Proposal of a Full-Scale Destructive Test Method to Assess Integrity of Natural Armourstone

Abstract

The quality of materials used in coastal and river structures is of primary importance for protection against the hydraulic action of waves and currents. The ability of natural armourstone blocks not to display significant breakage along weakness planes and cracks is defined as “integrity”. In an initial research survey designed to address materials quality issues, where professionals identified integrity as “essential”. However, it remains poorly understood. Methods for assessing block integrity have been documented and this research focuses on full-scale destructive tests. A preliminary field study established experimentally that the documented methods display poor repeatability and limited correlations with each other. In addition, full-scale impact testing displays a significant variability due to limited control of the test conditions. Consequently, a full-scale splitting test was developed to provide a better control of test conditions. To evaluate its ability (i) to differentiate different type of discontinuities affecting the sample and (ii) to offer a correlation with effective loads, a field study was set up, which is currently under progress. The results were studied by plotting the changes in the mass distribution. The form of the mass reduction distribution before and after energy is applied and the shift to smaller sizes provides a powerful analytical tool to study the breakage processes. Comparing the mass reduction results of the full-scale splitting test and the mass reduction results of routine handling in the quarry provides a means of relating breakage in a standardized test to potential breakage in handling operations and in long-term service. Such a calibration process has the potential to authenticate a test method whose results can subsequently be used to predict the performance of the important class of construction materials.