Static structures (e.g. – buildings) – Machine or implement
Patent
1990-11-15
1992-10-20
Scherbel, David A.
Static structures (e.g., buildings)
Machine or implement
60527, 156 94, 52743, 52173R, 52514, F03G 706
Patent
active
051559650
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of injecting a repairing agent into cracks occurring in concrete or a base rock, a masonry joint of brick masonry and rock masonry, or the like, to repair the cracks.
BACKGROUND ART
As known well, concrete is a composite material which utilizes the fact that, when water is added to gravel, sand and cement and is kneaded together with the latter, the water and the cement are hardened under hydration reaction. Since the concrete is long in durability, and is high in strength and, further, is low in cost, the concrete is widely used in various fields. Particularly, the concrete is a material which is essential for buildings and civil engineering construction. However, the concrete alone is extremely low in bending strength and tensile strength, and cannot sufficiently stand up against a bending force and a tensile force. In order to strengthen or reinforce this disadvantage, a method has been invented which utilizes concrete reinforced with steel products. It is the existing condition that the compound of the concrete and the steel products is widely utilized for many buildings as reinforced concrete or steel concrete.
It cannot be avoided that, as a basic property of the concrete dry shrinkage occurs due to evaporation of excess mixed water during hardening, and many minute cracks are generated at various locations. The cracks per se are elucidated in view of structural mechanics, to be of no problem. However, secondary influences caused by the cracks, for example, leaking of rain in a concrete building, corrosion or erosion of reinforcement due to leaking water from cracks, reduction in structural strength caused by the corrosion, and the like, are so serious as to down grade a material value of the concrete. Accordingly, when cracks occur in the concrete or the reinforced concrete, it is essential to repair the cracks. Conventionally, the following repairing methods are employed.
Repairing methods normally practiced conventionally are divided broadly into two categories, depending upon the size or dimension of the cracks.
The first method is one which is employed in the case where crack width is relatively wide such as those above a value of the order of 1 mm, and a repairing material can easily be poured into the cracks. In the method, a concrete surface is cut out in the form of a letter x or x along the cracks, a repairing agent such as cement milk, mortar or the like is poured into the cracks by the use of a simple appliance and, subsequently, the cut-out portions are filled up by cement mortar or resin mortar, to repair the cracks.
The second method is one in which various injection appliances are used to inject, under pressure, a repairing agent such as resin or the like into cracks. The method is utilized in the case where the crack width is of the order of 1 mm or less, and the repairing material like one described above cannot easily be poured into the cracks. In this case, the narrower the crack width, and the deeper the depths of the cracks, the larger the injection resistance. Accordingly, various appliances are used which are so contrived that elastic springs, hydraulic pressure or pneumatic pressure, or rubber elasticity is utilized to produce a predetermined injection pressure. Various examples of the appliances are shown in FIGS. 12 through 15.
An appliance illustrated in FIG. 12 is one in which an elastic force of a rubber tube is utilized to produce injection pressure. The arrangement is such that a resin (a repairing agent) 2 is forced into a rubber tube 1 by a grease pump to inflate the rubber tube 1 like a balloon, and a contractile force of the rubber tube 1 causes the resin 2 to be injected into the cracks.
An appliance illustrated in FIG. 13 is one which is arranged such that a resin is put in a cylinder 3 in the form of an injector or syringe made of a plastic material, and a contractile force of rubber straps 4 and 4 causes a piston to be pushed into the cylinder to inject the resin.
An appliance illustrated in FIG. 14
REFERENCES:
patent: 3734348 (1973-05-01), White
patent: 4120128 (1978-10-01), Pauls
patent: 4622085 (1986-11-01), Yamada et al.
patent: 4811564 (1989-03-01), Palmer
Shimizu Shigeo
Tabei Kazuhiko
Mitsubishi Materials Corporation
Scherbel David A.
Shimizu Shigeo
Wood Wynn E.
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