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Portland Cement is
the generic term for fine, gray or white powder manufactured using high
temperature to produce calcium silicates that, in the presence of water, will
undergo hydration producing a product that will bring aggregates together to
produce mortar, stucco or concrete.
Portland cement is hydraulic cement, which means that
it sets and hardens due to chemical reaction with water. It may be noted that Hydraulic cements can be either Portland
cement or Non Portland Cement.
Non Portland Cements: Cements other
than Portland cement are Non Portland
Cements.
During manufacture of these
cements comparatively less energy is used and less carbon dioxide is emitted.
Thus they have an inherently smaller
'carbon footprint' than most cements based on Portland cement clinker. In
principle, this makes such cements more sustainable and therefore potential
candidates to eventually replace Portland
cements in whole or in part.
However, its widespread use in
construction will depend crucially on the geographical/geological availability
of the raw materials used in their manufacture. By and large, the raw materials used to make non-Portland
cements are less abundant and less widely dispersed. Limestone, the
principal raw material in Portland cement clinker production is geologically
abundant and hence it forms the basis for the 'global binder' Portland Cement.
Irrespective of the cement
type, extensive research on long term performance will be required before
widespread acceptance of Non Portland Cement in general construction, or structural
applications, could be achieved.
However, there are a number of non-Portland cements that have established niche
markets, some examples of these are:
Calcium Aluminate Cement (High Alumina Cement ) used for refractory
purposes or its rapid hardening properties, Magnesium Oxychloride cement (Sorel cement) for flooring, Magnesium Phosphate Cement for rapid
repair of roads and airport runways , Geo-polymeric
cements, Supersulfated Cements,
Calcium Sulfoaluminate Cements etc.
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