An alkali-activated blend of aluminum cement and class F fly ash is an attractive solution for geothermal wells where cement is exposed to significant thermal shocks and aggressive environments. Set-control additives enable the safe cement placement in a well but may compromise its mechanical properties. This work evaluates the effect of a tartaric-acid set retarder on phase composition, micros...

Tartaric acid (TA) changes short-term mechanical behavior and phase composition of sodium-metasilicate activated calcium-aluminate cement blend with fly ash, type F, when used as a set control additive to allow sufficient pumping time for underground well placement. The present work focuses on TA effect on self-healing properties of the blend under steam or alkali carbonate environments at 270 ...

in this study, slag penetration into a magnesia refractory monolithic was investigated by the crucible test method. a synthetic calcium aluminate slag system has been used to study commercial magnesia mix refractory for 1, 2, 3, 4, 5 and 6 hours at 1450°c and 1600°c. it has been shown that the penetration rate is controlled by a diffusion mechanism at 1450°c. in this case, capillaries are the ...

calcium aluminates (ca) are the most important hydraulically setting cements used for preparing refractory castables, because they develop high strength at very early ages after placements.  the anhydrous phases of this kind of cements are ca, ca2 and traces of c12a7 and alpha-alumina. the major hydraulic phase in all of the ca cements including ciment fondue is ca. once hydrated, it starts to ...

Calculation of chemical equilibria involving a liquid requires a full knowledge of chemical potentials (or activities) of all the oxide components present in the liquid phase. This is a rigorous requirement compared to that for solid compounds, where only total free energies need to be known in order to calculate their stabilities relative to other compounds; obviously the difference stems from...

Alumina composites containing in-situ-formed hexaluminate (LaAl,,018, LaMgAl,,O,,, SrAl12019, and Mg,NaAl,,O,) platelets can be pressureless-sintered to high density. The grain morphology of the aluminates can be controlled by composition. A peak toughness 50% higher than that of alumina is obtained at 30 vol% aluminates, with a modest reduction (10%) in hardness and Young’s modulus. Although c...

0921-8831/$ see front matter 2011 The Society of doi:10.1016/j.apt.2011.11.004 ⇑ Corresponding author. Address: School of Metallu ing, University of Tehran, P.O. Box 14395-1491, Tehran fax: +98 21 88006076. E-mail address: [email protected] (S. Sheibani). In this paper, the possibility of mechano-chemical synthesis, as a single step process for preparation of nanostructured nickel aluminate sp...

The purpose of this study was to evaluate the physical properties and hydration evolution of calcium aluminate cement (CAC) compositions containing an advanced dispersant. The compressive strength, dimensional change, apparent porosity and quantitative X ray diffraction analysis (XRD) of the cement pastes were carried out over 1-15 days of curing (with the samples immersed in distilled water) a...