Experiments on Tensile and Shear Characteristics of Amorphous Micro Steel (AMS) Fibre-Reinforced Cementitious Composites
International Journal of Concrete Structures and Materials
Experiments on Tensile and Shear Characteristics of Amorphous Micro Steel (AMS) Fibre-Reinforced Cementitious Composites
Amorphous micro-steel (AMS) fibre made by cooling of liquid pig iron is flexible, light and durable to corrosion, then to be compatible with high flowable and disperable states of mixing as well as high ductile post-cracked performances to apply in fibre-reinforced cementitious composites. In the current research, AMS fibre-reinforced cementitious composites based on cement and alkali-activated ground granulated blast furnace slag mortars were newly manufactured and evaluated for the strength and ductile characteristics mainly by direct tensile and shear transfer tests in the variation in the volume of AMS fibres with two different lengths of 15.0 and 30.0 mm. As a result, it was found that 1.0-1.25% fibre volume fractions were recommendable for AMS fibre-reinforced cementitious composites to maximize direct tensile strength, ductile tensile strain, and shear strength of the composites. However, a further fraction of AMS fibre lowered these mechanical characteristics. Simultaneously, it could be said that AMS fibre-reinforced cementitious composites exhibited up to about 3.7 times higher in direct tensile strength and up to 2.3 times higher in shear strength, compared to AMS fibre-free specimens.
fibre-reinforced cementitious composites; amorphous micro-steel (AMS) fibre; crack control; tensile strength; shear transfer
Attempts to utilize fibre cementitious or concrete
composites mixed with metallic or non-metallic fibres had been
greatly made in fields of high rise building and infra
structures in order to enhance additional requirements of high
ductility, performance and durability
Darwish 1987; Ashour et al. 1992; De Hanai and Holanda 2008;
Fischer and Li 2003; Kim et al. 2009; Lee et al. 2012; Choi
et al. 2014)
. For fibre-reinforced cementitious composites,
non-metallic fibres such as synthetic fibres were used to
mainly develop high ductile characteristics after cracking,
with no improvement of strength, known as engineered
cementitious composites (ECC) or strain-hardening
cementitious composites (SHCC)
(Fischer and Li 2003; Lee et al.
2012; Choi et al. 2014; Cho et al. 2012; Kim et al. 2014)
the other hand, steel fibres are often used to mix in concrete
or cementitious composites to refine their brittle
characteristics by enhancing tensile and shear strength
and Darwish 1987; Ashour et al. 1992; De Hanai and
Holanda 2008; O¨zg u¨r and Khaled 2009; O¨zcan et al. 2009;
Lim and Hong 2016; Lu et al. 2016)
Most of steel products used in construction fields such as
deformed reinforcing bars, steel fibres, and steel plates, etc.,
in general, are crystalline metals, of which properties are
mainly characterized by adjusting the cooling speed after
crystalline metals are liquefied under high temperature. A
crystal in metal is formed when liquid metal is cooled slowly
at thousands of degrees per second
(Won et al. 2012; Seo
. These crystalline steels are basically an anisotropic
material, consisting of regular arrays of atoms, so that their
mechanical characteristics are dependent on crystal
directions, such as in exhibiting the modulus of elasticity,
electrical and heat conductivities, and refractivity.
In the manufacturing process, steel fibres produced from
wires are subjected to a repeated heating and cooling process
of lengthening and thinning, then to achieve suitable shape,
yield and rupture strength as well as elastic modulus.
Considering in fibre-reinforced cementitious composites, steel
fibre is, however, susceptible to corrosion in a humid
atmospheric condition. Moreover, high level of the specific
gravity may lower dispersion of steel fibres in fresh binders;
a suitable quality of fibre-reinforced cementitious
composites may not be achieved
(Won et al. 2012; Morga et al.
1999; Yoo et al. 2016)
Amorphous micro-steel is fundamentally different in the
manufacturing process that cools liquid pig iron at the
bottom of a furnace under fast rotation and do not make
crystalline grain boundaries in the metal, when the metal
liquid is cooled rapidly above 105 K/s
(Won et al. 2012; Seo
. Therefore, the micro-steel is a pure isotropic as
independent to material directions and an amorphous metal
as exhibiting liquid characteristics in solid, called as a
liquid metal. Amorphous micro-steel has not only a superb
strength and toughness with the relatively low specific
gravity in mechanical characteristics, but also has
distinguished durability to resist corrosion in humidity, acid and
(Won et al. 2012; Seo 2006)
researchers attempted to evaluate mechanical properties of
mortar or concrete including AMS fibres
Chermant 1999; Won et al. 2013; Dinh et al. 2016; Yoo
et al. 2016)
In this study, the feasibility of a new micro-steel fibre (i.e.
amorphous micro-steel fibre made by cooling of liquid pig
iron) reinforced cementitious composite based on cement
and alkali-activated ground granulated blast furnace slag
(GGBS) mortars was experimentally assessed for the
strength and ductile characteristics mainly by direct tensile
and shear transfer tests in the variation in the volume of
AMS fibres with two different lengths of 15.0 and 30.0 mm.
In addition to optimize the volume of the steel fibre in the
mix, the slump flow, the compressive strength, the direct
tensile behavior, and the shear transfer were examined.
2. Amorphous Micro-Steel Fibre-Reinforced
2.1 Manufacturing of Fibre-Reinforced
Amorphous micro-steel (AMS) fibre can be easily and quickly
manufactured by cutting immediately after a rapid cooling
process of the amorphous liquid metal, as shown in Fig. 1. Two
different AMS fibres (thickness 9 width 9 length; 0.028 9
1.0 9 15.0 mm and 0.028 9 1.0 9 30.0 mm) were well
dispersed mixed, respectively in mortar of which ratio for ordinary
Portland cement (OPC), ground granulated blast furnace slag
(GGBS), silica sand, and water was 1.25: 0.31: 1.00: 1.19 by
mass. The specific gravity of the steel fibre was equated to
7.0–7.2, and C 1600 MPa in the tensile strength.
Simultaneously the oxide composition for OPC and GGBS is given in
Table 1. The fraction of AMS fibre was in the range of 0, 0.5,
0.75, 1.00, 1.25 and 1.50% by volume of the mortar. To manifest
uniform fibre dispersion, the viscosity modifying admixture
(VMA) was added in the mix to achieve adequate rheological
(Cho et al., 2012)
. Then, slump flow was measured
immediately after mixing mortar containing the AMS fibre, and
the compressive, tensile and shear strengths were measured after
28 days of curing in water at 23 ± 3 C.
2.2 Measurement of Slump and Mechanical
The flow and mechanical characteristics of fresh and
hardened AMS fibre composite were tested and measured
varying with the fibre volume(0, 0.5, 0.75, 1.00, 1.25 and
1.50%) for two different fibre length of L = 15 mm and
L = 30 mm. The fluidity of mortar containing AMS fibre
was measured immediately after mixing, casting in a cone
and removing the cone, of which the taper-shaped margin
was Ø100 9 Ø200 9 300 mm
(KS F 2402 2007)
compressive strength was measured by a 50 mm cube
specimen for two specimens for each mix, according to
Simultaneously the schematic of specimens for measuring
the tensile strength and strain as well as shear strength is
given in Fig. 2
(Kim et al. 2007; Mattock and Hawkins
. The specimens for the direct tensile test in Fig. 3
were made to have two dog-bone shapes in both ends, as
already shown elsewhere (Kim et al. 2007), to avoid
fractures outside the gage length. As shown in Fig. 3, the
elongation was measured by two linear variable differential
transducers (LVDT) attached to both sides of the center of
the specimen with a gage length of 150 mm as referred to
the distance. The test was monitored under displacement
control with a loading speed of 0.1 mm/min. From the direct
tensile test, the tensile stress–strain curves were measured
additionally with tensile strength and ultimate ductile tensile
strain for two specimens for each mix.
For measuring the shear strength, dimension of specimen for
shear transfer was 240 9 150 9 80 mm. To measure shear
transfer across a plane in the composite, as shown in Fig. 4, by
applying a compressive load, the test unit was designed to fail
in shear on the shear plane of 50 9 80 mm in the specimen. A
shear crack was induced by increasing the axial load of the
UTM and the shear strength was measured at the moment of
failure caused by shear crack
(Mattock and Hawkins 1972)
3. Characteristics of Slump Flow and Compressive Strength
The slump flow of mortar containing AMS fibre was
measured as given in Fig. 5, together with a photo of
measurement. It was evident that an increase in the volume of
AMS fibre resulted in a decrease in the fluidity, irrespective
of the length of the fibre. Fibre-free mortar had the slump
flow, accounting for about 680 mm, whilst the fluidity was
dramatically reduced by the AMS fibre. It may suggest that
overwhelming amount of fibre is limited due to clash
between the fluidity and strength development.
0.50 0.75 1.00
Volume of steel fibre (%)
The compressive strength of mortar containing AMS fibre
is given in Fig. 6. It was evident that the fibre might not
benefit in enhancing the strength of concrete; there was only,
in fact, a reduction of the compressive strength in the mix
containing 30 mm long AMS fibre. In particular, the
compressive strength at 1.5% of AMS fibre was equated to
27.7 MPa, whilst fibre-free mortar indicated 33.9 MPa. The
variation in the compressive strength was again observed for
15 mm long AMS fibre: the range of the compressive
strength was 32.3–34.8 MPa. Substantially, it seemed that
no benefit in raising or at least sustaining the compressive
strength was gained by AMS fibre in concrete. Above the
fibre volume of 0.75%, the compressive strength tend to
reduce with increase of the fibre volume fraction which is
mainly caused by insufficient fibre dispersion as observed in
(Yoo and Banthia 2017)
4. Test and Discussions on Direct Tensile
After curing of 28 days, tensile behaviors of hardened
AMS fibre composite were examined and test results were
presented by tensile stress–strain curves as given in Fig. 7.
Non-fibre mortar and AMS fibre-reinforced composite with
a fibre volume of 0.5% were exempt from the direct tensile
test due to a very high level of the brittleness in tension. In
preliminary test, the tensile stress had been sharply dropped
after the initial crack was generated when the tensile strain
ranged from 0.22 to 0.23%. All specimens exhibit apparent
multiple cracking patterns accompanying tensile strain
softening and ductile behaviors with strain capacities
ranging from 0.57 to nearly 0.75%. These ductile characteristics
remain much higher than that in normal concrete and
conventional FRC composites.
The tensile strength and strain simultaneously measured
for each mixture are given in Figs. 8 and 9, respectively. It is
clearly shown that an increase in the volume of the AMS
fibre in mixture resulted in a mostly linear increase in the
tensile strength, irrespective of the length of AMS fibre. The
tensile strength of non-fibre mixture was equated to about
1.32 MPa, while the tensile strength of AMS fibre mixtures
with the fibre volume of 1.0, 1.25 and 1.50% exceeded
4.0 MPa. Even with a lower volume of AMS fibre (i.e. 0.50
and 0.75%) the tensile strength was in the range of
2.46–3.57 MPa. When it comes to the tensile strain, it is also
observed that an increase in the volume of AMS fibre in the
mixture resulted in an increase in the tensile strain. In
particular, with up to 0.75% of the AMS fibre in volume, the
tensile strain was significantly increased by the AMS fibre,
which was subsequently marginal in the variation in the
strain, ranging from 0.57 to 0.75%. AMS fibre-reinforced
cementitious composites may represent a post-cracked
ductile strain in direct tensile test, which could not be observed
in fibre-free concrete
(Batson et al. 1972; Shah 1980)
However the ductile capacity of AMS fibre-reinforced
cementitious composites was reduced for ECC and SHCC
mixes, imposing high ductile and strain-hardening
characteristics in direct tensile post-cracked region as the maximum
tensile strain was above 2.0%
(Fischer and Li 2003; Lee
et al. 2012; Choi et al. 2014; Cho et al. 2012)
. AMS fibres in
cementitious mixture were expected to be fracture before
complete pullout as shown in Fig. 10. This would cause a
lower post-peak ductility compared to PVA fibres with a
When the ECC or/and SHCC were manufactured to mix
PVA fibres into cementitious composites about 1.5–3.0% in
volume of the mix, the tensile strength was not much
(Fischer and Li 2003; Lee et al. 2012; Choi et al.
2014; Cho et al. 2012)
. From observations of current direct
tensile test, it was supposed that AMS fibre-reinforced
cementitious composites had ambivalent post-cracked tensile
characteristics between steel fibre reinforced concrete and
ECC mixture. For ductile post-cracked tensile strain
capacities, the AMS fibre cementitious composite was superior to
steel fibre reinforced concrete, but was inferior to ECC or
SHCC mixtures, whilst the AMS fibre-reinforced
cementitious composites could greatly enhance tensile strength,
which cannot be observed in ECC or SHCC mixtures.
Considering the fibre dispersion, mixtures at more than 1.5%
fibre volume fraction were not recommendable to increase
direct tensile strength as well as improve deformation
5. Test and Discussions on Shear Transfer
After curing of 28 days, shear transfer capacity was
examined to measure the shear strength. The shear crack was
observed for all cases, as given in Fig. 11, together with the
shear strength. It was clearly observed that an increase in the
AMS fibre in the mix resulted in an increase in the shear
strength, up to 1.25% of the AMS fibre in volume,
irrespective of the length of fibre. In fact, the shear strength of
the mixture with 1.25% of fibre in volume accounted for
11.77–11.20 MPa, while with 1.50% the shear strength
ranged 9.30–9.77 MPa. The variation of shear strength for
varying fibre contents was manifested as observed in a series
of current test that AMS fibres mixed into cementitious
composites were so efficient to promote the shear capacity of
cementitious composites by suitable fibre contents. Mixtures
of AMS fibre-reinforced cementitious composites exhibited
up to 2.22 times and 2.35 times higher the average
maximum shear strength than the mixture of non-fibre mortar, for
the fibre length of 15 mm and 30 mm, respectively.
For mixtures with less than 1.25% fibre volume fraction,
the shear strength was gradually increased according to the
increase of fibre volume fraction because AMS fibres could
be suitably dispersed into the cementitious mixture with
below the fibre contents. A reduction in the shear strength
with 1.50% fibre volume fraction was presumably due to a
poor dispersion of fibres, which might get tangled and made
fibre balls within cementitious mixtures. It could be
commented from experiments that 1.0–1.25% fibre volume
fractions were suitable to improve shear transfer capacity in
AMS fibre-reinforced cementitious composites with the fibre
length of 15 and 30 mm, and the mixtures with 1.25% fibre
volume fraction could exhibit most excellent to develop
shear transfer capacities in mixtures.
In the present study, a series of experimental programs was
investigated to establish the feasibility of developing a new
micro-steel fibre cementitious composite using OPC and
GGBS mixing mortar and amorphous micro-steel fibres with
Fig. 10 Fracture of fibres in tensile failure of AMS fibre
Fig. 8 Tensile strength of mortar containing steel fibre with
the length of fibre together with a photo of tensile
cracking after the test (Photo scale as a real length of
Fig. 9 Tensile strain of mortar containing steel fibre with the
length of fibre.
the length of 15 mm or 30 mm at 0.5–1.5% in volume, and
the followings were concluded.
The flexible, light weighted properties of amorphous
micro-steel fibres could allow excellent in flowable and
disperable states of mixing with cementitious composites.
The actual slump flow measured immediately after mixing
was about 640 mm, as meeting the flowable workability for
fresh concrete. It was increased the tensile strain and shear
transfer strength of AMS fibre-reinforced cementitious
composites by fiber bridging effects. The fibre dispersion
seemed poor at exceeding 1.5% of AMS fibre in volume
rather than lower values: the shear strength was adversely
reduced at 1.5% of AMS fibre than at 1.25%. Moreover, the
compressive strength seemed not affected by the fibre,
Fig. 11 Shear strength of mortar containing steel fibre
depending on the length of the fibre together with
an example of shear crack.
whereas an increase in the fibre in the mix resulted in an
increase in the tensile strength.
AMS fibre-reinforced cementitious composites had
ambivalent post-cracked tensile characteristics between steel
fibre reinforced concrete and ECC mixtures. For high ductile
post-cracked tensile strain capacities, AMS fibre-reinforced
cementitious composites was superior to steel fibre
reinforced concrete but was inferior to ECC or SHCC mixtures.
For the tensile strength, the ultimate tensile strength of AMS
fibre-reinforced cementitious composites could be greatly
enhanced varying with the fibre contents, as also observed in
steel fibre reinforced concrete, but these phenomena of
tensile strength enhancement cannot be fundamentally
observed in ECC or SHCC mix.
This research was supported by a Grant
(17RDRP-B07626804) from Regional Development Research Program funded
by Ministry of Land, Infrastructures, and Transport of
Korean government, and supported by research fund from
Chosun University, 2015.
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Ashour , S. A. , Hyasanain , G. S. , & Wafa , F. F. ( 1992 ). Shear behavior of high-strength fiber-reinforced concrete beans without stirrups . American Concrete Institute , 94 , 68 - 76 .
ASTM. ( 2007 ). Standard test method for compressive strength of hydraulic cement mortars (using 50 mm [2 in.] cube specimens), ASTM C109/C109 M-07 .
Batson , G. , Jenkins , E. , & Spatnet , R. ( 1972 ). Steel fibers as shear reinforcement in beams . American Concrete Institute, 69 , 640 - 644 .
Cho , C. G. , Kim , Y. Y. , Feo , L. , & Hui , D. ( 2012 ). Cyclic responses of reinforced concrete composite columns strengthened in the plastic hinge region by HPFRC mortar . Composite Structures , 94 , 2246 - 2253 .
Choi , W. C. , Yun , H. D. , Cho , C. G. , & Feo , L. ( 2014 ). Attempts to apply high performance fiber-reinforced cement composite (HPFRCC) to infrastructures in South Korea . Composite Structures , 109 , 211 - 223 .
De Hanai , J. B. , & Holanda , K. M. A. ( 2008 ). Similarities between punching and shear strength of steel fiber reinforced concrete (SFRC) slabs and beams . IBRACON , 1 , 1 - 16 .
Dinh , N. H. , Choi , K. K. , & Kim , H. S. ( 2016 ). Mechanical properties and modeling of amorphous metallic fiber reinforced concrete in compression . International Journal of Concrete Structures and Materials , 10 ( 2 ), 221 - 236 .
Fischer , G. , & Li , V. C. ( 2003 ). Design of engineered cementitious composites (ECC) for processing and workability requirement . Portland, Proceedings of BMC , 7 , 29 - 36 .
Kim , J. K. , Kim , J. S. , Ha , G. J. , & Kim , Y. Y. ( 2007 ). Tensile and fiber dispersion performance of ECC (engineered cementitious composites) produced with ground granulated blast furnace slag . Cement and Concrete Research , 37 ( 7 ), 1096 - 1105 .
Kim , Y. Y. , Lee , B. Y. , Bang , J. W. , Han, B. C. , Feo , L. , & Cho , C. G. ( 2014 ). Flexural performance of reinforced concrete beams strengthened with strain-hardening cementitious composite and high strength reinforcing steel bar . Composites: Part B , 56 , 512 - 519 .
Kim , D. J. , Naaman , A. E. , & El-Tawil , S. ( 2009 ). High performance fiber reinforced cement composites with innovative slip hardening twisted steel fibers . International Journal of Concrete Structures and Materials , 3 ( 2 ), 119 - 126 .
KS F 2402 . ( 2007 ). Method of test for slump of concrete, Korea Standard Association .
Lee , B. Y. , Cho , C. G. , Lim , H. J. , Song , J. K. , Yang , K. H. , & Li , V. C. ( 2012 ). Strain hardening fiber reinforced alkaliactivated mortar-A feasibility study . Construction and Building Materials , 37 , 15 - 20 .
Li , V. C. , Mishra , D. K. , & Wu , C. ( 1995 ). Matrix design for pseudo strain-hardening fiber reinforced cementitious composites . Materials and Structures , 28 ( 183 ), 586 - 595 .
Lim , W. Y. , & Hong , S. G. ( 2016 ). Shear tests for ultra-high performance fiber reinforced concrete (UHPFRC) beams with shear reinforcement . International Journal of Concrete Structures and Materials , 10 ( 2 ), 177 - 188 .
Lu , L. , Tadepalli , P. R. , Mo , Y. L. , & Hsu , T. T. C. ( 2016 ). Simulation of prestressed steel fiber concrete beams subjected to shear . International Journal of Concrete Structures and Materials , 10 ( 3 ), 297 - 306 .
Mattock , A. H. , & Hawkins , N. M. ( 1972 ). Shear transfer in reinforced concrete-Recent research . PCI Journal , 17 ( 2 ), 55 - 75 .
Morga , D.R. , Heere , R. , McAskill , N. , & Chan , C. ( 1999 ). Comparative evaluation of systemductility of mesh and fibre reinforced shotcretes . In: Engineering foundation, New York sponsored conference shotcrete for underground support VIII campus do Jordao (pp. 1 - 23 ), Brazil.
Narayanan , R. , & Darwish , I. Y. S. ( 1987 ). Use of steel fibers as shear reinforcement . American Concrete Institute , 84 , 216 - 227 .
O ¨zcan , D. M. , Bayraktar , A. , Sahin , A. , Haktanir , T. , & Tu¨rker, T. ( 2009 ). Experimental and finite element analysis on the steel fiber-reinforced concrete(SFRC) beams ultimate behavior . Construction and Building Materials , 23 ( 2 ), 1064 - 1077 .
O¨zg u¨r, E., & Khaled , M. ( 2009 ). Effects of limestone crusher dust and steel fibers on concrete . Construction and Building Materials , 23 ( 2 ), 981 - 988 .
Redon , C. , & Chermant , J. L. ( 1999 ). Damage mechanics applied to concrete reinforced with amorphous cast iron fibers, concrete subjected to compression . Cement & Concrete Composites , 21 ( 3 ), 197 - 204 .
Seo , Y. S. ( 2006 ). Materials for machine (pp. 359 - 361 ), Gijeon.
Shah , S. P. ( 1980 ). Static and fatigue properties of concrete beams reinforced with continuous bars with fibers . American Concrete Institute , 77 , 36 - 43 .
Won , J. P. , Hong , B. T. , Choi , T. J. , Lee , S. J. , & Kang , J. W. ( 2012 ). Flexural behavior of amorphous micro-steel fibrereinforced cement composites . Composite Structures , 94 , 1443 - 1449 .
Won , J. P. , Hong , B. T. , Lee , S. J. , & Choi , S. J. ( 2013 ). Bonding properties of amorphous micro-steel fibre-reinforced cementitious composites . Composite Structures , 102 , 101 - 109 .
Yoo , D. Y. , & Banthia , N. ( 2017 ). Experimental and numerical analysis of the flexural response of amorphous metallic fiber reinforced concrete . Materials and Structures , 50 ( 1 ), 64 - 77 .
Yoo , D. Y. , Banthia , N. , Yang , J. M. , & Yoon , Y. S. ( 2016 ). Size effect in normal- and high- strength amorphous metallic and steel fiber reinforced concrete beams . Construction and Building Materials , 121 , 676 - 685 .
Yoo , D. Y. , & Yoon , Y. S. ( 2016 ). A review on structural behavior, design, and application of ultra-high-performance fiber-reinforced concrete . International Journal of Concrete Structures and Materials , 10 ( 2 ), 125 - 142 .