ORDINARY PORTLAND CEMENT ( Physical and chemical Properties) - Printable Version

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ORDINARY PORTLAND CEMENT ( Physical and chemical Properties) - C M Dordi - 05-26-2022

ORDINARY PORTLAND CEMENT  
( Physical and chemical Properties )
Taken from : Ambuja Technical  Literature Series -2 

PART 1 - PHYSICAL PROPERTIES

1.0 INTRODUCTION
This two part publication is aimed at giving certain physical and Chemical properties of cement which can help · a
consumer to understand the significance of each property so that it can be used in a suitable manner.
This publication also gives guidance to the consumer on how to select this material to make the optimum use of the
same.
It must be understood that cement is a chemical and reacts when mixed with water. Cement particles develop a type
of growth on its surface which gradually spreads until it links up with the growth from the neighbouring cement particles.
It is this linking which results in progressive stiffening, hardening and strength development.
The chemical reaction continues in the presence of free water, moisture or humidity present within the mass or
outside. The mix becomes harder and stronger with age. This strength development is significant in the first
month but it does continue at a much slower rate for many years. This chemical reaction is called "hydration"
of cement and is accompanied by generation of heat which is called "heat of hydration" .

2.0 SELECTION OF CEMENT
Selection of Ordinary Portland Cement (OPC) depends on the consumer.
For a consumer it is important to look out for the following:

2.1 SOURCE I MANUFACTURER OR BRAND OF OPC
It is very important to procure OPC from a reliable source as there are good chances that the material could be adulterated. Lists of authorised retail shops are available with the OPC manufacturing companies in case a consumer desires to know from where to procure reliable quality of OPC in his area. 
It is also important to procure OPC of a reliable brand. Reliable brands are very consistent in their quality or in other words they market consistently good quality OPC which is more reliable in its performance and large variations in the properties can easily be ruled out.

2.2 GRADE OR STRENGTH OF OPC
The grade of OPC is clearly printed on the cement bags. 53 Grade cement is the highest grade of cement produced
in our country. The other lower grades available are either 43 grade or 33 grade.
The requirement of properties of all these cements are given in the following 
Indian Standards- IS : 12269- 1987 (53 grade), IS : 8112- 1989 (43 grade) and IS : 269-1989 (33 grade). The grade
number is the compressive strength in MPa {1 MPa = 10.21 kg/cm2) at 672 ± 4 hrs (28 days) of the cement when tested
in the manner described in IS : 4031. Consumers who desire to know more accurate strength results of their cement
can obtain test certificate from the manufacturer or can verify the grade, by testing the cement or arranging for a test,
in the manner described in Indian Standards.

2.3 WEEK OF MANUFACTURE
It is very important for the consumer to know the date of packing of the OPC. 
Fresher the cement, better is the performance. Cement being a hygroscopic substance, can lose
strength if not stored properly or if stored for long periods of time.
The manufacturers are required to state the week number and year of manufacture on the bag e.g. cement
manufactured on 03-02-96 will have 5/96 (week/year) stamped on the bag.

2.4 PHYSICAL EXAMINATION OF THE BAG
It is important for the consumer to also physically examine the bag. The net content of the bag should be 50 kg . Any tampering of the packing if observed should be reported to the shop--and manufacturer within 24 hours of delivery. If in doubt cement can be checked by
testing in either manufacturer's laboratory or in a laboratory of repute. 

2.5 TECHNICAL GUIDANCE I SERVICE
For optimum use of OPC and obtaining technical guidance the Manufacturer's
Technical Services Department is available. 
Prevention is better than cure. Technical Services are available to all consumers and it is therefore
advisable to take proper guidance on the use of mix proportion and other parameters before the work is
planned or executed rather than complaining after the work is executed by using improper mix or
by exercising inadequate control. 

2.6 SPECIFIC REQUIREMENTS
In case the structure requires certain specifications to be adopted then it is
advisable to hold proper discussions with the Engineers of Technical Services Department of the cement manufacturer
and ascertain more technical details about the OPC. 

3.0 PHYSICAL REQUIREMENTS
Generally, only the physical characteristics of cement are looked into by the consumer even through chemical
characteristics are of equal importance. The most important physical characteristic a consumer generally
looks for is the 28 days compressive 

for more detail download .... 
Taken from Ambuja Technical  Literature Series -2

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