Optimization of electric arc furnace aggregates replacement in dense-graded asphalt wearing courses
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International Journal of Pavement Research and Technology Journal homepage: www.springer.com/42947
Optimization of electric arc furnace aggregates replacement in dense-graded asphalt wearing courses Federico Autelitano*, Felice Giuliani Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze, 181/A - 43124 Parma, Italy Received 10 April 2020; received in revised form 7 August 2020; accepted 17 August 2020
Abstract
Electric arc furnace (EAF) aggregates, by-products of the homonymous steelmaking process, represent an ideal solution for asphalt mixtures, above all for wearing courses where skid resistance and durability are essential functional requirements. Their use, which is subordinate to the compliance of chemical specifications, finds some practical interest limits mainly related to transportation (extremely high bulk specific gravity) and placement (unsatisfactory compaction) operations. Thus, the aim of this experimental study was to determine an ideal artificial to natural aggregates replacement rate, also identifying the most suitable particle size range, for dense-graded asphalt wearing courses. The results highlighted how the best balance between compaction and mechanical performances was registered by a mix which was formulated considering a partial replacement of 54% (v/v%), distrib uted only in the coarsest fraction. The introduction of limestone as “excipient” in the coarse-fine and finer size ranges reduces the weight of the mixture, guaranteeing at the same time an optimum compaction degree, high levels of stiffness in the viscous-elastic region and Marshall stability and extended fatigue life. Keywords: Steel slag; Industrial by-product; Recycled material; Hot mix asphalt; Pavement engineering; Compaction
1. Introduction The future of construction, and in particular of road construction, unavoidably passes through the paradigm of the circular economy and the application of strategies aimed at reducing the impact of interventions and pushing the recycling of materials [1]. In this perspective, many countries have developed policies for limiting the materials extracted from quarries and enhancing the re-use of reclaimed asphalt pavement (RAP) or the recycling of industrial wastes and by-products that otherwise would be send to landfills for disposal [2-5]. Thus, several in-place or in-plant recycling techniques for old asphalt pavements, based on hot and cold procedures, have become established over the years [6-10]. Besides, many cross-sectoral projects have seen the development of symbiotic collaboration with industries for the implementation of innovative technological processes able to transform waste into valuable and cost-effective construction materials [11,12]. In this “end of waste” context, a preferential partner and stakeholder for the road construction sector has been the steel * Corresponding author E-mail address: [email protected]; https://orcid.org/00000003-0780-9438 (F. Autelitano); [email protected]; http://orcid.org/0000-0002-8
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