Good Report About Liquid And Plastic Limit Test

Purpose

The purpose of this lab was to determine liquid and plastic limits of the provided soil sample. Liquid limit is the moisture content of the soil at the point it changes from liquid to plastic state. In the experiment, liquid limit was the moisture content at the point at which the soil in moisture cup achieved a groove of 12.7mm after 25 blows. The other test done was plastic limit test. Plastic limit refers to the moisture content of the soil at the instance when the soil changes from plastic to semi-solid state. In the experiments, the plastic limit was determined at a point the soil of 3.18 mm diameter would be squeezed without crumbling.

Introduction

The report contains 3 main sections; the methodology, results and analysis and the discussion. The methodology section outlines the equipment and procedure used in the experiment. The result section contains tabulated experimental results, graphs, and the calculations. The last discussion section contains interpretations of results, responses, to questions and error analysis.

Equipment 1: Liquid Limit (LL)

Methodology
Balance Plastic squeeze bottle
Casagrande liquid limit device
Grooving tool
Moisture cans
Oven
Paper towels
Porcelain evaporating dish
Spatula
Procedure
The weights of the moisture cans were determined. 250 g of air dry soil was placed into evaporating dish. Water was added into the soil and mixed to form uniform paste. A portion of the paste was placed into brass cup of liquid limit device. The surface of the soil in the cup was smoothened such that the depth of the soil in the cup was 8mm. Grooving tool was used to make a groove along the center line of the soil. The liquid limit device was set at 2 revolutions per second. The soil paste was removed from the cup to the evaporating dish using after achieving a groove closer to 12.7mm at 30 blows. Water was added into the evaporating dish and the process repeated to achieve a groove closer to 12.7 mm at 23 and 18 blows. The three moisture can were placed in oven and dried.

Results

The liquid limit
Approximated from graph at 25 blows
26.1

Experiment 2: Liquid Limit

Methodology

Equipment

Balance sensitive
Ground glass plate
Moisture can
Plastic squeeze bottle with water
Porcelain evaporating dish
Spatula
Procedure
20 grams of air dry soil was placed into porcelain evaporating dish. Water was added into the soil and mixed thoroughly. The weight of the moisture can was measured and recorded as W1. Seven ellipsoidal-shaped soil masses were made by squeezing the soil using your fingers. One of the ellipsoidal-shaped soil masses was taken and rolled on glass plate using hands until the roll’s diameter was about 3.18mm.The roll was broken into pieces and squeezed to form ellipsoidal-shapes again. The other ellipsoidal-shaped soil masses were squeezed until they crumbled after attaining a diameter of about 3.18 mm. The crumbles were collected and put in moisture can covered with lid. The weight of the moisture can and its crumbles were measured and recorded as W2. The can and the crumbles were placed in the oven. After 24 hours, the can was removed and its weight and that of dry soil was measured.

Plastic Limit

PL=W2-W3W3-W1 X 100
39.9-38.938.9-32.7X 100
16.2X 100
16.2

Average Plastic Limit

16.2+19.62
17.9

Plasticity Index

PI=LL-PL
26.1-17.9
8.2

Clay mineral classification

The clay is Kaolinite. It has a liquid limit within the range of 20 to 40.

Flow index

w1 %-w2(%)LogN2-LogN1

This is the same as the gradient of moisture content versus no.of blows

The gradient was determined using the regression analysis in MS Excel 2007. The table below shows the result of the analysis.

The flow rate 0.28

Discussion
There are three group mineral classification of clay; Kaolinite, Illite and Montmorillonite. These classifications are based on liquid limit of the soil. The experimental results show that the liquid limit of the sample soil is 26.1%. This value is within the Kaolinite range of between 20% and 40%.
Errors in this experiment may have emanated from inaccuracies in taking measurements. The units involved were small (mm) and there is reasonable likelihood that the measurements were approximated and not exact.

Conclusion

The experiment was successful because the results of liquid and plastic limit test were determined. The result was used to classify the clay sample Kaolinite that has a liquid limit that ranges between 20% and 40%.