Study unveils fly ash geopolymer concrete as potential SCM

A new study from Zhejiang University of Technology, China, sheds light on the potential of fly ash geopolymer concrete (FAGC) as a sustainable alternative to Portland cement concrete (PCC), which is a significant contributor to CO₂ emissions. The research, published in *PLOS ONE*, outlines a robust method for predicting the compressive strength of FAGC while optimising its mixture design to minimise environmental impact.

Supplementary cementitious materials (SCMs), such as fly ash, are increasingly used to reduce the clinker content in cement, which in turn lowers CO₂ emissions during production. As an SCM, FAGC leverages fly ash to replace traditional cement binders, offering a more sustainable option for concrete manufacturing. The study highlights the development of an advanced compressive strength prediction model using a large dataset of 1136 observations. By integrating factors such as fly ash characteristics, mixture proportions, and curing parameters, the research employs polynomial regression, genetic programming, and ensemble learning to deliver highly accurate predictions. The ensemble learning model achieved superior accuracy, with an RMSE value of 1.81MPa and an R² value of 0.93.

The researchers also introduced a life cycle assessment-based CO₂ emissions model, demonstrating the environmental benefits of FAGC. A case study revealed that this optimised approach resulted in a 16.7 per cent reduction in CO₂ emissions for FAGC with a compressive strength of 50MPa, compared to traditional design methods. Additionally, FAGC showed a remarkable 60.3 per cent reduction in CO₂ emissions compared to conventional PCC.

"This work provides engineers with tools for compressive strength prediction and low-carbon optimisation of FAGC, enabling rapid and accurate design of concrete with lower CO₂ emissions and greater sustainability," the research team concluded.

This advancement offers engineers a significant step forward in producing similar-strength building materials that emit less CO₂ during production, ultimately contributing to a more sustainable built environment with a lower overall environmental impact.