The formation and role of ettringite in Iowa highway concrete deterioration

Lee, Hyungjun; Cody, Robert D.; Cody, Anita M.; Spry, Paul G.

doi:10.1016/j.cemconres.2004.05.029

Cited by 95 publications

(42 citation statements)

References 39 publications

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“…Several previous works dealing with ettringite have focused on applications in the civil construction sector, since its formation directly influences the physical and chemical properties of both Portland cement and cements with sulfoaluminate matrices [20][21][22]. Recently, ettringite has also received special attention in the mining-metallurgical sector because its precipitation can be used to remove sulfate from effluents and mine waters [12][13][14][15][16][23][24][25], due to its low solubility in aqueous media (log Ksp (298 K) = 44.91 ± 1.06) [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…Despite the large number of studies that have investigated either the use of ettringite in waste water treatment [12-16, 23-25, 36, 37] or its effect on the physical and chemical behavior of various types of cement [10,11,22,26,[38][39][40][41], as well as works dedicated to the structural characterization of this material [4-9, 18, 20, 27-29, 42], only a few studies investigating the thermal decomposition of ettringite exist in the literature [21,[43][44][45]. Therefore, the first aim of the present work is to characterize the ettringite decomposition products by applying the techniques of X-ray diffraction (XRD), infrared (IR) spectroscopy, thermogravimetry (TG/DTA), and scanning electron microscopy (SEM).…”

Section: Introductionmentioning

confidence: 99%

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Kinetic and thermal decomposition of ettringite synthesized from aqueous solutions

Guimarães

Oliveira

Leão

2016

J Therm Anal Calorim

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The kinetics of the thermal decomposition of a synthetic ettringite sample was studied between 298 and 820 K in an inert atmosphere for the present work. The ettringite and its thermal decomposition products were characterized using X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Four endothermic events were observed with thermogravimetry curves, the maxima of which occurred at 366, 397, 537, and 641 K. All events were associated with the loss of water molecules with different degrees of interaction within the ettringite structure. Chemical equations for each decomposition step were proposed based on the percentages of mass loss observed. In addition, for the first time, the activation energies of each ettringite decomposition events were determined by the isoconversional methods of Ozawa-Flynn-Wall, Friedman, and Kissinger-AkahiraSunose. The modeling revealed that the activation energy varied from *50 kJ mol -1 , characteristic of mass transfer control steps, to *150 kJ mol -1 , which is typical of chemical control, as the temperature increased and the ettringite structure lost water. A total of 32 mol of water was released equivalent to 43.1 % of the initial sample mass.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetic and thermal decomposition of ettringite synthesized from aqueous solutions

Guimarães

Oliveira

Leão

2016

J Therm Anal Calorim

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“…Other internal sources of sulfate include pozzolana, admixtures or soil contamination e.g. sulfuric acid (Lee et al, 2005b).…”

Section: Sulfate Sourcesmentioning

confidence: 99%

Performance assessment of stabilised/solidified waste-forms

Antemir¹

2005

Stabilisation/Solidification Treatment and Remediation

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“…Some of these studies remark the important economic, social and risk related repercussions of using the contaminated rocks in concrete (2)(3)(4)(5)(6)(7). Figure 1 shows the case of the downstream face and the galleries of the Graus Dam (Spain), which shows severe cracking and movements due to the ISA.…”

Section: Introductionmentioning

confidence: 99%

Evolution of pyrrhotite oxidation in aggregates for concrete

Oliveira¹,

Cavalaro²,

Aguado³

2014

Mater. construcc.

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Rocks containing pyrrhotite bands are sometimes used to produce concrete. These rocks oxidize and produce long-term expansive reactions that damage concrete structures, leading to important economic and risk related repercussions. The present study analyses several aspects that affect the oxidation process of the aggregate such as the existence of preferential paths for the entrance of the oxidizing agent and the conversion process of the chemical elements involved in the reaction. For that, host rock samples containing pyrrhotite were investigated by scanning electron microscopy and energy dispersive spectroscopy. The results shows that the pyrrhotite appears in bands that create planes of weakness and present cracks that serve as preferential paths for the entrance of oxygen. Furthermore, a new representation is proposed for the oxidation process. RESUMEN:Evolución de la oxidación de la pirrotina presente en áridos para hormigón. Rocas con bandas de pirrotina han sido usadas para producir áridos destinados a la fabricación de hormigones. Las mismas son susceptible a un fenómeno de oxidación que a largo plazo produce la degradación del material, llevando a importantes repercusiones económica y en cuanto a la seguridad. El presente estudio evalúa la influencia de diferentes aspectos que pueden afectar dicho proceso de oxidación del agregado, tales como la existencia de caminos preferentes para la entrada del agente oxidante y los elementos químicos involucrados en la reacción. Para ello, muestras de roca con pirrotina han sido analizadas mediante microscopía electrónica de barrido. Los resultados indican que la pirrotina aparece en bandas que dan lugar a planos de debilidad y fisuración. Esas fisuras actúan como caminos preferentes a la entrada del oxígeno. Asimismo, con base en los análisis realizados se ha propuesto una nueva representación para el proceso de oxidación.

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The formation and role of ettringite in Iowa highway concrete deterioration

Cited by 95 publications

References 39 publications

Kinetic and thermal decomposition of ettringite synthesized from aqueous solutions

Kinetic and thermal decomposition of ettringite synthesized from aqueous solutions

Performance assessment of stabilised/solidified waste-forms

Evolution of pyrrhotite oxidation in aggregates for concrete

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