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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

Prof Loyiso Jita appointed as UFS Dean of Education
2017-11-22

 Description: Prof Melanie Walker, Research chair into Higher Education gets boost for five more years Tags: Prof Melanie Walker, Research chair into Higher Education gets boost for five more years

Prof Loyiso Jita, UFS Dean of Education
Photo: Johan Roux

The Council of the University of the Free State (UFS) has approved the appointment of Prof Loyiso Jita as Dean of Education during its quarterly meeting held on the Bloemfontein Campus on 17 November 2017.

“Prof Jita has a strong academic background and a good understanding of the higher-education sector. I look forward to working with him and to realise the vision of the university as a research-led, student-centred and regionally engaged university that contributes to development and social justice through the production of globally competitive graduates and knowledge,” says Prof Francis Petersen, UFS Rector and Vice-Chancellor.

“It is indeed a privilege for me to lead a team of committed teachers and researchers in the faculty, providing excellent service to our undergraduate and postgraduate students. I thank the Council and executive management for their trust in me,” says Prof Jita.

In January 2017, Prof Jita was appointed as the Acting Dean of the Faculty of Education at the UFS. He will assume the position of Dean of the Faculty of Education on 1 December 2017.

Prof Jita began his career as a Science and Mathematics teacher, after graduating from Wits University in 1988. He later took up a lectureship position at the University of Zululand, where he was awarded a Fulbright scholarship to read for a PhD at Michigan State University in the USA. In the mid-1990s, he worked as a policy researcher at the University of KwaZulu-Natal where he, among others, helped to compile the submission on the Violation of Educational Rights of South Africans during apartheid, to the Truth and Reconciliation Commission (TRC).

He joined the University of Pretoria (UP) in 2001, after returning from a post-doctoral fellowship at the Northwestern University in Chicago, and was later appointed Director of the Joint Centre for Science, Mathematics and Technology Education (JCSMTE). He left the UP in 2008 for an appointment as an associate professor at the University of South Africa (Unisa), where he later became the inaugural Director of the School of Education. In 2011, he became a full professor and was appointed as the acting Deputy Executive Dean in the College of Human Sciences at Unisa.

In 2012, he joined the UFS as Research Professor in the School of Mathematics, Natural Sciences, and Technology Education. In November 2014, he was appointed as the SANRAL Chair for Science and Mathematics Education. Professor Jita has published many articles on instructional leadership, teacher development and change, Science and Mathematics education, and has presented over 50 papers at local and international conferences. He has also supervised to completion more than 37 master’s and PhD graduates, and is currently the editor-in-chief for the accredited journal, Perspectives in Education (PIE).

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