U.S. patent application number 15/531501 was filed with the patent office on 2017-11-30 for fiber material for cement reinforcement.
This patent application is currently assigned to TEIJIN LIMITED. The applicant listed for this patent is TEIJIN LIMITED. Invention is credited to Takeya DEI, Shuhei OKAMURA, Shintaro SHIMADA, Akira TERAOKA.
Application Number | 20170342654 15/531501 |
Document ID | / |
Family ID | 56416982 |
Filed Date | 2017-11-30 |
United States Patent
Application |
20170342654 |
Kind Code |
A1 |
OKAMURA; Shuhei ; et
al. |
November 30, 2017 |
FIBER MATERIAL FOR CEMENT REINFORCEMENT
Abstract
Provided is a fiber material for cement reinforcement,
configured such that a resin A containing an isocyanate compound as
a constituent component is present inside a fiber bundled body, and
a resin B containing an epoxy resin as a constituent component is
present on a surface of the fiber bundled body. Further, it is
preferable that the resin A contains a polyol or an epoxy compound
as a constituent component in addition to the isocyanate compound,
the resin B contains an acrylic-modified epoxy resin or a
bisphenol-A epoxy resin as a main component, the fiber bundled body
has a tensile strength of 7 cN/dtex or more, and the fiber bundled
body includes 50 to 3,000 single fibers. The invention is also
addressed to a concrete or mortar molded article using the above
fiber material for reinforcement.
Inventors: |
OKAMURA; Shuhei; (Osaka,
JP) ; SHIMADA; Shintaro; (Osaka, JP) ;
TERAOKA; Akira; (Osaka, JP) ; DEI; Takeya;
(Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TEIJIN LIMITED |
Osaka-shi, Osaka |
|
JP |
|
|
Assignee: |
TEIJIN LIMITED
Osaka-shi, Osaka
JP
|
Family ID: |
56416982 |
Appl. No.: |
15/531501 |
Filed: |
January 14, 2016 |
PCT Filed: |
January 14, 2016 |
PCT NO: |
PCT/JP2016/050901 |
371 Date: |
May 30, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 20/1037 20130101;
C04B 28/02 20130101; D06M 15/55 20130101; D06M 13/395 20130101;
C04B 18/022 20130101; C04B 14/38 20130101; C04B 16/0675 20130101;
C04B 18/022 20130101; C04B 16/06 20130101; C04B 20/1037 20130101;
C04B 28/02 20130101; C04B 18/022 20130101 |
International
Class: |
D06M 15/55 20060101
D06M015/55; C04B 20/10 20060101 C04B020/10; C04B 16/06 20060101
C04B016/06; D06M 13/395 20060101 D06M013/395; C04B 14/38 20060101
C04B014/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2015 |
JP |
2015-007728 |
Claims
1. A fiber material for cement reinforcement, characterized in that
a resin A containing an isocyanate compound as a constituent
component is present inside a fiber bundled body, and a resin B
containing an epoxy resin as a constituent component is present on
a surface of the fiber bundled body.
2. The fiber material for cement reinforcement according to claim
1, wherein the resin A contains a polyol or an epoxy compound as a
constituent component in addition to the isocyanate compound.
3. The fiber material for cement reinforcement according to claim
1, wherein the resin B contains an acrylic-modified epoxy resin or
a bisphenol-A epoxy resin as a main component.
4. The material for cement reinforcement according to claim 1,
wherein the isocyanate compound in the resin A is a blocked
isocyanate.
5. The fiber material for cement reinforcement according to claim
1, wherein the fiber bundled body has a tensile strength of 7
cN/dtex or more.
6. The fiber material for cement reinforcement according to claim
1, wherein the fiber bundled body includes 50 to 3,000 single
fibers.
7. A concrete or mortar formed body comprising the fiber material
for cement reinforcement according to claim 1.
8. A method for producing a concrete or mortar formed body
comprising the fiber material for cement reinforcement according to
claim 1 and having a water/binder ratio of 40% or less at the time
of kneading.
9. The fiber material for cement reinforcement according to claim
2, wherein the resin B contains an acrylic-modified epoxy resin or
a bisphenol-A epoxy resin as a main component.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fiber material suitable
for cement reinforcement. It more specifically relates to a fiber
material for cement reinforcement, which is optimal for the
production of concrete, mortar, and the like.
BACKGROUND ART
[0002] Concrete or mortar formed products containing cement as a
main component have compressive strength, durability,
non-flammability, and like excellent characteristics and are also
inexpensive, and thus have been abundantly used in the
architectural and civil engineering fields. However, these formed
products have drawbacks in that their physical properties are
basically brittle even when aggregates such as sand and gravel are
contained, and they are easily cracked or damaged, for example,
upon application of a stress, such as pulling, bending, or
flection.
[0003] Accordingly, in order to compensate for these drawbacks, it
has been considered to use fibrous materials such as asbestos,
glass fibers, steel fibers, and synthetic fibers as reinforcing
materials in addition to various conventional aggregates, thereby
improving the performance of a formed product. By using a fibrous
reinforcing material, the mechanical characteristics, such as
bending strength and bending toughness, of a cement formed body
made of cement paste, mortar, concrete, or the like are
significantly improved.
[0004] However, even in the case where such fibers for
reinforcement are used, there have been problems in that when the
fibers are not sufficiently dispersed in concrete or the like, or
the fibers are entangled with each other during stirring, resulting
in the formation of fiber agglomerates, the reinforcing effect is
not sufficiently exhibited. Thus, in order to enhance the
dispersibility of fibers, it has been considered to use a
monofilament-type fiber having a large fiber diameter. However, in
this case, there has been a problem in that the strength per fiber
thickness decreases.
[0005] Then, it has been considered to employ thick monofilaments.
In addition, in place of the conventional reinforcement with thin
single fibers (filaments) that are hard to disperse, a method in
which a fiber formed of a large number of thin filaments
(multifilament) is bundled with a resin, and the fiber bundle is
cut and used as a reinforcing material, has been considered.
[0006] For example, PTL 1 discloses a method in which non-volatile
oil is attached to fibers bundled with a resin, thereby enhancing
the cohesion of fibers. However, because of the attachment of oil
to the fiber surface, although the cohesion is excellent, the
interfacial attachment strength between cement mortar or concrete
and fibers tends to rather decrease.
[0007] In addition, PTL 2 discloses a reinforcing material obtained
by bundling fibers with a carboxyl-group-containing
acrylic-modified resin, thereby maintaining relatively excellent
cohesion in cement mortar. However, although a
carboxyl-group-containing acrylic-modified resin has high affinity
for cement, it has been difficult to enhance the cohesive strength
of the resin layer present on the adhesion interface. In addition,
there has been a problem in that in the case where a
high-molecular-weight acrylic-modified resin having high cohesive
strength is used, the resin is hard to penetrate the inside of the
fiber bundle, and, as a result, a fiber bundle with high cohesion
cannot be obtained.
[0008] These problems are particularly prominent in the case where
the mortar or concrete to be reinforced has high physical
properties, and the material viscosity at the time of kneading is
high, or in the case where the shear force at the time of kneading
is high, such as the case where the proportion of water or a binder
is small at the time of kneading. Accordingly, it is difficult to
maintain the cohesion of the fiber bundle, resulting in a problem
in that the fresh fluidity decreases during the process, or the
reinforcing effect in terms of bending toughness, etc.,
decreases.
[0009] PTL 1: JP-A-2007-131464
[0010] PTL 2: JP-A-2012-25603
SUMMARY OF INVENTION
Technical Problem
[0011] An object of the invention is to provide a fiber material
for cement reinforcement having high cohesion and an excellent
reinforcing effect, and particularly to provide a fiber material
for cement reinforcement having an excellent reinforcing effect on
high-viscosity concrete or mortar.
Solution to Problem
[0012] The fiber material for cement reinforcement of the invention
is characterized in that a resin A containing an isocyanate
compound as a constituent component is present inside a fiber
bundled body, and a resin B containing an epoxy resin as a
constituent component is present on a surface of the fiber bundled
body.
[0013] Further, it is preferable that the resin A contains a polyol
or an epoxy compound as a constituent component in addition to the
isocyanate compound, the resin B contains an acrylic-modified epoxy
resin or a bisphenol-A epoxy resin as a main component, and the
isocyanate compound in the resin A is a blocked isocyanate
compound. In addition, it is preferable that the fiber bundled body
has a tensile strength of 7 cN/dtex or more, and the fiber bundled
body includes 50 to 3,000 single fibers.
[0014] The invention also encompasses a concrete or mortar formed
body containing the fiber material for cement reinforcement of the
invention described above, which preferably further contains
aggregates. Then, it is preferable that a method for producing such
a concrete or mortar formed body is a production method in which
the fiber material for cement reinforcement of the invention
described above is contained, and the water/binder ratio at the
time of kneading is 45% or less.
Advantageous Effects of Invention
[0015] According to the invention, a fiber material for cement
reinforcement having high cohesion and an excellent reinforcing
effect, particularly a fiber material for cement reinforcement
having an excellent reinforcing effect on high-viscosity concrete
or mortar, is provided.
DESCRIPTION OF EMBODIMENTS
[0016] The invention will be described in detail hereinafter.
[0017] The fiber material for cement reinforcement of the invention
is a reinforcing material configured such that a resin A containing
an isocyanate compound as a constituent component is present inside
a fiber bundled body, and a resin B containing an epoxy resin as a
constituent component is present on a surface of the fiber bundled
body.
[0018] The fiber bundled body used for such a fiber material for
cement reinforcement of the invention is not particularly limited
as long as it is a fibrous material (multifilament) formed of a
large number of single fibers (monofilaments) bundled, and various
inorganic fibers and organic fibers (organic synthetic fiber) are
usable.
[0019] More specifically, examples of fibers used for the fiber
bundled body include inorganic fibers, such as carbon fibers, glass
fibers, basalt fibers, steel fibers, ceramic fibers, and asbestos
fibers, and organic fibers, such as aromatic polyamide fibers
(hereinafter referred to as aramid fibers), vinylon fibers,
polypropylene fibers, polyethylene fibers, polyarylate fibers,
polybenzoxazole (PBO) fibers, nylon fibers, polyester fibers,
acrylic fibers, vinyl chloride fibers, polyketone fibers, cellulose
fibers, and pulp fibers. These fibers maybe used alone or in
combination of two or more kinds.
[0020] Further, it is preferable that the fiber used for the fiber
material for cement reinforcement of the invention is a fiber that
undergoes less degradation in an alkali. As inorganic fibers,
carbon fibers, basalt fibers, and the like are preferable. As
organic fibers, aramid fibers (aromatic polyamide fibers), vinylon
fibers, polyethylene fibers, polypropylene fibers, and the like are
preferable. It is more preferable that carbon fibers or aramid
fibers having a high reinforcing effect in terms of bending
toughness, etc., are used to form a fiber bundle.
[0021] Meanwhile, it is also preferable that the fiber used in the
invention is an organic fiber using a resin produced using an
organic polymer as a starting material. In the case where such an
organic fiber is used for reinforcement, the fiber has excellent
flexibility and is resistant to bending during the process, and
thus is useful. In particular, aramid fibers, vinylon fibers,
polyethylene fibers, polypropylene fibers, and the like, which are
high-strength organic fibers, are preferable. This is because such
an organic fiber undergoes less breakage during kneading or less
strength deterioration due to corrosion or the like in concrete,
eventually exhibiting an excellent reinforcing effect on a cement
material. In order to enhance the strength of a fiber, in addition
to its molecular structure, it is preferable to increase its
molecular weight. For example, in the case of a polyethylene fiber,
it is preferable use ultra high-molecular-weight polyethylene.
[0022] Among them, as the fiber used in the invention,
comprehensively in terms of strength, flexibility, chemical
resistance, and the like, para-type aramid fibers such as
polyparaphenylene terephthalamide are preferable. Further, among
such aramid fibers, copolymerized aramid fibers have particularly
excellent alkali resistance and thus are particularly preferably
used. As a specific example, a
copolyparaphenylene-3,4'-oxydiphenylene-terephthalamide fiber,
which is a copolymerized para-type aramid fiber, has a high
reinforcing effect in cement as compared with other fibers and thus
is preferable. Then, it is preferable that when the fiber is
allowed to stand in a strong-alkali atmosphere at high temperatures
and high pressures for a long period of time, its mechanical
characteristics are not significantly degraded. Specifically, it is
preferable that the strength retention of the fiber in steam curing
at high temperatures and high pressures, for example, under
conditions of 120.degree. C., saturation water vapor, and 100
hours, is as high as 70% or more. Further, it is preferable that
the fiber has a strength retention of 90 to 100%.
[0023] It is preferable that the single-yarn fineness of each fiber
forming the fiber bundled body (single yarn, monofilament) is 0.5
to 100 dtex. When the single-yarn fineness is too low, it is
difficult to align single yarns. Then, when the alignment of single
yarns is insufficient, it tends to happen that the mechanical
performance of the fiber cannot be sufficiently utilized. In
addition, when the single-yarn fineness is low, the attachment of a
bundling agent tends to be non-uniform, and predetermined cohesion
may not be obtained. When the number of single yarns is too large,
the cohesion tends to decrease. Meanwhile, in the case where the
single-yarn fineness is too large, the adhesion area between single
yarns is reduced. As a result, it becomes difficult to maintain the
bundled state of single yarns with a bundling agent, and the
reinforcing effect tends to decrease. It is more preferable that
the single-yarn fineness of each single yarn forming the bundled
body is 0.6 to 80 dtex. Further, the upper limit is 50 dtex or
less, particularly preferably 6.0 dtex or less. In addition, it is
preferable that the lower limit is 1.5 dtex or more, particularly
preferably 1.5 to 3.0 dtex.
[0024] The fiber bundled body used in the invention is a collection
of single yarns as described above, and preferably includes 50 to
3,000 single fibers. It is still more preferable that the fiber
bundled body includes 100 to 1,500 single fibers. It is more
preferable that the number of single fibers is 250 to 1100,
particularly preferably within a range of 500 to 1,100.
[0025] In the invention, usually, such a multifilament-type fiber
bundle is used. In some cases, it is also possible that a
monofilament-type fiber having a large fiber diameter is used as a
fiber bundled body. However, in the case of a monofilament-type
fiber, which is once wound up as a single monofilament after
spinning, with an increase in the fiber diameter, it becomes more
difficult to produce a high-strength fiber. In the invention, also
in terms of the reinforcing effect, it is preferable to use an
ordinary multifilament-type fiber bundled body.
[0026] In addition, it is preferable that the fiber bundled body
used in the invention is non-twisted or has a twist coefficient of
less than 3 (within a range of 0 to 3). Such twisting further
improves the reinforcing effect. In the case where the twist
coefficient is too large, the strength tends to decrease. This is
because as a result of twisting, at the time of pulling, a higher
force perpendicular to the direction of the fiber axis is caused by
single yarns. This phenomenon is particularly prominent in fibers
having poor flexibility. In addition, when the twist coefficient is
too large, the impregnation with a bundling agent tends to be
non-uniform, and the elongation tends to increase due to twist
shrinkage. When the twist coefficient is too small, the cohesion
tends to decrease. As a result, the reinforcing effect on cement
mortar or concrete tends to decrease. In the invention, it is more
preferable that the twist coefficient is preferably less than 2
(within a range of 0 to 2). Further, it is preferable that the
twist coefficient is within a range of 1.0 to 2.0, and it is
particularly preferable that the twist coefficient is 1.5 to 2.0.
As a result of twisting in such a preferred manner, when further
bundling is performed with a bundling agent, the integration as a
reinforcing material is enhanced. As a result, when the fiber
bundled body is kneaded in cement mortar or concrete, the cohesion
thereof is maintained, making it easy to ensure fluidity and
constructability in the material. Incidentally, here, with respect
to the twisting direction of the fiber bundled body, the bundled
body may be single-twisted as usual, or may also be plied, of
course.
[0027] Incidentally, here, the twist coefficient in the invention
is expressed as the product of the number of twists per unit length
and the square root of the fiber fineness, and is a value defined
by the following equation described in ASTM D 885: twist
coefficient={the number of twists (twists/m).times. fiber fineness
(dtex)}/1055.
[0028] In addition, it is preferable that the fiber used in the
invention has high strength. More specifically, it is preferable
that the fiber has a tensile strength of 7 cN/dtex or more. It is
still more preferable that the tensile strength is within a range
of 10 to 40 cN/dtex, particularly 20 to 40 cN/dtex. Here, in the
case where the tensile strength of the fiber is too low, when a
load is applied to cement mortar or concrete, the bending strength
of the formed product tends to be low, or, due to fiber breakage,
it tends to happen that the impact cannot be sufficiently
absorbed.
[0029] The fiber material for cement reinforcement of the invention
is configured such that a resin A containing an isocyanate compound
as a constituent component is present inside the fiber bundled body
described above, and a resin B containing an epoxy resin as a
constituent component is present on a surface of the fiber bundled
body. Further, it is preferable that the resin A contains a polyol
or an epoxy compound as a constituent component in addition to the
isocyanate compound.
[0030] Here, the resin A present inside the fiber bundled body
serves as a bundling agent for fibers. In the invention, it is
necessary that the resin A is a component containing an isocyanate
compound as a constituent component. In the invention, when such a
resin A is used, the resin A penetrates inside the fiber bundle and
also adheres single yarns together in the fiber bundle, thereby
facilitating firm bundling. Then, it is preferable that the resin A
is a resin having high toughness. More specifically, it is
preferable that the resin A is an isocyanate resin, a polyurethane
resin, a urea resin, a crosslinked isocyanate-epoxy, or the like.
In particular, an isocyanate resin, a urea resin, and a crosslinked
isocyanate-epoxy are preferable.
[0031] Then, in the invention, the method for bundling fibers with
the resin A is not particularly limited, and a method in which a
fiber bundle is immersed in a solution of the resin A dissolved in
an organic solvent such as toluene, followed by a heat treatment,
thereby giving a fiber bundled body utilizing the self-crosslinking
of the resin A, etc., a method in which a fiber bundle is immersed
in an aqueous dispersion of the resin A, followed by a heat
treatment, thereby giving a fiber bundled body utilizing the
self-crosslinking of the resin A, etc., and the like can be
mentioned. In terms of workability, it is preferable to use a
water-based agent.
[0032] More specifically, in the case where an isocyanate resin is
used as the resin A, a method in which a fiber bundle is immersed
in a solution of an isocyanate compound dissolved in an organic
solvent such as toluene, followed by a heat treatment, thereby
giving a fiber bundled body utilizing the self-crosslinking of the
isocyanate compound, a method in which a fiber bundle is immersed
in an aqueous dispersion of a waterborne blocked isocyanate,
followed by a heat treatment, thereby giving a fiber bundled body
utilizing the self-crosslinking of the isocyanate compound from
which the blocking agent has been dissociated, and the like can be
mentioned. In terms of workability, it is preferable to use a
water-based agent, and it is preferable that the isocyanate
compound in the resin A used in the invention is a blocked
isocyanate compound. In the case where such a waterborne blocked
isocyanate is used, the isocyanate does not react with water until
the step of evaporating moisture. Accordingly, the deactivation of
functional groups in steps before that, such as the immersion step,
can be suppressed.
[0033] It is preferable that the isocyanate compound is selected
from aromatic compounds, such as diphenylmethane diisocyanate and
toluene diisocyanate, and aliphatic compounds, such as
hexamethylene diisocyanate. Still more preferably, it is
recommended to use an aliphatic isocyanate having excellent
penetration into a fiber bundle. Further, it is preferable that
such a compound has a dimer structure or a trimer structure. In
addition, it is also preferable that the compound has a highly
reactive, tri- or higher functional isocyanate group. Specifically,
compounds having a hexamethylene diisocyanate (HDI) trimer
structure, for example, are preferable. A trimer structure is a
compound having, as its basic structure, acyclic structure formed
of three NCO groups at the HDI terminal.
[0034] Then, in the case where the isocyanate compound is a blocked
isocyanate compound, with respect to compounds for blocking
isocyanate groups, specifically, dimethylpyrazole-blocked,
methyl-ethyl-ketone-oxime blocked, caprolactam-blocked, and like
blocked isocyanates are preferable. Among them, it is preferable to
use a dimethylpyrazole-blocked isocyanate compound, particularly
dimethylpyrazole-blocked hexamethylene diisocyanate. In particular,
a dimethylpyrazole-blocked compound is a heterocyclic compound
containing a nitrogen atom and the like in the cyclic structure in
addition to a carbon atom, and is likely to have a resonance
structure. Accordingly, the blocked compound is unblocked at lower
temperatures, and thus such a compound is more preferably used. In
particular, in terms of reactivity and unblocking temperature, it
is preferable to use a compound blocked with dimethylpyrazole or
the like and having an aliphatic tri- or higher functional
isocyanate group (dimethylpyrazole block-HDI trimmer, etc.).
[0035] Such a dimethylpyrazole-blocked isocyanate compound has high
compatibility with the fiber-forming polymer. Then, when the fiber
having attached thereto such a compound is heat-treated, and,
according to the thermal history, the compound is allowed to
thermally diffuse into the fibers over a sufficient period of time,
resulting in high interface-reinforcing ability.
[0036] In addition, it is also preferable to use a polyurethane
resin as the resin A. A polyurethane resin is a resin obtained by
the condensation of a polyol and an isocyanate compound. Then, as a
method for using such a resin, it is possible to employ a method in
which a fiber bundle is immersed in a solution of a polyol and an
isocyanate dissolved in an organic solvent or a solution containing
an aqueous dispersion of a waterborne polyol and a waterborne
blocked isocyanate, followed by a heat treatment, thereby giving a
fiber bundled body; a method in which fibers are immersed in a
solution of a pre-condensed urethane resin dissolved in an organic
solvent or in an aqueous dispersion thereof, and then the organic
solvent or water is dried, thereby giving a fiber bundled body; or
the like. In addition, it is also preferable to use a urea resin as
the resin A. Here, a urea resin is a resin obtained by the
condensation of an amine and an isocyanate compound.
[0037] Among them, it is particularly preferable that the resin A
is a crosslinked isocyanate compound-epoxy compound. As a method
for using such a resin, an isocyanate compound having a relatively
low molecular weight and a highly reactive epoxy compound similarly
having a relatively low molecular weight are penetrated into
fibers, followed by a heat treatment, whereby a preferred fiber
bundled body can be obtained. When the compounds are crosslinked
from the inside of a fiber bundle in this manner, single yarns are
firmly adhered together inside the fiber bundle, and a firmly
bundled fiber bundled body can be obtained. In particular, it is
particularly preferable to use an aqueous dispersion of a blocked
isocyanate having an aliphatic hexamethylene diisocyanate (HDI)
structure, which has excellent penetration into a fiber bundle, and
a water-soluble high epoxy compound having a sorbitol polyglycidyl
ether structure. More specifically, it is preferable that
dimethylpyrazole-blocked hexamethylene diisocyanate or
caprolactam-blocked diphenylmethane diisocyanate is used as a
blocked isocyanate, and a sorbitol polyglycidyl ether-type epoxy
compound is used in combination as an epoxy compound.
[0038] In addition, in the invention, more specifically, specific
methods for attaching the resin A used as a bundling agent to the
inside of a fiber bundled body are as follows. A multifilament
(long fiber) formed of a collection of single fibers, a plurality
of such fibers aligned, or long fibers in tow form are continuously
fed from a bobbin or a beam creel. Then, (1) the fibers are
impregnated in a tank containing the bundling agent, (2) the
bundling agent is attached by a roller touch method, or (3) the
bundling agent is sprayed and attached, for example. Among them, in
order to uniformly attach the resin A to fibers, the method (1) in
which the fibers are impregnated in a tank containing the bundling
agent is preferable, and it is still more preferable that the
amount attached is subsequently adjusted to a certain amount with a
squeeze roller.
[0039] In addition, in order to promote the impregnation and
penetration of the resin A to serve as a bundling agent into the
fiber bundle as described above, a method in which the bundling
agent is dispersed or dissolved in a water-based emulsion or an
organic solvent, thus diluted, and used is preferable. In
particular, as a method for implementing the invention, it is
preferable to perform a water-based treatment. An organic solvent
having dissolved therein a bundling agent has increased viscosity,
and its penetration into a fiber bundle tends to be insufficient.
Also from this point of view, in the invention, it is preferable to
use a compound having a relatively low molecular weight, which has
increased water solubility. In addition, in the case where a
treatment method in which the bundling agent is dissolved in an
organic solvent is employed, it is necessary to use a large amount
of organic solvent. In terms of safety and work environment load,
and also in terms of cost for the adhesion treatment facility, the
treatment of recovered/waste liquid, and the peripheral facilities,
a water-based treatment is preferable.
[0040] Usually, it is preferable that the fiber bundle having
applied thereto a bundling agent is then subjected to a heat
treatment to dry the dispersion medium for the bundling agent, or
occasionally cause crosslinking by the heat treatment. As a
treatment device, a contact hot roller and the like are usable.
However, it is preferable to use a non-contact hot-air drying
furnace, which prevents the bundling agent from adhering to or
soiling the device and thus facilitates the work. The treatment
temperature at this time is about 105 to 300.degree. C., and it is
particularly preferable that drying is performed at about 120 to
250.degree. C. According to one preferred embodiment, in this stage
or after the following treatment with the resin B, the obtained
fibrous material is cut to a predetermined fiber length with a
known cutting machine.
[0041] With respect to the amount of the resin A attached, it is
preferable that the resin A is applied in an amount of 3 to 15 wt %
relative to the total fiber weight. In the case where the amount
attached is too small, it tends to happen that the bundle is
released, and the single fibers come apart, resulting in loss of
the fluidity of the material. This is because when a shear force is
applied to fibers during kneading with concrete or mortar, the
bundling of fibers with a bundling agent cannot be maintained.
Meanwhile, in the case where the amount attached is too large, the
strength of fibers tends not to be sufficiently utilized. In the
case where the amount attached is increased too much, the cohesion
itself is not much improved. In addition, another reason is that
when the amount of the resin attached is large, due to an increase
in the apparent fineness of the fiber bundled body, the tensile
strength of the bundled fiber per weight also decreases. In the
invention, the amount of the resin A attached relative to the fiber
weight is more preferably 5.0 to 15.0 wt %, and particularly
preferably within a range of 7.0 to 10.0 wt %.
[0042] The fiber material for cement reinforcement of the invention
is configured such that the resin A containing an isocyanate
compound as a constituent component is present inside a fiber
bundled body as described above, and it is further necessary that a
resin B containing an epoxy resin as a constituent component is
present on a surface of the fiber bundled body. Here, when the
fiber bundle is composed only of the resin A, the interfacial
adhesion force with concrete or mortar is not sufficient, and it is
necessary in the invention that the surface thereof is coated with
the resin component B. The isocyanate compound used as the resin A,
which has excellent affinity for water, has a relatively low
molecular weight, and even at the time of crosslinking, the
functional group reacts with water and is deactivated, causing no
increase in the molecular weight. As a result, the cohesive
strength tends to be insufficient. In addition, as a result of
penetrating into the inside of the fiber bundle, the amount of the
resin A attached to the fiber bundle surface tends to be small, and
the fiber bundle surface becomes flat, resulting in insufficient
interfacial adhesion. However, it is believed that because of the
presence of the resin B containing an epoxy resin as a constituent
component, the interfacial adhesion strength with cement is
increased.
[0043] Here, the resin B containing an epoxy resin as a constituent
component should be a resin obtained by the reaction of a compound
having an epoxy group as one of the constituent components. More
specifically, as the resin B, as long as it is a resin obtained by
the reaction of a compound having an epoxy group as one of the
constituent components, any of those available as adhesives or
coating materials in the open market may be used. However, a resin
whose main component is a resin obtained by the reaction of a
compound having an epoxy group as one of the constituent components
is preferable. Further, in terms of cohesive strength and
interfacial adhesion strength, an acrylic-modified epoxy resin and
a bisphenol-A epoxy resin, which exhibit high performance, are
preferable. It is particularly preferable that the resin B is a
resin composed of an acrylic-modified bisphenol-A epoxy resin.
[0044] Further, it is also preferable that such an acrylic-modified
epoxy resin is a resin having a high degree of acrylic
modification, which is called an epoxy acrylate resin or a vinyl
ester resin. This epoxy acrylate resin is a synthetic resin
obtained by adding an acrylic group or a methacrylic group to an
epoxy resin prepolymer, and is a resin resulting from the reaction
between an epoxy resin and a (meth)acrylic acid. Further, it is
preferable that the resin has the same bisphenol skeleton as a
bisphenol-A epoxy resin on the main chain and has an unsaturated
ester group (vinyl ester group) on the side chain.
[0045] In addition, it is preferable that the molecular weight of
the resin B is 10,000 or more. Also in terms of the convenience of
the processing treatment, it is preferable that the treatment
liquid containing the resin B is a water-based emulsion.
[0046] In addition, although the resin B of the invention is used
as a coating agent, for the purpose of improving strength and
toughness or imparting heat resistance and chemical resistance, it
is also preferable to add a known hardener, such as a melamine
resin, a phenol resin, or a blocked isocyanate. The proportion of
the hardener blended is not particularly limited, but it is
preferable that the bisphenol-A or like epoxy resin, which is a
base compound, is 50 wt % or more on a solid basis.
[0047] With respect to the amount of the resin B attached, it is
preferable that the resin B is applied in an amount of 0.1 to 10 wt
% relative to the total fiber weight. In the case where the amount
attached is too small, when a stress is applied inside concrete or
cement, the cohesive strength at the interface may be insufficient.
Thus, it tends to happen that the fiber reinforcing material is
easily shed and does not exhibit sufficient reinforcing properties.
Meanwhile, in the case where the amount attached is too large, the
amount of the coating agent in the reinforcing material increases.
Accordingly, due to an increase in the apparent fineness, the
tensile strength of the fiber reinforcing material decreases, and
the strength of the fiber tends not to be sufficiently utilized. It
is more preferable that the resin B is attached in an amount of 0.5
to 5.0 wt %, still more preferably within a range of 1.0 to 3.0 wt
%. Further, it is particularly preferable that the total amount of
the resins A and B attached to the fiber bundle is 8.0 to 15 wt
%.
[0048] In addition, as a combination of the resin A and the resin
B, it is preferable that the isocyanate compound contained in the
resin A is a blocked isocyanate, while the resin B contains an
acrylic-modified epoxy resin as a main component, or that the
isocyanate compound contained in the resin A is a blocked
isocyanate, and the resin B contains a bisphenol-A epoxy resin as a
main component. In particular, it is preferable that the resin B
contains an acrylic-modified bisphenol-A epoxy resin as a main
component.
[0049] Because of the synergistic effects of the resin A inside the
fiber bundle and the resin B on the fiber bundle surface as
described above, the fiber material for cement reinforcement of the
invention has become a fiber bundle having sufficient cohesion. The
fiber material of the invention is suitable for use in cement
mortar or concrete as described below. However, in the case where a
high shear force is applied to the fibers at the time of kneading
during the production process, and the bundle is released, the
reinforcing effect of the fibers decreases. Further, unbundled
single fibers are likely to be entangled with each other and form
large fiber agglomerates, resulting in a decrease in the fresh
fluidity or constructability of cement mortar or concrete. However,
because of its high cohesion, the fiber material for cement
reinforcement of the invention has an excellent reinforcing effect
and excellent constructability. Particularly in recent years,
high-strength or ultrahigh-strength mortar and concrete have been
required. They generally have a low water/binder ratio, resulting
in a high-viscosity material, whereby an even higher shear force is
applied to the fiber material for reinforcement. For this reason,
the fiber material of the invention with high cohesion is
particularly useful.
[0050] The fiber material for cement reinforcement of the invention
is configured such that the resin A containing an isocyanate
compound as a constituent component is present inside a fiber
bundled body as described above, and the resin B containing an
epoxy resin as a constituent component is present on a surface of
the fiber bundled body. Then, the diameter of the bundled fiber
reinforcing material and the fiber length of the fiber bundled body
affect the bending toughness of a concrete or mortar formed body.
That is, the presence of the fiber reinforcing material increases
the bending fracture energy (sometimes referred to as "bending
energy") of a concrete or mortar formed body.
[0051] It is preferable that the diameter of the bundled fiber
reinforcing material is 0.05 to 1.0 mm, more preferably 0.1 mm to
0.8 mm, and still more preferably 0.3 mm to 0.5 mm. It is
preferable that the length is 1 to 50 mm, more preferably 5 mm to
40 mm, and particularly preferably within a range of 15 mm to 35
mm. The impact on bending energy and fresh fluidity may also be
considered from the aspect ratio expressed as the relation of the
fiber length [mm]/the diameter of the fiber bundled body [mm]. It
is preferable that the aspect ratio is 30 to 120, more preferably
50 to 80. When the size is as above, the reinforcing effect of
fiber incorporation, that is, suppressed cracking, increased
bending strength/increased bending toughness (increased bending
fracture energy), or the like, can be imparted more
effectively.
[0052] When the diameter of the bundled fiber reinforcing material
is reduced, or the fiber length is increased, that is, when the
aspect ratio is increased, the total contact surface area of the
fibers with cement mortar or concrete increases, making it possible
to increase the attachment strength. Further, it becomes possible
to significantly improve the bending energy. However, meanwhile,
when the aspect ratio is too high, an increased number of fibers
break. As a result, when the width of cracks increases, the
reinforcing effect decreases, and the bending energy tends to
decrease. In addition, at the time of kneading in cement mortar or
concrete, a high shear force is applied to the fibers, making it
difficult to maintain the cohesion with the bundling agent.
Further, in some cases, the bundle is released into single fibers,
impairing the fluidity of the material.
[0053] Conversely, when the diameter of the bundled fiber
reinforcing material is increased, or the fiber length is reduced,
that is, when the aspect ratio is reduced, the cutting of fibers is
unlikely to occur, and the energy at the time of the shedding of
fibers can be utilized at maximum. However, meanwhile, when the
fiber length of the bundled fiber is too short, or the diameter is
too large, that is, when the aspect ratio is too low, the total
contact surface area of the fibers with cement mortar or concrete
is small, and it tends to be impossible to obtain a sufficient
reinforcing effect.
[0054] Considering the dispersibility of the fiber material for
reinforcement, short fibers having a small fiber length are
preferable, while in terms of improving the reinforcing effect, it
is preferable to use short fibers having a large fiber length.
However, with respect to the fiber length, it is necessary to
consider the deterioration of the workability due to a decrease in
dispersibility or the generation of fiber agglomerates due to the
entanglement of fibers during stirring, and it is preferable that
the fiber length is within the above range.
[0055] By using such a fiber material for cement reinforcement of
the invention, it has been made possible to improve the bending
energy of the finally obtained concrete or mortar formed body. That
is, after the initial cracking of a concrete or mortar formed body,
the fiber bundled body bridges the crack, whereby the formed body
is reinforced. However, although some fibers contribute to the
reinforcement until breakage, other fibers are shed. However, the
frictional force between the fiber bundled body and the concrete or
mortar formed body at the time of shedding also significantly
contributes to the bending energy. For example, looking at a
stress-strain curve in a bending test after initial cracking, it is
preferable that the diameter, the fiber length, and the like of the
fiber bundled body are varied depending on the application, such as
the case where the reinforcing effect within a narrow range where
the crack width is less than 2 mm, etc., is expected, or the case
where the reinforcing effect within a wide range, where the crack
width is up to 6 mm, etc., is expected. Although this is affected
by the attachment strength between each fiber bundled body and the
concrete or mortar formed body, especially in a region having a
small crack width, long fibers having a large aspect ratio, which
have excellent adhesion strength, are effective.
[0056] In addition, it is preferable that the concrete fiber
material for reinforcement of the invention has high strength. More
specifically, it is preferable that the tensile strength of the
fiber bundled body forming the fiber material is 7 cN/dtex or more,
particularly preferably within a range of 10 to 40 cN/dtex. Here,
the strength of the fiber material for reinforcement is measured
after treatments with the resin A and the resin B and before
cutting in the length direction. Here, in the case where the
tensile strength of the fiber material is too low, when a load is
applied to cement mortar or concrete, the bending strength of the
formed product tends to be low, or the impact strength tends to
decrease.
[0057] In addition, the incorporation rate of fibers forming the
fiber material for reinforcement of the invention into cement
mortar or concrete may be selected according to the purpose.
However, it is usually preferable that the fibers are used within a
range of 0.01 to 10.0 vol %, more preferably within a range of 0.05
to 5.0 vol %, still more preferably 0.1 to 3.0 vol %, and
particularly preferably within a range of 0.2 to 1.5 vol %.
Further, in another preferred mode, the fiber material for
reinforcement of the invention and an existing fiber material are
used in combination. In the case where the fiber incorporation rate
is too low, the suppression of cracking and the impartment of
strength and toughness tend to decrease. Conversely, when the fiber
incorporation rate is too high, fibers are entangled with each
other, resulting in the formation of fiber agglomerates or
defective dispersion of fibers. Then, the fluidity of cement mortar
or concrete when fresh is impaired, and the workability at the time
of construction tends to be inhibited. Further, in the case where
the incorporation rate is too high, it becomes difficult to obtain
a reinforcing effect or a toughness-improving effect that matches
the fiber incorporation rate. In addition, the compressive strength
of the cement mortar or concrete also decreases. However, as long
as the incorporation rate is within an ordinary range, whether the
amount of fiber incorporation is large or small does not have
significant impact on compressive strength.
[0058] Here, the fiber incorporation rate (Vf: fiber volume
fraction) is a proportion (vol %) expressed by the following
equation: Vf=(V.sub.1/V.sub.2).times.100.
[0059] (In the equation, V.sub.1 represents the volume (liter) of
the fibers for reinforcement incorporated per unit volume (1,000
l=1 m.sup.3) of the fiber-containing cement formed body, and
V.sub.2 represents the unit volume (1,000 l=1 m.sup.3) of the
cement formed body).
[0060] The fiber material for reinforcement of the invention is
particularly effective for cement serving as a binder for concrete
or mortar, and is preferably used for concrete reinforcement and
mortar reinforcement. Cement serving as a binder for concrete or
mortar is selected considering the construction conditions of the
worksite and the like, and the fiber material for cement
reinforcement of the invention can be combined with various types
of cement. More specifically, for example, various types of
Portland cement such as ordinary cement, high-early-strength
cement, ultrahigh-early-strength cement, low-heat cement, and
moderate-heat cement, as well as various types of blended cement
such as Portland blast furnace cement prepared by mixing these
various types of Portland cement with fly ash, blast furnace slag,
or the like, rapid hardening cement, and the like, can be
mentioned. They can be used alone or as a mixture of two or more
kinds.
[0061] Now, the fiber material for cement reinforcement of the
invention is preferably used as a material for concrete or mortar
together with the above cement (binder), and provides a concrete or
mortar formed body containing the fiber material for cement
reinforcement, which is another embodiment of the invention.
[0062] At this time, together with the fiber material for
reinforcement of the invention, it is preferable that known
admixtures (binders) are added to the cement to be reinforced.
Examples of admixtures include blast furnace slag powder, fly ash,
silica fume, limestone powder, quartz powder, gypsum dihydrate,
gypsum hemihydrate, gypsum anhydrite, quicklime-based expansive
admixtures, and calcium sulfoaluminate-based expansive admixtures.
Their proportions are not particularly limited, and various designs
are possible.
[0063] Further, it is preferable that the following aggregates are
added to the fiber material for cement reinforcement of the
invention to form a concrete or mortar formed body containing
aggregates. Such aggregates for concrete or mortar may only be fine
aggregates, such as river sand, beach sand, mountain sand, crushed
sand, silica sands Nos. 3 to 8, limestone, and slag fine
aggregates. Alternatively, according to the required properties of
the application, it is also preferable that coarse aggregates, such
as river gravel, crushed stone, and artificial aggregates, are
mixed with fine aggregates and used. With respect to the
aggregate/cement (binder) ratio in concrete or mortar, in terms of
suppressing hydration heat, suppressing dry shrinkage, and reducing
the cost, it is preferable that the aggregates are 50% or more.
[0064] In addition, generally, in the case where the proportion of
coarse aggregates in the aggregates is large, processing is
difficult. However, in the case where the fiber material for cement
reinforcement of the invention is used together, the interfacial
adhesion effect with a binder (cement) is improved. As a result,
even when the proportion of coarse aggregates is large, effective
strength and processability can be maintained.
[0065] That is, the fiber material for cement reinforcement of the
invention causes a sufficient reinforcing effect even at a low
fiber incorporation rate. Accordingly, the fiber material is
particularly effective for concrete or mortar that has a low
water/binder ratio, has a high coarse aggregate content, or has
high material viscosity and is difficult to process. More
specifically, it is preferable that the fiber material is used for
a concrete or mortar formed body having a water/binder ratio of 45%
or less, still more preferably 40% or less. Further, the fiber
material is optimal for use in mortar or concrete having a
water/binder ratio of 25% or less, or in mortar or concrete having
a water/binder ratio of 45% or less and an aggregate/binder ratio
of 250% or more.
[0066] In particular, the fiber material for cement reinforcement
of the invention can be preferably used in the case where the
water/binder ratio is 25% or less, particularly preferably in the
case of a water/binder ratio of 10 to 20%. The mechanical
properties of the concrete or mortar obtained using cement having
such a low water/binder ratio can be further enhanced. The fiber
material of the invention may also be used with the water/binder
ratio being normally high. However, when the water/binder ratio is
too low, sufficient kneading is difficult even with the fiber
material of the invention.
[0067] In steps before such a fiber material for cement
reinforcement of the invention forms a concrete or mortar formed
body, a suitable amount of kneading water is added to cement and
the like and kneaded. Then, it is preferable to employ a method for
producing a concrete or mortar formed body containing the fiber
material for cement reinforcement of the invention and having a
water/binder ratio of 45% or less at the time of kneading. As the
kneading water at this time, as long as components that adversely
affect the hardening of cement and the like are not contained, tap
water, underground water, river water, and like water can be used.
However, it is preferable to use water conforming to "JIS A 5308,
Appendix 9, Water Used for Kneading of Ready-Mixed Concrete."
[0068] Then, in order to obtain mortar (cement mortar), sand (fine
particulate aggregates, fine aggregates), cement, and water are
kneaded to paste-like softness, and the fiber material for cement
reinforcement of the invention is mixed therewith. In the case of
concrete, in addition to the fine particulate aggregates, larger
coarse aggregates (gravel, etc.) are mixed.
[0069] At this time, in the concrete or mortar formed body, without
substantially interfering with the object, it is also possible to
use additives in addition to the above materials. Examples of
additives include AE water reducing agents, high-range AE water
reducing agents, shrinkage reducing agents, setting retarders,
hardening accelerators, thickeners, defoaming agents, foaming
agents, anti-corrosive agents, anti-freezing agents, clay
mineral-based thixotropy-imparting agents, colorants, and water
retention agents.
[0070] Then, the use of the fiber material for cement reinforcement
of the invention has made it possible to obtain concrete or mortar
having excellent physical properties. Specific examples of methods
for adding the fiber material to concrete or mortar include a
method in which cement, fine aggregates, coarse aggregates, and the
like are previously mixed with the fiber material for cement
reinforcement of the invention to form a dry premix, and then
kneading water is added and kneaded, and also a method in which
cement, fine aggregates, and coarse aggregates, and the like are
sufficiently stirred with kneading water, and then the reinforcing
material of the invention is finally added and kneaded.
[0071] As a kneading machine used for stirring the cement mortar or
concrete containing the fiber material for reinforcement of the
invention, it is possible to use a pan-type mixer, a tilting mixer,
an Omni mixer, a Hobart mixer, a truck mixer, or the like.
[0072] Even during the kneading step, the cohesion of fibers in the
fiber material for cement reinforcement of the invention is high.
Thus, even during kneading that causes a high shearing force, such
as the kneading of concrete or mortar having a low water/binder
ratio, breakage hardly occurred, and the fluidity and
constructability of the material were not inhibited. Further, in
the concrete or mortar formed product reinforced with the fiber
material for cement reinforcement of the invention, fibers do not
undergo rapid breakage even when the applied stress increases. As a
result, the bending fracture energy of the formed product was
significantly improved.
[0073] The applications of such concrete or mortar formed bodies
containing the fiber material for cement reinforcement of the
invention are not particularly limited, and they can be widely used
for general civil engineering and architectural applications. For
example, by employing spray molding, press molding, vibration
molding, centrifugation molding, and the like, wide variety of
applications are possible, including the reinforcement of slopes,
the foundation work of building structures, and the like. Further,
also with respect to the production of secondary formed products
(blocks, plate-like products, sheet-like products, tetrapods,
etc.), various forming methods may be employed. In addition, in the
case of mortar, in addition to use for the rough coating or finish
coating of a concrete surface, it is also preferable to use the
mortar for joints of bricks and concrete blocks, for example.
EXAMPLES
[0074] Hereinafter, the invention will be described in further
detail with reference to examples and comparative examples.
Incidentally, for each evaluation in the examples, measurement was
performed as follows.
(1) Fiber Length, Fineness
[0075] Measurement was performed in accordance with JIS-L-1015.
(2) Fiber Tensile Strength
[0076] Measurement was performed in accordance with ASTM D 885.
(3) Fiber Bundle Diameter and Fiber Bundle Length of Bundled Fiber
Bundle
[0077] With respect to a treated fiber bundle (treated yarn), which
had been treated with a bundling agent and cut, the diameter of the
fiber bundle and the length of the fiber bundle were measured with
a digital vernier caliper (manufactured by A&D Company,
Limited).
(4) Bundling Properties of Bundled Fiber Bundle
[0078] A cross-section of a fiber bundle, which had been treated
with a bundling agent, was observed under a scanning electron
microscope to see whether single yarns were adhered together inside
the fiber bundle, and evaluation was performed as follows.
[0079] Excellent: Adjacent single yarns, including single yarns
located in the central part of the fiber bundle, are adhered
together.
[0080] Fair: Adjacent single yarns, including single yarns located
in the inner part (about 1/4 to 3/4 of the radius) of the fiber
bundle, are adhered together.
[0081] Poor: Most of the resin is attached to the outer peripheral
part of the fiber bundle, and only single yarns in the surface
layer of the fiber bundle are adhered to adjacent single yarns.
(5) Bundling Properties of Fiber Bundle after Kneading
[0082] The obtained fiber reinforcing material was stirred with
cement, aggregates, water, and the like by the method described in
the following reference example, thereby giving ready-mixed
concrete (or unhardened cement mortar).
[0083] Next, a small amount of the obtained ready-mixed concrete
(or unhardened cement mortar) was scooped up, washed with water,
and the extracted fibers for reinforcement were visually observed.
At this time, when the fiber material was coated with the bundling
agent, and the single yarns were not separated, the cohesion was
judged to be excellent. Meanwhile, when the fiber bundle came
apart, and cement was attached between single yarns in 10% or more
of the entire fiber material, the cohesion was judged to be
poor.
(6) Fluidity of Ready-Mixed Concrete
[0084] Using the ready-mixed concrete (or unhardened cement mortar)
described in the reference example, the following step was
performed after the kneading step. Above a 50-cm square,
horizontally disposed aluminum board, the ready-mixed concrete was
poured into a slump cone (conical post having a height of 15 cm, a
bottom inner diameter of 10 cm, and a top inner diameter of 5 cm,
with a hollow interior) while scraping off the excess, and the
slump cone was slowly vertically pulled up. At this time, the
ready-mixed concrete spreads in a circle over the aluminum board.
The diameter of the spread circle at this time, or alternatively
the arithmetic average of the shortest diameter and the longest
diameter in the case of a distorted circle, was measured as a flow
value. The flow value reflects the fluidity of the ready-mixed
concrete. When the flow value was 250 mm or more, the concrete was
judged to have "excellent constructability", while when it was less
than 200 mm, the concrete was judged to have "poor
constructability." [0077]
(7) Compressive Strength and Bending Fracture Energy of Concrete
Formed Product
[0085] The ready-mixed concrete (or unhardened cement mortar)
obtained in the reference example was used.
[0086] First, in accordance with JIS A 1132, a cylinder having a
diameter of 100 mm was produced and then cured at 20.degree. C. and
90% RH until a material age of 28 days, thereby giving a
cylindrical test piece. Subsequently, measurement was performed in
accordance with JIS A 1108 to determine the compressive
strength.
[0087] In addition, the ready-mixed concrete obtained in the
reference example was placed in a mold 40 mm wide.times.40 mm
high.times.160 mm long, and cured at 20.degree. C. and 90% RH until
a material age of 28 days, thereby giving a test piece for the
measurement of bending fracture energy.
[0088] The above test piece was subjected to a three-point bending
test in accordance with JIS R 5201. More specifically, using a 10-t
tensile compression tester (manufactured by Toyo Baldwin
Corporation, "UNIVERSAL TESTING INSTRUMENT MODEL UTM 10 t"), the
center of a 10-cm distance between support points was compressed at
a rate of 2 mm/min. Then, from the measurement data of bending
stress-strain obtained, the fracture energy necessary for the
fracture of the test piece until a crack mouth opening displacement
of 6 mm was calculated. A fracture energy of 10 kN/mm.sup.2 or more
was judged to be excellent, and a fracture energy of 10 kN/mm.sup.2
or less was judged to be poor.
Reference Example 1
(Preparation of Ready-Mixed Concrete)
[0089] Using a mortar mixer (manufactured by Marui & Co., Ltd.,
"MIC-362", volume: 5 L), each of the fiber reinforcing materials
obtained in the examples and comparative examples was kneaded at a
stirring rate of 140 rpm for about 3 minutes together with 1,000 g
of low-heat Portland cement (manufactured by Taiheiyo Cement
Corporation), 200 g of silica fume (manufactured by Elkem AS), 500
g of fine aggregates (manufactured by San-Ei Silica Co., Ltd.,
"Silica Sand No. 6"), 400 g of coarse aggregates (manufactured by
Kansai Matec Co., Ltd., "Crushed Stone 1505"), 30 g of a high-range
water reducing agent ("Rheobuild SP8HU" manufactured by BASF), and
200 g of water.
[0090] As a result, ready-mixed concrete having a water/binder
ratio of 19.2% and an aggregate/binder ratio of 75.0% was
obtained.
Reference Example 2
(Preparation of Uncured Cement Mortar)
[0091] Using a mortar mixer (manufactured by Marui & Co., Ltd.,
"MIC-362", volume: 5 L), each of the fiber reinforcing materials
obtained in the examples and comparative examples was kneaded at a
stirring rate of 140 rpm for about 3 minutes together with 450 g of
low-heat Portland cement (manufactured by Taiheiyo Cement
Corporation), 1,700 g of fine aggregates (manufactured by San-Ei
Silica Co., Ltd., "Silica Sand No. 6"), 10 g of a high-range water
reducing agent ("Rheobuild SP8HU" manufactured by BASF), and 170 g
of water.
[0092] As a result, unhardened cement mortar having a water/binder
ratio of 40.0% and an aggregate/binder ratio of 380% was
obtained.
Example 1
[0093] As a fiber to form a fiber material for reinforcement, a
copolymerized aramid fiber (copolymerized aromatic polyamide fiber,
"Technora" manufactured by Teijin Limited, 1,670 dtex, the number
of filaments: 1,000, tensile strength: 24.5 cN/dtex, "strength
retention under conditions of 120.degree. C., saturated water
vapor, 100 hours: 99%") was used. Using a twisting machine, the
fiber was single-twisted to give a fiber bundle having a twist
coefficient of 2.
[0094] As the resin A to serve as a bundling agent, a sorbitol
polyglycidyl ether-based epoxy compound (manufactured by Nagase
ChemteX Corporation, "EX614B") and dimethylpyrazole-blocked
hexamethylene diisocyanate (manufactured by Baxenden, "Trixene Aqua
201", dimethylpyrazole block-HDI trimmer) were mixed at a ratio of
50:50 wt % on a solid basis, thereby giving a resin-A-containing
liquid having a total solid content of 10 wt %.
[0095] The obtained fiber bundle was immersed in the
resin-A-containing liquid and then dried at a temperature of
200.degree. C., thereby giving a fiber bundle having attached
thereto a bundling agent at 10 wt %.
[0096] As the resin B to serve as a coating agent, an aqueous
dispersion having a solid content of 10 w % and containing a
carboxyl-group-containing acrylic-modified bisphenol-A epoxy resin
("DIC FINE EN" manufactured by DIC Corporation) was prepared.
[0097] Subsequently, the fiber bundle having attached thereto the
resin A was immersed in the aqueous dispersion of the resin B.
Subsequently, the fiber bundle was dried at a temperature of
200.degree. C., thereby giving a treated fiber bundle in which the
amount of the coating agent (resin B) attached to the treated fiber
bundle was 3 wt %. The diameter of the obtained treated fiber
bundle was 0.45 mm. The treated fiber bundle was cut to 30 mm to
give a fiber material for cement reinforcement. The physical
properties are shown in Table 1.
[0098] Using the fiber material for reinforcement, the ready-mixed
concrete having a water/binder ratio of 19.2 of Reference Example 1
was cured, thereby giving a concrete formed body (the incorporation
rate of the fiber material for reinforcement: 1 vol %). The
evaluation results are shown in Table 1 (incidentally, some of the
evaluation results are also shown in Table 2 for comparison).
[0099] Next, using the unhardened cement mortar having a
water/binder ratio of 40.0% of Reference Example 2 in place of the
ready-mixed concrete of Reference Example 1, a mortar formed body
having an incorporation rate of the fiber material for
reinforcement increased from 1 vol % to 3 vol % was obtained. The
evaluation results are shown in Table 2.
Example 2
[0100] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the resin component B to serve as a coating
agent was changed from the acrylic-modified product used in Example
1 to a bisphenol-A epoxy resin ("jER" manufactured by Mitsubishi
Chemical Corporation). The results are also shown in Table 1.
Example 3
[0101] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the resin component A to serve as a bundling
agent was changed from the dimethylpyrazole-blocked hexamethylene
diisocyanate used in Example 1 to a mixed solution of a sorbitol
polyglycidyl ether-based epoxy compound and caprolactam-blocked
diphenylmethane diisocyanate (GRILBOND IL-6 manufactured by EMS) as
the resin component A. The results are also shown in Table 1.
Example 4
[0102] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that as the resin component A to serve as a
bundling agent, the epoxy compound used in Example 1 was not used,
and dimethylpyrazole-blocked hexamethylene diisocyanate was used
alone. The results are also shown in Table 1.
Example 5
[0103] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that a urethane resin ("BONDIC HS770"
manufactured by DIC Corporation) was used as the resin component A
to serve as a bundling agent. The results are also shown in Table
1.
Example 6
[0104] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the fiber used was changed from the
copolymerized aramid fiber used in Example 1 to an aramid fiber
made of a homopolymer (aromatic polyamide fiber, "Twaron"
manufactured by Teijin Limited, 1,680 dtex, the number of
filaments: 1,000, tensile strength: 20.8 cN/dtex). The results are
also shown in Table 1.
Example 7
[0105] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the fiber used was changed from the
copolymerized aramid fiber of Example 1 to a carbon fiber ("TENAX"
manufactured by Toho Tenax Co., Ltd., 2,000 dtex, the number of
filaments: 3,000, tensile strength: 15.0 cN/dtex). The results are
also shown in Table 1.
Example 8
[0106] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the fiber used was changed from the
copolymerized aramid fiber having a total fineness of 1,670 dtex
used in Example 1 to a fiber having a total fineness of 440 dtex
(copolymerized aromatic polyamide fiber, "Technora" manufactured by
Teijin Limited, 440 dtex, the number of filaments: 267), and the
diameter of the treated reinforcing fiber material was 0.25 mm,
which is about half. The results are also shown in Table 1.
Example 9
[0107] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the fiber used was changed from the treated
reinforcing fiber material of Example 1 having a length of 30 mm to
one having a length to 15 mm. The results are also shown in Table
1.
Example 10
[0108] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the fiber used was changed from the treated
reinforcing fiber material of Example 1 having a length of 30 mm to
one having a length to 35 mm. The results are also shown in Table
1.
Example 11
[0109] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the incorporation rate of the fiber material
for cement reinforcement into a concrete formed body was changed
from 1 vol % of Example 1 to 0.5 vol %. The results are also shown
in Table 1.
Example 12
[0110] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the incorporation rate of the fiber material
for cement reinforcement into a concrete formed body was changed
from 1 vol % of Example 1 to 2.0 vol %. The results are also shown
in Table 1.
Comparative Example 1
[0111] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the resin A to serve as a bundling agent was
not used, and only the carboxyl-group-containing acrylic-modified
bisphenol-A epoxy resin used as the coating agent resin B in
Example 1 was used. The results are also shown in Table 1.
Comparative Example 2
[0112] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that the resin B to serve as a coating agent was
not used, and only the sorbitol polyglycidyl ether-based epoxy
compound and dimethylpyrazole-blocked hexamethylene diisocyanate,
which are components blended as the bundling agent resin A in
Example 1, were used. The results are also shown in Table 1.
Comparative Example 3
[0113] A fiber material for cement reinforcement and a concrete
formed body were produced and evaluated in the same manner as in
Example 1, except that in place of the resin A to serve as a
bundling agent in Example 1, a sorbitol polyglycidyl ether-based
epoxy compound was used alone without using a blocked isocyanate.
The results are also shown in Table 1.
Comparative Example 4
[0114] The fiber used was changed from the copolymerized aramid
fiber used in Example 1 to a PVA monofilament fiber (manufactured
by Kuraray Co., Ltd., "RF 4000", 4,000 dtex, the number of
filaments: 1, tensile strength: 6.9 cN/dtex). Then, a concrete
formed body was produced and evaluated in the same manner as in
Example 1, except that this monofilament was used as a fiber
material for cement reinforcement in place of a fiber bundled body.
The results are also shown in Table 1 (incidentally, some of the
evaluation results are also shown in Table 2 for comparison).
[0115] Next, an attempt was made to produce a concrete formed body
having an incorporation rate of the PVA monofilament fiber (fiber
material for reinforcement) increased from 1 vol % to 3 vol %.
However, the fibers were entangled after kneading, and separated
from the mortar component. The fluidity of the ready-mixed concrete
was 111 mm. In addition, it was not possible to normally place the
concrete in the mold. Therefore, the bending fracture energy and
compressive strength were not measured.
[0116] Thus, under the conditions where the incorporation rate of
the PVA monofilament fiber (fiber material for reinforcement) was 3
vol % as above, a mortar formed body was obtained using the
unhardened cement mortar having a water/binder ratio of 40.0% of
Reference Example 2 in place of the ready-mixed concrete having a
water/binder ratio of 19.2% of Reference Example 1, and evaluated.
The results are also shown in Table 2.
TABLE-US-00001 TABLE 1 Fiber Resin Component A Resin Component B
Fiber Material Material for Presence of Amount Presence Amount
Tensile Reinforcement Isocyanate Attached of Epoxy Attached
Strength Diameter Length Component [%] Component [%] [cN/dtex] [mm]
[mm] Example 1 Present 10 Present 3 21.0 0.45 30 Example 2 Present
10 Present 3 21.0 0.45 30 Example 3 Present 10 Present 3 21.0 0.45
30 Example 4 Present 10 Present 3 21.0 0.45 30 Example 5 Present 10
Present 3 21.0 0.45 30 Example 6 Present 10 Present 3 16.6 0.45 30
Example 7 Present 10 Present 3 12.0 0.45 30 Example 8 Present 10
Present 3 21.0 0.25 30 Example 9 Present 10 Present 3 21.0 0.45 15
Example 10 Present 10 Present 3 21.0 0.45 35 Example 11 Present 10
Present 3 21.0 0.45 30 Example 12 Present 10 Present 3 21.0 0.45 30
Comparative -- -- Present 13 21.0 0.45 30 Example 1 Comparative
Present 13 -- -- 21.0 0.45 30 Example 2 Comparative Absent 10
Present 3 21.0 0.45 30 Example 3 Comparative -- -- -- -- 6.9 0.66
30 Example 4 -- -- -- -- 6.9 0.66 30 Fluidity Fiber Material for of
Reinforcement Ready- Bending Incorporation Cohesion Mixed Fracture
Compressive Rate after Concrete Energy Strength [vol %] Cohesion
Kneading [mm] [N/mm.sup.2] [kN mm] Example 1 1 Excellent Excellent
275 211 32.1 Example 2 1 Excellent Excellent 268 203 18.2 Example 3
1 Fair Excellent 260 209 19.8 Example 4 1 Fair Excellent 259 213
18.4 Example 5 1 Fair Excellent 253 201 14.9 Example 6 1 Excellent
Excellent 267 209 20.5 Example 7 1 Fair Excellent 251 213 12.8
Example 8 1 Excellent Excellent 263 216 21.3 Example 9 1 Excellent
Excellent 279 213 20.5 Example 10 1 Excellent Excellent 253 201
34.5 Example 11 0.5 Excellent Excellent 278 217 10.7 Example 12 2
Excellent Excellent 252 197 49.2 Comparative 1 Poor Poor 153 199
8.2 Example 1 Comparative 1 Excellent Excellent 263 201 9.8 Example
2 Comparative 1 Poor Poor 131 195 7.6 Example 3 Comparative 1 -- --
270 199 7.4 Example 4 3 -- -- 111 Immea- Immea- surable surable
TABLE-US-00002 TABLE 2 Fluidity of Bending Incorporation Cohesion
Ready-Mixed Compressive Fracture Diameter Rate after Concrete
Strength Energy Fiber Material [mm] [%] Formed Body Kneading [mm]
[N/mm.sup.2] [kN mm] Example 1 Aramid fiber bundle 0.45 1 Concrete
formed body Excellent 275 211 32.1 Aramid fiber bundle 0.45 3
Mortar formed body Excellent 261 47 44.1 Comparative PVA
monofilament 0.66 1 Concrete formed body -- 270 199 7.4 Example 4
PVA monofilament 0.66 3 Mortar formed body -- 257 45 17.2
INDUSTRIAL APPLICABILITY
[0117] The fiber material for cement reinforcement of the invention
causes a smaller decrease in fluidity upon incorporation, and
allows for construction in the same manner as in the case where no
fibers are incorporated. In addition, high-durability concrete or
mortar having excellent mechanical characteristics can be
obtained.
* * * * *