Abstract
The feasibility of the crack closure of cementitious composites reinforced with shape memory alloy (SMA) fibers was investigated by performing single-fiber pullout tests. To demonstrate the fast crack closing ability, in this study, a heat treatment (300 °C) was applied for a short time (10 min). A short heat treatment was applied for 10 min, after the slip reached 0.5 mm, to activate the shape memory effects of cold-drawn SMA fibers. Two types of alloys were investigated, NiTi and NiTiNb, with two geometries, either smooth or dog-bone-shaped. During the heat treatment, the pullout stress of the SMA fibers initially decreased due to thermal extension, and then increased after heating for 1–3 min, resulting from the shape memory effects. However, their pullout stress recovery during and after the heat treatment was different for the different alloys and fiber geometries. The NiTi fibers generally produced a higher and faster recovery in terms of their pullout stress than the NiTiNb fibers, while the dog-bone-shaped fibers showed a faster pullout stress recovery than the smooth fibers.
Highlights
Considerable research has been performed on extending the service life of civil infrastructures through the prevention of early concrete deterioration
The aforementioned high-performance construction materials cannot be applied for urgent repairs, even though they have shown a superior prevention of early concrete deterioration
Due to the issues noted above, the authors of this study propose the development of short shape memory alloy (SMA) fiber-reinforced cement composites with a fast crack closing capacity
Summary
Considerable research has been performed on extending the service life of civil infrastructures through the prevention of early concrete deterioration. Even the high-performance construction materials are unable to close existing concrete cracks in a short time for a quick (or instantaneous) repair of concrete infrastructure. Both the UHPCs and HPFRCCs have been shown to produce a significantly high tensile strength and cracking control capacity by generating multiple microcracks during tensile strain hardening [1,7], as well as a larger redistribution capacity of stresses [8], they remain unable to close existing cracks. The aforementioned high-performance construction materials cannot be applied for urgent repairs, even though they have shown a superior prevention of early concrete deterioration
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