Composites based on alternative raw materials at high temperature conditions

Abstract

This paper presents newly developed polymer-cement composites. The primary binder (cement) was partially substituted by use of blast-furnace slag and high-temperature fly ash. A lightweight aggregate – agloporite (grain size in range 1–2 mm) was used among other components. This porous aggregate is produced from energy by-products (fly ash). Attention was focused on the behavior of the composites when exposed to elevated temperatures (400 °C–1,000°C). The influence of several different methods of temperature decrease was assessed – slow (in furnace 1°C/min) and rapid (laboratory ambient 22°C and water bath 18°C). Specific dimensional changes were determined, including strength characteristics and bulk density. Structural deterioration and microstructural changes of selected specimens were investigated by analytical techniques (SEM and CT). Compressive and bending tensile strength changed variously depending on temperature changes, including several cooling conditions. Deterioration reactions (especially cracks) which were formed in investigated composite structures corresponded with results of physico-mechanical testing. That was confirmed by using the CT and SEM. The fact that the agloporite has a positive effect on thermal resistance of developed polymer-cement composites was proved. Almost no cracks or other failures were identified (by using CT and SEM) in interfacial transition zones of agloporite after thermal stress. This indicates very good bond adhesion between the matrix and the porous aggregates during extreme temperature conditions (in case of different cooling methods).