Cement, properties

Table 5.11. Effect of +)-tartaric acid on glass polyalkenoate cement properties...

Table 5.12. Ejfect of the various tartaric acids on glass polyalkenoate cement properties Crisp, Lewis Wilson, 1979)...

Even when modifiers are not necessary for cement formation, they can lead to improved cement properties. Kingery (1950b) also examined this effect. He found that optimum bonding was achieved with cations that had small ionic radii and were amphoteric or weakly basic, such as beryllium, aluminium, magnesium and iron. By contrast, cations that were highly basic and had large ionic radii, for example calcium, thorium and barium, had a detrimental effect on bonding. 

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. 

Effect of glass composition on cement properties As we have indicated previously, two types of glass have been used in dental silicate cements the obsolete oxide glass and the modem fluoride glass. Only four studies on glass composition and its relationship to cement property have been published (Wright, 1919 Crepaz, 1951 Manly et al.. 

Table 6.7. Effect of particle size of powder on cement properties Kent Wilson, 1971)...

Effect of liquid composition on cement properties The properties of dental silicate cements are affected both by the concentration of phosphoric acid and by the presence of metal salts. 

This sensitivity to water has practical implications. A cement liquid is stable in an atmosphere of 70 % relative humidity. It will gain water in more humid atmospheres and lose it to drier ones, and this will adversely affect cement properties (Paffenbarger, Schoonover Souder, 1938 Worner Docking, 1958 Wilson et al., 1970a). 

All commercial examples of phosphoric add solutions used in these cements contain metal ions, whose role has been discussed in Section 6.1.2. In the case of the dental silicate cement, aluminium and zinc are the metals added to liquids of normal commerdal cements and have a significant effect on cement properties (Table 6.8) (Wilson, Kent Batchelor, 1968 Kent, Lewis Wilson, 1971a,b). Aluminium accelerates setting for it forms phosphate complexes and is the prindpal cation of the phosphatic matrix. Zinc retards setting for it serves to neutralize the addic liquid - it... 

XIV. Crazing, cement properties and liquid composition. Journal of Dental Research, 50, 400-4. 

Cementing operations in oil and gas wells place demanding requirements on cement properties. In spite of this challenge, the drilling and completion industry has relied exclusively on conventional portland cement with a few modifications for its cementing needs. The properties of portland cement and its modifications used in the oil industry are discussed in Chapter 3 of Ref. [1]. 

A.D. Neve, V. Piddock, E.C. Combe, Development of novel dental cements. II. Cement properties, Clin. Mater. 9 (1992) 13-20. 

M.J. Bertolini, R.G. Palma-Gibb, M.A. Zaghete, R. Gimenes, Evaluation of glass ionomer cements properties obtained from niobium silicate glasses prepared by chemical process, J. Non-Cryst. Solids 351 (2005) 466 71. 

From other important cement properties the following should be mentioned ... 

On the end of aforementioned rules of classification the position should be taken on the methods of cement properties testing. It is, however, not necessary to justify that... 

Similarly cuprum enhances the clinkering process, however, worsens cement properties [215]. Chromium, bariitm, phosphoms, boron and titanium added in small quantities to raw materials increase cement strength after 3 days of hardening... 

There are some paste properties which influence the behaviour of fresh concrete. The workability of concrete mixture is the function of the rheological properties of paste which depend on the fine fraction content in cement. The yield stress value, being the measure of concrete mixture consistency at final stage of mixing, is increasing with the rise of cement specific surface area (Fig. 5.12). The initial setting time is significantly shorter in the case of this cement property. 

The determination which cement properties are controlling cement-admixture compatibility is of the key importance in resolving this problem. Therefore many studies dealing with this question have been carried out recently [385-393]. 

Locher, F.W. Influence of the Grinding Process on Cement Properties, w Advances in Cement Manufacture and Use. In Gartner, E. (ed.) Engineering Eoundation, New York (1988). 

The classic approach to the cement strength development was to increase the alite and CjA content, as well as the fineness of cement. The increase of silica modulus to about 3 and use of some minor components, mainly barium and boron results in further cement properties enhancement. The rate of hardening of these cements [121-123] is increasing with their specific surface in the range 4,400-4,600 cm /g and with K2SO addition (1.5 %), according to Grzymek s patent [124]. 

The results of investigations of the second group of belite cements properties, allowed to choose of the most advantageous compositions, given in Table 9.5. Beside... 

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