Abstract

The research was initiated to assess the influence of Circulating Fluidized Bed Combustion (CFBC) fly ash on the modulus of elasticity, the compressive strength, the bending strength of mortars and the compressive strength of concretes. The objective was to examine possibilities of using the CFBC fly ash in structural concrete. The range of materials included mechanically activated fly ash coming from combustion of hard coal in two different fluidized bed combustion boilers. Several concrete and mortar mixes were designed with constant water to binder ratio and in each mix a part of cement was substituted by CFBC fly ash. In case of mortars the substitution of 20 and 35% of cement weight was applied, whereas in concrete fly ashes were used as 20, 30 and 40% replacement of cement weight. After 7, 28 and 90 days of curing the modulus of elasticity, the bending strength and the compressive strength of mortar as well as the compressive strength of concrete were tested. Obtained results revealed a significant influence of used additive on elastic and strength properties of investigated materials as well as on concrete mix behavior.