The use of copper slags as an aggregate replacement in asphalt mixes with RAP: Physical–chemical and mechanical behavioural analysis. (30th November 2018)

• Record Type: Journal Article
• Authors: Raposeiras, A.C.; Movilla-Quesada, D.; Bilbao-Novoa, R.; Cifuentes, C.; Ferrer-Norambuena, G.; Castro-Fresno, D.
• Is Part Of: Construction & building materials. Volume 190(2018)
• Page Start: 427
• Page End: 438
• Publication Date: 2018-11-30
• Subjects: Copper slag -- Reclaimed asphalt pavement -- Physical-chemical characterization -- Marshall stiffness -- Indirect tensile strength -- Resilient modulus; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.09.120
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: CS has a unique physical interaction with the binder, with no chemical interaction. When adding CS, the excessive rigidity is reduced in mixes with RAP. Deformation is due to the lack of affinity of aggregate and CS with the aged binder. Combinations of RAP and CS between 45% and 55% improve the behaviour of the mixes. The size of the reused materials does not influence the behaviour of the mixes. Abstract: Copper slag (CS) is a derivative of copper production that is mainly composed of heavy metals. The large amount of this material accumulated around the world entails a serious environmental danger. Its use as a replacement of mineral aggregate in asphalt mixtures would allow to increase the durability and resistance, taking advantage of its physical-chemical properties. In this research, physicochemical analyses of different combinations of CS, reclaimed asphalt pavements (RAP), asphalt cement and aggregates by X-Ray Diffraction (XRD) and Fourier-Transform InfraRed spectroscopy (FT-IR) were developed. Subsequently, Marshall stiffness ratio, indirect tensile strength (IDT) and resilient modulus tests were performed to determine their implication in mechanical behaviour. Asphalt mixes with ranges from 45 to 55% of recycled material have improved stability, Marshall Flow and Stiffness ratio, obtaining values comparable with those from a conventional mixture. At the same time, its resilient modulus and IDT values increased by 35% compared to conventional mixes. To maintain values similar to conventional mixes, when the amount of RAP decreases the amount of CS should be increased, with a maximum value of 35%. This behaviour is explained by the presence of fayalite and magnetite in CS, which are hard, dense and hydrophobic components that produce increased elastic deformation of the binder before breaking.