Material properties of coal-tar emulsion sealers

Coal-tar emulsion sealers are used to protect hot-mix asphalt pavements from damage due to the spillage of petroleum-based materials. This paper contains the results of a study, which has field tests and laboratory tests, concerning the effect of various amounts of aggregate, temperature variations, a polymer additive, and aging on the material properties of coal-tar emulsion mixtures. The material properties tests included thermal expansion, creep stiffness test, and by measuring tensile strength, the stress-strain relationships. The study results indicate that the thermal expansion of the mixtures increased with increasing amounts of coal-tar emulsion; however, this effect was slightly reduced with the addition of a polymer additive. Creep stiffness values increased with age and increasing amounts of aggregate in the mixture. The results of the stress-strain evaluation were not consistent. Increased amounts of aggregate, lower temperatures, and decreased amounts of polymer generally resulted in greater stress levels being achieved prior to failure.