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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

Situation on the Bloemfontein Campus, and letter to parents
2016-02-28

Letter to parents from Prof Jonathan Jansen, Vice-Chancellor and Rector of the UFS 

 

Statement by Prof Jonathan Jansen, Vice-Chancellor and Rector of the University of the Free State (UFS) about the situation on the Bloemfontein Campus


1.    As all of you know, last night we witnessed a really tragic event at Xerox Shimla Park on the Bloemfontein Campus on the occasion of the Varsity Cup rugby match between NMMU (FNB Madibaz) and UFS (FNB Shimlas).
2.    The game started at 18:30 and about 17 minutes into the match, a group of protestors sitting on the north-eastern side of the stadium decided to invade the pitch and disrupt the game in progress.
3.    After a short while, some of the spectators also invaded the field, chasing and brutally beating those protestors whom they caught.
4.    As a university leadership we condemn in the strongest terms possible the vicious attack on the protestors. Nobody, repeat nobody, has the right to take the law into their own hands. While the protests were illegal and disruptive, it did not harm to the physical well-being of the spectators.
5.    The reaction from the group of spectators, however, not only opened old wounds, it trampled, literally and figuratively, on the dignity and humanity of other human beings. This we condemn in no uncertain terms, and no stone will be left unturned to find those who acted so violently on what should have been a beautiful occasion that also brought families and young children together to enjoy an evening of sport.
6.    I cannot over-emphasise our level of disgust and dismay at the behaviour of the spectators. It is NOT what the University of the Free State (UFS) is about and we are working around the clock to gather evidence on the basis of which we will pursue both charges and, in the case of students, also disciplinary action on campus.
7.    At the same time, the invasion of the pitch is also completely unacceptable and we will seek evidence on the basis of which we will act against those who decided to disrupt an official university event.
8.    Clashes between students occurred afterwards on campus and members of the Public Order Policing had to disperse some of them. The situation was stabilised in the early hours of the morning.
9.    Disruption continued this morning (23 February 2016) when students damaged some university buildings, a statue, and broke windows. Additional reinforcements from the South African Police Service were brought in to stabilise the campus. Additional security has also been deployed.


Broader picture
10.    We are very aware of the national crisis on university campuses and the instability currently underway. While the UFS has been largely peaceful, we have not been spared this turmoil, as last night’s events showed.
11.    We are also conscious of the fact that even as we speak, various political formations are vying for position inside the turmoil in this important election year. In fact, part of the difficulty of resolving competing demands is that they come from different political quarters, and change all the time.
12.    We are therefore learning from reliable sources that the Varsity Cup competition is, in fact, a target of national protests in front of a television audience.
13.    And we are aware of the fact that these protests are not only led by students but also by people from outside who have no association with the university. Just as the violent spectators involved on Monday night also included people from outside the university.

The demands

14.    My team has worked around the clock to try to meet the demands of contract workers demanding to be in-sourced. In fact, this weekend past, senior colleagues sat with worker leaders in the township to try to find ways of meeting their demands. We were hoping that such an agreement would be finalised by Monday afternoon (22 February 2016), but on the same Monday morning workers and students were arrested after moving onto Nelson Mandela Avenue, after which the South African Police Service (SAPS) took over as the matter became a public safety concern outside the hands of the university. Since then, it was difficult to return the workers to settle on a possible agreement.
15.    The fact is that the UFS has been in constant negotiation with contract workers to provide our colleagues with a decent wage and certain benefits. In fact, towards the end of last year we raised the minimum wage from R2 500 to R5 000. We were in fact hoping that the continued negotiations would improve that level of compensation even as we looked at a possible plan for insourcing in the future. We made it clear that if we could insource immediately, we would, but that the financial risk to the university was so great that it threatened the jobs of all our staff. Those negotiations were going well, until recently, when without notice the workers broke away and decided to protest on and around campus.
16.    While these negotiations were going on, the Student Representative Council (SRC) on Monday 22 February 2016 also decided to protest. While the vast majority of our 32 000 students were in classes and determined to get an education, a very small group led by the SRC President decided to protest; some invaded the UFS Sasol Library and the computer centre, and with the President eventually made their way to Xerox Shimla Park on which route they confronted the police, interrupted traffic and in fact injured some of our security staff as well as police officials.
17.    The university is definitely proceeding to collect evidence on these illegal and violent acts and will also act firmly against students involved in these protests.

Summary
18.    The events of Monday night represent a major setback for the transformation process at the UFS. While we have made major progress in recent years—from residence integration to a more inclusive language policy to a core curriculum to very successful ‘leadership for change’ interventions for student leaders—we still have a long way to go.
19.    One violent incident on a rugby field and we again see the long road ahead yet to be travelled. As I have often said before, you cannot deeply transform a century-old university and its community overnight. We acknowledge the progress but also the still long and difficult path ahead. We will not give up.
20.    We have 32 000 students on our campuses; the overwhelming majority of them are decent and committed to building bridges over old divides as we have seen over and over again. So many of our students, black and white, have become close and even intimate friends working hard to make this a better campus and ours a better community and country. Like all of us, they are gutted by what they saw on Monday, but the hundreds of messages I received from parents, students, and alumni this past 20 hours or so said one thing—keep on keeping on. And we will.

 

The Big Read: An assault on transformation (Times Live kolom deur Prof Jonathan Jansen: 25 Februarie 2016)

 

 

 


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