Refinement and Validation of the Hydraulic Fracture Test

This report describes the results of recent research efforts to improve the test. The hydraulic fracture index has been replaced by a model that predicts freeze-thaw test dilation as a function of the distribution of particle mass retained on various sieves after testing. This model was developed using data obtained from freeze-thaw and hydraulic fracture testing of 18 quarried carbonate and gravel aggregate sources, and the resulting correlation is exceptional (r-squared = 0.98). In addition, a large test chamber was developed to allow testing of aggregate samples five times larger than the original small chamber, thereby allowing aggregate durability characterization with a single test run. It is believed that the hydraulic fracture test is now ready for more broad-based validation testing and eventual widespread acceptance and implementation as an accurate screening tool for concrete aggregate freeze-thaw durability. Report describing the results of recent improvements to the Washington Hydraulic Fracture Test for concrete aggregate freeze-thaw durability. The test is believed to now be ready for validation testing and eventual wide-spread acceptance and implementation as an accurate tool.