Permeability to gas of partially saturated concrete

Jacobs, Frank

doi:10.1680/macr.1998.50.2.115

Cited by 45 publications

(24 citation statements)

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“…Moreover, the gas flow through the pore network is significantly influenced by the water saturation degree of the pores (Abbas et al, 1999;Jacobs, 1998). In this study, all samples were evacuated for 1 h. After the sample was evacuated for 1 h, the crack was dried while the pore network was still filled with pore solution, which blocks the pathway for the air flow.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Self-healing of cracks in cement paste affected by additional Ca²⁺ ions in the healing agent

Huang

2014

Journal of Intelligent Material Systems and Structures

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Cracks in reinforced concrete provide preferential access for aggressive substances into the concrete. Therefore, the corrosion of reinforcement bars is accelerated. Besides, carbonation, sulfate attack, and alkali-silicate reaction take place deep inside the concrete. Fortunately, from previous experiments, it was found that cracks in concrete can be healed with water and Ca is a main chemical element of the reaction products of self-healing. However, the ion concentrations in water can be various depending on the sources of water. There is still a lack of information on the effect of ion concentrations on selfhealing. In this article, the effect of Ca 2+ ions on self-healing was investigated experimentally. Ca(OH) 2 was added into water as a healing agent. Self-healing behavior of cracks with saturated Ca(OH) 2 solution was explored and compared with that with distilled water. In order to gain deeper insight into the mechanism, the reaction products of self-healing were characterized by energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. In addition, the filling fraction of cracks as a function of time was determined by means of backscattered electron image analysis. The efficiency of self-healing induced by saturated Ca(OH) 2 solution was evaluated and compared with that with distilled water.

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Section: Experimental Techniquesmentioning

confidence: 99%

Self-healing of cracks in cement paste affected by additional Ca²⁺ ions in the healing agent

Huang

2014

Journal of Intelligent Material Systems and Structures

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“…This result, clearly identified for CEM I pastes, is in agreement with a recent study performed by Jacobs. 13 For higher water saturations, the discrimination is more difficult to establish. On the other hand, it should be noted that gas permeability values corresponding to a water saturation close to zero were measured in specimens dried in an oven at 608C for more than two months.…”

Section: Resultsmentioning

confidence: 99%

Gas permeability of unsaturated cement-based materials: application of a multi-scale network model

Gallé

Daïan

2000

Magazine of Concrete Research

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A multi-scale network model based on the percolation theory and using a renormalization method was applied to describe the porous space of cement-based materials and to determine their gas transport properties. Gas permeability was measured on hardened cement pastes prepared with French OPC (CEM I) and BFS±PFA (CEM V) cements currently used in the nuclear waste industry. These experiments were carried out to study the influence of the degree of water saturation and of the microstructure on materials gas transport properties. Between 10 and 100% relative humidity, the cement pastes' average gas permeability varies over five orders of magnitude (10 À16 ±10 À21 m 2 ). Results show that in the range of water saturation considered, there is no linear relationship between the gas permeability and the degree of water saturation in percentage terms. Permeability change was well observed for cement pastes characterized by w/c ratios of 0´30, 0´40 and 0´50, in the low water saturation domain (,60%). CEM V pastes are globally more permeable to gas than CEM I pastes in the range of one order of magnitude. For the modelling aspect, the application of the XDQ multi-scale model made it possible to model a porous network equivalent to the one obtained by the mercury intrusion porosimetry test. Each class of pores is associated with an elementary cubic random network. The whole porous system is rebuilt by a recurrent process involving superposition and rescaling of all the elementary networks. Then, an equivalent conductivity of the multiscale network is computed and extended to gas permeability. Modelling and experimental results are in agreement and show that mercury intrusion is a relevant method to characterize a porous space in order to estimate the gas permeability of cement-based materials with a conceptual model.

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“…For laboratory tests, it has been recommended therefore to cast the cavity instead of drilling [4]. This method is recommended therefore as a standard test method for gas permeability measurements.…”

Section: Evaluation Of Test Methods and Durability Characteristicsmentioning

confidence: 99%

Final Report

Perdrix¹

1999

Mat. Struct.

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Permeability to gas of partially saturated concrete

Cited by 45 publications

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Self-healing of cracks in cement paste affected by additional Ca²⁺ ions in the healing agent

Self-healing of cracks in cement paste affected by additional Ca²⁺ ions in the healing agent

Gas permeability of unsaturated cement-based materials: application of a multi-scale network model

Final Report

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Permeability to gas of partially saturated concrete

Cited by 45 publications

References 0 publications

Self-healing of cracks in cement paste affected by additional Ca2+ ions in the healing agent

Self-healing of cracks in cement paste affected by additional Ca2+ ions in the healing agent

Gas permeability of unsaturated cement-based materials: application of a multi-scale network model

Final Report

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Product

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Self-healing of cracks in cement paste affected by additional Ca²⁺ ions in the healing agent

Self-healing of cracks in cement paste affected by additional Ca²⁺ ions in the healing agent