Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Noninterengaged fiber-containing paper-free web or sheet...
Reexamination Certificate
1998-04-29
2002-05-14
Copenheaver, Blaine (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Noninterengaged fiber-containing paper-free web or sheet...
C428S112000, C428S114000, C156S094000
Reexamination Certificate
active
06387479
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a repair and reinforcement method for preexisting structures such as bridge columns, piers, bridges, and buildings, and in particular, relates to a repair and reinforcement method for concrete structures, and to an anisotropic textile used in this method.
BACKGROUND ART
The repair and reinforcement of preexisting structures comprising concrete such as bridge columns, piers, bridges, and the like by the use of a unidirectional sheet material, in which carbon fibers, glass fibers, or high strength organic fibers are arranged in one direction, these are impregnated in advance with a small amount of resin, and are restricted in the weft direction and the thickness direction, or common textile materials, wherein these are affixed to the structures while impregnating with resin, and are then left to cure, is generally known.
In this case, cold-curing type epoxy resins, which have a long period of use and are comparatively easily handled, are most broadly employed as the matrix resin which is impregnated into the sheet material.
Furthermore, repair and reinforcement methods are also known in which, in order to shorten the work period at the site and to obtain stable properties, a so-called prepreg, which has been impregnated in advance with an appropriate amount of resin, is affixed, and this is then cured.
However, when the cold-curing epoxy resin which is commonly employed as a matrix resin in this field is used, although this is termed a cold-curing resin, the curing properties decline markedly below 10° C. and in particular below 5° C. and this leads to defects in curing and this leads to a lengthening of the execution period.
On the other hand, there has been much consideration given to the use of reinforcing materials (hereinbelow referred to as sheet materials) which form fiber-reinforced resin with resin. When a textile material comprising common reinforcement fibers is employed, the fibers run in two directions, so that the strength in one direction is less than half, and this is extremely disadvantageous when strengthening is particularly to be carried out in one direction, so that the use of a variety of unidirectional sheet materials has been considered.
(1) Use of Reinforcement Fiber Bundles
A technique in which reinforcement fiber bundles are wrapped around spots to be repaired and reinforced in preexisting structures while resin is being applied thereto is disclosed in Japanese Patent Application, First Publication No. Sho 62-33973 and Japanese Patent Application, First Publication No. Sho 62-244979.
(2) Use of a So-called Prepreg in which Resin is Impregnated in Advance into Reinforcement Fibers
A technique in which a sheet material, in which a net-shaped material is applied to a prepreg, in which reinforcement fiber bundles are arranged and impregnated with resin so that the amount of resin contained is 15 weight percent or less, is applied to portions to be repaired or reinforced of preexisting structures, and curable resin is applied and impregnated from the surface thereof, is disclosed in Japanese Patent Application, First Publication No. Hei 7-228714.
(3) Use of Reinforcement Fiber Cloth in which Resin is Not Impregnated in Advance into the Reinforcement Fibers
A technique in which a screen shaped sheet material in which carbon fibers are woven horizontally and vertically is applied to spots to be repaired and reinforced of preexisting structures, and a curable resin is applied and impregnated from the surface thereof, is disclosed in Japanese Patent Application, First Publication No. Sho 63-201269.
(4) Use of a Material which can be Positioned Between That of (2) and (3) A technique in which a sheet material, in which arranged reinforcement fiber bundles are applied to a supporting sheet via an adhesive layer, is applied to spots to be repaired and reinforced of preexisting structures, and a curable resin is applied and impregnated from the surface thereof, is disclosed in Japanese Patent Application, First Publication No. Hei 3-224901, Japanese Patent Application, First Publication No. Hei 4-149366, and Japanese Patent Application, First Publication No. Hei 5-32804.
However, in technique (1) above, in order to impregnate the reinforcement fiber bundles with resin and to wrap these around spots to be repaired and reinforced, it is necessary to use a dedicated-wrapping machine, and work is required to bring this machine to the site, and it is also difficult to use such a machine at sites for repair and reinforcement having a variety of conditions.
Furthermore, the sheet material which is employed in the technique described in (2) above is a sheet-shaped material in which, in order to ensure good handling properties during the carrying out of repairs, slightly more resin is applied to the reinforcement fibers than in the case of the level of a common sizing agent, the gaps between fibers are restricted, and a further net-shaped body is laid thereon, so that it is difficult to impregnate resin thereinto at the site in a short period of time, and it is not easy to use resin having a short period of use.
Furthermore, in the technique of (3) above, in the same way as in the case of a common textile material, a flat support body which is made unitary through the application of an amount of resin or an adhesive layer is not used; however, because of the severe restriction of the space between the reinforcement fibers themselves, the impregnation of resin is not easy, and resin having a short period of use cannot be employed.
Furthermore, in the technique described in (4) above, the arranged reinforcement fiber bundles are attached to a planar support body comprising a non-woven cloth or a net-shaped textile via adhesive layers, and this is made unitary, so that it is difficult to impregnate the resin in a short time at the site, and resin having a short period of use cannot be employed.
Furthermore, when sheet materials such as those described in (2) and (4) above are employed, when a resin having a low viscosity and great dissolving power such as an acrylic monomer or unsaturated polyester resins is impregnated, the resin which is to be impregnated is impregnated while dissolving the resin which was previously deposited in order to restrict the fibers, so that the fiber orientation becomes chaotic during the execution of the procedure, and it is impossible to obtain sufficient strength.
The present invention solves the problems described in the conventional art above; it has as an object thereof to provide a repair and reinforcement method for preexisting structures which is capable of execution even in poor conditions such as low temperature, and which is capable of exhibiting superior repair and reinforcement effects in a short period of time, as well as to provide an anisotropic textile which has superior handling properties and resin impregnation properties, and which also generates superior strength when hardened.
DISCLOSURE OF THE INVENTION
The present invention comprises a repair and reinforcement method for preexisting structures, wherein, during the repair and reinforcement of preexisting structures using a fiber-reinforced resin layer in which resin is impregnated into a sheet material comprising reinforced fibers and this resin is cured, the resin which is employed is a reactive mixture having a gelling time at 20° C. of 15 minutes or more and which initiates polymerization even at 5° C., and is curable in a period of time 6 hours less even at 5° C., and which has as the chief components thereof (1) a monomer having vinyl groups and (2) a reactive oligomer and/or a thermoplastic polymer having vinyl groups; and an anisotropic textile, having as the warp thereof a high strength and highly elastic fiber having a tensile strength of 3 GPa or more and a tensile elastic modulus of 150 GPa or more, and a fiber having a tensile elastic modulus lower than that of the warp as the weft thereof, wherein the weft comprises a compound thread having a weight of 0.1 g or less per one meter of fiber and comprising two types
Aoki Toshikazu
Fukumoto Masayuki
Hayashi Shigetsugu
Konishi Hideo
Sano Tomowo
Mitsubishi Rayon Co. Ltd.
Pratt Christopher C.
LandOfFree
Method of repairing/reinforcing existing structures and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of repairing/reinforcing existing structures and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of repairing/reinforcing existing structures and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2817280