High alumina cement composition

Concrete is a particulate composite of stone and sand, held together by an adhesive. The adhesive is usually a cement paste (used also as an adhesive to join bricks or stones), but asphalt or even polymers can be used to give special concretes. In this chapter we examine three cement pastes the primitive pozzolana the widespread Portland cement and the newer, and somewhat discredited, high-alumina cement. And we consider the properties of the principal cement-based composite, concrete. The chemistry will be unfamiliar, but it is not difficult. The properties are exactly those expected of a ceramic containing a high density of flaws. 

Compositions of high-alumina cement containing quartz or glass, calcium carbonate, microsilica, carbon black, iron oxide red mud or screened fly ash, and styrene-butadiene latex have been described [141,1803,1804]. 

Risch A, Pollmann H, Ecker M (1997) Application of Portland cement and high alumina cement for immobilization/solidification of a waste model composition. Proceedings of the 10th ICCC, Goteborg, Sweden, vol. 4,4iv044,8 pp... 

The phase composition and texture of high-alumina cement produced by solid-state sintering will also be affected by the production process used, but to a lesser extent. 

Midgley, H.G. (1980) The relationship between cement clinker composition and strength recovery of hydrating high alumina cement during conversion, in Proceedings 7th ICCC, Paris, Vol. 3, pp. V68-70. 

The catalysts were prepared by mixing hydrozocarbonates of metals (MHO with calcium monoaluminate (CaAl204), calcium dialuminate (CaAUO ) or high alumina cement (CaAl204 + (laAl407) in aqueous or ammonia-aqueous medium. Phase composition and dispersity of the catalysts at different steps of the preparation were determined by X-ray diffraction... 

High alumina cements (also called calcium aluminate cements) are obtained from bauxite AI2O3 fused together with limestone at a temperature of 1,600 °C into clinker, which is then ground into powder. The chemical composition of high alumina cement is given below after Neville (1997) and Bukowski (1963) ... 

The first applications of glass fibres in concrete-like composites were published by Biryukovitch et al. (1965), who carried out tests on elements with high alumina cement. The paste made with that cement is characterized by pH from 11.8 up to 12.05 with total amount of alkalis from only 0.15% to 0.20% and during hydration calcium hydroxide does not appear. In the... 

Probably only large pores have an important detrimental influence on composite strength. Based on tests on high alumina cement specimens published by Murat and Bachiorrini (1987), it has been shown that a clear correlation existed only when porosity with pores larger than 1 pm was taken into acconnt. 

Most of the developments with FRC involve the use of ordinary Portland cements. However, high alumina cement, gypsum and a variety of special cements have also been used to produce FRC, generally to improve the durability of the composite, or to minimize chemical interactions between the fibres and the matrix. Recent developments also include specially formulated mortar and concrete matrices with controlled particle size distributions. 

An alternative approach, to be used either with E or AR glass fibres, was to modify the matrix in order to improve the resistance of the fibres, either by lowering the alkalinity level (e.g. silica fume additions high alumina cement) or by sealing the matrix (e.g. polymer modified cements). The long-term performance of the GRC composite is still the major criterion by which its quality is assessed, and considerable effort is continuously being made to improve the service life of such materials. These topics will be discussed in detail in Sections 8.4-8.6. The production methods and the properties of the composites will be dealt with in Section 8.3. 

CAC require large industrial facilities, similar to those used to make ordinary Portland cement. The raw materials for CAC are typically bauxite and limestone, which are ball-milled and mixed together to form a feed of appropriate composition, which is fed into rotary kilns to form a calcium aluminate clinker. The clinker is ball-milled to produce the cement. Analysis for composition and mineralogy at various stages of manufacture are essential to ensure a consistent product, see for example Chakraborty and Chattopadhyay [32] for a discussion of the bulk processing of high alumina CAC. 

Ellis, H. Fire barrier coating composition containing magnesium oxychlorides and high alumina calcium aluminate cements or magnesium oxysulphate, US Patent 4,572,862. 

Ca0.7Al203 cubic sp. gr. 2.68 (anhydrous), 2.73 (mono-hydrate) m.p. 1392°C thermal expansion (0-1200°C) 8.0 X 10-6. A. constituent of high-alumina hydraulic cement. This compound has not been prepared in a strictly anhydrous form when sorption of water has reached a max. the composition is i2CaO.7Al2O3.H2O. 

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