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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

An education system based on hope is what South Africa needs – Dr Beryl Botman
2016-05-26

Description: Hope revised Tags: Hope revised

Dr Beryl Botman, a postdoctoral research
fellow at the IRSJ, with Dr Willy Nel research associate
at the IRSJ and lecturer at the UFS
Faculty of Education.

HOPE is tangible and concrete construct that should be rooted in the learning and training of teachers,” said Dr Beryl Botman, a postdoctoral research fellow at the Institute for Reconciliation and Social Justice (IRSJ).

She presented her research paper Educators, praxis, and hope: A philosophical analysis of post-apartheid teacher education policy, based on the theoretical ideologies of Paulo Freire’s Pedagogy of the Oppressed. She explores ways in which oppression has been justified, and how it has been overcome through a mutual process between the oppressor and the oppressed, drawing on Paolo Freire’s theories and practices. The presentation was held at the University of the Free State’s (UFS) Faculty of Education, on the Bloemfontein campus on 13 May 2016.

From oppression to hope

Hope should be an educational construct for teacher education in South Africa. Dr Botman asserts that epistemology and ontology should be inseparable, as they are pivotal to an education system that is transformational.

The recent country-wide student protests and demonstrations are an indicant that education institutions need to seek understanding of mechanisms that fuel social conflict. Dr Botman claims that vast social inequalities make the process of democratisation difficult thus hindering transformation. She states that a critical consciousness is important for all South Africans, but more so for educators; it can be used as a tool to understanding the mechanisms of social conflict.

“Self-reflection and self-critique is vital for educators, we need to understand that we do not have all the answers because we ever-evolving beings, working on understanding ourselves and the people around us,” said Dr Botman.

The notion of hope
“I am a farmer. I have no hope for a future that is different from today. This quotation comes from Paulo Freire’s work," said Dr Botman. She said that the South African context and environment is similar. She said that people cannot live for today; one should live for tomorrow if hope is to manifest itself.

South African education environment needs to adopt a progressive consciousness that is future orientated, “You need to be hopeful, if you are radical. You need to be able to envision a new society and a new world,” said Dr Botman.

“You cannot only denounce the present, you need to also announce your hopes for a new society. South Africa needs education systems built on understanding. Although change is difficult, it is necessary for transformation,” Dr Botman added.

What makes hope educational?
“Hope is a vision for a tomorrow that is different, and vital for a transformative education system. To get out of a state of despair, people need to educate their hope. Lately, the issue of white privilege has been brought to the fore. You need to educate your hope, so that you understand the reality of others but, more importantly, of yourself,” said Dr Botman.

Dr Botma added that teacher education needs to adopt a Freirean pedagogy with a strong philosophy based on hope. The agency of teachers can either be hopeful or without hope. It is vital that education promotes hope.

“Teachers need to rely on their existential experience, the experiences of others, and the experiences of the children or students they teach. An understanding of all these experience reinforces the idea that people are life-long learners, always learning and adapting to society’s needs,” said Dr Botman.

Teachers as agents of hope

Dr Botman stated that current South African education policy is directed towards transformation but it does not stipulate means to achieve this objective. Further, she argues that educators need to put greater emphasis on self-knowledge, self-reflection, and self-education. Connecting with teachers, parents, students and the community engages with their self-knowledge and reflection.

Reorientation of teacher education
Dr Botman concluded by mentioning that rethinking ontological and epistemological aspects of education is important, and should be a pivotal point of teacher education. A renewed vision of hope-orientated philosophy and pedagogy needs to be adopted by the education institutions. A praxis, which is an informed action, when a balance between theory and practice is achieved. There is a need for an inclusive exploration of education philosophies and education systems not only European and Western but also African and Eastern as well.

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