Abstract
With a rise in virgin aggregate consumption, the use of recycled materials has become an attractive solution in earthwork and pavement construction. An understanding of the behavior and characteristics of recycled materials is necessary before they are used in practice. In this study, the behavior of recycled concrete aggregate (RCA) during compaction in a 3-ft-diameter cross-linked polyethylene bin was examined. The main objectives of this experiment were to (a) determine the applicability of the nuclear gauge and time domain reflectometry for measuring the dry density and moisture content of RCA, (b) measure the stiffness of the RCA with a portable falling weight deflectometer and GeoGauge, (c) estimate the compaction-induced lateral pressures of the RCA, and (d) assess the variation in moisture content, dry density, and stiffness of the RCA over a 2-month postcompaction period. Measurements were taken immediately after each lift was compacted and again over the postcompaction period. Highlights of the study findings include (a) the nuclear gauge provided higher moisture content values than the oven-measured values, which suggested a need for moisture offsets; (b) the zone of influence must be considered in the interpretation of portable falling weight deflectometer and GeoGauge moduli; and (c) compaction significantly increased the locked-in lateral stress from its normally consolidated at-rest value. In the postcompaction phase of the experiment, there was evidence that additional pozzolanic reaction occurred in the RCA, followed by shrinkage cracks.
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