Density Tests Above Zero Air Voids Line

TO compute the degree of saturation, S, one must have the results from tests for water content, wet unit weight, and specific gravity. Each has inherent variability, which results in a variability in S. This variability results in a percentage of S plotting above the zero air voids line (ZAVL). After first showing that Gaussian normal distributions apply to the test results, the writer proposes typical low, average, and high values for test and soil plus test variability and then uses both numerical and analytical methods to predict the percent of S above the ZAVL. He then presents the density test results from three large cohesive fills to support the analytical study. Knowing the percent of tests above the ZAVL may provide the engineer with an additional quality check of a cohesive fill. Arbitrarily rejecting all tests above the ZAVL will distort the perceived character of the fill, which could result in action detrimental to the engineering behavior of the fill and might provide the basis for a claim for extra compensation by the contractor.