Introduction
Construction aggregate is normally defined as hard, granular materials usually suitable for use either on their own or with the addition of cement, lime or a bituminous binder in construction (Ademila, 2019). Its important applications include concrete, mortar, road stone, asphalt, railway ballast, drainage courses and bulk fill. To ensure that construction aggregates are fit for purpose and meet the requirements of the end uses, it is important to have an understanding of the mineralogy of the source rocks, production processes, the different standards for different uses and test methods used to evaluate their suitability. Aggregates are expected to be durable and resistant from both environmental and man-made degradation.
In Botswana, compilation of aggregate resources was initiated by the Department of Geological Survey (DGS) (Ntsimanyana, 1995; Kreimer et al., 1990; Lekula, et al., 2015). The Department focused its efforts in the Eastern part (Southern, Central, Kgatleng and North Eastern Districts) of the country where the demand for aggregates was high (Kreimer et al., 1990). Other parts including the Kgalagadi District, Gantsi District, Ngamiland, Boteti and Chobe District were however, excluded. The previous attempt to compile aggregate information also lacked information on aggregate quality in relation to their suitability for different applications (Kreimer et al., 1990). Therefore, the main aim of this report is to explore for aggregate source rocks in Botswana, compile a database for all aggregate deposits, review different geological settings in which aggregate source rocks occur and produce an industrial minerals map to show the distribution of industrial minerals around the country. The assessment will not only guide the construction industry and aggregate exploration companies; it will also guide land use planning which could help avoid resource sterilization in the future.
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