Statistically-Based Specifications for Crushing Resistance of Gravel Surface Course for the Crawlerway at Kennedy Space Center

Point load strength index testing performed according to ASTM D 5731 was used to evaluate the crushing resistance of potential sources of gravel for the Crawlerway at the Kennedy Space Center. A specification was developed that uses statistical inference to compare the point load strength of a gravel sample from a proposed source to the strength of samples of the existing gravel. The approach was developed to prevent gravel that is too weak or too variable from being used on the Crawlerway, while still allowing the existing gravel to pass. During the course of the project, it was also found that there is a moderate correlation between the results of LA Abrasion tests and the point load strength index, which suggests that gravel that is resistant to crushing is also less likely to be easily abraded.