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29 November 2022 | Story Leonie Bolleurs | Photo Leonie Bolleurs
UFS green concrete
The Department of Engineering Sciences (EnSci) welcomes collaborations with other departments at the UFS. Pictured here are, from the left: Louis Lagrange, Head of EnSci, Prof Kahilu Kajimo-Shakantu, Head of the Department of Quantity Surveying and Construction Management, Dr Abdolhossein Naghizadeh, and Megan Welman-Purchase, analytical scientist in the Department of Geology.

More than 30 million tonnes of fly ash (residue from coal combustion in power plants) are generated in South Africa annually, with 96% of that being disposed of in landfills. There is thus more than enough of this key ingredient to produce green concrete. 

Green concrete, so called due to its environmentally friendly benefits, is an eco-friendly alternative to conventional concrete based on the Portland cement binder. During the production of green concrete, less carbon dioxide is released into the atmosphere than with the production of ordinary Portland cement (OPC). The latter accounts for up to 8% of all global carbon emissions.

Successful tests

In the Green Concrete Lab, established in 2021 within the Department of Engineering Sciences (EnSci) on the Bloemfontein Campus of the University of the Free State (UFS), Dr Abdolhossein Naghizadeh, Senior Lecturer, researcher, and engineer, is working on green cement and concrete projects.

He uses ‘geopolymer’ technology and a mix of waste materials, alkaline solutions, and recycled aggregates to form concrete mixtures that can provide properties similar to conventional concrete.

Besides being a synthesised inorganic material (not a petrochemical product), the geopolymer cement he introduced has the following properties: it is made from a reaction between aluminosilicate materials and strong alkalis (5-7% of the concrete mixture), it uses water and by-products as raw materials, it does not calcinate lime, thus giving it a low carbon emission, and it is also beneficial from a waste management point of view. 

The waste materials used can include waste from industrial and agricultural sources, such as fly ash, rice husk ash, sugar-cane bagasse, or corncob ash, as well as natural materials such as volcanic ash. In South Africa, sufficient amounts of industrial and agricultural waste are available. 

“So far, we have successfully tested various types of green concrete based on different waste materials,” says Dr Naghizadeh. 

Besides researching the green mixture proportions in the lab, Dr Naghizadeh and his students focused their attention on establishing the strength, durability, workability, and production cost of the product. 

They compared green concrete with conventional concrete. Green concrete’s workability is slightly lower (but he believes that with appropriate mix design it can be corrected), and it has a much higher compressive strength (50-90 MPa), a smaller carbon footprint, and comparable production costs to conventional concrete (depending on the mix design). A very high level of resistance against alkali-silica reaction (concrete cancer) is also present, as well as resistance to carbonation, sulphate attack, and acid attack.
So far, we have successfully tested various types of green concrete based on different waste materials.– Dr Naghizadeh. 

He explains, “The superior durability performance of green concrete is related to its chemical compositions and microstructure. For example, the lack of calcium content in the composition provides better resistance to alkali-silica reaction. At the same time, stronger bonds between elements and polymeric microstructure provide better resistance against acids and fire.”

With all the work and research of the past year and a half, Dr Naghizadeh says they are at the stage where they can prescribe green concrete production recipes for the industry parties based on the specified application and the materials they have.

Biggest accomplishments

“We transferred most of the experimental works to the Green Concrete Lab at the beginning of 2022, which improved our productivity tremendously. Since then, nine journal papers and three peer-reviewed conference papers have been published as outputs of the research projects. Currently, there are also multiple publications under review or in the development stages,” says Dr Naghizadeh.

In addition to him, there are three master's students and one research associate working on their own individual projects.

The department is very proud of its research outputs. Dr Naghizadeh was either author or co-author of all 12 research papers. The focus of these papers was mostly on the formulation of green concrete, based on locally available agricultural waste materials, the formulation of one-part geopolymer cement (when aluminosilicate raw material is replaced with pre-activated aluminosilicate material, water can be used instead of alkali solution), and the development of ambient-cured green concrete (replacing the aluminosilicate raw material with a blend of materials).

Dr Naghizadeh is also the project leader of a group of scientists from local and international universities who are researching sustainable construction materials. These institutions include the Universities of Johannesburg, KwaZulu-Natal, Yaoundé in Cameroon, Erzurum Technical University in Turkey, as well as Nelson Mandela University and the Central University of Technology, which recently came on board. 

 


 


News Archive

Open Day engulfs Bloemfontein Campus with colour, crowds and cheer
2013-05-04

 

08 May 2013
Photo: Lelanie de Wet


   Open Day YouTube video

The procession – comprising of Prof Jonathan Jansen and the Deans of all the UFS faculties – stately entered a packed Callie Human Centre on Saturday morning 4 May 2013. As everyone took their seats, all the lights were abruptly cut, leaving the hall in a stunned silence. Suddenly brilliant beams of green, blue and red lights cut through the dark, exploding into a spectacular laser show.

Open Day 2013 on the Bloemfontein Campus was officially under way.

The audience of parents and prospective students were awe-struck by a transfixing electric guitar performance, dancers lit up by LED suits, pulsing music and finally Corneil Muller singing to the accompaniment of Prof Jansen behind the piano.

Vice-Chancellor and Rector, Prof Jansen immediately made attendees from across all nine provinces, Namibia, Lesotho and several other countries feel at home and embraced by the university. During his welcoming address, Prof Jansen referred to the fact that Kovsies places the bar high when it comes to achievement. “We expect more of our students,” he said. “Passing is not important, passing wéll is important.” He stressed that at the university we teach students to be decent, to be exceptional people. “We place a high premium on being an outstanding human being.” He went on to say that our students are better than the previous generation – they do not carry the baggage of the old.

Prof Jansen also communicated the university’s commitment to developing leaders with an understanding of the world. This is why the university afford students the opportunity, amongst other things, to study abroad. Students have access to a wide variety of organisations and the privilege to have access to leaders who they can converse with. Kovsies strives to produce leaders, not only in the community, but on a global platform.

To demonstrate this last point, top Kovsie achievers joined Prof Jansen on stage to relay their stories of perseverance, courage and success. Included among these stars, were athlete Danél Prinsloo; Varsity Cup Player that Rocks 2013 Oupa Mohoje; DW Bester, a Rhodes Scholar currently studying at Oxford University in the United Kingdom; and Jurie Swart, who ranked under the top five in the 2012 International Graduate Architecture Student Design competition.

The residences pulled out all stops when it came to the presentation of their individual stalls. The gardens in front of the Main Building burst with colour, sound, dancing and laughter as the residences competed to draw the most visitors. The faculties also opened their doors for a glimpse at the exciting opportunities awaiting prospective students.

A record amount of visitors went home with the words of Rudi Buys, Dean of Student Affairs, inscribed in their minds summing up what the UFS is all about: “Where a sense of community matters more than the colour of your skin.”

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