Modelling the pressure dependence and the influence of added polymeric fibers on the permeability of refractory concretes

In order to facilitate the water evacuation during drying, polymeric fibers are added to refractory concretes. A permeability model using Bruggeman's approach is developed to predict the permeability increase due to the fibers addition. This model (without adjustable parameters) knowing the fibers geometry (given by the manufacturer) and added amount (mass fraction varying between 0 and 0.20%) is validated by a thorough comparison with experimental results. The refractory permeability is measured at ambient temperature varying the quantity of added organic fibers after the samples were fired at different temperatures (from 80 °C to 500 °C). The analysis of results is especially careful to take into account the influence on the permeability, on both pressure (Klinkenberg effect) and firing temperature. The agreement between theoretical and experimental results is shown to be very satisfactory.