00473102

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http://onlinepubs.trb.org...1987/1106v1/1106v1-013.pdf

https://scholar.google.co...alas&publication_year=1987

The occurrence of premature distress of a lime-stabilized, weathered basalt that was used in the construction of a strategic low-volume road in northeastern Botswana prompted a comprehensive investigation by the Roads Department. The main objectives of this investigation were to determine the probable causes and mechanisms of the unexpected base failures and to assess the overall structural integrity of the road. The main findings of the investigation, which included pavement and surface condition surveys, in situ and laboratory materials evaluations, and a petrographic study of the weathered base course aggregate are presented in this paper. A significant finding of the study was that although the weathered basalt satisfied the standard classification and strength criteria for a stabilized base, the pavement was not durable enough to retain its structural integrity in the project environment. Factors that contributed to this shortcoming included: (a) the presence of altered or secondary clay minerals in the aggregate in excess of the recommended critical limit for the project climate, and (b) the occurrence of carbonation of the lime, which resulted in apparent reversion of plasticity and a lack of significant strength development in the material. The major conclusion of the investigation is that special attention should be paid during the design process to the assessment of durability, including the mineralogical composition and carbonation potential, of weathered basaltic materials, which could significantly influence their in-service performance.

This paper appeared in Transportation Research Record N1106, Fourth International Conference on Low-Volume Roads, Volume 1. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

00490258

pp 89-102

1987-8

Transportation Research Record

International Conference on Low Volume Roads, 4th, 1987, Ithaca, New York, USA

0309044545

Print

Figures (13) ; Maps (1) ; References (21) ; Tables (8)

Basalt coarse aggregates; Base course (Pavements); Calcium oxide; Carbonation; Condition surveys; Durability; Failure analysis; Field tests; Geological surveying; Laboratory tests; Low volume roads; Mineralogy; Petrography; Structural analysis; Weathered rock

Design; Geotechnology; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I36: Aggregates

TRIS, TRB

Sep 30 1987 12:00AM