Field tests for cement

• Following four field tests may be carried out to ascertain roughly the quality of cement

1. colour : colour of cement should be uniform i.e. grey colour  with a light greenish shade  
2. Physical Properties : cement should fell smooth when touched or rubbed in between gingers 

• if it is felt rough ,it indicates adulteration with sand 
• if hand is inserted in a beg or heap of cement , it should  feel cool and not warm 
• if small quantity of cement is thrown  in a bucket of water , it should sink and should not float on the surface 
• A thin paste of cement with water should feel sticky between the fingers 
• if the cement contains too much of pounded clay and silt as an adulterant , the paste will give an earthy smell 

       3 :Persence of lumps : cement should be free form any hard lumps . such lumps are formed by                  the absorption of moisture form the atmosphere 

            . Any bag of cement containing such lumps should be rejected .

        4: Strength : strength of cement can be roughly ascertained in the following ways 

     

        (a) Briquettes with a lean or weak mortar are made . Size of briquettes may be about 75 mm* 25               mm*12 mm .The proportion of cement and send may be 1:6 .The briquettes are immersed in               water for a period of 3 days. if cement is of sounds quality , such briquettes will not be                         broken easily and it will be difficult to convert them into powder form

        (b)  A block of cement 25 mm *25 mm and 200 mm long is prepared and it is immersed for 7                     day  in water , it is then placed on supports 150mm apart and it is loaded with a weight of                     340 N  . The block should not show signs of failure