Sulfate attack expansion mechanisms

Müllauer, W.; Beddoe, R.E.; Heinz, D.

doi:10.1016/j.cemconres.2013.07.005

Cited by 291 publications

(140 citation statements)

References 11 publications

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“…The behavior depicted in Fig. 14b, where pores from 8 nm to 30 nm contribute to the total strain, is in accordance with the phenomenon described by the crystallization pressure theory [29,35].…”

Section: -Validation Based On Experimental Results By Brownsupporting

confidence: 69%

“…This fact reflects the phenomenon described by the crystallization pressure theory, in which crystals growing in small pores (of order of tens of nanometers) are more likely to generate significant expansive pressure [29]. In a recent publication by Müllauer [35], it was quantified that the formation of ettringite in small pores (10 to 50 nm) generates a stress of about 8MPa that exceeds the tensile strength of the binder matrix and is responsible for damage. The same author suggests that bigger pores are not able to generate enough crystallization pressure to exceed the tensile strength of the matrix.…”

Section: -Validation Based On Experimental Results By Brownmentioning

confidence: 97%

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Alternative methodology to consider damage and expansions in external sulfate attack modeling

Ikumi

Cavalaro

Segura

et al. 2014

Cement and Concrete Research

147

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A diffusion -reaction numerical model is proposed to simulate the response of concrete exposed to external sulfate attack. Diffusion properties are modified based on the strain reached and the ratio of porosity filled by ettringite. A direct and intuitive approach is proposed for the consideration of the diffusion in a cracked porous media based on the constitutive law of the material. A methodology to compute expansions based on a more realistic consideration of the concrete porosimetry is presented, by which it is possible to distinguish different strain contributions from different pore sizes. The described approach also allows the consideration of different capacities to accommodate expansive product for each pore size considered and the faster filling rate existent in small pores. Critical parameters of the numerical model developed are recognized and

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Section: -Validation Based On Experimental Results By Brownsupporting

confidence: 69%

Section: -Validation Based On Experimental Results By Brownmentioning

confidence: 97%

Alternative methodology to consider damage and expansions in external sulfate attack modeling

Ikumi

Cavalaro

Segura

et al. 2014

Cement and Concrete Research

147

View full text Add to dashboard Cite

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“…In the process of external sulphate attack, the sulphate ions from an external source (in this case AMD) penetrate into concrete. These ions then react with free and abundantly available portlandite in the ground mass of concrete, forming gypsum, which in turn reacts with monosulphate to form ettringite ( (ettringite) Hence, in a cementitious system subject to sulphate attack, ettringite is the predominant reaction product (perhaps with some presence of gypsum), generating expansive pressures reported to be in the range of 8 MPa, depending on the sulphate concentration (Müllauer et al 2013). These high pressure levels by far exceed the tensile strength of concrete, which can be as low as 2 MPa (Kong & Evans 1980).…”

Section: Sulphate Attack In Concretementioning

confidence: 99%

Disintegration of concrete construction induced by acid mine drainage attack

Ekolu

Diop²,

Azene

et al. 2016

J. S. Afr. Inst. Civ. Eng.

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This paper presents findings from microanalytical investigation conducted on disintegrated concrete that had been used to construct a weir within a coal mine in South Africa. The concrete was in contact with polluted mine water, commonly referred to as acid mine drainage (AMD). Accordingly, the weir had been exposed to AMD decant which led to disintegration of concrete due to chemical attack. Investigations were conducted by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD). The field samples examined consisted of soft, broken concrete chunks and a whitish powdery substance that had crystallised and formed a surface coating on certain cracked locations on the deteriorated concrete. No evidence of pyrite oxidation was found in the investigation. The observed deterioration is discussed in relation to acid attack mechanism and its possible co-existence with external sulphate attack process.

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“…After 90 days in saturated limewater, the thin-walled hollow cylinders were cut and polished at both ends to be horizontal with the length of 70 mm (outer diameter 30 mm, inner diameter 25 mm, wall thickness 2.5 mm) [2]. Then three types of longitudinal restraints were applied on the samples with a spring, a thin steel bar (diameter 3 mm for the middle part) and a thick steel bar (diameter 7 mm for the middle part) in the middle (Figure 1) to build the non-restraint, low-restraint and highrestraint conditions.…”

Section: Materials and Testing Proceduresmentioning

confidence: 99%

“…Several theories have been proposed to explain the possible mechanism of expansion, such as topochemical reactions, volume increase, swelling and crystallization pressure. Although the mechanism is still under debate, the crystallization pressure theory has become the most widely cited hypothesis in recent years [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on Cement Paste Degradation Under External Sulfate Attack

Çopuroğlu

Schlangen

et al. 2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

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External sulfate attack is one of the situations that may cause gradual but severe damage in cementitious materials, which may lead to cracking, increased permeability and strength loss. In this paper, thin-walled hollow cement paste cylinders with a wall thickness of 2.5mm were made considering the slow penetration process of sulfate ions under continuous immersion condition. Three types of longitudinal restraints were applied on the hollow cement paste cylinders by means of a spring and steel bars through the specimens in order to facilitate non-, low-and high-restraint conditions. Strain gauges were glued on the steel bars so as to increase the accuracy of the measurements. During the immersion tests, specimen expansion and generated stress were monitored. Additionally, sulfur element mapping was generated by EDS (energy dispersive X-ray spectrometry).Expansion behaviours of the hollow cement paste cylinders were simulated under the aforementioned restraint conditions which were carried out based on the Delft lattice fracture model. The expansion was assumed to be realized upon formation of ettringite inside the nanopores of the cement hydration products. Local expansion stresses were computed by employing the crystallization pressure theory. A comparison between the simulation and the experimental results showed reasonable correlation and tendency for further exploration of our approach.

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Sulfate attack expansion mechanisms

Cited by 291 publications

References 11 publications

Alternative methodology to consider damage and expansions in external sulfate attack modeling

Alternative methodology to consider damage and expansions in external sulfate attack modeling

Disintegration of concrete construction induced by acid mine drainage attack

Experimental and Numerical Study on Cement Paste Degradation Under External Sulfate Attack

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