About DuPont™ Elvaloy® RET Reactive Elastomeric Terpolymer

Product Description

Elvaloy® RET is a reactive elastomeric terpolymer with the chemical designation EGA (ethylene/glycidyl/acrylate) -- the first DuPont polymer specifically designed for modifying asphalt. It is mixed into asphalt cement in the form of solid pellets as the asphalt is being prepared for shipment to a hot mix plant. The pellets melt under high temperature and react with the asphalt to form a stable, homogenous binder material known as a polymer modified asphalt (PMA).

Well-designed PMAs incorporating Elvaloy® RET can add years of service life to a roadway and help delay major maintenance requirements. This is evidenced in test results and field experience showing that asphalts made with the DuPont EGA terpolymer deliver superior resistance to stripping, rutting, cracking and fatigue versus unmodified asphalts, and versus asphalts made with traditional modifiers such as styrene-butadiene-styrene (SBS) block copolymers. (Note: For more discussion and comparison of properties and test results, read Preventing Asphalt Failures.)

Comparison with SBS Copolymers

SBS copolymers consist of block segments of styrene monomer units and butadiene rubber monomer units. Each block segment can consist of many monomer units. The most common form used in asphalt modification is a linear styrene-butadiene-styrene structure, but radial types are also available.

SBS polymers are physically dispersed in asphalt, but do not chemically react with the asphalt. Keeping a consistent dispersion often requires extra care and attention, and this can be especially difficult if there is any project delay in using of the material.

Also, the butadiene midblock in SBS is unsaturated -- which means it will oxidize in the pavement. This "sacrificial aging" will initially help the asphalt resist aging, but once the polymer is oxidized, the viscoelastic property benefits of the polymer modification are gone.

Elvaloy® RET is quite different. The ethylene terpolymer consists of an ethylene backbone modified with two types of functional groups. A glycidyl group is present and gives the polymer its epoxy-like reactive properties. The reaction with asphalt assures a permanent and uniform dispersion that won't separate over time, even if there are project delays.

Resists Aging and Oxidation

The acrylate functional groups in Elvaloy® RET add flexibility and elastomeric properties to the PMA binder. Since the ethylene backbone is saturated, it is relatively resistant to oxidation or aging versus butadiene-based materials.

Elvaloy® RET is compatible with a wide range of asphalts. Care is taken to match grades and formulation strengths of Elvaloy® RET to meet the needs of each asphalt.