Study on Surface Permeability of Concrete under Immersion

Liu, Jun; Xing, Feng; Dong, Biqin; Pan, Dong

doi:10.3390/ma7020876

Cited by 31 publications

(14 citation statements)

References 23 publications

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“…On the one hand, more hydrates bind more chloride ions; on the other hand, lower porosity means less pore solution carrying chloride ions, thus cement hydration may lower down the surface chloride concentration, as measured by the method used in this study. Leaching, which makes higher surface porosity and higher pore network connectivity [ 17 , 22 ], can undoubtedly bring on higher surface chloride concentration. It is the competition of these mechanisms which results in the overall trends as shown in Figure 2 .…”

Section: Resultsmentioning

confidence: 99%

Surface Chloride Concentration of Concrete under Shallow Immersion Conditions

et al. 2014

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Deposition of chloride ions in the surface layer of concrete is investigated in this study. In real concrete structure, chloride ions from the service environment can penetrate into concrete and deposit in the surface layer, to form the boundary condition for further diffusion towards the interior. The deposit amount of chloride ions in the surface layer is normally a function of time, rather than a constant. In the experimental investigation, concrete specimens with different mix proportions are immersed in NaCl solution with a mass concentration of 5%, to simulate the shallow immersion condition in sea water, and the surface chloride concentrations are measured at different ages. It is found that the surface chloride concentration increases following the increasing immersion durations, and varies from a weight percentage of 0.161%–0.781% in concretes with different mix proportions. The w/c (water-to-cement ratio) influences the surface chloride concentration significantly, and the higher the w/c is, the higher the surface chloride concentration will be, at the same age. However, following the prolonging of immersion duration, the difference in surface chloride concentration induced by w/c becomes smaller and smaller. The incorporation of fly ash leads to higher surface chloride concentration. The phenomena are explained based on pore structure analyses.

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Section: Resultsmentioning

confidence: 99%

Surface Chloride Concentration of Concrete under Shallow Immersion Conditions

et al. 2014

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“…Based on the results from 5 to 15 min, the volumes of water flow were plotted against square root of time. More details of this method can be found in previous publications [ 44 , 45 ]. The unit of the permeability index is normally 10 −7 m 3 /min 0.5 , and three parallel samples were tested and averaged to get one surface permeability index.…”

Section: Methodsmentioning

confidence: 99%

Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

et al. 2014

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This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP) test and the scanning electron microscopy (SEM) images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days.

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“…The described observations are fairly typical of concrete elements remaining permanently underwater. This may be caused by lowered permeability of the concrete cover after a certain time spent underwater [21] as well as by limited underwater contact with oxygen, carbon dioxide and other harmful elements or chemical compounds. The technical state of all the reinforced concrete elements of the part above the water was much worse: the surface layer of their concrete was destroyed to a large extent; in certain spots, deeper concrete layers were destroyed as well (Figs.…”

Section: Reinforced Concrete Structurementioning

confidence: 99%

TECHNICAL CONDITIONS OF THE UNIQUE STRUCTURE OF INVERTED SIPHON – HISTORY & PRESENT

Hulimka¹,

Kałuża

2019

Architecture, Civil Engineering, Environment

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An inverted siphon is sometimes used to enable a watercourse to pass under an obstacle. Such solution is usually applied for irrigation and sewage canals, but it is rarely observed in the case of rivers. There are two such passages in Poland the bigger one is the Klodnica River siphon under the Gliwice Canal, commissioned in 1936. The first part of the paper presents the history of the Gliwice Canal and, simultaneously, of the Klodnica River siphon. The further part describes the structure of the siphon and its usage assumptions as well as the technical condition of the construction after nearly 80 years of operation, including inspection results concerning the underwater parts. The description is supplemented with results of chemical examinations. Basic repair recommendations are also provided.

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Study on Surface Permeability of Concrete under Immersion

Cited by 31 publications

References 23 publications

Surface Chloride Concentration of Concrete under Shallow Immersion Conditions

Surface Chloride Concentration of Concrete under Shallow Immersion Conditions

Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

TECHNICAL CONDITIONS OF THE UNIQUE STRUCTURE OF INVERTED SIPHON – HISTORY & PRESENT

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