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The geotechnical properties of lateritic and non-lateritic soils of southeastern Nigeria and their evaluation for road construction

  • E. G. Akpokodje
Article

Abstract

The soils within the entire length of the Port Harcourt—Enugu expressway consist of (1) concretionary laterite gravels (2) non-lateritic tropical sandy/clayey soils which are gravelly in some places and (3) silty to fat clays formed from shales. The particle size distribution and the plasticity of the majority of the soils indicate that by standard acceptance specifications they are unsuitable for base materials. Field compaction results revealed that the relative compaction of 95–100% can be easily achieved in the field using 10–12 ton vibratory rollers.

Although the pavement materials used for the expressway are inferior under conventional standards, mostly isolated rather than widespread pavement failures have so far occurred. Such failures are presumed to be more related to poor field compaction rather than the inferior quality of the construction materials. Where the troublesome weathered shale forms the subgrade, severe pavement failure usually occurs.

Keywords

Optimum Moisture Content Particle Size Distribution Curve Relative Compaction Laboratory Compaction Vibratory Roller 

Propriétés géotechniques de sols latéritiques et non-latéritiques utilisés en construction routière dans le sud du Nigeria

Résumé

Les sols que l'on rencontre sur l'ensemble du trajet de la route express Port Harcourt-Enugu sont:
  1. 1.

    des graveleux latéritiques

     
  2. 2.

    des sols tropicaux sablo-argileux non latéritiques, parfois graveleux

     
  3. 3.

    argiles ou argiles limoneuses dérivées de schistes.

     

La granularité et la plasticité de ces sols les rendent inutilisables en tant que couches de base si l'on suit les spécifications en vigueur. Mais les mesures de compacité in situ ont atteint 95–100% de l'O.P.M. en utilisant des compacteurs vibrants de 10 à 12 tonnes.

Bien que ces matériaux soient donc hors spécification on n'a constaté jusqu'à présent que des dégradations très localisées des couches de chaussées. Elles sont d'ailleurs probablement dues à des défauts locaux de compactage.

Mais dans les zones où la couche de forme est faite en schistes altérés, on constate généralement des dégradations importantes des couches de chaussée.

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References

  1. AMERICAN SOCIETY FOR TESTING AND MATERIALS (1975): Special procedures for testing soil and Rock for Engineering Purposes.Special Technical Publication, p. 479. 5th ed.Google Scholar
  2. GIDIGASU M.D. (1975): The behaviour of laterite materials in the roadway structure. (A review)Buil. Road Res. Inst. Ghana, Current Rep. 8: p. 37.Google Scholar
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Copyright information

© International Assocaition of Engineering Geology 1986

Authors and Affiliations

  • E. G. Akpokodje
    • 1
  1. 1.Department of GeologyUniversity of Port HarcourtPort HarcourtNigeria

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