Boiled absorption and volume of permeable voids testing (ASTM C642) may be required for structures that need enhanced liquid-tightness or resistance to aggressive environmental exposures. The test is sometimes used to provide an overall indication of the quality of the shotcrete mixture, particularly in dry-mix. However, many factors, including admixtures and aggregate, as well as shotcrete placing, can affect the porosity of shotcrete, so it should not be considered an absolute measure of shotcrete quality. When required, the mean average of tests on three specimens from a test panel, or from in-place shotcrete, should be less than or equal to the specified boiled absorption and/or specified volume of permeable voids limits at the specified test age with no single test greater than the specified boiled absorption plus 1%.