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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

Student leaders 2012/13 announced

2012-08-30

Ready for the task - Sabelo Khumalo, SRC President of the Qwaqwa Campus and William Clayton, SRC President of the Bloemfontein Campus.
Photo: Johan Roux
31 August 2012

The 2012/13 elections for the Student Representative Councils (SRC) of the University of the Free State were completed successfully and show meaningful support for the changes in student governance adopted by students across campuses over the past two years.

The SRC elections at the Qwaqwa Campus were completed on 23 August 2012, while the elections at our Bloemfontein Campus took place on 27 and 28 August 2012.

The SRC Elections at our Bloemfontein Campus showed a voter turnout of 4516 votes (30.8%), with the elections at the Qwaqwa Campuses showing 1753 votes (46%) – both campuses reached the required quorums and the IEA (Bloemfontein Campus) and IEC (Qwaqwa Campus) declared the elections free and fair and announced the results as a true reflection of the will of the student bodies at the campuses.

The full SRC at Bloemfontein Campus now consists of 62% black and 38% white, and 53% female and 47% male members.

In the Qwaqwa elections, SADESMO achieved 46, 38% of the vote, with SASCO, PASMA and NASMO each achieving 30,23% and 8,39% and 14,26%, respectively.

The successful elections at Bloemfontein Campus show that the detailed transformation of student governance introduced by students at the Campus in 2010 and adopted by the university in 2011, succeeded in mobilizing greater participation of students in governance and representation. These changes in the main included a shift to independent candidacy for elective portfolios (12 seats) and organizational candidacy in nine sub-councils that holds ex officio seats on the SRC. Changes also included the establishment of student representative seats in faculty governance and management forums and the adoption of a reviewed Central SRC Constitution. Ex officio seats hold full and equal constitutional authority in the SRC.

Students at Qwaqwa Campus introduced additional portfolios to its SRC, including ex-officio seats for academic affairs, arts and culture, commuter students, Rag Community Service, religious affairs, residences and sports.

A joint sitting of the Campus SRCs will establish the Central SRC 2012/13 on 9 September 2012.

As a further opportunity for participation in and the development of student governance and representation, the current Central SRC herewith also announces its recent adoption of a student governance advisory programme, namely the UFS Student Elders Council (SEC).

The SEC is established as a combined programme between the Central SRC and the Dean of Student Affairs and will consist of selected senior student leaders from all campuses who completed their terms of office, apply and are appointed to the Elders Council by the Central SRC.

The Council will serve as an advisory structure to the Central SRC and other student structures in support of the continuous development of student governance and representation of the student body at the university.

The SEC will advise the Central SRC to be constituted following the constitution of the respective Campus SRCs.

The SRC members at the Bloemfontein Campus are:

President: Mr William Clayton

Vice-President: Mr Bonolo Thebe

Secretary: Ms Karis-Robin Topkin

Treasurer: Mr Pieter Coetzee

Arts & Culture: Ms Chanmari Erasmus

Accessibility & Student Support: Ms Gene McCaskill

First-generation Students: Ms Tanya Calitz

Legal and Constitutional Affairs: Ms Nokuthula Sithole

Media, Marketing & Liaison: Ms Neo Chere

Sport: Mr Tshepo Moloi

Student Development & Environmental Affairs: Ms Thabisile Mgadi

Transformation: Ms Koketso Mofokeng

Dialogue & Ex officio: Associations Council: Mr Anesu Ruswa

Academic Affairs & Ex officio: Academic Affairs Council: Ms Nombuso Ndlovu

Residence Affairs & Ex officio: Residences Council: Mr Johann Steyn

City Residence Affairs & Ex officio: Commuter Council: Mr Michael van Niekerk

Postgraduate Affairs & Ex officio: Postgraduate Council: Mr Fadeyi Akinsuyi

International Affairs & Ex officio: International Council: Ms Tumelo Moreri

Student Media Affairs & Ex officio: Media Council: Mr Jamal-Dean Grootboom

RAG Community Service & Ex officio: RAG Fundraising Council: Mr Jaco Faul

RAG Community Service & Ex officio: RAG Community Service Council: Ms Keneue Mahloana

The SRC members at the Qwaqwa Campus are:

President General: Mr S Khumalo

Deputy President: Mr P T Lenka

Secretary General: Mr D Khethang

Treasurer General: Mr S I Sithole

Media & Publicity: Mr S N Ntombela

Politics & Transformation: Tbc

Student Development & Evironmental Affairs: Tbc Academic Affairs: Mr T Molawude

Arts & Cultural Affairs: Mr T Nkohli

Off-Campus Students: Mr B Mtshali

RAG, Community Service & Dialogue: Ms S F Mlotya

Religious Affairs: Ms D C Khau

Residence & Catering Affairs: Ms Z Mzolo

Sports Council: Mr S Mngomezulu

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