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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

#Women'sMonth: Save the children
2017-08-10

Description: Trudi O'Neill Tags: : rotaviruses, young children, Dr Trudi O’Neill, Department of Microbial, Biochemical and Food Biotechnology, vaccine 

Dr Trudi O’Neill, Senior lecturer in the Department of
Microbial, Biochemical and Food Biotechnology.
Photo: Anja Aucamp

Dr Trudi O’Neill, Senior lecturer in the Department of Microbial, Biochemical and Food Biotechnology, is conducting research on rotavirus vaccines.

Dr O’Neill was inspired to conduct research on this issue through her fascination with the virus. “The biology of rotaviruses, especially the genome structure and the virus’ interaction with the host, is fascinating.”

“In fact, it is estimated that, globally, ALL children will be infected with rotavirus before the age of five, irrespective of their socio-economic standing. However, infants and young children in poor countries are more vulnerable due to inadequate healthcare. The WHO estimates that approximately 215 000 deaths occur each year. This roughly equates to eight Airbus A380 planes, the largest commercial carrier with a capacity of approximately 500 seats, filled with only children under the age of five, crashing each week of every year.”

Alternative to expensive medicines 
“Currently, there are two vaccines that have been licensed for global use. However, these vaccines are expensive and poor countries, where the need is the greatest, are struggling to introduce them sustainably. It is therefore appealing to study rotaviruses, as it is scientifically challenging, but could at the same time have an impact on child health,” Dr O’Neill said.

The main focus of Dr O’Neill’s research is to develop a more affordable vaccine that can promote child vaccination in countries/areas that cannot afford the current vaccines.

All about a different approach 

When asked about the most profound finding of her research, Dr O’Neill responded: “It is not so much a finding, but rather the approach. My rotavirus research group is making use of yeast as vehicle to produce a sub-unit vaccine. These microbes are attractive, as they are relatively easy to manipulate and cheap to cultivate. Downstream production costs can therefore be reduced. The system we use was developed by my colleagues, Profs Koos Albertyn and Martie Smit, and allows for the potential use of any yeast. This enables us to screen a vast number of yeasts in order to identify the best yeast producer.”

Vaccination recently acquired a bad name in the media for its adverse side effects. As researcher, Dr O’Neill has this to say: “Vaccines save lives. By vaccinating your child, you don’t just protect your own child from a potentially deadly infection, but also other children in your community that might be too young to be vaccinated or have pre-existing health problems that prevents vaccination.” 

A future without rotavirus vaccination?

Dr O’Neill believes a future without rotavirus vaccination will be a major step backwards, as the impact of rotavirus vaccines has been profound. “Studies in Mexico and Malawi actually show a reduction in deaths. A colleague in Mozambique has commented on the empty hospital beds that amazed both clinicians and scientists only one year after the introduction of the vaccine in that country. Although many parents, mostly in developed countries, don’t have to fear dehydrating diarrhoea and potential hospitalisation of their babies due to rotavirus infection anymore, such an infection could still be a death sentence in countries that have not been able to introduce the vaccine in their national vaccination programmes,” she said. 

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