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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 establishes links with the University of Ghent
2007-11-15

The University of the Free State (UFS) recently formalised its co-operation ties with the University of Ghent in Belgium. The two universities signed a memorandum of understanding during the Accenta Trade Fair, an annual event that incorporates activities such as business seminars, cultural events and exhibitions.

The signing of the memorandum of understanding took place via a live video conference linking the two institutions of higher learning.

“It was a wonderful moment because, after signing the memorandum of understanding on the Main Campus in Bloemfontein, the Rector and Vice-Chancellor, Prof. Frederick Fourie, actually showed us his signature on the screen while we were in Ghent”, said Prof. Koos Bekker of the Department of Public Management at the UFS, who was part of the delegation from the Free State.

The delegation consisted of the Premier, Ms Beatrice Marshoff, and several MECs and senior officials from the Free State provincial government, as well as the mayor, councillors and senior officials of the Mangaung Local Municipality. Several staff members of the UFS were also part of the delegation.

According to Prof. Bekker, the two universities will co-operate in various areas in terms of the memorandum of understanding.

“In the short term the collaboration will be focused on bio-fuels, public management and the digital divide, while discussions in other areas such as health services and organised crime are also under way,” he said.

As part of the memorandum of understanding, the following collaborative efforts are also envisaged:

Mr Lyndon du Plessis, a lecturer in the Department of Public Management, will be enrolled for a Ph.D. at both universities as from September 2008.

A research project involving both universities, the Mangaung Local Municipality and the City of Ghent, will be undertaken.
An investigation will be conducted by both universities regarding the possibility of writing a book on performance management in the public sector (negotiations with the publisher in this regard are under way).

An exchange programme involving students and staff from both universities will be established.

Academics from the UFS delivered papers during one of the forums that formed part of the Accenta Trade Fair programme in Ghent. Prof. Koos Bekker and Mr Lyndon du Plessis from the Department of Public Management delivered papers on strategic planning in practice on the first day of the event, which was devoted to scientific seminars. On the second day Prof. Lucius Botes, Director of the Centre for Development Support at the UFS, delivered a paper on economic development issues, and on the third day Prof. Gustav Visser, Associate Professor in the Department of Geography at the UFS, delivered a paper on tourism.

Papers on bridging the digital divide were presented during the video conference by academics in both Bloemfontein and Ghent.

As guests of honour at the Accenta Trade Fair, the Free State delegation was allocated the main exhibition floor space, covering 1 092 m². The Main Exhibition Hall covers a total surface area of 40 000 m². The Accenta Trade Fair attracts an average of 100 000 visitors annually. The UFS also participated as an exhibitor at the Trade Fair.

This visit was a follow-up of the previous visit, during which the Free State delegation was hosted by the City of Ghent and the provincial government of East Flanders for planning purposes from 14 to 24 April 2007.

Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt.stg@ufs.ac.za  
14 November 2007
 

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