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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

Professor launches his book, opposition parties attend
2011-03-22

Prof. Hussein Solomon
Photo: Stephen Collett

“We are good in opposing people, but we’re less good in opposing ideas.” This was how Prof. Jonathan Jansen, Vice-Chancellor and Rector of the University of the Free State (UFS) introduced the book launch of Against all Odds: Opposition Politics in Southern Africa.

The event was hosted in collaboration with the publisher under the title: Are opposition parties in South Africa in a crisis? This formed part of a series of dialogue sessions, organised by the Centre for Africa Studies, in the run up to the local elections.
 
Amongst those interested who attended the evening in the Senate Hall of the CR Swart Building on the Main Campus were various politicians, students, staff en a panel consisting of academics and the respective provincial representatives of the ANC and DA.
 
Dr Mcebisi Ndletyana from the Human Sciences Research Council (HSRC), acted as arbiter.
 
Proff. Hussein Solomon, author of Against all Odds: Opposition Politics in Southern Africa, also lecturer at the UFS, as well as Dirk Kotzé, Head of the Department of Political Science at Unisa, delivered enriching lectures on the stance and positioning of opposition parties.
 
Prof. Hussein, who spoke first, circumscribed the context of the political climate in the country, based on his book. “The problem that political science encounters is that everybody becomes experts on the internet, while they have no experience of what is happening in South Africa.” He said that when political parties in the country are under discussion, voters often allow myths and/or stereotyping to influence their concept of it. ‘’If there are no opposition parties, there is no democracy and people are deprived of their vote.”
 
Prof. Kotzé stated in his speech that it was not only opposition parties who had to make the government watch its step, but also the status that the country acquired, amongst others, from its connections, i.e. collaborative agreements such as BRICSA and the country’s inclusion in the G20. He left the audience with a question about how they were going to become involved in politics, and with his rhetoric question referred to options like social networks and movements.
 
Mr Sibongile Besani, the ANC'S secretary in the Free State, said the DA grew due to it’s swallowing of other parties; something he claims is taking the country backwards. He also described the use of personalities by opposition parties as means of association a weakness. He added that voters will continue voting for the ANC because they can associate themselves with the party’s vision.
 
In contrast, Mr Roy Jankielsohn, provincial leader of the DA, said voters and parties unite under their core vision for the country as like in the case of the ANC during the liberation struggles.
 
During the question-and-answer session, which followed after Mr Jankielson’s speech, Prof. Kwandiwe Kondlo, upon completion and summary of the discussions, stated firmly that the opposition parties are in a crisis. “The start of the solution is to recognise the problem. That is why our democracy finds itself in the state in which it is; because the opposition does not fulfil the role that they are supposed to fulfil.“ Prof. Kondlo is the head of the Centre of Africa Studies at the UFS.
 
He concluded by stating that the economic basis in the country was not transformed. “We cannot say that people determine their futures if they posses nothing. Opposition parties must start to communicate at this level in order to table something new. Our democracy must become more inclusive at political and material level.”

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