TITLE: PROPERTIES OF SOIL

PRESENTED BY:AMIR RASOOL TANTRAY

UNDER THE GUIDANCE OF:ASSISTANT PROFFESSOR KAVYA P GOWDA,EPCET,BANGALORE

ABSTRACT

•Design of the various pavement layers is very much dependent on the strength of the sub grade soil over which they are going to be laid. •Sub grade strength is also depending on the basic properties of the soil. Sub grade strength is mostly expressed in terms of CBR (California Bearing Ratio).• Weaker sub grade essentially requires thicker layers whereas stronger sub grade goes well with thinner pavement layers. The pavement and the sub grade mutually must sustain the traffic volume .•The sub grade is always subjected to change in its moisture content due to rainfall, capillary action, overflow or rise of water table.• This project is an attempt to understand the basic properties of sub grade such as specific gravity, Atterberg limits ,particle size distribution, optimum moisture content , maximum dry density, UCC and permeability test.

INTRODUCTION• A pavement is a durable surface having materials laid down on an area subjected to sustain mainly the vehicular traffic, such as a road or highway.• A pavement is typically a structure of various layers resting over soil either in embankment or in cutting.• A pavement is classified in general in two categories, i.e. namely a flexible pavement and a rigid pavement. • Traditionally the design of either kind of pavement is based on the strength of the compacted soil in the pavement, called sub grade. • The design of the pavement layers laid over the sub grade soil starts off with the determination of sub grade strength and the traffic volume which is to be carried.• The design of pavement is very much dependent on the sub grade strength of soil. Design criteria mainly needs thickness of layers.• Weaker sub grade needs thicker layers whereas stronger sub grade needs thinner pavement layers.

ObjectivesTo increase the bearing capacity.To reduce permeability of soil.To design flexible pavement.Cost analysis.To reduce the thickness of pavement

TESTS AND METHODOLOGY

•GRAIN SIZE ANALYSIS: IS 2720(PART 4) 1985•SPECIFIC GRAVITY: IS 2720 (PART 3)1980•ATTERBERG LIMITS: IS 2720(PART 5)1985• MODIFIED COMPACTION TEST:IS 2720(PART 8)1983•UCC : IS 2720(PART 10)1991•PERMEABILITY: IS 2720(PART 17)1986•CBR: IS 2720(PART 16)1986

1) SIEVE ANALYSIS

Sieve analysis is the name given to the operation of dividing a sample of aggregate into various fractions each consisting of particles of the same size. The sieve analysis is conducted to determine the particle size distribution in a sample of aggregate, which we call gradation. The sieve analysis gives us a detailed idea regarding the type, consistency and components of the soil.From the graph Cu=D60/D10=8 & Cc = D30^2/ D10*D60 =2.3 2) ATTERBERG LIMITS

BRIEF STEPS INVOLVED IN THE EXPERIMENTS

.Plastic Limit: This limit lies between the plastic and semi-solid state of the soil. It is determined by rolling out a thread of the soil on a flat surface which is non-porous. It is the minimum water content at which the soil just begins to crumble while rolling into a thread of approximately 3mm diameter. Plastic limit is denoted by wP.

Liquid Limit:It is the water content of the soil between the liquid state and plastic state of the soil. It can be defined as the minimum water content at which the soil, though in liquid state, shows small shearing strength against flowing. It is measured by the Casagrande’s apparatus and is denoted by Wl. Liquid limit corresponding to25 blows =35%

3) Specific gravity

Specific gravity of a substance denotes the number of times that substance is heavier than water. In simpler words we can define it as the ratio between the mass of any substance of a definite volume divided by mass of equal volume of water. In case of soils, specific gravity is the number of times the soil solids are heavier than equal volume of water. Different types of soil have different specific gravities, general range for specific gravity of soils:

1 SAND 2.63 - 2.672 SILT 2.65 - 2.73 CLAY AND SILTY CLAY 2.67 - 2.94 ORGANIC SOILS <2.0

Specific Gravity Classification

TRIAL 1 2 3

NO OF BLOWS 17 35 30

Wt OF EMPTY CONTAINER 21.2 20 15.4

Wt OF CONTAINER+DRY SOIL 40 28 34.8

Wt OF CONTAINER +DRY SOIL 34.4 26 29.6

WATER CONTENT 42.4 33.3 36.6

BLOWS WC

17 42.4

35 33.3

30 36.6

LIQUID LIMIT READINGS

16 18 20 22 24 26 28 30 32 34 361

10

100 LIQUID LIMIT GRAPH

NO OF BLOWSLIQUID LIMT CORRESPONDING TO 25 BLOWS =35%

WAT

ER C

ON

TEN

T

4. Particle Size Distribution

•The distribution of particles of different sizes determines many physical properties of the soil such as its strength, permeability, density etc. •Particle size distribution is found out by two methods, first is sieve analysis and the other method is sedimentation analysis •Both are followed by plotting the results on a semi-log graph. The percentage finer N as the ordinate and the particle diameter i.e. sieve size as the abscissa on a logarithmic scale. •The curve generated from the result gives us an idea of the type and gradation of the soil.• If the curve is higher up or is more towards the left, it means that the soil has more representation from the finer particles; if it is towards the right, we can deduce that the soil has more of the coarse grained particles.• The soil may be of two types- well graded or poorly graded (uniformly graded). Well graded soils have particles from all the size ranges in a good amount.

sieve size(mm)

mass retained Retained %

cumulative wt. cumulative % % finer

4.75 0.00 0.00 0.00 0.00 100.00

2.36 40.20 8.00 40.20 8.00 92.00

1.18 84.06 16.74 124.26 24.74 75.26

0.6 90.20 17.96 214.46 42.70 57.30

0.3 106.40 21.19 320.86 63.89 36.11

0.15 108.80 21.66 429.66 85.56 14.44

0.075 59.40 11.83 489.06 97.38 2.62

sum 8.70 1.73 497.76 99.12 0.88

WET SIEVE ANALYSIS

0.010.11100.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

wet sieve analysis

sieve size(mm)

% fi

ner

4. Shear strength

Shearing stresses are induced in a loaded soil and when these stresses reach their limiting value, deformation starts in the soil which leads to failure of the soil mass. The shear strength of a soil is its resistance to the deformation caused by the shear stresses acting on the loaded soil. The shear strength of a soil is one of the most important characteristics. The experiment used to determine the strength is Unconfined Compression test.

ENGINEERING PROPERTIES OF SOIL

SOIL PROPERTIES VALUES

Specific gravity (Gs) 2.65Consistency limit

Liquid limit 43%PLASTIC LIMIT 21%

PLASTICITY INDEX 22USCS CLASSIFICATION MHGRAIN SIZE ANALYSIS

GRAVEL 0%SAND 0%SILT 86%

CLAY 14%

MODIFIED COMPACTION TEST

•This experiment gives a clear relationship between the dry density of the soil and the moisture content of the soil.• The experimental setup consists of (i) cylindrical metal mould (ii) detachable base plate, (iii) collar (iv) rammer (4.5KG) .• Compaction process helps in increasing the bulk density by driving out the air from the voids •The maximum dry density (MDD) is achieved when the soil is compacted at relatively high moisture content and almost all the air is driven out, this moisture content is called optimum moisture content (OMC).• After plotting the data from the experiment with water content as the abscissa and dry density as the ordinate, we can obtain the OMC and MDD

Unconfined compression test

•This experiment is used to determine the unconfined compressive strength of the soil sample which in turn is used to calculate the unconsolidated, undrained shear strength of unconfined soil. •The unconfined compressive strength (qu) is the compressive stress at which the unconfined cylindrical soil sample fails under simple compressive test. •The experimental setup constitutes of the compression device and dial gauges for load and deformation. •The load was taken for different readings of strain dial gauge starting from ε = 0.005 and increasing by 0.005 at each step. •The corrected cross-sectional area was calculated by dividing the area by (1- ε) and then the compressive stress for each step was calculated by dividing the load with the corrected area.

Empty wt of Mould (M1gms) 5576 5576 5576 5576 5576 5576Weight of mould + compacted soil(W2)gm 9073.4 9343.5 6563.8 9924.6 9763.5 9645.3

Weight of Compacted Soil (W3)gm 3497.4 3767.5 3987.8 4348.6 4187.5 4069.3

Bulk Density (M3/V)g/cm3) 1.58 1.7 1.8 1.96 1.89 1.84

Water Content (w)% 8 10 12 14 16 18

Dry Density (ρb/1+w)gm/cm3 1.46 1.54 1.6 1.72 1.63 1.56

WATER CONTENT DRY DENSITY8 1.46

10 1.5412 1.614 1.7216 1.6318 1.56

MODIFIED COMPACTION TEST

6 8 10 12 14 16 18 201.3

1.35

1.4

1.45

1.5

1.55

1.6

1.65

1.7

1.75

OMC CURVE

WATER CONTENTFROM THE GRAPH IT IS EVIDENT THAT

OMC=14%MDD=1.72 g/cc

DRY

DEN

SITY

DGR

(divisions) Deformation(mm) PRR (divisions) Load (KN)Corrected

Area (mm2) Strain Stress

0 0 0 0 0 0 0

50 0.5 2 0.07 9.677 0.0588 0.0007233

100 1 5 0.0175 9.734 0.1176 0.001797

150 105 9 0.0315 9.792 0.176 0.003217

200 2 10 0.035 9.831 0.235 0.00356

250 2.5 14 0.049 9.911 0.302 0.00492

300 3 14 0.049 9.972 0.383 0.00584

350 3.5 24 0.084 10.033 0.402 0.00612

400 4 27 0.0945 10.095 0.465 0.00784

450 4.5 29 0.1015 10.157 0.529 0.00902

500 5 31 0.1085 10.221 0.5882 0.0106

550 5.5 30 0.1 10.285 0.647 0.00972

AVERAGE UCS VALUE @ 0TH DAY

0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

0.002

0.004

0.006

0.008

0.01

0.012

UCS @0TH DAY (AVERAGE VALUE)

STRESSUCS=0.0192KN/M2

STRA

IN

DGR (divisions) Deformation(mm)

PRR (divisions) Load (KN)

Corrected Area (mm2) Strain Stress

0 0 0 0 0 0 0

50 0.5 18 0.063 9.67 0.0588 0.01256

100 1 25 0.0875 9.734 0.1176 0.0298

150 1.5 28 0.098 9.792 0.176 0.03489

200 2 33 0.1155 9.851 0.235 0.03668

250 2.5 37 0.1295 9.911 0.294 0.03789

300 3 35 0.147 9.972 0.353 0.03485

350 3.5 32 0.152 10.033 0.4109 0.03187

AVERAGE UCS VALUE @ 3RD DAY

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.450

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

UCS @ 3rd day (AVERAGE VALUE)

Strainucs=0.03755kn/m2

Stre

ss

Deformation(mm) PRR (divisions) Load (KN)Corrected Area

(mm2) StrainStress

(KN/M3)

0 0 0 0 0 0

0.5 7 0.025 9.677 0.0588 0.03

1 18 0.063 9.734 0.1176 0.07

1.5 23 0.08 9.792 0.146 0.08

2 26 0.091 9.851 0.235 0.09

2.5 26 0.091 9.911 0.276 0.0984

3 26 0.091 9.972 0.353 0.0921

3.5 24 0.091 10.033 0.3812 0.08

UCS @ 7TH DAY (AVERAGE VALUE)

0 0.1 0.2 0.3 0.4 0.5 0.60

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

UCS @7th day (AVERAGE VALUE)

StrainUCS =0.0756KN/M2

Stre

ss

References

1. S.K Khanna and C.E.G Justo, Highway engineering. 2. G.Venkatappa Rao, RS Sasidar, Solid Waste Management and Engineered Landfills 3. Hoover, J.M., Meoller, D.T., Pitt, J.M. Smith, S.G. and Wainaina, N.W. (1982) “Performance of randomly oriented fibre reinforced Roadways Soils”, Lowa DOT Project-HR-211, Department of Transportation, Highway Division, Lowa State University. 4. Orman, M.E. (1994) “Interface shear strength properties of roughened HDP Journal of Geotechnical Engineering, ASCE, 120(4), 758-761. 5. Rao, G.V. and Dutta, R.K. (2004) “Ground improvement with plastic waste “Proceeding, 5th International Conference on Ground Improvement Technique, Kaulalumpur, Malaysia, 321-328. 6. HMSO. (1952) “Soil Mechanics for Road Engineers” London 7. Madhavi Vedula, Pawan Nath G and Prof. B. P. Chandrashekar , NRRDA, New Delhi Critical review of innovative rural road construction techniques and their impacts.