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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

UFS Council unanimously approves two senior appointments
2014-11-24

The Council of the University of the Free State (UFS) unanimously approved the appointment of Dr Lis Lange as Vice-Rector: Academic and Prof Sechaba Mahlomaholo as Dean: Education during its meeting on Friday 21 November 2014.

Dr Lis Lange is currently Acting Vice-Rector: Academic at the University of the Free State, where she holds a substantive position as Senior Director heading the Directorate for Institutional Research and Academic Planning (DIRAP). Prof Mahlomaholo is Head of the School of Mathematics, Natural Sciences and Technology Education at the UFS.

“These are two exceptional and trusted academics with international stature and I am delighted to welcome them as part of the senior leadership of the UFS. Dr Lange’s skills set pertaining to academic management and quality assurance make her one of only a few people with similar skills in the country, while Prof Mahlomaholo is a leading expert in community-based education,” says Prof Jonathan Jansen, Vice-Chancellor and Rector of the UFS.

Dr Lange joined the UFS in 2011. Before this, she was the Executive Director (2006-2010) of the Higher Education Quality Committee of the Council of Higher Education (CHE), and Acting CEO of the same organisation between August 2007 and April 2008. She has been involved in the development and implementation of science and technology and higher education policy in South Africa for a decade and a half, working in different capacities in the Human Sciences Research Council, the National Research Foundation and the Council on Higher Education. Dr Lange has served as a member of the board of the International Network of Quality Assurance Agencies in Higher Education (INQAAHE) and has participated in several international initiatives on quality assurance. She is the editor of an academic journal focused on the humanities, Acta Academica.

She has undertaken research and published in the fields of history, higher education and quality assurance. Her major concern in both research and practice is the role of higher education in the development of democratic societies, based on social justice. Dr Lange studied in Argentina, Mexico and South Africa, where she obtained a PhD in South African history from the University of the Witwatersrand.

Prof Mahlomaholo is a graduate of the Universities of the North, Western Cape and Harvard University in the United States. He is a National Research Foundation (NRF)-rated Professor of Education.

Before joining the UFS, he worked at six other universities where he was Deputy Dean in the Faculty of Education (UNIN-QwaQwa), Head of Professional Education (Vista University), Professor and Director of Research and Postgraduate Studies (MEDUNSA), Professor and Director of Curriculum Development (Central University of Technology), and Research Professor (North-West University).

His research interests lie in designing strategies mounted on Bricolage, Participatory Action Research and Critical Emancipatory Research as theoretical bases. He leads the NRF-sponsored project on the creation of Sustainable Learning Environments in schools. In this Participatory Action Research project, 28 PhD and 22 MEd students participate under the guidance of 15 academics. The project has relationships with the Global Network project (St Petersburg University), the Post-Colonial Education project (West Indies University) and the Discourse, Power, Resistance project (Plymouth University and now University of London). He has served as guest editor in the following ISI-indexed, peer-reviewed and accredited journals: the South African Journal of Higher Education (2010 and 2014), the South African Journal of Education (2011), Communitas (2012), the Journal of New Generation Sciences (2012), the Journal for Transdisciplinary Research in Southern Africa (2013) and the Journal of Education Studies (2013).

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