Other Types of Cement

Other types of cements include anhydrite, barite, pyrite, iron hydroxides haematite, albite and apatite and are subordinate. 

A knowledge of the relevant high-temperature phase equilibria is necessary for understanding the factors that govern acceptable bulk compositions for Portland cement clinker, the conditions under which the latter can be manufactured, and the phase composition and microstructure of the resulting material. This chapter deals with these equilibria and with the phases to which they relate, with the exception of the major clinker phases, which were described in Chapter I. Some anhydrous phases primarily of interest in relation to other types of cement are also considered here. Principles underlying the preparation of anhydrous silicate, aluminate and other high-temperature phases are outlined. 

All the cements considered in this book fall into the category of hydraulic cements they set and harden as a result of chemical reactions with water, and if mixed with water in appropriate proportions continue to harden even if stored under water after they have set. Much the most important is Portland cement. Chapters I to 4 of the present work deal mainly with the chemistry of manufacture of Portland cement and with the nature of the resulting product. Chapters 5 to 8 deal mainly with the processes that occur when this product is mixed with water and with the nature of the hardened material. Chapters 9 to 11 deal with the chemistry of other types of cement, of admixtures for concrete and of special uses of cements. Chapter 12 deals with chemical and microstructural aspects of concrete, including ones relevant to processes that affect its durability or limit its service life. 

Other types of cement than those of Table 1.3 are available for special uses. These are for instance low heat cements to be used when low heat of hydration is desired such as in massive structures, sulfate-resisting cements to be used to increase the resistance of concrete to sulfate attack, expansive cements, quick setting cements, white or coloured cements, etc. [2]. 

Tungsten carbide (WC), the hard phase, together with cobalt (Co), the binder phase, forms the basic cemented carbide structure from which other types of cemented carbide have been developed. In addition to the straight tungsten carbide - cobalt compositions - cemented carbide may contain varying proportions of titanium carbide (TiC), tantalum carbide (TaC), and niobium carbide (NbC). These carbides are mutually soluble and can also dissolve a high proportion of tungsten carbide. Also, cemented carbides are produced which have the cobalt binder phase alloyed with, or completely replaced by, other metals such as iron (Fe), chromium (Cr), nickel (Ni), molybdenum (Mo), or alloys of these elements. 

Table 24.1 lists a range of pigments that may be used in combination with white or ordinary Portland cement in the production of colored cements. Even though Portland cement is the binder most widely used for this pttrpose other types of cement may also be employed, such as calcirrm alrrminate cement. 

Another similar application of isothermal calorimetry is the assessment of the thermal power at different curing regimes see Figure 2.11. Sealed conditions, which are the usual case in isothermal calorimetry, are compared to pastes with extra water added on top of the sample. This extra water causes an increase in cumulative heat and thus an increased hydration degree. The effect becomes more pronounced at lower w/c, where the samples tend to undergo self-desiccation. The same effect can be seen also with other types of cement, such as calcium sulfoaluminate cements. As this type of cement needs a higher w/c for complete hydration compared to Portland cement (around 0.5-0.6 instead of 0.4 see Winnefeld and Lothenbach 2010), the effect of the extra water is already very evident at a w/c of 0.7 see Figure 2.12. 

Portland cement is classified as a hydrauHc cement, ie, it sets or cures in the presence of water. The term Portland comes from its inventor, Joseph Aspdin, who in 1824 obtained a patent for the combination of materials referred to today as Portland cement. He named it after a grayish colored, natural limestone quarried on the Isle of Portland, which his cured mixture resembled. Other types of hydrauHc cements based on calcium materials were known for many centuries before this, going back to Roman times. Portland cement is not an exact composition but rather a range of compositions, which obtain the desired final properties. The compounds that make up Portland cements are calcium siHcates, calcium aluminates, and calcium aluminoferrites (see ). 

Other Types of Portland Cements. White Portland cementis standard Type I or III Pordand cement with raw materials selected and controUed to have negligible amounts of Hon and manganese oxides, which impart the gray color. The white Pordand cement is used in decorative and architectural appHcations like precast curtain waUs, terra22o surfaces, stucco, tile grout, and decorative concrete. 

A diagnosis of possible damage should be made before beginning repairs with other construction measures [48,49]. There should be a checklist [48] of the important corrosion parameters and the types of corrosion effects to be expected. Of special importance are investigations of the quality of the concrete (strength, type of cement, water/cement ratio, cement content), the depth of carbonization, concentration profile of chloride ions, moisture distribution, and the situation regarding cracks and displacements. The extent of corrosion attack is determined visually. Later the likelihood of corrosion can be assessed using the above data. 

Because cement kilns are so good at destroying organic chemical wastes, emissions of dioxins - or any other type of products of incomplete combustion (PIC) - are so low they pose no danger to the environment. In the case where some of the hazardous waste fuels used contain toxic dioxin, the cement kiln temperatures of 1650°F will destroy dioxins in less than one second. Because cement kilns operate at much higher temperatures (at least 2450°F), and because the burning wastes have an average residence time in the kiln of at least two seconds, any dioxins are destroyed. However, dioxin waste is never accepted by Southdown for use in its cement kilns. 

The data presented in this section illustrate that, with the exception of those accelerating water-reducing admixtures containing calcium chloride, there is an abundance of evidence to support the conclusion that water-reducing admixtures of lignosulfonate chemical form certainly will not accelerate any kind of corrosion with reinforcement and, when used to reduce the water-cement ratio, will form a more permeable and durable protective cover for the reinforcement. In view of the chemical nature of the other types of materials such as the hydroxycarboxylic acids and hydroxylated polymers, it seems most likely that these materials too would have no deleterious effect in this respect. 

Mix proportion aspects that should be considered in the design of highly flowable mixtures include (1) cement content (2) fines content (3) type of superplasticizer (4) the presence of other admixtures in the mix (5) type of cement or cementitious material (6) dosage of the admixture (7) sequence... 

Cements that harden by the loss of solvent generally are to be avoided because the solvent can be lost only be diffusion thru the expl. Diffusion may be slow and the solvent may modify the properties of the expl. Two types of cement that have been used for this purpose are catalytic setting cements, like epoxy resins, and contact cements. Compatibility of the materials to be used should be checked. Compatibility of epoxy resins with most explosives depends upon the catalyst or hardener used (Ref 8). Data regarding bond strengths and other pertinent properties also have been compiled (Refs 5 6)... 

Examination of Sulphlex-233 mixtures with other types of aggregates generally have confirmed the results presented here. Sulphlex-233 mixtures can meet or exceed most Marshall design and compressive strength criteria at either equal volume or equal weight replacement of asphalt cement, but "optimum" mixtures are obtained at or near the equal volume replacement level. The Sulphlex-233 mixtures are in many cases susceptible to water damage, and the use of tall oil as an anti-strip additive has been recommended where indicated. 

Dry process cement production facilities often have several other types of manufacturing equipment designed to increase fuel efficiency. First, many dry process kilns add a preheater to the feed end of the kiln to begin heating of the feed prior to its entrance to the kiln. Two main types of preheaters exist, the suspension preheater and the traveling grate preheater both use hot, exiting kiln air to facilitate a more efficient heat transfer to the feed than could occur in the feed end of the kiln itself.1 This... 

Particulate composites are used in greater volume than any others because concrete is a particular composite. In many ways, concrete is the archetype of this class of composites. It consists of particles or aggregates of various sizes almost always of mineral materials, bonded together by a matrix of an inorganic cement originally mixed with and hardened by its chemical reaction to water. Many types of particles are employed, at least five different types of Portland cements and several other types of inorganic cements act as binders. 

The great majority of Portland cements made throughout the world are designed for general constructional use. The specifications with which such cements must comply are similar, but not identical, in all countries and various names are used to define the material, such as OPC (Ordinary Portland Cement) in the UK, or Type I Portland Cement in the USA. Throughout this book, we shall use the term ordinary Portland cements to distinguish such general purpose cements from other types of Portland cement, which are made in smaller quantities for special purposes. 

Other types of admixtures used with calcium aluminate cements include water reducers and superplasticizers (Section 11.4), which also act as retarders, and thickening agents, such as carboxymethylcellulose. Complex formulations may be used for special purposes for example, a ready-mix mortar for high-performance road repair might contain 55% Ciment Fondu and 45% sand, with glass fibre, aluminium powder, Li2C03, sodium gluconate and methyl ethyl cellulose (M93). 

Polymeric fibers are popular for reinforcing concrete matrices because of their low density (more number of fibers for a prescribed volume fraction), high tensile strength, ease of dispersion, relative resistance to chemicals, and relatively low cost compared to other kinds of fibers. Polypropylene and polyolefin fibers are typically hydrophobic, resulting in a relatively poor bond with concrete matrices compared to some other types of fibers. Treatment of polypropylene with an aqueous dispersion of colloidal alumina or silica and chlorinated polypropylene enhances the affinity of these fibers toward cement particles. Treatment of polypropylene fibers with a surface-active agent provides better dispersion of the fibers and a stronger bond between cement and fiber. The earlier attempts at surface treatments of polypropylene fibers have had only limited success and have not been commercially attractive. 

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