Optimization-Based Study on the Use of Granulated Copper Slag in Bituminous Base Layers
1Dr. M. MADHURI, 2KAMPARA VIJAYA
1 Associate Professor& HOD, 2 PG Student
1,2 Department Civil Engineering
Sanketika Vidya Parishad Engineering College, Visakhapatnam, Andhra Pradesh
Abstract -Industrial waste generation has increased significantly in recent decades, creating major environmental and land management challenges. Among these wastes, Granulated Copper Slag (GCS) from non-ferrous metallurgical industries is produced in extremely large volumes, with the copper industry generating 99% waste for every 1% metal recovered. This study focuses on evaluating the suitability of GCS as an alternative fine aggregate in bituminous pavement layers, aiming to promote sustainable material utilization and reduce dependence on natural aggregates. The research involves detailed chemical characterization, physical property evaluation, environmental safety assessment, and mix design optimization of GCS for use in Copper Slag Dust Base (CSDB) layers. Chemical analysis shows that GCS contains 43% iron, 34.9% silica, and only trace amounts (<1%) of potentially hazardous elements such as cadmium, arsenic, cobalt, and lead. Toxicity Characteristic Leaching Procedure (TCLP) results confirm that all leached metals fall well within EPA regulatory limits, indicating that GCS is safe for pavement use. Physical property comparison further shows that GCS satisfies ASTM D1073 and AASHTO M29 requirements for fine aggregates. To determine optimum usage, seven GCS–quarry dust combinations were evaluated using Grading Index (GIc) values ranging from 0.20 to 0.80, corresponding to GCS contents varying from 20% to 80%. Mix design trials were conducted using 80/100 grade bitumen at binder contents of 4.5%, 5.0%, 5.5%, and 6.0%, compacted with 75 blows per side as per Marshall standards. The resulting CSDB mixes exhibited acceptable stability, air voids, VMA, VFB, and flow characteristics across multiple GIc combinations. Optimization revealed that mixes with 40–67% GCS (GIc = 0.40 to 0.67) provide the best balance of strength, workability, and specification compliance, enabling high-volume utilization without compromising performance. Overall, the study demonstrates that GCS can be effectively incorporated as a sustainable aggregate alternative in bituminous base layers. Its chemical safety, favorable physical characteristics, and successful performance in CSDB mix designs confirm its potential for large-scale application in flexible pavement construction.
Key Words: GCS, Bituminous layers, Copper slag dust base, Mix design, Marshall stability
