Pozzolane

POX. See Polyoxetane Poxvindae Poynting correction Poynting factor POY nylon yarn Pozzolans... 

Petroleum. Apart from its use ia petrochemicals manufacture, there are a number of small, scattered uses of lime ia petroleum (qv) production. These are ia making red lime (drilling) muds, calcium-based lubricating grease, neutralization of organic sulfur compounds and waste acid effluents, water treatment ia water flooding (secondary oil recovery), and use of lime and pozzolans for cementing very deep oil wells. 

Some of the most common stabilization—soHdification processes are those using cement, lime, and pozzolanic materials. These materials are popular because they are very effective, plentiful, and relatively inexpensive. Other stabilization—soHdification technologies include thermoplastics, thermosetting reactive polymers, polymerization, and vitrification. Vitrification is discussed in the thermal treatment section of this article and the other stabdization—soHdification processes are discussed below. 

Major categories of industrial waste solidiflcation/stabilization systems are cement-based processes, pozzolanic processes (not including cement), thermoplastic techniques, organic polymer techniques, surface encapsulation techniques, and self-cementing techniques (for high calcium sulfate sludges). Vitrification (discussed previously) can also be considered a solidification process. 

Pozzolanic Applicable Applicable Applicable Applicable Applicable Applicable... 

Applicability Pozzolanic processes are suitable for high-volume, low-toxicity wastes containing radioactive materials or heavy metals with an organic content below 10 percent. 

Certain treatment systems fall in the category of cement-pozzolanic processes and have been in use for some time outside the U.S. In these systems, both cement and lime-siliceous materials are used in combination to give the best and most economical containment for the specific waste being treated In general, the bulk of the comments (under both classifications above) hold for techniques using a combination of treatment materials. 

Adding large quantities of pozzolan, ceramic microspheres or nitrogen. These materials lighten the slurry because they have lower specific gravities than the cement. 

The most common low-specific-gravity solids used to reduce cement slurry specific weight are bentonite, diatomaceous earth, solid hydrocarbons, expanded perlite and pozzolan. It may not be possible to reduce the cement slurry specific weight enough with the above low-specific-weight materials when very weak formations are exposed. In such cases nitrogen is used to aerate the mud column above the cement slurry to assist in further decreasing the hydrostatic pressure. 

Expanded Perlite. Expanded perlite requires a great deal of water to be added to the slurry when it is used to reduce the specific weight of a slurry. Often perlite as an additive is used in a blend of additives such as perlite with volcanic glass fines, or with pozzolanic materials, or with bentonite. Without bentonite the perlite tends to separate and float in the upper part of the slurry. 

Pozzolan. Diatomaceous earth is a type of pozzolan. Pozzolan refers to a finely ground pumice or fly ash that is marketed as a cement additive under that name. The specific gravity of pozzolans is slightly less than the specific gravity of cement. The water requirements for this additive are about the same as for cements. Only a slight reduction in specific weight of a slurry can be realized by using these additives. The cost of pozzolans is very low. 

Sarp Tuncoku, S., E. N. Caner-Saltik, and H. Boke (1998), Pozzolanic properties of some medieval masonry mortars, 31st Int. Symp. Archaeometry Abstracts, Budapest, pp. 139-142. 

Petrifix A process for solidifying aqueous wastes, converting them to a solid form suitable for landfill. Cementitious additives are used, based on the compositions used by the Romans for making Pozzolanic cements. Developed by Pec-Engineering, Paris, France. In 1979 it had been used in France and Germany. 

Power tubes, microwave, 26 520 Power washing, of metal surfaces, 26 213 Poxviruses, 3 136 Poynting correction, 8 746 24 666 Pozzolanic materials, in hazardous waste management, 25 823 Pozzolans, 5 478—479, 493 U.S. shipments, 5 498t PPA resins, properties of, 10 216t PPE-PS blends, 20 193 PPG-10 cetyl ether... 

Solidification of the upper layers can be accomplished by blending pozzolanic additives, modified clay, or stabilization reagents into moist soil and compacting the mass. Pozzolanic additives include such fixatives as portland cement, quick lime,... 

A less rigid pavement can be created by blending an asphalt-water-surfactant emulsion with the upper soil layers. During the curing process, the asphalt-water emulsion deteriorates, leaving the asphalt to bind the hydrocarbon contaminants and soil to create a low-permeability pavement. Asphalt-soil pavements tend to be less rigid than pozzolanic-soil structures. 

Mordenite and cHnoptiloHte are used in small volume in adsorbent applications including air separation and in drying and purification [24]. Natural zeolites have also found use in bulk applications as fillers in paper, in pozzolanic cements and concrete, in fertihzer and soil conditioners and as dietary supplements in animal husbandry. 

Fig. 3.22 The effect of pozzolan materials on the air-entraining agent dosage required to maintain the air content.

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