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Friday, December 6, 2019

HOW TO CALCULATE EFFICIENCY OF ADMIXTURE.

EFFICIENCY  OF ADMIXTURE

EFFICIENCY OF ADMIXTURE DETERMINE BY MARSH CONE TEST.

Marsh cone : Marsh cone is a brass cone with a stand which is used to measure efficiency of admixture as well as to determine optimum dose of an admixture. 

PROCEDURE IS GIVEN BELOW:
1) Take 2000gm of cement and 0.60 water cement ratio it will come 1200gm, mix both with a suitable mixture for uniform paste without lumps, seive it through 1.18mm seive to remove any lumps present in paste after mixing, pour the paste in the brass cone keep the aperture of marsh cone closed with one finger, after pouring 1 liter of paste in the cone remove finger and make the paste free from cone to jar which is placed under the Marsh cone,  simultaneously start the stop watch to determine the time taken by the paste come from cone to jar.

2) Repeat the procedure again with 1% of admixture dose and same quantity of water and determine the time taken by paste to come from cone to jar.

3) Repeat the procedure again with 1% admixture dose and with 1100 gm water and determine the time taken by paste for complete the test.

4) Repeat the test with 1000gm and 900 gm of water with 1% of admixture dose for both water content and determine the time.


LET

In first case when we not use admixture time is = 32 seconds

In second case when we use both adx. and water (1200gm) and 1% admixture time is =26 seconds

In third case time is = 28 seconds ( adx dose 1% and water 1100gm)

In fourth case time is = 30 seconds ( adx dose 1% and water 1000gm)

In fifth case time is = 32 seconds ( adx dose 1% and water is 900 gm)

THAN CALCULATION IS

       (1200 - 900)/1200 = 25%

SO EFFICIENCY OF ADMIXTURE IS   25% I.E
IT WILL REDUCE WATER UP TO 25% IN CONCRETE.

Aperture size not less than 6mm to avoid any blockage .


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