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Viscoelastic characterization and comparison of Norwegian asphalt mixtures using dynamic modulus and IDT tests
Published in Inge Hoff, Helge Mork, Rabbira Saba, Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 1, 2021
M. Alamnie, E. Taddesse, I. Hoff
Asphalt concrete (mixture) is a composite material constituted of aggregate particles embedded in a bitumen/binder. The asphalt binder firmly adheres to the aggregate particles and binds them to form asphalt concrete (a.k.a. bituminous mixture). Asphalt concrete is a viscoelastic material at small strain or stress levels, whereas it behaves in a nonlinear visco-elastoplastic manner at high temperatures and large deformations. Since the pioneering of the mechanistic-based design method, enormous research efforts are put forth towards developing more accurate and complicated testing methods. Various field and laboratory test methods are developed to characterize asphalt concrete in linear, nonlinear, viscoelastic, or viscoplastic states. A wide range of material data is needed to calibrate advanced pavement design models, which required extensive testing using advanced test equipment. However, equipment cost, complexity equipment/test method, and requirements skilled labor/time are imminent challenges.
Asphalt Binders
Published in M. Rashad Islam, Civil Engineering Materials, 2020
As cement is used in concrete, asphalt is used in asphalt concrete to bind aggregates together. The performance of asphalt concrete is primarily dependent on the amount and type of asphalt binder used. This chapter discusses the source, properties, grading, and laboratory characterization procedures of asphalt binder. Some non-conventional forms of asphalt binders, such as cutbacks, emulsion, and foamed asphalt, are also discussed.
Cumulative distress curve estimation from micromechanical asphalt model
Published in Eyad Masad, Amit Bhasin, Tom Scarpas, Ilaria Menapace, Anupam Kumar, Advances in Materials and Pavement Performance Prediction, 2018
I.O. Onifade, Y. Dinegdae, B. Birgisson
Asphalt concrete is a heterogeneous material usually made of aggregates, bituminous binder and air voids. The variation in the stiffness properties of the aggregates and binder, time-temperature-age dependent behavior of the binder, the shape of the aggregates and aggregate mineral composition, as well as spatial distribution of the constituents inside the mixture introduces a significant amount of complexity in the characterization and modeling of the material. Understanding the influence of the different mixture properties on the characteristic material behavior is not a trivial problem as it is understood that a change in one mixture property effects a corresponding change in the overall mixture morphological and mechanical properties.
Evaluating interaction of fibre reinforcement mechanism with mesostructure of asphalt concrete
Published in International Journal of Pavement Engineering, 2022
Hossein Noorvand, Samuel Castro, Benjamin S. Underwood, Kamil E. Kaloush
Roadway pavements are an essential constituent of the transportation infrastructure. Pavements built with asphalt concrete make up roughly 90% of the paved roads in the U.S.A. and over 99% of paved roads globally (USDOT 2010). Asphalt concrete is the popular paving material thanks to its lower initial cost compared with other alternatives, availability, ease of constructability, and ability to be used at both low-volume and high-volume traffic conditions. Still, these roadways are under ever growing demands to carry heavier traffic loads. With weathering and continued usage, asphalt pavements endure deterioration and need several maintenance activities during their designed service life. Therefore, scientists and engineers are constantly trying to improve the performance of asphalt mixtures and pavements including new road design, construction, maintenance, and management technologies, innovative materials, and techniques (Underwood 2011). Production of better-performing asphalts may not always be feasible through refining and processing improvements. Hence, modification of the asphalt concrete by incorporating new additives either in the bitumen or in the asphalt mixture is one of the common strategies to enhance the service lifetime of asphalt pavements. To this end, there are different types of modifiers, including various resins, rubbers, polymers, sulphur, metal complexes, fibres, and chemical agents (Park 2012).
Non-isothermal low-temperature reversible aging of commercial wax-based warm mix asphalts
Published in International Journal of Pavement Engineering, 2022
Yanjun Qiu, Haibo Ding, Ting Su
Asphalt binder is one of the most widely used materials in transportation infrastructures such as pavement. Recent years, this material also got more attention in railway and hydraulic engineering (Gaxiola and Ossa, 2019, Li et al., 2016). Therefore, the industry has imposed minimum requirements for the quality and durability of asphalt. The main advantages of asphalt concrete include the higher damping characteristic that could absorb more energy under vibration load, and ability of waterproofing if appropriately designed that may prevent moisture damage in structure. However, once cracking occurred in asphaltic structure, moisture would penetrate into the structure which may accelerate the stripping process and destroy the integrity of the structure. In asphalt concrete, cracks usually initiate at the binder itself or the interface between aggregate and binder. The latter cracking mode depends not only on the properties of asphalt but also on the surface properties of aggregate. For this reason, current pavement design specification usually specifies the properties of asphalt binder for controlling cracking frequency and easier implementation.
Investigation on internal structural properties of asphalt mixtures subjected to loading using image analysis
Published in International Journal of Pavement Engineering, 2022
Nawapol Brahmajaree, Kunnawee Kanitpong, Auckpath Sawangsuriya
Asphalt concrete is a composite material consisting of asphalt binder, aggregates and air voids which form a complex microstructure. Interaction between binder and aggregate contacts and spatial distribution of air voids plays important role in the macrobehaviour of asphalt concrete. In particular, aggregates constitute a supportive skeleton which provides a load-carrying capacity of the asphalt concrete. Zhu and Nodes (2000) showed that changes in mechanical or geometric properties of aggregate or binder affect overall stress–strain behaviour in an asphalt mixture. Vavrik et al. (2002) presented aggregate ratios, which are based on particle packing principles (Bailey method), for characterising the packing of an aggregate mixture and the resulting voids. A reliable method to characterise asphalt concrete microstructure is therefore required to understand the complex mechanical interactions existing between asphalt concrete components. Masad and Button (2004) reported that two-dimensional (2-D) or three-dimensional (3-D) imaging analysis techniques have often been used to characterise the internal structure of asphalt mixtures. Sefidmazgi et al. (2012) suggested that the 2-D imaging approach is more efficient compared to the 3-D technique as it can capture and quantify asphalt mixture microstructure in terms of simplistic parameters including number of contacts, contact length and contact orientation.