Utilization of kimberlite tailings as aggregates in concrete - strength and selected durability properties
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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.153
Utilization of kimberlite tailings as aggregates in concrete – strength and selected durability properties Mike Otieno and Esina Ndoro School of Civil and Environmental Engineering, University of the Witwatersrand, Johannesburg
Abstract
The feasibility of using kimberlite tailings as aggregates in concrete was assessed. Compressive strength and selected durability tests were carried out on concretes made using various replacement levels (0, 40, 60 and 100%) fine and/or coarse blended crushed andesite and kimberlite tailings as aggregates. A w/b ratio of 0.50 and a CEM I 52.5R were used. The results show that the kimberlite tailings as aggregates have a relatively high water demand which was manifested as a reduction in workability of the fresh concretes with kimberlite tailings as a proportion of either fine and/or coarse aggregates. The results also showed that the use of the kimberlite tailings as a proportion of either fine or coarse aggregates in concrete resulted in a decrease in both compressive strength and durability properties viz water sorptivity and oxygen permeability. This was partly attributed to the low workability of the concretes which is known to limit the degree of compaction of fresh concrete. It is envisaged that careful concrete mix proportioning including the use of admixtures and prewetting of the aggregates can be used to offset the negative effects of high water demand of the kimberlite aggregates. Corresponding author: Mike Otieno ([email protected])
INTRODUCTION As the demand for concrete continues to increase, more research is now being carried out on non-conventional (or alternative) concrete-making materials including binders, aggregates and admixtures. These studies assess the feasibility of using nonconventional materials to make concrete with respect to various properties including strength, durability and sustainability [1]. This has led to the explorative utilisation of industrial waste materials such as slag, tyres and mine tailings as aggregate in concrete.
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Waste materials produced from the mining and extraction of metal, industrial mineral and energy resources constitute one of the largest waste streams on Earth. South Africa’s mining industry has been active since the mid-1800s. Mine tailings are the waste by-product of several extractive processes of mineral ore [2], and are typically stored in lined or unlined dam with an earth-fill embankment [1]. Vast stockpiles of unprocessed and re-processed mine tailings are currently available at various mining sites in South Africa and pose problems for disposal [3]. Utilisation of tailings as input materials in the production of concrete will allow for a sustainable disposal potion and the conservation of conventional virgi
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