00473098

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http://onlinepubs.trb.org...1987/1106v1/1106v1-009.pdf

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

A pilot study was undertaken to provide alternate methods of rebuilding county and other secondary roads using phosphogypsum, a phosphate mining waste that is abundant in fertilizer-producing countries, as an aggregate and stabilizer. Current construction practice for some of these roads consists of mixing and further compacting the generally granular soil subgrade with fine-grained soils that are transported to the site. These mixtures tend to be largely affected by changes in the moisture regime. Several phosphogypsum-sand mixtures have been studied, mainly under California Bearing Ratio tests, as well as unconfined compression tests, to determine their engineering properties under different curing conditions, as well as to find useful design parameters. Both dihydrate and hemihydrate phosphogypsum were used throughout this investigation. Most of these mixtures yielded significant strength and bearing gains; however, some of them also became unstable when soaked. A rapid-curing cutback asphalt, RC-70, was added to the mixtures to decrease their moisture susceptibility. It was found that a very small percentage of RC-70 is required for specimens to develop such water resistance. Several alternatives that would perform acceptably when used in the construction of secondary roads are presented in this paper.

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 59-64

1987-8

Transportation Research Record

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

0309044545

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Figures (7) ; References (10) ; Tables (3)

California bearing ratio; Impacts; Mining; Properties of materials; Reconstruction; Secondary roads; Testing; Wastes; Water

Phosphogypsum

Construction; Environment; Geotechnology; Highways; Materials; I33: Other Materials used in Pavement Layers; I52: Construction of Pavements and Surfacings

TRIS, TRB

Sep 30 1987 12:00AM