Bond behavior between steel bars and carbon nanotube modified concrete

Bonding of Steel Bars in Concrete with the Addition of Carbon Nanotubes: A Systematic Review of the Literature

“…Song et al [39] studied the effect of different CNT contents, concrete cover (c), and bar diameter (d) in the steel-concrete bond, performing beam tests. The results indicated increases of 37.2% and 49.7% in the maximum bond strength when using CNT contents equal to 0.10% and 0.15% by weight of cement, respectively.…”

“…Considering the seven selected articles, six (86%) performed bond tests of steel bars in some type of concrete, with three (43%) using a conventional concrete with a compressive strength of 50 MPa [34,38,40], two (29%) also using a conventional concrete but with a compressive strength of 30 MPa [35,39], and one (14%) using an ultra-high-performance concrete with a compressive strength higher than 150 MPa [37], and all of these strengths were measured at 28 days. In this context, Hawreen et al [34] state that the addition of CNTs to cementitious matrices is generally used in mortars or cement paste because of the difficulty of dispersing them in a mixture with coarse aggregates and mainly in large quantities.…”

“…Regarding the bond test performed, six articles (86%) performed the pull-out test and only one (14%) opted for the beam test. This is because, although the beam test represents reliably the steel-concrete bond behavior under tension [39], it is very laborious [59], while the pull-out test is simpler and easier to execute [60], provides accurate results [61], and shows clearly the influence of each variable on the test results [62]. Moreover, different setups and standards were used in the tests, considering the load or displacement applied to the specimen, the machine used, the geometry, the dimensions, and the specimen number, which reflect the lack of standards in the study of steel-concrete bonding.…”

“…Moreover, different setups and standards were used in the tests, considering the load or displacement applied to the specimen, the machine used, the geometry, the dimensions, and the specimen number, which reflect the lack of standards in the study of steel-concrete bonding. Song et al [39] were the only authors who performed the beam flexural test, following the RILEM-CEB RC5 [24] and the Chinese GB/T 50,152 [63] standards. To the best of the authors' knowledge, the specimen dimensions' influence on this specific test has not yet been investigated.…”

Nano-modification in digital manufacturing of cementitious composites

“…Similarly, researchers also found modest improvement in residual mechanical properties after high-temperature exposure and overall higher maximum temperature before failure (Afzal & Khushnood, 2021). For the improvement of bond with reinforcement, CNTs are found to be more effective than nano-silica, with an increase up to 50% (Song et al, 2020).…”