In an effort to address this environmental crisis, the national government of South Africa has started a research initiative to use the mechanically chipped biomass of water-thirsty invading alien plants (IAP’s) as a substitute for sand and stone as aggregate in conventional concrete.

The clearing of these IAP’s from water catchment areas can contribute to producing more sustainable wood chip cement, or “noncrete” building materials, ensuring water security, restoring natural ecosystems and creating labour intensive jobs in impoverished communities.

The innovative use of IAP biomass in construction offers significant carbon sequestration opportunities, while also addressing the increasing demand for dignified and affordable housing across South Africa, which has the highest income inequality in the world.

A recent study has shown that there is enough invading alien woodchip to meet the current housing shortfall three-time over in South Africa. Combined with a low-cement binder, this wood chip cement is three times more fire-proof than conventional building materials in South Africa such as cement or clay bricks and has double the thermal insulating properties at half of the weight of conventional concrete.

The proposed structural system as a viable alternative construction method for housing demonstrates how structural geometry can significantly reduce resource consumption and enable the use of local and more sustainable yet structurally adequate building material such as “noncrete.” Combined with structurally-informed fabrication techniques, this system demonstrates the potential of providing safer and more dignified housing alternatives in an affordable and sustainable manner.

The barrel-vaulted roof consists of self-supporting bricks, which can be constructed on-site with minimal amount of formwork and without requiring expert labour. More importantly, the geometry of the roof and the interlocking system of the bricks eliminate the use of steel reinforcement. The weight of each brick has also been optimised to be handled easily by both male and female workers.

The arch-profiled floors have shown that it can drastically reduce the amount of material compared to conventional slabs in buildings. The lightweight falsework and shuttering of the formwork system can be fabricated using local grasses and invasive reeds by local basket weavers. Such a system not only further reduces the overall environmental impact of the building as well as the construction process, but also supports market-driven demand for sustaining local tradition and craftsmanship.

During an interview done by ECC team with Juney Lee @juney.lee from ETH Zurich, he mentioned: “In South Africa, there is an abundance of invasive alien plants that consume a lot of water from the natural ecosystem. For this project, we are using them as aggregate in place of stone and sand that is typically used in conventional concrete. So in a way, we are using something that is locally available yet ecologically harmful in South Africa and turning it into an ingredient for a more sustainable version of concrete. The invasive alien plants are first chipped into small pieces of wood, which is then mixed with water and binder to create the bio-concrete…”

Juney continues: “We’ve been working closely with our colleagues in South Africa. We are currently testing different ways of fabricating these self-supporting bricks with complex geometry. From the context of ETH Zurich, we can experiment a lot with digital fabrication methods such as 3D printing, which was used to generate some of the prototypes in the exhibition. On the other hand, we are also investigating how to fabricate them in much more humble and cost-effective ways with locally available resources in the South African context.“

The building industry is responsible for 40% of global resource consumption, over 35% of waste generated worldwide and nearly 40% of human-caused CO2 equivalent emissions each year.

The global population is expected to increase by 2.1 billion people over the next 30 years, and it is simply not possible to continue building the way we do today if we want to reduce greenhouse gas emissions, slow the depletion of natural resources and minimize waste production.

With nearly three quarters of a typical building’s embodied energy being attributed to its structural mass, a sustainable future of the building industry ultimately requires a drastic shift in how structural systems of buildings are designed, fabricated, and constructed.

Make sure to check the exhibition of Block Research Group (BRG) @blockresearchgroup with Department of Environment, Forestry and Fisheries – Republic of South Africa and Noncrete PTY and @ethzurich at Palazzo Mora Room 5. The interview done with Juney Lee could be seen on IGTV of @ecc_italy