Reaction kinetics of basaltic elements in cementitious matrices: theoretical considerations

Abstract

Basalt fibers, the frequently mentioned alternative to those made of steel, possess very good mechanical properties and temperature resistance. The alkaline environment of cement matrix makes it vulnerable due to partial fiber decomposition by the effects of OH- ions. This paper aims at computational modelling of such reactions in order to approximate the course of degradation or to predict it lately. The isothermal reaction models are discussed to reveal their strong/weak points by means of fundamental reaction mechanisms analysis. The shape factor and diffusion-based deceleration of the reactions are mentioned as the most significant ones in that respect. The model accuracy is quantified based on fitting the modelling outputs to reference experimental data. The effect of discussion was found to be the most significant factor as the model fitting reached the lowest RMSE (0.0047). Further application of a diffusion model is therefore recommended. The geometrical models need to have reaction rate reduction explicitly incorporated in the reaction constant, otherwise inapplicable data is produced (RMSE = 0.0193).