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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

New Rector and Chancellor inaugurated at UFS
2003-02-07

NEW RECTOR AND CHANCELLOR INAUGURATED AT UFS

 Newly inaugurated Rector and Vice-Chancellor of the University of the Free State, Prof Frederick Fourie, has recommitted the university to the service of the broader community, through the pursuit of academic excellence and contributing to building a non-racial, democratic and just South Africa.

To make this a reality Prof Fourie proposed a social contract or accord between university constituencies and the community to chart the way forward to establishing a university that can meet the challenges of a developing democracy.

Prof Fourie was speaking at his inauguration ceremony on the Bloemfontein campus, where the former Ambassador to the United States, Dr Franklin Sonn, was also inaugurated as Chancellor of the UFS.

The twin inauguration ceremony – the first in the history of the UFS - was attended by former President Nelson Mandela, Education Minister, Kader Asmal, Free State Premier Winki Direko, and the executive mayor of Mangaung, Mr Pappie Mokoena, who all endorsed the appointments as evidence of the transformation of the UFS.

According to Prof Fourie, the greatest contribution that any university could make to social and economic development in South Africa was by being an excellent university that encouraged critical inquiry, scientific knowledge as well as community service.

“So whilst we cherish and foster the continuity of the university as part of the ageold international tradition of universities, this University embraces its particular role in this country now, embraces the changes in the form and scope of its role in this crucial period of our history. We are committed to making a real difference to the new nation,” he said.

His vision for the UFS was “to be a university of excellence, equity and innovation – a leader in research, teaching, community service, adult learning, transformation, non-racialism, non-sexism, multi-culturality and multilingualism – a contributor to our country and our continent’s growth and development – a truly South African university”.

Prof Fourie said the recent incorporation of the Qwaqwa campus of the University of the North into the University of the Free State, which is the first such incorporation to take place, would contribute to broadening access for poor communities to higher education. Introducing an innovation to the inauguration ceremony, Prof Fourie and the UFS staff pledged to their commitment to excellence and justice, quality and equity. Fourie is the 13th Rector of the University of the Free State, succeeding Prof. Stef Coetzee, and Dr Sonn is the 6th Chancellor, succeeding Ms Winkie Direko, Premier of the Free State.

In his inaugural address, Dr Sonn said the significance of today’s ceremony was that the UFS - as a former institution of the Afrikaner – had chosen to walk the path of justice and not merely survival. “This university has seemingly liberated itself. It is inclusively South African.

He said the academic community must play its role of vigilance and not indifference”. Referring to the stature of former president Mandela in international affairs, Dr Sonn said: “We must bring the weight ot science and critical analysis and interpretation to bear in support of Madiba and other moral giants.”
 

 

Inauguration Speech by Prof. Frederick C.v.N. Fourie  (PDF format)

Inauguration Speech by Dr Franklin A. Sonn (PDF format)

Statement by the Minister of Education, Professor Kader Asmal (PDF format)

Speech by Prof. Viljoen (PDF format)

Speech by Executive Mayor Mokoena - Mangaung Local Municipality (PDF format)

 

 

 

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