EARLY-STRENGTH DEVELOPMENT OF PORTLAND-CEMENT MORTARS CONTAINING AIR CLASSIFIED FLY ASHES

A study of the effect of different fly ash sized fractions on compress ive and flexural strength of blended cement mortar is presented. Morta rs containing fly ashes, replacing 15 to 60% of Portland cement, were prepared, and compressive and flexural strengths compared with ''only cement'' mortar. The influence of curing temperature was also studied. The study reveals that: a) compressive and flexural strength for mort ars containing fly ash (or their sized fractions) are significantly en hanced when curing temperature is raised; b) the content of fly ash fi nest particles (less than 10 mu m) is a crucial parameter for yielding a compressive strength enhancement; c) Good correlations between stre ngths and particle mean diameters were observed when fly ash percentag e of substitution was 60%.