What are Asphalt Additives?

Bitumen additives are materials added in small amounts to asphalt binders or mixes to improve their properties. Some key additive categories include modifiers, anti-strip agents, lubricity enhancers, and recycled asphalt pavement (RAP) boosters. Modifiers are usually polymers that enhance the physical hardening characteristics and high temperature performance of the asphalt. Anti-strip agents help maximize the adhesion between aggregate and binder. Lubricity enhancers address issues with low-friction binders containing high percentages of recyclate. RAP boosters assist recycled materials by restoring lost properties from aged binders.

Modifier Additives

Polymer modifiers are one of the most common additive types used to enhance the properties of asphalt cement. They function by forming a "three-dimensional network structure" within the asphalt binder after being blended in. This network structure strengthens the binder and improves its elastic response to traffic loads and temperature variations. Some popular polymer additives include styrene-butadiene-styrene (SBS), styrene-butadiene rubber (SBR), ethylene-vinyl acetate (EVA), and polyphosphoric acid (PPA). SBS is widely used for its ability to significantly boost rutting resistance and temperature susceptibility of the binder.

Anti-Strip Additives

Another important category is Asphalt Additives which are designed to maximize adhesion between the asphalt binder and aggregate surface. This bond is critical for keeping pavement layers intact under stresses from traffic and climate. Common anti-strip options work by maintaining a waterproof bond line or by creating a physical barrier against moisture damage. Typical functional anti-strip agents include amines, portland cement, hydrated lime, and polysulfide polymers. These promote stronger binder-aggregate bonding through chemical and mechanical means. Proper anti-strip selection and dosage can help prevent premature pavement failures from moisture infiltration.

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