Characterization of the Influence of Fly Ash on the Durability of Cementitious Matrix Materials

The aim of this work is, on the one hand, to study the influence of fly ash on the durability of cementitious matrices through measurements of the coefficient of water absorption by capillarity and the porosity accessible to water on standardized mortar specimens in which Lafarge CEM II/32.5R cement has been substituted by fly ash (0%, 5%, 10% and 20%). And secondly, to characterize the influence of certain concrete parameters such as true cement class, E/C ratio, average compressive strength, relative humidity, granular coefficient and exposure coefficient on the kinetics of carbonation depth using the Oxand model, which is essentially based on Fick's law in porous media. The results obtained showed, on the one hand, a decrease in the water absorption coefficient and in the porosity accessible to water when the ash content increases and, on the other hand, a decrease in the carbonation depth when the cement's true class, average strength and granular coefficient increase. And a decrease in carbonation depth with decreasing W/C ratio and exposure coefficient. The results also show that carbonation depth is greatest when the relative humidity of the surrounding environment is between 40% and 60%. Keywords: Durability, cementitious matrix, absorption, porosity, carbonation, fly ash