Effect of copper slag addition on mechanical behavior of asphalt mixes containing reclaimed asphalt pavement

• Marshall and ITS tests reveal the optimal percentage of copper slag to be used.
• The use of copper slag reduces asphalt mix rigidity with RAP.
• Asphalt mix with copper slag perform better at low rather than high temperatures.
• A stiffening effect of fine material appears when copper slag exceeds 15% addition.

Annually, copper production and refining processes of generate large volumes of copper slag, and the disposal of this waste remains a major economic and environmental problem. This annual production causes an increase in the number and volume of landfills, as well as the quantity of slag that backs up landfills, it also produces leachates which contain metals such as Cu, Pb, Hg and SO2. In this research, friction and cohesive qualities of copper slag are exploited, in order to incorporate this slag as aggregate in asphalt mixes containing Reclaimed Asphalt Pavement (RAP). Results demonstrate that the use of copper slag in an addition percentage of 35% is favorable, because flow values increase and stability values decrease. The Marshall Quotient is reduced up to 27%, improving the performance of mixes with RAP and obtaining behavior similar to a traditional mixture. This improvement is also reflected in an 8% increase in the indirect tensile strength, which stands the use of copper slag as a solution in RAP applications with more demanding tensile and fatigue requirements.

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