Development of microstructures in plain cement pastes hydrated at different temperatures

Kjellsen, Knut O.; Detwiler, Rachel J.; Gjørv, Odd E.

doi:10.1016/0008-8846(91)90044-i

Cited by 248 publications

(73 citation statements)

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“…This image also revealed that the hydrated products are associated with loose structures. These features explained the negative effect of the performance of the plain cement mixture cured under autoclave conditions (Alawad et al 2014;Bakharev et al 1999;Kjellsen et al 1991). For the M2 mixture, plate-like structures of tobermorite (C 5 S 6 H 5 ) with dense and closed network structures were observed, as shown in Fig.…”

Section: Morphological Studymentioning

confidence: 83%

“…10, all the blended mixtures yielded compressive strengths higher than that of the control (M1). The low compressive strength of M1 is attributed to the formation of lime-rich alpha dicalcium silicate hydrate (a-C 2 SH) (Bakharev et al 1999;Kjellsen et al 1991). The microstructure analysis of M1 showed the formation of fibrous-like hydrated products and loose structures.…”

Section: Compressive Strengthmentioning

confidence: 99%

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Effect of Autoclave Curing on the Microstructure of Blended Cement Mixture Incorporating Ground Dune Sand and Ground Granulated Blast Furnace Slag

Alawad

Alhozaimy

Jaafar

et al. 2015

International Journal of Concrete Structures and Materials

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Investigating the microstructure of hardened cement mixtures with the aid of advanced technology will help the concrete industry to develop appropriate binders for durable building materials. In this paper, morphological, mineralogical and thermogravimetric analyses of autoclave-cured mixtures incorporating ground dune sand and ground granulated blast furnace slag as partial cementing materials were investigated. The microstructure analyses of hydrated products were conducted using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), differential thermal analysis (DTA), thermo-graphic analysis (TGA) and X-ray diffraction (XRD). The SEM and EDX results demonstrated the formation of thin plate-like calcium silicate hydrate plates and a compacted microstructure. The DTA and TGA analyses revealed that the calcium hydroxide generated from the hydration binder materials was consumed during the secondary pozzolanic reaction. Residual crystalline silica was observed from the XRD analysis of all of the blended mixtures, indicating the presence of excess silica. A good correlation was observed between the compressive strength of the blended mixtures and the CaO/SiO 2 ratio of the binder materials.

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Section: Morphological Studymentioning

confidence: 83%

Section: Compressive Strengthmentioning

confidence: 99%

Effect of Autoclave Curing on the Microstructure of Blended Cement Mixture Incorporating Ground Dune Sand and Ground Granulated Blast Furnace Slag

Alawad

Alhozaimy

Jaafar

et al. 2015

International Journal of Concrete Structures and Materials

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“…[18] that a more porous and continuous pore structure is formed when curing occurs at elevated temperatures (see also Ref. [19]). The rapid formation of inner C-S-H hinders the hydration process: the filling of the capillary pores is less efficient.…”

Section: Temperature Effects On Volumetric Autogenous Shrinkage-propomentioning

confidence: 99%

“…This process occurs after the nucleationgrowing process, when the thickness of the C-S-H layers reduces the accessibility to the unreacted core of the grains [29,11]. It has been shown in the literature that an Arrhenius law was not suitable to describe correctly the temperature sensitivity within the second stage [28,19]. Therefore, the descending portion of the derivative curves has not been taken into account here for the calculation of E a .…”

Section: Calculation Of Apparent Activation Energy From Chemical Shrimentioning

confidence: 99%

Autogenous deformations of cement pastes

Baroghel-Bouny

Mounanga

Khelidj

et al. 2006

Cement and Concrete Research

165

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A micro-macro experimental study has been performed, from the end of mixing up to 2 years, on a set of plain cement pastes prepared with the same type I ordinary Portland cement (OPC) and various water-to-cement ratios (W/C), and cured at various constant temperatures. In this part I of the paper, volumetric autogenous shrinkage has been analysed in relation to various parameters characterizing the hydration process: chemical shrinkage, degree of hydration of the cement, Ca(OH) 2 content and Vicat setting times, within the early-age period (V24 h). The effects of the curing temperature (ranging from 10 up to 50 8C) have in particular been investigated. Its effects recorded on both the rate and the magnitude of volumetric autogenous shrinkage vs. time have pointed out the irrelevance of the usual maturity concept to describe such phenomenon within the whole early-age period. An improved maturity concept has hence been proposed. It is based on separating the early-age period in different phases and on using chemical shrinkage data for the calculation of the apparent activation energy applied to the prediction of autogenous deformations occurring after the setting period. Furthermore, micro-macro relationships have been pointed out, illustrating in particular the determining role of Ca(OH) 2 .

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“…Concrete cured under high temperatures, such as the steam-cured concrete coming from prefabrication plants, modifies the morphology of the hydrated silicates and shows a more crystalline and porous structure (19)(20)(21)(22)(23)(24). This procedure has been found to be detrimental to the scaling resistance of the concrete.…”

Section: Introductionmentioning

confidence: 99%

The influence of the curing conditions of concrete on durability after freeze-thaw accelerated testing

Al‐Assadi¹,

Casati²,

Gálvez³

et al. 2015

Mater. construcc.

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This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw cycles (ASTM C 666). The "potential" durability of concrete after testing is also studied. In countries with a continental climate, the curing of concrete in summer is performed under high-temperature and low-humidity conditions, and during the winter the concrete undergoes freezing and thawing. This paper shows the experimental results of the behaviour of concrete specimens cured under climatic summer conditions and then subjected to freeze-thaw cycles. Curing of the specimens includes conditions of good and bad practice in relation to wetting and protection of the concrete. Mechanical properties, cement hydration, volume and pore sizes, oxygen permeability, chloride diffusion and water penetration under pressure tests of the concrete are assessed. These tests were performed before and after the application of the freeze-thaw cycles. Statistical analysis of the correlation among variables is also included. RESUMEN: Influencia de las condiciones de curado del hormigón en su durabilidad tras los ensayos acelerados de ciclos hielo-deshielo.Este trabajo relaciona las condiciones de curado del hormigón con los daños causados por ciclos hielo-deshielo (ASTM C 666). Estudia la durabilidad "potencial" del hormigón dañado por este ensayo. En países con clima continental, el curado del hormigón en verano se realiza con alta temperatura y baja humedad, y durante el invierno sufre condiciones de hielo-deshielo. Se presentan los resultados experimentales de probetas de hormigón curadas bajo condiciones climáticas del verano y luego sometidas a ciclos hielodeshielo. El curado de las probetas incluye condiciones de buenas y malas prácticas en relación con el curado del hormigón. Se miden las propiedades mecánicas, grado de hidratación, volumen de poros y distribución de tamaños, permeabilidad al oxígeno, penetración de agua bajo presión y coeficiente de difusión de cloruros antes y después de la aplicación de los ciclos de hielo-deshielo. Se incluye un estudio estadístico para analizar la correlación entre las variables.

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Development of microstructures in plain cement pastes hydrated at different temperatures

Cited by 248 publications

References 1 publication

Effect of Autoclave Curing on the Microstructure of Blended Cement Mixture Incorporating Ground Dune Sand and Ground Granulated Blast Furnace Slag

Effect of Autoclave Curing on the Microstructure of Blended Cement Mixture Incorporating Ground Dune Sand and Ground Granulated Blast Furnace Slag

Autogenous deformations of cement pastes

The influence of the curing conditions of concrete on durability after freeze-thaw accelerated testing

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