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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

An exceptional year at Kovsies — one of the most successful years in academic achievement
2014-12-04

 

The University of the Free State (UFS) had an exceptional year, with many staff members and students performing both nationally and internationally. Considerable progress has also been made in improving the academic standards of the university.

“So far, this has been one of the most successful years in academic achievement. The UFS now has the highest academic pass rate in years, partly as a result of the admission standards which were raised four years ago.

“We now also have the highest rate of research publications, one of the highest publication figures for scholarly books in history, three Mandela Rhodes scholars and several international communication awards”, says Prof Jonathan Jansen, Vice-Chancellor and Rector of the UFS.

“The university now attracts top professors from all over the country and other parts of the world and for the first time in many years, two researchers received A-ratings from the National Research Foundation (NRF). This is the first time in the history of the UFS that two A-ratings were awarded simultaneously. The most researchers ever were rated by the NRF this year. After the constant turmoil of a few years ago, Kovsies has now become one of the most stable campuses in South Africa,” Prof Jansen says.

The impartial findings of a recent survey of UFS stakeholders showed that our values are endorsed by 92%; 86% agrees with our vision; 81% agree with our goals; 77% agree with our transformation; 78% believe that we are inclusive; and 78% applauded our overall reputation index. “These figures are very different from a few years ago when the university experienced a crisis,” he says.
 
According to Prof Jansen, the UFS’s financial situation is one of the most stable of all universities in South Africa, with a strong balance sheet and growing financial reserves – way better than before. This is exactly the reason why the UFS received confirmation from the Independent Regulatory Board of Auditors (IRBA) this year that we complied with international standards of reporting for the financial year which ended on 31 December 2013.

“I am also pleased to report that the crisis in the delivery of health services in the Free State province has been resolved due to collaboration between the UFS Management (including the Dean: Health Sciences and Head of the School of Medicine), the Department of Health and the Premier, Mr Ace Magashule. Although the loss of skilled personnel is still a concern, the Dean and Head of the School of Medicine are recreating the Health Services Platform at Universitas Hospital. However, the academic training of no undergraduate medical student or any student in the Health Sciences was influenced by the crisis in the Universitas and Pelonomi Hospitals”, he says.

The UFS is regarded around the world as a model of transformation and reconciliation in the student body. The recent SRC elections are only the most visible example of how far we have come in terms of leadership diversity. “Not a week goes by in which other universities, nationally and abroad, do not come to Kovsies to consult with us on how they can learn from us and deepen their own transformations, especially among students”, Prof Jansen says.

“The UFS will continue its model of inclusive transformation which provides opportunities for study and for employment for all South Africans, including international students and colleagues. We remain committed to our parallel-medium instruction in which Afrikaans remains a language of instruction; we are in fact the only medical school in the country that offers education and training in Afrikaans and not only English. We provide bursaries and overseas study opportunities to all our students, irrespective of race. And our ‘future professors’ programme is richly diverse as we seek the academic stars of the future. But we remain steadfast in our goal of making the UFS a top world university in its academic ambitions and its human commitments,” Prof Jansen says.

 

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