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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

“My time at the UFS was the golden gem of my career”
2016-07-04

Description: Zig Gibson Tags: Zig Gibson

Prof Alan St Clair Gibson
Photo: Oteng Mpete

“My time at the University of the Free State (UFS) was the golden gem of my career. I have worked at medical schools or biomedical research centres in the United Kingdom, United States and at some of the top medical schools in South Africa, but working at the UFS was one of the highlights of my career,” says Prof Alan St Clair Gibson, Head of the UFS School of Medicine.

After spending just over two years at the UFS, Prof St Clair Gibson resigned from the institution in June 2016 and will take up the position of Dean: Health and Human Performance Sciences at the Waikato University in New Zealand in mid-July, where he will assist to establish a new faculty for all the health-science disciplines. “It was a privilege to work at the UFS. I come from a strong research background and wanted to grow research at the university, which I achieved. I came to the UFS because of the Academic and Human Projects and am proud of what has been achieved at the School of Medicine during the time I was here,” he said.

Prof St Clair Gibson highlighted some of these achievements, including the development of a management infrastructure across the disciplines of the school. “The establishment of an executive management committee for the school, as well as research champions in departments, highlighted the importance of proper governance and strategic management. By developing data dashboards, my management team and I could develop an understanding of research income and productivity, how the school works, what the role of teaching and learning is, and how the school could benefit in terms of third-stream income from the many contracts obtained by its academic staff. As a result, contracts and the financial management model of the school have also been reconfigured to the benefit of the university so that the institution and school can benefit from it,” he said.

His strong belief in an open-door policy has made staff feel part of the environment and it has created an atmosphere of equality and inclusivity. He believes in staff development and has, for instance, established leadership and management courses for heads of departments. Another factor to be proud of is the increase in the number of young researchers who recently joined the school, such as Prof Ross Tucker, who is one of the foremost sport scientists in the country. “It is a fact that staff retire or resign in all schools and departments of any university. It is also true that these departures offer opportunities to bring new academic and professional staff into the UFS. In fact, for the first time virtually every department in the School of Medicine now has a full-time Head of Department and 46 new staff were appointed since January 2015,” said Prof St Clair Gibson.

“I am especially proud of contributing, together with the senior leadership of the UFS, to stabilise the relationship with the Free State Department of Health (DoH). With the assistance of these parties, as well as my executive management team, we could find a better way of working together to the benefit of the school and the province.’’

Transforming the student profile to be representative of the country’s demographics is another milestone Prof St Clair Gibson will remember. “The intake of black and white students is of such a nature that we now have a much more balanced ratio of black and white undergraduate students than before.”

“I wanted to stay longer to see the effect of all the changes I made at the school, but the deanship is an offer I cannot refuse. I would have liked to see a steadier increase in the number of permanent clinical staff and have worked hard with both the UFS management and the DoH to try and achieve that; but more work needs to be done.”

I have worked with a number of fantastic staff members at the school, who are determined to do good in a challenging environment. I am amazed at the energy of the university leadership and how the Human and Academic Projects are executed. My wish for the university is to maintain and grow its standards and for the School of Medicine to maintain its reputation as one of the best schools in the country. I will always be a proud alumnus of the UFS,” he said.

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