In this paper are presented the results of field and laboratory investigations undertaken to determine the role that material variability, mix design factors, and other parameters play in the performance of recycled asphalt pavements on secondary roads. After the pertinent literature on the economics and procedures associated with various recycling methods was reviewed, a sampling program was developed to collect cores from existing pavements. This coring program was undertaken to evaluate the variability of the materials that form the asphalt pavements of county roads and city streets in Indiana. Statistical analyses of the data obtained on these cores showed that there is practical significance in the variation of parameters, such as asphalt content, aggregate gradation, and asphalt penetration, within a section of road, between county and city asphalt pavements, and among geographic regions in the state. Characterization of these materials allowed the author to simulate in the laboratory actual conditions such as hardness of the binder, gradations of aggregates andreclaimed asphalt pavement material, asphalt contents, and other properties of the recycled mix within the range of values measured from pavement core samples. The effects of these parameters were measured by means of the Marshall and resilient modulus tests. It was found that a stable and sound pavement can generally be obtained using cold-mix recycling techniques if normal reclaiming procedures are followed and regular asphalt emulsion binders are added.(A).
Abstract