m.e thesis presentation

STUDIES ON MECHANICAL AND DURABILITY PROPERTIES OF SELF COMPACTING CONCRETE

by

N. PRAKASH 200111824

M.E [Construction Engineering and Management ]

Under the guidance of Dr. P. DEVADAS MANOHARAN J. ANNIE PETERSupervisor Joint SupervisorProfessor Assistant DirectorDepartment of Civil Engineering Concrete Composites Laboratory Anna University Structural Engg. Research CentreChennai – 600 025 Chennai – 600 113

INTRODUCTIONINTRODUCTION· History· History

· Self Compacting Concrete (SCC)· Self Compacting Concrete (SCC)

· In fresh state guarantees high deformability and · In fresh state guarantees high deformability and high resistance to segregation.high resistance to segregation.

· In the setting stage, it guarantees low plastic · In the setting stage, it guarantees low plastic shrinkage and little settlement.shrinkage and little settlement.

· In the hardened state, it has a low permeability · In the hardened state, it has a low permeability and a high resistance to external agents and is more and a high resistance to external agents and is more durable. durable.

CHARACTERISTICS OF SELF COMPACTING CONCRETE

Flow ability

Absence of segregation

Ability to pass between reinforcement

Compaction under its own weight

Compatability of superplasticisers

Cement content

Water content

Form work should be preferably of controlled permeability

APPLICATIONS OF SELF COMPACTING CONCRETE

Bridges

Box culvert

Concrete filled steel Column

Tunnel

Dams

Concrete Products(Blocks, Culverts and Slabs)

Diaphragm Walls

Pipe Roof

Piles

Tank.

ADVANTAGES OF SELF COMPACTING CONCRETE Shorter construction period.

Holds good in densely reinforced structures

Elimination of noise due to vibration.

Saving in cost of compaction.

Highly durable concrete.

Less health-related problems for construction workers.

CHARACTERISTICS OF THE MATERIALS USED

Cement

53 grade OPC

Fine Aggregate

It is desirable to use a coarser variety of sand having a high fineness modulus.

Generally, fractions through 300 sieve or 150 sieve are to be kept low.

Coarse Aggregate

The coarse aggregate , an inert filler of the concrete, is the least porous component of concrete

It is preferred to use crushed aggregate than rounded aggregate

MINERAL ADMIXTURES

To increase the stability of the mixture To cut down the dosage of viscosity modifying

agent fine powders are used. Ennore field IV Fly Ash was used as mineral

admixtures

CHEMICAL ADMIXTURE Polycarboxylic ether based superplasticiser The dosage is optimized by Marsh cone test

WATER Potable water is used.

Sl. No

Properties Values

1 Specific gravity 3.15

2 Initial Setting time (minutes) 143

3 Final Setting time (minutes) 390

4 Standard Consistency (%) 31.50

5 Compressive Strength (N/ mm2)@ 3 days

26.50

@ 7 days 36.45

@ 28 days 54.45

Physical Properties of Cement

Properties of fine aggregate

Sl.No Property Values

1 Specific Gravity 2.53

2 Bulk Density(Kg/m3)

1600

3 Fineness modulus

2.83

Properties of Coarse aggregate (10 mm down)



2 Bulk Density (Kg/m3)

1605

3 Fineness modulus 6.24

Properties of Fly Ash

Properties of Superplasticiser

Sl.No

Property Values

1 Specific Gravity 1.22 - 1.25

2 Chloride content Nil

3 Approximate air entrainment

1 % at normal dosages

4 Operating temperature

Below 15 C



2 Bulk Density (Kg/m3)

825

DETAILS OF MIX PROPORTIONS

METHODS FOR ACHIEVING SELF-COMPACTING CONCRETE

1. Limited aggregate content

2. Low water binder ratio ( 0.9 – 1.0 on Volume basis)

3. Use of Superplasticisers and Viscosity modifying agent

Mortar (50 % of

Coarse aggregate

(50% of Solid Volume)

solid Volume)

Paste (60% of mortar volume)

Powder (50 -

55% paste volume)

Fine aggregate (40% Mortar

volume)

Water (45 -50% of paste

Volume)

Rational Mix design Method of SCC

Optimisation of Superplasticisers

The superplasticiser can be optimised for SCC by Marsh cone test.

The test consists of determining the time needed for a certain volume of paste to flow through the Marsh Cone for varying SP/ C ratio.

Aggregate proportion The minimum void content of the aggregate skeleton is determined

by filling a large container with dry mixes of varying sand/gravel ratios.

The Sand/ aggregate ratio was 1.128

Mortar

( 73.94 %

Coarse aggregate

(26.06 % of Solid

Volume)

of solid volume)

Paste (58.33 % of mortar

volume)

Powder (49.66 %

paste volume)

Fine aggregate (41.67 %

Mortar volume)

Water (50.33 % of

paste Volume)

MIX PROPORTION OF SCC

CEMENT = 490 Kg/m3

FLYASH = 160 Kg/m3

FINE AGGREGATE = 790 Kg/m3

COARSE AGGREGATE = 700 Kg/m3

WATER = 220 Kg/m3

SUPERPLASTICISER = 0.4 % of cement by weight

W/C = 0.449

W/B = 0.338

The mix proportion is 1: 1.215 : 1.077 : 0.338

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

% of Superplasticiser by weight of cement

Tim

e (s

econ

ds)

Slump Cone Test

PROPERTIES OF FRESH SCC

L Box Test

L Box Test

L BOX TEST

U Tube Test

V Funnel Test

Filling Ability Test

ACCEPTANCE AT SITE

Test results on fresh concrete properties

Sl.No

Fresh concrete test

Recommende

d Value

Observed

value

1 Slump flow 60 – 75 cm in 10 ± 3 seconds

70 cm in 5 seconds

50 cm in 5 ± 2 seconds

50 cm in 3 seconds

2 L box

20 cm 1.0 ± 0.5 seconds

1 second

40 cm 2.5 ± 0.5 seconds

2 seconds

h2 / h1 ratio

(h1,h2 Heights of

concrete - initial and final stage)

0.8 – 1.0

0.85

3 V Funnel 8 to 12 seconds 10 seconds

4 U Tube > 30 cm 33 cm

5 Filling ability A / (A+ B) value in percentage

90 – 100 %

90 %

DETAILS OF EXPERIMENTAL INVESTIGATIONS

MECHANICAL PROPERTIES OF SCC

Compressive strength

Split tensile Strength

Flexural strength

Modulus of elasticity

Pullout Test

DURABILITY RELATED PROPERTIES

Water Absorption test

Germann Water Permeability test

Rapid Chloride permeability test

Accelerated Carbonation test Accelerated Sulphate Resistance test

Charge Passed Chloride Permeability

> 4000 coulombs High

2000 to 4000 coulombs Moderate

1000 to 2000 coulombs Low

100 to 1000 coulombs Very Low

<100 coulombs Negligible

ASTM CLASSIFICATION FOR RCPT

18.01

37.37 48.98

75.01

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

AGE (Days)

Str

es

s(N

/Sq

mm

)

SCC

Compressive strength of SCC

1.83

6.23

5.495.37

0

1

2

3

4

5

6

7

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

AGE (Days)

Str

ess(

N/S

qm

m)

SCC

Split tensile Strength of SCC

0

5

10

15

20

25

30

35

0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012

STRAIN

ST

RE

SS

(N/m

m)

Modulus of Elasticity of SCC

Pullout test of SCC

TEST RESULTS AND DISCUSSIONS

RESULTS OF MECHANICAL PROPERTIES

Mechanical properties

Size of the Specimen

Age (Days) Values

Compressive

Strength (N/mm2)

150mm x 150 mm x 150 mm

1 18.01

3 37.37

7 48.98

28 75.01

Split tensile Strength(N/mm2)

100 mm x 200 mm

1 1.83

3 5.37

7 5.49

28 6.23

Flexural Strength (N/mm2)

100 mm x 100 mm x 500 mm

28 7.68

Modulus of Elasticity

(MPa)

150 mm x 300 mm

28 37500.00

Pullout Strength (N/ mm2) at

0.25 mm slip

150mm x 150 mm x 150 mm

28 18.62

Contd…

Mechanical properties

Size of the Specimen

Age (Days) Values

3.31

3.78

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Age (Days)

Wa

ter

Ab

so

rpti

on

(%

)

SCC

Water Absorption Test

0

50

100

150

200

250

300

350

400

0 1 2 3 4 5 6 7

Time ( hours)

Cu

rre

nt

(mA

) 7 days

28 days

Rapid chloride permeability test

RESULTS OF DURABILITY RELATED PROPERTIES Water Absorption Test

The % water absorbed at the age of 7 days and 28 days for self compacting concrete, the water absorption percentage was 3.78% and 3.31 % respectively.

Water Permeability test

The Coefficient of Concrete permeability of Self compacting concrete by using Germann Water Permeability Instrument at the age of 28 days was 0.721 x 10 – 11 m / s.

Rapid Chloride permeability test of SCC at 7 days

Time(Sec) Current (mA) Current (mA)

0 248 250

3600 346 347

7200 356 357

10800 360 361

14400 362 363

Coulombs 4921.2 4921.2

Average4921.2

Coulombs

Time (Sec) Current (mA) Current (mA) Current (mA)

0 61 83 84

3600 64 87 89

7200 67 92 93

10800 68 93 94

14400 68 93 94

18000 69 94 95

21600 70 95 96

Coulombs 1189.8 1627.2 1648.8

Average 1481.4 Coulombs

Rapid Chloride Permeability Test at 28 days

Carbonation Test

Specimen no Average Depth of carbonation

(mm)

1 0

2 0

3 0

Sl. No

Age

Days

Weight before

immersing in solution

(Kg)

Weight After

immersing in solution

(Kg)

Load (KN)

Compressive strength (N/mm2)

Average Compressive

strength (N/mm2)

1 30 2.4760 2.4770 749.80 74.98 74.71

2 30 2.4530 2.4565 748.00 74.80

3 30 2.4670 2.4705 743.50 74.35

Sulphate Resistance Test

Strength ratio

Strength ratio SCC HPC

t / c 8.3 % 7 %

b /c 10.3 % 11%

t / b 81.1% 63 %

Whereb = Flexure strength at 28 days

t = Tensile strength at 28 days

c = Compressive strength at 28 days

CONCLUSIONSCONCLUSIONS Self compacting concrete proportioned with available

materials to give a compressive strength of 70 MPa at 28 days.

The flexural and split tensile strength of SCC at 28 days were 7.68 MPa and 6.23 MPa respectively. The ratios t / c , b / c and t / b of M60 high performance concrete was given and the values were 0.11, 0.07 and 0.63 respectively while for SCC the corresponding ratios were 0.10 ,0.083 and 0.81 respectively.

The modulus of elasticity and bond strength of SCC at 28 days were 37500 MPa and 18.62 MPa respectively.

ConclusionsConclusions Self compacting concrete showed no signs of segregation

and bleeding. It also had self consolidating property.

The workability assessing tests such as slump flow, L - Box, V funnel, U tube and Filling ability could be relied on to assess the stability of the concrete mix.

Properties of SCC such as exceptionally good rheological properties and low water binder ratio resulted in dense microstructure. This was evident from the results of the accelerated chloride diffusion test.

Conclusions Conclusions Microstructural related properties such as water absorption ,water

permeability and chloride permeability confirmed the superior durability characterisation of SCC.

The strength and durability properties of self compacting concrete was similar to conventionally vibrated High Performance concrete as seen from the published literature.

For developing SCC technology, new testing and quality control

procedures are needed.

Possible deviation from IS specifications

A rational mix design method needs to be developed.

Specific stability evaluation methodology can be developed to guarantee the performance of SCC on site.

Binary and tertiary blended cements can be used for developing self compacting concrete.

Shrinkage and creep behaviour of SCC can be studied.

SCOPE FOR FUTURE WORK

THANK YOU

m.e thesis presentation

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