Carbonation model for fly ash concrete based on artificial neural network: Development and parametric analysis

Control and prediction of the carbonation depth in reinforced concrete structures has great relevance for construction industry, since the carbonation process is directly related to the service life and durability of these structures. One challenge in carbonation modelling is to understand the complex relation between the main parameters of the phenomenon. An Artificial Neural Network (ANN) may overcome this challenge, finding solutions to these nonlinear and complex problems. In this study, an ANN with backpropagation algorithm is used in predicting the carbonation depth of concretes that contains fly ash addition. A total of 90 ANN topologies are implemented. It was observed in the training process that networks with two hidden layers are able to generate models with determination coefficient greater than 0.8. One of them is select as the one that best fit the problem. The optimized configuration provided smallest root mean square error associated with the best determination coefficient. Besides, the parametric study shown that the parameters that had most influence on the carbonation depth in fly ash-concretes were the cement consumption, fly ash content, CO2 rate and relative humidity. Besides, results indicate that the model can be applied to estimate the lifespan of concrete structures, and may be used as simulation tool in the development of engineering projects focused on durability.