Hygrothermal properties of glass fiber reinforced cements subjected to elevated temperature

The effect of elevated temperatures on basic hygric and thermal properties of three types of glass fiber reinforced cement composites (GFRC) is analyzed in the paper. The main difference in the composition of particular GFRC is the use of wollastonite and vermiculite in two of them instead of usual sand aggregates. The composites containing wollastonite and vermiculite are found to have about four times lower thermal conductivity and two to three times lower thermal diffusivity in room temperature conditions. After heating the samples to 800DGC and subsequent cooling, a decrease in room-temperature thermal conductivity as high as 50% and an increase in moisture diffusivity in the range of one to two orders of magnitude are observed for all types of studied materials. The application of wollastonite and vermiculite exhibits a positive effect on the high temperature linear thermal expansion coefficient. On the other hand, for temperatures higher than 450DGC the thermal diffusivity of materials with wollastonite and vermiculite is higher than of common GFRC with sand aggregates.