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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

UFS SIFE is the best in SA!
2004-07-09

The SIFE team celebrates their victory with Jack Shewmaker, founder of SIFE in 1975 and past-president of Walmart in the USA, and Moses Kgosana, Chairman of KPMG SA.

The Students in Free Enterprise (SIFE) team of the University of the Free State competed in the National SIFE championships on Thursday, June 17, 2004 at Ceasar’s Convention Centre in Johannesburg.

Strong competition was experienced from the other ten participant SA universities, e.g. the Universities of the Western Cape, Kwazulu-Natal, Cape Town and RAU, but die UFS SIFE team retained the national championship for the third year running.

The team will now represent South Africa and the University of the Free State in Barcelona, Spain at die SIFE World Cup. The competition will be held from 22 to 24 September 2004.

The presentation team members for the competition were Tsholofelo Tlhomelang, Imameleng Matete, Kenneth Lefa, Kabelo Lephaka, Nadia van Staden, Tshepo Mahloko (Multi-Media), Werner Schmidt (Faculty Advisor). Supporting the presentation team were Lineo Peete, Keketso Ntene, Ruth Morienyane, Motaung Mathaba, Tshireletso Seekoe, Peter Letsoalo, Obakeng Msuthwana, Tshepiso Lebentle, JC Langeveldt and Michelle Stanley.

SIFE is a world-wide non-profit organisation with the express aim of encouraging students to spread their business knowledge - gained in the classroom - to the community, to promote and expand the principles of free enterprise.( www.sife.org )

The criteria by which SIFE-projects are measured are the following:

• How free markets work in the global economy.
• How entrepreneurs succeed by identifying a market need and then profitably producing and marketing a product or service to fill that need.
• The personal entrepreneurial, communications, technology and financial management skills needed to successfully compete.
• Practicing business in an ethical and socially responsible manner that supports the principles of a market economy.
• Measuring the results of projects, utilizing mass media and the Internet, involving non-business majors and utilizing a Business Advisory Board, communicating the program through a written report and verbal presentation.

The UFS’ SIFE-team’s presentation complied with all the above mentioned criteria. SIFE UFS’ education drive stretched from primary school learners, to adults who had been working for thirty years – this diverse group was taught about the free market system and its value in the global village. Business ethics and basic business principles were communicated in a fun and interactive way to learners. High-level business advice was given to entrepreneurs who started new projects, e.g. a brick-maker, and marketing advice were given to existing businesses in need of expansion.

If you are interested in helping SIFE UFS achieve its goals, e-mail Werner Schmidt at
schmidtw.ekw@mail.uovs.ac.za or phone him at 051 – 401 3376.

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