Liquid Limit Determination Lab
1. Pulverize a sufficient quantity of air-dried soil to obtain a 250g sample of
material passing No. 40 sieve. Be sure to break down all lumps.
2. Select and label 3 water content containers (with lids). Use the
following labeling system:
 Group # and can letter
 For example: 1a, 1b, 1c
 Record the weight of each container with the lid.
3. Adjust the height of drop of the liquid limit cup to exactly 10 mm.
4. Weigh out a 250g sample of soil into your evaporating dish.
5. Add a small amount of water to your 250g sample in order to achieve a
smooth creamy consistency (not too wet..like peanut butter). Mix until
uniform consistency is achieved. Be careful not to lose soil from dish
while mixing.
6. Remove cup from device.
7. Using spatula, fill bottom of cup with soil to a depth of 10 mm. The
depth of the tip of the grooving tool is 10 mm. Level off using spatula.
8. Using the grooving tool, cut a groove down the center of the soil sample.
9. Replace cup to device.
10. Turn crank while counting blows required to close the groove a total
length of ½ inch. Turn crank at a rate of 2 revolutions per second.
11. Record the number of blows.
12. Using the tip of the spatula, take a sample of soil perpendicular to the
closed part of the soil pat.
13. Place your sample from the tip of your spatula in a water content
container and apply lid. Be sure to use your containers in proper
sequence (a, b, c )
14. Return the remaining soil in the device cup back to the evaporating dish
sample. Clean device cup thoroughly.
15. Add 4-5 ml of water to dish and mix well.
16. Repeat steps 6 thru 15 until you have collected results from 3 tests that
yield a range of N between 15 and 40.
Ie. N = 25-35
N = 20-30
N = 15-25
Range of N should be at least 10 over three tests.
17. Leaving lid on, weigh the containers of soil and record.
18. Remove lids (apply to bottom & place in drying oven to determine water
content).
19. After determination of the water content for each container, plot the data
points from your tests on the sheet provided as follows:
y-axis = water content
x-axis = log of N=blows (semi-log scale)
20. Draw the best fit line through the plotted points.
21. The liquid limit corresponds to the water content of the soil at a blow
count of N=25 on the graph.
Number of Blows (N)