Cement types

Type S po22olan-modified Portland cement. Type I (PM) and slag-modified Portland cement. Type I (SM). 

ASTM C845 Type E-I (K) expansive cement manufactured ia the United States usually depends on aluminate and sulfate phases that result ia more ettriagite formation duriag hydration than ia normal Portland cements. Type K contains an anhydrous calcium sulfoaluminate, C A SI. This cement can be made either by iategraHy burning to produce the desired phase composition, or by intergrinding a special component with ordinary Portland cement clinkers and calcium sulfate. 

Marketing Patterns. The cement industry has reduced its dependence on bag (container) shipments (54.7% in 1950) and turned to the more labor-efficient bulk transport (96% in 1990). In addition, the amount of cement shipped by rail transportation declined from 75% of industry shipments in 1950 to less than 14% in 1990. Table 11 summarizes the shipment distribution by cement type. 

The ASTM specifications provide for five types of Portland cements Types I, II, III, IV and V they are manufactured for use at atmospheric conditions [165]. The API Classes A, B and C correspond to ASTM Types I, II and III, respectively. The API Classes D, E, F, G, H and J are cements manufactured for use in deep wells and to be subject to a wide range of pressures and temperatures. These classes have no corresponding ASTM types. 

In vitro studies by Wilson et al. (1986) using the impinging jet method show the EBA cement to be the least resistant of all the cement types to erosion in neutral solution. Clinical studies confirm this result and show that there is greater dissolution in the mouth than for other dental cements (Mitchem Gronas, 1978 Osborne et al., 1978 Andrews and Hembree, 1976 Shilling, 1977). Despite this, a clinical survey by Silvey and Myers... 

Table 3.11 Cement type and source can influence the volume of air obtained in both plain and air-entrained mixes...

Two factors affect the reaction of both the wet and dry processes, viz. (1) mix design and (2) the ambient conditions prevailing during the spraying of the concrete. Mix design factors include cement type and content, water- cement ratio, cement-admixture compatibility and the presence of other admixtures. Cements with higher C3A contents such as Types I and III give faster reactions than cement with low C3A contents such as Types IV... 

This shrinkage mechanism occurs only in pores within a fixed range of sizes. In pores larger than 50 nm the tensile force in the water is too small to cause appreciable shrinkage and in pores smaller than 2.5 nm a meniscus cannot form [122]. The amount of cement-paste shrinkage caused by surface tension depends primarily on the water-cement ratio, but it is also affected by cement type and fineness and by other ingredients (such as admixtures, and supplementary cementing materials) which affect pore size distribution... 

ASTM recognizes three types of retarding admixtures type B, which simply retards the hydration of Portland cement type D, which not only provides set retardation but also water reduction and type G, which is a retarding supeplasticizer. The materials that are generally used in these admixtures include ... 

Factors which affect the dosage rate are concrete temperature, initial slump (i.e. slump before the addition of the superplasticizer), cement type and content, the presence of other admixtures in the mix prior to the addition of the superplasticizer and the sequence of addition to the mix. The... 

Common objectives sought in the water-reduced high-strength application include (1) lowering of curing cost (2) reduced cement content while maintaining same workability and strength levels (3) the use of an alternative cement type, e.g., from Type III to Type I (4) the production... 

The lower water-cement ratio afforded by the use of a superplasticizer may be used to increase existing compressive strengths or to reduce cement content. Thus the use of superplasticizers may enable the precast producer to use lower cement content without reduction in mix workability and rate of strength development. The actual amount of cement reduction achieved will depend on the cement type used and the mix proportion used in the concrete. Previous work [63] indicates that even with low cement content (306 kg m 3) a normal dose of superplasticizer can accelerate 3- and 28-day strengths by 90% and 55%, respectively, over levels attained with a plain mix. Cement reductions in the range of 11-20% have been achieved in mixes with a cement content of 415 kg m, while maintaining desired strength... 

The accelerated carbonation reactions have also been shown to improve the immobilization properties of Portland cements used as radioactive was-teforms. The formation of carbonates eliminates the potential problem of radiolysis while at the same time improving the leaching resistance. The resulting carbonate matrix, which is more thermodynamically stable relative to the untreated cement, would also be preferred for the underground disposal of the wasteforms. Incorportion of fly ash into the cement-type wasteform further enhances the favorable properties of this waste type. 

A variety of colors of paper (all 12 colors of the color wheel, plus white, black, and gray) pencil ruler scissors glue or rubber cement typing paper or other paper suitable for mounting samples. 

Iodine concentration, mmol I/g dry cement Cement type... 

A number of recommendations pertaining to the requirements of concrete to be used in marine structures have been made [31-33], These include specification of cement type and cement contents of 400-500 kg nr3, a water-cement ratio of less than 0.45 and an air content of 4-7% depending on the maximum aggregate size. The concrete must be fully compacted and mix designed to have sufficient workability, yet have the lowest possible water-cement ratio. Such parameters usually involve mix modifications which include an admixture. 

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