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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

The solution to student food insecurity is a holistic approach
2017-02-10

Description: Dietetics read more Tags: Dietetics read more

Dr Louise van den Berg from the Department of
Nutrition and Dietetics says the University of the Free State
is taking steps to teach students how to budget and make
them aware how important food nutrition is.
Photo: Pixabay 

Research at the University of the Free State (UFS) has indicated that nearly 60% of students are victims of food insecurity and suffer from hunger most of the time. The research by the UFS Faculty of Health Sciences shows that a further 25% are food insecure but are not hungry most of the time.

Senior Lecturer in the Department of Nutrition and Dietetics, Dr Louise van den Berg, says food insecurity is common among student populations across the world. However, local research shows that it is almost double that of tertiary institutions in developed countries.

Food insecurity among students caught many people off-guard
Dr Van den Berg says in South Africa nobody had really looked at the problem until recently “It seems student food insecurity has caught many people off-guard.” She says people tend to think of tertiary students as a privileged group.

The research has now indicated how deep the problem really is on campus. The students that most likely go hungry are single, male, black or coloured, and are generally first-generation students.

They are also mostly undergraduates, those paying their studies from non-bank loans or bursary means, those not living with their parents or guardians or those that need to support somebody else financially.

The results further indicate that those that are likely to suffer from hunger seldom or never have enough money for food but have to borrow money for food, have to ask for food, sell items to get food or steal food.

“A healthy student is a
successful student.”

Bursary money send back home for parents to survive
Dr Van den Berg agrees that one of the main reasons for the situation is economic stress. Research has shown students rarely spend money on food when resources are scarce. Furthermore, parents of students studying with bursaries are not always able to fully support them on campus. Some students send bursary money back home for their parents to survive.

She says other factors that contribute to campus food insecurity are that all over the world universities have terminated catered food halls due to high costs. “To a large extent this has created a food desert for students and now they need to look after themselves.”

To throw money at the problem does not seem to be the answer. 

Students are food-uncertain beings
The research indicates that young people on campus do not know where to buy food, much less the correct, nutritional food they need. Dr Van den Berg says most universities are now aware of the problem and have been taking steps. This includes teaching students how to budget and making them aware how important nutrition is for their success and their responsibility for themselves.

Universities are also looking at private funding for food aid and food schemes. Dr Van den Berg says other solutions are the restructuring of bursary fees, student self-help initiatives and food gardens.

The Faculty of Health Sciences is taking the initiative to manage a food blog on the UFS website. It will also use other social media platforms to post food-preparation videos and recipes for students.

Dr Van den Berg says it is important to grow the 15.6% group of students who indicated they are food secure because a healthy student is a successful student.

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