Properties of type K expensive cement of pure components II. Proposed mechanism of ettringite formation and expansion in unrestrained paste of pure expansive component

Bentur, A.; Ish-Shalom, M.

doi:10.1016/0008-8846(74)90043-x

Cited by 82 publications

(19 citation statements)

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“…The effect of moisture content on expansive pressure development is also critical. The requirement of higher degree of hydration in the presence of greater water contents [51] has been explained by Shalom's spherical model [55,57,66]. The mechanism described here has a close resemblance to the explanation given by Chatterji [56], which also explains the large pressure increments occur in SCDAs in the presence of lower moisture content.…”

Section: Volume Expansion Mechanismsupporting

confidence: 68%

“…It is, therefore, obvious that expansive pressure develops in SCDA is dependent on the degree of hydration of CaO in the demolition agent. The volumetric expansion in expansive cement is therefore caused by hydration of CaO producing Ca(OH)2, ettringite crystals and CaSO4 [40,48,[55][56][57][58] leading to a gradual development of expansive pressures in the cement existing under a confinement. Figure 1.…”

Section: Chemical Componentsmentioning

confidence: 99%

“…This, however, may vary under field conditions due to the possible heat dissipation into the surrounding environment [40]. A further volumetric expansion can be observed in SCDA by the formation of ettringite crystals (Equation (2)) which are formed at high concentrations of hydrated lime [48,55,58]:…”

Section: Chemical Componentsmentioning

confidence: 99%

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An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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Global energy and material consumption are expected to rise in exponential proportions during the next few decades, generating huge demands for deep earth energy (oil/gas) recovery and mineral processing. Under such circumstances, the continuation of existing methods in rock fragmentation in such applications is questionable due to the proven adverse environmental impacts associated with them. In this regard; the possibility of using more environmentally friendly options as Soundless Chemical Demolition Agents (SCDAs) play a vital role in replacing harmful conventional rock fragmentation techniques for gas; oil and mineral recovery. This study reviews up to date research on soundless cracking demolition agent (SCDA) application on rock fracturing including its limitations and strengths, possible applications in the petroleum industry and the possibility of using existing rock fragmentation models for SCDA-based rock fragmentation; also known as fracking. Though the expansive properties of SCDAs are currently used in some demolition works, the poor usage guidelines available reflect the insufficient research carried out on its material's behavior. SCDA is a cementitious powdery substance with quicklime (CaO) as its primary ingredient that expands upon contact with water; which results in a huge expansive pressure if this CaO hydration reaction occurs in a confined condition. So, the mechanism can be used for rock fragmentation by injecting the SCDA into boreholes of a rock mass; where the resulting expansive pressure is sufficient to create an effective fracture network in the confined rock mass around the borehole. This expansive pressure development, however, dependent on many factors, where formation water content creates a negative influence on this due to required greater degree of hydration under greater water contents and temperature creates a positive influence by accelerating the reaction. Having a precise understanding of the fracture propagation mechanisms when using SCDA is important due to the formation of complex fracture networks in rocks. Several models can be found in the literature based on the tangential and radial stresses acting on a rock mass surrounding an SCDA charged borehole. Those fracture models with quasi-static fracturing mechanism that occurs in Mode I type tensile failure show compatibility with SCDA fracturing mechanisms. The effect of borehole diameter, spacing and the arrangement on expansive pressure generation and corresponding fracture network generation is important in the SCDA fracturing process and effective handling of them would pave the way to creating an optimum fracture network in a targeted rock formation. SCDA has many potential applications in unconventional gas and oil recovery and in-situ mining in mineral processing. However, effective utilization of SCDA in such application needs much extensive research on the performance of SCDA with respect to its potential applications, particularly when considering unique issues arising in using SCDA in different ...

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Section: Volume Expansion Mechanismsupporting

confidence: 68%

Section: Chemical Componentsmentioning

confidence: 99%

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An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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“…The swelling deformation is decoupled from the self-desiccation due to its fundamentally different underlying cause. Several mechanisms are generally described to explain the early age swelling of cementbased materials [24][25][26][27][28]. It has already been established that for the studied compositions, the origin of the swelling deformation is not related to a measurement artefact, to the absorption of bleeding water, to the adsorption of water by fillers, nor to the formation of portlandite [14].…”

Section: Swelling Deformationmentioning

confidence: 99%

Unified modelling of the temperature effect on the autogenous deformations of cement-based materials

Carette

Staquet

2018

Cement and Concrete Composites

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Temperature effects are of primary importance for designing concrete structures. Some of the early age temperature effects on the concrete behaviour can be accurately taken into consideration by well-known maturity functions. However, the effect of temperature on the autogenous deformations development is more complex, and results in contradictory evidence. This paper studies the influence of various isothermal curing temperatures from 10°C to 30°C on the autogenous deformations of concrete. Binary and ternary binders containing up to 30% of limestone filler and 70% of blast-furnace slag are studied. The amplitude of both the self-desiccation deformation and the early age swelling deformation are observed to decrease with increasing temperature, whatever the binder nature. Mechanisms for this observation are suggested, and a corresponding model is developed. The effect of the binder nature, age and temperature on the autogenous deformations is assessed with this model. Based on this new model, it is shown that the effect of temperature on the autogenous deformation development can be either beneficial or detrimental, depending on the nature of the binder.

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“…In this respect, calcium sulfoaluminate has been known as a low-CO 2 alternative to Portland cement. Calcium sulfoaluminate consists mainly of ye'elimite (C 4 A 3 S), which exhibits rapid strength gain and controlled expansion [6][7][8]. It is known that ye'elimite hydrates to form ettringite (C 6 AS 3 H 32 ), which can give expansion [4].…”

Section: Introductionmentioning

confidence: 99%

Hydration of Calcium Sulfoaluminate-Based Binder Incorporating Red Mud and Silica Fume

Jun

Kim

2019

Applied Sciences

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This study investigated the properties of hardened pastes made with calcium sulfoaluminate expansive agent (CSA), red mud, and silica fume. Five different ratios of 10:90, 20:80, 30:70, 40:60, and 50:50 were applied as the weight ratios of CSA and red mud. Red mud was replaced with 0, 5, and 10% silica fume by weight. Compressive strength, drying shrinkage, XRD, MIP, and SEM/EDS of the hardened pastes were performed. The results indicated that as the amount of CSA increased (i.e., as the amount of red mud decreased) up to 30%, sample strengths showed a tendency to increase. The main reaction product of the pastes was expansive ettringite, which was formed from the consumption of ye’elimite, anhydrite, gypsum, and Ca(OH)2. It was expected that C-S-H would be formed by the reaction of C2S in red mud; however, C-S-H phase was not present, and the pozzolanic activity due to the use of silica fume did not occur. The increase of CSA replacement level was effective for controlling the drying shrinkage of the samples. However, 50% replacement level of CSA induced excessive expansion, leading to the reduction in strength. It was found that the excessive expansion in the sample was reduced by the addition of silica fume.

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Properties of type K expensive cement of pure components II. Proposed mechanism of ettringite formation and expansion in unrestrained paste of pure expansive component

Cited by 82 publications

References 3 publications

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

Unified modelling of the temperature effect on the autogenous deformations of cement-based materials

Hydration of Calcium Sulfoaluminate-Based Binder Incorporating Red Mud and Silica Fume

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