This paper investigates the effect of different dosages of fly ash (FA) and silica fume (SF) in self-compacting mortars (SCMs) on the freeze-thaw (F-T) resistance as well as fresh and hardened properties. Nine mortar mixtures were prepared at $640\mathrm{kg}/{\mathrm{cm}}^3$ of unit weight and water/binder (w/b) ratio between 0.43 and 0.50. All SCMs contained either FA or SF, but the control mixture contained only portland cement. The fresh properties of SCMs were determined using viscosity, slump flow, and V-funnel flow time tests. The compressive strength of SCMs containing SF was generally found to be higher than that of SCMs with FA and the control mixture. At 28 and 91 days, the control mixture had the highest flexural tensile strength in all blends except SF20 at 91 days. In addition, with increasing replacement rates of FA and SF in SCMs, the sorptivity of SCMs with FA resulted in an increase, whereas a reduction in the sorptivity of SCMs with SF was observed. Finally, as replacement ratio of FA and SF increased, the relative dynamic elastic modulus of SCMs showed a reduction, and the decreases in the elastic modulus of SCMs containing SF occurred sharply compared with SCMs incorporating FA because of the deleterious effects of SF on F-T cycles. Moreover, as SF and FA content increased, the dynamic elastic modulus of SCMs decreased at 28 days.

In this paper, micro and macro steel fibres were used to understand the influences of blended fibre addition on the fresh and hardened properties of self-compacting concrete (SCC). Five mixtures containing micro and macro steel fibres were prepared in different combinations and in each mixture, the sum of the steel fibre content was kept constant as 1%. To measure the workability of fibre-reinforced self-compacting concrete (FR-SCC), slump-flow diameter, t₅₀₀ and J-ring tests were conducted. The results indicated that when the micro steel fibre ratio became more than 0.25%, the fresh properties of SCC were affected negatively. To determine the hardened properties of FR-SCC mixtures, compressive, splitting tensile and flexural tensile strength tests were performed and also ultrasonic pulse velocity (UPV) of the specimens was measured. The micro steel fibre inclusion had positive effect on compressive strength while it caused a reduction in splitting tensile and flexural tensile strength. With regard to the crack formation, in the mixtures having higher content of macro steel fibre, multiple crack behaviour was observed. Moreover, it was revealed from the results that the mixtures exhibited deflection-hardening response in the case of inclusion higher amount of macro steel fibre.