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Some geotechnical properties of residual mica schist derived subgrade and fill materials in the Ilesha area, Nigeria

  • E. A. Mesida
Article

Abstract

Fine grained micaceous soils are known to be relatively difficult to densify by compaction, and they may pose subsequent stability problems to pavement structures constructed over them if appropriate caution is not exercised during the construction period. The texture, consistency. compaction and CBR characteristics of the mica schist derived lateritic soils in the Ilesha area were studied for a critical evaluation of the long term performance of soils which have been used as borrow materials in the construction of stretches of the Ife-Akure highway. X-ray diffraction studies confirm that the main clay mineral present is kaolinite, but it is associated with various amounts of illite, montmorillonite and chlorite. Densification by compaction was observed to be relatively inhibited when the maximum dry density values are compared with those of other lateritic soils occurring in the same locality. Soaked CBR values are low, ranging from 6% to 14% only. Textural considerations disqualify the soils as borrow material, but surprisingly, the consistency limit values make them tolerable.

Keywords

Montmorillonite Nigeria California Bearing Ratio Pelitic Schist Micaceous Mineral 

Résumé

On sait que les sols micacés et à grain fin, sont relativement difficiles à compacter, et ils peuvent poses ultérieurement des problèmes d'instabilité pour les structures de chaussées construites au-dessus si on ne prend pas les précautions nécessaires pendant les périodes de construction. L'auteur a étudié la granularité, la compacité etles caractéristiques CBR des terres latéritiques dérivées d'un mica schise de la région d'ilesha pour l'évaluation critique des performances à long terme des sols utilisés comme matériaux d'emprunt pour la construction de certaines sections de la grande route Ife—Akure. Les études faites par diffraction montrent que le minéral argileux principal présent est le kaolin, mais qu'il s'associe a des quantités variables d'illite, de montmorillonite et de chlorite. Quand on compare les valeurs maximum de compacité sèche avec celles des autres sols latéritiques qui se trouvent dans la même région, on constate que la compacité est relativement mauvaise. Les valeurs de CBR saturé sont basses, et vont de 6% à 14% seulement. Les considérations granulométriques et de texture rendent ces sols impropres à l'utilisation comme matériau d'emprunt alors que les valeurs de la plasticité les classent dans les sols assez bons.

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Copyright information

© International Assocaition of Engineering Geology 1986

Authors and Affiliations

  • E. A. Mesida
    • 1
  1. 1.Department of GeologyUniversity of IfeIle-IfeNigeria

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