Kansas has many miles of thermally cracked roads primarily in the western one-half of the State. Rehabilitation with conventional hot mix asphalt overlays and hot recycling have not given the service life expected before the existing cracks reflect through the pavement. Since 1986, the Kansas Department of Transportation has been utilizing cold in-place recycling (CIR) with an emulsified asphalt as an additive as a cost effective alternative for rehabilitation of thermally cracked low volume pavements. Field performance of the final product appears to have more variation than desirable with an expected life of three to five years. The results of a two year study indicate that the material properties of the locally available aggregates are poor which results in low strength of the CIR mixes. In addition, the in-place air voids of the wearing surface were high and had an adverse effect on the performance of CIR mixes.

Significant use of cold in-place recycling (CIR) has occurred in Oregon since 1984 as an alternative to other rehabilitation techniques or to the reconstruction of distressed asphalt concrete (AC) pavements. Due to the initial success of the projects cold recycled during 1984-85, the Oregon Department of Transportation (ODOT) and Oregon State University (OSU) undertook, in 1986, an intensive study to investigate cold inplace recycling. The objectives of this study were to: 1. develop an improved mix design procedure for cold in-place recycled pavements, 2. evaluate the structural contribution of the cold recycled pavements, and 3. develop improved construction guidelines and specifications for these pavements. Presented in this thesis are two papers summarizing the efforts and advancements made to achieve the first two objectives. Also included is a paper that evaluates the repeatability of two test methods which were, in part, used to evaluate the structural contribution of cold recycled pavements.

Cold in-place recycling (CIR) is a process in which 3 to 4 inches of the existing asphalt pavement layers are pulverized, mixed with a recycling agent, and repaved in place. It provides agencies with cost-effective and environmentally friendly pavement maintenance and rehabilitation options for aged asphalt pavements. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 569: Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling compiles and documents information regarding the current state of practice on how CIR and cold central plant recycling (CCPR) technologies are selected, designed, constructed, and evaluated by state departments of transportation (DOTs).