Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

Choi, Eunsoo; Kim, Dong-Joo; Youn, Heejung; Nam, Tae-Hyun

doi:10.1088/0964-1726/24/12/125010

Cited by 32 publications

(11 citation statements)

References 18 publications

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“…The SMA fibers are studied in recent decades because of the superior properties of the shape memory effect and superelasticity. The recovery stress due to the shape memory effect was the cause of crack-closing [ 13 , 14 , 15 ], prestressing [ 16 , 17 ], and crack-repairing [ 18 ] in the cementitious composite. The superelastic characteristic provides the self-recovering capacity under the unloading condition [ 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Straining Behavior of Mortar Reinforced by Cold Drawn Crimped and Dog-Bone-Shaped Fibers under Monotonic and Cyclic Compressions

2021

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The straining behavior of the shape memory alloy (SMA) fibers-reinforced mortar was investigated in this study by the monotonic compressive and cyclic compressive tests. Two types of SMA fibers with a crimped and dog-bone shape were used due to the high pullout resistance capacity, which guaranteed that the fibers and mortar matrix were composited well. The plain mortar was mixed with two different compositions to create the higher elastic modulus mortar matrix and the lower elastic modulus mortar matrix compared with the elastic modulus of SMA fibers. The results of the experimental test indicated that the non-heated SMA fibers could control the strains in both elastic and plastic phases; in which, the crimped fiber was more effective in precracking due to the higher composite capacity while the dog-bone-shaped fiber had a higher effect in post-cracking. After heating, the dog-bone-shaped fiber slipped more than that of the crimped fiber; thus, the heated crimped fiber was more effective than the heated dog-bone-shaped fiber in controlling strains after cracking. The effect of SMA fibers on the elastic modulus depended on both the elastic modulus of mortar matrix and the property of SMA fibers. In the plastic phase, the fibers were effective on reducing the speed of damage in monotonic case. An equation using reinforcing index was suggested for damage evolution in the cyclic case.

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Section: Introductionmentioning

confidence: 99%

Straining Behavior of Mortar Reinforced by Cold Drawn Crimped and Dog-Bone-Shaped Fibers under Monotonic and Cyclic Compressions

2021

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“…Shape memory alloy (SMA) materials were invented some decades ago, and SMA fibers have recently been researched as reinforcements to cementitious materials. Because of the unique properties of the shape memory effect and super-elasticity, SMA fibers have some advantages in crack-closing, pre-stressing, crack-repairing, and self-centering [ 19 , 20 ]. Many SMA fiber shapes, such as dog-boned-shaped, L-shaped, N-shaped, paddle-shaped, and crimped, have been introduced [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Behaviors of Mortar Reinforced with NiTi SMA Fibers under Impact Compressive Loading

Choi

Seo

2021

Materials

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In this study, a compressive impact test was conducted using the split Hopkinson pressure bar (SHPB) method to investigate SMA fiber-reinforced mortar’s impact behavior. A 1.5% fiber volume of crimped fibers and dog-bone-shaped fibers was used, and half of the specimens were heated to induce recovery stress. The results showed that the appearance of SMA fibers, recovery stress, and composite capacity can increase strain rate. For mechanical properties, the SMA fibers reduced dynamic compressive strength and increased the peak strain. The specific energy absorption of the reinforced specimens slightly increased due to the addition of SMA fibers and the recovery stress; however, the effect was not significant. The composite behavior between SMA fibers and the mortar matrix, however, significantly influenced the dynamic compressive properties. The higher composite capacity of the SMA fibers produced lower dynamic compressive strength, higher peak strain, and higher specific energy absorption. The composite behavior of the dog-bone-shaped fiber was less than that of the crimped fiber and was reduced due to heating, while that of the crimped fiber was not. The mechanical properties of the impacted specimen followed a linear function of strain rate ranging from 10 to 17 s−1; at the higher strain rates of about 49–67 s−1, the linear functions disappeared. The elastic modulus of the specimen was independent of the strain rate, but it was dependent on the correlation between the elastic moduli of the SMA fibers and the mortar matrix.

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“…Freed and Aboudi (2008) investigated the shape memory performance of SMA in the composite and found that the presence of SMA fibres in concrete significantly affect ductile performance of concrete in the case of transverse loading and the residual plastic strain decreased with the increase of activation temperature. Choi et al (2015Choi et al ( , 2017 concluded that the addition of SMA fibre in concrete improved the flexural strength and the crack-closing capacity of concrete. Sherif et al (2017) validated that crack recovery ratio was increased after adding SMA fibre, to 65% and 68% at 0.5% and 1.0% fibre volume ratios.…”

Section: Introductionmentioning

confidence: 99%

Flexural and toughness properties of NiTi shape memory alloy, polypropylene and steel fibres in self-compacting concrete

Aslani

Liu

Wang

2019

Journal of Intelligent Material Systems and Structures

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Self-compacting concrete presents good workability to fill complicated forms without mechanical vibrations. This concrete is often reinforced with fibres to improve the strength and toughness. This study investigated the use of nickel -titanium (NiTi) shape memory alloy fibres in comparison with polypropylene and steel fibres in self-compacting concrete. The performances of the fresh fibre–reinforced self-compacting concrete are explored by slump flow and J-ring experiments. Meanwhile, the static and cyclic flexural tests are conducted to estimate the bending resistance strength performance, residual deformation and recovering capacity of shape memory alloy, polypropylene and steel fibre–reinforced self-compacting concrete. Moreover, the flexural toughness of the shape memory alloy, polypropylene and steel fibre–reinforced self-compacting concrete is calculated using four different codes. The shape memory alloy fibre–reinforced self-compacting concrete with 0.75% volume fraction presents the largest flexural strength, re-centering ability and toughness in comparison with polypropylene and steel fibre–reinforced self-compacting concretes. The experimental results demonstrated the beneficial influence of the shape memory and superelastic properties of NiTi in postponing initial crack formation and restricting the crack widths.

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Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

Cited by 32 publications

References 18 publications

Straining Behavior of Mortar Reinforced by Cold Drawn Crimped and Dog-Bone-Shaped Fibers under Monotonic and Cyclic Compressions

Straining Behavior of Mortar Reinforced by Cold Drawn Crimped and Dog-Bone-Shaped Fibers under Monotonic and Cyclic Compressions

Dynamic Behaviors of Mortar Reinforced with NiTi SMA Fibers under Impact Compressive Loading

Flexural and toughness properties of NiTi shape memory alloy, polypropylene and steel fibres in self-compacting concrete

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