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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

Multilingualism and exclusion to be discussed
2007-11-27

 
 Some of the UFS staff who will be attending the colloquium on multilinguisim and exclusion in Antwerp, Belgium are, from the left, front: Prof. Theo du Plessis and Ms Susan Lombaard; back: Prof. Johan Lubbe and Mr Roelof Geyser. All are from the Unit for Language Management.
 
Multilingualism and exclusion to be discussed

Five members of the University of the Free State’s (UFS) Unit for Language Management will be taking part in an international colloquium at the University of Antwerp in Belgium on the theme: “Multilingualism and exclusion – perspectives on language and society” this week.

“During this week’s colloquium, approximately twenty South African and Flemish colleagues will reflect on the complex relationships within multilingual communities, where a variety of factors can contribute to the inclusion or exclusion of individuals or communities. Some of the papers will focus on policy measures (“from above”) with regard to the relative position of languages in a particular state, and the impact of these policy measures on the lives of language users. Others will investigate perceptions and “appropriation” (“from below”) by the same language user. In view of the multiple points of departure, the colloquium should contribute towards a better understanding of the dynamics within multilingual communities,” said Prof. Theo du Plessis, Director of the Unit for Language Management at the UFS.

“To give expression to the theme of multilingualism and exclusion, lectures will be presented in three languages, namely Afrikaans, English and Dutch. Several postgraduate students (from South Africa and Flanders) will also have an opportunity to report on investigations they are conducting within the framework of their master’s degree and doctoral studies,” said Prof. Du Plessis.

The colloquium is a follow-up of an international symposium held at the UFS during April 2006 in which a considerable number of outstanding scholars from various countries participated.

According to Prof. Du Plessis, the proceedings of the symposium held last year will be released in book form as part of the unit’s publication series “Studies in Language Policy in South Africa”, published by Van Schaik Publishers.

This sixth issue in the series entitled: “Multilingualism and Exclusion. Policy, Practice, Prospects” will be released tonight (26 November 2007) by the Permanent Deputy of the Province of Antwerp at a prestigious event during the colloquium. The issue was edited by Prof. Du Plessis, Prof. Pol Cuvelier (University of Antwerp), Dr Michael Meeuwis (University of Ghent) and Ms Lut Teck (Institute for Higher Education and the Arts in Brussels).

The UFS will be represented by Prof. Du Plessis, Prof. Johan Lubbe, Ms Susan Lombaard and Mr Roelof Geyser of the Unit for Language Management, as well as Prof. Jackie Naudé of the Department of Afro-Asiatic Studies, Sign Language and Language Practice. Representatives from the universities of Pretoria, Johannesburg, North West and the Monash University in Johannesburg will also be participating in the colloquium.

Media Release
Issued by: Lacea Loader
Assistant Director: Media Liaison
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl.stg@ufs.ac.za
26 November 2007

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