Table of Contents 1 Introduction ...................................................................................................................................................... 5 1.1

Background ............................................................................................................................. 5

1.2

Objective ................................................................................................................................. 5

1.3

Methodology........................................................................................................................... 5

1.4

Scope ....................................................................................................................................... 5

2 Literature Review .............................................................................................................................................. 6 2.1

Pavement ................................................................................................................................ 6

2.2

Rigid pavement ....................................................................................................................... 6

3 Experimental Studies ........................................................................................................................................ 7 3.1

Physical Properties of Aggregate ............................................................................................ 7

3.1.1

Sieve analysis of fine and coarse aggregates (IS2386:PART1-1963) ............................... 7

3.1.2

Specific gravity & Water absorption test (IS2386: Part 3-1963) ................................... 10

3.2

Physical Properties of Cement .............................................................................................. 10

3.2.1

Standard Consistency Test: ........................................................................................... 11

3.2.2

Initial and Final Settling time test: (IS:4031(Part 5)-1988)) .......................................... 11

3.3

Modifier - Glass Fibre ............................................................................................................ 12

3.3.1

Physical Properties ........................................................................................................ 13

3.3.2

Chemical Properties ...................................................................................................... 13

3.3.3

Length ........................................................................................................................... 13

3.3.4

Use in Concrete ............................................................................................................. 14

3.4

Mix Design of Concrete ......................................................................................................... 14

3.4.1

Objective ....................................................................................................................... 14

3.4.2

Design............................................................................................................................ 14

3.4.3

Test Data for Materials ................................................................................................. 15

3.4.4

Target Strength for Mix Proportioning ......................................................................... 15

3.4.5

Water-Cement Ratio ..................................................................................................... 15

3.4.6

Water Content .............................................................................................................. 16

3.4.7

Cement Content ............................................................................................................ 16

3.4.8

Coarse and Fine Aggregate Content ............................................................................. 16

3.4.9

Mix Calculation.............................................................................................................. 16

3.4.10

Mix Proportion .............................................................................................................. 17

B.Tech Project Report

3.4.11

Casting ........................................................................................................................... 17

3.4.12

Curing ............................................................................................................................ 18

3.5

Concrete Testing ................................................................................................................... 19

3.5.1

Compressive Strength ................................................................................................... 20

3.5.2

Modulus of Elasticity ..................................................................................................... 27

3.5.3

Poisson Ratio ................................................................................................................. 30

4 Rigid Pavement Design.................................................................................................................................... 33 4.1

Objective ............................................................................................................................... 33

4.2

Assumptions .......................................................................................................................... 33

4.2.1

Pavement type .............................................................................................................. 33

4.2.2

Design traffic ................................................................................................................. 33

4.2.3

Pavement structure assumptions ................................................................................. 34

4.2.4

Axle load spectrum ....................................................................................................... 34

4.3

Design.................................................................................................................................... 35

5 Results ............................................................................................................................................................. 37 5.1

Compressive Strength ........................................................................................................... 37

5.2

Modulus of Elasticity ............................................................................................................. 38

5.3

Poison’s Ratio ........................................................................................................................ 39

5.4

Pavement Design .................................................................................................................. 40

6 Conclusion and Discussion .............................................................................................................................. 41 7 References....................................................................................................................................................... 42

2


List of Figures Figure 2-1: Load transfer mechanism in flexible pavement ................................................................... 6 Figure 2-2 : Load transfer mechanism in Rigid pavement ...................................................................... 6 Figure 2-3 :Typical cross-section of Rigid pavement ............................................................................. 6 Figure 3-1: Sieve Analysis ...................................................................................................................... 12 Figure 3-2: Vicat Apparatus................................................................................................................... 12 Figure 3-3: Glass Fibre modifier ............................................................................................................ 12 Figure 3-4: RMC Machine mixing 1.5 % modified concrete .................................................................. 17 Figure 3-5: Casted Cubes and Cylinders ................................................................................................ 18 Figure 3-6: Cubes and Cylinder kept in curing tank to gain strength.................................................... 19 Figure 3-7 Input parameters require to fill before commencing the compressive test ....................... 20 Figure 3-8: Sample Result for compression test on cube ..................................................................... 20 Figure 3-9: Compressive test setup ...................................................................................................... 21 Figure 3-10: Failed cube ........................................................................................................................ 22 Figure 3-11 Compressive Strength of conventional concrete .............................................................. 23 Figure 3-12 Compressive Strength- 0.5% modified cube...................................................................... 24 Figure 3-13: Compressive Strength- 1.0% Modified cube .................................................................... 25 Figure 3-14: Compressive strength- 1.5% modified cube .................................................................... 26 Figure 3-15: Modulus of Elasticity setup............................................................................................... 27 Figure 3-16 Complete Loading Cycle..................................................................................................... 28 Figure 3-17: E value vs Concrete type ................................................................................................... 29 Figure 3-18: Poisson's Ratio test setup ................................................................................................. 30 Figure 3-19: Sample Stress vs strain graph in PR test ........................................................................... 31 Figure 3-20: Poisson's Ratio vs Concrete type graph ............................................................................ 32 Figure 4-1: Typical Cross section of a Rigid Pavement.......................................................................... 34 Figure 5-1:: %Compressive Strength vs Concrete type ......................................................................... 37 Figure 5-2: E value vs Concrete type graph .......................................................................................... 38 Figure 5-3: Poisson's ratio vs Concrete type graph............................................................................... 39 Figure 5-4: Minimum thickness curve ................................................................................................... 40

3


List of Tables Table 3-1: Sieve Analysis of Fine Aggregates .......................................................................................... 7 Table 3-2: Sieve Analysis of Coarse Aggregates ...................................................................................... 8 Table 3-3: Sieve Analysis % passing results............................................................................................. 8 Table 3-4: Fine Aggregates Gradation .................................................................................................... 9 Table 3-5: Coarse Aggregates Gradation ................................................................................................ 9 Table 3-6: Results of Specific Gravity and Water Absorption ............................................................... 10 Table 3-7: Consistency of Cement test ................................................................................................. 11 Table 3-8: Settling time test .................................................................................................................. 11 Table 3-9: Glass fibre sample lengths ................................................................................................... 13 Table 3-10: Mix Design- Stipulation for Proportioning ......................................................................... 14 Table 3-11: Mix Design- Test Data for Materials .................................................................................. 15 Table 3-12: Total Number of cubes and cylinders casted ..................................................................... 19 Table 3-13: Compressive Strength data - conventional cube ............................................................... 23 Table 3-14: Compressive strength data- 0.5% modified cube .............................................................. 24 Table 3-15:Compressive strength data- 1.0% modified cube ............................................................... 25 Table 3-16: Compressive strength data- 1.5% modified cube ............................................................. 26 Table 3-17: Elasticity Modulus test result as per the concrete type .................................................... 29 Table 3-18: Poisson's ratio test results ................................................................................................. 32 Table 4-1: Axle Load Spectrum ............................................................................................................. 34 Table 4-2: Input parameters for Concrete types .................................................................................. 36 Table 5-1: %Compressive Strength Results........................................................................................... 37 Table 5-2: Modulus of Elasticity result.................................................................................................. 38 Table 5-3: Poisson's ratio result ............................................................................................................ 39 Table 5-4: Safe thicknesses for each Concrete type ............................................................................. 40

4


1

Introduction

1.1

Background

The strength of concrete depends on the quality of ingredients, their relative quantities and the manner in which they are mixed, compacted and cured. It is possible to the produced concrete of different specifications for various purposes by suitably adjusting the proportion of cement, water, and aggregate. The use of admixture modifies the concrete suitably. Admixtures of specific types are used to modify the specific properties of concrete such as water reducing admixture reduces the water content while maintaining the same workability or increases the workability for the same water content. 1.2

1.3

Objective •

To determine the optimum dosage of glass fibre for modified concrete

•

To design the structural thickness of rigid pavement using properties of conventional and modified concrete and compare the results.

Methodology

Parameters, modulus of elasticity and poisons ratio are first determined for the conventional M40 concrete mix specimen, then these values are compared with modified concrete mix specimens which include glass fibre as admixture. Specimen used for testing both parameters is cylinder of standard size 150 mm diameter and 300 mm height as specified in European codes for testing modulus of elasticity and poisons ratio. 1.4

Scope

A evaluate the concrete properties using glass fibre and its effect on pavement thickness design.

5


2

Literature Review

2.1

Pavement

A highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade, whose primary function is to distribute the applied vehicle loads to the sub-grade. The pavements can be classified based on the structural performance into two types, flexible pavements and rigid pavements.

Flexible pavements will transmit wheel load stresses to the lower layers by grain-to-grain transfer through the points of contact in the granular structure. The wheel load acting on the pavement will be distributed to a wider area, and the stress decreases with the depth. Taking advantage of this stress distribution characteristic, flexible pavement normally has many layers. Figure 2-1: Load transfer mechanism in flexible pavement

Hence, the design of flexible pavement uses the concept of layered system. In rigid pavements, wheel loads are transferred to sub-grade soil by flexural strength of the pavement and the pavement acts like a rigid plate. 2.2

Rigid pavement

Rigid pavements have sufficient flexural strength to transmit the wheel load stresses to a wider area below. Rigid pavements are placed either directly on the prepared sub-grade or on a single layer of granular or stabilized material layer called base or sub-base course. In rigid pavement, load is distributed by the slab action, and the pavement behaves like an elastic plate resting on a viscous medium. Rigid pavements are Figure 2-2 : Load transfer mechanism in Rigid pavement constructed by Portland cement concrete (PCC) and should be analysed by plate theory instead of layer theory. Plate theory is a simplified version of layer theory that assumes the concrete slab as a medium thick plate which is plane before loading and remains plane after loading. Bending of the slab is due to wheel load and temperature variation and the resulting tensile and flexural stress.

Figure 2-3 :Typical cross-section of Rigid pavement

6


3 3.1

Experimental Studies Physical Properties of Aggregate

Aggregates are the inert materials mixed with binding material like cement, lime or mud in the preparation of mortar or concrete. Aggregates are necessary to avoid cracking, shrinkage and to improve work-ability. To reduce the cost factor, being cheaper than the cement and to reduce heat of hydration.  Coarse Aggregate which retain on ASTM sieve No. 4, or having a size greater than 4.75mm.  Fine Aggregate which pass through ASTM sieve No.4, or having a size less than 4.75mm but not less than 0.07mm.  Aggregates between 0.06mm and 0.002mm is classified as silt and particles smaller are called clay. 3.1.1 Sieve analysis of fine and coarse aggregates (IS2386:PART1-1963) This test method covers the determination of the particle size distribution of fine and coarse aggregates by sieving. This test method is used to determine the grading of materials proposed for use as aggregates or being used as aggregates. Accurate determination of materials finer than 75 micron (Sieve No 200) cannot be achieved by this test. Particle size distribution curve is obtained at the end of this test, which helps to determine the nominal size of aggregate of both coarse and fine. For all the design nominal size is taken as an average size of aggregates. Observation Fine aggregate Weight of sample taken = 1000 g Table 3-1: Sieve Analysis of Fine Aggregates

Sieve size (mm)

Weight of material retained(g)

%weight retained

% Cum. Weight retained

%Passing

10 4.75 02.36 1.18 0.60 0.30 0.15 0.075 Pan

00 23.5 37.9 83 116.4 304.2 331.7 99.9 21.3

00 2.308 3.723 8.154 11.435 29.885 32.586 9.814 2.095

00 2.308 6.032 14.186 25.621 55.506 88.093 97.092 100

100 97.691 93.967 85.813 74.378 44.493 11.902 2.092 00

7


Coarse aggregate Weight of sample taken = 3000 g

Table 3-2: Sieve Analysis of Coarse Aggregates

Sieve size (mm)

Weight of material retained (Kg)

%weight retained

% Cum. Weight retained

%Passing

20

1.280

43.54

43.54

56.46

16

0.860

29.25

72.79

27.21

12.5

0.420

14.28

87.07

12.93

10

0.260

8.84

95.91

4.09

4.75

0.100

3.40

99.31

0.69

Pan

0.020

0.69

100

0

Results : Table 3-3: Sieve Analysis % passing results

Fine Aggregate

Course Aggregate

Sieve size

%passed

Sieve size

%passed

10mm

100

20mm

56.46

4.75mm

97.69

16mm

27.21

2.36mm

93.96

12.5mm

12.93

1.18mm

85.81

10mm

4.09

600micron

74.37

4.75mm

0.69

300micron

44.49

Pan

0

150micron

11.9

75micron

2.09

Pan

0

 IS code recommendations IS 383-1970 Table 4 Fine Aggregates (Clause 4.3)

8


Table 3-4: Fine Aggregates Gradation

IS Sieve Designation

Grading Zone I

Grading Zone II

Grading Zone III

Grading Zone IV

10 mm

100

100

100

100

4.75 mm

90-100

90-100

90-100

95-100

2.36 mm

60-95

75-100

85-100

95-100

1.18 mm

30-70

55-90

75-100

90-100

600 micron

15-34

35-59

60-79

80-100

300 micron

5-20

8-30

12-40

15-50

150 micron

0-10

0-10

0-10

0-15

Table 2 Coarse Aggregates (Clause 4.1 and 4.2) – IS 383 - 1970 Table 3-5: Coarse Aggregates Gradation

IS Sieve Designation

80 mm 63 mm 40 mm

63 mm

40 mm

20 mm

16 mm

12.5 mm

10 mm

40 mm

20 mm

16 mm

12.5 mm

100

-

-

-

-

-

100

-

-

-

100

-

-

-

-

-

-

-

-

85 to 100 0 to 30

85 to 100 0 to 20

100

-

-

-

85 to 100

100

-

-

100

20 mm

0 to 5

16 mm

-

-

-

85 to 100

12.5 mm

-

-

-

-

0 to 20

0 to 30

10 mm

Percentage passing for graded aggregate of Nominal size

Percentage passing for single-sized aggregate of nominal size

0 to 5 0 to 5

4.75 mm

-

-

2.36 mm

-

-

0 to 5 0 to 5 -

-

95 to 100 30 to 70

100

-

-

95 to 100

100

100

-

-

-

90 to 100

-

85 to 100 0 to 45 0 to 10

100

-

-

-

85 to 100 0 to 20

10 to 35

25 to 55 0 to 10

30 to 70 0 to 10

90 to 100 40 to 85 0 to 10

-

0 to 5

-

-

-

0 to 5 -

9


Conclusion

Grading Zone of fine aggregate: Zone III Nominal Size of coarse aggregate: Not any size as per IS code recommendation 3.1.2 Specific gravity & Water absorption test (IS2386: Part 3-1963) Specific gravity: Specific Gravity is defined as ratio of weight of solid to the weight of an equal volume of gas free distilled water (no dissolved air/impurities) at a stated temperature. Water absorption: It is the ratio of weight of water absorbed to the weight of dry sample expressed as a percentage. It will not include the amount of water adhering to the surface of the particles It is used for the calculation of the volume occupied by the aggregates in various mixes and generally it ranges from 2.5 to 3. Water absorption value ranges from 0.1 – 2.0% for aggregate normally used in roads surfaces. Aggregates with water absorption up to 4.0% are acceptable in base coarse.

Table 3-6: Results of Specific Gravity and Water Absorption

Coarse aggregate

Fine aggregate

Specific gravity

2.98

2.54

Water absorption

2.11%

3.93%

3.2

Physical Properties of Cement

Cement is a binder, a substance used for construction that sets, hardens and adheres to other materials, binding them together. Cement is seldom used on its own, but rather to bind sand and gravel together. Cement is used with fine aggregate to produce mortar for masonry, or with sand and gravel aggregates to produce concrete. We used PPC cement of ultratech company whose price is 250 per bag(50kg).

10


3.2.1 Standard Consistency Test: Excessive addition of water in cement results an increase in Water cement ratio & ultimately cement loses its strength when it hardens. If Less water is added than required, Cement isn’t properly hydrated and results in loss of strength. The Standard or Normal consistency for Ordinary Portland cement varies between 25-35%. To explain in detail Let us assume a standard consistency is 30%. Take 400g of Cement for this quantity, Add 30% of Water. i.e., 120g of water content is added in cement to attain standard consistency. Result:

Table 3-7: Consistency of Cement test

Weight of sample(gm)

Water added(gm)

Plunger reading(mm)

Consistency of cement(%)

500 400

175 148

11 7

35 37

3.2.2 Initial and Final Settling time test: (IS:4031(Part 5)-1988)) Initial setting time: The time taken by cement to start losing its plasticity from the moment water is added. Final setting time: The time taken by cement to completely loose its plasticity. At this stage concrete starts hardening, Table 3-8: Settling time test

Sr. No.

Penetration from bottom(mm)

Time

01

0

00:13:46

02

0

00:27:17

03

0

00:54:12

Initial setting time

04

0

01:16:30

Between 2hour 34min

05

0

01:33:37

and 3 hour 3 min

06

0

01:55:17

07

3

02:34:56

08

8

03:03:46

09

Impression

03:08:02

11


10

Impression

03:22:20

11

Impression

04:28:48

Final setting time

12

No Impression

05:02:03

`5 hour 2 min

Figure 3-2: Vicat Apparatus

Figure 3-1: Sieve Analysis

3.3

Modifier - Glass Fibre

Figure 3-3: Glass Fibre modifier

12


3.3.1 Physical Properties : 6.3 – 6.9 gm/den : 2.5 gm/c.c : 3% : Bad : 0% : Excellent : Not good : White or colourless : Bright to light

Tenacity Density Elongation at Break Elasticity Moisture Regain Resiliency Ability to protest friction Colour Lustre 3.3.2 Chemical Properties

Acids Basic Effect of bleaching Organic Solvent Protection ability against mildew Protection ability against insects Effect of sunlight

: Hydrochloric and hot phosphoric acid causes harm : Good protection against alkali : Bleaching agent does not cause harm : Unchangeable : Does not affect : Does not affect : Sunlight does not change properties

3.3.3 Length Table 3-9: Glass fibre sample lengths

Sr. No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Length (in cm) 4.9 4.6 5.2 3.7 5 7.3 6.2 5.4 4.8 3.9 4.8 5.1 5.1 4.7 4.8 5.1 4.4 3.5 4.7

Sr. No 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Length (in cm) 4.6 5.1 4.9 4.7 4.7 4.6 4.6 4.1 4.9 5.1 5 4.8 4.9 5.2 4.7 4.9 4.7 4.6 4.8

13


20 21 22 23 24 25 Total Weight Per unit Average Length

5.2 4.7 4.1 4.8 4.8 4.9

45 46 47 48 49 50

5 3.8 4.1 5 4.9 4.9

: 101 mg : 2.02 mg : 4.806 cm

3.3.4 Use in Concrete As properties of Glass Fibre is what we require, we finally decided to adopt glass fibre as a modifier. Price of glass fibre is 275 rs per kg. After reading several papers on similar topic we came to conclusion that fibre should be added along with sand during casting process. The distribution of fibre must be uniform or else properties cannot be concluded insightfully. Glass fibre is added as a weight percentage of cement in all the case.

3.4

Mix Design of Concrete

3.4.1 Objective  To achieve the designed/ desired workability in the plastic stage.  To achieve the desired minimum strength in the hardened stage.  To achieve the desired durability in the given environment conditions.  To produce concrete as economically as possible. 3.4.2 Design Stipulations for Proportioning Table 3-10: Mix Design- Stipulation for Proportioning

Grade designation Type of cement Maximum nominal size of aggregate Minimum cement content Maximum water-cement ratio Workability

M40 PPC confirming to 20 mm 340 kg/m3 0.50 50 mm (slump)

14


Exposure condition Method of concrete placing Degree of supervision Type of aggregate Maximum cement content

Severe Pumping Good Crushed angular aggregate 450 kg/m3

3.4.3 Test Data for Materials Table3-11: Mix Design- Test Data for Materials

Cement used

PPC

Specific gravity of cement

3.00

Specific gravity Coarse aggregate Fine aggregate Water absorption Coarse aggregate Fine aggregate

2.11% 3.93%

Sieve analysis Coarse aggregate Fine aggregate

Confirming to grading Zone III of Table 4 of IS

2.98 2.54

3.4.4 Target Strength for Mix Proportioning f’ck where

=

fck + 1.65 s

f’ck = target average compressive strength at 28 days, fck = characteristic compressive strength at 28 days, and s = standard deviation.

From Table 1, IS 10262:2009, standard deviation, s =5 N/mm2 Therefore, target strength =40 + 1.65 x 5 =48.25 N/mm2

3.4.5 Water-Cement Ratio From Table 5 of IS 456, maximum water-cement ratio = 0.50. Based on experience, adopt water-cement ratio as 0.45 0.45 < 0.50, hence O.K.

15


3.4.6 Water Content From Table 2, IS 10262:2009, maximum water content for 20 mm aggregate =186 litre (for 25 to 50 mm slump range) Hence water content is 186 litres 3.4.7 Cement Content Water cement ratio = 0.45 186

Cement content = 0.45 = 413.33 kg/m3 From Table 5 of IS 456, minimum cement content for 'severe' exposure condition = 320 kg/m3 350 kg/m3 > 320 kg/m3.Hence, O.K.

3.4.8 Coarse and Fine Aggregate Content From Table 3 of IS 10262:2009, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone III) for water-cement ratio of 0.50 =0.60. In the present case water-cement ratio is 0.45. As the water-cement ratio is lower by 0.05 the proportion of volume of coarse aggregate is increased by 0.05. Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.45 = 0.63. For pump able concrete these values should be reduced by 10 per cent. Therefore, volume of coarse aggregate = 0.63 x 0.9 = 0.57. Volume of fine aggregate content =1 - 0.57 =0.43.

3.4.9 Mix Calculation Mix design calculations per unit volume of concrete is  Volume of concrete = 1 m3 

Mass of cement

1

Volume of cement = Specific gravity of cement × 1000 413.33

=

3

1

× 1000

=0.1378 m3 

Mass of water

186

=

 

1

Volume of water = Specific gravity of water × 1000

1

1

× 1000

=0.186 m3 Volume of all in aggregate = 1-(0.1378+0.186) = 0.6762 m3 Mass of coarse aggregate = 0.6762*0.415*2.5*1000 = 701.35 kg

16




Mass of fine aggregate = 0.676*0.585*2.98*1000 = 1178.47 kg

3.4.10 Mix Proportion Cement Water Fine aggregate Coarse aggregate Water-cement ratio

= 413.33 kg/m3 = 186 kg/m3 = 701.35 kg/m3 = 1178.47 kg/m3 = 0.45

3.4.11 Casting Cubes and cylinders are casted in RMC(Ready Mix Concrete) machine with arrangement as shown in figure below, RMC machine rotates at a particular RPM(Rotation per minute) speed. After mixing aggregate, sand, cement and water, the material is taken out into a big tray where it is mixed manually, and then cubes and cylinders are filled and transferred to vibration machine.

Figure 3-4: RMC Machine mixing 1.5 % modified concrete

17


Here as shown is figure below, the casted cubes and cylinders are kept for 24 hours in the mould and then they are removed and transferred to curing tank.

Figure 3-5: Casted Cubes and Cylinders

3.4.12 Curing All the casted cubes and cylinders are kept in the mould for 24 hours after they are casted. After 24 hours they are kept inside curing tank filled with water, the purpose of keeping concrete in curing tank is to gain strength. Cubes and cylinders gain strength from 0% at the 1st day to almost 86% at 28th day. Generally at 7th day the cube gains strength of around 70% and at 14 days around 90%. That’s the reason why curing is so important that all the big buildings and bridge’s pile are supplied with flow of water or using jute bag.

18


Figure 3-6: Cubes and Cylinder kept in curing tank to gain strength

3.5

Concrete Testing

Dimension of Cube(mm) = 150 *150*150 Dimension of Cylinder (mm) = 150 mm diameter 300 mm height Table3-12: Total Number of cubes and cylinders casted

S. No.

Cubes

Cylinders

Conventional

12

6

0.5 % Modified

6

4

1.0 % Modified

6

4

1.5 % Modified

7

4

Total

31

18

19


3.5.1 Compressive Strength Setup Input Parameters Dimensions : 150*150*150 mm Sensitivity : 15 KN Load Rate : 5150 N/s (Ref : IS 516-1959 Clause 5.5.1)

Figure 3-7 Input parameters require to fill before commencing the compressive test

Sample Result :



Compressive test setup

Figure 3-8: Sample Result for compression test on cube

20


The Screen shots shown above shows the input screen while doing compressive test and the below one shows the result displayed on the control’s screen, where load(KN) is shown on yaxis and time is shown on x-axis.



Specimen before test Specimen is put in the middle of a setup as shown below, there are plates kept below the cube specimen to support from below. As the test starts the bottom part starts moving upward, there is a limit of 5 cm which is the maximum amount of movement allowed.

.

Figure 3-9: Compressive test setup

21




Specimen after failure Machine stops compressing at a point where the load value on Y-Axis will go down up to the limit defined by sensitivity. The cracks can be seen on right downward side of a cube, that shows the cube has been failed.

Figure 3-10: Failed cube

Conventional Cubes Conventional cubes are the casted cubes without any addition of glass fibre in concrete mix as a conventional way of making concrete.

22


Table 3-13 Compressive Strength data - conventional cube

Day

Compressive Strength (Mpa)

% of Target Strength

07 - Day

32.835

68.41

14 - Day

43.96

91.58

28 - Day

47.44

98.83

Percentage Strength Achieved

Compressive Strength of Conventional Concrete 110.00 98.83 100.00

91.58

90.00 80.00 70.00

68.41

60.00 50.00 Series1

7 - Day 68.41

14 - Day

28 - Day

91.58

98.83

Days

Figure 3-11 Compressive Strength of conventional concrete

It was observed as shown in graph above that conventional concrete achieved strength of 98.83% that is 47.44 MPa at the end of 28 days, which is according to the expectations from a conventional concrete.

23


Modified Cubes These are the cubes which are casted with addition of glass fibre in the concrete mix. Glass fibre are added in three different proportions of 0.5, 1.0 & 1.5 % by weight of cement. Glass fibre is added during the casting process along with sand. 3.5.1.3.1 0.5 % Modified

Table 3-14 Compressive strength data- 0.5% modified cube

Day



07 – Day

21.61

45.02

14 – Day

31.71

66.05

28 – Day

44.20

92.08


Compressive Strength of 0.5 % modified Concrete 90.00

81.60

80.00 66.05

70.00 60.00 50.00

45.02

40.00 30.00 Series1

7 - Day

14 - Day

28 - Day

45.02

66.05

81.60

Days Figure 3-12: Compressive Strength- 0.5% modified cube

It is observed that 0.5% modified concrete achieved strength of 92.08% that is 44.2 MPa at the end of 28 days which is quite different than conventional, in case of conventional it generally lies on the range of 95% - 98%.

24


3.5.1.3.2 1.0% Modified

Table 3-15 Compressive strength data- 1.0% modified cube

Day



07 - Day

30.02

62.53

14 - Day

35.12

73.17

28 - Day

45.40

94.58


Compressive Strength of 1.0% modified Concrete 95.00 88.76

90.00 85.00 80.00 73.17

75.00 70.00 65.00

62.53

60.00 55.00 50.00 Series1

7 - Day

14 - Day

28 - Day

62.53

73.17

88.76

Days Figure 3-13: Compressive Strength- 1.0% Modified cube

It is observed that 1.0% modified concrete achieved strength of 94.58% that is 45.4 MPa at the end of 28 days which is quite close to conventional, in case of conventional it generally lies on the range of 95% - 98%.

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3.5.1.3.3 1.5 % Modified

Day



07 - Day

28.17

58.68

14 - Day

34.80

72.50

28 - Day

45.75

95.31

Table3-16: Compressive strength data- 1.5% modified cube


Compressive Strength of 1.5 % modified Concrete 120.00 95.31

100.00 80.00

72.50 58.68

60.00 40.00 20.00 0.00 Series1

7 - Day

14 - Day

28 - Day

58.68

72.50

95.31

Days

Figure 3-14: Compressive strength- 1.5% modified cube

It is observed that 1.5% modified concrete achieved strength of 95.31% that is 45.75 MPa at the end of 28 days which is quite similar to conventional, in case of conventional it generally lies on the range of 95% - 98%.

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3.5.2 Modulus of Elasticity Setup : As shown in figure below there is a gauge(transducer) which measures the vertical strain in cylinder when the load is applied. Gauge Length : 150 mm Channel Number of transducer : 5

Steps : 1. Mark line around the cylinder having offset of 7.5 cm from both sides 2. Make sure that the gauge key is locked and gauge is of length 150 mm 3. Put ribbon around the equipment into the space provided and hammer on both sides, upper and below such that nail gets stuck into concrete. 4. Start applying the load cycle after Insert transducer channel and unlocking the instrument.

Figure 3-15: Modulus of Elasticity setup

Standard recommendation ASTM C 469-02, cl. 3.2 recommends to apply cyclic loading to the specimen of following nature.

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First 3 cycle is of 1/6th load of ultimate failure load and preceding 4 cycle is of 1/3rd load of ultimate failure load. According to loading condition the stress-strain curve is obtained and the result is extracted from the Diagram tab where Elastic Modulus is displayed. Minimum load to be applied is 20 KN and not zero because specimen should be under pressure during the test as per code. Code recommends to apply loading to specimen at least 2 times to remove the voids and to consider result of 3rd test. And to take value of Elasticity modulus of last loading cycle.

Loading Cycle In all the following figures , the graph above shows the loading curve, where Y-axis represents load in kilo Newton(KN) and X-axis represents time in seconds. Graph below shows stress-strain relation where Y-axis shows stress in MPa and X-axis shows strain in microns.

Figure 3-16 Complete Loading Cycle

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Observed Values The table below shows the value of modulus of elasticity calculated at the endo f 14 and 28 days. It is observed that E-value increases as the fibre content increases. But the rate of increasing is decreasing. Table 3-17: Elasticity Modulus test result as per the concrete type

Elasticity Modulus Type Of Concrete 14

28

Conventional

29778.5

31050

0.50%

31351.5

33730.5

1.00%

31512

34990

1.50%

33561

35700

E-Modulus 37000

35700

36000

34990

35000

33730.5

34000

E value

33000 32000

33561 31050

31000

31351.5

31512

1

2

3

4

14 Day

29778.5

31351.5

31512

33561

28 Day

31050

33730.5

34990

35700

30000 29000

29778.5

28000 27000 26000

Type of Concrete 14 Day

28 Day

Figure 3-17: E value vs Concrete type

It is observed that Modulus of Elasticity value increases as the fibre content increases. From 300505 MPa of conventional to 35700 MPa of 1.5% modified concrete, an increase of 6.3% in value of E-Modulus.

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3.5.3 Poisson Ratio Setup As per ASTM C 469-02, cl. 3.2, target load is applicable within the customary working stress range (0 to 40 % of ultimate concrete strength). As per ASTM C 469-02, cl 6.4, test speeds for load channel and displacement channel are given as 4280 N/s and 20.83 μm/s respectively. There are two transducers for measuring strain in both direction, one for horizontal channel number 7 and other is for vertical channel number 6, Poisson’s ratio is the ratio of lateral strain and longitudinal strain. The gauge length of the setup is 200 mm. The setup of Poisson’s ratio test on cylinder is shown in figure below.

Figure 3-0-38: Poisson's Ratio test setup

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Steps   

     



First mark on the cylinder at 50 mm distance from top and bottom edges so that gauge length 200 mm is maintained. Unscrew all the bolts on the apparatus and fit it on the cylinder such that the top and bottom screws coincide with the marking. Tighten the top and bottom screws such that the cylinder and the rings are concentric and the spring on backside is perfectly vertical. Now keep the vertical transducer just touching and the horizontal transducer slightly compressed. Transducers measure the slightest relative movement and channels connecting transducers to the system will transmit this information to the software. Keep the middle ring screws just touching the cylinder. Channel 7 is connected to horizontal transducer and channel 6 to vertical transducer. The entire setup along with the cylinder is lifted up carefully and put in the CTM machine. In the software, channels 1, 6 and 7 are selected and test speed is provided for the channels Provide 40% of the ultimate breaking load of the cylinder as target load. Then start the pump and commence the test. A second window will appear which will show a graph of stress vs horizontal and vertical strains. The values of both the strains can be obtained from the graph A .txt file is generated having the data points. Uploading this file to another excel file provided by Controls will directly give the Poisson’s ratio value.

Figure 3-19: Sample Stress vs strain graph in PR test

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The figure above shows strain values measured by transducers, vertical axis represents stress value in MPa whereas horizontal axis represents strain value in micron. There are basically two type of strains horizontal that is radial and vertical that is axial. Generally strain value of axial is higher than radial, which justifies the value of poison’s ratio which should lie in the range of 0.1 to 0.2.

Observations Table3-18: Poisson's ratio test results

Poison's Ratio

Type Of Concrete

28

Conventional

0.19

0.50%

0.182

1.00%

0.14

1.50%

0.11

Poison's Ratio of 28 - Day concrete 0.21 0.19 0.182

Poison's Ratio

0.19 0.17 0.15

0.14

0.13 0.11 0.11 0.09 1

2

3

4

Concrete Type

Figure 3-200-4: Poisson's Ratio vs Concrete type graph

The poison’s ratio has an inverse relationship with Elasticity Modulus, which is exactly what we observed from the data above, the value of Poison’s ratio is continuously decreasing as the fibre content increases with whopping decrease of 42.1% from 0.19 of conventional to 0.11 of 1.5% modified concrete.

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4 4.1

Rigid Pavement Design Objective

The Objective is to design Rigid pavement for both conventional and modified concrete according to IRC 58-2015 with assumptions given as in section 8.2 4.2

Assumptions

All the design steps are according to Guidelines For the Design of Plain Jointed Rigid Pavements For Highways (IRC :58 – 2015). We have taken a sample road spectrum data of Gujarat state. The variables are Unity Weight, Elasticity Modulus, Poison’s Ratio and Compressive strength. 4.2.1 Pavement type  

4 lane divided carriageway with tied shoulders is to be designed with transverse joints having dowel bars. Lane width 3.5 m and transverse joint spacing 4.5 m are assumed.

4.2.2 Design traffic         

Design period is considered 30 years Total two-way commercial traffic in completion year is 6000 CVPD with equal traffic in each direction. Average annual growth rate of commercial vehicles is considered as 7.5%. Average number of axles per commercial vehicle is 2.35 Let proportion of vehicles with spacing between front and the first rear axle less than the spacing of transverse joints be 55% Assume 60% of vehicles travelling during night time. Let the proportions of front single, rear single, tandem and tridem axles be 45%, 15%, 25% and 15%, respectively. As we have selected data for Gujarat State, according to Table 1 of IRC : 582015 Clause 5.6, max. day-time Temperature Differential in slab, 0C (for bottom-up cracking) taken is 14.66 C Similarly night-time Temperature Differential in slab, 0C (for top-down cracking) = day-time diff/2 + 5 which is 12.33 C

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4.2.3 Pavement structure assumptions 

Cross section of pavement is assumed as belowPQC DLC/ Cement treated aggregates subbase Subgrade Figure 4-1: Typical Cross section of a Rigid Pavement

 

CBR value of sub-grade is assumed to be 8% Thickness of Granular sub base and Dry lean concrete sub base is assumed as 150 mm each.

4.2.4 Axle load spectrum The data shown below is of a particular road survey data ,where the data available is of Rear Single, Tandem and Tridem axle. Table 4-1: Axle Load Spectrum

REAR SINGLE AXLE

REAR TANDEM AXLE

REAR TRIDEM AXLE

Load Group (kN)

Frequency (%)

Load Group (kN)

Frequency (%)

Load Group (kN)

Frequency (%)

185-195

18.15

380 - 400

14.5

530-560

5.23

175-185

17.43

360 - 380

10.5

500-530

4.85

165-175

18.27

340 - 360

3.63

470-500

3.44

155-165

12.98

320 - 340

2.5

440-470

7.12

145-155

2.98

300 - 320

2.69

410-440

10.11

135-145

1.62

280 - 300

1.26

380-410

12.01

34


125-135

2.62

260 - 280

3.9

350-380

15.57

115-125

2.65

240 - 260

5.19

320-350

13.28

105-115

2.65

220 - 240

6.3

290-320

4.55

95-105

3.25

200 - 220

6.4

260-290

3.16

85-95

3.25

180 - 200

8.9

230-260

3.1

< 85

14.15

< 180

34.23

< 230

17.58

Total

100

4.3

100

100

Design

All the design steps are according to Guidelines For the Design of Plain Jointed Rigid Pavements For Highways (IRC:58 – 2015) published by Indian Roads Congress. And for which we have prepared a standard excel sheet where we need to input few parameters such as    

Unit Weight Flexural Strength Elasticity Modulus Poison’s Ratio

All the other parameter useful in design are already mentioned in assumptions. From all the experiments we did for compressive strength, Elasticity Modulus and poison’s ratio for all the modified concrete and conventional concrete, we obtained the following data which are of 28-days average values

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Table 4-2: Input parameters for Concrete types

Concrete Type

Unit Weight (kN/m3)

90 - Days Flexural Strength (Mpa)

Elasticity Modulus (MPa)

Poison's Ratio

Conventional

23.91

5.3

31050

0.19

0.50%

23.95

5.12

33730

0.182

1.00%

24.1

5.19

34990

0.14

1.50%

24.13

5.21

35700

0.11

At the end of Design Cumulative Fatigue Damage(CFD) value of both Bottom up cracking (BUC) and Top down cracking (TDC) is calculated if, CFD < 1 ; Design is Safe with current assumed thickness of pavement CFD >1 ; Design is not Safe with current assumed thickness of pavement, so increase the thickness.

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5 5.1

Results Compressive Strength Table 5-1: %Compressive Strength Results

Compressive Strength Type Of Concrete 7

14

28

Conventional

68.41

91.58

98.83

0.50%

45.02

66.05

92.08

1.00%

62.53

73.17

94.58

1.50%

58.68

72.50

95.31

Compressive Strength

% of target strength achieved

105.00 95.00 85.00 75.00 65.00 55.00 45.00 35.00 1

2

3

Type of Concrete Conventional

0.50%

1.00%

1.50%

Figure 5-1 %Compressive Strength vs Concrete type

It was observed that compressive strength of conventional was quite well achieved at the end of 28-days. For modified concrete it can be seen from graph above that as the fibre content increases the strength achieved is also increasing. But all the concrete type crossed the design strength of 40 MPa at the end of 28-days.

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5.2

Modulus of Elasticity Table 5-2: Modulus of Elasticity result

Elasticity Modulus Type Of Concrete 14

28

Conventional

29778.5

31050

0.50%

31351.5

33730.5

1.00%

31512

34990

1.50%

33561

35700

E value

E-Modulus 37000 36000 35000 34000 33000 32000 31000 30000 29000 28000 27000 26000

34990

35700

33730.5 33561

31050 31351.5

31512

1

2

3

4

14 Day

29778.5

31351.5

31512

33561

28 Day

31050

33730.5

34990

35700

29778.5

Type of Concrete 14 Day

28 Day

Figure 5-2: E value vs Concrete type graph

It is observed that Modulus of Elasticity value increases as the fibre content increases. From 300505 MPa of conventional to 35700 MPa of 1.5% modified concrete, an increase of 6.3% in value of E-Modulus. The value of E-Modulus ranges around 30000 MPs for normal controlled concrete, but here because of fibre it is been improves, which was exactly as expected.

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Poison’s Ratio

5.3

Table 5-3: Poisson's ratio result

Type Of Concrete

Poison's Ratio of 28 Days

Conventional

0.19

0.50%

0.182

1.00%

0.14

1.50%

0.11

Poison's Ratio of 28 - Day concrete 0.21 0.19 0.182

Poison's Ratio

0.19 0.17 0.15

0.14

0.13 0.11 0.11 0.09 1

2

3

4

Concrete Type Figure 5-3: Poisson's ratio vs Concrete type graph

The poison’s ratio have an inverse relationship with Elasticity Modulus, which is exactly what we observed from the data above, the value of Poison’s ratio is continuously decreasing as the fibre content increases. There was a slight decrease from conventional to 0.5% but a great steep from 0.5% to 1.0% and then 1.0% to 1.5%, with whopping decrease of 42.1% from 0.19 of conventional to 0.11 of 1.5% modified concrete.

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5.4

Pavement Design

In rigid pavement design according to IRC : 58-2015 , using try and error method we obtained the following values of thickness which is minimum for that particular type of concrete. If thickness is further decreased then the overall value of cumulative fatigue damage (CFD) will be more than one making design unsafe for the assumed traffic and pavement condition. Table 5-4: Safe thicknesses for each Concrete type

Concrete Type

Conventional

0.50%

1.00%

1.50%

Thickness (m)

0.2554

0.2525

0.2465

0.2444

The graph shown below tells the pictorial idea of what minimum value of thickness required, there is a difference of 1.1 cm between conventional concrete and 1.5% modified concrete. In terms of percentage there is a difference of 4.3% between thickness of conventional and 1.5% modified concrete. Even a small thickness of 1.1cm can save a lot of resources/money when constructing pavement.

Minimum Thickness Required(m) 0.258

Thickness of Pavement

0.256

0.2554 0.2525

0.254 0.252 0.25

0.2465

0.248

0.2444

0.246 0.244 0.242 0.24 0.238 1

2

Conventional

0.5%

3

1.0%

4

1.5%

Figure 5-4: Minimum thickness curve

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6

Conclusion and Discussion

From all the data of Compressive strength, elasticity modulus and poison’s ration tests, we generated result of different days result. Comparting data all the types of concrete conventional, 0.5% , 1.0% and 1.5% modified concrete, we came to the following conclusion. 1. Conventional concrete gained quite well strength of 98.83% , whereas in case of modified concrete 0.5% modified achieved 92.03%, 1.0% gained 94.58% and 1.5% got the value of 95.31%. All the percentage value are of 48 MPa which is target strength. 2. It is observed that Modulus of Elasticity value increases as the fibre content increases. From 300505 MPa of conventional to 35700 MPa of 1.5% modified concrete, an increase of 6.3% in value of E-Modulus. Concluding that the overall value of modulus of elasticity is increasing on adding fibre content but rate of increasing is decreasing.

3. The poison’s ratio have an inverse relationship with Elasticity Modulus, which is exactly what we observed from the data above, the value of Poison’s ratio is continuously decreasing as the fibre content increases. There was a slight decrease from conventional to 0.5% but a great steep from 0.5% to 1.0% and then 1.0% to 1.5%, with whopping decrease of 42.1% from 0.19 of conventional to 0.11 of 1.5% modified concrete 4. In Rigid Pavement design, it was observed that 1.5% modified concrete can be provided with thickness 1.1 cm less than with conventional one. That is a difference of 4.3%, which can save a lot of resources/money while constructing pavement.

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7

References

1. IS4031:Part4-1988 - Determination Of Standard Consistency Of Cement 2. IS4031:Part5-1988 - Determination Of Initial & Final Setting Time Of Cement 3. IS4031:Part3-1988 - Determination Of Soundness Of Cement By Le-chatelier Method 4. IS2386:Part1-1963- Sieve Analysis Of Fine And Coarse Aggregate 5. IS2386:Part 3-1963 - Determination Of Specific Gravity And Water Absorption Of Fine & Coarse Aggregate 6. IS 10262 : 2009 - For concrete mix proportioning 7. IS 456: 2000 - Plain And Reinforced Concrete - Code Of Practice. 8. IRC:58-2015- Guidelines For The Design Of Plain Jointed Rigid Pavements For Highways 9. Reinforced concrete design by S N Sinha 10. ASTM C 469-02- Standard Test Method for Static Modulus of Elasticity and Poisson’s Ratio of Concrete in Compression 11. Controls instruction manual 12. Properties of glass fibers - http://textilefashionstudy.com/glass-fiber-physical-andchemical-properties-of-glass-fiber/ 13. EFFECT OF GLASS FIBER ON MECHANICAL PROPERTIES OF VIBRATED CONCRETE AND SELF COMPACTING CONCRETE- L. Rama Prasad Reddy, Dr M.G. Munireddy, Dr. M.L.V. Prasad 14. Rama Prasad Reddy, ‘EFFECT OF GLASS FIBER ON MECHANICAL PROPERTIES OF VIBRATED CONCRETE AND SELF COMPACTING CONCRETE’, International Journal of Engineering & Science Research, IJESR/October 2014/ Vol-4/Issue-10/760-765 15. Dhandhania VA, Coir Fiber Reinforced Concrete , Textile Science & Engineering, Dhandania and Sawant, J Textile Sci Eng 2014, 4:5

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