Multi-objective optimization of the flow condition of binary constituent net-zero concretes towards carbon neutrality-built environment pathway

The era of sustainability in the built environment is upon us and the production and usage of cement is being suppressed in line with the requirements of the United Nations Sustainable Development Goals (UNSDGs) and recently those of the conference of the parties of 27th united nations climate change (COP27). This is in agreement with the carbon-neutrality pathway for the year 2050, where greenhouses gas (GHG) emissions and carbon footprint originating from cement production and its usage in the concrete-built environment is reduced to zero. Efforts are in top gear by the concrete production expert and users to replace the use of cement with more ecofriendly cementitious materials. In this research paper, a multi-objective optimization exercise has been reported, which used machine learning (ML) techniques to predict the net-zero concrete (NZC) slump flow (SF) and slump height (SH) of fly ash (FA)- and blast furnace slag (BFS)-based concrete from a data point of 103 concrete mixes. It was reported in the literature that the increase in the addition of the binary combination of FA and BFS reduced the cement content in concrete and improved its workability and rheological behaviour. This in turn reduced the emissions of CO 2 . Also, the BFS was used as a replacement for the fine aggregate, which reduced the energy needed for its production and CO2 footprint associate with it. The results of the model showed that the artificial neural network (ANN) outclassed the other two techniques in forecasting SF with R 2 of 0.939, sum of squared error (SSE) of 441, mean squared error (MSE) of 3.92 mm, mean average error (MAE) of 1.72 mm and root mean squared error (RMSE) of 1.98 mm and SH with R 2 of 0.895, SSE of 3028, MSE of 26.85 mm, MAE of 4.01 mm and RMSE of 5.18 mm. With the ANN as the decisive model with good performance, it becomes imperative to use ANN to predict the design and production of the concrete mixed with FA and BFS as ecofriendly supplementary cementitious additives in terms of concrete workability.