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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

CR Swart Memorial Lecture: Mr Cecil le Fleur
2006-08-08

Khoe and San call for government to speed up policy dialogue with indigenous communities  

 Mr Cecil le Fleur, leader of the National Khoe-San Consultative Conference and member of the executive management of the National Khoe-San Council, has called for a national policy on indigenous peoples to protect the human rights and special needs of indigenous people in South Africa.

 Mr Le Fleur delivered the 38th CR Swart Memorial Lecture on the Khoe and San at the University of the Free State (UFS).  He commended the UFS for its serious approach to the Khoe and San and for initiating initiatives such as a research project on the Griqua in which various aspects linked to language, -culture, -history, - leadership, their role in the South African community (past and present) and the conservation of their historical cultural heritages will be covered.   

 “The policy dialogue with indigenous communities initiated by government in 1999 and supported by the International Labour Organisation (ILO), has been exceedingly slow, owing to political and bureaucratic problems,” said Mr Le Fleur.

 According to Mr Le Fleur the slow pace is also impacting negatively on the United Nations’ efforts to expand the international standards and mechanisms for human rights so as to include the special needs of indigenous peoples.

 “The successful adoption of a South African policy would probably have a major impact on the human rights culture of Africa and, more specifically, on the UN system,” he said.

 “South Africa has a powerful moral authority internationally and is willing to use this authority in multilateral forums. At this stage, however, South Africa’s Department of Foreign Affairs (DFA) may not take an official position on UN instruments and declarations pertaining to indigenous issues, until the Cabinet has resolved its own domestic policy position,” he said. 

 According to Mr le Fleur it therefore came as a great surprise when the DFA brought out a positive vote in the UN for the adoption of the "Draft Declaration on the Rights of indigenous Peoples" in June this year, even before the completion of the policy process. 

 Policy consolidation in South Africa is the primary key to creating a new policy climate in Africa in order to protect the rights of indigenous peoples.  “The existing constitution of the Republic of South Africa is one of the most liberal on the continent, and embraces the concept of redress of past discrimination.  It already includes a clause (Section 6) making provision for the protection of language rights for Khoe and San peoples - the fist peoples of southern Africa,” he said. 

 “If South Africa can effectively integrate this ‘third generation’ of collective rights within an existing democratic constitution, this will send a clear message to Africa and the world that indigenous rights are a necessary component of human and civil rights in modern democracies,” he said.

 Mr Le Fleur proposed an institutional framework based on set principles that would satisfy the needs and aspirations of the Griqua and other first indigenous peoples in South Africa.  “The proposed framework was based on the notion of vulnerability as a result of colonialism and apartheid, which stripped us of our indigenous identity, cultural identity and pride as people.  This injustice can hardly be addressed within the existing mechanisms provided by the current text of the Constitution,” he said.

 Mr Le Fleur also proposed that the principles of unique first-nation status, as recognised in international law, should be applied in the construction of the framework of the constitutional accommodation for the Khoe and San. 

 Mr Le Fleur further proposed that the Khoe and San’s indigenous status in constitutional terms must be separate from the constitutional acknowledgement of their status as a cultural community, as envisaged in sections 185 and 186 of the Constitution of 1996.

 According to Mr Le Fleur, the suggested mechanism should make provision for structures such as:

  •  A statutory representative council for First Indigenous Peoples of South Africa at a national level;
  • a separate Joint Standing Committee on Indigenous and Traditional Affairs, in both the National Assembly and the National Council of Provinces on which the Khoe and San can be represented;
  • a representative structure for the Khoe and San in the legislature of each relevant province; and
  • ex officio membership in the relevant structures of local government.

Media release
Issued by: Lacea Loader
Media Representative
Tel:   (051) 401-2584
Cell:  083 645 2454
E-mail:  loaderl.stg@mail.uovs.ac.za 
24 August 2006


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