material properties and casting of test...

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Chapter-3

MATERIAL PROPERTIES

AND CASTING OF TEST

SPECIMEN

67

CHAPTER 3: MATERIAL PROPERTIES AND CASTING OF TEST

SPECIMEN

3.1 GENERAL 68-68

3.2 OVERVIEW OF EXPERIMENTAL PROGRAMME 68-69

3.3 MATERIALS USED AND THEIR PROPERTIES 70-70

3.3.1 Cement 70-70

3.3.2 Fine Aggregate 71-71

3.3.3 Coarse Aggregate 72-73

3.3.4 Silica Fume 73-73

3.3.5 Water 73-74

3.3.6 Superplasticizer 75-75

3.3.7 Reinforcement 75-75

3.4 MIX DESIGN 75-77

3.5 CASTING OF SPECIMEN 77-82

3.6 MECHANICAL PROPERTIES 82-87

3.7 SUMMARY 87-89

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CHAPTER-3

MATERIAL PROPERTIES AND CASTING OF TEST

SPECIMEN

3.1 GENERAL

This chapter deals with the experimental program for the

proposed research work. The materials used in this research are

cement, coarse aggregate, fine aggregate, silica fume, superplasticizer,

water and high yield strength deformed bars as reinforcement. This

chapter deals the testing of materials used, mix design, dosage of

mineral and chemical admixtures and casting of specimens.

3.2 OVERVIEW OF EXPERIMENTAL PROGRAMME

The experimental program is divided in to five stages. The first

stage deals with an assessment of material properties used in the

research work. The second stage is associated about mix design of

concrete and based on the results obtained in the first stage. The third

stage is associated about the casting of cylinders, cubes and slab

specimens that are used in the research based on second stage mix

design. The fourth stage deals with the testing of cube and cylinder

specimens. The fifth stage is testing of slab specimens under flexure,

punching shear with simply supported and fixed edge conditions and

slab specimens under impact loading with all edges fixed condition.

Table 3.1 outlines the stages of the research work.

69

Table: 3.1 Project overall view

STAGE-I Physical properties of various materials used

in the research

STAGE-II Mix design

STAGE-III Casting of specimens (Cubes, Cylinders and

Slabs)

STAGE-IV Mechanical properties of concrete mixes

STAGE-V

Structural

properties of

concrete slabs

Testing of two way slabs

under flexure with all

edges simply supported


under flexure with all

edges fixed


under punching shear

with all edges simply

supported


under punching shear

with all edges fixed


under impact with all

edges fixed

70

3.3 MATERIALS USED AND THEIR PROPORTIES

Various tests on materials like, cement, fine aggregate, coarse

aggregate and water have been conducted to confirm their suitability

to use in concrete making as per the procedures laid down in IS

Codes. It is observed that all the materials satisfy the relevant

provisions of IS Code of practice. The results of various tests

conducted on raw materials are presented in this chapter. High

Performance Concrete (HPC) and Reinforced Cement Concrete (RCC)

slabs elements are produced in the laboratory using these materials to

evaluate the behaviour of HPC and RCC slabs.

3.3.1 Cement

Ordinary Portland cement of 43 grade of Ultra-tech Cement

confirming to IS: 8112-198954 standards was used. The specific

gravity, normal consistency, initial and final setting times and

compressive strength of cement tests had been carried out and the

results are presented in Table 3.2.

Table: 3.2 Test results of cement

S.No Test Experimental values

Suggested values as per IS 8112-198954 Specifications

1 Fineness of Cement By using blains specific surface area (m2/kg)

320

225

2 Specific Gravity 3.14

3 Normal Consistency (%) 32

4 Setting time (minutes)

Initial Final

105 375

Min≥ 30 minutes Max ≤ 600 minutes

5 Compressive Strength (N/ mm2)

3 days 7 days 28 days

30.00 36.00

58.00

23.00 33.00

43.00

71

3.3.2 Fine Aggregate

The locally available sand confirming to Zone-II grade of Table 4

of IS 383-197050 has been used as Fine Aggregate. Tests have been

carried out as per the procedure given in IS Codes and the results are

tabulated in Table 3.3 and 3.4.

Table: 3.3 Sieve analysis of fine aggregate

Sl.No I. S Sieve Designation

Weight retained

(gms)

% of weight

retained

Cumulative % of weight retained

% of Passing

1 10 mm 0.00 0.00 0.00 100

2 4.75 mm 55.00 5.50 5.50 94.50

3 2.36 mm 90.00 9.00 14.50 85.50

4 1.18 mm 143.00 14.30 28.80 71.20

5 600 µ 204.00 20.40 49.20 50.80

6 300 µ 312.00 31.20 80.40 19.60

7 150 µ 178.00 17.80 98.20 1.80

8 Pan 18.00 1.8 100.00 0.00

Fineness Modulus = 2.711 Total = 271.10

Table: 3.4 Physical properties of fine aggregate

S.No Property Value


2 Fineness Modulus 2.711

3 Grading Zone – II

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3.3.3 Coarse Aggregate

The locally available crushed granite has been used as coarse

aggregate in this investigation. For the mix design of HPC and normal

concrete it is necessary to know the properties of material i.e., Sieve

analysis, Specific gravity, density and water absorption. The tests

have been carried out as per the procedure given in IS Codes and the

results are presented in Table 3.5, 3.6 and 3.7.

Table: 3.5 Sieve analysis of 20 mm coarse aggregate

Sl. No I.S. Sieve Designation

Weight retained

(gms)

% of weight

retained

Cumulative % of weight

retained % of

Passing

1 40 mm 0.00 0.00 0.00 100

2 20 mm 324.00 3.24 3.24 96.76

3 10 mm 8416.00 84.16 87.4 12.60

4 4.75 mm 1224.00 12.24 99.64 0.36

5 2.36 mm --- --- --- ---

Table: 3.6 Sieve analysis of 12.5 mm coarse aggregate

Sl. No

I.S. Sieve Designation

Weight retained

(gms)

% of weight

retained

Cumulative % of weight

retained % of

Passing

1 40 mm 0.00 0.00 0.00 100

2 20 mm 0.00 0.00 0.00 100

3 12.5 mm 192.00 3.84 3.84 96.16

4 10.00 mm 2896.00 57.92 61.76 38.24

5 4.75 mm 1694.00 33.88 95.64 4.36

6 2.36 mm --- --- --- ---

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Table: 3.7 Physical properties of coarse aggregate

Sl.No Property Value


2 Bulk Density Kg/m3)

Loose

Compacted

1320

1535

3 Water absorption (%) 0.52

3.3.4 Silica Fume

Silica fume is a byproduct of producing silicon metal or

ferrosilicon alloys. One of the most beneficial use of silica fume in

concrete is of its chemical and physical properties, it is a very reactive

pozzolan. Elkam brand silica fume is used for the investigation and

the properties supplied by the supplier are, colour appears to be Gray,

Bulk density is 500 Kg/m3, specific surface are 15-30 m2/gm and

average particle size is 0.2micron.

3.3.5 Water

Water is the key ingredient in producing concrete clean potable

fresh water which is free from concentration of acid and organic

substances has been used for mixing and curing the concrete. The

results of various tests are presented in Table 3.8.

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Table: 3.8 Physical properties of water

S.No Parameter Amount

1 pH at 250 7.58

2 Taste Agreeable

3 Appearance Normal

4 Turbidity (NT Units) 7.92

5 Colour (Hazen Units) 3.2

6 Hardness (mg/l) 400

7 Sulphates (mg/l) 329

8 Chlorides (mg/l) 72

9 Odour (Ton) 3.02

10 Suspended Solids 135

11 Total Dissolved Solids 212

12 Total hardness as Ca Co3 112

13 Calcium as Ca 14

14 Magnesium as Mg 42

15 Carbonate Hardness as Ca Co3 40

16 Non-Carbonate Hardness as Ca Co3 95

17 Bi-Carbonate Hardness as Ca Co3 12

18 Carbonate as Co3 32

19 Bi-Carbonate as H Co3 27

20 Chloride as CI 20

21 Nitrate as N 26

22 Floride as F 0.38

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3.3.6 Superplasticizer

To impart the required workability superplasticizer has been

used in this investigation. Superplasticizers are linear polymers

containing sulfuric acid groups attached to the polymer backbone at

regular intervals. The superplasticizer used for this investigation is

CONPLAST 430 manufactured by FOSROC and it complies to IS 2645-

200353.

3.3.7 Reinforcement

All the slabs are reinforced with 6mm diameter of Fe 415 grade

high yield strength deformed steel rods confirmed to IS: 1786-200852.

3.4 MIX DESIGN

Target Mean Strength for 28 days of the HPC concrete was set

as 68.25 MPa, and Control concrete was 31.60 MPa. The water

cement ratios for the above mixes used are 0.29 and 0.50 respectively.

In Indian standards IS 10262-200955 describes for the mix

design of low to medium strength of concretes and it does not include

the design of concrete mixes with incorporation of pozzolans. Hence in

this investigation the mix design procedure adopted for reinforced

cement concrete and high performance concrete was with ACI method.

For the present investigation the weight of coarse aggregate and

fine aggregate are maintained at a ratio of 57.46:42.54 for all the

mixes and water content for the HPC mixes are constant at 143 kg/m3

and for RCC mix was 186 Kg/m3 and the superplasticizer was

constant for HPC mixes at the rate 5.11 kg/m3 and no superplasticizer

were used for RCC mixes. Silica fume contents used in this

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investigation are 0 to 25% and water to cementitious ratios are 0.29

and 0.50 for HPC and RCC mixes respectively.

To produce HPC, various mixes were prepared with the addition

of silica fume and superplasticizer. In these mixes the dosage of

additive materials are different and the specific weights of each

materials were presented in Table 3.9. The RCC mix was taken as

reference mix and weights of materials for this mix also presented in

Table 3.9.

Table: 3.9 Mix proportions of concrete

Nomenclature

Cement (Kg)

Fine Aggregate (Kg)

Coarse Aggregate

(Kg) Water (Kg)

Superplasticizer

(Kg)

Silica fume (Kg)

RCC-0 372 656 1184 186 0 0.00

HPC-0 511 773 1044 143 5.11 0.00

HPC-5 486 773 1044 143 5.11 25.55

HPC-10 461 773 1044 143 5.11 51.10

HPC-15 436 773 1044 143 5.11 76.65

HPC-20 411 773 1044 143 5.11 102.20

HPC-25 386 773 1044 143 5.11 127.75

The concrete mixes were prepared based on the mix proportions

mentioned in Table 3.9. Workability of all above mixes observed in

terms of slump. The tests were carried out as per the procedure given

in IS 1199-195951 and the results are presented in Table 3.10.

In the present experimentation the slump values are ranging

from 95 to 58 mm for 0 to 25% replacement of cement by silica fume.

77

Similar observations are made by Patil Shreekedar and Kumbha

(2013)92, the slump values ranging from 95 to 68 mm for replacement

of cement by silica fume 5 to 25%.

Table: 3.10 Workability of concrete

Nomenclature % of silica fume

Slump (mm)

RCC-0 0 52

HPC-0 0 95

HPC-5 5 82

HPC-10 10 77

HPC-15 15 71

HPC-20 20 64

HPC-25 25 58

3.5 CASTING OF SPECIMENS

The cube, cylinders and slab specimens were prepared for the

mixes HPC and RCC and the results are tabulated in Table 3.11.

a) 150 x 150 x 150 mm standard cubes for compressive strength.

b) 150 mm diameter and 300 mm height standard cylinders for

cylindrical compressive strength and split tensile strength.

c) Square slabs of size 1100 x 1100 x 50 mm with tensile

reinforcement as per IS 456 minimum spacing criteria and a

clear cover of 10 mm and 12 no of 6mm diameter bars are

equally distributed in both ways @ 100 mm centre to centre.

The dimensions of the slab specimens are shown in Figure 3.1.

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The slabs with the reinforcement arrangement shown in Figure

3.2.

Table: 3.11 Specimen details of the project

Nomenclature Percentage of

replacement of silica fume

No. of cube specimens

No of cylinder

specimens

No of slab specimens

RCC-0 0 6 6 15

HPC-0 0 6 6 15

HPC-5 5 6 6 15

HPC-10 10 6 6 15

HPC-15 15 6 6 15

HPC-20 20 6 6 15

HPC-25 25 6 6 15

Cubes and cylinders are cast with standard cube and cylinder

moulds. The slumps were measured at the time of casting cubes and

are listed in Table 3.11. The cube and cylinder specimens are

demoulded after 24 hrs and were cured for 28 days.

Fabricated steel moulds are used to cast the slab specimens of

required size. Two L-shaped angle frames with a depth of 50mm are

connected to a flat plate by using bolt and nut at the bottom. Cross

stiffeners were provided at the bottom to prevent deflection while

casting the slab specimens. The gaps were sealed by using wax and

thin card boards to prevent leakages. The slab specimens were casted

and were cured in curing pond for 28 days. After taken out the slab

specimens from the pond, they were coated with white paint, to

achieve clear visibility of cracks during testing. The casting and curing

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process of the slab specimens were shown from Figure 3.3 to Figure

3.8.

Fig: 3.1 Dimension of typical slab specimen

Fig: 3.2 Reinforcement details of slab specimen

Fig: 3.3 Reinforcement placed in the mould

50

1000

200 200

1000

1000

50

50

50

50

80

Fig: 3.4 Slump test before casting of slabs

Fig: 3.5 Slab specimen during casting

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Fig: 3.6 Slab specimen during casting

Fig: 3.7 Slab specimens after casting

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Fig: 3.8 Curing process

3.6 MECHANICAL PROPERTIES

Compression testing machine of capacity 2500 KN is used for

testing the concrete specimens. While testing the specimens,

precautions were taken to ensure load is axial. Tests are conducted on

the specimens for cube compression, cylinder compression and split

tensile strengths. The average three test results for each mix are

presented in Table 3.12. A Graph is drawn for cube compressive

strength Vs percentage replacement of cement by silica fume are

shown in Figure 3.9, similarly graph were drawn for cylindrical

compressive strength Vs percentage replacement of cement by silica

fume and split tensile strength Vs percentage replacement of cement

by silica fume and are shown in Figure 3.10 and 3.11 respectively.

83

Cubes of HPC and normal concrete (RCC M25) specimens are

tested in the laboratory. For HPC-0 to HPC-15 the cube compressive

strength increases from 59.55 to 71.11 MPa and from HPC-15 to HPC-

25 the cube compressive strength decreases from 71.11 to 63.11 MPa

and where as RCC-0 reported only 40.18 MPa. Maximum value of

cube compressive strength is obtained at 15% silica fume content and

the values are presented in Table 3.12.

In the present investigation cube compressive strengths are

increased up to 15% replacement of cement by silica fume, beyond

that compressive strengths are decreased. Similar observations are

made by Shanmugapriya and Uma (2013) 107 and Patil Shreekedar

and Kumbhar (2013)92 in their experimentation cube strengths are

increased up to 15% replacement of cement by silica fume beyond

15% the cube compressive strengths are decreased and Debabrata

Pradhan and Dutta (2013)33 the strengths are increased up to 20%

and 10% by subhro chakraorty and samaresh pan (2014)113.

Cylinders of HPC and normal concrete (RCC M25) specimens

are tested in the laboratory. The cylindrical compressive strength of

HPC cylinder specimens increased up to 15% replacement i.e., from

HPC-0 to HPC-15 the cylindrical compressive strength increased from

47.37 to 55.85 MPa and for HPC-15 to HPC-25 the cylindrical

compressive strength decreased from 55.85 to 48.78 MPa, where as

RCC-0 reported only 32.01 MPa. Maximum value of cylindrical

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compressive strength is obtained where the silica fume replacement of

cement is at 15%, and these values are presented in Table 3.12.

Cylinders of HPC and normal concrete (RCC M25) specimens

are tested in the laboratory. The split tensile strength of HPC cylinder

specimen increased up to 15% replacement i.e., from HPC-0 to HPC-

15 the split tensile strength increased from 5.12 to 5.66 MPa and for

HPC-15 to HPC-25 the split tensile strength decreased from 5.66 to

5.33 MPa, where as RCC-0 reported only 3.21 MPa. Maximum value of

cylinder split tensile strength is obtained where the replacement of

cement by silica fume is at 15%, and these values are presented in

Table 3.12.

Similar observations are made by Shanmugapriya and Uma

(2013)107.

In the present investigation cube compressive strength for 7

days to 28 days was in the range 0.84 to 0.90 for various mixes.

Similar observations were observed by the Vinayagam (2012)130 and

Debabrata and Dutta (2013)33.

The ratio of cylindrical compressive strength to cube

compressive strength was 0.77 to 0.795 in the present investigation.

Similar observations are found by Vinayagam (2012)130, Gardner et

al., (1988)40, Arloglu (1985)19 and Nihal et al., (2006)87.

85

In the present investigation cube compressive strength, cylinder

compressive strength and split tensile strengths are increased up to

15% replacement of cement by silica fume. Similar observations are

observed by bhanja and sengupta (2005)24 and Patil shreekedar and

kumbhar (2013)92. This is mainly due to reaction between silica and

the free calcium hydroxide during the hydration of cement and forms

extra calcium hydroxide during the hydration of cement and forms

extra calcium silica hydrate (S-S-H).

In the current study the ratio of split tensile strength to cube

compressive strength was 0.079 to 0.086. Similar trends are observed

by Gardner et al., (1988)40, Arloglu (1985)19 and Nihal et al., (2006)87.

Table: 3.12 Mechanical properties of concrete

Nomenclature

% of silica fume

Cube compressive strength (fc)

in MPa

Cylinder compressive

strength (f1c) in MPa

Split tensile

strength (ft) in MPa

RCC-0 0 40.18 32.01 3.21

HPC-0 0 59.55 47.37 5.12

HPC-5 5 62.67 49.49 5.28

HPC-10 10 65.33 50.90 5.45

HPC-15 15 71.11 55.85 5.66

HPC-20 20 67.33 52.32 5.42

HPC-25 25 63.11 48.78 5.33

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Fig: 3.9 Percentage of silica fume Vs Cube compressive strength

0 5 10 15 20 2505

10152025303540455055606570

Cyl

inde

r co

mpr

essi

ve s

tren

gth

(MPa

)

Percentage of silica fume

RCC HPC

Fig: 3.10 Percentage of silica fume Vs Cylindrical compressive

strength

0 5 10 15 20 2505

10152025303540455055606570758085

Cub

e co

mpr

essi

ve s

tren

gth

(MPa

)


RCC HPC

87

0 5 10 15 20 250

1

2

3

4

5

6

7

8

9

10

Cyl

inde

r sp

lit t

ensi

le s

tren

gth

(MPa

)


RCC HPC

Fig: 3.11 Percentage of silica fume Vs split tensile strength

3.7 SUMMARY

Various tests on materials like, cement, coarse aggregate, fine

aggregate and water have been conducted to confirm suitability for

their use in making concrete as per the procedures in IS codes. It is

observed all the materials satisfy the relevant provisions of IS Code of

practice. The results of tests conducted on materials are presented in

this chapter. HPC and RCC slab specimens were produced in the

laboratory by using the above materials and behavior of HPC slab

specimens were investigated and are listed in Table 3.13. The next

chapter investigates the behavior of HPC slabs in Flexure.

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Table: 3.13 Nomenclature of slabs

Sl. No.

Slab Designation Explanation

1 RCCS-0 RCC slabs with all four edges simply supported and 0% replacement of cement by silica fume.

2 HPCS-0 HPC slab with all four edges simply supported and 0% replacement of cement by silica fume.




6 HPCS-20 HPC slab with all four edges simply supported and 20 % replacement of cement by silica fume.


8 RCCF-0 RCC slabs with all four edges fixed, containing 0% replacement of cement by silica fume.

9 HPCF-0 HPC slab with all four edges fixed and 0% replacement of cement by silica fume.






89

The nomenclature used for the designation of different slab

specimens is chosen to understand easily and the details of

nomenclature used are explained below.

The first 3 letter in the nomenclature ‘HPC’ indicate High

Performance Concrete, ‘RCC’ indicate Reinforced Cement Concrete.

4th Letter indicate ‘S’ and ‘F’, simply supported and fixed

respectively.

The numerical in 5th position indicate the percentage weight of

cement replaced by silica fume.

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