Serji Amirkhanian

Performance Characteristics Comparisons of Various Asphalt Mixture Technologies

A laboratory investigation was carried out to study the effects of various compaction technologies on moisture susceptibility, rutting resistance, and fatigue characteristics of various asphalt mixtures. The methodologies used in this study included three technologies such as common hot mix asphalt (HMA), warm mix (WMA), and half-warm mix asphalt (HWMA) technologies. In addition, in terms of WMA and HWMA mixtures, a foaming technology was used to produce the samples. The experimental design for WMA and HWMA included one aggregate moisture contents (� 0.5 % by weight of the dry mass of the aggregate), three lime contents (0 %, 1 % and 2 % lime by weight of dry aggregate), and 2 % foaming water content. For HMA, 1 % lime content and completely dried aggregate were used. Three aggregate sources (designated as A, B, and C) and one PG 64-22 binder were used in this study. A total of 9 Superpave mix designs and 21 mixtures were completed. A total of 84 indirect tensile strength (ITS) samples, 126 asphalt pavement analyzer (APA) samples, and 30 fatigue beams were tested in this research. The major properties such as gyration number, ITS, tensile strength ratio (TSR), rut depth, deformation, toughness, as well as fatigue life were measured and computed for all mixtures. The test results indicated that various compaction technologies would slightly affect the Superpave mix design and obviously have an influence on gyration number, ITS values, rut depth, flow, toughness, and fatigue life of various mixtures regardless of aggregate source and lime content. In addition, the aggregate source significantly affected the ITS and rutting resistance in this study.

Assessment of Recycled Asphalt Paving Unit Cost Risk: A Case Analysis

The majority of pavements in the United States are made of asphalt materials. Many of these pavements are getting old and they require some form of rehabilitation. In many cases, recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) can be utilized to create a pavement system while saving money by conserving natural resources. There are four major asphalt production cost categories including materials, plant production, trucking, and field construction. In general, the materials are the most expensive category, in many cases up to about 70% of the cost to produce HMA mixtures. Several thousands of records of various field projects from 2008 to 2013 were obtained from South Carolina Department of Transportation (SC DOT) and all of the mixtures containing RAP or RAS were recorded and analyzed. The main objective of this study was to compare the upper quantiles of the unit cost between two groups of asphalt pavement mixes containing different percentages of aged binder using a Harrell-Davis estimator of the quantiles. In most cases, the asphalt mixes containing more than 15% aged binder actually appear to have a negative effect on cost predictability at higher quantiles.