Asphalt Modifiers

Type General Purpose or Use Generic Examples
Filler Fill voids and therefore reduce optimum asphalt content
Meet aggregate gradation specifications
Increase stability
Improve the asphalt cement-aggregate bond
Mineral filler
crusher fines
lime
portland cement
fly ash
Carbon black
Extender Substituted for a portion of asphalt cement (typically between 20 – 35 % by weight of total asphalt binder) to decrease the amount of asphalt cement required Sulfur
Lignin
Rubber Increase HMA stiffness at high service temperatures
Increase HMA elasticity at medium service temperatures to resist fatigue cracking
Decrease HMA stiffness at low temperatures to resist thermal cracking
(see Figure 2)
Natural latex
Synthetic latex
(e.g., Polychloroprene latex)
Block copolymer
(e.g., Styrene-butadiene-styrene (SBS))
Reclaimed rubber
(e.g., crumb rubber from old tires)
Plastic Polyethylene/polypropylene
Ethylene acrylate copolymer
Ethyl-vinyl-acetate (EVA)
Polyvinyl chloride (PVC)
Ethylene propylene or EPDM
Polyolefins
Rubber-Plastic Combinations Blends of rubber and plastic
Fiber Natural:
Asbestos
Rock wool
Manufactured:
Polypropylene
Polyester
Fiberglass
Mineral
Cellulose
Oxidant Increase HMA stiffness after the HMA is placed. Manganese salts
Antioxidant Increase the durability of HMA mixtures by retarding their oxidation Lead compounds
Carbon
Calcium salts
Hydrocarbon Restore aged asphalt cements to current specifications
Increase HMA stiffness in general
Recycling and rejuvenating oils
Hard and natural asphalts
Antistripping Agents Minimize stripping of asphalt cement from aggregates Amines
Lime
Waste Materials Replace aggregate or asphalt volume with a cheaper waste product Roofing shingles
Recycled tires
Glass