Influence of various types of waste on the main properties of gypsum based composites for thermal insulations

Abstract

In the last decade numerous research studies were performed in the attempt to recycle several types of industrial waste. This study has as main objective the obtaining and characterization of gypsum based composite materials with various amounts of industrial wastes (flue gas desulfurization gypsum and recycled rubber). The main properties assessed for these materials were setting time, compressive strength, apparent density and thermal conductivity. The gypsum binder was partially replaced with thermally treated flue gas desulfurization gypsum (FGDgp_t) without an important negative impact on the compressive strength; if the replacement amount is up to 40 wt.% the resulted binder still meets the requirements imposed for this property by specific norm for gypsum plaster - EN 13279-1. The substitution of gypsum plaster with FGDgp_t shortens the setting time, therefore it was compulsory to use also sodium citrate as retarder addition. The addition of 5 wt.% rubber waste has a positive effect on the thermal conductivity of composite materials based on gypsum binder with/without FGDgp_t. Consequently, these materials could be used for the manufacture of low cost, eco-friendly thermal insulation materials.