Investigation of Falling on Concrete Fragments From Rc Structures

Ishibashi, Toshiyuki; Furuya, Tokiharu; Hamazaki, Naoyuki; Suzuki, Hiroto

doi:10.2208/jscej.2002.711_125

Cited by 11 publications

(6 citation statements)

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“…Figure 7 shows the relationship between carbonation depth, cover depth, and spalling, according to the apparent corrosion level [22], which was replotted by the authors focusing on water supply. In the survey, the members with a cover depth of more than 40 mm had little spalling and slight corrosion, regardless of the carbonation depth, water supply and construction year, similar to the results of the survey by Ishibashi et al [10]. The above surveys also suggested that an adequate cover depth of over 40 mm can prevent spalling by corrosion, even though porous cover concrete with a low strength of less than 15 MPa or a high water-to-cement ratio (W/C) of over 55% was included in the surveyed structures.…”

Section: Relationship Among Cover Depth Carbonation Depth and Spallin...supporting

confidence: 86%

“…Most of the structures were located far from the seashore. Figure 6, which is reproduced by the authors based on [10], shows the relationship between spalling, carbonation depth, and cover depth with and without water supplied by rainfall or other means. Spalling due to corrosion is mostly prevented when the cover depth is more than 30 mm regardless of the carbonation depth and age, even in the presence of water.…”

Section: Relationship Among Cover Depth Carbonation Depth and Spallin...mentioning

confidence: 97%

“…Similar surveys focusing on water supply and carbonation depth were reported in Japan. Ishibashi et al [10] measured the cover depth and carbonation by drilling the cover concrete depth in 95 railway structures (mainly viaducts) with service lives ranging 15-80 years. Most of the structures were located far from the seashore.…”

Section: Relationship Among Cover Depth Carbonation Depth and Spallin...mentioning

confidence: 99%

“…For real structures in the field, it has been reported that corrosion was unlikely to be observed when the concrete was directly kept from moisture exposure, even when carbonation reached the reinforcing steel; however, corrosion can occur because of rainfall moisture and other sources [8,9]. Ishibashi et al [10] and Maehara and Iyoda [11] reported that moisture supply is more likely to cause spalling in reinforced concrete. In Japan, the effect of water penetration on corrosion has been considered [12,13], along with carbonation assessment in the design specifications to utilise blended cement, reported to have a higher carbonation rate than concrete without mineral admixtures [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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The Cover Depth Effect on Corrosion-Induced Deterioration of Reinforced Concrete Focusing on Water Penetration: Field Survey and Laboratory Study

et al. 2021

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Reinforced concrete bridges were visually surveyed in Japan, Thailand, and Vietnam to study the deterioration caused by internal steel corrosion under different climates, focusing on the concrete cover depth. Spalling or cracking arising from corrosion is likely where water is supplied. According to prior studies and our surveys, a concrete cover depth of more than 40 mm was found to prevent spalling, regardless of environmental conditions and structure age. Because water supply at steel is a key corrosion factor, it was hypothesised that under natural conditions, the water penetration in concrete would remain at a depth of approximately 40 mm. Our laboratory study examined water penetration under drying and wetting conditions. The results also suggested that under periodic rainfall conditions, the threshold of water penetration was not exceeded. The numerical study indicated maximum moisture evaporation to facilitate oxygen diffusion occurred at a depth of approximately 30–40 mm unless the concrete was exposed to continuous drying for more than one month. It was experimentally and numerically concluded that an adequate cover depth of greater than 40 mm could inhibit moisture and oxygen penetration at the steel, which supported the survey findings of cover depth effect on a high resistance to corrosion-induced deterioration despite an increase in service life.

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Section: Relationship Among Cover Depth Carbonation Depth and Spallin...supporting

confidence: 86%

Section: Relationship Among Cover Depth Carbonation Depth and Spallin...mentioning

confidence: 97%

Section: Relationship Among Cover Depth Carbonation Depth and Spallin...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Cover Depth Effect on Corrosion-Induced Deterioration of Reinforced Concrete Focusing on Water Penetration: Field Survey and Laboratory Study

et al. 2021

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“…It has been made clear that controlling water ingress from the surface of concrete structures will lead to improving the resistance of the structures against spalling of concrete due to steel corrosion (Ishibashi et al 2002), ASR, and deterioration due to chlorides. In 2005, JSCE published "Recommendation for concrete repair and surface protection of concrete structures" (JSCE 2005), and therefore, water repellents are expected to contribute to control of water ingress from the surface of structures (Medeiros et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Optimum Surface Protection System with Silane Type Water Repellents

Hosoda

Matsuda

Kobayashi

2010

ACT

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To establish an optimum surface protection system with silane type water repellents, experimental investigations were conducted for 2 kinds of water repellents that had shown good water absorption controlling effect in a previous exposure test in an actual structure carried out by the authors. The effects of the age of application of water repellents and the effects of the curing conditions before and after the application on the penetration depth of water repellents and the water absorption controlling effect were investigated for concretes of different mix proportions with four different W/C, of 35%, 42%, 50%, 65%. Furthermore, the specimens used for the water absorption tests were subjected to a weathering test to examine the durability of the water absorption controlling effect. In dry concrete, both water repellents showed a good water absorption controlling effect. While it is generally considered desirable that the water repellents be applied at an early age to obtain a better water absorption controlling effect, the authors propose that water repellents should be applied not too early for low W/C concrete, in order to ensure a penetration depth of at least 1 to 2 mm. The penetration depth and water absorption controlling effect are affected by the curing conditions before and after application of the water repellents. When the specimens with water repellents were subjected to a weathering test using a Xenon arc lamp for 98 days (equivalent to 2.8 years of weathering in Tokyo), no degradation of the water repellent layer was observed. Considering the experimental results in this study, an optimum surface protection system for newly constructed structures is proposed.

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Time-dependent seismic reliability of isolated bridges considering ageing deterioration of lead rubber bearings

Matsuzaki

2022

Structure and Infrastructure Engineering

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Investigation of Falling on Concrete Fragments From Rc Structures

Cited by 11 publications

References 0 publications

The Cover Depth Effect on Corrosion-Induced Deterioration of Reinforced Concrete Focusing on Water Penetration: Field Survey and Laboratory Study

The Cover Depth Effect on Corrosion-Induced Deterioration of Reinforced Concrete Focusing on Water Penetration: Field Survey and Laboratory Study

Optimum Surface Protection System with Silane Type Water Repellents

Time-dependent seismic reliability of isolated bridges considering ageing deterioration of lead rubber bearings

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