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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

Early nutrition impacts on burden of disease
2017-11-15


 Description: Corinna Walsh read more Tags: Corinna Walsh read more

Prof Corinna Walsh during her inaugural lecture on ‘Nutrition in Transition’.
Photo: Stephen Collett 

“The first 1 000 days, from conception to two years, is a critical time to ensure that the early environment is optimal to guarantee the best outcomes,” Prof Corinna Walsh, Professor in the Department of Nutrition and Dietetics at the University of Free State (UFS), said. She delivered her inaugural lecture on Nutrition in Transition on 30 October 2017. 

During her lecture, Prof Walsh explained how an unfavourable early environment impacts on the health and well-being of both children and adults. She gave an overview of the prevalence of hunger and food insecurity in the Free State, and described the shift that has occurred from healthier traditional diets to more unhealthy Western diets accompanied by sedentary lifestyles. These patterns are closely linked to the triple burden of malnutrition, including undernutrition, micro-nutrient malnutrition, and obesity. Finally, Prof Walsh highlighted the double burden of disease, focusing on chronic lifestyle diseases on the one hand, and infectious diseases such as HIV/AIDS and TB on the other hand.

“Preparing for this lecture has given me the opportunity to reflect on the almost thirty years of my research journey, a process that I thoroughly enjoyed,” said Prof Walsh.

“It was a privilege to share the work of my research team with fellow colleagues as well as with family and friends,” she said. Prof Walsh is a National Research Foundation C-rated researcher and also served on the Board of the Medical Research Council from 2005 to 2010.

Foundations for health, growth established early
The first 1 000-day window focuses on the time between conception and the second birthday. “This is a critical period for growth and development,” Prof Walsh said. It is a unique period, as the foundations for health, growth, and neuro-development are established. It also focused on the implications of malnutrition, which is the biggest risk factor contributing to the global burden of disease.


Research identifies burden of disease
Her research has made a considerable contribution to identifying the burden of disease in the Free State. “It focuses on both malnutrition and infectious diseases such as HIV and TB on the one hand, and chronic lifestyle diseases such as obesity, diabetes, and hypertension on the other,” she said. The research team have also implemented a number of interventions to address these challenges, including programmes that have assessed the impact of nutrition-education programmes, household food gardens, and nutrition supplementation.

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