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111
CHAPTER 4
MATERIALS AND METHODOLOGY
This chapter deals with the description of various materials used in
the experimentation. Also it describes briefly the methodology adopted
to carry out the different tests as per relevant IS codes.
4.1 4.1 MATERIALS USED
4.1.1 Cement
The cement used in the experimentation was ordinary Portland
cement of 43-grade. The physical properties of the cement are given in
Table 4.1.
Table 4.1 Physical properties of ordinary Portland cement- 43 grade
Properties Results Limits as per IS 8112-1989
Fineness 5.5% 10%
Normal consistency 29%
Specific gravity 3.15
Setting time
Initial Final
105 min < 30 minutes
560 min ≯600 minutes
Soundness Test Le-chat expansion
2 mm 10 mm maximum
Compressive strength 3 days 7 days
28 days
24.50 ≮23 N / mm2.
35.50 ≮33 N / mm2.
44.44 ≮43 N / mm2.
4.1.2 Fine Aggregate
Locally available sand confirming to zone II with specific gravity of
2.6 was used as fine aggregate. The sand used was having a fineness
modulus of 2.92. The sand passing 1.18 mm and retained on 150
micron IS sieve was used. Table 4.2 gives the sieve analysis conducted
for fine aggregate.
112
Table 4.2 Sieve analysis of fine aggregate
IS sieve No. % passing Cumulative % retained
4.75 97.31 2.69
2.36 84.82 15.18
1.18 68.51 31.49
600µ 46.89 53.11
300µ 9.27 90.73
150µ 0.87 99.13
4.1.3 Steel Fibers
NOVOCON ISF1050 steel fibers were used in the experimental work.
These fibers are designed especially for the reinforcement concrete,
mortar and other cementitious matrix. The steel fibers of aspect ratio
25, 38 and 50 were used. Thickness of steel fiber was found to be
1mm. The tensile strength of steel fiber was found to be 1100 N/mm2.
The steel fibers of different aspect ratios are shown in plate 4.1, 4.2
and 4.3.
Plate Error! No text of specified style in
document. Steel fibers
of aspect ratio 38
Plate Error! No text of specified style in
document. Steel fibers
of aspect ratio 25
113
4.1.4 GI Fibers
GI fibers were obtained by cutting locally available GI wire. The
diameter of GI fiber was 1 mm. The aspect ratios adopted for the
experimentation were 25, 38 and 50. The tensile strength of GI fiber is
300 – 500 N/mm2. GI fibers of different aspect ratio are shown in plate
4.4, 4.5 and 4.6.
Plate Error! No text of specified style in
document. GI fibers of aspect ratio 38 Plate Error! No text of specified style in
document. GI fibers of aspect ratio 25
Plate Error! No text of specified
style in document. Steel fibers
of aspect ratio 50
114
4.1.5 Polypropylene Fibers
Polypropylene fibrillated harbourite fibers of aspect ratio of 800 and
1600 were used in the experimentation. The specific gravity was found
to be 0.91 and tensile strength of polypropylene fibers is 600 N /mm2.
Plate 4.7 and 4,8 show the polypropylene fibers of aspect ratio of 800
and 1600.
The properties of different fibers used are given in table 4.3. Table 4.3 Properties of different fibers used
Fiber type Length (mm)
Thickness / Diameter
Aspect ratio
Specific gravity
Plate Error! No text of specified style in
document. Polypropylene fibres
of aspect ratio 1600
Plate Error! No text of specified style in
document. Polypropylene fibres
of aspect ratio 800
Plate Error! No text of specified style in
document. GI fibers of aspect ratio 50
Steel fiber
25
38
50
GI fiber
25
38
50
Polypropylene fiber
6
12
4.1.6 Welded Mesh
Welded mesh of 12 G with 25 mm x 25 mm square opening was
used. The tensile strength of welded mesh is 1122 N/mm
shows the welded mesh used in the
4.1.7 Chicken Mesh
Chicken mesh of 20G with diamond opening was used.
shows the chicken mesh used in the experimentation.
Plate
Plate
115
1 mm 25 7.80
1 mm 38 7.80
1 mm 50 7.80
1 mm 25 7.70
1 mm 38 7.70
1 mm 50 7.70
7.5 µm 800 0.9
7.5 µm 1600 0.9
Welded mesh of 12 G with 25 mm x 25 mm square opening was
The tensile strength of welded mesh is 1122 N/mm
shows the welded mesh used in the experimentation.
Chicken Mesh
Chicken mesh of 20G with diamond opening was used.
shows the chicken mesh used in the experimentation.
Plate Error! No text of specified style in
document.Chicken mesh
Plate Error! No text of specified style in
document.Welded mesh
7.80
7.80
7.80
7.70
7.70
7.70
0.9
0.9
Welded mesh of 12 G with 25 mm x 25 mm square opening was
The tensile strength of welded mesh is 1122 N/mm2.Plate 4.9
Chicken mesh of 20G with diamond opening was used. Plate 4.10
116
4.1.8 Water
Ordinary potable water which is free from all the impurities such as
organic content, turbidity was used for mixing and curing of the
specimens.
4.1.9 Superplasticizer
To impart the additional desired properties and workability, a
superplasticizer Conplast SP 430 was used. The dosage of the
superplasticizer adopted throughout the experimentation was 1% by
weight of cement. Conplast SP 430 which is a sulphonated
naphthalene formaldehyde condensate is manufactured by Fosroc
chemicals (India) Pvt. Ltd., Bangalore. Conplast SP-430 is a brown
liquid, non-toxic and non-flammable liquid having shelf life of 12
months.
4.1.10 Air-Entraining Admixture
Air entrainment admixture Conplast AEA increases the resistance of
concrete to attack by frost and de-icing salts, reducing the problems of
surface scaling. It also assists in the formation of a stable cohesive
mix, reducing segregation and bleeding. Air entrainment admixture is
a translucent coloured liquid having specific gravity of 1.01 at 27°C,
pH of 7, which is manufactured by Fosroc Chemicals (India) Pvt. Ltd.,
Bangalore.
117
4.1.11 Accelerator
The Conplast NC accelerator which is manufactured by Fosroc
chemicals (India) Pvt. Ltd., Bangalore is non-flammable liquid having
shelf life of 12 months was used in the research work.
4.1.12 Retarder
The retarder used in the experiment was Conplast RP264. Conplast
RP264 is a dark brown liquid based on selected lignosulphonates,
specific gravity ranging between 1.170 – 1.190 at 27°C, and is
manufactured by Fosroc chemicals (India) Pvt. Ltd., Bangalore. It is
non-flammable liquid having shelf life of 12 months.
4.1.13 Waterproofing Compound
The waterproof compound used in the experiment was Conplast
X421IC. Conplast X421IC is a dark brown liquid based on
lignosulphonates which is manufactured by Fosroc chemicals (India)
Pvt. Ltd., Bangalore having shelf life of 12 months.
4.1.14 Flyash
Flyash is a by-product of the combustion of pulverized coal in
electric power generating plants and is obtained from Raichur Thermal
Power Plant. The physical and chemical properties of flyash are shown
in Table4.4 and Table4.5.
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Table 4.4 Physical properties of flyash
Density 2.17g/cm3
Bulk density 1.26g/c.c
Moisture content 2%
Specific gravity 2.03
Fineness 16%
Table 4.5 Chemical properties of flyash
Component IS: 3812-1981 Specifications
Flyash
SiO2 + Al2O3 + Fe2O3 70 minimum 99 – 99.1
SiO2 (alone) 35 minimum 58.8 – 59.1
MgO 5.0 max 0.22 – 0.34
Total sulphur SO3 2.75 max
Alkalis as Na2O 1.5 max 0.54
Loss on ignition 12 max 1.05 – 1.08
CaO - 0.86 – 1.02
K2O - 0.05 – 0.71
% on 45 µ sieve 34* 33
Lime activity at 7 days, MPa
4.25 4.10
Pozzolonic activity index at 28 days, % of control
75* 87
4.1.15 Silicafume
The silicafume used in this investigation is ELKEM Micro-silica
which is a by-product of the manufacture of silicon and ferrosilicon
alloys. This is amorphous and highly reactive. The physical and
chemical properties of silicafume are shown in Table4.6 and Table 4.7.
Table 4.6 Physical properties of silicafume
Particle size < 1µm
Bulk density 130 – 430 kg/m3
Specific gravity 2.2
Specific surface 15000 to 30000 m3/kg
Table 4.7 Chemical properties of silicafume
SiO2 93.70%
Moisture content 0.60%
L.O.I 1.07
Carbon 0.52%
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4.1.16 Metakaolin
MetaCem is a grade name of Calcined chinaclay manufactured from
20 Microns Limited, Thirunvelli, Tamilnadu. Physical and chemical
properties of metakaolin are as shown in Table 4.8 and Table 4.9.
Table4.8 Physical properties of metakaolin
Average particle size, µ m 1.5
Residue 325 Mesh (% max) 0.5
B.E.T. Surface Area m2/gm 15
Pozzolan Reactivity in mg Ca(OH)2/gm 1050
Specific gravity 2.5
Bulk density (gm/ltr) 300 ± 30
Brightness 80 ± 2
Physical form Off-white powder
Table4.9 Chemical properties of metakaolin
Chemical Composition Wt
Si02+Al2O3+Fe2O3 96.88%
Cao 0.39%
MgO 0.08%
TiO2 1.35%
Na2O 0.56%
K2O 0.06%
Li2O Nil
L.O.I 0.68%
4.2 CASTING OF SPECIMENS
Cages were prepared by tying the chicken mesh layer to welded
mesh at regular intervals by using binding wire. The prepared cages
were placed in the moulds which were oiled. Cement –sand slurry was
prepared with a mix proportion of 1:1 with a w /c ratio of 0.45, and a
superplasticizer dosage of 1% (by weight of cement). For steel and GI
fibers , initially a small quantity of slurry (10 mm) was poured into the
mould and then the fibers were placed in the mould and then the
slurry was infiltrated upto the brim level and was lightly compacted
using the table vibrator. Whereas for polypropylene fibers, fibers were
120
initially dispersed in the dry cement-sand mortar and then water of
required amount was added, and then the slurry was filled into the
mould and then lightly compacted. Then the moulds were covered with
wet gunny bags for 12 hours. After 12 hours, the specimens were
demoulded and kept in water for 28 days curing. For compressive
strength, specimens of dimensions 150 x 150 x 150 mm were cast. For
flexural strength, specimens of dimensions 100 x 100 x 500 mm were
cast. For impact strength, specimens of diameter 152 mm and
thickness 63.5 mm were cast.
4.3 TESTING OF SPECIMENS
4.3.1 Compressive Strength Test
The compressive strength test was conducted after 28 days of
curing. The compressive strength can be calculated in accordance with
IS 521-1959 using the formula
fc = P / A
Plate Error! No text of specified style in document.Cage for (a)
compressive strength,(b) flexural strength (c) impact strength specimens
(a)
(b)
(c)
121
Where fc - compressive strength of concrete
P – maximum load applied to the specimen
A – cross-sectional area of the specimen
4.3.2 Flexural Strength Test
Flexural strength also termed as modulus of rupture is a measure of
its ability to resist bending. The specimens casted for flexural strength
test were of dimensions 100 x 100 x 500 mm. The effective span was
400 mm and the specimens were subjected to two point loading, the
distance between the loads was 133 mm. The test procedure was
carried out in accordance with IS 516-1959.
The flexural strength of the specimen shall be expressed as the
modulus of rupture and shall be calculated using the formula
fcf = P x L / b d2
Where fcf – flexural strength
P – maximum load applied to the specimen
L – c/c distance between the two supports
b – width of the specimen
d – depth of the specimen
Plate Error! No text of specified style in
document.Failure of compression specimen
122
4.3.3 Toughness
The toughness is measured by using the load deflection curve. The
toughness index, If is given by
Area under load-deflection curve until the load reaches zero for fiber composite
If = -------------------------------------------------------------------------------- Area under load–deflection curve until the load reaches zero for plain matrix
In the ASTM procedure, the denominator in the above equation is
taken as the area under the load-deflection curve upto the first crack.
The first crack is assumed to occur at the point where the load
deflection curve deviates from the initial linear portion. The numerator
is taken as the area under the load deflection curve upto a certain
specified deflection. Three levels of deflection namely, 3δ, 5.5δ and
10.5δ are suggested for the numerator. The term δ is the deflection
upto 1st crack. Thus
Area under the load deflection curve upto 3δ
I5 = -------------------------------------------------------
Area under the load deflection upto δ
Area under the load deflection curve upto 5.5δ
I10 = ----------------------------------------------------------
Area under the load deflection upto δ
Plate Error! No text of specified style in document.Failure of flexural specimen
123
4.3.4 Impact Strength – Drop Weight Test
Impact strength of concrete is a measure of the ability to absorb the
shock or sudden impact due to external load. The impact strength can
be expressed in terms of energy required to cause crack and is
expressed in terms of N-m.
The impact test specimens were of size 152 mm in diameter and
63.5 mm thick and are subjected to repeated loads (blows) by
dropping a 4.5 kg hammer from a height of 457 mm. Number of blows
required to cause first visible crack is noted as the first crack strength.
Plate Error! No text of specified style in Failure of impact specimens
Plate Error! No text of specified style in
document.Impact test components
Plate Error! No text of specified style in document.Impact test setup
124
The loading is continued until the specimen fails and opens up such
that it touches three of the four positioning lugs. The Number of blows
required to cause this condition is recorded as the final failure. The
impact strength was calculated as follows
Impact energy = mghN
= w/g * g *h *N
= whN (N-m)
Where m – mass of the ball
w – weight of the ball in N
g – acceleration due to gravity
h – height of drop in m
N – average number of blows to cause failure
4.3.5 Freezing and Thawing Test
After 28 days of curing, the specimens were surface dried and then
they were kept in freezer at a temperature of -14°C for 24 hours. After
24 hours of freezing, the specimens were taken out and kept in open
atmosphere for 24 hours. This completes one cycle of freezing and
thawing. The specimens were subjected to such 90 cycles of freezing
and thawing. After 90 cycles, the specimens were surface dried, and
were tested for their respective strengths.
Plate Error! No text of specified style in document.Specimens
subjected to freezing
125
4.3.6 Temperature Test
After 28 days of curing, the specimens were surface dried. The
specimens were placed in the oven for 4 hours at a sustained
temperature of 100°C. After 4 hours, the oven was switched off and
the specimens were allowed to cool in the oven for few hours. Once the
specimens were cooled, the specimens were taken out. The same
procedure was done for the specimens for 200°C and 300°C. After
subjecting the specimens for the sustained elevated temperature, the
specimens were tested for their respective strengths.
4.3.7 Alternate Wetting and Drying Test
After 28 days of curing, the specimens were surface dried. The
specimens were kept in open atmosphere for 24 hours. After 24 hours
of drying, the specimens are placed in water for 24 hours. This
completes one cycle of alternate wetting and drying. After 90 such
cycles the specimens were surface dried and tested for their respective
strengths.
Plate Error! No text of specified style in document.Specimens
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