30th Our World in Concrete and Structures (OWICs) - 2005
M. Akram Tahir*, UET, Lahore, Pakistan
M. Sabir, Pakistan Railways, Lahore, Pakistan
Chemical attack, fly ash-cement mortars, resistance to sulfate attack, permeability.
The inclusion of fly ash as a component of concrete either as an admixture to the
cement or as partial replacement of cement imparts significant enhancement to the
basic characteristics of the resulting concrete, both in its fresh and hardened state.
The objective of this study was to investigate the effects on the selected aspects of
durability of mortars incorporating locally produced fly ash. The resistance of fly ashmortars to the acid and sulfate attack is covered in this paper. Two series of mortars
were prepared by replacing 20% to 60% of cement with fly ashes obtained from two
different sources. Three water-binder ratios of 0.4, 0.475, and 0.55 were used. The
specimens prepared in accordance with ASTM C-267 and cured for 56 days were
separately exposed to 0.5% Sulfuric acid solution and 0.5% Hydrochloric acid
solution. The results of this study indicated that the resistance to acid attack of
mortars containing fly ash up to 30% was better than or similar to that of the control
mortars. The increase in water/binder ratio however has shown adverse effect on the
chemical resistance of the mortars. It was concluded from this study that both the fly
ashes improved the resistance of mortars to sulfate attack and this resistance was
increased with fly ash inclusion up to about 40%. However an increase in waterbinder
ratio impaired the resistance to sulfate attack.