In 1986 and 1987, the Illinois Department of Transportation constructed an experimental recycling project on Interstate 57 in southern Illinois. A badly D-cracked, 7-in-thick continuously reinforced concrete pavement was recycled into a 16-in-thick, full-depth asphaltconcrete inlay. The southbound lanes, designated Section A, were completely constructed with virgin aggregate. The northbound lanes were constructed in two sections: Section B, with a recycled concrete aggregate/virgin aggregate blend binder and a virgin aggregate surface, and Section C, with a recycled concrete aggregate binder and a virgin aggregate surface. The recycling process and the performance ofa full-depth asphalt concrete pavement containing recycled concreteaggregate are described. Certain materials problems were noted. Therecycled concrete aggregate failed the sodium sulfate soundness test. A consistent bulk specific gravity was difficult to obtain due tovariable concrete mortar percentages. Nuclear gauge asphalt contents of mixtures containing recycled concrete aggregate were unreliable, thereby requiring the use of extractions. Ride quality and friction tests, visual distress surveys, rut depth measurements, and deflection testing with a falling weight deflectometer have been conductedsince construction. Cores were taken and signs of moderate to severe moisture damage were found in Section A, but little or no moisturedamage was found in Sections B and C. Core tensile strengths and backcalculated asphalt concrete moduli were considerably lower in Section A than in Sections B and C. The data suggested that these differences were attributable to the presence of moisture damage in Section A.
Abstract