Hydraulic Conductivity of Fly Ash-Amended Mine Tailings
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- 作者：Sultan A. Alhomair ; Mohammad H. Gorakhki…
- 关键词：Binder ; Fly ash ; Hydraulic conductivity ; Mine tailings
- 刊名：Geotechnical and Geological Engineering
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：35
- 期：1
- 页码：243-261
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Terrestrial Pollution; Waste Management/Waste Technology; Civil Engineering;
- 出版者：Springer International Publishing
- ISSN：1573-1529
- 卷排序：35
文摘
The objective of this study was to evaluate the effect of fly ash addition on hydraulic conductivity (k) of mine tailings. Mine tailings used in this study were categorized as synthetic tailings and natural tailings; two synthetic tailings were developed via blending commercially-available soils and natural tailings were collected from a garnet mine located in the U.S. Two fly ashes were used that had sufficient calcium oxide (CaO) content (17 and 18.9 %) to generate pozzolanic activity. Hydraulic conductivity was measured on pure tailings and fly ash-amended tailings in flexible-wall permeameters. Fly ash was added to mine tailings to constitute 10 % dry mass of the mixture, and specimens were cured for 7 and 28 days. The influence of fly ash-amendment on k of mine tailings was attributed to (1) molding water content and (2) plasticity of the mine tailings. Tailings that classified as low-plasticity silts with clay contents less than 15 % exhibited a decrease in k when amended with fly ash and prepared wet of optimum water content (wopt). Tailings that classified as low-plasticity clay exhibited a one-order magnitude increase in k with addition of fly ash for materials prepared dry or near wopt. The decrease in k for silty tailings was attributed to formation of cementitious bonds that obstructed flow paths, whereas the increase in k for clayey tailings was attributed to agglomeration of clay particles and an overall increase in average pore size. The results also indicated that the effect of curing time on k is more pronounced during the early stages of curing (≤7 days), as there was negligible difference between k for 7 and 28-days cured specimens.