This paper presents results on the compressive strength of mortars in which 10 and 20% of ASTM Type I cement has been replaced by ground fly ash from two different sources. The results are compared with those of the mortars made with ASTM Type I cement and with the mortar in which 10% of portland cement has been replaced by silica fume. The results show that the mortars made with 20% replacement of cement by the fine Sundance fly ash that had been ground for 2 hours achieved a 28-day compressive strength that was 90 to 93% of the strength of the mortars incorporating 10% silica fume as cement replacement. However for the coarse fly ash the results were not encouraging: even increasing the grinding times of the fly ash up to 10 hours did not yield the compressive strengths approaching that of the silica fume mortars. The report includes tables and figures that detail the results of the study.

Technical Report Author: Nabil Bouzoubaa, V.M. Malhotra, CANMET Energy Technology Centre, Natural Resources Canada,