12 June 2025
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Story University of the Free State
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Photo Supplied
Collaborative innovation in action: Researchers from the University of the Free State’s Green Concrete Lab have partnered with the University of Johannesburg to advance 3D printing technologies using sustainable concrete materials.
Pictured (from left): Dr Hossein Naghizadeh, Senior Lecturer in Engineering Sciences at UFS, and Refilwe Lediga, Concrete Printing Research Expert in the Department of Civil Engineering Technology at UJ.
In an ambitious and interdisciplinary effort to address today’s Grand Challenges, researchers at the University of the Free State (UFS) are exploring how nature’s oldest life forms – stromatolites – can inspire cutting-edge innovations in industrial ecology and marine conservation. Drawing from biomimicry, 3D printing, and microbial engineering, their work showcases the convergence of ecological insight with modern technology.
“One such example is replicating the structures of stromatolites – some of the earliest evidence of life - using green cement and 3D printing, the latest technology in industrial ecology,” explains Dr Jacques Maritz, Head of the Unit of Engineering Sciences at UFS.
Ancient structures, modern science
Stromatolites are layered microbial formations created by ancient cyanobacteria and date back over 3.5 billion years. These living fossils, found in fossil records and rare modern environments like Shark Bay in Australia, grow through a combination of photosynthesis, sediment trapping, and calcium carbonate precipitation. Not only do they support biodiversity, but they also play a vital role in natural carbon sequestration.
UFS researchers are harnessing the lessons from these ancient formations to address urgent environmental challenges. In particular,
Dr Yolandi Schoeman, Senior Lecturer at the Centre for Biogeochemistry, is leading efforts to cultivate hybrid stromatolites in controlled environments, using microbial consortia grown on 3D-printed scaffolds.
“At UFS, we are reimagining stromatolite formation through both artificial structural replication and biological cultivation, bridging industrial ecology and microbial engineering to address modern environmental challenges,” says Dr Schoeman.
Ecological engineering for reef restoration
The rapid decline of marine biodiversity and the degradation of natural reef ecosystems have prompted ecological engineers to develop innovative solutions. At the UFS Green Concrete Lab, researchers are pioneering the design of artificial reefs using 3D-printed, low-carbon geopolymer concrete – a material formulated from industrial by-products such as fly ash and slag.
Artificial reefs mimic natural reef complexity and serve as critical habitats for marine life, from fish and crustaceans to coral polyps and algae. Algae, in particular, are key to marine ecosystems due to their roles in nutrient cycling, oxygen production, and carbon capture.
“Green concrete refers to concrete that utilises alternative binders and industrial by-products, significantly reducing the environmental footprint. At UFS, we are focusing on geopolymer concrete, which eliminates the high-energy processes associated with Portland cement, while offering greater chemical resistance - ideal for marine applications,” explains Dr Abdolhossein Naghizadeh from the Unit of Engineering Sciences.
3D printing nature’s complexity
One of the challenges in artificial reef development is replicating biologically inspired geometries that support diverse marine ecosystems. Traditional construction methods often fail in this regard, but additive manufacturing, or 3D concrete printing, is providing a solution.
The UFS Green Concrete Lab, in collaboration with the University of Johannesburg, is developing reef modules with intricate geometries and natural surface textures. These features support coral and algae attachment, accelerate ecological colonisation, and enhance habitat functionality. Biochar-based compost filters are also being integrated to aid algae-driven wastewater treatment.
A particularly novel avenue of research involves using 3D printing to recreate stromatolite structures. These serve as ancient blueprints for modern reef design, merging deep-time ecological understanding with advanced material science.
Biologically engineered hybrid stromatolites
In parallel to structural efforts, UFS is advancing biological approaches to stromatolite cultivation. From July 2025, researchers in the Unit of Engineering Sciences will initiate a large-scale experiment using microbial consortia in 60-litre tanks, scaling up to 1 m² hypersaline ponds. 3D-printed conical scaffolds, coated with materials such as PP-CaCO₃, hydroxyapatite, and silica gel, will accelerate microbial colonisation and lamination.
The goal: to achieve stromatolite growth of 14-16 mm in just 28 days - over 150 times faster than in nature. These hybrid systems are expected to produce 7-8 mg/L/day of oxygen, sequester carbon at 3.2 g/m²/day, and remove up to 90% of nitrates and phosphates from water. The potential applications extend from terrestrial ecosystem restoration to extraterrestrial life-support systems.
A multidisciplinary vision for sustainability
This work exemplifies the strength of interdisciplinary research at UFS, combining civil engineering, mechatronics, marine ecology, chemistry, microbiology, and digital fabrication. The Ecological Engineering Sciences stream fosters a vibrant environment for postgraduate students to develop practical, impactful solutions.
The Green Concrete Lab is central to these efforts, offering students and researchers access to advanced technologies and collaborative networks. Through their innovative work in 3D-printed green concrete and microbial systems, UFS researchers are addressing biodiversity loss, advancing sustainable construction, and contributing to the global climate agenda.
“Whether it's rethinking materials, restoring ecosystems, or redefining what concrete can be, our research is laying the foundation for a better, more sustainable world beneath the waves,” concludes Dr Maritz.