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Ethylene-Octene-Copolymer as an alternative to Styrene-Butadiene-Styrene bitumen modifier
Published in Inge Hoff, Helge Mork, Rabbira Saba, Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 1, 2021
A. Riekstins, V. Haritonovs, R. Merijs-Meri, J. Zicāns
One way to reduce the costs is to use thinner asphalt layer(s) so that less bitumen and also a modifier are needed. In Latvia, the thickness of the top layer is usually designed to be 35-40 mm. The main aim of the wearing course is to provide a smooth surface and load transfer. The thickness of the top layer could be optimized if better quality aggregates and modified bitumen are used (Kragh et al., 2011) in case the reduction of the wearing course is not compensated by another thicker structural layer. Very thin asphalt concrete (BBTM) is a promising alternative to conventional asphalt mixtures (A. Riekstins, Haritonovs, Abolins, Straupe, & Tihonovs, 2019; Arturs Riekstins, Haritonovs, & Straupe, 2020). BBTM could be used on high-intensity roads because of the durable mineral carcass. Typically, the thickness of the wearing course is 20 to 30 mm. By using BBTM instead of conventional asphalt mixtures such as asphalt concrete (AC) or stone mastic asphalt (SMA), it is possible to reduce the consumption of aggregates and binder up to 50%. Such reduction is particularly important for countries and regions that import aggregates and/or bitumen. However, the use of BBTM mostly increases the use of PMB. Thus, it is not possible to avoid the use of polymers, but it is possible to find an alternative to SBS.
Structural design of haul roads
Published in Thompson Roger J., Peroni Rodrigo, Visser Alex T., Mining Haul Roads, 2019
Thompson Roger J., Peroni Rodrigo, Visser Alex T.
The designs discussed in this chapter make use of a selected (blasted) waste rock layer as the base component of the road. When a selected (blasted) waste rock layer is located immediately under the wearing course, road performance is significantly improved, primarily due to the load carrying capacity of the waste rock layer, which reduces the susceptibility of the softer sub-grade or in-situ to the effects of high axle loads. The rock layer is the primary structural layer and should be placed as near the surface as possible. It serves no purpose to bury it and then cover it with typical gravel and crushed stone layers as is used for public roads. The wearing course is a protective layer that ensures a vehicle-friendly ride and good functional performance. Wear of the wearing course could result in rocks from the dump rock layer being in contact with the tyres, which could result in early tyre failure. There is thus a minimum thickness of wearing course that can be constructed. A minimum practical thickness is 100 mm, which is used on short-term roads. On the more permanent roads a wearing course thickness of 200 mm is placed to avoid having to regravel the road every year, as such a thickness should last at least three years with careful light grading.
Life cycle cost analysis of runway reconstruction alternatives for commercial service airports
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
The final wearing course of the asphaltic concrete overlay would expect to last for 5 years before a milling and replacement surfacing of the asphalt layer would be required, again at night. This case is essentially a four-step process on successive nights to completion. The construction process is as follows: Selected slab replacements at night using fast setting portland cement concrete.Rubberized asphalt as an isolation layer and leveling course.Geogrid fabric and traditional dense asphalt layer to serve as a structural layer.Final structural dense asphalt layer to serve as the wearing course
Chemical composition, morphology, and distribution of particulate matter produced by road pavement abrasion using different types of aggregates and asphalt binder
Published in Cogent Engineering, 2021
Dusan Jandacka, Dasa Kovalova, Daniela Durcanska, Martin Decky
Vehicle motions cause mechanical wearing of pavement surfaces by vehicle tires, which leads to gradual fragmentation, abrasion, and polishing of aggregates (Florkova & Jambor, 2017). The abrasion reduces aggregate angularity on the asphalt mixture surface and thus creates the condition for gradual polishing of used aggregate (Florkova & Pepucha, 2017). Asphalt pavements are the most extensively used type of road pavement. The most commonly used asphalt mixtures for wearing courses are asphalt concrete (AC) and stone mastic asphalt (SMA). The individual asphalt mixtures differ from each other by the relative proportion of the individual components, which affects the final mixture properties, appearance, and surface texture.