Construction World December 2021

AfriSam has evolved its operations in many ways to be good neighbours.

Opposite (from left): Over the past 20 years, AfriSam has reduced the volume of carbon dioxide per tonne of cement by about 30%; AfriSam’s technological advances have included the use of specialised grinding aids, adding these to the milling process; AfriSam has about 20 000 different concrete mixes on its database; and The 2010 Soccer World Cup led to a spike in infrastructure development.

when mineral rights became vested in the state, and quarries fell under the same regulations as large mines. “Urban growth in South African also meant that our quarries – located in what were quite rural areas – now felt the encroachment of industrial and residential areas,” says Bhoora. “In line with our philosophy of respecting people and planet, we have evolved our operations in many ways – to be good neighbours.” This has affected many aspects of work, from drilling and blasting to loading and hauling, and even working hours. Innovations have had to address key areas of concern to the social and natural environment, including dust control, noise abatement and vibration control. The proximity to living areas is exemplified by the position of it Jukskei quarry, for instance; once a remote site between Johannesburg and Pretoria, the quarry now has the Mall of Africa, light industry and residential suburbs on its doorstep. Being classified as mining operations, quarries have also been required to develop and apply Social and Labour Plans. AfriSam has aligned its policies and practices accordingly, and often goes beyond compliance to ensure that it maintains a resilient social-licence-to-operate among stakeholders. Greener readymix AfriSam’s readymix operation, the other pillar of its vertically integrated structure, has seen considerable evolution in the last 20 years, he says – not least as a result of the environmental sustainability imperative. “In the same way that we have evolved our cement for lower carbon emissions, so our readymix products have also followed this path – using less clinker and cement,” he says. “One of the impacts of this is less water in the mix to lubricate the particles, so our aggregates have to be smoother and have better workability.” To manage the void content in the mix, a more continuous grading of aggregate is necessary. Developing and applying technology to achieve all these outcomes has therefore been vital to drive AfriSam’s objectives of performance, efficiencies and sustainability. Spoilt for choice Bhoora notes the diversity in concrete strengths and mixes that has been developed over two decades. When he joined the sector some 30 years ago, 20 to 25 MPa was regarded as adequate for most building and construction applications. “Today, it is common for us to receive requests for strengths of 60 to 80 MPa, and we recently were asked to supply concrete specified to 110 MPa for basement pillars,” he says. “Combining our expert skill sets with the latest technologies, AfriSam has about 20 000 different concrete mixes on our database.” In the short time since the millennium, the world of cement, aggregate and concrete has covered considerable ground – with AfriSam often leading the charge to a greener future. 

mechanically or chemically activating our additives,” he notes. “This allows us to achieve much higher reactivity from our extenders, so that we can extend further still. For the past couple of years, AfriSam has also been working on changing the mineralogy of clinker to make it more reactive.” Grinding aids The company’s technological advances have included the use of specialised grinding aids, adding these in the milling process. Using surface tension, having as its ultimate task the prevention of cement particle re-agglomeration during and after the milling process, these additives help to make material more flowable and easier to break down. These are specific to the different extenders used in the manufacturing process. “We also enhance the strength of our cements with additives like these, helping with cement hydration and strength development,” he says. “These strength enhancers or admixtures can improve early strength by 10-15%. The result is less clinker per cubic metre of concrete and so less energy is required and less carbon dioxide is emitted.” Conserving power Thermal energy has traditionally been a major cost in cement making, and AfriSam has over the past two decades explored alternative fuels extensively. The burning of used tyres in an environmentally controlled manner, for instance, has been implemented to some extent, while it is hoped that greater government facilitation could increase these levels. Carbon sludge is also being burnt, replacing up to 10% of coal-based energy. “We have invested in a multi-channel, high-efficiency burner at one of our cement plants and plan to install another, which can accommodate five or six different fuels at a time,” says Meyer. “This not just allows alternative fuels to be used, but also reduces nitrous oxide emissions.” He highlights the technological developments in dosing and metering systems in cement plants which have become more accurate and more controllable. These in turn achieve better energy efficiency, by not exceeding the energy requirements necessary for chemical reactions. “The life of the burning zone refractories in our kilns have also been improved, allowing kilns to run continuously for longer,” he says. “By running our kilns more reliably through our AfriSam Way maintenance approach, we have doubled the life of kiln refractories – giving us more uptime.” Changing face of quarrying The past two decades have also seen considerable change in the readymix and aggregate sectors, where AfriSam has long been among the leaders in the local market. Construction Materials Executive Avi Bhoora notes that a significant shift was

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20 th Best Project Awards 2021