Design of Cement and Flyash Stabilized Permeable Base

8/4/2019 Design of Cement and Flyash Stabilized Permeable Base

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Permeability characteristicsof selected base coursemixes

Under the Guidance

of

Dr M.S AMARNATHProfessor

Faculty of Civil Engineering

Bangalore University

By

Charan Prasad M


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introduction

Pavement Structure

Components of Flexible Pavements

Surface course

Base course

Sub base course


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Detrimental effect of water inpavement layers

Stripping in HMA

Reduction of Granular Layer Stiffness & Strength

Loss of Subgrade Support

Debonding between Pavement Layers

Reduction in Pavement Service Life


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Cement-Treated Base

A intimate mixture ofaggregates withmeasured amounts of portland cement and

water that hardens after compaction andcuring to form a strong durable pavingmaterial


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Objectives of the present study

To carryout Modified Proctor Compactiontest and to determine the Optimummoisture content and maximum drydensity value for the permeable cement

treated base and permeable flyashtreated base samples.

To determine the CBR and Permeability

values for the permeable cementtreated base and permeable flyashtreated base samples.


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STRENGTH OF UNBOUNDAGGREGATE BASE COURSE

a. Ag g re g ate s with no fine s

b. Agg re g ate with sufficie nt fines

c. Agg re ga te with great amo unt offines


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Gradation selected for testing

Sieve Size, mm Percent Passing Median passingAASHTONo. 57 stone37.5 mm 100 100

25.0 mm 95-100 98

19.0 mm - -

12.5 mm 25-60 43

9.5 mm - -

4.75 mm 0-10 5

2.36 mm 0-5 3


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Permeable base mix preparation

Materials Used for Permeable Base Mix Design

Aggregate

Cement

Flyash


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Tests on Permeable base

Compaction Test

California Bearing Ratio Test

Permeability Test

Falling Head Permeability Test

Constant Head Permeability Test


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Permeability Test


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Selection of diameter of permeameter


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Fabrication of permeameter

PermeameterTop cap with water inlet and air nozzle

Permeameter mouldBase plate fitted with water outlet

Plates


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Test results

Modified Compaction Test OMC, MDD values of permeable base samples

GradationType

Modified Proctor Compaction test

Optimum Moisture Content, % Maximum Dry Density, kg/m3

2% Cement Treated 6.4 1890

3% Cement Treated 7.8 1950

2% Flyash Treated 7.2 1900

3% Flyash Treated 5.9 1760


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Dry Density v/s Moisture Content for prepared permeable base


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California Bearing Ratio TestLoad Penetration for Prepared Permeable Bases Mix Samples

Gradation 2% Cement Treated 3% Cement Treated 2% Flyash Treated 3% Flyash Treated

Penetration ,mm Load ,kg

0 0 0 0 0

0.5 185.6 211.2 89.6 57.6

1 428.8 505.6 166.4 198.4

1.5 659.2 812.8 275.2 300.8

2 921.6 1062.4 403.2 435.2

2.5 1107.2 1292.8 550.4 582.4

3 1497.6 1574.4 697.6 716.8

4 1945.6 2086.4 998.4 902.4

5 2233.6 2412.8 1318.4 1446.4

7.5 3155.2 3526.4 2470.4 2579.2

10 3955.2 4659.2 3641.6 3820.8

12.5 4998.4 5875.2 4704 4806.4


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Load Penetration curve for prepared permeable base


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CBR values of Permeable Base MixSamples

Gradation CBR at 2.5 mm (%) CBR at 5 mm (%)

2% Cement Treated 81 109

3% Cement Treated 94 117

2% Flyash Treated 40 64

3% Flyash Treated 43 70


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Permeability TestCONSTANT HEAD PERMEABILITY TEST

Hydraulic head ,h (cm) 63

Length of sample (L) (cm) 12.7

Cross-sectional area of sample(A) (cm2) 176.71

Time interval(t) (sec) 16

Quantity of flow(Q):

I test (ml) 106

II test (ml) 104

III test (ml) 106

Average (ml) 105

Coefficient of permeability (cm/sec) 7.5*10-3

Coefficient of permeability (m/day) 6.5


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Falling head permeability testArea of stand pipe (cm2) 12.56

Cross-sectional area of sample(A) (cm2) 176.71

Length of sample (L) (cm) 12.7

Initial head (H1) (cm) 75

Initial hydraulic head (h1) (cm) 164

Final head (H2) (cm) 55

Final hydraulic head (H2) (cm) 144

Time interval(sec):

I test (sec) 23

II test (sec) 22

III test (sec) 24

Average (sec) 23

Coefficient of permeability (cm/sec) 5.1*10-3

Coefficient of permeability (m/day) 4.4


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Conclusions The laboratory investigations of the prepared permeable mixes with

2% cement content and 2% flyash content showed a maximumdry density of 1890 kg/m3 and1760kg/m3 respectively indicating

that the cement treated permeable base is more stable due to itshigher dry density. Similar trend followed even at 3% cementtreated permeable base showing a higher maximum dry densityof 1950 kg/m3 to that of flyash treated permeable base with amaximum dry density of 1900 kg/m3.

The CBR values of the prepared permeable base with 2% cementwas 81% and 2% Flyash treated permeable base was 40% . Thusthe CBR values obtained shows a clear indication of higherstability with cement treatment rather than flyash treatment for apermeable base. Similar trend followed even in 3% cementtreated permeable base showing a higher CBR value of 94% tothat of flyash treated permeable base with a CBR value of 43% .

The permeability value of 3% cement permeable base was found tobe 6.5 m/day under constant head and 4.4m./day at falling headin permeability test.


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SCOPE FOR FURTHER STUDY

To design suitable gradation to act both asdrainage and sub base layer based on

performance based studies.


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THANK YOU

Design of Cement and Flyash Stabilized Permeable Base

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