MECHANICAL BEHAVIOR OF SAND AND FINES MIXTURES
Shear strength; Compressibility; Soil mixtures; Intrinsic Compression.
In the majority of engineering problems, soil is composed of different
proportions of coarse and fine particles whose mechanical behavior is different from
that of sand or pure clay. This study aims to determine both compressibility and strength
of mixtures composed by sand and fines from a Post-Barreiras sediment collected in
Natal, Rio Grande do Norte State. Sand-fines mixtures with varying fines contents of 0,
30, 50, 75 and 100% were prepared. The mechanical characterization was performed by
means of edometric compression and direct shear tests. It was observed that the
compressibility parameters vary with fines content and depend on the applied stress and
sample initial conditions. The transition fines content determined by edometric tests
varies between 10% and 30%. It was possible to determine a single Intrinsic
Compression Line (ICL) for the materials studied. Direct shear tests resulted in friction
angles ranging from 30° to 38°. The addition of 30% fines increases the mixture
strength in comparison with sand at the maximum void index. For higher fine contents,
the maximum shear stress decreases until a value close to that observed for the fine
matrix.