The Council for Scientific and Industrial Research (CSIR) has partnered with nonprofit organisation Use-It Waste Beneficiation and building solutions company Key Bricks to develop a prototype green building block made from construction waste material that can be used to build low-cost houses.

The innovation was funded through the Department of Science, Technology and Innovation (DSTI) Circular Economy Demonstration Fund, which is aimed at demonstrating proven circular economy interventions, including technologies, innovative process improvements and social innovations that have not yet achieved scale or impact in South Africa.

The partner organisations demonstrated to DSTI officials on April 11 the process of manufacturing the innovative building blocks, starting from the crushing of waste glass and building rubble to the finished block and, finally, the low-cost housing structure.

The green block contains 70% recycled waste content, including crushed waste glass, as well as construction and demolition waste. The block itself is 100% recyclable.

The bricks are designed to interlock, requiring no cement between layers, allowing for the building to be easily constructed with limited building experience and, if needed, the structure can later be deconstructed and the blocks reused at another location. Each block features internal hollows, which, when stacked, create channels for installation of electrical and water pipes, reducing the need to cut grooves, also known as chasing, thereby ensuring that the blocks remain intact.

The blocks came from the need to find local markets for waste glass and building rubble in KwaZulu-Natal, explain CSIR senior researcher in sustainability economics and waste Aubrey Muswema, Use-it MD Belinda Putterill and Key Bricks CEO Matt Olivier.

“It’s not viable to transport waste glass from KZN to Gauteng for recycling; the margins on this are just too slim, resulting in a lot of this waste remaining uncollected and impacting the environment. We needed to find ways to use glass locally in KZN,” says Putterill.

Cities, towns and villages across the country are also plagued with the illegal dumping of building rubble in open spaces, and these blocks use crushed waste glass, and construction and demolition waste, thereby reducing the need for conventional virgin materials.

The block is cost-effective, and also saves construction time and requires minimal labour and building experience. The top structure was put up by relatively unskilled labour from foundation stage to the roof within seven days, which is only possible because of the interlocking nature of the faceted blocks, says Muswema.

By using waste as a resource, this interlocking block can unlock new business opportunities in the construction industry. Local businesses and value chains can benefit from the potential to generate additional revenue streams.