AGGREGATE TOUGHNESS / ABRASION RESISTANCE AND DURABILITY TESTS RELATED TO ASPHALT CONCRETE PERFORMANCE IN PAVEMENTS By
i DISCLAIMER The contents of this report reflect the views of the authors who are solely responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views and policies of the National Center for Asphalt Technology of Auburn University. This report does not constitute a standard, specification, or regulation. ii ABSTRACT Numerous tests have been developed to empirically characterize aggregate without, necessarily, a strong relationship with the performance of the final products incorporating these aggregates. This seems to be particularly true for aggregate " toughness and abrasion resistance " and " durability and soundness. " The purpose of this research was to identify and evaluate toughness/abrasion resistance and durability/soundness tests for characterizing aggregate used in asphalt concrete and to determine those test methods that best correlate with field performance. Based on a review of literature and specifications, laboratory tests for characterizing aggregate toughness/abrasion resistance and durability/soundness were selected. Sixteen aggregate sources with poor to good performance histories were identified for evaluation with the selected suite of tests. Performance histories of pavements containing these aggregates in asphalt concrete layers were established through personal contacts with state transportation agencies and performance evaluation questionnaires. Aggregate properties from laboratory tests were correlated with field performance. The Micro-Deval and magnesium sulfate soundness tests provide the best correlations with field performance of asphalt concrete, and are recommended for characterizing aggregate toughness/abrasion resistance and durability/soundness.
Investigation into the Use of Carbonate Coarse Aggregates in Alabama Concrete Pavements: Final Report
Carbonate coarse aggregates such as limestone and dolomite are not currently permitted in mainline concrete pavements in Alabama. However, up to 50% of the coarse aggregate in asphalt pavement surface courses may be carbonates. When siliceous aggregates must be imported for road construction, this situation often places concrete pavements at an economic disadvantage compared to asphalt pavements. A study sponsored by the Portland Cement Association – Southeast Region was conducted at The University of Alabama to investigate the possibility of reintroducing carbonate coarse aggregates for use in concrete pavements in Alabama. This report addresses concerns about friction loss following diamond grinding of concrete pavements containing carbonate coarse aggregates, how to best characterize the polishing resistance of coarse aggregates, and how to design and construct new pavements to minimize the need for diamond grinding. On each topic, a review of current practices, specifications, and research is presented, specification improvements suggested, and research needs identified.
ROADWAY MAINTENANCE EVALUATION USER'S MANUAL
The manual has been developed as a reference to be used in conjunction with a training school and a reference for personnel responsible for conducting the roadway visual survey. The visual evaluation method described in this manual consists of the utilization of two forms; one for flexible pavements and one for rigid pavements. Items recorded include location of the roadway being evaluated, an indication of the type, amount and degree of pavement distress, and an evaluation of the conditions of the shoulder, roadside and drainage features and traffic service items. Road roughness is measured by use of a Mays Meter whose output is converted to a serviceability index. Data from this evaluation can be used for maintenance management purposes.