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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

UFS Psychologist honoured for lifelong contribution
2015-12-09

Prof Dap Louw, distinguished professor and forensic psychologist from the University of the Free State, receives a Lifelong Achievers Award from the University of Johannesburg. From left is: Prof Theo Veldsman, head of the Department of Industrial Psychology and People Management at UJ, prof Louw, prof Deon de Bruin, Department of Industrial Psychology and People Management at UJ, and prof Daneel van Lill, dean at Faculty of Management at UJ.
Photo: Jan Potgieter, UJ

 

It is always good to be honoured by your own university, but it is even more special to be honoured by another university, according to Prof Dap Louw, distinguished professor and forensic psychologist from the University of the Free State (UFS), on an award he received from the University of Johannesburg (UJ).

On 5 November 2015, Prof Louw received the prestigious Lifelong Achievers Award from the Department of Industrial Psychology and People Management at UJ in recognition of the major contribution he has made during his career in psychology. He was one of two recipients of the award during this year’s UJ Top Achievers Awards Ceremony.

Prof Louw had great appreciation for his students and colleagues at the UFS, without who he would have been “without arms”.

Worthy legacy

The Lifelong Achievers Award is presented to retired academics that have, over their careers, consistently made significant contributions to their field, nationally and/or internationally, and have left behind a worthy legacy.

According to the description for the award, the recipient has left behind a legacy in his or her specific field which is gratefully acknowledged by all past, present and upcoming professional colleagues, students, clients and other stakeholders.

This description concludes with: “We are a better science and profession because of you”.

Career full of highlights

Prof Louw is the author or co-author of over 100 articles in accredited national and international journals, and he is an accredited NRF researcher.

He is the principal author and editor of several textbooks currently prescribed by 12 universities in South and Southern Africa. It is estimated that, over the years, more than 100 000 students have received their training via textbooks he has written with his wife, Prof Anet Louw.

Prof Louw holds a master’s and doctoral degree in Criminology, and a master’s and doctoral degree in Psychology. He is the only person in South Africa with these qualifications.
During his career as forensic psychologist, Prof Louw has testified in many familiar criminal cases in South Africa and Namibia.

The Academy of Science of South Africa presented him with the Stals Award for Psychology and he was honoured by The National Honor Society in Psychology in the USA as well.

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