Reference
IS-10050-1981-Method for determination of slake durability index of rocks.
Objective
This test is done to find out the resistance offered by a rock sample to weakening and disintegration when subjected to two standard cycles of drying and wetting in a slaking fluid usually water.
Apparatus used
|
NAME OF EQUIPMENT |
CAPACITY |
LEAST COUNT/ACCURACY |
|
Balance |
As per requirement |
0.01% of the sample |
|
Slake durability test apparatus |
Must give 20 rev/min. |
— |
|
Oven |
105±50C |
10C |
Sample preparation
Test sample consist of minimum of 10 rock lumps, each weighing 40 to 60 g to give a total sample weight of 400 to 600 g. Rocks lumps should be spherical and corners of rock lumps should be rounded off during preparation.
Procedure
1. Dry the sample to constant mass by placing it in oven, maintained at a temp of 105±50C. Place the sample in the drum of the machine and record the weight of sample plus drum as ‘A’.
2. Fit the lid with the drum; mount the drum in the trough.
3. Fill the trough with slaking fluid to a level 20 mm below the drum axis. Rotate the drum at 20 rev/min for a period of 10 minutes.
4. Remove the drum from trough and remove the lid from the drum.
5. Dry the drum plus retained portion of the sample in an oven maintained at a temp of 105±50C.
6. Record the weight of drum plus retained portion of the sample as ‘B’.
7. Repeat the steps from 2 to 5 for a further period of 10 minutes. Record the weight of drum plus retained portion of sample as ‘C’.
8. Clean the drum and record its weight as ‘D’.
Calculation
The slake durability index (2nd cycle) is calculated as percentage ratio of final to initial dry sample weight as follows.
Slake durability index (%), Id2 = ((C-D)/(A-D))*100
Report
The slake durability index is reported to the nearest 0.1%.