CEMENT
Now a days in construction industry's cement concrete is widely used as a construction material. In cement concrete cement is important ingredient in concrete cement is a binding material and it give the strength to concrete.
Cement is very fine material having adhesive and cohesive property which provide the binding material for other ingredient. It is obtained by burning the materials together of argillaceous (mainly alumina) and calcareous (mainly calcium carbonate and lime) to partly fusion at a high temperature about 1400 to 1500 degrees celsius. Joseph Aspdin manufactured cement and called as portland cement because when it is hardened it produced a material stone from quarries near portland in England.
The two calcareous and argillaceous materials used in manufacturing of cement. calcareous materials are lime, chalk, oyster shale and marl and argillaceous materials are clay, shale, slate, blast furnace slage.
Two process used in manufacturing of cement Dry and wet process. In dry process raw materials ground mixed and feed to rotary kiln in dry state. After grounted the material the gypsum is added 2 to 3% in rotary klin. The finished product of cement is finally baged in 50 kg per bag.
Chemical composition:
The raw materials used in manufacturing of cement is mainly lime, silica, alumina, lron oxide. These materials present various property of cement. These material when subjected to high clinkering temperature combine with each other to form complex compound. The identification of the major complex compound is largely based on R.H.Bogues work and hance these are called Bogues compound.
Chemistry of cement:
Portland cement consists of the following principal compound
(Figure: Represention of composition of portland cement)
Types of cements:
There are different types of cement as classified by Bureau of Indian standard (BIS) and it's IS Codes.
1. Ordinary portland cement
A. 33 Grade- IS : 269- 1989
B. 43 Grade- IS : 8112- 1989
C. 53 Grade - IS : 12269- 1987
2. Rapid hardening cement-
IS:8041- 1990
3. Fast Setting cement.
4. Low heat portland cement
IS:12600- 1989.
5. Portland slag cement
6. White portland cement.
7. Pozzolana portland cement
Uses
1. Ordinary Portland Cement
33 Grade : Using for PCC work, BBM and Plastering Work.
43 Grade : Useing for BBM & Plastering, Flooring, Waterproofing, Etc.
53 Grade : Using for RCC Concreting Work, Mass Concrete, Etc.
2. Rapid Hardening Cement
Using at under water construction.
3. Fast Setting Cement
Using for underground pile concreting.
4. Low Heat Portland Cement
Using for Mass Concreting, Machine Foundations, Furnace Foundation, etc.
5. Portland Slag Cement
Using for BBM and plaster work at low cost housing projects. as well as using in mass housing project.
6. White Portland Cement
We are known this cement as white cement, which is commonly using for joint filling in flooring, skirting, using at sanitory fitting work, etc.
7. Pozzolana Portland Cement (PPC)
This type of Cement is widely use in construction field, most of use in brick masonry, plastering amd waterproofing, flooring, etc.
Famous Brands of Cement
1. Ultra Tech Cement
2. ACC Cement
3. Shree Cement
4. Dalmia Cement
5. Ambuja Cement
6. Bharti Cement
7. Birla Cement
8. JK Cement
9. Bangur Cement
10. Choromandal Cement
All above types only OPC and PPC coment are using at all the project's and this cement is easily available in the market. but from last 1 years the difference in rate of OPC cement and PPC cement is just ₹5.00 therefore lot of consultant are refer OPC cement insted of PPC. use is same but difference in strengths. as well as another challanges need to face on site about the stock of both types of cement need to keep seperately, otherwise there are chance to do concreting by PPC cement and this type of cases happened many times, and this is very dangerous to concrete structure. so using of OPC is always better.
Important : Every Cement bag have 90 days validity, that means we can use this within 3 months from the date of manufacturing. Every lot we need to check the manufacturing date on the coment bag and verity it. after expiry date don't use any cement bags for structural work. which is very dangerous. Expired cement bags can be use at Labour camp PCC work, PCC work at temporary site office, etc.
As well as we should know about its Initial Setting time and Final setting time. Initial setting time of Cement is 30min and final setting time is 600 min i.e 10 hours.
After concreting we should keep this structure atleast 10hrs to achieve the Compressive strength.
Mixing Proportion is also very important part while getti g the knowledge about cement. in our Material Constant blog we had discussed about all the cement constant which are required for our work.
Team
CBEC India
(Article from Ms. Pranita)
