Since concrete is the most important building material used in construction industry globally, its production has become expensive over the years due to an increase in demand for housing. This has led to an increase in prices of both aggregates and cement. One of the development goals of Kenya’s big four agenda is to provide affordable housing to all people especially in slums and shanties, this may be seamlessly achieved by provision of quality and affordable building materials such as aggregates.

With this rising need for infrastructural development and goals towards this development already set, it means a much more quantity of concrete of good quality will be required at an economical and environmentally friendly manner. A steady supply of components of concrete that is fine aggregates, course aggregate and cement has ensued over the past times, with natural river sand been majorly used as the fine aggregate in concrete mixes.

But in pursuit of development we must be careful not to bring about environmental degradation. Of late natural river sand has proven to be scarce and expensive commodity, due to its depletion from mining in river beds. Quarry dust however as earlier established has been considered a waste product of rock crushing activities, attributing to its fine quality which qualifies for the size specification of fine aggregates, perhaps it could match its applicability as a fine aggregate in terms of compressive and flexural strength to those contributed by natural river sand in concrete mixes.

Additionally, alongside promotion of economical and environmental friendly construction techniques, recycling of waste generated from construction and demolition has not been emphasized in the industry. Additionally ballast is obtained from quarrying processes that generate noise, vibrations and dust, leading to degradation of land value, and reduction of ground water quality (W.Kindiga, November, 2017).

Hence the need to do so by finding out the probability of replacement of ballast coarse aggregate with recycled waste concrete, crushed to the appropriate size to be fit for use as a coarse aggregate.

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