Construction and demolition ( C & D ) waste constitutes up to 22 % by mass in landfills across South Africa .
dump the waste , why not set up a processing plant , stockpile the waste and then upscale it to create a saleable product .”
Encouraging acceptance
One of the big challenges when it comes to C & D waste recycling is uses for the final product . In the UK and Europe , some tenders specify that a certain percentage of aggregates used must come from recycling . However , in South Africa the opposite is often the case , with public sector tenders often specifying only virgin material and zero secondary material .
According to Barnes , secondary material is used quite extensively in the private sector , particularly when it comes to development of roads and big parking lots within shopping centres , for example , and contractors are keen to start using more of this material in roads . “ The government sectors , being the largest end users , are still risk averse , however ,” she adds , “ and because we don ’ t have long-term performance indicators for South Africa based on the material that we generate , there ’ ll be a bit of a delay in terms of changing this policy .”
“ We are working on publishing case studies that will inform industry and government about the usefulness of secondary materials , and how they are actually being used ,” Barnes continues , “ as well as demonstrating the performance of those materials from a structural or strength point of view and a financial point of view . I know that green procurement is on the agenda for many government structures , from the local to the national .”
“ I know the Department of Human Settlements has been debating and discussing potential policy changes related to green procurement in construction tenders . What we ’ re also hoping to do , particularly when it comes to the roads , is to produce national guidelines for the application of builders ’ rubble in roads , which will then develop into formal specifications and standards .”
Barnes points out that the only requirement in place currently relating to the use of secondary materials in construction is if the developers or clients want a green building rating – then , one of the options is to include secondary materials in the structure . Unfortunately , the scoring for this option is quite low , so while most companies will target the waste diversion from landfill , they don ’ t often target the inclusion of that same material or other such material in their structures . This is also influenced by the widespread industry perception that secondary materials are lower quality options .
However , there are potential problems with the concept of requiring a certain percentage of recycled material in projects unless it is properly handled . Barnes explains : “ I was at a Global Aggregates Information Network ( GAIN ) meeting in 2016 , and it was interesting to hear the Australian perspective . They found that in some ways specifying a certain recycled content within a construction project sometimes resulted in companies having to truck in secondary materials from quite some distance away . This made the environmental footprint worse than if they ’ d just used the virgin materials that were almost right there on site .”
“ Whether secondary materials are a viable alternative or not depends a lot on the construction activity and the planning strategies of the area that you ’ re looking at ,” she adds . “ You need high enough construction activity within a relatively old , built-up environment because you need both demolition and construction to generate the waste needed to include in new projects . So it ’ s very location specific , and wouldn ’ t work across the board in South Africa to require a certain percentage of recycled material to be used .”
Govender agrees that the acceptance of recycled material as a viable option for construction is an issue that needs to be addressed . “ If you test the sand that comes out of a C & D waste recycling plant , it will compete head-to-head with crusher sand , and the benefit is that your fines are out , so
26 _ QUARRY SA | MAY 2017