Performance of cold in-place recycling in Nevada

Abstract

In light of the increasing cost of hot-mix asphalt (HMA) mixtures and the limited availability of good materials, cold in-place recycling (CIR) offers an attractive alternative for rehabilitating asphalt pavements. Because of its limited performance history and the unavailability of a standard mix-design procedure, the use of CIR mixtures has been limited to low-and medium-volume roads. For more than a decade, many highway agencies have experimented with or used CIR mixtures and reported numerous successes. The Nevada Department of Transportation (NDOT) is currently using CIR on low- and medium-volume roads. The CIR layer is treated as a stabilized base course followed by a thin HMA overlay. As part of this program, NDOT developed a mix-design procedure based on the Hveem mix-design method to establish the optimum moisture and emulsion contents. The design procedure evaluates the moisture sensitivity of the CIR mixture and determines the need for lime treatment of the CIR mix. The basic concept of the mix design is to assess the ability of the CIR process in providing a flexible and stable mix that can withstand the combined action of traffic loads and environment. The designed CIR mixtures were implemented on three field projects and showed excellent performance, which led NDOT to construct additional CIR projects.