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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

During 2011: Sport
2011-12-01

Our sports stars set their gaols high and with hard work, dedication a good measure of determination they show that they will not give up until these goals are met. A place in the national team or a medal or award in hand is enough proof that our Kovsie sportsmen and women are serious about their successes on the sports field.

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Some of our stars this year were:

Athletics:

Thuso Mpuang, our Kovsie Sportsman of the year, represented South Africa during the World Athletic Championships in Deague, Korea. He obtained the silver medal in the 200m during the World Student Games in Shenzhen, China and a gold medal as a member of the 4 x 100m relay team.

Janette Siebert represented South Africa during the Southern Africa Championships in Maputo, Mozambique.

Boy Soke represented South Africa during the Africa Cross Country Championships in Cape Town. He also represented South Africa during the World Cross Country Championships in China.


Cricket:

The 21-year-old former Kovsie, Obus Pienaar, who was still playing cricket for our university club until the end of the season (end of March), has been playing abroad for the Irish cricket club Waringstown from the end of April 2011.
We are proud of Obus’ achievements, in particular his contribution to the match against the CIYMS. During this game, Obus hit the highest score ever in the Northern Cricket Unions when he scored 244 runs in only 114 balls. This included 22 sixes and 13 fours. During his innings in this match, Obus also broke the July 2004 record of his compatriot, AB de Villiers of the Proteas.


Hockey:

Lesley Ann George represented the Protea Women’s Hockey Team during the series against China, Belgium and Azerbaijan. She was also a member of the Protea Women’s Hockey Team during the Champs Challenge in Ireland. The team finished fifth.

Nicole de Vries represented the Protea Women’s Hockey Team during the series against China, Belgium and Azerbaijan. She was also a member of the Protea Women’s Hockey Team during the Africa Cup in Bulawayo. The team obtained a gold medal.

Hettie Oosthuizen represented the Protea Women’s Hockey Team during the series against China, Belgium and Azerbaijan.

Izelle Lategan represented the Protea Women’s Hockey Team during the series against China, Belgium and Azerbaijan.

Nicole Kemp was a member of the Protea Women’s Hockey Team during the Africa Cup in Bulawayo. The team obtained a gold medal.


Karate:

Elsabe le Roux was a member of the Protea JKA Shotokan Karate Team that participated in the Africa Zone 6 Championships in Maputo where she obtained a gold and silver medal.

Bruno Schwalbach was a member of the Protea JKA Shotokan Karate Team that participated in the Africa Zone 6 Championships in Maputo where he obtained two gold medals. He was also a member of the Protea JKA Shotokan Karate Team that participated in the Common Wealth Karate Championship in Australia where he obtained one silver and two bronze medals. He was a member of the Protea JKA Shotokan Karate Team that participated in the All Africa Games in Maputo Mozambique where he obtained a bronze medal.

Balungile Nchofe was a member of the Protea JKA Shotokan Karate Team that participated in the Africa Zone 6 Championship in Maputo, where he obtained a gold medal.


Netball:

Kovsies’ netball team has performed well over the past year with, amongst others, the inclusion of players in the SA Universities World-cup Group.

Karla Mostert and Maryka Holtzhausen participated during the World Cup in Singapore in the SPAR SA Protea team.

We are also proud of the eight players who have been included in the SA team. They are Zimari Smit, Sheri Duimpies, Ane Botha, Danique du Toit, Nieke Loubser, Karla Mostert, Fikile Mkhuzangwe and Lauren-lee Christians.

At the SA tournament, Ane Botha was named as the centre-court player of the tournament, whilst Karla Mostert was named as the best defending player. Karla has also been included in the SPAR SA Protea team to the All African Games, which start in Mozambique at the end of August.


Rugby:

Boom Prinsloo and Robert Ebershohn are representing the Springboks in the HSBC Sevens World Series.


Soccer:

Gabisile Hlumbane, our Kovsie Sportswomanof the year, is a member of the Banyana Banyana National Soccer Team. The team obtained a bronze medal at the African Women’s Championships during October 2010, a gold medal at the Unity Cup Hosted during December 2010, a silver medal at the COSAFA Women’s Championship hosted during July 2011 and qualified for the London Olympics in 2012.


Squash:

Paul Rodrigues represented the South African U/ 23 team at the All Africa Squash Championships in Johannesburg.


Triathlon:

Nelmaré Loubser represented the SA Elite Team during the World Championships in Spain.

 

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