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    Frost resistance of layered concrete systems incorporating ECC as overlay materials
    (Techno-Press, 2021) Yucel, Hasan E.
    Concrete structures are subjected to severe durability issues and freeze-thaw action is one of these detrimental issues. In this paper, the behavior of high-volume Class-F fly ash (FA) and slag (SL) incorporated Engineered Cementitious Composites (ECC) as overlay materials was assessed when they were under cyclic freezing and thawing effect. Silica fume concrete (SFC) was also tested as a control mixture which is generally used for overlaying purposes. Layered ECC/substrate concrete (SC) and SFC/SC beam specimens were produced and subjected to 300 freeze-thaw cycles in accordance with ASTM C666, Procedure A. Laboratory tests performed using the layered specimens were based on the determination changes of (i) residual mechanical properties (flexural strength -mid-span beam deflection curves), (ii) ultrasonic pulse velocity (UPV), (iii) mass loss, (iv) relative dynamic modulus of elasticity (RDME) and (v) durability factor (DF). Test results show that all layered specimens produced with different ECC mixtures safely survived 300 freeze-thaw cycles without any disturbance between the ECC overlay and SC interface. On the other hand, one out of six tested SFC/SC layered specimens survived 300 freeze-thaw cycles and final failure for five failed specimens took place from the interfacial planes Significantly better frost resistance of overlaid systems produced with ECCs than those with SFC was also verified with all of the tests proposed. Between different ECC mixtures, those produced with slag performed better than that those with Class-F fly ash.
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    Investigation of the Bond between Concrete Substrate and ECC Overlays
    (ASCE-AMER SOC CIVIL ENGINEERS, 2014) Sahmaran, Mustafa; Yucel, Hasan E.; Yildirim, Gurkan; Al-Emam, Muhannad; Lachemi, Mohamed
    Rigid concrete overlays have been used for smoothing damaged surfaces and/or restoring or improving the mechanical capacity of bridge decks for many years. However, engineered cementitious composites (ECCs), which demonstrate superior ductility with high strength and improved durability characteristics, are an attractive alternative to conventional overlay materials if a strong mechanical bond is formed between the overlay and the substrate material. An experimental study was performed to evaluate the bond strength between ECC overlay and an ordinary concrete substrate with smooth and rough surface textures. Microsilica concrete (MSC), generally used as an overlay material, was also prepared as a control mixture. ECC and MSC overlay mixtures were cast over the concrete substrate to determine bonding performance. Slant shear and splitting prism tests were performed with MSC and two ECC mixtures. The experimental results show that when ECC is used as an overlay material, bond strength is significantly increased compared to MSC. Under compression loading (slant shear test), the bond-strength properties of layered ECC substrate concrete cylinder specimens were greater than the strength of substrate concrete with compressive strength of around 30MPa. However, in the case of layered MSC substrate concrete cylinder specimen, failure consistently occurred at the interface.