Experimental Study on Bonding Performance of Basaltic Fiber
Reinforced Polymer and Inorganic Polymer Concrete
Xin Li
1,a
, HaiQin Xu
1,*,b
, YongHao Qian
1,c
, Tao Wang
1,d
, DanDan Xiao
1,e
and XiaoChun Fan
1,e
1
School of Civil Engineering and Architevture,WuHan Technology of University, LuoShi Road 122, WuHan, China
e
1774353675@qq.com,ffxcfree@126.com,
*Corresponding author
TEL +86 13638644921
Keywords: Inorganic polymer concrete, basalt fibre reinforced polymer, bond performance, pull-out test.
Abstract: Inorganic polymer concrete (IPC) and basalt fibre reinforced polymer(BFRP) has good durability. This
paper presents a bond durability test for BFRPbar to the IPC. The test in this article chose BFRP bars in
diameter of 10mm, 12mm and 16mm, with two kinds of IPC in different strength, through experiment, the
bond property between the IPC and BFRP bars is studied systematically. In this paper, the bond-slip curves
of the IPC-BFRP are obtained by the tensile test between them, which proves that they have good bonding
property and provide reference for the application of the IPC-BFRP structure in the engineering.
1 INTRODUCTION
The bond strength between the steel and concrete
plays a key role in their cooperative work [1]. In
response to the requirements of the green building
that the country advocates, the research community
and construction industry have expanded their
horizons to new building materials[2]. In this paper,
the bonding performance between the new concrete-
IPC and the composite bar- BFRP is studied. The
raw material composition of IPC derived from solid
industrial waste is environmentally friendly building
materials. The BFRP raw materials are derived from
natural basalt ore which are not easy to rust. It is a
natural Inorganic non-metallic material. The
structural system composed of the two new materials
can solve the problems of environmental pollution of
reinforced concrete materials and the reduction of
structural mechanical properties caused by steel
corrosion [3].
There are many factors that affect the bond
strength between BFRP and IPC, similar to
reinforced concrete components, mainly by the
following [4-9]: (1) Strength grade of IPC; (2) The
position of BFRP in concrete; (3) When there are
multiple BFRP in a member and they are in a row,
the net distance between the BFRP has an important
influence on the bond strength. The smaller net
distance, the lower bond strength will be. (4)
Thickness of protective layer of IPC; (5) Surface
form and diameter of BFRP; (6) Bond length
between IPC and BFRP, etc. At present, there is still
a lack of in-depth research on the bonding properties
between IPC and BFRP. This article mainly explores
the effect of two different mix ratios of IPC and
BFRP on the Bonding performance. Through the
center pull-out test, the ultimate bond strength of the
test piece and bond stress-slip curve are obtained[5],
to explore the bonding properties between the two.
2 EXPERIMENTAL WORK
2.1 Materials Properties
2.1.1 Inorganic Polymer Concrete
The compressive strengths of Inorganic Polymer
Concrete were determined by using 150mm cube
specimens through Compression test. The concrete
mix design is shown in Table 1. Concrete cube and
pull-out specimens were removed from the moulds
after 24h.And after being cured with water for 28
days, all the specimens and cubes were ready.The28-
day compression strengths of IPC20 was 20.5MPa,
and the 28-day compression strengths of IPC30
was31.3MPa.
Table 1the mix design of IPCkg/m3
Note:In Table 1,the concentration of Sodium hydroxide
solution is 10mol/L,and in Sodium silicate
solution,SiO2/Na2O=2.
2.1.2 BFRP Reinforcing Bars
Three types of BFRP bars with a diameter of 10mm
12mm and 16mmused in this paper were made by
Jiangsu Green Materials Valley New Material T&D
Co., Ltd (GMV). The tested properties of BFRP is
summarized in Table 2.
Table 2 Physical and mechanical properties of BFRP
reinforcing bars
Bar
Type
Diam
eter/
m
Maxim
um
pulling
force/k
N
Ultimate
tensile
strength/
MPa
Average
tensile
Strength/
MPa
79.16 1302
BFRP10 10 77.99 1283 1274
75.16 1236
109.09 1246
BFRP12 12 105.83 1209 1225
106.88 1221
196.11 1260
BFRP16 16 188.94 1214 1234
191.26 1229
2.2 Test Specimens
In accordance with GB50152-9218 Standard
methods for testing of concrete structures, 18 pull-
out specimens were produced[7]. As shown in Fig 1,
BFRP reinforcing bars with a diameter of 10mm
12mm16mm. And two kind of Inorganic Polymer
Concrete were used to test bond strength. The total
length of the BFRP reinforcing bars is 800mm, and
bond length is five times of diameter(5*10mm
5*12mm 5*16mm).The length of free end is
50mm[2].Plastic tubes were adopted to make up un-
bond area. Considering about the poor shear strength
of BFRP bars, steel casing of 300mm length and
resin glue were used to fix the loading end of bars to
prevent the too much power given[10-13].Schematic
diagram of the pull-out specimens are shown in
Fig.2.
Figure1 BFRP reinforcing bars (already fixed)
Figure2Schematic diagram of the pull-out specimens
2.3 Test Setup and Test Method
The tests were carried out with Electro-
hydraulic servo universal testing machine
1000KN/SHT4106-G in Wuhan University of
Technology, Materials Research and Test Centre at a
rate of 1 mm/min. The pull-out specimen was put in
pull-out shelve. Loading statistics were recorded by
Electro-hydraulic servo universal testing machine,
and the displacement on the free end of the BFRP
transducer. The details of pull-out shelve are shown
in bar was measured with a displacement Fig.4.The
pull-out test setup and instrumentation are shown in
Fig.3.
Figure 3:The test equipment. Figure 4: The pull-outshelve.
3 RESULTS AND DISCUSSION
3.1 Mode of Failure
3.1.1 Pull-out Damage
The BFRP were pulled out and damaged in the
specimens numbered B10C20, B10C30 and
B12C30. During the loading process, due to the
chemical bonding force, mechanical anchorage force
of BFRP and the elastic deformation of bars, the
displacement of free end fell behind the loading end.
As the loading continues, the displacement of free
end and the loading end were found to be developing
gradually. When the pull-out force reached its peak,
the pull-out force began to decrease. At this time, the
slip of free end and the load-end developed at about
the same time, but the displacement of free end still
fell behind the load-side’s displacement. Finally, the
displacement of the free-end and the displacement of
the loading end were synchronized, and the chemical
bonding between BFRP and IPC could be declared
invalid.
By observing the extracted bars, it was found
that the cross ribs of BFRP were seriously worn out.
The BFRP of 10 mm diameter were slightly worn
and relatively well-preserved. And there were a
small amount of inorganic polymer concrete chips
between the cross ribs. The pull-out force would be
larger when use BFRP of 12mm diameter, even
leading to the shear failure of the entire cross ribs
and stacking more IPC debris between the cross ribs.
The specific situation is shown in Figure 5.
Figure 5: pull out damage
3.1.2 Splitting Damage
In this test, concrete specimen splitting failure
occurred on the drawing specimens numbered
B12C20, B16C20, and B16C30. During the test
process, as the pulling force increased, the cross ribs
were wear away, the residual ribs piled up to the free
ends, and the hoop stress of IPC was increasing. The
concrete cracked when the concrete's tensile strength
was insufficient to resist the hoop stress. When a
splitting failure occurred, the load dropped sharply
Figure 6: Concrete splitting failures
and the chemical bonding between BFRP and IPC
failed. The specific cracking of each specimen is
shown in Figure 6.
3.2 Bond Strength
This test assumes that the bond stress is distributed
equably along the depth of BFRP, and the bonding
stress between the IPC and BFRP can be calculated
by Equation (1) [10]:
/ 1
In the formula,τis the average bond stress;Fis
the loading force of the testing machine;d is the
basalt bar diameter;l
is the effective bond length.
Table 3 Bond test results after pull-out testing.
Note: 20, 30 represents the design strength of the
IPC, B represents basalt bars, 10, 12 and 16
represent the diameters of the BFRP, and the
specimens with the number B12C20 have one and
the other two specimens of the same group with the
failure modes and bonding. There is a significant
difference in strength and it is determined that the
data is invalid and discarded.
By analyzing the data in the table:
(1)Under the premise that the bond length was five
times the diameter of the reinforced material, the
pullout of the reinforcing material was easy to occur
when the IPC with the strength of 20MPa and BFRP
with the diameter of 10mm work together. When
BFRP with the diameter were 12mm and 16mm,the
concrete splitting failures were easy to occur. When
IPC with the strength of 30 MPa worked together
with basalt reinforcements with diameters of 10 mm
and 12 mm, specimens tended to be pulled out and
broke out. When combined with basalt
reinforcement with the diameter of 16 mm, the
concrete splitting failures were easier to occur.
(2) Comparing the test data of the bond
strengths of B10C20, B12C20and B16C20, the
average bond strength between IPC and 10 mm
BFRP was 14.48 MPa. When diameters of BFRP
increased to 12 mm, the bond strength increased
3.73%, and when the diameter of BFRP increased
to 16 mm, the bond strength decreases by
30.52%.Comparing the test data of the bond
strengths of B10C30, B12C30and B16C30, the
average bond strength between IPC and 10 mm
BFRPwas13.07 MPa. When diameter of BFRP
increased to 12 mm, the bond strength decreased by
14.23%, and when BFRP increased to 16 mm, the
bond strength decreased by 18.06%.
(3)Comparing the test data of the bond strength of
B10C20 and B10C30, the average bond strength of
20MPa IPC and 10mm BFRP was 14.48Mpa.The
bond strength decreases by 9.74%, when the
strength of IPC was increased to 30MPa. The
average bond strength of 20MPa IPC and 12mm
BFRP was 15.02Mpa.When the strength of IPC is
increased to 30MPa, the bond strength is reduced
by 25.37%.And the average bond strength of
20MPa IPC and 16mm BFRPwas10.06Mpa.When
the strength of IPC was increased to 30MPa, the
bond strength is increased by 6.46%.
3.3 Bond Stress-Slip Responses
The BFRP would be stretched during the loading
process, making the sliding of the loading end
inaccurate, so the test adopted a displacement meter
to test the free end displacement, and the
displacement data collected at the free end was used
as the slip value. From the obtained load data, the
bond stress was calculated by formula (1), so we can
draw a more realistic bond stress-slip curve.
aB10C20
bB10C30
cB12C20
dB12C30
eB16C20
fB16C30
Figure 6: Bond stress-slip curves
By analyzing the bond stress-free end slip curve,
wefound:
(1) For the pull-out test specimens with BFRP pulled
out from B10C20, B10C30and B12C30, the bond
slip curve exhibited a cyclic decay pattern. As the
cross ribs of the BFRP were successively damaged
when they were pulled out, the load-displacement
curve presented alternate peaks and valleys, and
showed a gradually decreasing trend. The process of
BFRP and IPC bond-slip: At the initial stage of
loading, the bond between BFRP and IPC was
mainly provided by chemical bonding force. The
duration of this process was short, because the
chemical adhesion force was small. Afterwards,
there was a slight displacement at the free end, and
the chemical bonding force disappears. Then the
pull-out force was provided by the friction force and
the mechanical bite force. And on the slip curve, the
pull-out force and the slip were all increasing,
presenting the certain nonlinearity. As the load and
slip continued to increase, the pull-out force slowly
rose, the displacement increased sharply and the
curve became more nonlinear. The pull-out force
reached the peak and then gradually decreased,
because the ribs of BFRP were worn out. The cross
ribs were destroyed one after the other, because the
cross ribs of BFRP had a certain distance. The peaks
and valleys appeared on the curve in order, and they
appeared cyclically decaying.
(2) For specimens with concrete splitting failure
of B12C20, B16C20 and B16C30, when the pull-out
force gradually increased to reach the first peak, the
concrete was split and broken due to the tensile
strength of the concrete that could not resist the
tensile force. Unlike the specimens with basalt bars
were pulled out, the pull-out force rapidly dropped
after the pull-out force reached the first peak.
Concrete creaked due to insufficient tensile strength
to resist tensile stress in the hoop force. On the
curve, the bond stress quickly disappeared after
reaching the first peak and the test stops.
4 CONCLUSIONS
In this paper, based on 18 pull-out test specimens,
the bonding properties between BFRP and IPC are
experimentally studied. The main conclusions are as
follows:
(1) There are two main failure modes for the BFRP-
IPC pull-out test: BFRP are pulled out and IPC is
split and destroyed .
.
(2) When 20Mpa of IPC works together with BFRP
with the diameter of 12mm or more, it is prone to
occurconcrete splitting damage. When 30MPa of
IPC works together with BFRP with the diameter of
16mm or more, it is prone to occurconcrete splitting
damage.
(3) IPC and BFRP have good bonding properties,
and their bond strengths are between 9.85 MPa and
16.02 MPa.
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