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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

Weideman focuses on misconceptions with regard to survival of Afrikaans
2006-05-19

From the left are Prof Magda Fourie (Vice-Rector: Academic Planning), Prof Gerhardt de Klerk (Dean: Faculty of the Humanities), George Weideman and Prof Bernard  Odendaal (acting head of the UFS  Department of Afrikaans and Dutch, German and French). 
Photo (Stephen Collett):

Weideman focuses on misconceptions with regard to survival of Afrikaans

On the survival of a language a persistent and widespread misconception exists that a “language will survive as long as people speak the language”. This argument ignores the higher functions of a language and leaves no room for the personal and historic meaning of a language, said the writer George Weideman.

He delivered the D.F. Malherbe Memorial Lecture organised by the Department Afrikaans at the University of the Free State (UFS). Dr. Weideman is a retired lecturer and now full-time writer. In his lecture on the writer’s role and responsibility with regard to language, he also focused on the language debate at the University of Stellenbosch (US).

He said the “as-long-as-it-is spoken” misconception ignores the characteristics and growth of literature and other cultural phenomena. Constitutional protection is also not a guarantee. It will not stop a language of being reduced to a colloquial language in which the non-standard form will be elevated to the norm. A language only grows when it standard form is enriched by non-standard forms; not when its standard form withers. The growth or deterioration of a language is seen in the growth or decline in its use in higher functions. The less functions a language has, the smaller its chance to survive.

He said Afrikaans speaking people are credulous and have misplaced trust. It shows in their uncritical attitude with regard to the shifts in university policies, university management and teaching practices. Afrikaners have this credulity perhaps because they were spoilt by white supremacy, or because the political liberation process did not free them from a naïve and slavish trust in government.

If we accept that a university is a kind of barometer for the position of a language, then the institutionalised second placing of Afrikaans at most tertiary institutions is not a good sign for the language, he said.

An additional problem is the multiplying effect with, for instance, education students. If there is no need for Afrikaans in schools, there will also be no  need for Afrikaans at universities, and visa versa.

The tolerance factor of Afrikaans speaking people is for some reasons remarkably high with regard to other languages – and more specifically English. With many Afrikaans speaking people in the post-apartheid era it can be ascribed to their guilt about Afrikaans. With some coloured and mostly black Afrikaans speaking people it can be ascribed to the continued rejection of Afrikaans because of its negative connotation with apartheid – even when Afrikaans is the home language of a large segment of the previously oppressed population.

He said no one disputes the fact that universities play a changing role in a transformed society. The principle of “friendliness” towards other languages does not apply the other way round. It is general knowledge that Afrikaans is, besides isiZulu and isiXhosa, the language most spoken by South Africans.

It is typical of an imperialistic approach that the campaigners for a language will be accused of emotional involvement, of sentimentality, of longing for bygone days, of an unwillingness to focus on the future, he said.

He said whoever ignores the emotional aspect of a language, knows nothing about a language. To ignore the emotional connection with a language, leads to another misconception: That the world will be a better place without conflict if the so-called “small languages” disappear because “nationalism” and “language nationalism” often move closely together. This is one of the main reasons why Afrikaans speaking people are still very passive with regard to the Anglicising process: They are not “immune” to the broad influence that promotes English.

It is left to those who use Afrikaans to fight for the language. This must not take place in isolation. Writers and publishers must find more ways to promote Afrikaans.

Some universities took the road to Anglicision: the US and University of Pretoria need to be referred to, while there is still a future for Afrikaans at the Northwest University and the UFS with its parallel-medium policies. Continued debate is necessary.

It is unpreventable that the protest over what is happening to Afrikaans and the broad Afrikaans speaking community must take on a stronger form, he said.

 

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