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Green Engineering: How UFS’s Green concrete can be an alternative to OPC cement

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

Address by the first Inaugural President of the Central SRC

2005-08-03

The UFS Central SRC

Address by the first Inaugural President of the Central SRC of the University of the Free State, Mr Tello Motloung on Wednesday 3 August 2003

The Chairperson of the UFS Council, Judge Faan Hancke,
The Vice-chancellor and Rector of the UFS, Prof Frederick Fourie
The Vice-Rector Student Affairs of the UFS, Dr Ezekiel Moraka
The Presidents of the main campus SRC and the Vista campus SRC
Colleagues in the Central SRC, campus SRCs, students and fellow South Africans

Please receive my heartfelt revolutionary greetings

Vice-chancellor and rector what I bring here with me assisted by facts, is just the work of my imagination. Like a love letter addressed to a sweetheart miles away, even though you do not know how she feels, what she wants to hear, and do not even know what she looks like.

I value speech as just an honest intimation, that’s why I got into a habit of establishing a dialogue with people, looking at each other’s face, and persuading one another of what we are saying.

Vice-chancellor, today marks an important milestone in the history of the existence of the UFS. Today reflects the confidence and trust that students of the UFS have placed in us. They are confident that the Central SRC has both the will and the capacity to take our university forward as we confront the challenge of transformation.

Students are confident that they are correct to trust the Central SRC as the principal agent of change in our university that is genuinely committed to the objective of building a non-racial, non-sexist and democratic university. We need to frankly ask ourselves, as CSRC members, whether are we up to all these challenges?

All Central SRC members have to understand this fully, internalize it, and ensure that everything we do, does not betray the confidence and trust of students, or disappoint their expectations. I say this knowing that all Central SRC members have committed themselves to serve the students of the UFS, black and white, and no one among us (CSRC) needs any special lectures about this central commitment.

The UFS should be an omnibus, welcoming everybody on board. But we should be a bus with a clear direction. We will certainly lose our way if we, as an institution, don’t have a clear road map spelling out where we are heading to.

There should be clear guidelines on the role of students in the transformation process. Students should also be viewed as role players in transformation along with the University management, and not just opposing forces. There is no right time, other than this one, to move away from the politics of opposition to politics of transformation.

However, we need the support of management to do so. The University should value the role and contribution of student leaders, hear our legitimate claims and consider them as part of political and policy decision making.

Vice-chancellor and Rector, it remains our task to ensure that the UFS is transformed into an institution that is seen to be playing a vigilant role in developing students academically, intellectually, socially, culturally, politically and otherwise. The process of transformation is not ending tonight, it is just beginning tonight.

Judge Hancke, Prof Fourie, Dr Moraka, fellow students and fellow South Africans, I lead students at this university with a sense of pride and duty, and I know very well that I lead men and women, students who are all determined that we reach our destination safely and on time.

A navy divided within its ranks will be destroyed and vanquished by the enemy, but the navy united in purpose and action, loyalty and commitment will not sink but sail on to victory.

It is befitting to mention that every drop of my blood is telling me that the UFS is my home. I firstly became a student here, I became the SRC treasurer in my first year here, I became the deputy president here, and I became the first president of the Central SRC of the UFS.

Therefore you should never doubt my commitment towards the transformation of this university. To paraphrase what was said by students at another institution, “If there is no UFS in heaven, then I am not going.”

Let me conclude by thanking my ancestors for teaching me that even if I wined and dined with kings and queens, I am not a king myself, so I should not turn my back on people who made me what I am today.

Most importantly, I would like to thank the Almighty God and the grace of our Lord Jesus Christ for giving me time and power to lead this university.

It will be theoretically irresponsible if I ended my speech without indicating that “Only a Kovsie knows the feeling”.

I thank you.

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