چكيده به لاتين
Increasing societal awareness of the environmental effects of constructing, operating, and maintaining the highway infrastructure has led to new demands on transportation agencies to conduct their business in a more environmentally friendly, or sustainable fashion. Microsurfacing is an environmentally friendly cost-effective preventative maintenance treatment that is used to protect pavements. In the new decade of environmental awareness, maximizing recycled materials are a priority. For each ton of magnesium produced by silicothermic reduction method, there will be about 6-7 tons of the slag will left. The amount of magnesium slag is increasing, and the damage it poses to the environment attracts more attention. In the following study, the performance of the protective asphalt of microsurfacing containing magnesium slag filler (aggregates passing sieve No. 200) was evaluated. To this end, in the first section, the chemical and physical properties of stone materials and emulsion bitumen were investigated. Afterwards, SEM-EDS, XRD, XRF, and FTIR tests were performed to identify the microstructure of magnesium slag and its chemical interactions with emulsion bitumen. In the second section, the microsurfacing mixtures were prepared with five different compositions containing magnesium slag filler at 0%, 25%, 50%, 75%, and 100% levels as the replacement for the aggregates passing through the 0.075-mm sieve. The performance of the samples was evaluated by experiments including wet cohesion test, wet track abrasion test, and loaded wheel test, according to ISSA A143 guideline and ASTM D6372 standard. Subsequently, variance analysis (ANOVA) was used to explore the effect of magnesium slag on the performance of the microsurfacing. Finally, TCLP test was administered to investigate the amount of heavy metals in magnesium slag and the microsurfacing containing magnesium slag. The results of the design have indicated that the mixture containing the magnesium slag at 50, 75 and 100% level could improve the microsurfacing performance compared to the best control sample in terms of adhesion, abrasion resistance, bleeding, vertical, and lateral displacement by 22%, 68%, 13.0%, 36%, and 17%, respectively. In addition, the findings generated from TCLP test have shown that magnesium slag and the microsurfacing containing magnesium slag has no environmental issues with leaching. As general conclusion, the amount of slag used in the microsurfacing composition can be determined by economic, environmental, and technical goals for sustainable development.
