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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

Emma Sadleir talks about social media etiquette
2016-05-18

Description: Emma Sadlier Tags: Emma Sadlier

Emma Sadleir
Photo: Supplied

“We have all become celebrities, we have become social figures because of our power to publish information. We have all become brands, and we need to protect our brand. Digital content is sometimes dangerous content,” said Sadleir.

On 11 May 2016, the University of the Free State, in collaboration with the Postgraduate School, hosted, Emma Sadleir, a leading social media expert, in the Equitas Auditorium on the Bloemfontein Campus. She is an admitted advocate, specialising in social media law.  Dr Henriette van den Berg, Director of the Postgraduate School, described Sadleir’s presentation as a privilege for all the staff and students who attended.

Sadleir said that there are two important rules that staff and students of an institution should try to follow. The first is not to bring the name of the institution into disrepute; and the second is not to breach the goodwill of the institution or, in other words, not to bite the hand that feeds you.

“The common law, even if there is no policy, is that anything that brings the company into disrepute can lead to disciplinary consequences up to termination,” said Sadleir.

Sadleir focused on hate speech and free speech, stating that free speech is a right that is entrenched in the constitution, but, like every other right, it has limitations. She mentioned Penny Sparrow, Matt Theunissen, Velaphi Khumalo, and Judge Mabel Jansen, all of whom have been lambasted by the public over their racist posts on social media. Sadleir stressed that, even on social media, content has to be within the confines of the law, and people must remember our rights are not absolute. We have a lot of freedoms, but no one cannot disseminate hate speech.

“Would you publish whatever you thinking on a billboard, close to a busy highway with your name, picture and employers details or the institution you studying at? If you have no grounds to justify the comment, do not post it,” warned Sadlier.  

According to the South African Bill of Rights, everyone has the right to privacy, but an expectation of privacy has to be enforced. She said people over-document their lives on social media, decreasing your right to privacy drastically. “It is like CCTV footage of your life. It is simple, the more you take care of your privacy, the more you have,” said Sadleir.

Sadleir said it was important for Facebook users to have privacy settings where they can review posts where they are tagged. According to Sadleir, managing your reputation is not only limited to what you post about yourself but also managing what others post about you.

She cited a 2013 case in the Pretoria High Court in which a new wife wrote a scandalous Facebook post about her husband’s ex-wife, tagging the husband in the post. The courts found both the new wife and the husband guilty of defamation.

“If you have been tagged in something but have not been online and seen the content, you are then an innocent disseminator. The moment you are aware of the post you are liable for the content,” said Sadleir.

“It takes 20 years to build a reputation and five minutes to ruin it. If you think about that, you'll do things differently,” Sadleir said, concluding her presentation with the quotation from Warren Buffet.

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