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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

nGAP lecturers welcomed by the UFS academic community
2016-06-30

Description: nGAP lecturers group photo Tags: nGAP lecturers group photo

University of the Free State’s newly-appointed nGAP
lecturers. From the left, Neo Mathinya,
Phumudzo Tharaga, and Kelebogile Boleu.

The University of the Free State (UFS) was allocated six positions as part of the Department of Higher Education and Training (DHET) New Generation of Academics Programme (nGAP). Four candidates have filled positions in the Faculty of Health Sciences, Faculty of the Humanities and the Faculty of Natural and Agricultural Sciences – with two positions still vacant.

According to Minister of Higher Education and Training, Dr Blade Nzimande, nGAP is part of the Staffing South Africa's Universities Framework, which focuses on the expansion of the size and compilation of academic staff at South African universities, especially with regard to transformation. The focus of the programme is the appointment of black and coloured candidates as well as women.

The Department of Soil, Crop, and Climate Sciences in the Faculty of Natural and Agricultural Sciences welcomed two nGAP lecturers, Phumudzo Tharaga and Neo Mathinya. The Faculty was allocated four positions. Two positions are filled, while two positions in the Department of Animal and Wildlife Sciences are almost ready to be filled with exceptional candidates.

Agrometeorologist with his feet on the ground
Phumudzo Tharaga holds an MSc from the UFS, and is currently pursuing a PhD. Tharaga’s research focuses on quantifying the water use efficiency of sweet cherry orchards under different climate conditions in the Eastern Free State. Tharaga will offer his students a wealth of practical experience, which he began accumulating while working at ABSA as an agro-meteorologist, before moving on to become a senior scientist at the South African Weather Service. In 2015, Tharaga became a research technologist at the Council for Scientific and Industrial Research (CSIR) and then returned to the UFS as an nGAP candidate at the beginning of 2016.  

Description: Beynon Abrahams, nGap lecturer  Tags: Beynon Abrahams, nGap lecturer

Beynon Abrahams, nGap lecturer
at the Faculty of Heath Sciences
Department of Basic medicine

Motivated scholar turned academic
Neo Mathinya, who hails from Taung in the North West, has made the UFS her home. She received both her undergraduate and honours degrees from the university. Apart from joining the department as a lecturer under the nGAP initiative, she is currently studying for her MSc in Soil Physics. She will continue with this research when she comes to her PhD. Mathinya’s research focuses on soil salinity - the process of increasing salt content - which affects the ability of plants to take up water, a process, known as osmotic stress. She will investigate the effects of irrigation water salinity on the grain yield and quality of malt barley.

Researcher with a passion for crime prevention
Kelebogile Boleu joined the Department of Criminology in the Faculty of Humanities, with a fresh take on diversion and crime prevention. Boleu holds a BA Criminology (Hons) and is now pursuing her Master’s degree. She worked for NICRO a non-profit organisation specialising in social crime prevention and offender reintegration, with programmes that prevent young and first-time offenders from re-offending, thus reducing crime. Boleu said that her practical experience makes her lectures to third-year criminology students exciting. Boleu’s research focuses on analysing the value of pre-sentencing reports in assisting adjudicators to make well-balanced judgments in cases.   

Research with a winning plan for fight against breast cancer
Beynon Abrahams joined the Department of Basic Medical Sciences in the Faculty of Health Sciences. Abrahams holds a BSc, BSc (Hons), and MSc in Medical Biosciences from the University of the Western Cape. Abrahams’ Master’s research focused on breast cancer, research on which he is building in his PhD. This doctoral research involves the exploration of P-glycoprotein, a protein expressed on cancer cell and responsible for multi-drug resistance in cancer treatment. The aim of this research is to develop a therapeutic drug treatment strategy that will improve breast cancer patient survival outcomes. Abrahams’s greater vision is to look at conventional cancer therapeutic regimens, to find ways in which they can be improved.

The nGAP initiative offers these young lecturers an opportunity for growth and development as academics, while providing them with opportunities they would have not have been exposed to otherwise.

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