Construction World April 2017

Waste at the facility that will be recycled.

recycled concrete into the G5, giving us a good mixture of decomposed material and returned concrete,” Docrat says. “During our G5 run to produce the material for sub-base layers in road making, we began testing by trickle-feeding a small portion of returned material into the G5, and found that it worked well.” Quality The first trial was on the Gauteng Freeway Improvement Project’s N1 extension, where AfriSam provided G5 for a few runs and the contractor gave it the thumbs-up; that was where the success of the idea really started to prove itself, according to Docrat. As with all AfriSam products, quality control and rigourous testing is constantly required to ensure that it is fit-for-purpose. The material is sampled first from the production stockpile. Then, once it is in the set-back stockpile, it is fully tested for compliance with the final specification for G5 product. “Customers also rely on the fact that all AfriSam products comply with the South African Bureau of Standards’ COLTO (Com- mittee of Land Transport Officials) material grading specifications,” he says. “Our G5 product containing the recycled concrete has passed all the necessary quality hur- dles under the SABS requirements.” Paving the way Another successful application for the returned concrete at AfriSam’s Jukskei Quarry has been the paving of many parts of the readymix site. A concerted effort is underway at the quarry’s readymix division, where a new plant is in place, to construct pedestrian walkways and to pave open areas. This is likely to consume a portion of the returned concrete. “We have already been able to pave large areas of the readymix site,” he says. “This is possible when there is a return during the day, when there are people available to manage and supervise the pouring of returned concrete in the appropriate areas.”

vary according to the economic climate and times of year. But he is confident that the amount of returned concrete that will be recycled into saleable AfriSam product could comprise up to 60% of the total concrete returned to the readymix site. The recycling process, he says, will certainly make for a more sustainable environment; while at the same time make a contribution toward offsetting the costs that returned concrete place on the business. Preserving the planet AfriSam’s Jukskei Quarry, one of the company’s 17 aggregate plant sites nationwide, produces concrete aggregate, crusher sand, base and sub-base material. As part of AfriSam’s corporate commitment to conserve the planet, it directs significant effort towards environmental stewardship. As a result of ongoing research, the company has developed a cement product – Eco Building Cement – that has a carbon footprint of 453 g/kg, which is almost half of the world average of 890 g/kg. 

This process begins with the preparation of areas to be paved, so that wet concrete can be poured into the waiting formwork and immediately leveled, with expansion joints left between the slabs. It is a well-organised process that en- sures an attractive and functional end-re- sult, he says. Environment Docrat highlights the importance of an environmentally friendly response to the issue of returned concrete, as there are no dumping facilities which accept this kind or quantity of waste. Recycling also means no slush around the plant, less potential for contamination, and a smaller carbon footprint. “Our Environmental Management Programme requires that we achieve a certain level of recycling in our waste management strategies, and this breakthrough in recycling concrete is certainly a contribution to our performance in this regard,” he says. The actual amount of concrete recycled each month is dependent on sales, which

The final product after it has been recycled and blended.

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CONSTRUCTION WORLD APRIL 2017