Portland cement is a finally ground material. It therefore readily absorbs moisture even from the atmosphere. It is essential to protect it from dampness during storage. Lack of proper care may cause setting of cement or reduction in its strength due to partial setting.
Following precautions must be takes in storing cement.
Of late, the consumer is confronted with a wide variety of cement in the market and has to make a choice. In the market, we have Ordinary Portland Cement ( OPC ) and the blended cement either as PPC or slag cement. Even in Ordinary Portland Cement, we have gradations as 43 grade and 53 grade.
Cement can be defined as the bonding material having cohesive & adhesive properties which makes it capable to unite the different construction materials and form the compacted assembly. Ordinary/Normal Portland cement is one of the most widely used types of Portland cement.
The chief chemical components of ordinary Portland cement are:
It is used for general construction purposes where special properties are not required. It is normally used for the reinforced concrete buildings, bridges, pavements, and where soil conditions are normal.
It is also used for most of concrete masonry units and for all uses where the concrete is not subject to special sulfate hazard or where the heat generated by the hydration of cement is not objectionable. It has great resistance to cracking and shrinkage but has less resistance to chemical attacks.
There are lots of environmental impacts of Cement on our ecology. One of the major problems is emission of CO2 from the Cement industry. It is found that world yearly 1.6 billion tons production of cement covers 7% of carbon dioxide's yearly production.
As CO2 is harmful for human health and also for the wild life. It causes many respiratory problems like asthma, bronchitis, and nasal infections.
The Portland Pozzolana Cement is a kind of Blended Cement which is produced by either intergrinding of OPC clinker along with gypsum and pozzolanic materials in certain proportions or grinding the OPC clinker, gypsum and Pozzolanic materials separately and thoroughly blending them in certain proportions.
The Portland Pozzolana Cement is ideally suited for the following construction. Hydraulic structures Mass concreting works Marine structures Masonry mortars and plastering under aggressive conditions. All other application where OPC is used.
Portland cement is composed of calcium silicates and aluminate and aluminoferrite It is obtained by blending predetermined proportions limestone clay and other minerals in small quantities which is pulverized and heated at high temperature - around 1500 deg centigrade to produce 'clinker'. The clinker is then ground with small quantities of gypsum to produce a fine powder called Ordinary Portland Cement (OPC). When mixed with water, sand and stone, it combines slowly with the water to form a hard mass called concrete.
Portland Pozzolana Cement (PPC) is obtained by either intergrinding a pozzolanic material with clinker and gypsum, or by blending ground pozzolana with Portland cement.
Nowadays good quality fly ash is available from Thermal Power Plants, which are processed and used in manufacturing of PPC. Higher durability of concrete structure due to less permeability of water.
This is a slag-based blended cement that imparts strength and durability to all structures. It is manufactured by blending and inter-grinding OPC clinker and granulated slag in suitable proportions as per our norms of consistent quality. PSC has many superior performance characteristics which give it certain extra advantages when compared to Ordinary Portland Cement
Compared to OPC, PSC imparts some important additional advantages