Soil and weathering lab

Niti Mankhemthong15/10/10

-Roundness?- Grain size?-Sorting?

Channel flow vs flow velocity vs sediment load & clasts

Speed water flow and Size???

12 2

Coarse-grained textures

Texture• Grain Sorting• Grain Rounding

Grain Size

Sorting or Graduation

Grain Roundness or Particle shape

Look at a descriptive handout

Observational data in terms of fluid velocity and grain size:

~ 100 g

Weight the dry clay (sieve no. 45 (~0.33 m))

Mixed with little water (2 spoon water )

1 cm height

TAP!! 25 TIMES

If you do not get

Weight the final wet samples

Add ½ spoon water each turn

Weight of wet sample and bowl Weight of day sample

Weight sample – dry sample

Water/dry sample

A B C = B – A D

E = C- D F %= (E/D) * 100 LL=F

COMPARE results among GROUP in class

Distilled water until the soil is at a consistency where it can be rolled withoutsticking to the hands.

Plastic limitThe plastic limit (PL) is the water content where soil starts to exhibit plastic behavior. A thread of soil is at its plastic limit when it is rolled to a diameter of 3 mm or begins to crumble. To improve consistency, a 3 mm diameter rod is often used to gauge the thickness of the thread when conducting the test.

around20 g

If you don’t get it!!

Then, weight the crumbles

Repeat all steps at least 3 times until get the sample at least 60 grams

In this experiment, let 1 student do 1 sample of 20 g. Thus, we will have 60 g sample for Plastic

limit calculation

Weight of wet sample and bag Weight of day sample

(from baking)

Weight sample – dry sample

Water/dry sample

A B C = B – A D

E = C- D F %= (E/D) * 100 PL=F

Solid behavior Plastic behavior Liquid behavior

Water content 0

Dry soil Wet soilLiquid limitPlastic limit

Max

Part 1Then, add more water in bowl until

Clay merge together ~0.5” wide STOP!!

Mix water with clay

Clay didn’t mergeAfter 25 taps

Part 2Roll more to dry clay until

Can roll clay into ½ diameter size

Mix too much water with clay

Cannot roll it anymore (break a part) STOP!!

Liquid limit determination

Plastic limit determination

SUMMARY of LL and PL concepts

Hint: We have clay and sand samples