Interlocking Prefabricated 3D-Printed Low-Carbon Concrete Wall Panels for Low-Income Housing Construction in South Africa 

South Africa lacks over 2.6 million government-subsidised low-income housing (LIH) units, which are exclusive to very low-income households. The LIH units are built with unreinforced conventional concrete blocks and burnt-clay bricks. The use of these materials in large volumes has a significant negative environmental impact. The production of cement, an ingredient of concrete, is energy- and carbon-intensive. The LIH units have very poor construction quality, which is both detrimental to residents and burdensome for the government due to very high maintenance costs. Furthermore, the thermal performance of conventional masonry walls of LIH units is poor, leading to residents’ discomfort.

Another challenge in South Africa is that 40 million tonnes of fly ash, a coal-fired power station by-product, are produced annually. Of this, 36 million tonnes end up in landfills, posing a significant pollution risk and occupying land that could serve other purposes.

This project aims to tackle the above challenges by developing a novel “3D-printed low-carbon concrete wall panel” system for the rapid construction of high-quality and sustainable LIH units using 3D-concrete-printing (3DCP) and geopolymer technologies. 3DCP is a new construction technology that reduces waste, time, and costs but enhances quality. Geopolymer utilises fly ash and does not contain any cement, thereby reducing carbon emissions by as much as 80%.