shear rheometer for comparing the asphalt-rubber binder properties with project performance data to determine the potential for rheological specifications on job samples of the binder. Representative binders from six dense-graded and gap-graded hot mix projects were analyzed.

A dozen papers from a December 1993 symposium in Dallas/Fort Worth, Texas. Among the topics are why the new proposed rheological properties of asphalt binders are required and how they compare to conventional properties, the development and use of the SHRP direct tension specification test, oxidatio