JSCE 令和3年度土木学会全国大会第76回年次学術講演会

第V部門

繊維補強コンクリート（材料）(2)
2021年9月10日(金) 11:10 〜 12:30 V-4 (Room21)[V-405] Influence of Matrix Strength on Bending Behavior of DFRCC
with Bundled Aramid Fiber
Influence of Matrix Strength on Bending Behavior of DFRCC
with Bundled Aramid Fiber*施 豪暉1、王 1、金久保 利之1 （1. 筑波大学）*HAOHUI SHI1, Jin WANG1, Toshiyuki KANAKUBO1 （1. University of Tsukuba）
キーワード：靭性繊維補強セメント複合材料、収束アラミド繊維、モルタル強度、四点曲げ試験
DFRCC, Bundled aramid fiber, Matrix strength, Four-point bending test
This study focuses on the influence of matrix strength on bending behavior of DFRCC with bundledaramid fiber. In this study, matrix strength and volume fraction of fibers are considered as main
parameters. Four-point bending test was conducted to find out the relationship between bending
behavior and the two parameters. It can be clarified from the results that the addition of bundled aramid
fibers significantly improves the ductility of the matrix in bending behavior. As for DFRCC specimens
with different matrix strength, average maximum bending moment increased with increasing ofcompressive strength.

©公益社団法人土木学会

V-405

Japan Society of Civil Engineers 2021 Annual Meeting

Influence of Matrix Strength on Bending Behavior of DFRCC with Bundled Aramid Fiber
筑波大学学生会員 ○Shi Haohui

1. INTRODUCTION
Ductile fiber-reinforced cementitious composite (DFRCC)
is cementitious material in which short discrete fibers witha certain volume fraction are mixing in mortar matrix toimprove brittle behavior of composite especially in tensile
and bending field.
This study focuses on the influence of matrix strength on
bending behavior of DFRCC with bundled aramid fiber. Inthis study, matrix strength and volume fraction of fibers are
considered as variables. Four-point bending test was
conducted to find out the relationship between bending
behavior and the two parameters.
2. EXPERIMENT OVERVIEW
2.1 Material
Three mix proportions of DFRCC applied in this study are
shown in Table 1. Materials in the three mix proportions
are different in the ratio of cement to fly ash to obtain
different target compressive strength. Table 2 shows themechanical properties of bundled aramid fiber used in thisstudy and Fig 1 shows the visual appearance of it.
2.2 Specimen
The main experimental parameters are matrix target
strength (24, 36, 48MPa) and volume fraction of fibers(None, 1%, 2%), so nine series of specimens are
determined for experiments. Bending specimens arerectangular specimens of 100×100×400mm. [1] For eachseries, five bending specimens were manufactured.
2.3 Loading and measurement
Four-point bending test was carried out using a universal
testing machine of 2MN capacity. Image of four-point
bending test is shown in Fig 2. Load was applied to thespecimen on the trisection points of span, and loading
speed was set as 0.5mm/min. Testing area is the constantmoment region of 100mm in length. Two displacementtransducers were set up on compression and tension sidesof testing area. Measurement items for all specimens wereload and the two axial deformations. With the two axial
deformations, curvature can be calculated from dividing
the difference in strains between tension and compression
sides by the vertical distance between the two transducers(=70mm). [1]Keywords
連絡先

学生会員 Wang Jin
正会員 金久保 利之

筑波大学
筑波大学

Table 1. Mix proportions of mortar matrix
SeriesW/BCFAS

Fc240.392

111

Fc360.392

10.43

0.71

Fc480.392

10.110.56

SR

B×C×0.62%

2%※ B=C+FA
W: Water

C: Cement

FA: Fly Ash S: Fine sand

SP: Water reducing agent

SR: Shrinkage reducing agent

Table 2. Mechanical properties of bundled aramid fiber
Diameter

LengthTensile strength

Elastic modulus

(mm)

(mm)

(MPa)

(GPa)

0.5303432

73

Fig 1. Visual appearance of bundled aramid fiber(Unit: mm)
Fig 2. Image of four-point bending test
Table 3. Compressive properties of DFRCC
Compressive strength

Elastic modulus

(MPa)

(GPa)

Fc24-N

20.0

11.2

Fc24-1%

19.4

11.2

Fc24-2%

18.8

10.7

Fc36-N37.1

14.9

Fc36-1%

34.8

15.2

Fc36-2%

35.1

14.5

Fc48-N

52.6

17.4

Fc48-1%

53.7

17.8

Fc48-2%

53.0

17.0Series

EXPERIMENTAL RESULT AND DISCUSSION
3.1 Matrix strength and elastic modulus
3.

Compressive test for cylinder specimens (100×200mm)
was conducted to confirm the compressive strength andDFRCC, Bundled aramid fiber, Matrix strength, Four-point bending test〒305-8573 茨城県つくば市天王台 1-1-1 筑波大学 TEL 029-853-5045

JSCE 令和3年度土木学会全国大会第76回年次学術講演会© Japan Society of Civil Engineers

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Japan Society of Civil Engineers 2021 Annual Meeting

Fc24-N

Fc24-1%

Fc24-2%

Fc36-N

Fc36-1%

Fc36-2%

Fc48-N

Fc48-1%

Fc48-2%

Fig 3. Bending moment - curvature curves (M - φ curves)
Maximum bending moment
Mmax [kN·m]

elastic modulus of DFRCC. Table 3
1.5
FibersCracks distribution
None fiber
1% fibers
lists the compressive properties of2% fibers
None1DFRCC. As reveled by the results,
although experimental strengths
0.51%
were not completely consistent
with target strengths, they showed
012243648602%
obvious difference to each other.
Compressive strength [MPa]3.2 Results of bending test
Fig 4. Relationship between Mmax
Fig 5. Cracks distribution of specimens in Fc36 series
Bending moment - curvature curves
and Compressive strength(M - φ curves) for each series arespecimens increased with increasing of compressive
shown in Fig 3. The specimens, in which the localized
strength and increased more from Fc24 to Fc36 than Fc36
crack opened out of the testing area, are not included in Fig
to Fc48. It should be noticed that obvious dispersion can
3. Bending moment of DFRCC specimens decreased
be detected in Fc48-2% series.
gradually after peak in a wide range, indicating that
4. CONCLUSION
addition of fibers significantly improves the ductility.
▪ Addition of bundled aramid fibers significantly improves
Fig 5 shows the cracks distribution of specimens in Fc36
the ductility of the matrix in bending behavior.
series as representative. It can be seen that specimen▪ As for DFRCC specimens, average maximum bending
without fiber only had one obvious crack in the middle
moment increased with increasing of compressive strength.
range throughout depth, while DFRCC specimens had
ACKNOWLEDGEMENT
plural independent cracks in middle and lower range.
This study was supported by the JSPS KAKENHI Grant
Fig 4 plots the relationship between maximum bending
Number 18H03802.
moment Mmax and compressive strength. Compared withREFERENCES
mortar matrix without fiber, average Mmax of DFRCC[1] JCI-S-003-2007: Method of test for bending moment specimens shows much higher. Average Mmax of DFRCC
curvature curve of FRCC.

JSCE 令和3年度土木学会全国大会第76回年次学術講演会© Japan Society of Civil Engineers- V-405 -