Investigation of Los Angeles value and alternate aggregate gradations in OGFC mixtures

• The tests include permeability, Cantabro loss, and breakdown in the lab and asphalt plant.
• In most cases, the high L.A. materials performed as well as the low L.A. material.
• Both low L.A. Abrasion and High L.A. aggregates exhibited significant breakdown in the field.
• Aggregate source played a key role in determining the Cantabro loss of OGFC mixtures.
• Field test sections for OGFC mixture using alternate gradations is highly recommended.

Open Graded Friction Course (OGFC) mixes with high air voids are mainly used to provide better service on the highway pavement during the rainy weather through draining water from the surface of the pavement. The objective of this study was to investigate performance characteristics of one low L.A. Abrasion aggregate compared to three high L.A. Abrasion aggregates as measured by various laboratory mix testing procedures to determine if overall OGFC mix performance was affected by an aggregate durability standpoint. In addition, three alternate aggregate gradations on the performance of OGFC mixtures were investigated. The main tests include permeability, Cantabro loss, and breakdown in the lab and asphalt plant of OGFC materials. The test results indicated that the high L.A. materials performed as well as the low L.A. material (Control) in most cases. In addition, various blends of similarly sized aggregates perform equally as well as the current South Carolina Department of Transportation (SCDOT) OGFC blend based on the limited laboratory testing conducted in this study. In the field testing, both the low L.A. Abrasion aggregate and high L.A. aggregates exhibited significant breakdown as measured from laboratory results of samples taken at various points in the production process as well as from visual observation during sampling. Constructing test sections using alternate gradations while maintaining desired OGFC mix properties is generally recommended.