Consolidation and Permeability of Two Compacted Schist Saprolites

Saprolites derived from a mica schist and a quartz schist from southwestern Nigeria are compacted at three energy levels, namely 0.6 MNm/m³, 1.1 MNm/m³, and 2.7 MNm/m³, and subjected to consolidation and permeability tests. Despite their high mica contents—25% and 30%, respectively—the saprolites attained fairly high maximum dry densities (1.68–2.04 t/m³). For each saprolite, increased compaction energy reduced compressibility appreciably but caused virtually no difference in permeability; the quartz schist saprolite being less compressible and less permeable than the mica schist saprolite. The compressibilities varied from low to very low while the saprolites have very low permeability for all the compaction energies. Comparison of the results of these tests on this mica schist saprolite with those of mica schist saprolites obtained from high horizons shows that the mica schist saprolite used in this study is better suited for use as subbase and fill material.