Evaluation of Marshall stiffness, indirect tensile stress and resilient modulus in asphalt mixes with reclaimed asphalt pavement and copper slag

Abstract

Asphalt mixes with Reclaimed Asphalt Pavement (RAP) offer many advantages when reusing this material. But without the adequate treatment, these mixtures present durability problems due to the material’s loss of properties over time. The use of copper slag can reduce these problems through its physical-chemical properties, such as highly angular characteristics, lime content in its composition and low silica content, while contributing with friction and strong adhesive characteristics. On the other hand, the amount of copper slag stockpiles and their associated lixiviation are also reduced. This work presents the results obtained in asphalt mixes with RAP percentages from 0 to 40%, combined with copper slag percentages ranging from 0 to 35%. Sixteen (16) combinations of materials were used to prepare Marshall specimens in order to carry out stability and flow tests, indirect tensile strength tests and resilient modulus by diametral compression. The use of copper slag improves the performance of asphalt mixes with RAP. With 15% copper slag amounts by mass, the stability and flow values are stabilized, thereby improving the Marshall stiffness index. The values for indirect tensile strength and resilient modulus with RAP percentages over 20% are also improved, especially in mixtures with high RAP percentage (40%). These results favor the use of RAP in applications that require more demanding parameters.