Electric ARC furnace steel slag and copper mine tailing as asphalt paving materials
Date
2015
Authors
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Journal ISSN
Volume Title
Publisher
Universiti Teknologi Malaysia
Abstract
Natural aggregates are becoming depleted due to high demand in road construction. Therefore, the use of alternative materials, which could preserve natural aggregates and promote environmental sustainability, should be encouraged. For this study, an investigation into the suitability of electric arc furnace (EAF) steel slag and copper mine tailing (CMT) as alternative asphalt paving materials was proposed. The research was carried out in three stages. Initially, the mechanical and physio-chemical characterisations were performed separately on these materials. In addition, the micro-structure analysis and the leachability tendency of the materials were assessed. In the second stage, basic tests were performed on two types of bitumen binders: penetration grade 80-100 and PG 76; and EVA modified 80-100. The tests included dynamic shear rheometer test, softening point test, viscosity test, and penetration test. The final stage involved laboratory tests to evaluate the performance of mixtures incorporating EAF steel slag and CMT. Four material mixtures of sixteen mix designs consisting of eight AC 14 designed mixes and eight SMA 14 designed mixes were evaluated. Mix 1 was 100 % granite, Mix 2 consisted of 80 % granite and 20 % CMT, Mix 3 consisted of 80 % EAF steel slag and 20% CMT while Mix 4 consisted of 40 % EAF steel slag, 40 % granite, and 20 % CMT. Results from the volumetric analysis indicated that the optimum binder content of the mixes incorporating EAF steel slag and CMT is slightly higher compared to the control mix. Also, Mix 3 possessed better Marshall stability and Marshall quotient compared to the other mixes. The microstructure analysis of the materials showed that both CMT and EAF steel slag were more porous and rougher than granite, which strengthened their bond with asphalt materials. The results of the TCLP test indicated that the concentrations of the five selected heavy metals were far below the regulatory limit for all the samples and the aggregates. The test results further indicated that mixes containing EAF steel slag and CMT were less susceptible to rutting and permanent deformation compared to the control mix. In addition, incorporating EAF steel slag and CMT into the asphalt mix significantly improved the skid resistance of the mixture. Hence, it is proven that EAF steel slag and CMT are promising alternative aggregates that can be used as asphalt paving materials.
Description
Thesis (PhD (Civil Engineering))
Keywords
Roads—Design and construction—Research, Road materials—Testing, Sustainable construction—Materials