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23 June 2021 | Story Leonie Bolleurs | Photo Supplied
The Department of Engineering Sciences (EnSci) – under the leadership of Dr Abdolhossein Naghizadeh – is heading a collaboration of scientists to create a green concrete that will reduce the impact of cement on the environment.

Conventional cement production is responsible for more than 6% of the overall carbon emissions in the world, which ultimately affects global warming.

The Department of Engineering Sciences (EnSci) at the University of the Free State (UFS) – under the leadership of Dr Abdolhossein Naghizadeh – is heading a collaboration of scientists from universities in South Africa and abroad to create a green concrete that will reduce the impact of cement on the environment.

This product has the potential to be used as an alternative to conventional concrete in large-scale constructions such as residential buildings and infrastructure, as well as small-scale constructions such a pavements and brickworks. 

Dr Nagizadeh, whose passion is cement and green concrete, says the idea of eco-friendly concrete was considered by European researchers a few years ago; however, this technology is still in its initial stages and has not been researched and employed at industrial scale yet. He believes that it is due to the complexity of the preparation process, and the relatively aggressive chemicals used in green concrete mixtures.

Expertise and equipment 

With his knowledge and experience of the product, Dr Naghizadeh – who joined EnSci in 2020 – has been appointed project leader of a collaborative group of scientists from the Universities of Johannesburg, KwaZulu-Natal, Yaoundé in Cameroon, and the Erzurum Technical University in Turkey.  

“Since there are only a limited number of researchers in this field, EnSci is benefiting from the expertise of this international collaboration. The proficiency of this group of scientists are keeping the project current, based on the latest findings in the research area,” says Louis Lagrange, Head of the Department of Engineering Sciences. 

Based on this new capacity, the department decided to establish and equip a new laboratory facility dedicated to cement and concrete research, with a specific current focus on green concrete. 

In this laboratory, they want to create formulations of green concrete, based on user-friendly materials. Furthermore, they aim to simplify the preparation and mixing process. “This can introduce a more eco-friendly, desirable product that can easily be employed extensively in the construction industry,” says Lagrange.

Benefits and other advantages

Besides its ability to reduce the impact on the environment through reduced carbon emissions, the product is also described to perform at equal or even superior strength and durability compared to conventional concrete, with potentially substantial environmental and economic benefits. 

This product is also primarily made from waste materials or industrial by-products. Dr Naghizadeh explains it as follows: “Normal concrete consists of conventional (Portland) cement, sand, stone and water, while in green concrete the conventional cement part of the concrete mix is replaced by industrial wastes or by-products and alkali solutions. These alternative materials are mostly aluminosilicate materials such as fly ash (residue from coal burning process in power plants) and slag (waste material from iron extraction processes).”

“Using these waste substances as binding material in green concrete can, apart from the environmental benefits, also reduce waste and contribute to the circular economy. Annually, more than 36 million tons of fly ash are produced in South Africa alone, of which more than 90% is deposited at landfill sites. Reuse of these waste materials will moderate the related waste deposition issues, such as air and groundwater pollution.”

Production of green concrete

Currently, green concrete is mostly produced in two parts: a solid raw material and an alkali activation solution. With their project, the research group wants to develop green concrete in a powdered form, to be mixed with water, instead of a chemical. Dr Nagizadeh estimates that the construction industry will be able to benefit from their work in about two years’ time when they will have a user-friendly green concrete product ready. 

Apart from putting an eco-friendlier concrete on the market, this project is also establishing a brand-new research niche in the UFS Department of Engineering Sciences. According to Lagrange, this research has the ability to attract postgraduate students and other researchers. He is also looking forward to the international academic recognition that EnSci will receive through published articles in leading international journals, and the participation of researchers in accredited conferences arising from this project. 

Lagrange is pleased that the project is establishing EnSci as a research player of note in the engineering field, specifically in the green engineering field. 

News Archive

NRF grants of millions for Kovsie professors
2013-05-20

 

Prof Martin Ntwaeaborwa (left) and Prof Bennie Viljoen
20 May 2013


Two professors received research grants from the National Research Foundation (NRF). The money will be used for the purchase of equipment to add more value to their research and take the university further in specific research fields.

Prof Martin Ntwaeaborwa from the Department of Physics has received a R10 million award, following a successful application to the National Nanotechnology Equipment Programme (NNEP) of the NRF for a high-resolution field emission scanning electron microscope (SEM) with integrated cathodoluminescence (CL) and energy dispersive X-ray spectrometers (EDS).

Prof Bennie Viljoen from the Department of Microbial, Biochemical and Food Biotechnology has also been awarded R1,171 million, following a successful application to the Research Infrastructure Support Programme (RISP) for the purchase of a LECO CHN628 Series Elemental Analyser with a Sulphur add-on module.

Prof Ntwaeaborwa says the SEM-CL-EDS’ state-of-the art equipment combines three different techniques in one and it is capable of analysing a variety of materials ranging from bulk to individual nanoparticles. This combination is the first of its kind in Africa. This equipment is specifically designed for nanotechnology and can analyse particles as small as 5nm in diameter, a scale which the old tungsten SEM at the Centre of Microscopy cannot achieve.

The equipment will be used to simultaneously analyse the shapes and sizes of submicron particles, chemical composition and cathodoluminescence properties of materials. The SEM-CL-EDS is a multi-user facility and it will be used for multi- and interdisciplinary research involving physics, chemistry, materials science, life sciences and geological sciences. It will be housed at the Centre of Microscopy.
“I have no doubt that this equipment is going to give our university a great leap forward in research in the fields of electron microscopy and cathodoluminescence,” Prof Ntwaeaborwa said.

Prof Viljoen says the analyser is used to determine nitrogen, carbon/nitrogen, and carbon/hydrogen/nitrogen in organic matrices. The instrument utilises a combustion technique and provides a result within 4,5 minutes for all the elements being determined. In addition to the above, the machine also offers a sulphur add-on module which provides sulphur analysis for any element combination. The CHN 628 S module is specifically designed to determine the sulphur content in a wide variety of organic materials such as coal and fuel oils, as well as some inorganic materials such as soil, cement and limestone.

The necessity of environmental protection has stimulated the development of various methods, allowing the determination of different pollutants in the natural environment, including methods for determining inorganic nitrogen ions, carbon and sulphur. Many of the methods used so far have proven insufficiently sensitive, selective or inaccurate. The availability of the LECO analyser in a research programme on environmental pollution/ food security will facilitate accurate and rapid quantification of these elements. Ions in water, waste water, air, food products and other complex matrix samples have become a major problem and studies are showing that these pollutants are likely to cause severe declines in native plant communities and eventually food security.

“With the addition of the analyser, we will be able to identify these polluted areas, including air, water and land pollution, in an attempt to enhance food security,” Viljoen said. “Excess levels of nitrogen and phosphorous wreaking havoc on human health and food security, will be investigated.”

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