How to check good cement on site

Cement is a binding material which bonds sands, aggregates with water in concrete.
         It is not easy to check all properties of cement on site but there exist some preliminary field test which can give us a rough idea about the quality of cement.

Date of Packing :-

         Several studies stated that as the strength of cement reduces as time goes on. As per IS specifications cement should be re-tested if it is stored more than 3 months in the mill.

Colour of cement :-

           The colour of cement should be uniform. An ideal colour of cement is gray with a light greenish shade. Cement colour gives an indication of excess clay or lime.

Check for lumps :-

           Lumps are formed due to presence of moisture in cement. Cement under goes a chemical reaction when it is reacted with the atmospheric moisture this process is termed as hydration.

Rubbing testing :-

            Take a pinch of cement rub within your fingers, it should feel smooth while rubbing. If is rough, it indicates that cement is mixed with sand.

Float test of cement :-

           Take a handful of cement and throw it in water, a good quality of cement should sink and should not float on water.

Hand Insertion :-

          Insert your hand into the cement bag. It must give you a cool feeling. It implies that the no hydration reaction taken place in cement bag.

Shape test of cement :-

         Cement is also named as hydraulic cement as it also sets under water. Take a 100g of cement and make a stiff paste by adding some water. Then prepare a cement cake with sharp edge and place it on a glass plate. Immerse this plate in the shape should not get disturbed while settling.

       A good cement should be able to set and attain strength in water.

Strength test :-

Make a block of cement 25mm×25mm and 200mm long. Immerse the block into the water for 7 days. Place the immersed block on supports 15000mm15000mm apart and then load with a weight of 340N. The block which is made of good cement should not show any sign of failure.

Specific gravity of cement :-

              Finding the specific gravity of cement is important. If cement is stored for more than 3 months a good cement should have specific gravity in between 3.1-3.6 g/cm3.