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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

UV vestig hom afgelope eeu as leier op verskeie terreine
2004-05-11

Michelle O'Connor - Volksblad - 11 Mei 2004

Ondank terugslae nou 'n 'gesonde volwassene'

HOEWEL die Universiteit van die Vrystaat (UV) vanjaar sy eeufees vier en met 23 000 studente die grootste universiteit in die sentrale deel van die land is, was dié instelling se geboorte glad nie maklik nie. MICHELÉ O'CONNOR het met prof. Frederick Fourie, rektor, oor die nederige begin van dié instelling gesels.

DIE behoefte aan 'n eie universiteit in die Vrystaat het reeds in 1855, kort ná die stigting van Grey-kollege, kop uitgesteek.

Grey se manne het hulleself teen 1890 begin voorberei om die intermediêre B.A.-eksamens af te lê. Dié eksamen het hulle toegang gegee tot die tweede jaar van 'n B.A.-graad aan die destydse University of the Cape Good Hope, nou die Universiteit van Kaapstad.

"Presidente F.W. Reitz en M.T. Steyn het destyds albei die stigting van 'n universiteit hier bepleit. Die grootste rede was sodat die seuns van die Vrystaat nie weggestuur word nie.

"Dié twee se droom is op 28 Januarie 1904 bewaarheid toe ses studente hulle onder dr. Johannes Bril, as hoof/rektor van Grey-kollege, vir die graad B.A. ingeskryf het. Dié graad is aanvanklik deur die Kaapse universiteit toegeken.

"Net die klassieke tale soos Latyns en Grieks, die moderne tale, Nederlands, Duits en Engels, filosofie, geskiedenis, wiskunde, fisika, chemie, plant- en dierkunde is aanvanklik aangebied.

"Die UV se geboue het gegroei van 'n klein tweevertrek-geboutjie wat nou naby Huis Abraham Fischer staan, en verblyf in die Grey-kollege se seunskoshuis," sê Fourie.

Volgens hom is die universiteit se eerste raad en senaat tussen 1904 en 1920 saamgestel. Die eerste dosente is aangestel en die eerste geboue opgerig. "Dié tyd was egter baie moeilik.

"Die instelling het teen 1920 net 100 studente gehad en was geldelik in die knyp. Daar was geen vaste rektor nie en geen vooruitgang nie. Vrystaatse kinders is steeds na ander universiteite gestuur.

"Ds. J.D. Kestell, rektor van 1920 tot 1927, het egter dié instelling finaal gevestig.

"Hy het self studente van oor die hele Vrystaat gewerf en geld by onder meer kerke en banke ingesamel. Kestell het selfs Engelse ouers oortuig om hul kinders na die Greyuniversiteitskollege (GUK) te stuur en teen 1927 het dié instelling met 400 studente gespog.

"In die tydperk tussen 1927 en 1950 het die GUK weer verskeie terugslae beleef.

"In dié tyd was dit onder meer die Groot Depressie en die Tweede Wêreldoorlog. Die armblanke-vraagstuk het regstreeks op studente en dosente ingewerk en die politieke onderstrominge van dié tyd het die instelling ontwrig.

"Die GUK het egter oorleef en die Universiteitskollege van die Oranje-Vrystaat (UKOVS) is in 1935 gebore," sê Fourie.

Hy sê in dié tyd is verskeie fakulteite gevestig en teen 1950 het die UKOVS met 1 000 studente gespog.

Teen 1950 het dit 'n onafhanklike universiteit geword en die naam is verander na die Universiteit van die OranjeVrystaat (UOVS).

Dié tydperk is gekenmerk deur Afrikaner- en blanke selfvertroue en heerskappy. Studentegetalle het tot 7 000 in 1975 gegroei en heelwat vooruitgang het in dié tyd plaasgevind.

"Tussen 1976 en 1989 sukkel dieuniversiteit weer met onder meer ekonomiese krisisse, die land se politieke onstabiliteit en word die UOVS geï soleer.

"Een ligpunt in dié tyd is die toelating van die eerste swart studente, die nuwe Sasol-biblioteek en die fakulteit teologie wat die lig sien.

"Tussen 1990 en vanjaar het die UOVS verskeie op- en afdraandes beleef. Die universiteit doen nie net die eerste stappe van transformasie nie, maar begin ook aan 'n beleid van multikulturaliteit werk.

"Die UOVS se naam verander in 1996 na die Universiteit van die Vrystaat/University of the Free State en in 2001 word die Sotho-vertaling bygevoeg.

"Geldelike druk en probleme neem drasties toe en personeel word gerasionaliseer.

"Teen 2000 begin die UV met 'n draaistrategie en studentegetalle neem tot meer as 23 000 toe," sê Fourie.

Hy sê die UV het die afgelope eeu nie net verskeie terugslae oorleef nie, maar homself ook op verskeie gebiede as 'n leier gevestig.

Die universiteit behaal sy eie geldelike mikpunte, neem 'n nuwe taalbeleid van veeltaligheid aan en herbelê in personeel.

Die instelling inkorporeer die kampusse van die Vista- en Qwaqwa-universiteit en groei internasionaal.

Die UV vestig ook fondamente van 'n institusionele kultuur van verdraagsaamheid, geregtigheid en diversiteit.

"Die baba het in die afgelope eeu 'n gesonde volwassene geword."

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