3.0  PROPERTIES AND LOCATION OF ROAD BUILDING MATERIALS

 

The following section is dealing with the physical properties and their locations of the major rocks and their weathered derivatives which are used as road construction materials in Namibia. The different materials are classified according to their geological isotopic ages. As a basis for this classification the Geological Map of Namibia, 1980, 1:1.000.000 is used. Some simplifications are made in order to make the classification of rocks according to their road building properties simpler to understand for road builders and civil engineers [5].

The physical properties of road building materials in their geological context can only be given in a global, summarised form because too many variations and different parameters like gradings, Atterberg limits, construction techniques etc. do exist. A systematic evaluation of road pavements for paved and unpaved roads were undertaken in Dierks, Klaus: Technical Aspects for Appropriate Low-Volume Roads in Namibia, chapters 5 to 7 [6] in order to develop quality and cost optimised models and revised material specification on the basis of ' VOC' and acceptance and rejection criteria for a broad scope of roads all over Namibia.

In Namibia five main periods of lithogenic activity can be determined:

1. Vaalian to Lower Mokolian (+- 2.100 to +-1.500 Ma)

2. Upper Mokolian (+- 1.500 to +- 1.000 Ma)

3. Damara Orogenic Phase (+- 900 to 450 Ma)

4. Carboniferous to Lower Cretaceous (345 to 120 Ma)

5. Tertiary to Recent (from 65 Ma)

WB00823_.GIF (134 bytes)

[Table of Contents ]

forward.GIF (132 bytes)