Performance Evaluation of HDPE-Bakelite Dual-Modified Asphalt Mixtures for Sustainable Pavements

Area of Science:

• Materials Science
• Civil Engineering
• Environmental Science

Background:

• Flexible pavements face distress like rutting and moisture damage in hot climates.
• Extreme temperatures (>45 °C) in regions like Pakistan exacerbate pavement degradation.
• Conventional bitumen binders require enhancement for improved durability.

Purpose of the Study:

• To investigate the synergistic effects of dual modifiers: High-Density Polyethylene (HDPE) and Bakelite.
• To enhance asphalt mixtures for improved performance in extreme hot climates.
• To assess the sustainability and cost-effectiveness of using waste-derived materials.

Main Methods:

• Asphalt mixtures were modified using a wet process with varying percentages of HDPE (3%, 6%, 9%) and a fixed 6% Bakelite.
• Performance was evaluated using indirect tensile strength (ITS), tensile strength ratio (TSR), resilient modulus, and Hamburg wheel tracking tests.
• Modified mixtures were compared against control mixtures using conventional bitumen and NHA Class-B gradation.

Main Results:

• The optimal 6% HDPE + 6% Bakelite formulation showed significant improvements: 24.7% higher dry ITS, 48.7% higher conditioned ITS, 95.36% TSR, 43.7% greater resilient modulus, and 27.4% lower rutting depth.
• These enhancements are attributed to a stiffer polymer resin network formed by HDPE and Bakelite.
• Higher HDPE content (9%) showed potential phase separation impacting strength but continued to improve rutting resistance.

Conclusions:

• Dual modification with HDPE and Bakelite offers a sustainable and cost-effective method to enhance pavement durability in hot climates.
• This approach addresses waste management challenges by utilizing recycled materials.
• The improved performance characteristics suggest potential for reduced maintenance costs and extended service life of flexible pavements.