Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
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

Media: Sunday Times
2006-05-20

Sunday Times, 4 June 2006

True leadership may mean admitting disunity
 

In this edited extract from the inaugural King Moshoeshoe Memorial Lecture at the University of the Free State, Professor Njabulo S Ndebele explores the leadership challenges facing South Africa

RECENT events have created a sense that we are undergoing a serious crisis of leadership in our new democracy. An increasing number of highly intelligent, sensitive and committed South Africans, across class, racial and cultural spectrums, confess to feeling uncertain and vulnerable as never before since 1994.

When indomitable optimists confess to having a sense of things unhinging, the misery of anxiety spreads. We have the sense that events are spiralling out of control and that no one among the leadership of the country seems to have a definitive handle on things.

There can be nothing more debilitating than a generalised and undefined sense of anxiety in the body politic. It breeds conspiracies and fear.

There is an impression that a very complex society has developed, in the last few years, a rather simple, centralised governance mechanism in the hope that delivery can be better and more quickly driven. The complexity of governance then gets located within a single structure of authority rather than in the devolved structures envisaged in the Constitution, which should interact with one another continuously, and in response to their specific settings, to achieve defined goals. Collapse in a single structure of authority, because there is no robust backup, can be catastrophic.

The autonomy of devolved structures presents itself as an impediment only when visionary cohesion collapses. Where such cohesion is strong, the impediment is only illusory, particularly when it encourages healthy competition, for example, among the provinces, or where a province develops a character that is not necessarily autonomous politically but rather distinctive and a special source of regional pride. Such competition brings vibrancy to the country. It does not necessarily challenge the centre.

Devolved autonomy is vital in the interests of sustainable governance. The failure of various structures to actualise their constitutionally defined roles should not be attributed to the failure of the prescribed governance mechanism. It is too early to say that what we have has not worked. The only viable corrective will be in our ability to be robust in identifying the problems and dealing with them concertedly.

We have never had social cohesion in South Africa — certainly not since the Natives’ Land Act of 1913. What we definitely have had over the decades is a mobilising vision. Could it be that the mobilising vision, mistaken for social cohesion, is cracking under the weight of the reality and extent of social reconstruction, and that the legitimate framework for debating these problems is collapsing? If that is so, are we witnessing a cumulative failure of leadership?

I am making a descriptive rather than an evaluative inquiry. I do not believe that there is any single entity to be blamed. It is simply that we may be a country in search of another line of approach. What will it be?

I would like to suggest two avenues of approach — an inclusive model and a counter-intuitive model of leadership.

In an inclusive approach, leadership is exercised not only by those who have been put in some position of power to steer an organisation or institution. Leadership is what all of us do when we express, sincerely, our deepest feelings and thoughts; when we do our work, whatever it is, with passion and integrity.

Counter-intuitive leadership lies in the ability of leaders to read a problematic situation, assess probable outcomes and then recognise that those outcomes will only compound the problem. Genuine leadership, in this sense, requires going against probability in seeking unexpected outcomes. That’s what happened when we avoided a civil war and ended up with an “unexpected” democracy.

Right now, we may very well hear desperate calls for unity, when the counter-intuitive imperative would be to acknowledge disunity. A declaration of unity where it manifestly does not appear to exist will fail to reassure.

Many within the “broad alliance” might have the view that the mobilising vision of old may have transformed into a strategy of executive steering with a disposition towards an expectation of compliance. No matter how compelling the reasons for that tendency, it may be seen as part of a cumulative process in which popular notions of democratic governance are apparently undermined and devalued; and where public uncertainty in the midst of seeming crisis induces fear which could freeze public thinking at a time when more voices ought to be heard.

Could it be that part of the problem is that we are unable to deal with the notion of opposition? We are horrified that any of us could be seen to have become “the opposition”. The word has been demonised. In reality, it is time we began to anticipate the arrival of a moment when there is no longer a single, overwhelmingly dominant political force as is currently the case. Such is the course of history. The measure of the maturity of the current political environment will be in how it can create conditions that anticipate that moment rather than seek to prevent it. We see here once more the essential creativity of the counter-intuitive imperative.

This is the formidable challenge of a popular post-apartheid political movement. Can it conceptually anticipate a future when it is no longer overwhelmingly in control, in the form in which it is currently, and resist, counter-intuitively, the temptation to prevent such an eventuality? Successfully resisting such an option would enable its current vision and its ultimate legacy to our country to manifest in different articulations, which then contend for social influence. In this way, the vision never really dies; it simply evolves into higher, more complex forms of itself. Consider the metaphor of flying ants replicating the ant community by establishing new ones.

We may certainly experience the meaning of comradeship differently, where we will now have “comrades on the other side”.

Any political movement that imagines itself as a perpetual entity should look at the compelling evidence of history. Few movements have survived those defining moments when they should have been more elastic, and that because they were not, did not live to see the next day.

I believe we may have reached a moment not fundamentally different from the sobering, yet uplifting and vision-making, nation-building realities that led to Kempton Park in the early ’90s. The difference between then and now is that the black majority is not facing white compatriots across the negotiating table. Rather, it is facing itself: perhaps really for the first time since 1994. Could we apply to ourselves the same degree of inventiveness and rigorous negotiation we displayed leading up to the adoption or our Constitution?

This is not a time for repeating old platitudes. It is the time, once more, for vision.

In the total scheme of things, the outcome could be as disastrous as it could be formative and uplifting, setting in place the conditions for a true renaissance that could be sustained for generations to come.

Ndebele is Vice-Chancellor of the University of Cape Town and author of the novel The Cry of Winnie Mandela

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept