A composition useful as an asphalt additive includes a plurality of substrate particles and a coating layer disposed on the particles, the coating layer including a solid elastomer. A method of producing an asphalt additive includes mixing an emulsion comprising an elastomer with a plurality of substrate particles. Another composition useful as an asphalt additive includes a plurality of substrate particles substantially coated with a first coating layer and a second coating layer, the first coating layer including a solid elastomer. An asphalt mix includes the asphalt additive composition, aggregate, and a binder.