Compressive Strength of Cement (1:3)

Compressive Strength of object is defined as total load beared by object in compression just before it fails.
Compressive Strength of cement is used in Concrete Mix Design in order to reach the target strength of concrete.
The Compressive strength is calculated by 1: 3 cement sand mortar in shape of standardised cube.

Apparatus

• Universal testing machine
• cube moulds (side= 70.5 ± 1.27 mm)
• vibrating machine
• measuring cylinder
• trowel
• balance with weight box
  

Procedure

• Calculate the material required according to requirement. The proportion of cement sand ratio is 1: 3 which means 'x' gm of cement mixed with '4x' gm of sand . The water cement ratio is 0.4 means '0.4x of water in mix'.
• Firstly mix the dry material and then slowly add water until uniform colour of mixture is obtained. The mixing period should not be less than 3 mins. 
• Prepare the mould. Apply some oil inside to avoid sticking of mixture with cement. 
• Pour the mixture in mould and placed the mould on vibrating table. The period of vibration should be of 2 mins.
• Leave the mould for 24 hours at temperature of 27 ± 2°C. 
• Then remove the mould and immediately submerge it in clean water. Replace water every 7 days.
• Test the specimen on three side. Thus 3 cement moulds is required. The test is carried out on 3 and 7 days respectively.
• Take the average value of test.
  

Desired Result

The compressive strength of cube should not be less than 11.50 N per sq.mm and 17.50 N per sq.mm at end of 3 and 7 days respectively.