Specifications cement

Marmor-kalk, m. lime from marble, -kiesel, m. a kind of hornstone. -lack, m. marble varnish. -mehl, fi. marble dust, -papier, n. marbled paper, -weiss, n. whiting (as a pigment). -zement, m. marble cement specif., Keene s cement. 

Cement Specific surface area Quantity of admixture required (ml 0.0368 m batch) for 4% air... 

Cement Ordinary portland cement (specific gravity 3.16, specific surface area 327,000 mm2/g)... 

Density. A suspension of portland cement particles in water can only be used in a narrow density range. Acceptance tests for oil well cements are run at a specified density within this narrow range. For example, class G cements are mixed at 44% water by weight of cement (BWOC) that, for an average cement specific gravity of 3.15, gives a solid volume fraction of 42% and a density of 1.89 g/cm3 or 15.8 lb/ gal. As density decreases below or increases above this optimum value, such a suspension is less and less stable (sedimentation) or more and more viscous. Therefore, it is necessary to add other material(s) to the suspension to adjust its density in a wider range. 

Cement ordinary portland cement (specific gravity,... 

Fig. 4.50 Specific surface of cement vs. time of grinding. The continuous line—real curve the dashed lines show the beginning of agglomeration and the end of cement specific surface area increase during grinding...

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. 

Given the inconsistency of cement specifications, it is not hard to understand the frustration it caused cement manufacturers. Writing in his 1898 book, American Cements, natural cement producer and proponent Uriah Cummings tells us that ... 

During the 1920s the following three national specifications for asphalt cements were pubHshed (/) Federal specifications, adopted in 1925 (2) the American Association of State Highway Transportation Officials (AASHTO) specifications, adopted in 1924, revised in 1926 and (2) ASTM specifications, adopted in 1922 to 1926, withdrawn in 1939, and re-issued in 1947. 

Specifications for paving asphalt cements usually include five grades differing in either viscosity or penetration level at 60 °C (Table 8) (ASTM D496). Susceptibihty of viscosity to temperature is usually controlled in asphalt cement by viscosity limits at a higher temperature such as 135 °C and a penetration or viscosity limit at a lower temperature such as 25 °C. 

ASTM C150 Standard Specification for Pordand cement defines eight types of Pordand cement produced to meet the performance requirements of different appHcations. 

The Tj-carbides are not specifically synthesized, but are of technical importance, occurring in alloy steels, stelUtes, or as embrittling phases in cemented carbides. Other complex carbides in the form of precipitates may form in multicomponent alloys or in high temperature reactor fuels by reaction between the fission products and the moderator graphite, ie, pyrographite-coated fuel kernels. 

The theoretical energy requirement for the burning of Portiand cement clinker can be calculated from the heat requirements and energy recovery from the various stages of the process. Knowledge of the specific heats of the various phases, and the heats of decomposition, transformation, and reaction then permits calculation of the net theoretical energy requirement of 1760 kj (420 kcal) for 1 kg of clinker from 1.55 kg of dry CaCO and kaolin (see Clays) (8). 

Special purpose and blended Portland cements are manufactured essentially by the same processes as ordinary Portland cements but have specific compositional and process differences. White cements are made from raw materials of very low iron content. This type is often difficult to bum because almost the entire Hquid phase must be furnished by calcium aluminates. As a consequence of the generally lower total Hquid-phase content, high burning-zone temperatures may be necessary. Past cooling and occasionally oil sprays are needed to maintain both quaHty and color. 

Portland cements are manufactured to comply with specifications estabUshed in each country (70). In the United States, several different specifications are used, including those of the American Society for Testing and Materials and American Association of State Highway and Transportation Officials (AASHTO). The ASTM aimuaHy pubhshes test methods and standards (24), which are estabhshed on a consensus basis by its members which include consumers and producers. 

Oil well cements (78) are usually made from Pordand cement clinker and may also be blended cements. The American Petroleum Institute Specification for Materials and Testing for Well Cements API Specification 10) (78) includes requirements for nine classes of oil well cements. They are specially produced for cementing the steel casing of gas and oil wells to the walls of the bore-hole and to seal porous formations (79). Under these high temperature and pressure conditions ordinary Pordand cements would not dow propedy and would set prematurely. Oil well cements are more coarsely ground than normal, and contain special retarding admixtures. 

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