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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

NRF researcher addresses racial debates in classrooms
2017-03-24

Description: Dr Marthinus Conradie Tags: Dr Marthinus Conradie

Dr Marthinus Conradie, senior lecturer in the
Department of English, is one of 31 newly-rated National
Research Foundation researchers at the University of
the Free State.
Photo: Rulanzen Martin

Exploring numerous norms and assumptions that impede the investigation of racism and racial inequalities in university classrooms, was central to the scope of the research conducted by Dr Marthinus Conradie, a newly Y-rated National Research Foundation (NRF) researcher.

Support from various colleagues
He is one of 31 newly-rated researchers at the University of the Free State (UFS) and joins the 150 plus researchers at the university who have been rated by the NRF. Dr Conradie specialises in sociolinguistics and cultural studies in the UFS Department of English. “Most of the publications that earned the NRF rating are aimed to contributing a critical race theoretic angle to longstanding debates about how questions surrounding race and racism are raised in classroom contexts,” he said.

Dr Conradie says he is grateful for the support from his colleagues in the Department of English, as well as other members of the Faculty of the Humanities. “Although the NRF rating is assigned to a single person, it is undoubtedly the result of support from a wide range of colleagues, including co-authors Dr Susan Brokensha, Prof Angelique van Niekerk, and Dr Mariza Brooks, as well as our Head of Department, Prof Helene Strauss,” he said.

Should debate be free of emotion?
His ongoing research has not been assigned a title yet, as he and his co-author does not assign titles prior to drafting the final manuscript. “Most, but not all, of the publications included in my application to the NRF draw from discourse analysis of a Foucauldian branch, including discursive psychology,” Dr Conradie says. His research aims to suggest directions and methods for exploring issues about race, racism, and racial equality relating to classroom debates. One thread of this body of work deals with the assumption that classroom debates must exclude emotions. Squandering opportunities to investigate the nature and sources of the emotions provoked by critical literature, might obstruct the discussion of personal histories and experiences of discrimination. “Equally, the demand that educators should control conversations to avoid discomfort might prevent in-depth treatment of broader, structural inequalities that go beyond individual prejudice,” Dr Conradie said. A second stream of research speaks to media representations and cultural capital in advertising discourse. A key example examines the way art from European and American origins are used to imbue commercial brands with connotations of excellence and exclusivity, while references to Africa serve to invoke colonial images of unspoiled landscapes.

A hope to inspire further research
Dr Conradie is hopeful that fellow academics will refine and/or alter the methods he employed, and that they will expand, reinterpret, and challenge his findings with increasing relevance to contemporary concerns, such as the drive towards decolonisation. “When I initially launched the research project (with significant aid from highly accomplished co-authors), the catalogue of existing scholarly works lacked investigations along the particular avenues I aimed to address.”

Dr Conradie said that his future research projects will be shaped by the scholarly and wider social influences he looks to as signposts and from which he hopes to gain guidelines about specific issues in the South African society to which he can make a fruitful contribution.

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