In the last several years (since 1984) oregon has used cold in-place recycling (cir) techniques as one alternative to conventional practices for the rehabilitation of asphalt concrete (ac) pavements. All cir efforts have consisted of partial-depth (ac-surface) recycling on low-volume roads--generally less than 2, 000 average daily traffic--with good success on most projects. Projects have also been completed on county roads and u.S. Forest service roads using this technique. In most cases, the recycled mat is treated with a sand seal or a chip seal. Construction costs for this operation are on the order of $1.70 To $2.10 Per square yard compared with $2.75 To $4.00 Persquare yard for a conventional 2-in. Ac overlay. Because of the success of the initial projects that were cold recycled in 1984 to 1985, the oregon state highway division (oshd) and oregon state university (osu) have studied cold in-place recycling in detail since 1986. One purpose of the studies by oshd and osu has been to develop a better understanding of the performance and economics of the cold in-place recycled pavements. A brief overview of the cir construction anddesign process, the performance to date of selected projects, and an economic evaluation of cir as an alternative to other rehabilitation techniques are provided. Significant findings include (a) the current state-of-the-art in recycling equipment allows for efficient and economic recycling practices; (b) over 75% of the cir projects in oregon since 1984 were rated fair or better in 1984 to 1989; and (c)cir can provice significant savings realized through conservation of energy and costly construction materials. On the basis of the results of the joint study to date, it appears that cir is a viable rehabilitation alternative for low-volume roads. Hence, using the cir concept on higher-volume roads (including interstates) is now proposed. This paper appears in transportation research record no. 1291, Fifth international conference on low-volume roads, may 19-23, 1991, raleigh, north carolina, volume 2.
Abstract