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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

During 2011: Infrastructure at the UFS
2011-12-01

Video clips:

Health Sciences Building
Clinical Skills Centre
Economic Sciences and Lecture Hall Building
Teacher Education Building
Biotechnology Building


A publication in which the infrastructure developments at the UFS are portrayed, was published this year. This publication celebrates the enormous development projects undertaken.
 
Description: 2011 Infrastructure_part 1 Tags: 2011 Infrastructure_part 1  Description: 2011 Infrastructure_part 2 Tags: 2011 Infrastructure_part 2  Description: 2011 Infrastructure_part 3 Tags: 2011 Infrastructure_part 3 
Constructive change (part 1) Constructive change (part 2) Constructive change (part 3)

Much has been done this past year to improve the infrastructure of our Bloemfontein and Qwaqwa Campuses with several buildings being built, some renovated and improvements made. Attention was specifically given to the growing need for lecture hall facilities and office space.

Some of the developments on our Bloemfontein Campus include: a brand-new entrance in Nelson Mandela Drive; a Memorial for Women and a Botanical Garden; a building for teacher education opposite the UFS Sasol Library; a building for our Faculty of Health Sciences opposite the Francois Retief Building; a Clinical Skills Centre for Allied Health Professions (the first in the country); and a building for our Faculty of Economic and Management Sciences between the Flippie Groenewoud Building and Wynand Mouton Theatre.

On our Qwaqwa Campus a building for teacher education is being constructed and some of the laboratories were refurbished and upgraded. More student accommodation is also well underway. A village development of four housing units that will accommodate 1000 students will be constructed on our Bloemfontein Campus.
Renovations and extensions were also made to some of the existing buildings such as the Architecture Building, the Biotechnology Building, the Department of Chemistry, the Stef Coetzee Building, the foyer of the Odeion, the Wynand Mouton Theatre and the Callie Human Centre. A staff restaurant has also been established on the Bloemfontein Campus and the building of ‘Little Professors’, a nursery school, is well underway.
“A building not only signals value to the outside; it also builds value on the inside. That is why it is important to notice how space has been organised and allocated to enhance the building of a community and to give academics, students and communities a sense of belonging to the university,” says Prof. Jonathan Jansen, our Vice-Chancellor and Rector.

The funding for most of the projects was made possible with an infrastructural grant from the Department of Education and Training.
 

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