Compressive and Flexural Strength of High-Volume Fly Ash Mortars Aged with Air-entraining Admixtures

¹ Civil Engineering Department, University of Kirkuk, Kirkuk, Iraq
² School Buildings Department, Ministry of Education, Kirkuk, Iraq

^a* Corresponding author mohammed.k.ali@uokirkuk.edu.iq
^b qaiscivil1982@gmail.com
^c shahinahmad@uokirkuk.edu.iq
^d imanali_78@uokirkuk.edu.iq
^e moayadmk@uokirkuk.edu.iq

Abstract

This paper presents the findings of an investigation into the compressive and flexural strength of various cement mortars containing very high levels of Class F fly ash (HVFA). A total of twelve cement mortar mixtures with constant water/powder ratios, cement, sand, and Air-Entraining Admixtures (AEA) were subjected to 20, 30, 40, 50, 60, and 70% partial replacement of cement content with Fly Ash (HVFA) class F. The results of the tests show that the compressive and flexural strength decreased slowly as the fly ash content increased to up to 40%, but the strength values began to decrease dramatically with the addition of a higher amount of fly ash. According to the results, the best percentage of cement replacement with fly ash in mortar is 40%. It has 24% less compressive strength and 13% less flexural strength than 20% FA mortar. In general, the air-entraining admixture has no negative effect on the properties of the cement mortars. The measured properties of the hardened mortar are very satisfying.