Rapid Degradation of Concrete Anchorage Performance by Liquid Water

Chijiwa, Nobuhiro; Hong, Thi Mai; Iwanami, Mitsuyasu; Saito, Tomohisa; Yamaya, Atsushi; Motegi, Hiroyuki; Shinozaki, Hiroo

doi:10.3151/jact.13.438

Cited by 9 publications

(5 citation statements)

References 6 publications

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“…This phenomenon has also been observed in wheel running tests for RC slabs where water is supplied to the upper surface [1]. Correspondingly, during the cyclic pull-out test of anchor frames, the pumping out of sludge from anchorage concrete was visible when water was supplied to the specimen [2]. In addition, the degradation of the rough cracked surface under the cyclic shear was clear when water was supplied to concrete specimens [3].…”

Section: Introductionsupporting

confidence: 52%

“…For a further understanding of the phenomena, a multiple regression analysis for both the positive and negative water pressures was performed. = 0.0023 × ( ) − 0.0365 × ( ) + 0.1931 (2) where F is the weight of the fine aggregates, j(p) and j(n) are the degradation indices, focusing on the positive and negative water pressures, respectively. The coefficient of positive pressure (0.0023) was smaller than that of negative pressure (0.0365).…”

Section: Discussionmentioning

confidence: 99%

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Degradation of submerged/wet concrete under cyclic compression and cyclic shear

2019

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The aim of this study is to identify a specific degradation of concrete that has been observed in bridge decks made of reinforced concrete (RC). To control the phenomenon, fundamental studies were conducted. Compressive loads and external water pressure were cyclically applied to submerged concrete cylinder specimens with different pre-loading and restraint conditions. The turbidity of the water in the tank was generally observed during the loading, and the pH of the turbid water steadily increased as the number of cycles increased. Thereafter, fine aggregates without a cement matrix were found on the inner surfaces of split specimens. These phenomena were quantitatively analyzed, and the analyses suggested that cyclic water pressure acted on the inside of pre-cracked specimens and washed out their cement matrix. The degradation of a rough cracked surface was also examined using the cyclic shear test, with/without a water supply to the crack. The shear slip and the orthogonal displacement were clearly amplified with an increase in the number of cycles when the water supply was present. The mechanical properties of cracked concrete with water in shear was discussed in accordance with that of liquefaction. These fundamental studies could help to determine the acceleration factors of the degradation and provide certain thresholds for practical use.

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Section: Introductionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Degradation of submerged/wet concrete under cyclic compression and cyclic shear

2019

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“…Although the authors have found no research into the effect of high water pressure on reinforcement bonding under static and cyclic conditions, they attributed that it influences the deterioration of the anchorage at the matrix/rebar interface. On the other hand, there have been a few studies on the fatigue response of reinforced concrete in the presence of water, which focused on the bond strength of deformed steel bars [ 36 , 37 , 38 , 39 ]. It was concluded that repeated reverse-cyclic loading led to pulverization of the concrete in the vicinity of the deformed steel bar, turning it into sludge and leading to pullout failure.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Effect of Repeated High Water Pressure on the Compressive and Bond Strength of Concrete with/without Steel Bar

2021

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The application of reinforced concrete for permanent and temporary deep ocean structures has recently become more prevalent; however, the static and dynamic effects of high water pressure on concrete remain unexplored. This paper investigates the influence of high water pressure (60 MPa) on four series of concrete cylinders with and without an embedded steel bar under sustained and cyclic loading conditions. The residual compressive strength, bond strength, and associated evolution of surface and internal damage are evaluated after exposing concrete cylinders to a water pressure of 60 MPa. The first series is exposed to sustained water pressure for 7 and 60 days, while the other series is tested under repeated water pressure for 10, 20, 30, 60, and 150 cycles. The results reveal that residual compressive strength falls immediately by 16% within 7 days of sustained high water pressure, but the strength then remains stable up to 60 days. Under repeated high water pressure, residual compressive strength gradually reduces by up to 40% until 60 cycles, after which it remains reasonably stable until 150 cycles as crack propagation is arrested at a certain depth within the concrete cylinders. The bond strength between the steel bar and matrix is observed to decrease considerably under repeated cycles of 60 MPa water pressure up to 26%. The damage gradually propagates at the matrix/steel bar interface under the repeated water pressure, resulting in a reduction in residual pullout capacity.

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“…In particular, the structures supporting wind turbines, especially the foundation made of concrete, have been paid attentions in recent years. There are the reports that investigate cracks on foundation concrete [4][5][6][7]. It is not easy to identify the cause of cracks, while repeated action transferred from the tower is thought to be one of the causes.…”

Section: Introductionmentioning

confidence: 99%

“…It is not easy to identify the cause of cracks, while repeated action transferred from the tower is thought to be one of the causes. Therefore, fatigue of supporting structure made of concrete has become a main concern of researchers [7][8][9][10]. Even though the cracks are not always the trigger of structural collapse of wind turbine, further investigations are required for safe and steady operation of power plant.…”

Section: Introductionmentioning

confidence: 99%

Evaluation and Stability Analysis of Onshore Wind Turbine Supporting Structures

Fujiyama¹,

Koda²,

Sento³

2018

Stability Control and Reliable Performance of Wind Turbines

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This chapter shows research of stability of supporting structure of onshore wind turbine foundations based on field measurements, finite element (FE) analysis and laboratory experiment. In order to investigate the relation of action-response of tower-foundation system, long-term field measurements were carried out for two existing onshore wind turbines with/without piles for its foundations. Then, the models were built up for three-dimensional nonlinear FE analyses. The damage processes of reaching failure were examined by FE models, and limit state of foundations was individually defined by fatigue limit state of concrete. Consequently, the stress-number of cycle (S-N) diagram derived from both experiment and analysis was discussed for the assessment of existing structure.

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Rapid Degradation of Concrete Anchorage Performance by Liquid Water

Cited by 9 publications

References 6 publications

Degradation of submerged/wet concrete under cyclic compression and cyclic shear

Degradation of submerged/wet concrete under cyclic compression and cyclic shear

Investigating the Effect of Repeated High Water Pressure on the Compressive and Bond Strength of Concrete with/without Steel Bar

Evaluation and Stability Analysis of Onshore Wind Turbine Supporting Structures

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