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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

Stem cell research and human cloning: legal and ethical focal points
2004-07-29

   

(Summary of the inaugural lecture of Prof Hennie Oosthuizen, from the Department of Criminal and Medical Law at the Faculty of Law of the University of the Free State.)

 

In the light of stem cell research, research on embryo’s and human cloning it will be fatal for legal advisors and researchers in South Africa to ignore the benefits that new bio-medical development, through research, contain for this country.

Legal advisors across the world have various views on stem cell research and human cloning. In the USA there is no legislation that regulates stem cell research but a number of States adopted legislation that approves stem cell research. The British Parlement gave permission for research on embryonic stem cells, but determined that it must be monitored closely and the European Union is of the opinion that it will open a door for race purification and commercial exploitation of human beings.

In South Africa the Bill on National Health makes provision for therapeutical and non therapeutical research. It also makes provision for therapeutical embryonical stem cell research on fetuses, which is not older than 14 days, as well as for therapeutical cloning under certain circumstances subject to the approval of the Minister. The Bill prohibits reproductive cloning.

Research on human embrio’s is a very controversial issue, here and in the rest of the world.

Researchers believe that the use of stem cell therapy could help to side-step the rejection of newly transplanted organs and tissue and if a bank for stem cell could be built, the shortage of organs for transplants would become something of the past. Stem cells could also be used for healing of Alzheimer’s, Parkinson’s and spinal injuries.

Sources from which stem cells are obtained could also lead to further ethical issues. Stem cells are harvested from mature human cells and embryonic stem cells. Another source to be utilised is to take egg cells from the ovaries of aborted fetuses. This will be morally unacceptable for those against abortions. Linking a financial incentive to that could become more of a controversial issue because the woman’s decision to abort could be influenced. The ideal would be to rather use human fetus tissue from spontaneous abortions or extra-uterine pregnancies than induced abortions.

The potential to obtain stem cells from the blood of the umbilical cord, bone-marrow and fetus tissue and for these cells to arrange themselves is known for quite some time. Blood from the umbilical cord contains many stem cells, which is the origin of the body’s immune and blood system. It is beneficial to bank the blood of a newborn baby’s umbilical cord. Through stem cell transplants the baby or another family member’s life could be saved from future illnesses such as anemia, leukemia and metabolic storing disabilities as well as certain generic immuno disabilities.

The possibility to withdraw stem cells from human embrio’s and to grow them is more useable because it has more treatment possibilities.

With the birth of Dolly the sheep, communities strongly expressed their concern about the possibility that a new cloning technique such as the replacement of the core of a cell will be used in human reproduction. Embryonic splitting and core replacement are two well known techniques that are associated with the cloning process.

I differentiate between reproductive cloning – to create a cloned human embryo with the aim to bring about a pregnancy of a child that is identical to another individual – and therapeutically cloning – to create a cloned human embryo for research purposes and for healing human illnesses.

Worldwide people are debating whether to proceed with therapeutical cloning. There are people for and against it. The biggest ethical objection against therapeutical cloning is the termination of the development of a potential human being.

Children born from cloning will differ from each other. Factors such as the uterus environment and the environment in which the child is growing up will play a role. Cloning create unique children that will grow up to be unique individuals, just like me and you that will develop into a person, just like you and me. If we understand this scientific fact, most arguments against human cloning will disappear.

Infertility can be treated through in vitro conception. This process does not work for everyone. For some cloning is a revolutionary treatment method because it is the only method that does not require patients to produce sperm and egg cells. The same arguments that were used against in vitro conception in the past are now being used against cloning. It is years later and in vitro cloning is generally applied and accepted by society. I am of the opinion that the same will happen with regard to human cloning.

There is an argument that cloning must be prohibited because it is unsafe. Distorted ideas in this regard were proven wrong. Are these distorted ideas justified to question the safety of cloning and the cloning process you may ask. The answer, according to me, is a definite no. Human cloning does have many advantages. That includes assistance with infertility, prevention of Down Syndrome and recovery from leukemia.

 

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