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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

Open letter from Prof Jonathan Jansen to all UFS students
2014-02-22

Dear Students of the University of the Free State

In the past four years there has emerged a new consensus on the three campuses of the University of the Free State (UFS) about the things that divide us – such as racism, sexism and homophobia. Students and campus leaders have worked hard to develop this new consensus in residences and in the open spaces on campus. There can be no doubt that new bonds of friendship have developed across the markers of race, ethnicity, class, religion and sexual orientation. I bear witness to these new solidarities every day on the campus.

You chose a white student to head up the transformation portfolio on the SRC. You chose a black captain to head up the university’s first team in rugby. You chose a white “prime” as head of residence to lead a predominantly black men’s residence. You chose a South African woman of Indian descent as Rag Queen and last week, a black student from Cape Town as the men’s Rag winner—choices not possible and never made before in our campus history. Many of you have intimate friends who come from different social or cultural or religious backgrounds. You learn together, share rooms together, pray together and party together. In other words, in the day to day workings of this university campus, you have demonstrated to campus, city and country that we can overcome the lingering effects of racism and other maladies in this new generation. You have helped create a university community inclusive of people of diverse religions, abilities, class and sexual orientation.

I have said this repeatedly that from time to time this new consensus will be tested – when a minority of students, and they are a small and dwindling minority, still act as if these are the days of apartheid. And when that consensus is tested as it was this week, and as it will be tested in the future, only then we will be able to assess the strength and durability of our progress in creating a new South African campus culture of human togetherness based on respect, dignity and embrace.

The real test of our leadership, including student leadership, is how we respond when our transformation drive is threatened.

Let me say this: I have absolute faith in you, as students of this great university, to stand together in your condemnation of these vile acts of violence and to move together in your determination to maintain the momentum for the Human Project of the University of the Free State. We have come too far to allow a few criminals to derail what you have built together in recent years.

There will, no doubt, be unscrupulous people on all sides of the political spectrum wanting to milk this tragedy for their own narrow purposes. There will be false information, rumours and exaggerations by those who wish to inflame a bad situation to gain mileage for their agendas. That is inevitable in a country that is still so divided.

I ask you, through all of this, to keep perspective. Two or ten or even twenty students behaving badly do not represent 30,000 students; a minority of violent and hateful persons do not represent the ideals, ambitions and commitments of the majority. At the same time, let us be realistic – anyone who thinks you can drive transformation without resistance clearly does not understand the difficult process of change.

The events of the week remind us, however, that we still have a long road to walk in deepening social and academic transformation at our university. Yes, we have invested hundreds of hours in training and mentorship; we have created new structures – such as the Institute for Reconciliation and Social Justice – to capture the energy and imagination of students driving transformation; we have created many opportunities for students to study and travel on this and other continents to enable cross-cultural learning; we have established formal and informal opportunities to dialogue about difficult issues on and off campus between students and their leaders; and we crafted new curricula to enable teaching and learning on the big questions of our times.

But this is clearly not enough, and so I have decided on the following immediate next steps:
  1. We will meet for several hours next week to think about how we can deepen the transformation of our university after this terrible incident.

  2. We will arrange a University Assembly on the events of the past week so that we speak with one voice on human wrongs and to re-commit to human rights and we will continue with open forum discussions during the months to come.

  3. We will review the entire spectrum of programmes, from orientation to residence life to the undergraduate curriculum, to determine how effective our interventions really are in reaching all students with respect to basic issues of human rights.

  4. We will review our media and communications strategy to determine how far and deep our messages on human rights travel across all sectors of the university community. In this regard it is important that the campus be blanketed on a regular basis with our condemnation of human wrongs and our commitment to human rights.

  5. We will commission the Institute for Reconciliation and Social Justice to review the events of the past week and make recommendations on how we can improve the campus environment so that all students are protected from harm inside residences, classrooms and in open spaces of the campus.

  6. We will take the questions raised during this week into the academic community and to the general staff of the university so that all personnel also engage with our own roles and responsibilities with respect to campus transformations.

  7. We undertake to make annual report-backs on transformation to all stakeholders in public forums so that students and staff and external communities can track the progress of the university on matters of human rights on campus.

I wish to thank my staff for acting firmly as soon as this tragic event came to our attention. We worked through the night to find and identify the perpetrators. We traced the two students and immediately handed them to the police. They were expelled. And throughout this process we offered counselling and support to the victim of this violent act.

The two former students were expelled and will now face justice in the criminal courts. It is hoped that in the course of time they will come to their senses and seek restoration and reconciliation with the student they so callously harmed. They are not part of the university community anymore.

That is the kind of university we are.

Jonathan D Jansen
Vice-Chancellor and Rector
University of the Free State
20 February 2014

 
Note: The use of the word ‘campus’ refers to all three campuses of the UFS, namely the Bloemfontein Campus, South Campus and Qwaqwa Campus.

 

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