Why Ordienary Cement Cement grades are 33 ,43 and 53?

33, 43 and 53 are 28 days mortar cube compressive strength results in N/sq mm (MPa) of cement tested at a proportion of 1:3 (1 part cement and 3 part standard sand. The strength depends on the fineness and chemical composition of the cement. Now days, 33 grade cement is discontinued. On testing cement of reputed brand, one can find an average strength of 52 and 58 MPa for 43 and 53 grade cement respectively. (against a required of 43 and 53 MPa). However OPC is almost not available in retail market and for procurement in a project, the requisition should be given well in advance. PPC is readily available.

Hi,
a question :

when a buyer is asking for OPC 42,5, is it possible to sell him OPC 43 indian Standard ?

Thanks a lot

Hi,
a question :

when a buyer is asking for OPC 42,5, is it possible to sell him OPC 43 indian Standard ?

Thanks a lot

Ordinary Portland cement  is produced by grinding Clinker with Gypsum. 33,43,53  is  minimum 28 days strength to be achived as per BIS for that particular grade. 

Ex: 33 denotes OPC 33 GRADE cement the strength of should not be less than 33 Mpa (330Kgs/cm2) Vice versa for 43 Grade OPC 43 Mpa and 53 Mpa for 53 Grade OPC

The grades are copied from british standard and rounded off to intergers. These are based 28 day compressive strength.

With all the Tech Details We Have Seen in Disscussion is Correct.But The Next part is that We Have to Judge the Grade of Cement Depending On Site & Type of Structure viewing Curing Process.If It is Raft or Pile Foundation we would Prefer 33 Grade As in foundation we do not have Sufficient Curing Process Or No Full Proof Controle.If Mass concreting is There Then we would use 33 Grade as heat of Hydration will be less in 33 Grade.Heigher Grade Requires More Curing So We will use it where we could Insure Proper Curing.Otherwise Crack will develope.In summerwe could use 33 grade & In Winter Or Rainning Season We could use 53 G.

The grades indicates the minimum compressive strength after 28 days  of the mortar cubes. ( Mortar cubes are casted with the cement to be tested for strength with the BIS approved Standard Sand with water as per consistency test)

for eg:- 33 grade indicates minimum 33 MPa or 330 Kg/ cm2  i.e. 100%strength achieved after  28 days . Similarly 43 & 53 grades can be defined.

 But today. The production of OPC is almost stoped maximum of cement companys in the country&manufacture PPC which is not early strength i.e not achieved 100% strength after 28 days.

The grades indicates the minimum compressive strength tested for 28 days of the mortar cubes ( Mortar cubes are casted with the cement to be tested for strength with the BIS approved Standard Sand)

for eg:- 33 grade indicates 33 MPa or 330 Kg/ cm2 is the minimum 28 days strength so on.

Ordinary Portland Cement in three different grades and qualities and these are:

OPC-53

OPC-43,

OPC-33

53 Grade OPC is a higher strength cement to meet the needs of the consumer for higher strength concrete. As per BIS requirements the minimum 28 days compressive strength of 53 Grade OPC should not be less than 53 MPa. For certain specialised works, such as pre-stressed concrete and certain items of pre-cast concrete requiring consistently high strength concrete, the use of 53 grade OPC is found very useful. 53 grade OPC produces higher-grade concrete at very economical cement content. In concrete mix design, for concrete M-20 and above grades a saving of 8 to 10 % of cement may be achieved with the use of 53 grade OPC.

53 Grade OPC can be used for the following applications.

    * RCC works(Preferably where grade of concrete is M-25 and above)

    * Pre-cast concrete items such as paving blocks, tiles building blocks etc.

    * Pre-stressed concrete components

    * Runways, concrete Roads, Bridges etc.

    * Runways, concrete Roads, Bridges etc.

The physical and chemical requirements of 53 Grade OPC as per BIS Requirement are given in Table below: 

Physical Characteristics of 53 Grade OPC (BIS Requirement)

Is Code Finene SS (sq.m/k g Min) Soundness by Setting Time Compressive Strength

Lechatlier (mm)max Auto clave Max (%) Initial (mts) min Final (mts) Max 1 day Min Mpa 3 day Min Mpa 7 day Min Mpa 28 day Min Mpa

(IS 12269- 1987) 225 10 0.8 30 600 NS 27 37 53

Chemical Characteristics of 53 Grade OPC (BIS Requirement)
 

Is Code Lime Saturation Factor Alumina Ration Min Insoluble MgO (%) Sulphuric Anhydride Loss ignition (%) Max

(IS 12269- 1987) 0.8 Min 1.02 Max 0.66 3 6 2.5% Max when C3A is 5 or less. 3% Max when C3A is greater than 4

OPC-43 GRADE

The 43 grade OPC is the most popular general-purpose cement in the country today. The production of 43 grade OPC is nearly 50% of the total production of cement in the country.

The 43 grade OPC can be used for following applications:

    * General Civil Engineering construction work

    * RCC works(preferably where grade of concrete is up to M-30)

    * Pre-cast items such as blocks, tiles, pipes etc

    * Asbestos products such as sheets and pipes

    * Non-structural works such as plastering, flooring etc.

The compressive strength of cement when tested as per IS code shall be minimum 43 MPa. The physical and chemical properties of this cement are given in the table:

Physical Characteristics of 43 Grade OPC (BIS Requirement)

Is Code Finene SS (sq.m/k g Min) Soundness by Setting Time Compressive Strength

Lechatlier (mm)max Auto clave Max (%) Initial (mts) min Final (mts) Max 1 day Min Mpa 3 day Min Mpa 7 day Min Mpa 28 day Min Mpa

(IS 8112- 1989) 225 10 0.8 30 600 Not specified 23 33 43

Chemical Characteristics of 43 Grade OPC (BIS Requirement)

Is Code Lime Saturation Factor Alumina Ration Min Insoluble MgO (%) Sulphuric Anhydride Loss ignition (%) Max

(IS 8112 - 1989) 0.66 Min 1.02 Max 0.66 3 6 2.5% Max when C3A is 5 or less. 3% Max when C3A is greater than 5 5

OPC-33 GRADE

This cement is used for general civil construction work under normal environmental conditions. The compressive strength of cement after 28 days test as per IS specification is 33 MPa. Due to low compressive strength, this cement is normally not used where high grade of concrete viz, M-20 and above is required. The availability of higher grades of OPC in the market are affecting the use of 33 grade OPC and now a days 43 grade OPC is normally used for general construction work instead of 33 grade OPC. More useful for mass concreting and plain cement concreting. Normally made to order basis. It can be used for plastering and single storeyed individual houses. The physical and chemical requirement as per BIS are given in table below:

Physical Characteristics of 33 Grade OPC (BIS Requirement)

Is Code Finene SS (sq.m/k g Min) Soundness by Setting Time Compressive Strength

Lechatlier (mm)max Auto clave Max (%) Initial (mts) min Final (mts) Max 1 day Min Mpa 3 day Min Mpa 7 day Min Mpa 28 day Min Mpa

(IS 269 - 1989) 225 10 0.8 30 600 NS 16 22 33

Chemical Characteristics of 33 Grade OPC (BIS Requirement)

Is Code Lime Saturation Factor Alumina Ration Min Insoluble MgO (%) Sulphuric Anhydride Loss ignition (%) Max

33 Grade OPC (IS 269-1989) 0.66 Min 1.02 Max 0.66 4 6 2.5% Max when C3A is 5 or less. 3% Max when C3A is greater than 5 5