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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

Khayalami residence launches first in-house library
2016-04-21

Description: 2016 KL News Khayalami library  Tags: Khayalami residence launches first in-house library in the country
Bongani Mtotoba (left) and Sinoxolo Gcilitshana (right) at the first-ever 24 hour in-house library at Khayalami residence. The librarian and Deputy Residence Head respectively hope to revive the culture of reading on our Bloemfontein Campus.
Photo: Valentino Ndaba

“It is said that reading means to the brain what exercise means to the body. For that reason, we want to bring back the culture of reading to our students who are, after all, the future replacement of the leadership of our wounded and broken country,” said Sinoxolo Gcilitshana, Deputy Residence Head, and Prime of Khayalami.

Titles such as A Life Ever Lasting by Miranda Hearn, To Live Free by William Wilberforce, Powers of Darkness Powers of Light by John Cornwell, and Character Counts by Charles Dyer are among the 228 inspirational books on the shelves of Khayalami residence’s library. Tuesday 12 April 2016 was a proud moment for the residence as it launched the first library in the country located within a university residence on the Bloemfontein Campus of the University of the Free State.

Last year, Dimpho Jasa, a resident at Khayalami, approached Sinoxolo, who then held the Residence Committee (RC): Academics portfolio, with an idea of forming a book club. Sinoxolo had suggested that a library be established in order to make the book club sustainable. That conversation served as a foundation of the 24 hour in-house library.

“We started with five books last year,” said Sinoxolo, “and ever since we sent the message out, the Vice-Chancellor and Rector, Prof Jonathan Jansen has been supporting us together with the Vice-Rector, Prof Nicky Morgan, as well as the Dean of the Faculty of Education, Prof Sechaba Mahlomaholo, and the Head of the Department of English, Prof Helene Strauss.”  

Now, more than 170 young men have access to a growing library that is expected to hold 1500 books by September, when Sinoxolo steps down as the Prime. According to Bongani Mtotoba, the RC: Academics and librarian, some residents have made pledges to help expand the collection. “The response has been quite positive from the guys,” he said.

Borrowers are required to submit a book review upon returning the book. This feedback will be compiled by the English Department into a book available to the public.

Khayalami’s pioneering spirit has also seen the residence run a successful writing competition in 2015. It has since been introduced to the rest of the East College, and now will take place annually.  

For more information on how to donate books or enter the writing completion, contact Sinoxolo on 0783332203 or semsinoxolo@hotmail.com.

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