STUDY ON BOND MECHANISM OF PSWC BARS WITH CONCRETE

STUDY ON BOND MECHANISM OF PSWC
BARS WITH CONCRETE
1
SHOIB BASHIR WANI
RRN 131202601029
PROJECT GUIDE
Dr. M.S. HAJI SHEIK MOHAMMED
PROFESSOR & HEAD
SCHOOL OF CIVIL ENGINEERING
B S ABDUR RAHMAN CRESCENT INSTITUTE OF SCIENCE & TECHNOLOGY

INTRODUCTION
 PSWC- Plain surface with wave-type configuration,a rebar for
durable concrete construction at zero cost addition and much
more
 The yield strength & the bond strength of HYSD bars > plain round
mild steel straight bars
 Durability issues related to the use of HYSD bars in RCC & problems
of early distress
 Early corrosion due to the provision of surface protrusions in HYSD
bars for achieving the higher bond strength.
 Alternative solution : A new type of reinforcing steel bar (named as
PSWC-bar) with normal plain round surface and deformed axis is
proposed.
2

(b) Corroded Twisted Rebar
PSWC bar
View of New rebar
3

BOND MECHANISM OF DEFORMED BARS &
PLAIN ROUD BARS
DEFORMED BARS PLAIN ROUND STRAIGHT BARS
1) Bond resistance due to chemical
adhesion between the bar and the
surrounding concrete;
1) Adhesive resistance: Adhesive resistance
is developed before the beginning of slip of
the bar relative to the adjacent surrounding
concrete;
2) Bond resistance due to friction between
the bar surface and surrounding concrete
surface;
2) Sliding resistance: Sliding resistance is
developed because of the movement of the
bar relative to the adjacent surrounding
concrete.
3) Bond resistance due to mechanical
interlock between the lugs of the bar and
the surrounding concrete.
4

NEED FOR PRESENT STUDY
 Studies have shown that use of PSWC-bars increases the load
carrying capacities of concrete beams and columns.
 PSWC bar reinforced RCC elements exhibits excellent flexural
and ductility behaviour as compared to mild steel rebars.
 Excellent bond strength between steel – concrete is essential
for enhanced performance of RCC structures.
 It is necessary to understand the bond mechanism between
PSWC bar and Concrete for effective optimization and
subsequent usage.
5

SCOPE OF INVESTIGATION
 To study the Bond mechanism between PSWC bar and
Concrete.
 To conduct experiments to ascertain Bond strength
between PSWC bar and Concrete as per Indian
Standards (Pull out Test as per IS 2770:1967) and
American Standards (Beam End Specimens as per
ASTM A944/A944-91)
 To propose bond failure mechanism based on
analytical and experimental results.
6

MATERIAL STUDY
The materials used in experimental study
include:
i. 53 grade OPC
ii. 2.36mm downgraded river sand
iii. 20mm downgraded coarse aggregate
iv. MS rebar of fy= 250 MPa, HYSD parallel rib rebar,
HYSD diamond rib rebar of fy= 500 MPa of size 16
mmØ
7

CONSTITUENT PROPERTIES
Cement (53 grade OPC)  Specific gravity – 3.12
Fine Aggregate (2.36 mm
downgraded)
 Fineness modulus – 3.05
 Specific gravity – 2.4
 Water absorption – 5.75%
 Confirming to zone - II
Grading conforming to IS 383-1970
Coarse Aggregate (20 mm
downgraded)
 Specific gravity – 2.5
 Water absorption – 0.25%
Grading conforming to IS 2386-1963
TABLE 1: MATERIAL PROPERTIES
8

TABLE 2: CHEMICAL COMPOSITION TEST RESULTS
Chemical
Composition
Type Of Rebar
MS rebar Results
(16mm Ø)
HYSD (Parallel ribs)
Results (16mm Ø)
HYSD (Diamond ribs)
Results (16mm Ø)
Carbon, (%) 0.284 0.203 0.222
Manganese, (%) 0.553 0.696 0.567
Silicon, (%) 0.157 0.208 0.104
Sulphur, (%) 0.028 0.024 0.024
Phosphorous, (%) 0.036 0.033 0.032
Chromium, (%) 0.190 0.092 0.186
Nickel, (%) 0.099 0.068 0.069
9

TABLE 3: TENSION TEST RESULTS
Type of Rebar
PROPERTIES
Yield Strength
(MPa)
Ultimate Strength
(MPa)
% Elongation
% Reduction
In Area
MILD STEEL
466.72 583.40 27.5 54.23
HYSD PARALLEL RIB
498.36 622.96 22.5 55.45
HYSD DIAMOND
RIB
547.77 684.72 26.25 54.90
10

11
TABLE 4: MIX PROPORTIONS FOR 1M3 OF M30 CONCRETE AS PER IS
10262:2009 & VALIDATION OF MIX DESIGN
Cement
(kg)
Fine Aggregate
(kg)
Coarse Aggregate
(kg)
Water
(litre)
438 588.74 1044.22 197
1 1.344 2.384 0.45
37.63
44.66
42.66
38.98
35.25
42.32
39.09 38.21
0
5
10
15
20
25
30
35
40
45
50
B1 B2 B3 B4 B5 B5 B6 B7
IS Pull-Out Specimen Concrete
Mix
ASTM Beam-End Specimen
Concrete Mix
28
days
Compressive
Strength
in
MPa
Cube
Identification
Cube
Weight
(kg)
Ultimate
Load
(kN)
Compressive
Strength
(N/mm2)
B1 2.65 376.3 37.63
B2 2.72 446.6 44.66
B3 2.68 426.6 42.66
B4 2.71 389.8 38.98
B5 2.77 352.5 35.25
B6 2.79 423.2 42.32
B7 2.59 390.9 39.09
B8 2.75 382.1 38.21

DEVELOPMENT OF COATING SYSTEM
 Site oriented cement polymer anticorrosive coating (passivating type)
system was proposed in recent times (M.S.Haji Sheik, 2008) and
accordingly cement polymer anticorrosive solution was developed.
 It comprises of nitrite, styrene-butadiene polymer and other
additives.
 The anticorrosive polymer solution is milky white in colour, pH
around 12.50 and density of 1.03 g/cc.
 The solution is mixed with 90 micron sieved ordinary Portland
cement and applied over the rebars as coating by simple brushing
12

13
Loose rust removal by steel wire brush cleaning
Application of Ist coat of CPAC
Air drying: 8-12 hours
Application of 2nd coat of CPAC
Coating thickness: 150 + 50 μm for 1coated rebars
Coating Thickness: 200 + 50 μm for 2coated rebars
DEVELOPMENT OF CEMENT POLYMER ANTICORROSIVE COATING PROCESS

BIS PULL-OUT SPECIMENS
S.No. Type of bar Offset &
pitch
length
Nominal size
of bar
(mm)
Bonded length
(mm)
Number of
Specimens
1 HYSD Parallel Rib Bar -
16 80 9
HYSD Parallel Rib Bar with
CPAC-1 coat
-
HYSD Parallel Rib Bar with
CPAC-2 coat
-
2 HYSD Diamond Rib Bar -
16 80 9
HYSD Diamond Rib Bar with
CPAC-1 coat
-
HYSD Diamond Rib Bar with
CPAC-2 coat
-
3 MS Bar -
16 80 9
MS Bars with CPAC- 1 coat -
MS Bars with CPAC-2 coat -
4 PSWC bar 4mm &
80mm
16 80 3 15

16
Bonded Length (= 5Ø) & Unbonded
Length
4-Legged Mild Steel Clamp Used To
Maintain Verticality of Rebar
Extended length from
bottom face = 20mm

REBARS USED IN PULLOUT TESTING AS PER
BIS INDICATING BONDING & UNBONDED REGION
17
Uncoated MS rebar & HYSD rebar with
different rib configuration
Coated MS rebar & HYSD rebar with different rib
configuration

18
PSWC rebar with 4 mm offset & 80
mm pitch
Arrangement of Mould for Casting
Pullout Specimen

Arrangement of Mould for Casting
Pull-out Specimen
Casted BIS Pullout Specimens
19

TESTING OF BIS PULLOUT SPECIMENS
 A special fixture to hold the specimen during the testing was fabricated as per IS
2770-1967(Part I) – 1967 (Reaffirmed 2007) (Indian Standard Methods of Testing
Bond in Reinforced Concrete).
 Dial gauge with a least count of 0.001 mm was used to measure free end (FE) slip
and a dial gauge with 0.01 mm least count was used to measure loaded end (LE)
slip.
 The usable bond strength values were calculated from load at 0.025 mm free end
slip and 0.25 mm loaded end slip.
 The load slip behaviour at free end and loaded end are also drawn to analyse the
behaviour of rebar configuration and protective coating on bond strength
development.
 Load cell of range 500 kN (Model: ELC-30S) was used as shown in the setup to
compare the load shown by UTM and the data logger setup for accurate results
20

21
View of Pull-Out Test in Progress
FE Dial gauge
FE Dial gauge Load cell placed
in the
arrangement

S.No Description Original Dimensions Scaled Down Dimensions
1 Length 600 mm 450 mm
2 Breadth 230 mm 230 mm
3 Height 300 mm 300 mm
22
 Concrete beam – end test specimen of size (450 X 230 X 300 mm) were cast with eccentrically
embedded rebar (test rod) of 16mm diameter and its bonded length was given as 200mm as per ASTM
test procedure.
 The rebar is provided an extension up to 20 mm to the rear face of the beam to measure the slip value
of the free end and also the rebar is extended over the front face for a length to facilitate gripping of
rebar on the testing machine
TABLE 5: COMPARISON OF ORIGINAL AND SCALED DOWN TEST SPECIMEN

REBARS USED IN CASTING ASTM BEAM
END SPECIMENS
1) 16 mm Ø Mild steel rebar.
2) 16 mm Ø HYSD rebar with parallel ribs.
3) 16 mm Ø PSWC rebar with 4 mm offset and 200 mm pitch.
23
PSWC Bar of 4mm Offset & 200mm Pitch Length Showing
Un-Bonded Regions Covered with Plastic Sleeves.

24
Detailing Reinforcement of Beam – End
Test Specimen
Flexural Reinforcement
Test Rod
Casted ASTM Pullout Specimens

Testing of ASTM Beam End Specimens
25
Schematic of ASTM
Pullout Test Setup

BOND STRENGTH TEST USING BIS PULLOUT SPECIMENS
 30 BIS pull-out specimens were tested
 The test results were analysed as per procedure outlined in IS 2770-1967 by observing the load at
0.25mm loaded end (LE) slip, 0.025mm free end (FE) slip and ultimate failure load
Types of specimen
Load (kN)
Usable Bond
Strength
(N/mm2)
Variation
(%)
0.025mm
FE slip
0.25 mm LE
slip
Ultimate
load (kN)
Mild steel 17.91 16.89 32 4.20 -
HYSD
parallel ribs
37.80 32.60 102 8.10 +92.85
HYSD
diamond ribs
39.00 35.37 112.61 8.79 +93.33
Table 5: Observations on Pullout Test for 16mm Diameter Control
Mild Steel, HYSD rebar with Parallel Ribs and HYSD rebar
with Diamond Ribs
26

Figure 1. Load vs Slip Behaviour of Control MS bar, HYSD Rebar with Parallel Ribs and
HYSD bar with Diamond Ribs
27
0
20
40
60
80
100
120
0 1 2 3 4 5 6
Load
(kN)
Slip (mm)
HYSD Parallel Rib
Control
MS Control
HYSD Diamond Rib
Control
a. Free End Slip Behaviour a. Loaded End Slip Behaviour

Table 6: Observation on Bond Strength Test for 16mm Diameter uncoated, single
and double coated nano modified CPAC HYSD rebar with Parallel Ribs
28
Types of Rebar
Load (kN)
Usable Bond
Strength
(N/mm2)
Variation
(%)
0.025m
m FE
slip
0.25 mm
LE slip
Ultimate
load
(kN)
Uncoated rebar
37.8 32.6 102 8.10 -
Single Coated CPAC rebar – CC
49.6 25 97.6 6.21 - 23.33
Double Coated CPAC rebar –
CC
24.2 25 105.2 6.01 - 25.80

Figure (2) Load-Slip Behaviour of 16 mm diameter uncoated HYSD Rebar with Parallel Ribs
and Nano modified Cement Polymer Anticorrosive Coated Rebars 29
0
20
40
60
80
100
120
0 0.1 0.2 0.3 0.4 0.5 0.6
Load
in
kN
Slip ( mm)
HYSD Control
HYSD 1 coat
HYSD 2 coat
0
10
20
30
40
50
60
70
80
0 1 2 3 4 5 6
Load
in
kN
Slip ( mm)
HYSD
Control
HYSD 1
coat
HYSD 2
coat
b. Loaded End Behaviour
a. Free End Behaviour

30
Types of Rebar
Load (kN)
Usable Bond
Strength
(N/mm2)
Variation
(%)
0.025m
m FE
slip
0.25 mm
LE slip
Ultimate
load
(kN)
Uncoated rebar – CC 39 32.6 112.61 8.10 -
Single Coated CPAC rebar – CC 37.22 25 105.32 6.21 - 23.33
Double Coated CPAC rebar – CC 34 25.70 129.00 6.39 - 21.11
Table 7 Observation on Bond Strength Test for 16mm Diameter uncoated, single
and double coated nano modified CPAC HYSD rebar with Diamond Ribs

a) Free End Slip Behaviour
31
b) Loaded End Slip Behaviour
Figure (3) Load-Slip Behaviour of 16 mm diameter uncoated HYSD Rebar with Diamond Ribs and
Nano modified Cement Polymer Anticorrosive Coated Rebars

32
Types of Rebar
Load (kN)
Usable Bond
Strength
(N/mm2)
Variation
(%)
0.025m
m FE
slip
0.25 mm
LE slip
Ultimate
load
(kN)
Uncoated rebar – CC 17.91 16.89 32 4.20 -
Single Coated CPAC rebar – CC 23.5 21.5 26 5.34 + 27.14
Double Coated CPAC rebar – CC 19 18.23 25 4.53 + 7.85
Table 8 Observation on Bond Strength Test for 16mm Diameter uncoated, Single
and Double coated nano modified CPAC Mild Steel Rebars

Figure (4) Load-Slip Behaviour of 16 mm diameter uncoated Mild Steel Rebar with Diamond
Ribs and Nano modified Cement Polymer Anticorrosive Coated Rebars
33
a) Free End Slip Behaviour b) Loaded End Slip Behaviour

34
Types of Rebar
Load (kN)
Usable Bond
Strength
(N/mm2)
Variation
(%)
0.025m
m FE
slip
0.25 mm
LE slip
Ultimate
load
(kN)
Mild Steel Bar 17.91 16.89 32 4.2 -
PSWC Bar 33.5 29.75 76.40 7.3 + 73.80
HYSD Bar with Parallel Ribs 37.8 32.6 102 8.10 + 92.85
Table (9) COMPARISON OF PSWC BAR WITH MS REBAR & HYSD REBAR WITH
PARALLEL RIBS AS PER BIS STANDRADS

Figure (5) Load-Slip Behaviour of 16 mm diameter Mild Steel Bar, PSWC Bar with 4 mm
Deformation and 80 mm Pitch Length and HYSD Bar with Parallel Rib Configuration
35

BOND STRENGTH TEST USING BEAM END SPECIMENS
 For the study of bond behaviour of 16 mm Mild steel rebar, PSWC rebar
with 4 mm deformation and 200 mm pitch length and HYSD rebar with
parallel rib configuration.
 Totally 9 beam end specimens were casted three for each category of
rebars.
 The load-slip behaviour was compared with the previously done
researches and analytical comparison was done to access the load-slip
behaviour.
36

Figure (6) Load-Slip Behaviour of 16 mm diameter Mild Steel Bar and HYSD Bar with Parallel
Rib Configuration
37

Figure 6) Load-Slip Behaviour of 16 mm diameter Mild Steel Bar and PSWC Bar with 4 mm
offset and 200 mm Pitch Length
38
PSWC Bar – 4mm
MS Rebar

39
Type of Rebar
Load (KN)
Usable Bond
Strength
(N/mm2)
Variation
(%)
0.025mm FE
slip
0.25mm LE
slip
Ultimate Load
(kN)
MS
Rebar
HYSD
Rebar
Mild Steel Bar 25.19 24.89 32.7 6.18 - - 35.62
PSWC Bar 37.52 36.75 78.40 9.18 +48.54 - 4.37
HYSD Bar with
Parallel Ribs
39.81 38.61 114 9.60 +55.33 -
Table (10) Observation on Bond Strength Test for 16mm Diameter Mild Steel Rebar,
PSWC Rebar and HYSD Rebar with Parallel Ribs

ANLYTICAL INVESTIGATION
40
Figure 6: Cross Section Model for IS Pull-Out
Specimen
Figure 7: Cross Section Model for
ASTM Beam End Specimen

DEFORMATION VALUES FOR DIFFERENT LOAD CONDITIONS BY ANSYS WORKBENCH
41
Figure 8: Deformation for 20 KN Figure 9: Deformation for 25 KN

SHEAR STRESS CONCENTRATION FOR WHOLE BEAM-END MODEL AND ON PSWC
BAR OF 4 MM OFFSET AND 200 MM PITCH LENGTH
42

43
0.219
0.22
0.221
0.222
0.223
0.224
0.225
0.226
0 2 4 6 8 10 12 14
Deflection
(mm)
Offset (mm)
OPTIMISATION OF PSWC BAR

Table (11) Comparison of Analytical and Experimental Results for BIS
Pullout Specimens
Type of Rebar
Offset and Pitch
Experimental Results Analytical Results
Ultimate
Load (kN)
Usable Bond
Strength
(N/mm2)
Ultimate Load
(kN)
Usable Bond
Strength
(N/mm2)
Mild Steel Bar - 32.7 6.18 33 6.91
PSWC Bar 4 mm and 80 mm 78.40 9.18 79 9.37
HYSD Bar with
Parallel Ribs
112 8.10 121 9.71
44

1) There is a marginal increase in usable bond strength and ultimate bond
strength for HYSD diamond rib rebars as compared to HYSD parallel rib
rebars of the order of 6-10%.
2) PSWC bars with 4mm offset, 80mm pitch offered ultimate strength of 76.40 kN
which is 1.4 times more than for mild steel rebars. Also there is a significant
increase in usable bond strength of the order of 70% as compared to mild steel
rebars.
3) Ultimate bond strength of PSWC bars is around 75% greater as compared
to HYSD rebar and the usable bond strength is only 10% less than for
HYSD rebar with parallel ribs.
4) According to BIS 13620:1993, the measured free end slip of coated rebars
shall not be less than 80% of the corresponding bond strength of
uncoated rebars. Both single and double cement polymer anticorrosive
coated rebars satisfy the codal provisions of Indian Standards.
45
CONCLUSIONS

REFRENCES
• Abrams Duff A. (1913),”Test of Bond between steel and concrete”, bulletin no. 71, University of Illinois.
• Ahmed K. Siddiqi Z.A and Yousaf M., (2007),” Slippage of Steel in High and Normal Strength Concrete”,
Pakistan Journal Engineering and Applied Science, Vol. 1, PP.31-39.
• Anil K. Kar. (2014), “C-bar as a Solution to the Problem of Early Distress in Concrete Structures”, Bengal
Engineering and Science University.
• Anil K.Kar and Haji Sheikh Mohammed, M.S.,(2013),“Performance of Concrete Flexural Elements
Reinforced with C-Bars”, The Master Builder, Vol. 14,No. 7,PP 194-200
• ASTM A944-10, “Standard test Method for Comparing Bond Strength of Steel Reinforcing Bars to
Concrete Using Beam-End Specimens”.
• IS 2770:1967 Part 1,”Methods of Testing Bond in Reinforced Concrete Pull-out Test”,Part 1.
• IS 456-2000, “Plain and reinforced concrete code of practice”, Bureau of Indian standard.
• Manoj Kumar (2013), “An Analytical Study on Interaction between C-bar and Concrete under Standard
Pull-out Test Condition”, Indian Institute of Technology Kanpur.
• BARBOSA, M.T.G. Evaluation of the Behavior of the Bond stress in High Strength Concrete. 7th
Symposium on the Utilization of High-strength/ high performance concrete.v.1, pp. 481-494. 2005.
• Abosrra L., Ashour A.F., Youseffi M., “Corrosion of steel reinforcement in concrete of different
compressive strengths,” Construction and Building Materials, Volume 25,Issue 10, October 2011,
Pages 3915-3925.
• Ann Ki Yong, Song Ha-Won, “Chloride threshold level for corrosion of steel in concrete,” Corrosion
Science, Volume 49, Issue 11, November 2007, Pages 4113-4133.
46

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