Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
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

International speakers discuss diversity
2014-02-11

 
Dr Charles Alexander from UCLA
Photo: O'Ryan Heideman

International and local experts recently gathered on the Bloemfontein Campus to deliberate over the topic of diversity.

Student participation and mobility dramatically increased in higher education worldwide. Cultural, political, economic and social factors on a national and global scale, have brought the reality of diversity into the operational spaces of Higher Education Institutions. These challenges are not exclusive to South Africa, though. In the Netherlands and USA, universities are also challenged by the demands of an increasingly diverse student population.

Prof Jonathan Jansen, Vice-Chancellor and Rector of the UFS, acted as one of the keynote speakers during a two-day colloquium hosted by the Institute for Reconciliation and Social Justice. In an impelling address, Prof Jansen argued that change cannot be affected on a university campus if the surrounding community does not change as well. He also noted the spread of a culture of silence surrounding issues of misbehaviour. He urged that we need to find courage again to speak out. From the level of government, media and churches to the private spaces of our homes, we have to co-create an environment of care.

This message closely tied in with that of Prof Shirley Tate’s from the University of Leeds. In her keynote, she asserted that mere tolerance of someone different from you can lead to even more alienation. The path to true reconciliation is grounded in the intimacy of friendship. Friendship and empathy lead to trust and transcend racism.

Another keynote speaker from abroad, Dr Charles Alexander from the University of California, delineated a model for inclusive excellence. He explained that the major problem of true transformation is not due to a lack of ideas, but in the implementation thereof. “Realities of implementation short circuit the change process,” he said. He explained how campus environments can adapt in order to support and enhance lasting inclusivity.

We have to become complicit in the process of transformation, Prof Dr Ghorashi, Professor of Diversity and Integration at the Vrije Universiteit Amsterdam, conveyed. Linking up with the issue of silence, she demonstrated the power of speaking out, using examples from her extensive research among victims of violence. It is imperative, she maintains, that for transformation to materialise, we need to create safe spaces in which we can share our vulnerabilities.

Footnote: Due to unfortunate circumstances, both Prof Dr Ghorashi and Prof Shirley Tate could not personally attend the colloquium as planned. Their respective keynotes were read to the audience on their behalf.

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept