Oregon has used cold in-place recycling (cir) techniques since 1984 as one alternative to conventional asphalt concrete pavement rehabilitation practices. The initial success of the early cir projects(1984 and 1985) prompted a joint research effort in 1986 between the oregon state highway division and oregon state university. This effort, continued in 1988, has focused on developing improved mix design procedures and construction guidelines for cold in-place recycling. One of the goals of the study was to develop a sample preparationprocedure for cold recycled mixtures; the samples were to be used for mix design purposes. To validate the procedure, selected mix properties of field cores were compared with those of laboratory-prepared samples. The field and laboratory studies, their results, and a comparison of their results are described. Also, the cir mix properties are compared with those of conventional hot mixes. Significant findings include (a) laboratory samples can be prepared at void contents similar to those found in the field; (b) laboratory sample mix property test results generally compare well with those of the field cores; and (c) limited comparisons showed that cold in-place recycled mixtures generally have greater moduli and fatigue lives than conventional hot mixes at similar void contents. This paper appears in transportation research record no. 1317, Asphalt mixtures: design, testing, and evaluation 1991.
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