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Green Engineering: How UFS’s Green concrete can be an alternative to OPC cement

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

Statement on protest at the UFS

2005-03-04

Following a protest by student and non-student organisations today, the management of the University of the Free State (UFS) would like to place the following facts on record:

1. There is a well-documented process underway to further transform the UFS. At the official opening of the UFS on 4 February 2005 , the Rector and Vice-chancellor, Prof Frederick Fourie, announced that the UFS would draft a comprehensive Transformation Plan to guide the next phase of transformation at the institution.

The UFS appeals to student formations, staff associations, trade unions and other role-players to make a constructive input into this Transformation Plan.

The UFS management has been - and always will be - willing to engage with role-players and is prepared to do so even after today’s protest.

2. There is thus no regulation or policy prescription which separates students in hostels according to race.

The reality is that students exercise their freedom of choice as to which hostel they wish to be placed in. This was agreed upon by black and white students in 1997/8.

However, the unintended consequence and practice of this hostel placement policy has been that students themselves have tended to choose to stay in hostels which have over time become black hostels and white hostels.

This is a matter of concern for the management of the UFS as such a situation does not promote interaction across language, cultural and socio-economic groupings of students.

This matter is receiving attention and an intensive consultative process, which will include students, will be launched to review this policy.

The management is convinced that such interaction will enhance the learning experience of all students and sensitise them to the reality of a multicultural South Africa and a multicultural world.

3. No student organisation has been banned from operating at any of the three campuses of the UFS.

In the past few weeks, SASCO, the Young Communist League and the ANC Youth League (ANCYL) have held meetings on all three campuses, namely the Qwaqwa campus, the Vista campus and the main campus.

There are also regular interactions between top management and the leadership of SASCO and the ANCYL on campus.

In fact, the UFS upholds the right of students and staff to associate freely and to organise themselves as they see fit.

The UFS also upholds the rights of staff and students to engage in legal and peaceful protests.

The management however remains committed to discussing issues that affect staff and students in a constructive manner and appeals to student organisations in this case to engage with management.

4. The issues of registration, fees, debt and financial aid are continually monitored, and interventions to assist students are made regularly. To assist as far as possible those academically deserving students who face financial difficulties, the UFS management has put in place a structure called the Monitoring committee that includes management and student representatives.

The purpose of the Monitoring Committee is to review the cases of individual students to determine how best they can be assisted.

This applies to the Qwaqwa campus, the Vista campus and the main campus.

It is generally the case that students who perform academically will not have any difficulty in obtaining financial assistance. However, according to the requirements of National Student Financial Scheme, students who perform poorly will have difficulty in obtaining such assistance.

5. With regard to student governance, the process to institute an inclusive Central Student Representative Council (SRC), on which all three campuses will be equitably represented, was launched in July 2004, and a preliminary constitution has just been drafted. At the same time an inclusive process to review certain elements of the constitution of the main campus SRC was initiated at the end of 2004. This process, which includes all relevant student organisations and structures, is planned to produce an outcome within the next couple of months.

6. There is no policy at the UFS that is based on racism or that discriminates on the basis of the race of students and staff.

As part of the building of a new institutional culture within the broader transformation process, the UFS management is determined to eradicate all elements of racism that may occur on its campuses, and has already instituted inclusive forums on campus to discuss the issue of values and principles for a non-racial university.

Issued by: Mr Anton Fisher
Director: Strategic Communication
Cell: 072 207 8334
Tel: (051) 401-2749
4 March 2005

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