Note: Descriptions are shown in the official language in which they were submitted.
CA 02333419 2000-11-24
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DESCRIPTION
METHOD OF REPAIRING AND REINFORCING EXISTING CONCRETE
STRUCTURE, AND RESIN
TECHNICAL FIELD
The present invention relates to a method of
repairing and reinforcing existing concrete structures
such as bridge footings, bridges, and pillars of building
structures.
This application is based on Japanese Patent
Application No. Hei 10-144249 filed in Japan, the content
of which is incorporated herein by reference.
BACKGROUND ART
As the method of repairing and reinforcing existing
concrete structures such as bridge footings, for example,
there has been known a method of casting an epoxy resin
into the space between a steel plate and concrete and
curing the epoxy resin, thereby bonding them. A method
of impregnating a reinforcement fiber sheet material
with an epoxy resin and applying the reinforcement fiber
sheet material to the surface of an existing concrete
structure has attracted special interest recently, and
actual results have increased gradually. This method
has such an advantage that haulage of heavy weights such
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as steel plate, assembling operation, and welding
operation are not required as compared with a method
of using a steel plate.
However, the epoxy resin used exclusively in
impregnation of the reinforcement fiber sheet material
had the following problems . That is, several days are
required to cure the epoxy resin, thereby securing
sufficient strength even at normal temperature.
Furthermore, when using no special heating means at low
temperature such as 5°C or lower, curing hardly proceeds,
thereby to drastically lengthen a term of works.
To solve these problems of the epoxy resin, there
has been suggested a method of using, as an impregnating
resin, a radically polymerizable resin capable of curing
even at low temperature such as about 5°C , particularly
cryogenic temperature such as about -10°C , because of
its high curing rate (e.g. Japanese Patent Publication
(A) Nos. Hei 9-184304, Hei 9-184305 and Hei 10-7750.)
A means of using the radically polymerizable resin
as the impregnating resin exerts excellent reinforcing
effect when using in combination with a reinforcement
fiber sheet material in the form suited for a radically
polymerizable resin. However, when using in
combination with reinforcement fiber sheet materials
developed by using, as the impregnating resin, an epoxy
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resin which has widely been used at present, for example,
reinforcement fiber sheet materials prepared by
unidirectionally arranging reinforcement fibers on a
substrate sheet through an adhesive layer (Japanese
Patent Publication (A) Nos. Hei 3-224901, Hei 3-222734
and Hei 5-32804 ) and reinforcement fiber sheet materials
prepared by impregnating reinforcement fibers with a
small amount (15% by weight or less) of a resin (Japanese
Patent Publication (A) Nos. Hei 7-34677 andHei 7-228714) ,
the curing in the vicinity of the reinforcement fibers
does not proceed sufficiently because of a difference
in method of reacting the resin, resulting in poor
repairing and reinforcing effect.
DISCLOSURE OF THE INVENTION
To solve the problems described above, the present
inventors have intensively studied and found that, by
using an additional impregnating resin having a
viscosity and a curing time within a specific range,
a sufficient reinforcing effect can be exerted even when
using a reinforcement fiber sheet material whose resin
content is 15 o by weight or less, which was developed
by using an epoxy resin as an impregnating resin. Thus,
the present invention has been accomplished.
That is, a first gist of the present invention lies
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in a method of repairing and reinforcing an existing
concrete structure, which comprises applying a
reinforcement fiber sheet material having a resin
content of 15 o by weight or less to the surface of the
existing concrete structure while being impregnated
with a resin having a viscosity within a range of 2. 5-300
poise and a curing time within a range of 1-24 hours,
and curing the resin.
A second gist of the present invention lies in a
method of repairing and reinforcing an existing concrete
structure, which comprises applying a reinforcement
fiber sheet material having a resin content of 15 o by
weight or less to the surface of the existing concrete
structure, impregnating the reinforcement fiber sheet
with a resin having a viscosity within a range of 2. 5-300
poise and a curing time within a range of 1-24 hours,
and curing the resin.
In the present invention, a resin (resin having
a viscosity within a range of 2.5-300 poise and a curing
time within a range of 1-24 hours), with which the
reinforcement fiber sheet material is impregnated
subsequently, is referred to as an additional
impregnating resin.
The additionalimpregnating resinisparticularly
preferably a radically polymerizable resin having a
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viscosity within a range of 10-100 poise and a curing
time within a range of 2-12 hours, which corresponds
to a third gist of the present invention.
According to the present invention, even when using
a reinforcement fiber sheet material having a resin
content of 15 o by weight or less, which was developed
by using an epoxy resin as an impregnating resin used
widely to repair_ and reinforce existing concrete
structures, the curing can be carried out very easily
in a comparatively short time within a day without
dependingonthetemperatureconditions. Theexecution
can be conducted even at low temperature and an excellent
reinforcing effect is exerted.
BEST MODE FOR CARRYING OUT THE INVENTION
(Reinforcement fiber sheet material - Resin)
In the method of repairing and reinforcing an
existing concrete structure of the present invention,
a reinforcement fiber sheet material comprising
reinforcement fibers and a resin whose content is limited
to 15'o by weight, which is preferably used in a repairing
and reinforcing method using an epoxy resin as an
impregnating resin, is used. .
The resin constituting the reinforcement fiber
sheet material may impregnate with the reinforcement
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fibers of the sheet material. Alternatively, the resin
may be in the form of an adhesive layer for bonding
arranged reinforcement fibers or woven reinforced
fibers with a release paper or a substrate sheet.
In the present invention, the resin constituting
the reinforcement fiber sheet material may be either
of a uncured thermosetting resin and a polymerized
thermoplastic resin and is not specifically limited,
but an epoxy resin containing no curing agent is
generally used. As a matter of course, the
reinforcement fiber sheet material may be a
reinforcement fiber sheet material which was specially
produced by fitting to the resin (additional
impregnating resin) with which the reinforcing resin
material is impregnated subsequently. When using, as
the additional impregnating resin, a radically
polymerizablemonomersuchasacrylateormethacrylate,
a resin having a solubility parameter (SP) value within
a range of 17-28 (MPa) 1~2, which is described hereinafter,
is preferably used as the resin constituting the
reinforcement fiber material.
It is necessary that the amount of the matrix resin
constituting the reinforcement fiber sheet material is
15% by weight or less. When the amount of the resin
exceeds 15o by weight, poor curing of the additional
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impregnating resin and deterioration of physical
properties of the cured article are caused, which is
not preferable. On the other hand, when the amount of
the resin constituting the reinforcement fiber sheet
material is 7 o by weight or less, sufficient curability
and sufficient strength of the cured article are obtained,
which is particularly preferable, even in case the resin
constituting the reinforcement fiber sheet material is
different from the resin which with the reinforcement
fiber sheet material is impregnated subsequently, for
example, the resinconstitutingthe reinforcementfiber
sheet material is an epoxy resin and the reinforcement
fiber sheet material is subsequently impregnated with
a radically polymerizable resin. The amount of the
resin constituting the reinforcement fiber sheet
material is preferably to by weight or more because
handling properties of the reinforcement fiber sheet
material largely vary depending on the amount of the
resin. The resin constituting the reinforcement fiber
sheet material is preferably an uncured resin, or cured
resin having enough rigidity to conform to the place
having a curvature where the reinforcement fiber sheet
material is applied, or a cured resin having a shape
suited for the place, so that the reinforcement fiber
sheet material can be applied to the existing concrete
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g
structures having a curvature. As a matter of course,
when using the uncured resin, the shelf life at normal
temperature is preferably long.
(Reinforcement fiber sheet material - Reinforcement
ffibers)
Preferable examples of the reinforcement fibers
constituting the reinforcement fiber sheet material in
the present invention are fibers, which are generally
used as reinforcement fibers, such as carbon fibers,
aramid fibers, and glass fibers. Among these fibers,
carbon fibers are preferable.
The reinforcement fibers are preferably
high-strength carbon fibers having a tensile strength
of 4000 MPa or more when utilizing a strength, and more
preferably high-elasticity carbon fibers having an
elasticity of 250 GPa or more when utilizing an elastic
modulus.
When using carbon fibers as the reinforcement
fibers of the reinforcement fiber sheet material and
using a radically polymerizable resin as the resin for
subsequent impregnation, it is particularly preferable
to use carbon fibers using, as a sizing agent, a compound
having a radically polymerizable functional group at
at least one terminal in view of attainment of t=he
strength of the cured article.
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(Reinforcementfibersheetmaterial- Reinforcingform)
In the present invention, the reinforcing form in
the reinforcement fiber sheet material is not
specifically limited, but includes unidirectional
arrangement of the reinforcement fibers, or production
of sheet from a woven fabric made of the reinforcement
fibers. In view of the repairing and reinforcing effect,
the weight of the reinforcement fibers is preferably
150 g/m' or more.
As the form used preferably as the reinforcement
fiber sheet material used in the present invention, for
example, the following forms (1) to (3): (1) a
reinforcement fiber sheet material produced by
unidirectionally arranging reinforcement fibers or
weaving the reinforcement fibers to forma reinforcement
fiber woven fabric, forming the reinforcement fiber
woven fabric into a sheet having a weight of
reinforcement fibers of 150 g/m2, and impregnating the
sheet with a resin described above, (2) a reinforcement
fiber sheet material produced by laminating a glass fiber
fabric on at least one surface of the reinforcement fiber
sheet material ( 1 ) , and ( 3 ) a reinforcement fiber sheet
material produced by unidirectionally arranging
reinforcement fibers on a substrate sheet through an
adhesive layer are preferable as described in Japanese
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Patent Application (A) Nos. Hei 3-224901, Hei 3-222734,
Hei 5-32804, Hei 7-34677, and Hei 7-228714.
As the substrate sheet, for example, glass fiber
woven fabric, glass scrim cloth, glass fiber paper, glass
fiber nonwoven fabric, and nonwoven fabrics made of
fibers of various polymers such as polyamide and
polyphenylene sulfide are used.
The adhesive may be those capable of temporarily
bonding reinforcement fibers on a substrate and is
preferably made of a resin having good compatibility
with a matrix resin of the reinforcement fiber sheet
material . For example, when the matrix resin is an epoxy
resin, an epoxy adhesive is preferable
As a matter of course, the reinforcement fiber sheet
material used in the present invention is not limited
to the above reinforcement fiber sheet material and,
for example, there can be applied those obtained by
unidirectionally arranging reinforcement fibers or
weaving the reinforcement fibers, coating with a resin
constituting the reinforcement fiber sheet material in
a linear or dot form, thereby retaining the form, or
those obtained by further laminating a substrate sheet
thereon.
(Additional impregnating resin)
In the present invention, the reinforcement fiber
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sheet material is impregnated with a curable resin on
or after application of it on the surface of an existing
structure. In the present invention, it is necessary
to use a resin having a viscosity within a range of 2 . 5-300
poise and a curing time within a range of 1-24 hours
as the additional impregnating resin in order to enhance
the repairing and reinforcing effect by using the above
reinforcement fiber sheet material.
The viscosity of the resin used for impregnation
is a viscosity measured at the execution temperature
using a B type viscometer, or a viscosity measured before
adding an organic peroxide which serves as a
polymerization initiator in case the resin used for
impregnation is a radically polymerizable resin. When
the viscosity of the resin exceeds 300 poise, it becomes
difficult to impregnate the reinforcement fiber sheet
material with the resin. On the other hand, when the
viscosity is less than 2.5 poise, the reinforcement
fibers are liable to move during the impregnation and
curing process of the resin, thereby lowering the
reinforcing effect in a combination with the
reinforcement fiber sheet material. The lower limit
of preferable viscosity is 10 poise, while the upper
limit thereof is 100 poise.
As used herein, the term "curing time" refers to
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a time from the beginning of the curing of the resin
to the point of time where a tacky feel on touch with
fingers disappears. When using a resin having the
curing time of one hour or less, sufficient strength
is hardly attained. When using a resin whose curing
time exceeds 24 hours, the resin is not suited for the
purpose of the present invention because of its too long
curing time.
The lower limit of the curing time is more
preferably 2 hour or more, while the upper limit is more
preferably 12 hours or more, and most preferably 8 hours
or less.
The resin may be a resin which satisfies the
requirements of the viscosity and curing time. A
thermosetting resin is preferable and a cold curing resin
isparticularlypreferable. A radicallypolymerizable
resin is particularly preferable in view of the
low-temperature curability, and a radically
polymerizable resin composed of a radically
polymerizablemonomeroroligomerhavinga methacryloyl
group or an acryloyl group as a reactive group at terminal
is particularly preferable in view of balance between
the curability and attainment of physical properties
of the cured article.
The composition may be a composition containing
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a monomer having a terminal reactive group other than
the methacryloyl or acryloyl group, for example, styrene
as far as it satisfies the requirements of the viscosity
and curing time.
Examples of the radically polymerizable monomer
include acrylate, for example, methyl acrylate and ethyl
acrylate, methacrylate, for example, methyl
methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl
methacrylate, and tetrahydrofurfuryl methacrylate,
styrene, vinyltoluene, divinylbenzene, and
acrylonitrile, and these monomers can be used alone or
in combination according to the purposes. Among these
monomers, acrylate and methacrylate are particularly
preferable in view of the curablity and attainment of
the strength.
Since the radically polymerizable monomer in the
present invention is preferably a monomer which is
compatible with a resin adhered to the reinforcement
fiber sheet to some extent, a radically polymerizable
monomer having a solubility parameter (SP) value within
a range of 17-22 (MPa)1~2 is particularly preferable.
The SP value of the radically polymerizable monomer
can be calculated by the equation: SP - E (Wn/100SPn)
[Wn: weight percentage of n monomer, SPn: SP value of
n monomer].
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Examples of the radically polymerizable oligomer
include, but are not limited to, polyester
poly(meth)acrylate obtainedbyintroducing an acryloyl
group or a methacryloyl group into terminal of an
oli.gomer, which is obtained by reacting a polybasic acid
such as phthalic acid or adipic acid with a polyhydric
alcohol such as ethylene glycol or butanediol, by the
reaction with acrylic acid or methacrylic acid; allyl
group-containing polyester (meth)acrylate obtained by
reacting a polybasic acid, a polyhydric alcohol, an allyl
group-containing alcohol such as pentaerythritol
triallyletherortrimethylolpropanediallylether,and
a (meth)acrylate; allyl group-containing polyester
obtained by reacting a polybasic acid, a polyhydric
alcohol, and an allyl group-containing alcohol; epoxy
poly (meth) acrylate obtained by reacting an epoxy resin
with a (meth) acerylate; and urethane poly (meth) acrylate
obtained by reacting a polyol, a polyisocyanate, and
a hydroxyl group-containing (meth)acrylate.
The molecular weight of the radically
polymerizable oligomer used in the present invention
is not specifically limited, but is more preferably 10000
or less in terms of a number-average molecular weight
in view of the curability at low temperature.
As a matter of course, an elastomer component having
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a reactive functional group at terminal, as a reactive
oligomer, can be added to provide high toughness and
durability with the cured article.
The mixing ratio of the monomer to the oligomer
in the impregnating resin used in the present invention
is not specifically limited as far as it satisfies
limitation of the viscosity and curing time of the
composition.
Examples of an initiator used for initiating t=he
polymerization of these radically polymerizable
monomers and oligomers include commonly used curing
agents, for example, redox catalysts prepared by using
a peroxide in combination with a curing accelerator such
as metal soap or tertiary amine. The combination is
selected so that the curing time becomes one hour or
more and 24 hours or less, preferably 12 hours or less.
For the purpose of adjusting the viscosity of the
compositionandimprovinghightoughnessanddurability
of the cured article, a polymer is added in place of
or in addition to the oligomer as the impregnating resin.
Preferable polymers include, but are not limited to,
elastomer polymers such as acrylic polymer,
acrylonitrile-butadiene rubber, acrylic rubber,
styrene block polymer, and urethane elastomer. The
amount of the polymer is not specifically limited as
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far as it satisfies limitation of the viscosity and
curing time of the composition, but is preferably 500
by weight or less in most cases.
It is preferable to contain a radically
polymerizable monomer and a non-reactive polymer as a
principal component because the viscosity of the resin
can be properly controlled.
It is more preferable to contain a radically
polymerizable monomer, a radically polymerizable
oligomer having a number-average molecular weight of
10000 or less and a non-reactive polymer as a principal
component because the reactivity and viscosity of the
resin can be properly controlled.
The radically polymerizable resin in the present
invention can be incorporated with agents capable of
imparting thixotropy, agents capable of imparting
air-curability, coupling agents, polymerization
inibitors and colorants according to the purposes, in
addition to the monomers, oligomers, polymers and curing
agent components described above.
Examples of the agent capable of imparting
thixotropy include, but are not limited to, finely
powdered silica such as "AEROSIL 200" manufactured by
Nippon Aerosil Co. , Ltd. , "NIPSEAL LP" manufactured by
Nippon Silica Industries Co., Ltd.; finely powdered
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calcium carbonate such as "HAKUENKA CC" manufactured
by Shiraishi Calcium Co., Ltd. and "NANOX 25"
manufactured by Maruo Calcium Co., Ltd.; and powdered
organic matter such as "DISPARLON 305" manufactured by
Kusumoto Chemical Company. The amount of thereof is
o by weight or less, and usually 5 o by weight or less .
Typical examples of the agent capable of imparting
the air-curability include higher fatty acids such as
paraffin wax represented by n-paraffin, polyethylene
wax, and stearic acid. Commercially available
compounds having an air drying function, for example,
monoepoxy compound such as glycidyl methacrylate or
allyl glycidyl ether, acrylic acid derivative of
dicyclopentadiene, and "RIPOXY AC-201" manufactured by
Showa Highpolymer Chemicals Co. , Ltd. can be used alone
or in combination. The amount of the agent capable of
imparting the air-curability is preferably within a
range of 0.1-10o by weight based on the resin for
impregnation. When the amount is less than O.lo by
weight, sufficient air-curability can not be obtained.
On the other hand, when the amount exceeds 10 o by weight,
the physical properties of the cured article are liable
to be lowered. When using higher fatty acid such as
paraffin wax, the amount is particularly preferably
within a range of 0.1-5% by weight based on the resin
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for impregnation.
The resin used in the present invention can be
optionally mixed with coupling agents, for example,
silane coupling agent such as y
-methacryloxypropyltrimethoxysilane, titanate
coupling agent, zirconate coupling agent, and
organoaluminum coupling agent alone or in combination.
The amount is preferably within a range of 0. 5-5 parts
by weight based on 100 parts by weight of the resin for
impregnation.
The resin used in the present invention is
preferably incorporated with a sufficient amount of
polymerization inhibitors to secure the stability
during the circulation. If necessary, colorants,
pigments and defoamers can be added.
In the present invention, the amount of the
additional impregnating resin, with which the
reinforcement fiber material is impregnated, may be an
enough amount to form a composite wherein the
reinforcement fiber sheet and additional impregnating
resin are integrated with each other after impregnation,
but is not specifically limited.
(Execution procedure of repair and reinforcement)
The execution procedure for repair and
reinforcement of the existing concrete structure in i~he
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present invention will be described.
In the present invention, the repair and
reinforcement of the existing concrete structure can
be carried out by applying the reinforcement fiber sheet
material described above to the surface of an existing
concretestructurewhileimpregnatingthereinforcement
fiber sheet material with a resin, or applying t=he
reinforcement fiber sheet material to the surface of
the existing concrete structure and impregnating w;~th
the resin, and curing the resin. In this case, the place
where the reinforcement fiber sheet material is applied
may be previously coated with an impregnating resin
beforeapplyingthe reinforcementfibersheet material.
It is preferable to previously repair the surface
of the existing concrete structure, on which the
reinforcement fiber sheet material is applied, by
smoothly grinding unevenness, difference in level,
defect portions, and cracks using a grinder, or filled
them with putty or pour in view of the improvement in
application strength.
It is preferable that the surface of the existing
concrete structure, on which the reinforcement fiber
sheet material is applied, is optionally coated with
an adequate amount of a primer resin using a known means
such as a roller brush or spray after removal of the
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unevenness, and then the resin is cured. The primer
resin is preferably the same resin as the impregnating
resin used to apply the reinforcement fiber sheet
material is applied subsequently. The primer resin
having lower viscosity is more preferable in view of
the adhesion with concrete and workability, and the
primer resin is preferably a composition which is cured
more rapidly, that is, a composition which is cured in
about one hour. Such a primer resin mixed with a curing
agent and a curing accelerator immediately before use.
Examples of the acrylic primer resin which can be
used in the present invention include, but are not
limited to, ~~ACRYSYRUP DR-80" manufactured by
Mitsubishi Rayon Co., Ltd.
In the method of the present invention, the
impregnating resin is mixed with the curing agent and
curing accelerator immediately before use so as to obtain
a predetermined curing time.
More preferable repairing and reinforcing method
of the present invention includes, for example, a method
of coating the surface of an existing concrete structure,
on which a primer resin is coated, with the above
additionalimpregnatingresin,applyingareinforcement
fiber sheet material thereon, further coating with the
additional impregnating resin, impregnating the
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reinforcement fiber sheet material with the additional
impregnating resin while pushing out an air contained
in the sheet using a deaeration roller, and allowing
to stand, thereby curing the reinforcement fiber sheet
material.
According to the purposes, a repairing and
reinforcing layer can also be formed by laminating plural
reinforcement fiber sheet materials while changing the
fiber direction.
Finally, the reinforcement fiber sheet material
can be optionally coated with paint or mortar, as a matt=er
of course.
EXAMPLES
The present invention will be described in detail
by way of examples.
(Example 1)
(Synthesis of oligomer 1)
In a vessel equipped with a stirrer, a temperature
controller and a condenser, 148 parts by weight of
phthalic anhydride, 1227 parts by weight of methyl
methacrylate, 230 parts by weight of pentaerythritol
triallyl ether ("P-30M", manufactured by Daiso Co.,
Ltd.), 3.8 parts by weight of dimethylaminoethyl
methacrylate and 0.38 parts by hydroquinone monomethyl
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ether were charged, and then the mixture was reacted
at the reaction temperature of 85°C for three hours to
obtain a resin solution containing an allyl
group-containing carboxylic acid. Furthermore, 1943
parts by weight of a bisphenol A epoxy resin ("EPIKOTE
1004", manufactured by Yuka Shell Epoxy Co. , Ltd. ) , 86
parts by weight of methacrylic acid, 40 parts by weight
of dimethylaminoethyl methacrylate, 2 parts by weight
of hydroquinone monomethyl ether and 1227 parts by weight
of methyl methacrylate were added and the reaction was
conducted until the acid value became 8 (mgKOH/g) or
less by heating the reaction temperature to 90°C to
obtain an oligomer 1 containing 50 o by weight of methyl
methacrylate. The number-average molecular weight of
the composition obtained after removing the monomer
component from the resulting oligomer 1 was 2000.
(Preparation of impregnating resin)
To 100 parts by weight of a mixture (viscosity is
poise at 25°C ) of methyl methacrylate (SP value:
18) and an oligomer in a weight ratio of l:l, 1 part
by weight of n-paraffin as the component capable of
imparting air-curability, 1 part by weight of y
-methacryloxypropyltrimethoxysilane as the silane
coupling agent, 1 part by weight of cumene hydroperoxide
as the initiator and 1 part by weight of cobalt naphtenate
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as the curing accelerator were added.
(Production of reinforcement fiber sheet material)
Carbon fibers ("TR50", manufactured by Mitsubishi
Rayon Co., Ltd.) (Tensile strength: 4900 Mpa) coated
with a sizing agent, an epoxy ester ("3002M",
manufactured by Kyoei Fats and Oils Chemical Industries
Co. , Ltd. ) containing a bisphenol_ A derivative having
a methacrylic group at terminal as a principal component
were unidirectionally arranged so that the weight of
carbon fibers per 1 m2 became 300 g, and then impregnated
with an epoxy resin composition ("base resin for #350",
manufactured by Mitsubishi Rayon Co., Ltd., SP value:
23) containing no curing agent in an amount of 15 g per
1 m2 . Then, SCRIM CLOTH (manufactured by Nittobo ) havi.ng
a thickness of 25 ~ m as the substrate was laminated
thereon to obtain a reinforcement fiber sheet 1.
(Impregnation with resin / Curing)
The reinforcement fiber sheet 1 was impregnated
with the above impregnating resin in the resin amount
of about 400 g per 1 m2, and then allowed to stand in
an atmosphere at 25°C, thereby curing the resin. After
two hours, tack of the surface disappeared and the resin
was cured.
Test samples for tensile test were made from the
cured reinforcement fiber sheet material and the tensile
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strength in the direction of carbon fibers was measured.
The average tensile strength of the composite was 4100
MPa calculated based on 1000 carbon fibers.
The surface of a concrete sample based on JIS
(Japanese Industrial Standards)-A-1132 was coated with
an acrylic primer resin ("ACRYSYRUP DR-80",
manufactured by Mitsubishi Rayon Co., Ltd.) at 25'~C
using a brush in the amount of 200 g per 1 m2, and then
the reinforcement fiber sheet material 1 was applied
to the surface of the concrete sample in the same manner
as described above. After aging for one day, the bonding
test to the concrete was carried out in accordance with
JIS-A-6909. As a result, the strength was 2 . 4 MPa and
the fracture mode corresponded to material fracture in
concrete.
(Example 2)
In the same manner as in Example l, except that
the above oligomer 1 and an epoxy oligomer ( "EPOXY ESTER
3000M", manufactured by KyoeiSha Kagaku Co., Ltd.,
hereinafter referred to as an oligomer 2 ) were used in
combination as the oligomer and each proportion of the
respective components was changed as shown in Table l,
the operation was conducted. The evaluation results
are shown in Table 1.
(Example 3)
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In the same manner as in Example 2, except that
the amount of the curing accelerator was reduced to half,
the operation was conducted. The evaluation results
are shown in Table 1.
(Example 4)
(Synthesis of oligomer 3)
In a vessel equipped with a stirrer, a temperature
controller and a condenser, 583 parts by weight o.f a
bisphenol A epoxy resin "EPIKOTE 1004", manufactured
by Yuka Shell Epoxy Co., Ltd.), 43 parts by weight of
acrylic acid, 6.2 parts by weight of dimethylaminoethyl
methacrylate, 0.62 parts by weight of hydroquinone
monomethyl ether and 633 parts by weight of methyl
methacrylate were charged, and then the mixture was
reacted at the reaction temperature of 90°C until the
acid value became 5 (mgKOH/g) or less to obtain an
oligomer 3 containing 50o by weight of methyl
methacrylate. The number-average molecular weight of
the composition obtained after removing the monomer
component from the resulting oligomer 3 was 2300.
(Preparation of impregnating resin)
In the same manner as in Example l, except that
an oligomer 3 was used as the oligomer component in place
of the oligomer 1 and each proportion of the respective
components was changed as shown in Table l, the operation
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26
was conducted. The evaluation results are shown in
Table 1.
(Example 5)
In the same manner as in Example l, except that
an acrylic resin (~~DIANAL BR-83", manufactured by
Mitsubishi Rayon Co., Ltd.) caas used in place of the
oligomer 1 and each amount of the respective components
was changed as shown in Table l, the operation was
conducted. The evaluation results are shown in Table
1.
(Example 6)
In the same manner as in Example 5, except that
the amount of the curing accelerator was reduced to half,
the operation was conducted. The evaluation results
are shown in Table 1.
(Comparative Example 1)
The monomer component and oligomer component were
mixed in the proportion shown in Table 1 to prepare a
resin composition whose viscosity is 2 poise at 25°C
and the same operation was conducted in the same manner
as in Example 1. The evaluation results are shown in
Table 1. The curability of the impregnating resin was
excellent and the adhesion with concrete was good, but
the tensile strength of the composite was poor such as
3720 MPa.
CA 02333419 2000-11-24
27
(Examples 7 and 8)
Using the same impregnating resin as in Comparative
Example l, a test was conducted by changing the
temperature, at which a sample is made, to 5 and -10°C ,
respectively.
In this case, the amount of the curing accelerator
was changed as shown in Table 1 so that the curing time
became five hours. The viscosity of this composition
was 15 poise at 5°C, and 45 poise at -10°C .
The results are shown in Table 1 . With the decrease
of the temperature at which a test piece is made, the
viscosity of the resin increased, thus attaining
sufficient tensile strength.
(Comparative Example 2)
The curing agent of the resin composition used in
Comparative Example 1 was changed and the resin
composition was prepared so that the curing time became
30 minutes . The evaluation results are shown in Table
1. The tensile strength of the composite further
decreased.
(Comparative Example 3)
We made a trial of mixing the monomer component
and polymer component in the proportion shown in Table
1 to prepare a resin composition having a viscosity of
400 poise at 25°C and carrying out the same test.
CA 02333419 2000-11-24
28
However, it was difficult to carry out an operation of
impregnating a reinforcement fiber sheet with a resin
so that the subsequent evaluation could not carried out.
CA 02333419 2000-11-24
29
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CA 02333419 2000-11-24
Abbreviations in Table 1 denote the following substances,
respectively.
MMA: methyl methacrylate
2-EHA: 2-ethylhexyl acrylate
PEGA: phenoxyethylene glycol acrylate
CHPO: cumene hydroperoxide
BPO: benzoyl peroxide
NC: cobalt naphthenate
DMPT: N,N-dimethyl-p-toluidine
n-P: n-paraffin
yMX: y-methacryloxypropyltrimethoxysilane
Ol: oligomer 1
02: oligomer 2, epoxy oligomer ("EPOXY ESTER 3000M",
manufactured by KyoeiSha Kagaku Co., Ltd.)
03: oligomer 3
Pl: acrylic resin ("DIANAL BR-83", manufactured by Mitsubishi
Rayon Co., Ltd.)
(Comparative Example 4)
60 Parts by weight of a bisphenol A epoxy resin "EPIKOTE
828", manufactured by Yuka Shell Epoxy Co., Ltd.), 40 parts
by weight of trimethylolpropane triglycidyl ether ("ADEKA
GLYCEROL ED-505", manufactured by Asahi Denka Kogyo K. K. ) and
45 parts by weight of an aliphatic polyamide curing agent
("ANCAMINE 2021", manufactured by ACI Japan Co.) were mixed
CA 02333419 2000-11-24
31
to prepare a cold curable epoxy resin composition. The
viscosity of this composition was 50 poise at 25°C.
The reinforcement fiber sheet used in Example 1 was
impregnated with this epoxy resin composition to make a test
piece of the composite. The tackiness of the resin disappeared
after allowing to stand for 12 hours, but seven days caere
required to attain sufficient strength and elasticity. The
tensile strength evaluated after seven days was 4200 MF?a.
We made a trial of carrying out the same test at 5°C,
but gave up because the resin could not be cured.
(Example 9)
In the same manner as in Example l, except that 100 parts
by weight of a vinyl ester resin (RIPOXY R-840" manufactured
by Showa Highpolymer Chemicals Co. , Ltd. , viscosity at 25°C:
25 poise, SP value: 19) as the impregnating resin, 1 part by
weight of a curing catalyst ("CH", manufactured by Showa
Highpolymer Chemicals Co. , Ltd. ) and 0. 3 parts by weight of
cobalt naphthenate as the curing accelerator, the operation
was conducted. The curing time was three hours at 25°C . The
surface tack disappeared at all after six hours have passed
since the impregnation of the reinforcement fiber sheet
material with the resin, and the tensile strength of the
composite was 4020 MPa.
(Example 10)
In the same manner as in Example 9, except that 2 parts
CA 02333419 2000-11-24
32
by weight of methylethyl peroxide as the curing agent and 1
part by weight of cobalt naphthenate as the curing accelerator
were used relative to 100 parts by weight of the resin, the
operation was conducted. The curing time was one hour at 25°C,
and the tensile strength of the composite obtained after six
hours was 3000 MPa.
(Example 11)
In the same manner as in Example 7, except that a n-butyl
acrylate oligomer having a number-average molecular we=fight
of 6000, which has a methacryl group at one terminal, was used
in place of phenoxyethylene glycol acrylate, the test was
conducted. The viscosity of this resin was 5 poise at 5°C.
After six hours, the tackiness of the surface of the
sample thus obtained disappeared and the low-temperature
curability was also good. The tensile strength of the
composite was 4100 MPa and the fracture mode in the adhesion
test corresponded to material fracture of concrete.
(Example 12)
In the same manner as in Example l, except that ~~CONWOOD
NET ON5050" (weight of 7 g/m2) manufactured by Nisseki Pallet
System Co. , Ltd. was used in place of ~~SCRIM CLOTH" manufactured
by Nittobo, a reinforcement fiber sheet 2 was made. In the
same manner as in Example 3, a combination of this reinforcement
fiber sheet material and the resin used in Example 3 was operated.
The resulting composite attained sufficient tensile strength
CA 02333419 2000-11-24
33
such as 4300 MPa.
(Example 13)
In the same manner as in Example l, except that
high-elasticity carbon fibers having an elastic modulus of
392 Gpa ("HR40" manufactured by Mitsubishi Rayon Co., Lt_d.,
tensile strength: 4610 MPa) were used as the carbon fibers
and the resin composition used in Example 3 was used as the
resin composition, a resin composition was obtained and the
tensile strength of the composite was evaluated. The
resulting composite attainedsufficient strength such as4050
MPa.
(Example 14)
In the same manner as in Example l, except that ~~FOLKA
SHEET FTS-Cl-30" (SP value of used resin: 23) manufactured
by Tonen Co. , Ltd. in the form where reinforcement fibers are
unidirectionally arranged on a substrate sheet through an
adhesive layer was used as the reinforcement fiber sheet and
the resin used in Example 3 was used as the impregnating resin,
a resin composition was obtained and the tensile strength of
thecompositewasevaluated. Theresultingcompositeattained
sufficient strength such as 4300 MPa.
INDUSTRIAL APPLICABILITY
According to the present invention, existing concrete
structures such as bridge footings and buildings can be
CA 02333419 2000-11-24
34
repaired and reinforced easily in a short time without being
influenced by temperature conditions on execution, while
providing concrete structures with high strength. In
particular, existing reinforcement fiber sheet materials can
be effectively used.
