Partners

Abstract:
DTA method was used to follow the hydration process of cement admixtures containing fluidized bed combustion by-product, formed on joined combustion and desulphurisation in some installations with fluidized bed. Based on endothermic peaks attributed to the dehydration of phases formed on hydration, the conditions leading to the formation of so-called ‘delayed’ ettringite were found. This calcium alumino-sulphate hydrate is responsible for lower durability of fluidized bed ash containing material. DTA method is also beneficial in the studies of fluidized bed combustion by-product itself, giving information about the un-burnt carbon content and pozzolanic properties.

Keywords:
DTA, fluidized bed combustion fly ash, hydration

Abstract:
The objective of the investigation was to evaluate the effectiveness of pozzolanic materials to improve durability of glass fibre reinforced cement composites manufactured by premix technique The pozzolanic materials included silica fume, fly ash and metakaolin, a product of tliermal treatment of locally available kaolin. Four point bending tests were performed to evaluate the strength and the flexural toughness of the composites, both in the short term and afler accelerated aging in warm water. Scanning electron microscopy was also applied to identify effects of pozzolanic additives on durability of glass fibres in cement matnx. A replacement of 10% of cement by metakaolin resulted in a high level of long-term flexural strength and retention of large portion of strain hardening behaviour of composites.

Keywords:
composite materials, durability, glass fibre cement, metakaolin, pozzolanic materials