1887

oa Civil Engineer in South Africa - Rapid weathering dolerites

 

Abstract

Six occurrences of dolerite exhibiting a rapid weathering phenomenon on exposure of the apparently fresh rock to the atmosphere are described. The weathering process takes place over a period of several months to years and is believed to result from swelling pressures generated during the hydration of constituent clay minerals of the smectite group. These clays, produced by a process of deuteric alteration, occur principally in the form of microfracture infillings spaced several millimetres apart in the rock material and / or as joint infill material in the rock mass. Engineering problems associated with these rocks and concerned mostly with the deterioration of crushed rock stockpiles are discussed. Use of two simple laboratory indicator tests, the ethylene glycol soak test and the slake durability test, to accelerate the breakdown of these rocks is described.

Ses voorkomste van doleriet waarin die rots vinnig verweer wanneer dit aan die atmosfeer blootgestel word, word beskryf. Die vetweringsproses vind oor 'n tydperk van verskeie maande tot selfs jare plaas en daar word geglo dat dit die gevolg is van sweldrukke wat ontstaan tydens die hidrasie van kleiminerale van die smektietgroep. Hierdie kleie, wat die gevolg is van 'n deuteriese veranderingsproses, kom hoofsaaklik voor as vulmateriaal van mikrobreuke wat etlike millimeter van mekaar in die rotsmateriaal gespasieer is, en / of as naatvulmateriaal in die rotsmassa. Geassosieerde ingenieursprobleme met hierdie gesteentes wat veral verband hou met die verswakking van gebreekte klip in voorraadhope word bespreek. Die gebruik van twee eenvoudige laboratoriumindikatortoetse om die verbrokkeling van die rotse te versnel, nl die etileen-glikolweektoets en die blusduursaamheidstoets, word beskryf.

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/content/civeng1/21/7/EJC24776
1979-07-01
2016-12-08
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