Cement components

Crisp and coworkers found that the development of surface crystallinity was related to the speed of set. The faster the reaction, the shorter was the inhibition period before surface crystallization took place. When the setting time of a cement was between two and three minutes, surface crystallinity developed in a few minutes. When it was seven minutes, surface crystallinity was delayed by three hours. The reaction rate was affected by the chemical composition and physical state of the cement components. Well-ignited zinc oxide, the presence of magnesium in the... 

Cement properties are affected by a number of factors. Some are determined by the manufacturer, for example the chemical composition of the cement components. Others are under the clinician s control. These include the powder/liquid ratio of the cement mix and the temperature of the surgery. Increase in either of these variables accelerates the reaction and affects properties. 

As expected [2-4], when the solid and liquid cement components were mixed, the anthracene-toluidine complex fluorescence increased in intensity over time as the cure proceeded and nonfluorescence pathways for energy disposal were blocked. Although the change in peak shape made it difficult to comment on the relative fluorescence intensity from the exciplex compared to that from independent molecules, it was clear that the exciplex... 

Although many Ca-rich fly ashes are self-cementing, strength gain is usually too slow for most practical applications. Moreover, aluminosilicate rich ashes are essentially unreactive with water. The most important application of fly ash is as a partial replacement for Portland cement. In this application, Portland cement furnishes much of the early strength, up to 1 month, while the high alkalinity of cement chemically activates the ash such that its slow reaction with cement components and water contribute increasingly to... 

Nonhazardous spent catalysts can be also reused in the production of bricks. Specifically, catalysts are crushed and decreased in size to form alumina/silica sand that can replace the sand used in the manufacture of bricks. Moreover, spent fluidized-bed catalysts can be reused as cement components. Specifically, the catalyst is used to replace clinker in the final grinding (Cardenosa el al., 1992). For the disposal of catalysts, the techniques presented in Section 4.3 can be largely applied. 

Deryagin B.V., Krotova N.A, Smilga V. P., Adhesion of solids. Moskva Nauka, 1973. Sichev M.M. Modem conceptions of the nature of cement components inorganic binders and the role of polymer formations. In Chemistry and technology of silicates and refractory materials. Institute of silicate chemistry of l.V. Grebenschikov Leningrad Nauka, 1989. 

ACGIH TLV TWA 2 mg(Al)/m3 SAFETY PROFILE Corrosive to the eyes, skin, and mucous membranes. When heated to decomposition it emits toxic fumes of POx. Used as an antacid and as a cement component, flux for ceramics, dental cement, glass, and gels. See also ALUMINUM COMPOUNDS and PHOSPHATES. 

Use Grinding and amalgamating fertilizer ingredients, clay mixtures, cement components, and similar products. 

When mechanical strength and thermal stability are paramount, as in steam reforming, this is accomplished by cementing components together with some type of ceramic cement, such as calcium aluminate. Early steam refonning catalysts were of this type. 

Late calcite cements are interpreted to have formed under relatively closed conditions, with cement components being derived from within the scale of the reservoir. In the central basin many of these calcites precipitated at near present-day reservoir conditions (> 90 C) and have Sr isotopic values consistent with current reservoir pore water values. 

Dolomite cement components were all sourced from outside the sand body, most probably from local or basinal mudrocks. Stable isotope data indicate a mixed organogenic-marine carbonate source, and precipitation at relatively low temperatures (s70°C, if pore fluids were sourced from clay mineral dehydration reactions during deep burial of Carboniferous mudrocks in the Rathlin basin 55°C if they were locally sourced). Thermobaric mass transfer was enhanced by tectonic pulsing and dolomite precipitation was driven by CO2 degassing. 

Baysical K p-Calcium silicate C.l. 77230 C.l. Pigment White 28 Calcium metasilicate Calcium silicate Calcium silicon oxide CS (cement component) EINECS 233-250-6 Florite Kemolit ASB 8 K ... 

Products and Uses Typically used in dental cements, cosmetics, paints and varnishes as a gelling agent, an antacid, and a cement component. 

F.R. Tay, D.H. Pashley, F.A. Rueggeberg, R.J. Loushine, R.N. Weller, Calcium phosphate phase transformation produced by the interaction of the Portland cement component of white mineral trioxide aggregate with a phosphate-containing fluid, J. Endod. 33 (2007) 1347-1351. 

Parallel with cement production development the significant progress in cement chemistry was achieved. The real revolution we owe to French scientist Le Chat-eher. This great chemist determined the phase composition of Portland cement clinker and the hypothesis of hydration process. Le Chatelier stated that, similarly as in the case of gypsum, the anhydrite cement components dissolve, the solution became oversaturated in relation to hydrates, which causes their crystallization [3],... 

The basis for rate cements to individual kinds is cement composition based principally on chemical determinations, to which belong insoluble residue and loss on ignition. They are principally linked with cement additions. For quantitative slag content determination from long time the light microscopy is used, and the accuracy of this method is assessed to be 5 % (Fig. 1.6). Lastly also the methods of separation in heavy liquids are recommended, based on the density differences of individual cement components clinker about 3.1 g/cm, slag 2.85 g/... 

The XRD studies of the interfacial transition zone (material produced by abrasion of paste layers) [16], as well as the SEM observations with EDS analysis [16] revealed the presence of transition zone surrounding the aggregate grains, determined by Maso as an aureole [ 10]. This relates to the former water film around the aggregate. This area shows higher w/c ratio and subsequently cement components can readily dissolve, as well as the hydration products crystallize from the solution. Calcium hydroxide crystallizes in this interfacial transition zone and the crystals are oriented in such a way that their (001) axis is perpendicular to the surface of aggregate, as it was reported by Barnes et al. [17]. The C-S-H is then formed and the two products occur together as a duplex film about 1 pm thick (Fig. 6.7). 

The construction of interfacial transition zone aroiuid the reinforcement in concrete is very similar to the aggregate paste interface. This is presumably the consequence of locally occurring higher w/c ratio, promoting dissolution of cement components and crystallization of cement hydration products from the liquid phase. This interfacial transition zone reveals also higher porosity and lower strength than the bulk cement matrix. 

The fluidized bed fly ash does not comply with the PN-EN 197-1 Standard as cement component and can be used only as filler, in amount not exceeding 5 %. However, the fluidized bed fly ash can used as set controlling agent, because of anhydrite content. This ash does not fulfill also PN-EN 450-1 Standard requirements as an addition to concrete. In Table 7.6 the contents of particular components in fluidized bed fly ash and bottom ash are given [130]. 

Pre-mixed products are the easiest to use because they do not require any mixing and any transfer into an appropriate delivery system. Moreover, there is no time constraint to use the product once it is open. However, pre-mixing is not a versatile approach to deliver a product, since the mixture composition is already pre-defmed. Moreover, it is not adapted to CPC formulations. Presently, only two methods have been proposed to package ready-to-use cement formulations. First, the reactive cement components are combined with a non-aqueous liquid to form a non-reactive pasty mixture. Reaction then occurs in vivo, when the non-aqueous hquid is slowly replaced with physiological fluids. Unfortunately, the setting reaction is difficult to control and the mechanical properties are poor." The second approach is to freeze down the cement components." However, it is not clear how injectable such mixtures would be and how the... 

Uses Catalysis thixotropy textile, cosmetic, and grease additive antiperspirant water repellents chemical reagent zirconium salts in lakes and toners of acid and basic dyes oilfield acidizing aid clay stabilizer (oil-well stimulation) thixotropic oil-well cement component... 

Qualitatively, the trends observed for cemented components also appear to be applicable to modular acetabular components, evaluated using current computer-assisted wear measurement techniques (Tables 5.2 and 5.3, and Figure 5.11). The box and whisker plots shown in Figure 5.11 compare the linear... 

Whether in the hip or the knee, for osteolysis to expand, wear debris particles need access to the periprosthetic bone. From review of the ortiiopedic knee literature, it appears that cemented fixation of knee components is an effective barrier to particle access, and explains the lower incidence of osteolysis in studies with cemented components (Table 8.3). In this regard, much of the knee... 

Two years after implantation of femoral components made of Ti-6A1-4V, the titanium and aluminium concentrations measured in the synovial fluid were higher for cemented components than for the uncemented (200 p.m HA, or porous Ti coatings) components (Karrholm et ai, 1994). Table 9.10 gives the data for the synovial fluid and the aluminium concentrations in serum and urine. No significant concentrations of vanadium were found in any of the samples, which was also the case for titanium in serum and urine. Fast clearance of vanadium from the synovial fluid, due to high solubility of vanadium complexes, and formation of stable titanium compounds, e.g. titanium phosphates (Ribeiro et al, 1995), might be reasonable explanations for these findings. 

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