WHAT IS INITIAL AND FINAL SETTING TIME TEST

INITIAL AND FINAL SETTING TIME TEST OF FRESH CONCRETE

AIM:- To determine the initial and final setting time of cement as per IS 4031- 1988.

PRINCIPLE:-  When cement is mixed with water to make a soft paste, It becomes gradually less plastic and finally becomes hard mass. The time to reach this both stage is termed as setting time of cement.
The setting time is divided into two parts, namely initial setting time and final setting time.

APPARATUS AND MATERIALS:-

  1. The vicat apparatus
  2. Ordinary Portland cement
  3. Balance
  4. Stop watch
  5. Measuring cylinder


PROCEDURE:-

  • INITIAL SETTING TIME


  1. Take about 400 grams of cement.
  2. Add 0.85% of water and prepare the cement paste. P is the percentage of water for the standard consistency.
  3. Start the stopwatch when water is added to the cement to make a paste.
  4. Fill the cement paste into vicar mould within 3 to 5 mins.
  5. A needle of 1 sq.mm in cross sectional area and 50 mm long is attached and brought down to touch the surface of the paste and quickly released allowing it to sink into the cement paste by its own weight.
  6. In the beginning the needle will completely  pierce through the test block but after some time, when the paste starts losing its plasticity, the needle may penetrate only to a depth of 33 to 35 mm from the top of the cement paste.
  7. The period elapsing between the time when water is added to the cement to the time at which the needle penetrates the test block to a depth of 33 to 35 mm from the top of the surface is taken as initial setting time.
  • FINAL SETTING TIME
  1. Replace needle of the vicar apparatus by a circular attachment needle which has a needle projecting 0.5 mm from the circular cutting edge. The circular cutting edge has 5 mm diameter.
  2. Lower the attachment gently over the surface of the test block and observe the impression made by the circular cutting edge and the projected needle.
  3. The cement shall be considered as finally set when, upon lowering the attachment gently over the surface of the test block. The centre needle makes an impression while the circular cutting edge of the attachment fails to do so.
Note:- 
  • Ordinary Portland cement has initial sheeting time of 30 mins and final setting time of 600 mins.
  • Low heat cement has initial setting time of 60 mins and final setting time of 600 mins.

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