COMPARISON TESTS OF AUTOMATED EQUIPMENT FOR ANALYZING AGGREGATE GRADATION

A number of automated test machines are commercially available for rapidly determining the grain size distribution of unbound aggregates. Designed to provide a faster alternative to standard sieve analyses, these machines capture and analyze digital images of the aggregate particles to determine gradation. Five of these test machines were evaluated for accuracy and performance using fifteen select samples of aggregate with different size, shape, and mineral characteristics. In this paper, several key issues in evaluating these machines are considered, including their accuracy when compared to standard sieve analyses.