This paper presents the results of investigations on the rheological properties of modified asphalt binders and their influence on the performance of asphalt mixes. Asphalt mixes with modified binders such as styrene butadiene styrene polymer, crumb rubber, natural rubber, and waste plastics were evaluated for their rheological properties and compared to the properties of asphalt mixes with unmodified VG30 (viscosity grade) asphalt binder. The dynamic modulus values and rutting characteristics of the asphalt mixes were studied with due consideration to different levels of aging and temperature variations. Studies on the rheological properties showed that the energy dissipated by unmodified asphalt (VG30) binder is higher than that of modified asphalt binders. Long-term aged natural rubber and waste plastic modified asphalt binders showed significant increase in the properties compared to unmodified asphalt binder (VG30). Reduced temperature susceptibility of polymer modified asphalt binder showed that only polymer modification can enhance both high temperature rutting resistance and low temperature thermal cracking resistance of asphalt mixes. The transient nature of polymer modified asphalt mix from viscoelastic solid-like to viscoelastic fluid-like condition is significantly shifted to higher temperature compared to that of the mix with unmodified asphalt binder. Aging and rutting indices showed that rubber modified asphalt mixes are highly susceptible to aging. Statistical analysis of test results showed that the process of modification of asphalt binder, aging, and temperature during the test influence the rheological and rutting characteristics of asphalt mixes significantly. Correlation between the asphalt binder properties and its influence on the rutting resistance are found to be statistically significant. The analysis using least significant difference showed that polymer modified asphalt binder significantly improves the aging and rutting resistance of asphalt mixes compared to unmodified asphalt binder.

This book gathers the proceedings of the 1st Global Civil Engineering Conference, GCEC 2017, held in Kuala Lumpur, Malaysia, on July 25–28, 2017. It highlights how state-of-the-art techniques and tools in various disciplines of Civil Engineering are being applied to solve real-world problems. The book presents interdisciplinary research, experimental and/or theoretical studies yielding new insights that will advance civil engineering methods. The scope of the book spans the following areas: Structural, Water Resources, Geotechnical, Construction, Transportation Engineering and Geospatial Engineering applications.

Now updated, this volume serves as a single resource to supplement Superpave PG asphalt binder system test methods. This new edition contains a chapter on the direct tension test (DTT), an introduction to the new multi-stress creep-recovery test (MSCR), a troubleshooting section and updated graphics.

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.