A laboratory evaluation of rubber-asphalt paving mixtures : final report.

PDFTech ReportResearch Report No. 79Research Project No. 72-10B(B)Louisiana HPR 1(11)Laboratory testsAsphalt rubberMix designPavingAdditivesAggregate mixturesPhysical propertiesAlternatives analysisBindersBituminous mixturesMarshall testGyratory testing machinesLouisianaLouisiana. Department of Highways. Research and Development SectionCarey, Donald E.Louisiana. Department of Highways. Research and Development SectionUnited States. Federal Highway AdministrationUS Transportation CollectionThe primary objective of this study was to evaluate rubber additive asphalt and its aggregate mixtures in the laboratory with respect to their physical characteristics.Results obtained on the physical properties of the rubberized asphalt binder were compared to those of the original, untreated asphalt. The data indicate that an acceptable binder can be expected provided the quantity of rubber is closely controlled. Indications of a non-homogeneous composition were apparent for a few of the rubber additives.Bituminous mixtures were molded in t he laboratory using the mechanical Marshall Hammer and also the Gyratory Compactor. The Marshall method of mix design was used in arriving at an optimum asphalt content. The gyratory compaction was intended to simulate traffic conditions and to provide a measure of the performance of the mixes with and without rubber. The results obtained on the physical testing of various compacted mixes indicate that the optimum asphalt content of a mix could be slightly increased when rubber is incorporated into the asphalt cement due to the resulting increased viscosity. With few exceptions, an increase in stability and a decrease in flow values are attained at the same asphalt content when rubberized cement is employed