Incorporating tire rubber powder (crumb rubber) into asphalt enhances pavement durability, reduces noise, and supports circular economy goals. This guide outlines the technical process, benefits, and best practices for using rubber powder in asphalt mixtures.
1. Material Preparation
Rubber Powder Specifications:
Size: 0.5-2mm (80% passing 1mm sieve).
Purity: <0.1% steel/fiber content (ASTM D5644-01 standard).
Asphalt Binder: PG 64-22 or PG 70-28 modified with rubber powder (10-25% by weight of binder).
2. Mixing Process
Wet Process (Most common):
Pre-blend rubber powder with hot asphalt binder (160-190°C) for 45-60 minutes.
Add aggregates (stone, sand) and mix at 170-180°C.
Maintain viscosity below 3 Pa·s (ASTM D4402).
Dry Process:
Directly mix rubber powder (3-5% by total weight) with aggregates before adding binder.
Limited to small projects due to higher compaction challenges.
3. Key Applications
Rubberized Asphalt Concrete (RAC):
Reduces road noise by 5-10 dB (FHWA study).
Extends pavement lifespan by 30-50% compared to conventional asphalt.
Stress-Absorbing Membranes (SAMIs):
Apply rubber-modified binder as an interlayer to prevent reflective cracking.
4. Performance Advantages
Thermal Resistance: Reduces rutting at high temperatures (40-60°C).
Flexibility: Low-temperature cracking resistance (-20°C).
Sustainability: Replaces 10-20% of virgin bitumen, lowering CO₂ emissions by 15-30%.
5. Quality Control & Standards
Testing Protocols:
Softening Point (ASTM D36): ≥60°C.
Elastic Recovery (ASTM D6084): ≥60%.
Storage Stability (48h at 163°C): ΔSoften Point ≤2.5°C.
Field Application:
Layering temperature: 150-160°C.
Compaction density: ≥93% (AASHTO T 312).
6. Case Study: Arizona’s Rubberized Asphalt Program
Scale: Over 2,000 lane-miles paved since 2003.
Results:
40% reduction in maintenance costs.
25% longer service life than standard asphalt.
For technical specifications or project consultation, contact our asphalt modification experts.