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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

Workplace discrimination and unfair practices explored in new book
2017-09-13

 Description: Denine read more Tags: Denine Smit, Labour law, employee relations, bullying, vulnerability, research, Damain Viviers 

Dr Denine Smit
Photo: Supplied

Two law scholars, Dr Denine Smit and Dr Damian Viviers, from the Faculty of Law at the University of the Free State (UFS) recently launched a book titled Vulnerable Employees, which was inspired by their interest in researching, creating awareness and providing a legal exposition in relation to employees who are vulnerable and experience prejudice and dignity violations in the workplace. These include workplace bullying, appearance-based discrimination, those who are gender fluid or have mental-health conditions.
“Dr Viviers, who is also a former student of mine, and I, have been working together for years and share a common understanding in relation to our various topics of interest. We often share the same train of thought. This is how we came to work together to produce this book,” said Dr Smit.


Research focused on employee challenges in the workplace

The book expands on the field of knowledge regarding certain categories of employees who, as a consequence of various mutable, immutable and semi-immutable characteristics, as well as behavioural experiences, are rendered vulnerable in their employment relationships. The book draws on various social, psychological and other empirical considerations, as well as comparative legal research from foreign and international law, in order to expand on the legal position under the South African legal framework governing these conditions. While the book first and foremost constitutes a compendium of research to be used for this purpose, it also serves as a practical guide for all legal practitioners, human resources managers, other labour stakeholders and the judiciary.

Book draws strength in other academic fields
Vulnerable Employees was launched on 28 July 2017 at the UFS library, to an audience of academics and students, with a panel discussion made up of the authors and two other panellists. One of the panellists was Dr Katinka Botha, a leading psychiatrist in the Free State who has a wealth of experience in this field. “Her selection as a panellist was motivated by the various significant inter-disciplinary considerations and intersections between psychology, psychiatry and law, contained in the book,” said Dr Smit. 
“Dr Botha’s expertise was invaluable in shedding light on mental-health considerations during the panel discussion.” 
Mr Lesley Mokgoro, the other panellist, is a leading labour law practitioner, as well as director and head of the Dispute Resolution Practice Group at Phatshoane Henney Attorneys. “His years of experience working with all role players in the employment domain, as well as his extensive legal knowledge and expertise, made him uniquely qualified to serve on the panel and deliver an opinion of the practical and academic value of the book,” said Dr Smit.


Workplace policies key to securing employee rights

There are a number of growing trends in the workplace that could shape the practice of labour law or workplace policies. Dr Smit said the need for employers to regulate workplace culture, particularly in relation to bullying, harassment and unfair discrimination, in line with the South African legal framework, was a fundamental need in all workplaces. Effective workplace policies may be used to clearly outline the relevant “dos and don’ts” to employees, as well as the procedures and processes that may be followed in order to address such conduct. Workplace policies serve to advance legal certainty and efficiency, since the rights and obligations of all role players are clearly demarcated, or should be, in terms of a well-drafted and considered policy. 
The book is one of several publications produced by Dr Smit in collaboration with Dr Viviers on the topic of workplace discrimination and the law. The two scholars are working on another book to be published at the end of 2017.

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