Cracking Performance of Fiber-Reinforced High-RAP Asphalt Mixtures Using IDEAL-CT

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Pavement Technology

Background:

• High reclaimed asphalt pavement (RAP) use in asphalt mixtures enhances sustainability by reducing virgin material demand.
• Increased RAP content can lead to higher mixture stiffness and reduced cracking tolerance, posing a challenge for pavement durability.

Purpose of the Study:

• To evaluate the effectiveness of para-aramid fibers in improving the intermediate-temperature cracking resistance of high-RAP hot-mix asphalt.
• To investigate the influence of different fiber treatments (wax-coated, emulsion-treated) and dosages on cracking performance.

Main Methods:

• Utilized the IDEAL-CT test to assess cracking resistance of asphalt mixtures with varying RAP contents (15%, 25%, 40%).
• Incorporated two types of para-aramid fibers at dosages of 0.05%, 0.10%, and 0.15% by total mixture weight.
• Analyzed the impact of fiber addition on the CTIndex, a measure of cracking resistance.

Main Results:

• Fiber effectiveness was significantly influenced by RAP content, fiber treatment, and dosage.
• The 25% RAP mixture demonstrated the most substantial improvement in cracking resistance with fiber addition.
• Specific fiber types and dosages yielded significant improvements in CTIndex for 15% and 25% RAP mixtures, while results for 40% RAP were inconclusive due to variability.

Conclusions:

• Para-aramid fibers show potential for enhancing laboratory cracking resistance in high-RAP asphalt mixtures.
• The optimal fiber dosage is mixture-specific and not uniform across all RAP content levels.
• Further research including rutting, fatigue, aging, workability analysis, and field validation is recommended for practical implementation.