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Shifting sand: Why we’re running out of aggregate

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Abstract

With global demand for building sand tripling in the last 20 years, unregulated sand mining is decimating rivers and coastlines in the developing world, enabled by political corruption and “sand mafias”. This article outlines the contours of the problem and records new attempts to find sustainable substitutes for use in concrete. As our “sand budget” heads into the red, there are even calls to begin designing concrete out as a default construction material.

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... Mining of river aggregates (sand, gravel, etc.) is usually carried out for its further industrial use and processing (e.g., cement production, glass industry, construction, etc.) [6,7]; roads has gained popularity thanks to the speed of order delivery, and the ability to quickly adapt to customer needs, by providing just-in-time deliveries, reducing storage space, and increasing cash flow. Transport (the distance between production and consumption) nowadays represents an assessed factor in determining environmental sustainability. ...
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Purpose Over dependence on river/sea sand as building material has impacted the environment negatively. However, laterite, which is an environment-friendly indigenous building material in sub-Saharan Africa, has been less exploited as a suitable alternative. This paper aims to ascertain the optimum cement–laterite mix proportion at which laterite can be stabilized for production of walling units. Design/methodology/approach Using an experimental method, laterite was collected from three borrow pit sites. Sieve analysis was performed to determine the particle size distribution. Also, the degree of workability of the cement–laterite mix was ascertained using slump test. Compressive strengths were determined at cement stabilization percentages of 3%, 7% and 10% on 12 cubes of100 mm cast and cured for 14 and 28 days, respectively. Findings The results showed that the lateritic soil investigated, achieves its optimum strength in 28 days of curing, at a stabilization level of 10%. An average compressive strength of 2.41 N/mm2, which is 20.5% greater than the target strength, was achieved. Practical implications To meet the desired compressive strength of alternative walling units while achieving environmental sustainability and efficiency in production, cement stabilization of lateritic soils should become a recommended practice by built environment professionals in sub-Saharan Africa. Originality/value This paper is one of the first research works that attempts to determine the optimum level at which the abundant sub-Saharan laterite can be chemically stabilized for the production of non-load bearing walling units. This research promotes an environment-friendly alternative building material to sea sand, river sand and off-shore sand.
Sand and Sustainability: Finding New Solutions for Environmental Governance of Global Sand Resources. GRID-Geneva, United Nations Environment Programme
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