FAQs for Engineers

1.    Is there any Indian Standard for blending materials like flyash & slag ?

The physical and chemical requirements for flyash and slag are governed by Bureau of Indian Standards .
The BIS codes for flyash and slag are IS 3812 ( Flyash for use as Pozzolona and admixture) and IS 12089 ( Granulated slag
The supporting codal specifications are as follows:
Methods of physical tests for hydraulic cement (Part I to XV) 4031 - 1986/89
Method of chemical analysis for Hydraulic cement 4032 - 1968
Methods of test for pozzolonic material 1727 - 1968
Fly ash for use as pozzolan and admixture 3812 - 1981
Granulated slag for the manufacture Of Portland slag cement 12089 - 1987

2.    What is PSC ( Portland Slag Cement ) ?

Portland slag cement is manufactured using OPC and granulated blast furnace slag, or in short slag. Slag is a byproduct obtained from steel plants. Slag is generated in molten form, which then is granulated through the process of quenching.

3.    What is PPC ( Portland Pozzolona Cement ) ?

PPC is manufactured either by intergrinding Portland Cement Clinker , flyash and gypsum to the required fineness or by blending ground OPC with fine flyash. Fly ash is a byproduct in coal based thermal plants .

4.    What are blended cements?

Cements that are derived out of blending complementary materials such as fly ash, slag, etc, with clinker and gypsum are termed as blended cements . Two types of blended cements are popularly manufactured in India – Portland Pozzolona Cement ( PPC) and Portland Slag Cement ( PSC) .

5.    On what basis are the different grades of OPC categorized?

The cement that gives a 28 day compressive strength of 33 MPa is known as 33 grade OPC , a cement with 28 day compressive strength of 43 MPa is 43 grade OPC , a cement with a 28 day compressive strength of 53 MPa is termed as 53 grade OPC.

6.    What are the different grades of cement available in our country ?

Ordinary Portland Cement ( OPC ) is categorized into three grades based on the 28 - day mortar strength – 33 grade , 43 grade and 53 grade .

7.    What are the various steps to be taken care in mix design calculations?

Before going for mix design calculations the characteristics of the materials those go into the concrete should be studied. For this the following are generally considered. Sieve analysis of fine and coarse aggregate Dry-roded unit weight of coarse aggregate Bulk specific gravity of the materials Absorption capacity of the materials After arriving to these values the other studies to be conducted are: Variation in the approximate mixing water requirement for the specified slump, air content grading of the available aggregate Relationship between strength and w/c for available combinations of cement and aggregate. Then all the above are to be assimilated to comply with the requirement of job specifications if any, viz., maximum w/c, minimum air content, minimum slump, maximum size of aggregate, and strength at 28-days.

8.    What are the types of cement commonly available in our Country ?

Portland Pozzolona Cement ( PPC ) is widely available . Other varieties of cement that are available are OPC – 43 grade , OPC – 53 grade and Portland Slag Cement

9.    Can you list the different types of cements ?

The various types of cements as per Bureau of Indian Standards :
Ordinary Portland Cement – 33 grade – IS 269
Ordinary Portland Cement - 43 grade – IS 8112
Ordinary Portland Cement – 53 grade – IS 12269
Rapid Hardening Portland Cement – IS 8041
Portland Slag Cement – IS 455
Portland Pozzolona Cement ( Fly ash based) – IS 1489 – Part 1
Portland Pozzolona Cement ( Calcined clay based) – IS 1489 – Part 2
Hydrophobic Cement – IS 8043
Low Heat Portland Cement – IS 12600
Sulphate resisting Portland Cement – IS 12330
Masonry Cement – IS 3466

10.    What is cement?

Cement is an adhesive material that is capable of bonding together fragments or particles of solid matter into a compact whole. Cement , from the construction point of view, is restricted to materials containing compounds of lime as their principal constituent .