Nature of Fines Produced in Aggregate Processing

Abstract

The fines produced in a three‐part laboratory test series developed to simulate crushing, handling, and placement of roadway aggregates were compared to fines determined from field records for six aggregate sources in Alaska. These sources were associated with projects that had final fines contents in the roadway structure that exceeded the amount allowed by the state of Alaska. A comparison of the laboratory and field results indicates that the test series may overestimate the quantity of fines likely to be produced under normal field conditions. The nature and quantity of fines created in the laboratory test series were analyzed in order to determine their contribution to the frost action susceptibility of a representative base course aggregate. The fines produced are predominantly in the coarse‐silt size range (0.02–0.074 mm). Current frost action susceptibility theories suggest that these fines alone should not render the base course aggregate frost susceptible, but fines present before crushing in combination with those produced in processing may prove to be detrimental to roadway structure performance.