This paper presents the results of an investigation on the influence of a replacement of limestone powder (LSP) by silica sand (SS) on properties of engineered cementitious composites (ECC). For this purpose, five different ECC mixtures were adopted: ECC mixture with only SS (M1) for control purposes and four ECC mixtures in which SS is partially replaced by four levels of replacements (25, 50, 75 and 100% by weight of total SS) of LSP. The mechanical properties of ECC were investigated for 3, 28 and 90 days, while the durability tests were performed for 90 days. It was concluded that increase in LSP content resulted in a decrease in fluidity of ECC mixtures indicating longer flow times. Increase in the LSP content had a positive effect on the performance of the compressive strength, fracture toughness and flexural strength at the ages of 3 and 28 days, while this was not valid at the age of 90 days when compared to the reference mixture M1. Moreover, it can be said that the use of LSP instead of SS in ECC mixtures had the positive effect on ductility and good dispersion of fibres due to its fine particle structure compared to SS. On the other hand, the mass loss due to acid attack and the sorptivity coefficient of ECC specimens decreased, while the carbonation resistance increased in all ECC mixes compared to the reference mixture M1 with only SS when LSP content in ECC mixtures increased.

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.