Triaxial tests have been carried out on unconventional fills. The shear strengths of gap-graded fills, with 15 and 30% of large particles in a fine matrix of sand, were compared with the matrix alone at a range of relative densities. It was found that when present at 30%, the large particles provide additional strength, whereas at 15%, they have an adverse effect. Possible mechanisms for these phenomena are discussed. Strength enhancement was still available when the large particles were of poor quality, friable limestone. These laboratory trials suggest that a more flexible specification for fill could lead to significant economies, but further tests will be requiredfor confirmation. This paper appears in transportation research record no. 1309, Geotechnical engineering 1991.
Abstract