Hydrophilic joint seal

Abstract: The present invention relates to a joint seal for use in joints that may be exposed to water, comprising at least one layer of a compressible impregnated open cell foam, on at least a portion of the surface of which is positioned a hydrophilic material.

Description: The present invention relates to the field of joint sealants. In particular, the present invention provides a novel compressible sealant with hydrophilic properties. The principle function of a joint sealant is to prevent the entry of water into the space between adjacent structural elements. The structural elements may be parts of a building, roadway, parking deck, bridge, or other engineering structure. They may be fixed relative to one another, or fairly mobile relative to one another. Waterproofing a joint between two relatively immobile elements is fairly straight forward, because fairly inflexible material can be utilized. However, even then, thermal expansion and contraction of the joint must be considered. Mobile joints, like expansion joints in bridge surfaces present greater problems, because they are expected to flex in three dimensions, and joints exposed to standing water, such as those found in drainage systems, or canals, must exhibit enhanced water resistance, as well as flexibility in many applications. Flexible, water resistant joint sealants have taken several forms. For instance, in Emseal Corporation's COLORSEAL tm and BACKERSEAL tm products, sealants composed of alternate layers of compressible and incompressible foam are utilized. Such sealants provide the flexibility inherent in compressible, usually impregnated forms and the moisture resistance of incompressible, closed cell foams (cf. US-A-5,935,695) which discloses a joint seal having the features of the preamble of claim 1. A limitation of such products is that under severe moisture conditions, or when exposed to standing water, moisture can penetrate between the foam layers. On the other hand, hydrophilic sealants, that expand to form a water tight plug when exposed to moisture, are also available. The drawback of these is that they are relatively inflexible, so generally have been found to be inappropriate for use in mobile joints. DE 40 20 230 A1 describes a joint caulking strip having an impregnated foam, wherein the impregnation comprises a first, water repellent component and a second hydrophilic component. The object of the present invention is to provide a joint sealant that combines the best properties of compressible foam and hydrophilic sealants. The sealant of the present invention is flexible enough to be used in mobile joints, and upon exposure to water will expand to firmly seal a joint. The present invention is a joint seal for use in joints that may be exposed to water, comprising at least two layers of a compressible impregnated open cell foam, sandwiching a third layer, wherein said third layer is a layer of hydrophilic material, positioned such that when said joint is exposed to a large amount of water, the hydrophilic material will swell, squeezing said open cell foam layers tight against the sides of said joint, and rendering said joint water-tight, even against significant pressures. Further preferred embodiments are disclosed in dependent claims 2 to 5. In drawings that illustrate the present invention by way of example: Figure 1 is a cross-sectional view of a joint seal according to a first embodiment of the present invention; Figure 2 is a cross-sectional view of the seal of Figure 1; Figure 3 is a cross-sectional view of the seal of Figure 1, installed in a joint; Figure 4 is a cross-sectional view of the seal installation of Figure 3, showing the hydrophilic portion thereof expanded; Figures 5, 6, 7 and 8 are views similar to Figure 3, of alternate embodiments of the joint seal of the present invention, installed in a joint. Referring now to Figures 1 - 4, a joint seal 1 of the present invention comprises, in its basic form, a layer of hydrophilic material 2 sandwiched between two layers of compressible open celled impregnated foam 3. Open celled impregnated foam 3, such as that sold under the trade marks GREYFLEX, 25V or 20H, by Emseal Corporation is suitable for use as layer 3. Layer 3, on its outer surfaces, may also have an adhesive applied thereto, to promote good adhesion to a joint surface, and to the surface of hydrophilic layer 1. As can be seen in figure 1, the seal is packaged in a precompressed format, preferably as shown with the foam layers compressed and held in compression by stiff boards 4 that are held in place by a layer 5 of shrink-wrap or tape. It may also be packaged in precompressed format on reels. In its uncompressed state, a typical seal will resemble that shown in Figure 2, where it can be seen that the impregnated open cell foam will expand to three or four times its compressed volume when released from compression. This property permits a tight seal to be achieved against the side surfaces of a joint, as shown in Figures 3 and 4. In Figure 4, a seal is shown installed in a joint, which is a squared channel formed in the upper surfaces of adjacent elements such as concrete slabs. The seal is installed in a clean joint, by being inserted therein with the upper edge of the seal preferably flush with the upper edge of the joint. The seal is unwrapped from its packaging, and pressed against one side surface of the joint at the correct height, where it will stick, due to the adhesive action of the adhesive on the exterior surface of foam layer 3, or by means of an adhesive reapplied to both faces of the joint or layer 3. When the compressed foam layers 3 expand, the seal will fill the joint, as shown in Figure 3. If the joint is exposed to a large amount of water, as shown in figure 4, the hydrophilic layer 2 will swell, squeezing the foam layers 3 tight against the sides of the joint, and rendering the joint water tight, even against significant pressures. It is important to note that the hydrophilic layer alone, in the absence of the compressible foam layers provided by the present invention, is of limited utility as a joint seal, as it will tend to extrude from a joint if over swollen, as it is unconfined in a joint. Suitable hydrophilic compounds are sold under the trade mark ADEKA ULTRA SEAL by Adeka Ultra Seal U.S.A., in sheets, tapes, strips, pastes, gels and liquids. Other appropriate hydrophilic compounds such as bentonite clay or sodium bentonite will be a matter of choice to one skilled in the art. Referring now to Figure 5, an alternative embodiment of the present invention, especially useful for application in wide joints is illustrated. The joint seal 1 shown in Figure 5 comprises outer layers of compressible adhesive impregnated foam 3 surrounding inner layers of hydrophilic material 2, with a core of non-compressible closed cell foam 6. The core of non-compressible foam acts as a fairly inflexible, impervious and inexpensive seal, permitting the use of smaller amounts of the flexible expanding layers which are more expensive, and less impervious to water. It will be understood that more than one layer of non-compresible foam may be used, interleaved with compressible foam and/or hydrophilic layers. Moreover, only one layer 2 of hydrophilic material may be provided, but the use of two layers improves the symmetry of the seal. The relative positions of the hydrophilic layers 2 and the foam layers 3 are interchangeable. Figure 7 illustrates an embodiment of the present invention using an incompressible closed cell core 6, sandwiched by two layers of compressible foam 3, partially impregnated with hydrophilic material 2, by spraying one or more surfaces thereof, or applying paste to the surfaces thereof. Other methods of impregnating the foam 3 with the hydrophilic material 2 will be obvious to one skilled in the art. The benefit provided by the Figure 7 embodiment is that when the hydrophilic material swells, it will make an effective waterstop, but does not tend to bulge out of the joint. The embodiment of figure 7 will find application in joints such as vertical joints between concrete panels in a curtain wall. In Figures 6 and 8, an alternative to the embodiment shown in Figures 1 - 4 is illustrated. In Figure 6, two layers of compressible adhesive impregnated foam 3 sandwich one or more strips 7 of hydrophilic material, embedded between the layers of foam. In Figure 8 four layers of foamed sandwich three layers of strips 7, which are staggered as to expand in a fairly rectangular direction. The function of the hydrophilic layers in this case is to act as a fail-safe, to ensure that if water does manage to penetrate between the layers of foam, as may be the case in extreme conditions, it is absorbed into the hydrophilic material, which when it expands, acts to further tighten the seal of the compressible foam. It will be understood from the foregoing that the combinations of layers of foam - both compressible and not - and hydrophilic materials can be developed without departing from the present invention, as defined by the appended claims.

Claims: A joint seal for use in joints that may be exposed to water, comprising at least two layers of a compressible impregnated open cell foam (3), sandwiching a third layer (2) characterized in that said third layer (2) is a layer of hydrophilic material, positioned such that when said joint is exposed to a large amount of water, the hydrophilic material (2) will swell, squeezing said open cell foam layers tight against the sides of said joint, and rendering said joint water-tight, even against significant pressures. The joint seal as claimed in claim 1, comprising two layers of said open celled foam (3), between which is embedded at least one strip (7) of hydrophilic material. The joint seal as claimed in claim 1 or 2, further comprising a core of non-compressible closed cell foam (6) sandwiched by two layers of hydrophilic material (2), onto the outer surfaces of which are adhered layers of said open cell foam (3). The joint seal as claimed in one or more of preceding claims 1 to 3, wherein said hydrophilic material (2) at least partially impregnates a surface of said foam (3). The joint seal as claimed in claim 4, including two layers of foam (3) at least partially impregnated with hydrophilic material (2), sandwiching a layer of incompressible closed cell foam (6).

Inventors: BAERVELDT KONRAD, BAERVELDT, KONRAD
Applicants: BAERVELDT KONRAD, BAERVELDT, KONRAD
Application year: 2001
Main classification: E04B1
IPC codes: E01C11, E04B1