Class H cement hydration at 180 °C and high pressure in the presence of added silica

Jupe, Andrew C.; Wilkinson, Angus P.; Lozano, Karen; Funkhouser, Gary P.

doi:10.1016/j.cemconres.2007.12.004

Cited by 95 publications

(43 citation statements)

References 21 publications

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“…The primary formed C-S-H gel converts to crystalline alpha dicalcium silicate hydrate (a-C 2 SH) or C 3 SH 1.5 (Jupe et al 2008;Mindess et al 1981;Taylor 1997). These phases are porous and weak, which leads to a deterioration in the compressive strength and concrete durability (Eilers et al 1983;Grabowski and Gillott 1989).…”

Section: Introductionmentioning

confidence: 99%

“…The hydration product features of autoclaved mixtures depend on many parameters, including the curing conditions, calcium to silica ratio (Ca/Si), and type of added silica (Bresson et al 2002;Eilers et al 1983;Hope 1981;Kołakowski et al 1994). It has been stated that, under autoclave conditions, the use of crystalline silica produces high strength compared to the use of amorphous silica (Assarsson and Rydberg1956;Grabowski and Gillott 1989;Jupe et al 2008;Luke 2004;Sanders and Smothers 1957;Yazici 2007). Additionally, it has been demonstrated that, at each autoclaving temperature, there is an optimum period of curing that results in good mechanical and physical properties (Hanson 1963;Menzel 1934;Neville 1973;Shi and Hu 2003;Yazıcı et al 2008).…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…Elevated temperature and pressure both accelerate cement hydration, reducing the time for the grout to thicken and set (Bensted, 2008;Jupe et al, 2008;Nelson and Guillot, 2006;Scherer et al, 2010;Shariar and Nehdi, 2014;Taylor, 1997;Zhang et al, 2010). Temperature has more influence over the reaction rate than pressure and also has a greater effect on the composition of the main cement hydrate phases formed.…”

Section: Introductionmentioning

confidence: 99%

Inorganic anions as retarders for deep borehole disposal grouts

Collier

Balboa

Milestone

et al. 2017

Advances in Cement Research

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Deep borehole disposal (DBD) provides an alternative to comparatively shallow mined repository concepts for many high-level radioactive wastes. Filling the annular space around the waste containers with cement grout will support them during placement and seal against ingress of groundwater. The elevated temperature and pressure ($120°C and 50 MPa) will cause acceleration of grout thickening and setting, so retardation is required. The DBD Research Group at The University of Sheffield has developed grouts based on class G oil well cement that use organic retarders, but their presence may increase the solubility of any radionuclides released from the waste packages. New DBD grout formulations using sodium phosphate and sodium borate as inorganic retarders are reported in this paper. To place the wet grout, the onset of thickening needs to be delayed for at least 4 h. Sodium borate was found to provide this retardation at 90°C (0·75% addition) and nearly retarded sufficiently at 120°C (1% addition). Sodium phosphate did not provide sufficient retardation at either temperature. Neither compounds influenced the phases formed, but may suppress the crystallisation of calcium silicate hydrates. This work demonstrates that the performance of these inorganic materials in this application is inferior to that of organic retarders.

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“…A number of studies reported that the use of crystalline silica performed better than amorphous silica under autoclave curing (Luke 2004;Jupe et al 2008). Autoclaving amorphous silica such as silica fume, fly ash and natural zeolite were reported to display lesser strength than autoclaving crystalline silica (Luke 2004).…”

Section: Introductionmentioning

confidence: 99%

Use of Fine Ground Dune Sand as a Supplementary Cementing Material

Alhozaimy

Alawad

Jaafar

et al. 2014

Journal of Civil Engineering and Management

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Abstract. The process of Portland cement production is associated with high consumption of energy and resources. Therefore, there is a need to replace the Portland cement with environmental friendly materials. This study was conducted to determine the feasibility of using ground dune sand as cement replacement materials under different curing conditions. Portland cement was replaced by ground dune sand at five levels of replacement (0-40% by weight). The compressive strength of mortar under standard and autoclave curing conditions and the influence of different autoclave temperatures and durations were investigated. The microstructure of selected mixtures was analyzed by XRD and SEM. Results showed that the compressive strength under the standard curing decreased as the level of replacement increased. However, under autoclave curing compressive strength increased as the content of ground dune sand increased. XRD and SEM revealed the absence of calcium hydroxide and the formation of secondary calcium silicate hydrate. The improvement of compressive strength and the absence of calcium hydroxide under autoclave curing indicated that the pozzolanic reaction between silica of dune sand and calcium hydroxide occurred.Keywords: dune sand, autoclave curing, pozzolanic materials, compressive strength, XRD, SEM.

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Class H cement hydration at 180 °C and high pressure in the presence of added silica

Cited by 95 publications

References 21 publications

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

Inorganic anions as retarders for deep borehole disposal grouts

Use of Fine Ground Dune Sand as a Supplementary Cementing Material

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