Effect of Waste Oil Shale Ash on Properties of Asphalt Cement and Asphalt Concrete Mixtures: State of the Art

摘要

With the development of the road pavement industry and increasing traffic on streets, construction materials have likewise been developed and progressively non-conventional materials have been incorporated. The main idea behind the utilization of those non-conventional materials was the shortage of natural materials and their expensive cost which have supported the inclination towards the inclusion of waste and marginal materials that has also assisted in achieving environmental sustainability in asphalt pavement design and construction. Researches have shown that there is a variety of waste materials that can be used effectively in different layers of pavement system such as oil shale ash (OSA). OSA is considered undesirable and environmentally dangerous as a byproduct of direct combustion or retorting of oil shale. However, research has recently shown that this ash has many benefits that improve the asphalt mixture. Accordingly, this paper presents a systematic review of the performance evaluation of different types of OSA modified asphalt cement and asphaltic concrete mixes, in terms of the most successful ratio to be added and the extent to which the properties of asphalt mixtures were affected by this addition. It was concluded that there is a consensus among the researchers that adding OSA to concrete mixture improved its conventional and rheological properties and reduced its potential for stripping and creep damaging, where the optimum ratio of OSA to be added was recommended to be in the range of 5–15% by the volume of binder.