Cement is the binding material having adhesive and cohesive properties. It sets and hardens by reacting with the water and binds with other materials to form water-resistance products. Different types of cement available in the market with different range of price, property and quality. Normally OPC and PPC are excessively used in construction fields. Besides these, there are so many special types of cement specially manufactured by focusing on one area like rapid hardening, quick setting, low heat, air entraining, colored cement, etc. Here we discuss about the suitable type of cement required for the building.
Suitable type of cement for building construction
During construction, many people are in confusion what types of cement is best. Which is the cement best for their dream house? Is there any wrong of using this or that types of cement? If you are constructing a building or you are an engineer and in confusion about it, then don’t worry, you will never in confusion about the suitable type of cement required for your building after reading this.
Let’s see some facts:
The density of cement may varies depending on the types but normally it is taken as 1440 kg/m3. The cement commercially found in market has weight of 50 kg and volume of 0.00347 m3. 1 m3 of cement is equal to 28.8 bags of cement. The other facts are discussed in table below:
Difference between OPC and PPC cement:
|Grade OPC 33, 43, 53, 43S, 53S||Not specified but equal to 33 grade|
|Prepared from argillaceous, calcareous, gypsum||Addition of pozzolana material(15-35%) to OPC|
|Higher initial strength||Similar strength after elapse of time|
|Less durable in aggressive weather||High durable|
|Expensive in cost||Cheaper than OPC|
|Suitable where fast construction is required. (Not suitable for mass concreting due to high heat of hydration.)||Suitable for all types of works. Eg. RCC casting of building, mass concreting for bridge and even plastering and other non-structural works|
|Initial setting time 30minutes||Initial setting time 30 minutes|
|Final setting time 280 minutes||Final setting time 600 minutes|
|Lower fineness(225kg/m2) – higher permeability – lower durability||High fineness(300kg/m2) – lower permeability – higher durability|
|Min. curing time 7-10 days||Min. curing time 10-14 days|
After reading this, may be you have got many doubt clear and you have decided to choose the suitable type of cement for you construction. Right?? If not, don’t worry I will illustrate further.
If you are constructing a residential building up to G+3, I will suggest you to use PPC cement because it will make economical but the cost of frame-work should also analysed. I know your intention is to make your building strong enough, not cheaper. But the use of PPC will give same strength as OPC after some elapse of time. Nowadays PPC is being excessively used in construction field.
If you want to complete your building in very short period of time, you shall go for OPC 43 grade. This is because it gives higher initial strength and we can remove form work in short period of time than PPC. But this makes your construction expensive for same ultimate strength as PPC. Some of you have thinking why 43 grade, right?? The reason is 43 grade OPC cement can give enough strength required for residential building and it is cheaper that 53 grade. It can produce concrete of grade up to M30 which is enough for residential house.
For plastering and finishing purposes, you can also use OPC 33 grade, it gives satisfactory result. And the cement grade 53 is not recommended for plastering as it is known to develop shrinkage, cracks due to its high strength and high heat of hydration.
OPC grade 53 is mostly used in major project like bridges, dams, high rise building, runways, etc. but mass concreting is not normally possible for OPC 53 grade due to its high heat of hydration. Special care should be taken to minimize the high heat of hydration or we have to go for the use of PPC for mass concreting.
Grade of cement:
Grade of cement means the compressive strength of the cement when tested after 28 days when tested as per indian standard under standard conditions. But the grade of cement does not indicates the compressive strength of concrete. For example: the 33 grade cement has compressive strength of 33 MPa when tested after 28 days. But OPC 33 may not suitable for concrete grade above M20.
The suitability of cement grade for concrete mix;
OPC 33 not suitable above M20
OPC 43 suitable up to M30
OPC 53 used only for concrete of grade M25 and above
But the grade of PPC is not specified and it can be used for any grade of concrete mix.
I hope you have got ideas to select suitable types of cement as your requirement after reading this. Now, you have to know, whether the cement bought is of good quality or not. Here are some of the field test that help you to know about the quality of cement.
Field tests of cement:
- Float test :
Take a handful cement from the new bag of cement and spread slowly on the bucket with clean water. The good quality of cement float for some period of time before sinking finally.
- Date of packing:
As the strength of cement reduces with time, the date of manufacture should be checked. The expiry date of cement is 6 month if it is properly stored. But it is not advisable to use cement of age more than 3 month.
- Smoothness test:
It should give a smooth feeling when cement is touched or rubbed in between the fingers. Rather than being smooth, if it feels like rough, it indicates adulteration with sand.
- Presence of lumps or loose material
If the cement bag contains lumps or loose material, it means it is not suitable for use. Such lumps are formed by absorption of moisture from the atmosphere.
The typical color of cement is grey with light greenish shade. The good quality of cement should have uniform color.
The good quality cement should feel cool when keeping hand inside cement bag. If hydration reaction takes place inside the bag, it will becomes warm.
After reading this whole text, if you are not satisfied or want to know more about the cement then you can view following indian codes if your country allows the use of IS codes:
Ordinary Portland Cement
Ordinary Portland Cement 33 Grade – IS 269:1989
Ordinary Portland Cement 43 Grade – IS 8112: 1989
Ordinary Portland Cement 53 Grade – IS 12269:1987
Portland Pozzolana Cement
IS 1489(Part I) 1991 (Fly ash based)
IS 1489(Part II) 1991 (Calcined based)