This report presents a study initiated in 1984 to develop specification guidelines and mix design recommendations and to obtain performance data on cold-mix recycling projects in Ohio. Future investment planning was the motivation for the Ohio Department of Transportation to consider cold-mix recycling of local roads as a maintenance alternative. Two mainline, low volume roads and one shoulder pavement were selected for this study. Documentation and evaluation of the projects are discussed generally in two parts. The first part includes the site selection criteria, pre-construction evaluation, mix designs, construction specifications and construction monitoring. The second part discusses performance evaluation through field inspection, data collection and laboratory evaluation of material properties.

This synthesis will be of interest to pavement designers, construction engineers, and others interested in economical methods for reconstructing or rehabilitating bituminous pavements. Information is provided on the processes and procedures used by a number of states to recycle asphalt pavements in place without application of heat. Since 1975 a growing number of state highway agencies have reconstructed or rehabilitated asphalt pavements by recycling the old pavement in place. This report of the Transportation Research Board describes the processes used for cold in-place recycling, including construction procedures, mix designs, mixture properties, performance, and specifications.

Cold recycling is a technically promising and cost effective method for improving distressed asphalt pavements. Unlike hot-mix recycling, cold recycling lacks extensive field and laboratory performance data. There is no widely accepted cold in-place recycling (CIR) mix design and testing standard available. This study attempts to generate useful field and laboratory data on pavements constructed with CIR mix and technique. Two field case studies are conducted. The testing of field cores and laboratory samples from these two field sites is conducted to address the existing and new methods for design and performance testing of CIR mixes in partial depth pavements. The laboratory tests include physical property testing (e.g., moisture content, gradation, air voids, emulsion, and aggregate properties) and performance-related testing (e.g., resistance to deformation, retained strength, rut, and fatigue). Relative performances of the CIR mixes from the two sites are analyzed.