Cement is very basic need of any construction work. There are around 19 different types of cements are available in market but Ordinary portland cement is the most widely used type of cement.
Here we will take a look at chemical composition of ordinary portland cement, properties of OPC, uses of OPC, types of OPC, advantages of OPC and disadvantages of OPC.
Cement is a very fine powdered material which on reaction with water forms a paste that has the properties of adhesion and cohesion and on hardening binds aggregates together to form a hard durable compact mass.
Function of cement is first to bind the sand and course aggregate together, to fill the voids between sand and course aggregate and to form compact mass.
Modern infrastructure totally based on concrete structures and it would have been impossible to build Burj Khalifa and Jinping-I Dam if cement was not there to prepare concrete. It will worth describing cement as the heart of Modern Infrastructure. But who invented the cement? and how? most of us don’t actually know the history of cement.
Although Joseph Aspdin filed the patent of preparation of ordinary portland cement on 21 October 1824 the basic knowledge every inventor used for preparation of a binding material was investigated by L.J. Vicat who prepared artificial hydraulic lime by calcinating mixture of clay and limestone.
However the name portland refer to natural stone from Portland, England which looked exactly similar to the set cement stone.
As the Use of ordinary portland cement in the construction industry increases rapidly the developed countries set down some standards on the use of cement. Germans set German standard specifications in 1877, British standard specifications set down in 1904 the same year when ASTM standards were specified.
To get all the properties of cement right the oxide composition of cement should be in proper proportions as shown in Table No.1.
The following table shows the chemical composition of cement
|Soda and Potash||Na2O + K2O||0.4-1.3%||1.0%|
We’ve already explained the Composition of Bogues Compounds with their properties and influence on strength.
The raw materials used for the manufacturing of cement are calcareous materials and argillaceous materials. Calcareous materials are limestone or chalk and argillaceous materials are shale or clay.
The manufacturing process consists of 4 steps or stages those are
Manufacturing can be done by any of the following two methods
Dry process is considered to be economical as compared to wet process because of less consumption of fuel.
The wet process has the advantages of low excavating cost, low grinding cost, and complete homogeneity in the slurry over the dry process.
Here are the properties of ordinary portland cement
ASTM classification of Ordinary portland cement is
Testing of cement is carried out to analyze presence of all the desirable properties in it. Testing of cement is classified under two categories depending on the extent of work and those are
Laboratory tests are conducted as per IS 4032:1985 and IS 4031(Part 1 to Part 15): 1988-99 and those tests are
Colour of ordinary portland cement is Greenish Grey.
Ordinary Portland Cement
OPC is short form of Ordinary Portland Cement.
830 to 1600 kg/cubic meter
Bulk density of ordinary portland cement varies between 830 to 1600 kg/cubic meter.
OPC 33 grade cement is ordinary portland cement with 33MPa as 28 days strength.