JP5426298B2 - Flooring method and its floor structure - Google Patents

Description

  The present invention relates to a flooring laying method for laying a flooring material on a lower ground of a concrete floor across a stretch joint formed to absorb thermal expansion and contraction, and a floor structure thereof.

  Made of soft synthetic resin for building passageways, balconies, rooftops, and indoor floors to improve floor waterproofing, slip resistance, sound insulation, heat insulation, aesthetics, and prevent injury from falling. It is common to bond and fix flooring materials.

  When the building is a concrete structure such as an apartment, expansion joints are formed so that the concrete surface does not crack or collapse due to thermal expansion and contraction of the concrete frame. Also, in open corridors of low-rise apartments, precast concrete plates may be placed and fixed on joists to form floors. The joints of such concrete plates are due to thermal expansion and contraction of the concrete plates. It is a stretch joint so that fluctuations can be absorbed. When the flooring is bonded and fixed to the concrete floor under these expansion joints, the joint joint width expands and contracts due to the thermal expansion and contraction of the concrete, and the flooring surface is whitened along the joints. When the splay spreads severely, the flooring material is torn off, and when the joint width is reduced, the flooring surface is swollen.

  In order to deal with such a problem, conventionally, as shown in FIG. 7, the edge of the floor materials 1, 1 is sandwiched between the expansion joints J without bonding and fixing the flooring 1 across the expansion joints J. The adhesive was fixed by cutting. In this case, although the above problem is solved, it is necessary to perform sealing treatment with the sealing material 7 on the end portion of the flooring material 1 in order to prevent the flooring material 1 from falling and to ensure waterproofness. In addition to increasing the time and labor of construction, it was not very desirable from the viewpoint of beauty. Further, since the expansion joint J is exposed, there is a problem that the heel of the pedestrian's shoes falls into the gap. In recent years, in order to improve the waterproof property of the concrete floor F, the number of cases in which the floor material 1 is bonded and fixed to the entire surface of the concrete floor F has been rapidly increasing. It was also a problem that it could not contribute to the improvement of performance.

  As a method of adhering and fixing the flooring material to the entire surface of the concrete floor, for example, an elastic sealant is filled and applied to and around the expansion joint provided at the joint, and the surface is covered with a coated flooring material via an FRP reinforcing layer. A joint processing method has been proposed (Patent Document 1).

  The above joint treatment method can be laid on the lower ground of the concrete floor across the stretch joint, so there is no need to cut the edge of the flooring or to apply a sealing treatment, and the floor of the concrete floor Since the material can be laid, the waterproof property was also good.

JP-A-10-037114

  However, the joint treatment method described above applies an epoxy resin-based primer to the ground under the concrete floor, fills and applies an elastic sealant around the expansion joint and its surroundings, or interposes reinforcing fibers in the FRP reinforcing layer. Because it is necessary to insert an FRP reinforcing layer between the coating floor material and the elastic sealing material, or to cut out the coating floor material by the amount of the FRP reinforcing layer, there are many procedures, and it cannot be said that the workability is good. This was also not preferable. Further, in the above-mentioned Patent Document 1, it is assumed that the coating floor material does not cause peeling or cracking as its operational effect, but this is presumed to be due to the small amount of joint expansion and contraction, and the present invention. If it is adopted in a concrete floor having an expansion joint that is assumed to be ± 0.1 to 3 mm, it is impossible to follow the expansion and contraction, and it remains doubtful whether such an effect can be achieved.

  The present invention has been made in view of the above-mentioned problems, and the problem to be solved is that even when the expansion / contraction dimension of the expansion joint is large, the flooring surface is less likely to be whitened, and the swelling is not conspicuous, and the expansion joint It is an object to provide a method for laying a flooring material having good workability and waterproofness and a floor structure capable of easily laying a flooring material on a concrete floor.

  In order to achieve the above object, a floor material laying method according to the present invention is a floor material laying method in which a synthetic resin floor material is laid on a lower ground of a concrete floor on which stretch joints are formed, Place the strip so as to straddle the joint, touch the outer edge of the strip on both sides of the concrete floor between the lower ground of the concrete floor and the back of the flooring, and under the concrete floor over the entire length of the strip A non-adhesive region that does not bond the ground and the back surface of the flooring material is provided, and a synthetic resin flooring material is bonded and fixed to the lower ground of the concrete floor across the expansion joint.

  In the floor material laying method of the present invention, it is preferable that the non-adhesion region is continuously provided between the inner side of the outer edge on both sides of the belt and the back surface of the floor material. Adhesive tape is attached to the location where the non-adhesion area is provided, and flooring adhesive that adheres and fixes the flooring to the ground floor of the concrete floor is used. It is more preferable to lay a flooring after the coating.

  Next, in the floor structure of the present invention, the floor material made of synthetic resin is used so that the floor material made of synthetic resin straddles the expansion joint by using any one of the above flooring laying methods on the ground below the concrete floor on which the expansion joint is formed. It is laid on the ground below the concrete floor.

  In the flooring method according to the present invention, the flooring made of synthetic resin is bonded and fixed to the lower ground of the concrete floor across the expansion joint, so that the flooring materials 1 and 1 are the same as the conventional flooring method shown in FIG. No need to cut the edge of the seal or seal the sealant 7, so the workability is good, and the stretch joint J is completely covered with flooring, so it is highly waterproof and the heel of the pedestrian shoe There is no worry of falling and falling. In addition, since only a belt member is newly required, the construction procedure can be reduced, and the cost can be reduced.

  When the flooring is directly bonded and fixed to the lower ground of the concrete floor without providing a belt, the stretching stress with respect to the stretching of the stretch joint concentrates on a part of the floor located just above the stretch joint. On the other hand, by placing the strip so as to straddle the stretch joint as in the present invention, the stretching stress of the stretch joint is divided into two on both sides of the outer edge of the strip, and the whitening phenomenon of the flooring or Swelling can be reduced. And since the non-adhesion region is provided outside the outer edge of the band, the stretching stress applied to the floor material is dispersed throughout the non-adhesion region without concentrating on a part, and the whitening phenomenon is unlikely to occur on the floor material surface, Swelling is less noticeable. In addition, when the non-adhesive area is not provided, when the joint becomes narrow due to the expansion and contraction of the joint, the outer edge of the belt body hits the adhesive layer between the floor material back surface or the base material surface and the floor material back surface, and the floor material back surface is In the present invention, since the non-adhesive region is provided outside the outer edge of the belt body, the outer edge of the belt body slides smoothly on the ground below the concrete floor, and is used as a floor material. No extra stress is applied. Therefore, even if the laying method of the present invention is adopted for a concrete floor having an expansion joint that is assumed to be ± 0.1 to 3 mm, the expansion and contraction can be sufficiently followed, and there is no fear of causing problems.

  In addition, the floor material laying method in which the non-adhesive region is continuously provided between the inner side of the outer edge on both sides of the belt body and the back surface of the floor material is provided between the base surface in contact with the outer edge of the belt body and the back surface of the floor material. Since the non-adhesive area is continuously provided between the inner side of the belt body outer edge and the back surface of the flooring material, the range in which the expansion and contraction stress is dispersed is increased, so that the flooring surface is less prone to whitening. Also, swelling can be made inconspicuous.

Furthermore, adhesive tape is attached to the location where the non-adhesive area is provided, and flooring adhesive that adheres and fixes the flooring to the ground under the concrete floor is applied to the ground under the concrete floor, over the adhesive tape, The floor material laying method that lays the flooring after it is applied on the adhesive tape prevents the adhesive for the flooring from coming into contact with the base surface or the outer edge of the belt. A non-adhesive region can be easily formed without being bonded and fixed to the back surface of the flooring. In addition, by sticking the adhesive tape, when applying the adhesive for flooring, or when pressing the flooring to the base surface in order to remove the air that was firmly bonded to the base surface and bite, It is possible to prevent the band from moving.
Note that the term “adhesion” here means adhesion fixation with a curable adhesive often used in flooring applications, and is different in concept from “adhesion” with a non-curable adhesive.

  Next, since the floor structure of the present invention is constructed by using a laying method that exhibits excellent effects as described above, even if the concrete floor is thermally expanded and contracted, it is difficult for whitening and swelling to occur on the floor material surface, Since the flooring is laid across the joints, the waterproof property is very good, and there is no worry that the heels of the pedestrian shoes fall into the gaps between the stretch joints.

It is sectional drawing explaining the laying method of the flooring which concerns on one Embodiment of this invention. It is a perspective view which shows the strip | belt body used with the laying method. It is the schematic which shows the floor structure constructed | assembled using the same laying method. It is sectional drawing explaining the laying method of the flooring which concerns on other embodiment of this invention. It is sectional drawing explaining the laying method of the flooring which concerns on other embodiment of this invention. It is sectional drawing explaining the laying method of the flooring which concerns on other embodiment of this invention. It is sectional drawing explaining the laying method of the conventional flooring.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  The floor laying method of the present invention shown in FIG. 1 improves the waterproofness, slip resistance, sound insulation, heat insulation, aesthetics, and prevents injuries during a fall. A method of laying a synthetic resin floor material 1 on a lower ground F1 of a concrete floor F on which a stretchable joint J is formed, such as a balcony, a rooftop, or an indoor floor surface, as shown in FIG. The floor material 1 is bonded and fixed to the lower ground F1 of the concrete floor F across J.

  The flooring 1 laid on the lower ground F1 of the concrete floor F is formed of a soft vinyl chloride resin or a polyolefin resin, has a thickness of 1 to 3 mm, and is laminated with a glass fiber layer as an intermediate layer or a non-woven fabric on the back surface. What laminated | stacked the layer is used suitably.

  The expansion joint J formed on the concrete floor F has a width of about 3 to 40 mm. As shown in FIG. 1, the expansion joint J is filled with a joint sealing material 5. As the joint sealing material 5, an elastic sealing material such as silicon, urethane, epoxy, or acrylic is preferably used. By forming the expansion joint J in the concrete floor F and filling the joint sealing material 5 in this way, the thermal expansion and contraction of the concrete floor F can be sufficiently absorbed, and the concrete floor F is cracked or crushed. Is preventing.

  Normally, when the flooring 1 is bonded and fixed to the lower ground F1 of the concrete floor F across the expansion joint J, the concrete floor F expands and contracts due to a temperature difference due to cold and warm. If the surface of the flooring 1 is whitened along the stretch joints J, the flooring 1 is torn off when the jointing width is severe, or the flooring 1 is shrunk. There arises a problem that the surface is swollen. In order to cope with this problem, the floor material laying method according to the present invention is such that the belt 2 shown in FIG. 2 is placed so as to straddle the expansion joint J formed on the concrete floor F, and the lower ground F1 of the concrete floor F. A non-adhesive region 4 that does not bond the lower ground F1 of the concrete floor and the back surface of the floor material 1 is provided between the back surface of the floor material 1 and the back surface of the floor material 1.

  The band 2 shown in FIG. 2 is a long trapezoid that is slanted so that the thickness decreases toward the outer edge 2a (the band 2 has an arc-shaped surface. In this way, by forming the outer edge 2a thin in this manner, the swelling of the surface of the flooring 1 caused by the thickness of the outer edge 2a is made inconspicuous. The band 2 may be adjusted to the length of the expansion joint J by cutting or adding on the construction site.

In the vicinity of the midpoint of the back surface of the band 2, a protrusion 2 b is provided over the entire length of the band 2 as shown in FIGS. 1 and 2. When the band 2 is placed on the expansion joint J, the protrusion 2b extends and contracts at an appropriate position because the protrusion 2b on the back of the band 2 fits into the expansion joint J and serves as a guide. The joint J can be covered with the band 2. Further, even when the pedestrian steps on the heel of the shoe, the ridges 2b are supported in contact with the joint seal material 5 of the expansion joint J, so that the flexure of the belt body 2 is reduced, and the floor material 1 on the part should be avoided. Even if pierced with a sharp object, the flooring 1 can be prevented from being damaged. Therefore, the lower end of the ridge 2b is formed to be rounded so as not to damage the joint sealing material 5 when contacting the joint sealing material 5 of the expansion joint J.
In addition, when the width dimension of this protruding item | line 2b is substantially equal to the width dimension of the expansion joint J, when the concrete floor F expand | swells and the width of the expansion joint J shrinks, the protruding item | line 2b becomes the expansion joint J. Since the problem of being pinched occurs, the width dimension is set in consideration of the expected expansion / contraction amount of the expansion joint J.

  Moreover, since the width dimension of the said strip | belt body 2 (width dimension of a back surface) is about 3-40 mm as the width | variety of the expansion-contraction joint J was mentioned above, what is necessary is just to form about 10-200 mm which can fully cover it. . The thickness (height from the back surface to the top surface) is preferably as thin as possible so that the swell of the surface of the flooring 1 is not conspicuous. It is appropriate to make it about 3 to 3 mm.

  The material of the band body 2 having the above structure has strength and rigidity enough to prevent bending or damage even when the band body 2 is stepped on with a heeled shoe, and has water resistance and rust resistance. It is not particularly limited as long as it is a metal, but an olefin resin such as vinyl chloride resin, polypropylene resin or polyethylene resin is suitable for a synthetic resin such as stainless steel, plated iron, or aluminum. Used. The band 2 can be formed by a known method. If it is made of metal, it is often formed by sheet metal pressing, bending, or extrusion. If it is made of synthetic resin, it can be formed by extrusion or injection molding. Often formed.

  In the floor material laying method of the present invention, the band 2 is placed so as to straddle the stretch joint J formed on the concrete floor F as shown in FIG. At this time, the protrusion 2b on the back surface of the band 2 is placed so as to be positioned in the middle of the expansion joint J. And as shown to (b) of FIG. 1, while applying the adhesive 3 for flooring to the surface of the lower ground F1 of the concrete floor F, and the strip | belt body 2, the lower floor F1 of a concrete floor, the flooring 1 back surface, A non-adhesive region 4 that does not adhere is provided.

  The flooring adhesive 3 for adhering and fixing the flooring 1 to the lower ground F1 of the concrete floor F is a curable adhesive that is mixed with a reaction initiator or started to react by moisture, and becomes hard after curing. Although a type is used, a flexible type may be used after curing. Typical adhesives include moisture curable one-component urethane adhesives, two-component mixed curable epoxy adhesives, moisture curable silicone adhesives, and the like.

  In the embodiment shown in FIGS. 1B and 1C, the non-adhesive region 4 is coated with the flooring adhesive 3 between the lower ground F <b> 1 of the concrete floor F and the back surface of the flooring 1. The non-adhesive region 4 is directed to the outside from the outer edges 2a and 2a on both sides of the belt 2 from the viewpoint of appropriately dividing and dispersing the stretching stress in two. 2 is provided over the entire length.

The width dimension of the non-adhesion area 4 (distance from the outer edge 2a of the band 2 to the adhesive 3) is preferably set to about 3 to 50 mm. If the width dimension of the non-adhesion area 4 is greater than 50 mm, The range where the swelling of the material 1 occurs becomes too large, and the swelling becomes conspicuous on the contrary. On the contrary, if the width dimension of the non-adhesive region 4 is smaller than 3 mm, it becomes difficult to appropriately disperse the stretching stress and the surface of the flooring 1 is likely to be whitened. The width dimension of the adhesion region 4 is preferably set to the above dimension.

  The means for providing the non-adhesive region 4 can also be provided by not applying the flooring adhesive 3 to the place where the non-adhesive region 4 is to be provided, but this is not so good in workability. Therefore, the masking tape is coated on the portion where the non-adhesive region 4 is to be provided, the flooring adhesive 3 is applied from above, and then the flooring adhesive 3 is removed by peeling the masking tape. A means for providing the non-adhesive region 4 is preferably performed.

  As described above, after providing the non-adhesive region 4, as shown in FIG. 1C, the flooring 1 is laid from above and bonded and fixed, whereby the laying of the flooring 1 is completed.

  In the method of laying the floor material as described above, since the synthetic resin floor material 1 is bonded and fixed to the lower ground F1 of the concrete floor F across the expansion joint J, the edge of the floor material 1 is cut, or the sealing material 7 This eliminates the need for a sealing process in order to improve workability and reduce costs. Moreover, since the expansion joint J is completely covered with the flooring 1, it is highly waterproof, and there is no fear that the heel of the pedestrian's shoes will fall and fall. Further, by placing the band 2 so as to straddle the expansion joint J, the expansion stress of the expansion joint J is divided into two parts on the outer edges 2a, 2a on both sides of the band 2, and in addition to that, the band Since the non-adhesive region 4 is provided on the outer side of the outer edge 2a of the floor 2, the stretching stress applied to the floor material 1 is dispersed throughout the non-adhesive region 4 without concentrating on a part of the floor material 1, and the floor material 1 The whitening phenomenon is less likely to occur on the surface, and the swelling is less noticeable. By providing this non-adhesive region 4, even if the joint width becomes narrow due to the expansion and contraction of the expansion joint J, the outer edge 2a of the belt body 2 smoothly slides on the ground surface F1, and the outer edge 2a of the belt body 2 is placed on the floor. Since the back surface of the material 1 is not damaged or pushed up, it can be suitably used for the concrete floor F having the expansion joint J which is assumed to have a thermal expansion and contraction of ± 0.1 to 3 mm.

  FIG. 4 is a cross-sectional view for explaining a flooring laying method according to another embodiment of the present invention.

Whereas the floor material laying method of the above-described embodiment provides the non-adhesive region 4 only from the outer edges 2a, 2a on both sides of the band 2 toward the outside, the floor material laying method according to this embodiment As shown in FIG. 4, the non-adhesive region 4 is not only on the outer sides of the outer edges 2 a and 2 a on both sides of the band 2 but between the back surface of the flooring 1 and the surface of the band 2, Are provided continuously toward the inner side of the outer edges 2a, 2a. In the non-adhesive region 4 of this embodiment, the distance from the outer edge 2a of the band 2 to the flooring adhesive 3 on the surface of the band 2 is preferably set to about 3 to 20 mm. If the entire surface is made into the non-adhesive region 4, the range of swelling of the flooring material 1 becomes too wide, and conversely the swelling of the flooring material 1 becomes conspicuous. 3 is preferably applied.
Since the other laying method of the flooring laying method according to this embodiment is the same as the laying method of the above-described embodiment, the same members are denoted by the same reference numerals and description thereof is omitted.

  Since the floor material laying method of this embodiment is provided with the non-adhesive region 4 between the inner side of the outer edge 2a of the belt body 2 and the back surface of the floor material 1, the range in which the stretching stress is dispersed increases. Further, the whitening phenomenon is less likely to occur on the surface of the flooring 1, and the swelling can be made inconspicuous.

  FIG. 5 is a cross-sectional view for explaining a flooring laying method according to still another embodiment of the present invention.

  The flooring laying method according to this embodiment is such that the adhesive tape 6 is attached to the locations (outer and inner sides of the outer edges 2a, 2a on both sides of the belt 2) where the non-adhesive region 4 of the embodiment shown in FIG. At the same time, after the adhesive tape 6 is adhered between the back surface of the band 2 and the lower ground F1 of the concrete floor F, the surface of the adhesive tape 6 adhered to the location where the non-adhesive region 4 is provided, the concrete floor F The flooring adhesive 1 is applied to the surface of the lower ground F1 and the belt body 2, and the flooring 1 is laid thereon.

When the floor material 1 is laid, the workability is not so good when the belt body 2 slides easily on the lower ground F1 of the concrete floor F, and the belt body 2 and the ground surface F1 are not good. If there is a gap between them, the band 2 and the base surface F1 may come into contact with each other and make a sound when walking on the gap. In addition, as shown in FIG. 5, the band 2 used in this embodiment is of a type in which the ridge 2 b is not provided on the back surface of the band 2. It is preferable to adhere and fix the lower ground F1 of the concrete floor F.
The term “adhesive fixation” as used herein means that the flooring 1 and the belt 2 can be slid with a certain degree of freedom and are continuously fixed in a state where they do not move easily even when a weak force is applied. This means different from the strong “adhesion fixation” by the flooring adhesive 3.

The pressure-sensitive adhesive tape 6 is obtained by providing a pressure-sensitive adhesive layer on a resin tape base material, and a tape having a thickness of about 0.1 to 3 mm and a width dimension of about 3 to 100 mm is preferably used. Although the tape base material which comprises the adhesive tape 6 is not necessarily an essential requirement, the adhesive tape 6 with a tape base material is preferable from the viewpoint of workability, and the material of the tape base material is paper, woven fabric, non-woven fabric, Known materials such as resin, foamed resin, rubber, metal foil, etc. are preferably used. Moreover, the material of the adhesive which comprises the adhesive tape 6 can apply well-known adhesives, such as an acrylic type, rubber type (especially butyl rubber type is optimal), urethane type, etc., and is water-resistant, aging-proof, and heat-resistant. Some are particularly preferred. By sticking such an adhesive tape 6 to the above-mentioned location, the flooring material 1 is firmly bonded and fixed to the lower ground F1 of the concrete floor F at the time of applying the flooring adhesive 3, and the air that has been caught is fixed. It is possible to prevent the belt body 2 from moving when the flooring 1 is pressed against the base surface F1 in order to remove it.
Since the other laying method of the flooring laying method according to this embodiment is the same as the laying method of the embodiment shown in FIG. 1 and FIG. 4 described above, the same members are denoted by the same reference numerals and description thereof is omitted. .

  The floor material laying method as described above prevents the adhesive tape 6 from coming into contact with the outside and inside of the outer edges 2a, 2a on both sides of the lower ground F1 and the strip 2 of the concrete floor F. The non-adhesive region 4 can be easily formed without adhering and fixing the portion that is not in contact with the flooring adhesive 3 and the back surface of the flooring 1.

  FIG. 6 is a cross-sectional view for explaining a flooring laying method according to still another embodiment of the present invention.

In this embodiment, as shown in FIG. 6, a band body 20 having different left and right outer edges 2 a and 2 a is used. In low-rise apartment corridors, precast concrete is often placed on a steel frame and fixed with bolts and nuts. In such a structure, since the precast concrete is not fixed to a strong ground, when the person walks, the precast concrete moves up and down, and a step may be generated on the left and right of the expansion joint J. The floor laying method of the embodiment shown in FIG. 1, FIG. 4, and FIG. 5 described above assumes that the concrete floor F expands and contracts to the left and right, but does not assume that there are steps on the top and bottom. The laying method of the present embodiment assumes the case where there are steps on the top and bottom. The belt body 20 used in this laying method has a surface that is gently inclined from one outer edge 2a toward the other outer edge 2a, and its back surface is cut in consideration of the thermal expansion and contraction of the concrete floor F. . When such a band 20 is used, even if there is a step between adjacent concrete floors F and F of the expansion joint J, it is possible to prevent the phenomenon that one side of the band 2 is lifted. By relaxing the steps on both sides to a gentle slope, it is possible to prevent whispering during walking.
As described above, the thickness adjustment on the left and right sides can be performed by making the heights of the outer edges 2a, 2a of the belt 20 different on the left and right sides as described above, but spacers are provided on the back surface of one outer edge 2a. It is also possible to carry out by providing inclusions such as affixing.
Since the other laying method of the flooring laying method according to this embodiment is the same as the laying method of the embodiment shown in FIG. 1, FIG. 4, and FIG. 6, the same members are denoted by the same reference numerals and described. Is omitted.

  When the flooring 1 is laid using the above-described flooring laying method, the flooring 1 is concreted across the expansion joint J even when there are steps on the left and right sides of the concrete floor F across the expansion joint J. It can be laid on the lower ground F1 of the floor F.

F Concrete floor F1 Lower ground J Stretch joint 1 Floor material 2,20 Strip 2a Outer edge 2b Projection 3 Floor adhesive 4 Non-adhesive area 5 Joint seal material 6 Adhesive tape 7 Sealing material

Claims (4)

A flooring laying method in which a synthetic resin flooring is laid on the lower ground of a concrete floor on which stretch joints are formed,
Place the band to straddle the expansion joint,
A non-adhesive region between the lower ground of the concrete floor and the back of the floor material, in contact with the outer edges of the both sides of the band and not bonding the lower floor of the concrete floor and the back of the floor over the entire length of the band Provided,
A method of laying a flooring material, characterized in that a synthetic resin flooring material is bonded and fixed to the ground surface of a concrete floor across the expansion joint.   2. The floor laying method according to claim 1, wherein the non-adhesion region is provided continuously between the inner side of the outer edge on both sides of the belt and the back surface of the floor material.   Adhesive tape is affixed to the location where the non-adhesive area is provided, and flooring adhesive that adheres and fixes the flooring to the ground floor of the concrete floor is applied to the ground floor of the concrete floor, the adhesive tape, and the belt. 3. The floor laying method according to claim 1, wherein the flooring is laid after the coating.   By using the flooring laying method according to any one of claims 1 to 3 on the lower ground of the concrete floor on which the stretch joints are formed, the synthetic resin floor material straddles the stretch joints. A floor structure characterized by being laid on the lower ground of a concrete floor.

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