Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
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

Consideration of the future of Reitz Residence
2008-03-17

Against the background of the recent events surrounding the video produced in Reitz Residence and in terms of a resolution passed by the Council of the University of the Free State (UFS) on 7 March 2008, the Rector and the Management of the UFS are at present considering the future of the Reitz Residence on the main campus of the University.

According to the Council resolution, this may include the possible closure of the residence and its conversion into either a new residence or accommodation facility or a different type of facility for use by the University. The guideline by Council is that it should become a beacon of transformation, hope and liberation.

The substantive issues that will be considered in taking the above-mentioned decision include, among others: the necessity of utilising the residence for other needs; the promotion of transformation and diversity in residences and on the campus; the educational and career interests of future residents; safety and security on the campus; and the effective functioning and strategic objectives of the UFS, including the place and profile of the UFS in the national and international university context, the UFS’s co-operation with other universities, organisations and experts, the UFS’s community engagement, and strategic partnerships with the business sector.

No such decision will be taken before the persons who will be affected directly by such a decision have been afforded a reasonable opportunity to make submissions and proposals for consideration by the Management. These direct stakeholders, in law, have been identified as:

  • students residing in Reitz at present;
  • parents of students residing in Reitz at present; and
  • present staff of Reitz.

In addition, any stakeholder or group of stakeholders are invited to make proposals by way of written submissions on the basis of the above-mentioned before or on 14 April 2008.

The University gives its assurance that whatever is ultimately decided, reasonable notice will be given to all the above-mentioned direct stakeholders and that the implementation will take place in a fair and reasonable manner to avoid causing unnecessary disruption for students, parents and staff.

Please send written submissions to:
The Vice-Rector: Student Affairs
Reitz issue
University of the Free State
PO Box 339
Bloemfontein 9300

Fax number: 051 444-0740
Email address: voorstelle@ufs.ac.za  

Prof. FCvN Fourie
Rector and Vice-Chancellor

Media Release
Issued by: Mr Anton Fisher
Director: Strategic Communication
Tel: 051 401 3422
Cell: 072 207 8334
E-mail: fishera.stg@ufs.ac.za  
17 March 2008

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept