GeoTech Lab Report Two

DEPARTMENT OFCIVIL & ENVIRONMENTAL ENGINEERING

LABORATORY REPORT COVER

Lab Report Two

CEGR 3258Geotechnical Engineering Laboratory

Submitted By: Date Performed:Sara Keranakis April 10, 2015

I, Sara Keranakis, have committed no violations of the UNC Charlotte Code of Student Academic Integrity in preparing and submitting this report.

Signature: Sara Keranakis Date: April 10, 2015

i

Executive Summary

This lab had to do with determining soil properties. The different soil properties where

found in several different ways throughout the lab times. Three tests were conducted on different

types of soils. The tests were done to determine engineering properties of soils that are vital to

building safety. The three labs were hydrometer analysis, consolidation testing, and compaction

testing.

The hydrometer test was done to find the particle grain distribution for soil too fine to be

determined by the sieve analysis. The soil was put through a test and the data found was plotted

to find the distribution curve. The soil that was tested had majority of its particles in the size

range of 0.03 mm. 48.4% of the particle fell in this range. This made the conclusion that the fine

soil was not well graded.

The consolidation testing took eleven days to collect all of the data. The data from the

different days had a different load rate for each day. This allowed a range of data to be calculated

against its self to find the slope of consolidation. Both the virgin curve and the recompression

curve were found in this lab. The virgin curve had a slope of 3.57 ×10−6 while the recompression

curve had the value of 2.28 ×10−6.

The final test was the compaction test. This test was done to find the optimum levels of

soil. The test results allowed for the optimum moisture content and for the maximum dry weight

to be calculated. The optimum moisture content was 22%. This amount of moisture content

resulted in a maximum dry weight of 11,900 KN

m3 .

The labs that were done in this report gave information that engineers can use in ensuring

that the soil is safe enough to be able to be built on.

ii

Table of Content

Title Page.....................................................................................................................................i

Executive Summary....................................................................................................................ii

Table of Contents........................................................................................................................iii

Introduction ................................................................................................................................1

Procedures...................................................................................................................................3

i. Hydrometer Analysis.................................................................................................................3

ii. Consolidation Test.....................................................................................................................3

iii. Compaction................................................................................................................................4

Results..........................................................................................................................................5



iii. Compaction................................................................................................................................7

Conclusions..................................................................................................................................8



iii. Compaction................................................................................................................................9

Reference………………………………………………………………………………………..10

Appendix......................................................................................................................................11

iii

Introduction

This lab report will go over three different types of labs done. These three labs

were done in a controlled environment under the supervision of a lab instructor. Each of the labs

tested different properties of soil. Most of the soil was either clay like soil of a fine-grained

sandy soil. The soils were provided by the instructor along with the appropriate materials needs

to conduct the labs. The three labs done were hydrometer analysis, consolidation, and

compaction.

The hydrometer test was the first test conducted in the series of labs. This testing

was done according to ASTM-D422. This test was done to determine the distribution of particle

sizes in the soil. The particles that are too fine to be determined by the sieve analysis are

analyzed by the hydrometer test. These particles are larger than 74 μm and retained on sieve 200

are used in this testing. This test gives engineers a better understand of the particle grain

distribution of the fine grains that cannot be determined by the sieve analysis.

The consolidation testing was the next series of test that were done in the lab. This

experiment was done according to ASTM-D2435. The test where done over a period of two

weeks. This gave the lab eleven days of data to compare for the compaction results. The result

analyzed the rate of compaction due to different loading pressures. The samples where doubly

drained and allowed water to escape from both ends of the sample. Consolidation involves the

transfer of stress from the pore water to the soil solids. The test are use to estimate the magnitude

of settlement of the soil before a structure is placed on top of it. This is important to engineers so

they can safety design around the load capacity of the ground surface.

1

The final test done in the lab was the compaction test. This lab used ASTM-D698

as its guidelines. The test compared the moisture content of the soil to the unit dry weight of its

self. This allowed for the relationship between the two to be shown and calculate the values for

maximum dry weight and optimum moisture content. This test is done to find the percent

compaction and moisture content needed in the fill material that may be used on site. This give

engineers the optimum conditions for fill material. This testing had two parts. One part was

finding the moisture content while the other was finding the units dry weight of the soil.

2

Procedures

The follow lab procedures all called for different soil samples that were collected and

supplied for the lab as a whole. Different groups did some of the tests and the data was combined

to compare results. Here are the methods that were used throughout the lab.

Hydrometer Analysis: (ASTM D422)

Materials- 50 grams of soil, stirring apparatus, hydrometer 151H, sedimentation cylinder,

thermometer, and constant-temperature room

1. Weigh out 50 grams of soil

2. Place sample in 250-ml beaker and cover with 125 ml of sodium hexametaphosphate

3. Stir until all soil is thoroughly wetted then disperse the sample using stirring apparatus

4. Transfer soil-water sample into glass sedimentation cylinder and add 1,000 ml of distilled

water

5. Invert cylinder and take hydrometer readings at the end of 2, 5,15, 30, 60 and 120 minutes.

6. To take hydrometer readings insert hydrometer about 20 to 25 seconds before reading is due

to approximately the depth it will have when the reading is taken

Consolidation Test : (ASTM D2435)

Materials- Load device, consolidometer, porous disks, deformation indicator, recess spacer

plate, balance, drying oven and miscellaneous equipment

1. Place consolidometer in the loading device and apply a seating load that results in a total

axial stress of about 5 kPa

3

2. Record initial deformation reading

3. Record deformation at time intervals 0.1, 0.25, 0.5, 1, 2, 4, 8, 15, 30 mins and 1, 2, 4, 8 and

24 hours

Compaction: (ASTM D698)

Materials- - Mold assembly, rammer, sample extruder, balance, drying oven, and mixing tools

1. Mix different amounts of water with soil sample to obtain different amounts of moisture

content

2. Record mass of mold then connect the mold to the base plate

3. Compact soil in three layers even layers applying 25 blows with the manual rammer

4. Remove any excess soil with a scraper and record the mass of the mold

5. Take small sample of soil and place in a can with know weight

6. Place can and soil in oven and allow to dry

7. Record final mass and calculate moisture content

4

Results

The results below include the data that was collected from the lab and all of the

calculations used to find the ending values.


Figure One: Hydrometer Analysis for Grain Distribution

Table One: Hydrometer Analysis Data

5


Figure Two: Consolidation Curve

Table Two: Consolidation Data

Figures Three through Thirteen in Appendix

6


Table Three: Compaction Data

Table Four: Moisture Content Data

Figure Fourteen: Compaction Data Curve

7

Conclusion and Analysis

The following section explains what the results that were calculated in the lab mean. This

section will discuss the data and describe what the data represents.


The hydrometer test allowed for the particle grain distribution to be found even though

the particles were smaller than the 200 sieve. The hydrometer showed that 48.40 percent of the

particles tested where 0.03 mm in size. With this number so close to half we can assume that this

is not a well graded fine soil. The soil had most of its size in the range of 0.03 mm to 0.02 mm.

These percent passing shown in table one do not completely add up to 100 therefore some error

had taken place in the collection of data and or the calculating of the values. Equations one, two

and three in the appendix show sample calculation on how the value of k, percent passing and

particle size (d) where found.


The raw data from figures three through thirteen where use to plot figure two. From

figure two equations four and five in the appendix where used to find the slope of the virgin

curve and the recompression curve. The slope of the virgin curve (C c) was found to be

3.57 ×10−6. The slope of the recompression curve (C r) was found to be 2.28 ×10−6. Many

calculations where used to find these values. Equations six and seven show a sample calculation

of how C v and e where found.

8


The compaction data found in tables three and four where plotted against each other. The

data created the compaction data curve. The curve gave the maximum dry weight and the

optimum moisture content. The trial numbers match directly to the can number respectively. The

varying moisture contents allowed for a curve with a peak value. The figure showed that the

maximum dry weight in around 11,900 KN

m3 and a optimum moisture content of 22 percent. A

sample calculation for moisture content is located in the appendix as equation eight.

9

References

ASTM D422 (2007). “Standard Test Method for Particle-Size Analysis of Soils.” American Society for

Testing and Materials, West Conshocken, PA

ASTM D698 (2012). “Standard Test Method for Laboratory Compaction Characteristic of Soil Using

Standard Effort.” American Society for Testing and Materials, West Conshocken, PA

ASTM D2435 (2010). “Standard Test Method for One-Dimensional Consolidation Properties of Soils

Using Incremental Loading.” American Society for Testing and Materials, West Conshocken,

PA

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Appendix

Equation one: 2.65−2.632.65−2.70

= 0.01328−k0.01348−0.01328

∴ k=0.0133

Equation Two:P=[ (100,00

M )∗G

G−G1]∗(R−G1)

Equation Three: D=k √ LT

Equation Four: C c=riserun

= 1.0781−1.0215,333.33−21,333.33

=3.57 × 10−6

Equation Five: C r=riserun

= 1.069−1.04771,333.33−10,666.66

=2.28 ×10−6

Equation Six: C v=

T50( HN )

2

t50

Equation Seven: e=e0−ei

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GeoTech Lab Report Two

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