The University of the Free State (UFS) Department of Engineering Sciences' green concrete project aims to produce user-friendly geopolymer concrete by eliminating aggressive alkali activator additives from the mixtures, says lecturer and project leader Dr Abdolhossein Naghizadeh.
The potential product will be formulated by optimising mixture parameters and ingredients based on the South African industrial by-products. The green concrete project involves research aimed at producing environment-friendly concrete based on industrial waste materials.
In green concrete mixtures, geopolymer is used as the binder. Geopolymer binders consist of two components comprising solid raw material and a liquid alkali activator.
Once the raw material is mixed with an alkali activator, the hardening process starts. To obtain high strengths, the mixture is exposed to elevated temperatures of between 40 °C and 80 °C for up to 24 hours.
Although geopolymer concrete technology has been employed in limited projects in countries such as China, Australia, France and the US, there are some issues regarding the complexity of this technology that need to be solved before its extensive application in the industry. It may take some time before this ‘new’ concrete will be used more regularly in the construction industry, explains Naghizadeh.
“The main objective of green concrete technology is to minimise the environmental impact caused by normal cement, but consuming green concrete based on a geopolymer binder system can also provide economic benefits by using waste materials, as well as minimising energy consumption. The reuse of industrial waste materials such as fly ash would help with waste management in power stations,” he notes.
The technology of geopolymer binder as an alternative cement was introduced to the academic world a few years ago. However, there are some issues that greatly hinder its application in the industry.
Some of these issues are related to the mixing design complexity, the aggressiveness of the activators used, the diversities of raw materials found in different countries and special curing procedures required for this type of concrete.
Based on the significance of the research topic, as well as the existing research capacity in the UFS Department of Engineering Sciences, the research committee decided to play a role and contribute to the ongoing development of the new technology, known as geopolymer concrete or green concrete.
“The project aims of this laboratory are to create formulations of green concrete based on user-friendly materials and the simplification of the preparation and mixing process. This could introduce a more eco-friendly, desirable product that can be easily employed extensively in the construction industry,” explains Naghizadeh.