What Is Cement?
Important Point
- Evidence of the use of cement is believed to have been found in the hidden civilization of Mohenjodaro dating back 5000 years.
- The ancient Greeks used some form of mortar, but it remained for the Romans to develop and use cement.
- Cement is a substance that is used in a soft or plastic state, which then hardens to make things stick together.
- It can thus be regarded as a binder, glue, or adhesive, which in its hardened state binds aggregate particles to form a strong, rigid composite.
- Remember, the mixture of cement, sand, stone, and water is referred to as concrete.
- There are various substances that can act like cement, but we will be concentrating on the specific types used for concrete within the building and construction industry.
- Cement for construction is based on Portland cement and is supplied in powder form (either in bags or bulk) and, if mixed with water, will set and develop strength.
- Such cement is used extensively in most parts of the world because the raw materials are available in most regions. Also, these cement are relatively cheap and versatile as setting takes place at normal temperature and pressure, and can be used underwater and result in a strong and durable concrete.
Also, read: What Is Cement | Type of Cement
OPC Cement.
- OPC (Ordinary Portland Cement) is one of the most popular construction building materials used all across the globe.
- This name ‘Portland’ was given by the British cement manufacturer Joseph Aspdin at 1824 because of its strong resemblance to Portland Stone, a type of white-grey limestone found at this isle of Portland, Dorset at England.
- Joseph Aspdin is also credited to have patented this first true artificial cement, which he named as the Portland cement.
Also, read: What Is Soundness of Cement Test
Uses of Ordinary Portland Cement (OPC):
- It is used for general construction purposes where special properties aren’t required.
- This is normally used for the reinforced concrete buildings, pavements, bridges, and where soil conditions are normal.
- It is also used for most concrete masonry units and for all uses where the concrete isn’t subject to special sulfate hazard or where the heat generated by this hydration of cement isn’t objectionable.
- It has great resistance to shrinkage and cracking but has less resistance to chemical attacks.
Specifications OPC Cement
Parameter | OPC Cement | IS:12269 | |
Sp. Surface (m2/kg.) | 340 ± 10 | 225 m2/kg. minimum | |
Setting Time (in minutes)
|
Initial | 100 ± 5 | 30 minutes minimum |
Final | 150 ± 5 | 600 minutes maximum | |
Expansion
|
Le-Chatelier Expansion (in mm) | 1.5 mm max. | 10 mm maximum |
Autoclave Expansion (in %) | 0.17% | 0.8% maximum | |
Compressive Strength (MPa)
|
3 Days | 40 ± 2 | 27 MPa minimum |
7 Days | 50 ± 2 | 37 MPa minimum | |
28 Days | 61 ± 2 | 53 MPa minimum |
PPC Cement
- Portland-pozzolana cement (PPC) is produced by grinding together Portland cement clinker and artificial pozzolana (Fly ash) with this addition of gypsum or calcium sulfate.
- Fly ash is a very fine material produced as a residue precipitated electro-statically or mechanically from the exhaust gases of a coal-fired thermal power station.
- Generally, 15-25% fly ash is mixed and ground together with 65-75% Portland clinker and 3-6% gypsum
Also, read: What is Consistency of Cement
Uses of Portland Pozzolana Cement (PPC):
- This Cement is Flyash based cement recommended for brick masonry, plastering, tiling, and waterproofing work.
- In these works, strength isn’t the major criterion.
- PPC has an edge on OPC as PPC has a slower rate of the heat of hydration.
- Thereby PPC is prone to educe shrinkage & less cracks ), better workability, and finishing.
Specifications PPC Cement
Parameter | OPC Cement | Requirement as per lS1489 (Part-1) : 1991 | |
Sp. Surface (m2/kg.) | 340 ± 10 | 300 m2/kg. minimum | |
Setting Time (in minutes)
|
Initial | 160 ± 5 | 30 minutes minimum |
Final | 270 ± 5 | 600 minutes maximum | |
Expansion
|
Le-Chatelier Expansion (in mm) | 1.5 mm max. | 10 mm maximum |
Autoclave Expansion (in %) | 0.17% | 0.8% maximum | |
Compressive Strength (MPa)
|
3 Days | 72 ±1 | 16 MPa minimum |
7 Days | 168 ± 2 | 22 MPa minimum | |
28 Days | 672 ±4 | 33 MPa minimum |
Also, read: Difference Between M Sand Vs River Sand | What is M-Sand & River Sand
Difference Between OPC and PPC
Sr.NO. | OPC Cement | PPC Cement |
1 | Definition: A mixture of limestone and other raw materials like argillaceous, calcareous, gypsum is prepared and then grinded to prepare OPC. | Definition: PPC is prepared by adding Pozzolanic materials to OPC. So, the main components are OPC clinker, gypsum, and pozzolanic materials (15~35%), which include calcined clay, volcanic ash, fly ash, or silica fumes. |
2 | Strength: Initial strength is higher than PPC. | Strength: PPC has a higher strength than OPC over a longer period of time |
3 | Heat of hydration: Generates more heat than PPC in hydration reaction which makes it less suitable for mass casting. | Heat of hydration: It has a slow hydration process and thus generates less heat than OPC. |
4 | Durability: Less durable in aggressive weather. | Durability: More durable in aggressive weather. |
5 | Cost: Costlier than PPC. | Cost: Cheaper than OPC. |
6 | Environmental Impact: Emits CO2 during the manufacturing process. | Environmental Impact: It constitutes industrial and natural waste which makes it eco-friendly. |
7 | Application: It is suitable where fast construction is required but not suitable for mass concreting due to heat issue as mentioned above. | Application: It is suitable for all types of construction work. For example RCC casting of buildings, mass concreting for bridges and even plastering and other non-structural works. |
8 | Setting Time: Lower than PPC. Its initial setting time is 30 minutes and final setting time is 280 minutes. Its faster setting time helps faster construction. | Setting Time: Setting time of PPC us higher than OPC. Its initial setting time is 30 minutes and the final setting time is 600 minutes. Its slower setting time helps to get better finishing. |
9 | Fineness: OPC has finiteness of 225 sq.m/kg. It has lower fineness than PPC. So, it has higher permeability resulting lower durability. | Fineness: OPC has finiteness of 300 sq.m/kg. It has higher fineness than OPC. So, it has lower permeability resulting in higher durability. |
10 | Grades available: 33 Grade, 43 Grade, and 53 Grade OPC cement are available | Grades available: No specified grade of PPC cement is available. |
11 | Workability: Lower than PPC. | Workability: Higher than OPC. |
12 | Resistance against chemical attack: It has lower resistance against alkalis, sulphates, chlorides etc. | Resistance against chemical attack: It has higher resistance against alkalis, sulfates, chlorides, etc. |
PPC Cement Setting Time-
On the other hand, the final setting time of PPC is 600 minutes that is 25 days PPC cement prolongs the setting time of concrete and hence it helps in better finishing of concrete.
What Is Cement Made Of?
Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore.
PPC Concrete
PPC is a type of blended cement. It consists of 15-35% pozzolanic material, 4% gypsum and the rest is clinker. PPC as per BIS code is equivalent to that of 33 grade.
What Is Cement Used For?
Cement is mainly used as a binder in concrete, which is a basic material for all types of construction, including housing, roads, schools, hospitals, dams and ports, as well as for decorative applications (for patios, floors, staircases, driveways, pool decks) and items like tables, sculptures or bookcases.
OPC Vs PPC Cement Price
The cost of the products of PPC Cement varies between Rs 340 to Rs 370 for every bag from Jun 2021 to May 2022. The OPC cost is approximately 300 rupees for every bag and it is quite expensive in comparison to OPC.
Initial Setting Time of PPC Cement
PPC requires more time to set than OPC. It takes 30 minutes to set initially, and 600 minutes to set completely.
OPC Vs PPC Setting Time
OPC requires a minimum curing period of 7 days. When OPC is exposed to hot and dry weather conditions the minimum curing period required shall not be less than 10 days. Whereas PPC required a minimum curing period of 10 days.
OPC, PPC Cement Full Form
Ordinary Portland Cement (OPC) Portland Pozzolana Cement (PPC) Portland Slag Cement (PSC)
OPC Setting Time
Initial setting time shall not be less than 30 minutes and final setting time should not be more than 10 hours.
OPC and PPC Full Form
PPC cement full form is Portland Pozzolana Cement. OPC cement full form is Ordinary Portland Cement. Both PPC and OPC cement is used in construction.
Difference Between OPC and PPC Cement Class 12
PPC concrete has higher strength than OPC concrete over a longer period of time. Generates more heat than PPC in hydration reaction, making it less suitable for mass casting. It has a slow hydration process and thus generates less heat than OPC. OPC concrete is less durable in aggressive weather.
Setting Time of OPC and PPC Cement
The initial setting time of OPC and PPC is the same and is 30 minutes whereas the final setting time of OPC is 280 minutes which is 4.67 hours. Its setting time is less than PPC so it is recommended in the project where props are to be removed early.
Full Form of OPC and PPC Cement
Generally, Ordinary Portland cement (OPC) is used in factories, power plants, and in large construction slabs. Portland pozzolana cement (PPC) is used to construct houses, schools, and residential building slabs. PPC is cheaper than ordinary Portland cement.
Ultratech PPC Cement Curing Time
Cure the concrete for a minimum of 10 days in normal weather conditions,. During hot weather (greater than 40°C), cure the concrete for a minimum of 14 days.
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