Gypsum in saline and non-saline road bases: effects and limits derived fr0m long-term road experiments in Namibia

Show simple item record

dc.contributor.author Netterberg, F.
dc.date.accessioned 2021-11-02T09:24:35Z
dc.date.available 2021-11-02T09:24:35Z
dc.date.issued 2021
dc.description Papers presented virtually at the 39th International Southern African Transport Conference on 05 -07 July 2021
dc.description.abstract In parts of Namibia, Botswana and South Africa the only economically available road construction materials often contain excessive amounts of highly soluble salts such as NaCl (common table salt) and/or gypsum (CaSO4•2H2O) and fresh water for compaction is scarce. The Lüderitz and Haalenberg full-scale, long-term road experiments were therefore constructed in 1976 in the Namib Desert in Namibia in order to find ways of successfully using highly saline and gypseous materials as road pavement base course and of using seawater for the compaction of all layers. In this paper only those aspects concerning gypsum are presented. The experiments included a total of eight sections of G3 quality crushed stone bases with 2 – 20% added gypsum and two of G4 calcrete base with 5% (in comparison with the then permitted limit of 3,5%), in addition to their natural gypsum contents of 0,2 and 0,3% respectively, all under a 19 mm Cape seal surfacing. These experiments were monitored both during and soon after construction as well as for any long-term effects over a period of 36 years from 1976 until 2012. During this period the experiment only received two rejuvenation sprays and a minor amount of slurrying, edge patching, crack sealing and shoulder regravelling. For a 30-year design life and a capacity of at least 1,0M E80 under a 19 mm Cape seal, gypsum contents of up to 10% can be permitted in a G3 and up to at least 5% in a calcrete G4 base in this arid environment and probably in most of the southern African arid and semiarid zone.
dc.format.extent 21 pages
dc.format.medium PDF
dc.identifier.uri http://hdl.handle.net/2263/82369
dc.language.iso en
dc.publisher Southern African Transport Conference 2021
dc.rights Southern African Transport Conference 2021
dc.title Gypsum in saline and non-saline road bases: effects and limits derived fr0m long-term road experiments in Namibia
dc.type Article


Files in this item

This item appears in the following Collection(s)

Show simple item record