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We tested 12 samples of soil each for both shear and tensile experiments.
Every two samples of soil had a different moisture level.
Preparations before tests:
Place newspapers on the worktable to avoid spillage onto the table itself.
Measure 1.5 g of sodium bicarbonate using an electronic balance.
Pour 1.5 g of sodium bicarbonate into the beaker.
Fill the beaker with water until it reaches the 400 ml mark.
Mix the two components thoroughly.
Cut the soil into twelve equal portions using the wire saw. (For shear)
Cut the soil into twelve equal portions using the wire saw. (For tensile)
Put different drops of sodium bicarbonate into each portion of soil.
Pour different numbers of tablespoons of vinegar into each portion of soil.
(Shear)
Measure the mass of each portion of soil on an electronic balance and note it down in Table 1 (see Section 2.4) and ensure all the masses are equal.
Increase the moisture level of two portions of soil by increasing the number of drops of sodium bicarbonate and vinegar by 1 for every two portions of the soil.
Measure the moisture level of the two portions of soils using the Rapitest 4-in-1 tester and note it down in Table 1.
Take one portion of soil as sample A and place it down in a container.
Ensure that the handheld shear vane’s reading is at 0.
Press the spikes of the bottom of the device into the soil surface.
Make sure your hand is not placed below the knob.
Start slowly rotating the device clockwise until the soil matrix fails.
Record the value on the scale to the nearest 0.01 kg/cm2.
Multiply the reading by the multiplier of the vane size.
Record the final value in unit kPa and note it down in Table 1 as Reading 1.
Repeat the experiment 1 more time to ensure the reliability of results for the other piece of soil with the same moisture level.
Repeat steps 2 to 12 for a total of 6 different moisture levels of soils.
Figure 1: Experimental setup for Shear Strength
(Tensile)
Measure the mass of each portion of soil on an electronic balance and note it down in Table 2 (see Section 2.4) and ensure all the masses are equal.
Change two portions of soil to a different moisture level with sodium bicarbonate and vinegar.
Measure the moisture level of the two portions of soils using the Rapitest 4-in-1 tester and note it down in Table 2.
Take one portion of soil as sample A and place it between two steel discs, one on the top and one on the bottom.
Apply vertical load slowly on the top disc until the soil reaches failure.
After that, use this formula to calculate the tensile strength:
where,
sigma t = simple tensile strength
P = applied load
b, H = dimensions found in Fig.2
a = radius of the punch
7. Repeat the experiment 1 more time to ensure the reliability of results for the other piece of soil with the same moisture level.
8. Repeat steps 2 to 7 for a total of 6 different moisture levels of soils.
Figure 2: Experimental setup for Tensile Strength
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