How To Check Quality Of Cement On Site?

Cement is a fine grey powder that, when mixed with water, sets to a hard mass. They possess both adhesive and cohesive properties. They adhere to building units such as bricks, stones, tiles, etc. because of which we are able to make walls and floors of very high strength.

They are considered hydraulic because they set and harden when mixed with water because of the chemical combination of the cement compounds with the water, which yields sub-microscopic crystals or a gel-like material with a high surface area.


There are generally two types of cement used on site. They are:

1.   Ordinary Portland cement (OPC): This is the most commonly used cement. This type of cement is manufactured in a powder form by mixing limestone and other raw materials which consists of argillaceous, calcareous, and gypsum. It has adequate resistance to dry shrinkage and cracking, but has less resistance to chemical attack.

It is admirably suitable for use in the place where there is a need for the fast construction and setting time, and where there is no exposure to sulphates in the soil or in the ground.

OPC of different grades attains their maximum strength after 28 days.

OPC is generally used and widely preferred for the construction of high-rise buildings, roads, dams, bridges, flyovers where high strength and fast setting are required.


2.   Portland pozzolana cement (PPC): It is an interground blended mixture of cement and pozzolana. Pozzolana is a natural or artificial material containing silica and alumina in a reactive form. These pozzolana materials include volcanic ash burnt clay, fly ash, opaline shales, etc.  

For the manufacture of PPC, about 25% of pozzolanic material is added to the OPC clinkers and gypsums and the mix is thoroughly ground.

They possess higher tensile strength and evolve less heat during the setting. They attain compressive strength with age, due to which they attain less compressive strength in early days.

They are widely used for hydraulic structures such as dams, sewage works, laying concrete underwater, etc. because they impart a higher degree of water-tightness and offer higher resistance to chemical attack and the action of seawater.


Generally, we use OPC for constructing our houses and other structures. OPC cement is available in the market in three grades. They are explained below:

1.   OPC-33 grade: For 33-grade cement, 33 means the compressive strength of cement should be 33 N/mm2 (Mpa) after 28 days. This grade of cement is not widely used and can only be recommended for low-strength works like plastering.


2.   OPC-43 grade: For 43-grade cement, 43 means the compressive strength of cement should be 43 N/mm2 (Mpa) after 28 days. They are generally used in non-RCC works, wall plastering, and pathways.



3.   OPC-53 grade: For 53-grade cement, 53 means the compressive strength of cement should be 53 N/mm2 (Mpa) after 28 days. This is a widely used grade of cement and is used in the RCC structures, buildings, pre–stressed concreting, heavy structures, etc.


Quality check of cement on site

1.   Manufacturing Date of cement or Packaging Date: There might not be physical changes in cement with time but the strength of cement reduces with age. This is because cement is in the form of powder and it has the property of absorbing moisture from the air quickly. When the cement bag absorbs the moisture from the air, the initial setting takes place and the cement will start to lose its strength gradually.

The cement should have to be used within the 3 months from its manufacturing date. This is because the cement used after 3 months of manufacturing date loses its strength by approximately 20-30%. They lose their strength by 30-40% after 6 months and by 40-50% after 12 months from the manufacturing or production date.


2.   Colour test:

The cement should have a uniform grey color with a light greenish shade. Cement color indicates the presence of excessive clay or lime.

3.   Lumps Test:

The sample of the cement must be free from the presence of lumps that are formed due to the absorption of moisture from the atmosphere by the cement. This process is termed hydration.

By inspection and supervision, we can conclude the presence of lumps and the cement bag with lumps should be rejected.


4.   Float Test:

Take a hand full of cement and throw it in water, if the cement floats on the surface of the water for some time before sinking, then it is a good quality cement. If the cement sinks immediately, then it is bad quality of cement. Also, if the cement floats on the surface of the water without sinking, then the cement is of bad quality.

5.   Temperature Test:

Cement tends to remain cool when it is in a bag. When we touch the cement from the bag, we feel the presence of cool (cold) in our hands.

 If the cement is cool inside the bag, then the cement is of good quality. If the cement is warm inside the bag, then the process of hydration has already taken place and cement is of bad quality.


6.   Rubbing Test for adulteration:

Adulteration is the process of making something poorer in quality by the addition of another substance.

 Take a pinch of cement and rub it within your fingers. If it gives a smooth feeling, then the cement is of good quality.

If it gives a Gritty or rough feeling, then there is an adulteration of silt or sand in the cement and is of bad quality.


7.   Setting Test:

Take about 100gm of cement and a small quantity of water and make a stiff paste of it. Then prepare a cement cake with sharp edges and put it on a glass plate and slowly take it underwater in a bucket.

Observing after 24 hours, the cake should remain in its original shape and it should attain some strength, for the cement to be of good quality, as shown in the figure below. The figure shown below is of good quality cement since there are edges.


8.   Strength Test:

Prepare a block of 25mm*25mm*200mm from the given sample of cement and immerse the block in water for curing for 7 days.

 Remove the block of cement from water and place it over the support that is 150mm apart and subject the block to a load of 340N (or 34kg weight). If the block does not show any failure, then the cement is of good quality.