ILLINOIS' EXPERIENCE WITH A RECYCLED CONCRETE INLAY

Abstract

This paper describes a research project which evaluated the feasibility of recycling a deteriorated concrete pavement. A cracked and badly faulted 24-foot wide jointed reinforced concrete pavement was selected for the study. Originally constructed in 1964, the pavement cross-section consisted of 10 inches of concrete over six inches of aggregate subbase. A 27-foot wide inlay was constructed to take advantage of the bituminous shoulders that had been reconstructed in 1978. The two northbound lanes of the four lane project were constructed in 1986, and the two southbound lanes completed in 1987. The construction seauence consisted of removing the inner l 1/2 feet of each shoulder, breaking the pavement with a diesel pile driver, crushing the broken concrete, cement stabilizing the aggregate subbase in-pl ace to a depth of seven inches, and constructing a new 10-inch continuously reinforced concrete pavement. The recycled concrete mix contained both coarse and fine crushed concrete. Small amounts of natural sand and fly ash were added for workability. The crushed concrete met standard auality requirements with the exception of the sodium sulfate soundness test. The mix properties of the recycled concrete were comparable to those of a conventional concrete mix. The Illinois Department of Transportation is monitoring the long-term performance of the pavement. The feasibility of the recycling process and the cost savings potentially associated with such a process indicate that recycling deteriorated concrete pavements is yet another viable rehabilitative technique.