WPB holds the view that road network preservation has become an increasingly complex challenge, particularly among countries managing extensive highway networks with poor finances. The constant need for maintenance under high traffic conditions has encouraged researchers and policymakers to seek more sustainable road construction materials. Within this background, application of Reclaimed Asphalt Pavement (RAP) and Crumb Rubber (CR) to asphalt mixtures has been an economic and eco-friendly approach with cost-saving and environmental advantages.
Unlike previous studies that focused primarily on laboratory testing, this research leverages field-tested evidence by analyzing cores of the pavement from the Islamabad–Lahore (M-2) motorway. The research not only attains laboratory-level reliability but also real-world understanding of how modified asphalt behaves under actual service conditions.
Research Focus and Methodology
The main aim of the research was to determine the effect of RAP and CR on three major performance parameters, which include rutting resistance, tensile strength, and resilient modulus. Four motorway sections were under test: a normal asphalt control, a 7% crumb rubber mixture, an additional 15% reclaimed asphalt mixture, and finally a mix of 15% RAP with 7% CR. Cut pieces of cores from each section underwent globally standardized test procedures like the Hamburg Wheel Tracking Test (HWTT), Indirect Tensile Strength (IDT) test, and Resilient Modulus (MR) test to ensure comparability with the global standards.
Rutting Resistance Results
Rutting, a common problem in high-temperature and repeated traffic-resistant flexible pavements, was assessed with the HWTT. The results showed that modified mixtures were better than the control asphalt, and the RAP + CR mixture was the most resistant to permanent deformation. Although the RAP-only and CR-only mixes also performed better, their resistance was not as good as the dual-modified section. This synergy describes the structural durability benefit of recycling components combined together.
Tensile Strength and Cracking Resistance
Fatigue and temperature cracking is a persistent issue in highway performance. The IDT test confirmed that recycled content mixtures were more tensile in strength. The RAP + CR mixture was the most increased, then CR-only mix, followed by RAP-only, with the control asphalt experiencing minimal resistance. Elasticity of the crumb rubber and hardness of the RAP together resulted in a balanced mix, well able to withstand cracking stresses.
Resilient Modulus Behavior
Pavement capability to recover from repeated traffic loading was measured through resilient modulus testing. Results confirmed that modified asphalts—particularly the RAP + CR blend—were more resilient and elastic than regular asphalt. Synergistic combination of CR flexibility and RAP stiffness produced a flexible, resilient mix. Regular asphalt, in contrast, had the lowest modulus, which pointed to its relative susceptibility to heavy use.
Practical and Environmental Value
The consistent gains achieved in all the test performances confirm the feasibility and benefits of using recycled materials in road construction. In a practical way, the approach reduces the instances of costly repairs and extends the pavements' service life. Environmentally, RAP application reduces the use of virgin aggregates and binders, while CR addresses the issue of timely disposal of waste tires. For poorer nations with high rates of rehabilitation needs, such as Pakistan, these solutions represent a move towards economic rationality as much as environmental sustainability.
Broader Implications
This study contributes to the global pursuit of sustainable infrastructure as it validates, from the field, the effectiveness of RAP and CR as modifiers. Previous uncertainty regarding their performance in actual conditions is addressed through the analysis of motorway cores under actual traffic and climatic conditions. The study also provides comparative analysis, indicating how the single-modifier and dual-modifier blends compare, hence offering practical guidelines for material selection according to project goals and budget constraints.
Conclusion
The test results clearly show that RAP-and-CR-modified asphalt is superior to conventional mixtures in rutting resistance, tensile strength, and resilient modulus. Of all the sections tested, double-modified blend was superior to all of them, again proving the complementarity of the benefit of modifying with these materials in combination. Besides technical improvement, this technique encourages sustainable development by reducing waste and conserving natural resources. Through the documentation of field-level results, the study offers engineers and policymakers effective evidence to defend the utilization of recycled materials in modern pavement construction.
By WPB
Asphalt, Bitumen, Road
If the Canadian federal government enforces stringent regulations on emissions starting in 2030, the Canadian petroleum and gas industry could lose $ ...
Following the expiration of the general U.S. license for operations in Venezuela's petroleum industry, up to 50 license applications have been submit ...
Saudi Arabia is planning a multi-billion dollar sale of shares in the state-owned giant Aramco.
