The research report summarizes the results of a project to assist in the development of a mix design procedure for partial depth cold in-place recycling (CIR) mixtures.
An asphalt pavement rehabilitation method, CIR involves mixing reclaimed asphalt pavement (RAP), water, and a recycling agent in place and without heat. During the construction of partial depth cold in-place recycling, one type of CIR, milling is done at depths of 50 to 100 mm, or two to four inches, with the resulting layer freuqently used as a base course.
In this project, researchers mixed RAP from Trunk Highways 23, 59, and 71, and County State Aid Highway 5 with emulsions CSS-1, HFMS-2s and HRMS-2p. After preparing specimens with a gyratory compactor and Marshall hammers, researchers tested the specimens for bulk specific gravity, maximum specific gravity and air voids. In addition, indirect tensile strength tests were used to evaluate the effects of changes in curing periods and compactive effort on CIR mixtures.
Researchers concluded that the asphalt content in the RAP affects the emulsion to be added in the CIR mixture; that emulsion HFMS-2p resulted in the lowest overall voids; and that the gyratory compactor produced the best specimens for testing and evaluation.