Evaluation of the specification for flat and elongated particles for use in hot mix asphalt in Connecticut.

PDFTech ReportCT-2305-F-13-10SPR-2305Hot mix paving mixturesSpecificationsRecommendationsMix designCoarse aggregatesShear stressParticlesConnecticutConnecticut. Dept. of TransportationZinke, ScottMahoney, JamesMorison, KellyClement, StephenConnecticut Transportation InstituteUnited States. Federal Highway AdministrationUS Transportation CollectionThis research was conducted to determine if the specification for flat and elongated aggregatesfor use in Hot-Mix Asphalt (HMA) in Connecticut can be reasonably achieved. Currently, theConnDOT specification allows for no more than 10 percent flat and elongated particles utilizing a3:1 ratio. It has been speculated that this specification may not be achievable by most HMAproducers in Connecticut. The research team evaluated specifications from numerous regionalstate agencies for comparison with the ConnDOT specification. The research team also sampledaggregates from 15 sources which produce HMA for ConnDOT. 3/8-inch and 1/2-inch aggregateswere sampled from each source, and flat and elongated tests were conducted on both sizeaggregates from all 15 sources. This totaled 30 aggregate samples tested from which only sixpassed the 10 percent maximum at the 3:1 ratio. Recommendations are made to change thespecification to reflect achievable percentages of aggregates which are not flat and elongated. Itis the opinion of the research team that this percentage should be not more than 10 percent flatand elongated particles by weight utilizing a 5:1 caliper ratio, ASTM D4791, Method B