New TU Graz Lab Develops Sustainable Concrete from Residual and Waste Materials

Residue-based geopolymers, such as those being further developed in the latest CD lab at TU Graz, could replace cement-based concrete in the future, especially in corrosion-prone application environments such as wastewater systems or biowaste facilities. Photo courtesy of Lunghammer – TU Graz.

Graz University of Technology (TU Graz) (Graz, Austria) has launched a new project to produce sustainably produced concrete mixtures from mineral residues and waste materials that could partially replace Portland cement-based concrete in the future, especially in application environments prone to corrosion such as sewage systems, biowaste plants, and tunnel drainage systems.

The project is led by Cyrill Grengg from TU Graz’s Institute of Applied Geosciences and head of the Christian Doppler (CD) Laboratory for waste-based geopolymer construction materials in the CO2-neutral circular economy. Grengg’s project is supported by eight key corporate partners, all of whom see potential in the use of building rubble, slag, metallurgical gravel, mineral wood, or ash for more environmentally friendly and resistant concrete.

With the opening of the CD lab on March 3, seven years of research will now be conducted with the eight corporate partners, with the largest funding body being the Federal Ministry of Labour and Economy (BMAW).

“The large number of participating companies from various sectors shows the great interest in greater resource efficiency and sustainability,” says BMAW Minister Martin Kocher. “Building material from residual and waste materials not only brings economic benefits, but also helps to reduce the burden on the environment. The know-how researched here can be the basis for many other innovations.”

Inorganic, industrial secondary raw materials such as slag and ash, as well as residual materials such as mineral wood and clay-rich demolition materials, are further processed in the CD lab. There they are combined with carbon-rich waste materials such as (waste) oils, biomass residues, or organic fibers, depending on demand and intended use. The resulting geopolymer offers comparable material properties to conventional Portland cement, along with better corrosion resistance and reduced consumption of resources.

“Chemically, the geopolymer is something completely different from Portland cement, but the physical properties are very similar or even better in some cases,” says Grengg.

Grengg sees great potential in geopolymers, especially in their resistance to (bio)chemical corrosion. While Portland cement is widely used in construction, it is susceptible to corrosion from wind, weather, and other environmental influences such as (bio-)chemically aggressive wastewater from sewage systems and treatment plants. In addition, the production of building materials is responsible for about 9% of all greenhouse gas emissions generated worldwide.

When worldwide costs caused by corrosion are considered, along with the amount of residual and waste materials produced, Gregg sees the recycling of these materials into geopolymers as a goal that is not only achievable, but one that makes economic and ecological sense.

“Today, large amounts of the residues and wastes used in the CD lab are landfilled, and only a small part is recycled,” says Grengg. “We want to take these materials from landfills and integrate them into a CO2-neutral recycling economy.”

Source: TU Graz,