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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

Letter to students from Prof Jonathan Jansen about student protest action at the UFS
2015-10-21

Dear Students

Student protest action at the University of the Free State

I wish to make clear that the senior leadership of the University of the Free State understands and supports the demands from students and their leaders that higher education be accessible to all students, especially the poor. For the past six years we have done everything in our power to meet that commitment to students who are academically talented, but simply cannot afford to pay; that is why our tuition fees remain among the lowest in the country. Our efforts to raise private funding have enabled thousands more students to study at the UFS than would have been possible on the government subsidy only. Whether it is the Staff Fund contributions (yes, our staff empty their pockets to support student fees) or the No Student Hungry (NSH) bursary programme (yes, we raise funds for food bursaries), we will continue our drive to fund students who cannot afford higher education. Let me repeat, no student with a solid academic record will be denied access to studies simply because they cannot pay.

Now, to the matter at hand. There is a national demand from students for a 0% fee increment for 2016. The Minister’s response, after consultation with stakeholders, was that universities should cap their 2016 fee increases at 6%. Despite this initiative from government, the protests continue on virtually all campuses across South Africa for the ‘no fee’ increase.

Our response, as the UFS leadership, is to continue engaging the SRC as the chosen leadership of our students in trying to negotiate a settlement on the matter. We have worked around the clock to be available to student leaders to find some resolution on 2016 fees. While we understand the demands of students, as university leaders, we can only work with the government subsidy we receive. Any agreement reached, cannot and must not place the university at academic and financial risk in its ability to deliver public higher education to the country - if that happens, everybody loses. Still, no matter what happens in terms of the response from government, the leadership door at the UFS remains open to finding a mutually acceptable solution to all parties in these deliberations.

Students, we are deeply concerned by the violence, intimidation and threats from the small group of protesting students. These dangerous and demeaning behaviours, like disrupting classes and verbally abusing students and staff, undermine the legitimate quest of students for relief concerning tuition fees. Such behaviour is completely unacceptable and the university will take action where required. We must also remember that we have an obligation to all 30 000 students whose right to learn without fear of violence and intimidation must be respected.

In conclusion, over the past few years we have worked hard to build a culture of mutual respect and embrace as we worked through some very difficult challenges on campus. You would have noticed that the university leadership responded quickly and sympathetically to reason and respect in difficult situations of rage and demonstration. A minority of students, with some outsiders, have come onto the campus to break down that culture in which, while we might disagree, we continue to work on the basis of mutual respect. I urge all students that, as we engage of this important problem of enabling greater access to higher education, we continue to remain true to the core values of our Human Project.

Best Regards

Prof Jonathan Jansen
Vice-Chancellor and Rector
University of the Free State


Letter to students from Prof Jonathan Jansen about student protest actions at the UFS (Pdf format)

 

 

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