ALL YOU WANT TO KNOW ABOUT CEMENT AS CIVIL ENGINEER

ALL YOU WANT TO KNOW ABOUT CEMENT AS CIVIL ENGINEER 

CEMENT

Cement is the most important component of all the works that a bricklayer must carry out. It is manufactured by burning natural raw materials such as lime, silica, alumina, and iron oxide. The burning produces clinker and is crushed in a mill with a small amount of gypsum to produce cement.

Cement when in contact with water chemically reacts to form cement gel, a hydration product that gives it the strength and property of bonding to cement.

TYPES OF CEMENT

A) Ordinary  Portland  Cement  (OPC): Grade-33 This is the most common cement available in the market. It is used in most masonry work in India. However, many large plants in India do not produce this cement and prefer high-quality cement.

Most used as a construction material for building:

1.     Non-Specialized buildings

2.     Houses

3.     Bridges

4.     Pavements and so on.

It is also used for varied purposes including the making of concrete, mortars, etc.

This cement is available in three types of grades

1.     OPC grade 33

2.     OPC grade 43

3.     OPC grade 53

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Being an all-purpose cement with rapid set-up time and strength development, OPC grade cement has many applications in industrial and residential buildings, slabs and roofs and bridges.

B) Pozzolana Portland Cement: It is made by mixing 10-25% pozzolanic materials such as E. ash and burnt clay. It also works like slack cement. Initially, this cement is used as a plaster, which creates less cracks as the heat of hydration generated when it comes into contact with water is low.

Types Portland pozzolana cement

1.    PPC grade 43  

2.    PPC grade 53

The cement is available in any specific grades. It is finer and less dense than OPC. As it uses a lesser concentration of cement, it is cheaper and more environmentally friendly than OPC.

PPC is used in the construction of:

1.    Marine structures

2.    Masonry mortars

3.    Hydraulic structures

4.    Dykes

5.    Sewage pipes

6.    Dams, etc

There are many other special-purpose cement such as,

1.   Rapid hardening cement

2.   Low heat cement

3.   Sulfate resisting cement

4.   White cement

5.   Portland pozzolana cement

6.   Hydrophobic cement

7.   Coloured cement

8.   Waterproof portland cement

9.   Portland blast-furnace cement

10.       Air entraining cement

11.       High alumina cement

12.       Expansive cement

but are used under special requirements only.

NOTE:

Currently, many large cement factories produce good quantities of granulated blast furnace slag (GPF) cement and Pozzolana Portland cement, and OPC production is proportionally reduced. This cement can be used as a replacement for OPC for public construction work and for hollow and reinforced concrete. However, due to the delay in the growth of the initial resistances, curing must be carried out for a longer period of time and the removal of the formwork must extend to approximately 30% of the time specified for the OPC.

TESTING OF CEMENT

A) Laboratory Test: All cement is tested before being exported to the cement plant. Each bag of cement is I.S. The specifications for which it is manufactured, the quality of the cement, the week, month, year of manufacture and the name of the company producing the cement

If the cement is purchased directly from the cement plant, it comes with a test certificate. It is recommended to perform independent cement tests from a reputable test house for bulk purchase of cement. In its original packaging 1 intact bag cement is randomly collected and sent to the test house for analysis. Laboratory is required to test the parameters as indicated

B) Field Test:  - Field tests should be done by the Junior Engineer at the site, for every truckload of cement received at the site as under.

1)  The stitching of the bag should be intact and original.

2) Check the quality of the cement and make sure that the IS Specifications is in cement bag

3)  Check the date (w- is marked for a week, m- for month and y- for the year) of manufacture- It should be fresh and not older than 3 months. Older than six months is not to be used. No lumps should be present.

4)  Keeping the hand in a bag, the feel of the cement and the rubbing between the fingers should be soft and it should be cool.

5) When a pinch is dropped in water it should float first before sinking.

6)  Immerse a small cube made of cement paste in water and after 24 hours it should gain some strength and its edges should be intact.

7)  Weigh 5 bags and the average weight should be 50Kg.

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