Construction World December 2023

Left: To avoid concrete spillage on the road, AfriSam never overloads its readymix trucks. Right: Using slag as a replacement for Portland cement significantly reduced the carbon footprint of concrete.

of recycled aggregates up to 10% of the concrete mix. “This means the careful sorting of concrete material in demolitions, to provide an acceptable quality of concrete,” he says. Water re-use in the readymix sector has become a pillar of responsible practice, especially in a water-scarce country like South Africa, explains Dawneerangen. At AfriSam readymix plants, considerable volumes of water are required for rinsing out the 6 m 3 cement mixing trucks. This water is recycled by channeling the runoff into a series of settling ponds, so that the cleaner water at the end of the process can be used for cleaning again. Rainwater is also harvested for the production of concrete to reduce the volume of municipal water drawn by the plants. “Even in our mix designs, we endeavour to use as little water as possible – using admixtures to achieve better long term performance,” he says. “The accuracy of our measuring systems also ensures that no water goes to waste.” The careful management of waste concrete also contributes to sustainability by promoting a circular economy. AfriSam makes every effort to avoid concrete being rejected at site, by having systems and equipment to ensure accuracy of mixes. Where it is unavoidable to return readymix from site to the plant, however, there is accommodation for this. “We have designated areas at our quarries where our trucks can dump waste concrete,” he says. “After hardening, we can use this concrete in the production of gravel material such as G5, where the recycled concrete actually enhances the product.” In the readymix transportation phase, there is risk of spillage which can be a safety issue as well as an environmental incident. To avoid this, AfriSam makes sure never to overload its readymix trucks, as a steep uphill gradient can cause concrete to pour over the lip of an over-filled drum. The company also goes the extra mile by placing covers on its truck chutes, preventing any residue from dripping onto the site or road as the truck leaves a site. “Scheduling and logistics are important in managing Systems and equipment ensure accuracy of mixes, reducing waste and return loads.

Ensuring durability starts with quality materials that comply with the relevant specifications. waste, as the time on the road has a direct effect on concrete workability and performance when it gets to site,” he says. “With our sizeable fleets, our GPS and truck-tracking systems, combined with the right admixtures, we can ensure that a workable, on-spec product is delivered every time.” For any readymix operator, a mechanical breakdown of a truck brings commercial and environmental implications – including not just letting down a customer and delaying a construction project, but the waste of energy, resources and concrete. AfriSam’s skilled logistics department arranges regular servicing to ensure vehicles are well maintained to be fuel efficient and reliable. Considering the design life of concrete structures, Dawneerangen highlights that the concrete’s durability plays a central role in reducing the structure’s carbon footprint. “If a concrete structure can meet or even exceed its design life – with as little maintenance as possible – it minimises the resources and energy that must be invested in it,” he says. “A good example of this is roadworks, where any failure of the structure incurs the cost of repair and associated disruption, both involving extra carbon emissions.” Ensuring durability starts with quality materials that comply with the relevant specifications, he says, from the cement to the aggregates and additives. Once the right materials are sourced from reputable suppliers, it is essential to design and implement the appropriate concrete mixes. “With AfriSam’s legacy and experience, we are well placed to provide customers with these materials and these mixes, suitable for the different applications and environments in which they will be used,” he concludes. 

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22 nd Best Projects Awards 2023