GB2123056A

GB2123056A - Reinforced cement products

Info

Publication number: GB2123056A
Application number: GB08317482A
Authority: GB
Inventors: Kanetaka Nasu
Original assignee: TOEI SHOKO
Current assignee: TOEI SHOKO
Priority date: 1982-06-29
Filing date: 1983-06-28
Publication date: 1984-01-25
Also published as: FR2529240A1; DE3321771A1; GB8317482D0

Abstract

A cement product contains one or more frames (5) each frame comprising fiber 9 (e.g., glass fiber) wound about the frame with turns of the fiber extending substantially in parallel. If desired the fiber can be wound about the frame in two orthogonal directions or obliquely. Other frame shapes are described. <IMAGE>

Description

SPECIFICATION Cement products containing frame Background of the invention This invention relates to a cement product containing a frame.

Cement products containing glass fibers have been manufactured by direct spray method, spray suction method or premixing method.

Explaining the spray method, a cement paste or a slurry of mortar is supplied under pressure to a spray gun by a pump to be blasted against the surface of a frame through the spray gun. At the same time, a rope of glass fibres is cut by a chopper gun and chopped glass fibers are blasted against the frame surface together with the sprayed slurry. In this case, the glass fibers assume two dimensional random orientations.

Thus, spray method prepares a cement product containing thin sheet shaped glass fibers (GRC), whereas according to the direct spray method, the cement is cured to set while in the state of blasted against the frame surface. The latter method is now being used most widely because it can blast cement to a desired thickness against a frame having a complicated configuration.

The spray suction method utilizes a molding frame having a construction such that the pressure inside of the molding frame can be reduced, and the blasting is performed with a filter paper applied to the surface of the molding frame. After blasting, the pressure in the molding frame is reduced to remove surplus water through the filter paper. Then a sheet like product can be obtained having a certain degree of hardness that permits removal of the product from the molding frame. However, the product has a flexibility comparable with that of a soft rice cake so that by bending the product in this state, various products having different sectional configurations can be obtained.

However, the direct spray method and the spray suction method are defective in that the products must be sprayed independently which increases the cost of labor. Moreover, as the glass fibers are oriented two dimensionally and randomly, the efficiency of the fibers is lower than parallely oriented fibers.

In a premixing method, chopped strands of glass fibers are thoroughly admixed with cement mortar and then the mixture is cast in a molding frame. When the mixture is admixed with a conventional stirrer, the fibers tend to tangle, entangle or break. As a consequence, it is necessary to use a special stirrer capable of admixing the glass fibers in a short time.

Vibrations are applied to the mortar containing glass fibers and cast in the molding frame, but the control of the vibration time is difficult depending upon the shape and mass of the cast molding frame. The weight percent of the glass fibers with respect to mortar amounts to from 3 to 5%, so that the manufacturing cost is substantially high.

Further, the orientations of most of the glass fibers are two dimensional and random.

Such flat cement products as cement panels, usually comprise a concrete layer and a GRC layer which are molded together. This will be described with reference to Figs. 1 and 2 of the accompanying drawings. A portion 2 beneath a panel 1 is formed with a GRC which is prepared by either one of the premixing method and the spray method. After molding the lower portion 2, a reinforcing iron frame 3 shown in Fig. 2 is mounted thereon, and then a upper portion 4 is cast with ordinary concrete. The resulting structure becomes a flat plate comprising a GRC layer and an ordinary concrete layer.

The method described above is not advantageous in that it requires a number of steps and that a wide surface is finished by a smoothing iron, thus decreasing the productivity. Moreover, since the orientations of the glass fibers in the GRC portion are bidirectional and random, the fiber efficiency is low thus increasing the manufacturing cost. With any one of the prior art methods described above it has been difficult to orient glass fibers in a definite direction.

In another prior art method and a plurality of glass strands each consisting of a bundle of glass fibers bonded together by a resinous material are arranged in a matrix, and the cross points of the strands are bonded with strings. Accordingly, concrete can not enter into the glass strands at such cross points so that not only the bonding between the glass strands and the concrete is not sufficient but also such construction increases the manufacturing cost.

Summary of the invention Features of embodiments to be described are: concrete products containing a glass fiber frame capable of readily produced and having a high mechanical strength; a concrete product utilizing a glass fiber frame permitting casting of concrete into the frame even when the cast concrete is incorporated with relatively large aggregate; concrete products having various configurations utilizing glass fiber frames having configurations suitable for the resulting concrete products; and a cement product comprising a fiber frame including at least two frames embedded therein, and fibers bridged in parallel between said two frames.

The frame may take any desired form depending upon the construction and field of use of the concrete product. The fibers are preferably obtained by winding a long fiber about the two frames.

Brief description of the drawings In the accompanying drawings: Fig. 1 is a sectional view showing a prior art cement product; Fig. 2 is a perspective view showing a frame of reinforcing steel bars utilized in the product shown in Fig. 1: Fig. 3 is a perspective view showing a frame wound with a glass fiber according to this invention; Fig. 4 is a longitudinal sectional view of a concrete product embodying the invention; Fig. 5 is a longitudinal sectional view showing a modification of this invention; Fig. 6 is a perspective view showing a frame wound with glass fibers and utilized in the modification shown in Fig. 5; Fig. 7 is a perspective view showing a modified frame wound with glass fibers; Fig. 8 is a sectional view of a cement product utilizing the modified frame shown in Fig. 7;; Fig. 9 is a perspective view showing still another modification of a frame wound with glass fibers; Fig. 10 is a longitudinal sectional view of a cement product utilizing the frame shown in Fig.

9; Fig. 11 is a perspective view showing yet another modification of the frame with glass fibers; Fig. 12 a plan view showing a modified frame wound with glass fibers; Fig. 13 is a longitudinal sectional view of a concrete product utilizing the frame shown in Fig.

12; Figs. 14, 1 5 and 1 6 are perspective view, side view and front view respectively showing a further modification of a frame wound with glass fibers; Figs. 17, 18, 19 and 20 are plan views showing still other modifications of the frames wound with glass fibers; Fig. 21 is a longitudinal sectional view of concrete product utilizing the frames shown in Figs. 17-20; Fig. 22 is a perspective view, partly broken away, of a concrete product in which a frame is contained in the vertical direction; Fig. 23 is a plan view showing still another modification of the glass fiber frame; Fig. 24 is a perspective view showing a cubic glass fiber frame; Fig. 25 is a perspective view showing a glass fiber frame utilized to form a concrete duct; and Fig. 26 is a perspective view showing a glass fiber frame utilized to form a hollow concrete pipe.

Description of the preferred embodiments Fig. 3 shows one embodiment of a frame 5 wound with glass fibers (hereinafter called a glass fiber frame or a frame). As shown, the glass fiber frame 5 comprises a rectangular flat frame 8 made up of longitudinal steel bars 7 and lateral steel bars 6, and glass fibers 9 wound about the frame 8.

The glass fiber utilized in this invention may be a -straight continuous fiber, or a twisted continuous fiber or a bundle of glass fiber.

About opposing longitudinal sides 7a and 7b of the frame 8, is wound a continuous glass fiber 9 with a relatively short pitch. The glass fiber 9 is wound under a tension such that the respective turns would be perfectly or substantially parallel.

The glass fiber 9 wound about longitudinal sides 7a and 7b has a dynamic effect corresponding to the main steel bars. If lateral strength is required, another glass fiber is wound about lateral sides 6a and 6b at right angles with respect to the glass fiber 9 wound about the longitudinal sides 7a and 7b where the glass fiber frame is to be contained in a concrete product, the lower portion 2 thereof is prepared by casting ordinary concrete, and then applying vibration to cast concrete to make flat its surface. Then a glass fiber frame 5 is disposed on the surface of the cast concrete and the ordinary concrete is cast thereon to form the upper portion 4. Then vibration is applied to the cast concrete and its upper surface is smoothed with a smoothing iron to obtain a desired product 1 0.

Instead of casting concrete in two steps, it is possible to cast the concrete in one step when the glass fiber frame 5 is supported by a small supporting member in which case the supporting member is embedded in the concrete product 10.

Instead of the ordinary concrete, GRC may be used but this is not so effective.

Figs. 5 and 6 respectiveiy show a concrete product 11 in which the frame 5 shown in Fig. 3 is inserted and a modified glass fiber frame 5 is used. Usually, the minimum thickness of the concrete layer covering the reinforcing steel bars is 20 mm so that the thickness of the concrete layer shown in Fig. 1 would be 20 mm. However, since the purpose of utilizing GRC is to make thin the concrete layer, it is desirable to lower as far as possible the positions of the lateral rods 6. Then, the thickness of the concrete layer covering the lateral rods 6 will become 3 to 5 mm, but even with such small thickness, the glass fiber 9 can be sufficiently bonded.

The position and orientation of the glass fiber frame 5 can be selected to be most effective depending upon the configuration and dimension of the product.

Fig. 7 illustrates another embodiment of the glass fiber frame. As shown, the lateral rods 13 of the frame 12 take the form of a shallow letter V and are interconnected by four longitudinal rods 1 4a-1 4d to form a V shaped frame 15. A glass fiber 9 is wound about the frame 1 5 to complete the glass fiber frame 12. The glass fiber is wound at a constant pitch so that resulting turns are parallel with each other.

Fig. 8 shows a concrete.product utilizing the glass fiber frame 12 shown in Fig. 7.

The concrete product shown in Fig. 8 is different from that shown in Fig. 3 in that the transverse rods are V shaped instead bf straight, that the distance between the upper side and the lower side of the wound glass fiber is larger than that shown in Fig. 3 and that concrete is filled between the upper and lower side. Where the concrete panel is thin, it must have a large shear strength. From this standpoint the embodiment shown in Figs. 7 and 8 is more efficient. The concrete product 1 6 shown in Fig. 8 and containing the glass fiber frame 1 2 shown in Fig.

7 has a bending strength higher by 4060% than a concrete product containing a frame constituted by V shaped reinforcing steel rod and not wound with a glass fiber.

Fig. 9 shows still another modification of the glass fiber frame 1 7 in which both ends of each transverse rod 1 8 are bent upwardly and the transverse rods 1 8 are interconnected by five longitudinal rods 1 9 to form a frustum shaped frame 20. A glass fiber 9 is densely wound around the frame 20 to obtain a glass fiber frame 17. Fig.

1 0 shows a concrete product 21 utilizing the glass fiber frame 17 shown in Fig. 9. This product can be manufactured substantially in the same manner as the product 10 shown in Fig. 4.

Fig. 11 shows still another modification of the glass fiber frame 22 comprising an elongated cubic frame 23 and a glass fiber 9 wound about it.

Fig. 12 shows another embodiment of the glass fiber frame 24 which is substantially identical to that shown in Fig. 3 except that, successive turns are separated by spacings t.

Such spacings prevent discontinuous casting of concrete due to the glass fiber frame 24. The width of the spacing t is determined by the size of the aggregate incorporated into concrete, a suitable width amounting to 20-50 mm. In the glass fiber frame 5 shown in Fig. 3, it is supposed that the pitch of the wound glass fiber is 3 mm.

When the glass fiber frame 5 shown in Fig. 3 is used the cast concrete or mortar may be discontinuous at the glass fiber frame so as to be separated into upper and lower layers. The purpose of the spacings t is to interconnect the upper and lower layers into an integral rigid structure. It will be clear that the spacing t may also be provided for other types of the glass fiber frames. Fig. 13 shows a concrete product 25 utilizing the glass fiber frame 24 shown in Fig. 12.

Although in the embodiment shown in Fig. 12, respective turns of the wound glass fiber was separated by spacings t, it will be clear that the glass fiber may be wound with a small spacing and then with a large spacing. With this construction, even when the cast concrete contains aggregates having a size of 20-40 mm, the upper and lower layers of the cast concrete would be strongly bonded.

Figs. 14, 1 5 and 16 show still further modification of the glass fiber frame 26 comprising a flat frame bounded by sides 27a27d, a frame 29 constituted by vertical projectoins 28a and 28b secured to the sides 27a and 27b at a definite spacing, and a glass fiber 9 wound under a tension about the frame 29 as shown in Figs. 1 5 and 1 6. According to this modification, since several vertical walls perpendicular to the plane bounded by sides 27a-27d are provided, the mechanical strength of the cast concrete product can be increased.

When applied with an external force of a given magnitude from above the concrete product shown in Fig. 1 6 has much larger resistance than those shown in Figs. 3 and 6 because the plate shaped walls comprising glass fibers wound about vertical rods 28a and 28b provide large mechanical strength.

Figs. 1 7-20 show still other modifications of the glass fiber frames according to this invention.

In the embodiment shown in Fig. 17, the turns of the glass fiber 9 are parallel with lateral rods 30, whereas in the embodiment shown in Fig. 18 the turns are parallel with the longitudinal rods 31. In the embodiment shown in Fig. 19, the turns of the glass wire 9 are parallel with one diagonal whereas in the embodiment shown in Fig. 20 the turns are parallel with the other diagonal. In Figs.

17-20, reference numerals 32-35 show glass fiber frames.

If desired constructions shown in Figs. 1 9-20 may be combined. In other words, glass fibers may be wound about a single frame such that turns extending in opposite directions cross each other.

Fig. 21 is a sectional view showing a concrete product 36 containing a number of glass fiber frames 32-35 superposed in the order mentioned with predetermined spacings therebetween. This product has a strength against shock.

In any of the foregoing embodiments, the glass fiber frame may be embedded in the concrete product in the horizontal or vertical direction. The manner of embedding the glass fiber frame 5 shown in Fig. 3 has already been described in connection with Fig. 5, and the manner of embedding the glass fiber frame in the vertical direction is shown in Fig. 22.

When embedding the glass fiber frame in the horizontal direction, a glass fiber frame is disposed in a casting frame, not shown, and the bottom of the glass fiber frame is supported a short distance above the bottom of the casting frame by suitable spacers, not shown. Thereafter concrete is cast from above into the casting frame and then the casting frame is subjected to vibrations. The horizontal embedding and the vertical embedding are different in the following points. The vertical embedding has a higher productivity. The quantity of concrete or mortar poured into the space between glass fibers are different for the vertical and horizontal embeddings. More particularly, in the case of the horizontal embedding, the quantity of mortar or concrete cast into the space of the glass fibers is small.In the case of the vertical embedding shown in Fig. 22, the mortar or concrete not only adheres to the surface of the glass fibers but also enters into a space between glass fibers.

Moreover, the cast motar or concrete readily flows down along the glass fibers and hence increases the density of the cast product as well as the quantity of the concrete in the space between glass fibers. This means that the fiber efficiency is higher in the vertical embedding than in the horizontal embedding. Furthermore, the surface finish is smoother in the vertical embedding than in the horizontal embedding. The vertical embedding is useful for manufacturing elongated concrete products having square or rectangular cross section.

As far as the inventor is aware, parallel orientation of glass fibers in the vertical embedding is novel. Since the orientation of the glass fiber is determined when it is wound about the frame, difficulties encountered at the time of casting concrete can be obviated beforehand by winding the glass fiber by taking into consideration the size of the aggregate as well as the casting condition.

In the glass fiber frame, it is essential to wind the glass fiber under tension about the frame, and the frame itself should have substantial mechanical strength which is determined by such factors as external force applied to concrete products, the sizes and dimensions thereof.

A steel rod may be substituted by soft iron or steel wire. Furthermore, instead of rod or wire having circular sectional configuration, such reinforcing members having different sectional configuration as angle members circular or angular pipes, and members having semicircular configurations can be used. Further, the material of the frame is not limited to steel or iron, but plastics, aluminum, piano wire wood, etc. can also be used so long as the glass fiber can be wound under tension about the frame.

Although it is advantageous to use a long glass fiber, other fibers, for example carbon fibers, nylon fibers, steel fibers can be used so long as they can be wound under tension. Instead of a single fiber a plurality of fibers may be wound simultaneously with or without bonding them into a strand with synthetic resin so as to improve the winding efficiency.

Furthermore, instead of winding a single long fiber about a frame, both ends of a plurality of sections of the fiber may be fastened to opposing sides of the frame. However this method is not advantageous because of its low workability. A plurality of hooks may be formed on the opposing inner sides of the frame so as to successively engage a continuous fiber under tension.

Alternatively, spaced openings may be formed through opposing sides of a frame to successively thread a continuous fiber through the openings.

Further, a wire net of fibers may be preformed for securing the ends to the sides of the frame. In this case the four sides of the wire net may be clamped between two superposed frames.

As above described, a frame of a desired configuration is provided with a plurality of spaced parallel fibers under tension and the frame is then cast in concrete or mortar, so that the resulting cast product has a high mechanical strength.

According to a still further modification shown in Fig. 23, the glass fiber frame 55 comprises a flat rectangular frame 56 made of a metal wire 56, for example, and glass fibers 57 wound about the frame 56 in the horizontal and vertical directions. Since the glass fibers 57 are wound under tension, one or more reinforcing members may be provided. One or a plurality of spaced apart glass fiber frames may be embedded in a cast concrete product in the horizontal or vertical direciton to obtain a hollow rectangular product.

In a modification shown in Fig. 24 the frame 70 takes the form of a cube and glass fibers 71 and 72 are wound about the frame 70 in the vertical and horizontal directions. As before, one or more glass fiber frames 70 shown in Fig. 24 may be embedded in a cast concrete product in the horizontal or vertical direction to obtain a hollow rectangular product.

If desired, the glass fiber frame may be constructed to have a U shaped cross-sectional configuration in which glass fibers are wound about the frame in the horizontal and vertical directions except the upper side of the frame as shown in Fig. 25. Such glass fiber frame is suitable to form concrete ducts having U shaped cross-sectional configuration.

According to the configuration of the concrete product the glass fiber frame may have a hollow square or circular form, as shown in Fig. 26 or an L shape. Where the frame shown in Fig. 26 is used a hollow concrete pipe can be obtained. In the modifications shown in Figs. 24, 25 and 26, where the concrete products have a large thickness glass fiber frames having different sizes may be combined to increase the strength of the products.

Claims

1. A cement product including a frame embedded therein and fibers arranged substantially in parallel upon the frame.

2. A cement product as claimed in claim 1 in which the said fibers are tensioned.

3. A cement product as claimed in claim 1 in which the frame includes a plurality of spaced longitudinal rods and a plurality of lateral rods, the longitudinal and the lateral rods being connected together to form a grid, and the parallel fiber arrangement being obtained by winding a fiber under tension about the frame to form substantially parallel turns of the fiber.

4. A concrete product as claimed in any one of the preceding claims in which the frame is rectangular and has an intermediate reinforcing member.

5. A concrete product as claimed in either claim 1 or claim 2 in which the frame is rectangular and the parallel arrangement of the fibers is obtained by winding a fiber obliquely about the frame.

6. A concrete product as claimed in either claim 1 or claim 2 in which the frame is rectangular and two orthogonal arrangements, each of parallel fibers, is provided by winding a fiber about the frame.

7. A concrete product as claimed in claim 6 in which the frame has a hollow cubic configuration.

8. A concrete product as claimed in any one of the precediing claims in which the frame includes an elongated member having a U-shape, thereby providing the frame with a U-shaped sectional configuration.

9. A concrete product as claimed in any one of claims 1-6 in which the frame includes a hollow cylindrical member having a rectangular or a square cross-sectional configuration.

10. A concrete product as claimed in claim 1 in which the frame includes a hollow cylindrical member.

11. A concrete product as claimed in claim 1, substantially as described herein with reference to Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig.

12, Fig.

13, Figs. 14-16, Fig. 17, Fig. 18, Fig. 19, Fig. 20, Fig. 21, Fig. 22, Fig. 23, Fig. 24, Fig. 25, any one of Figs. 3-13, Figs. 14-1 6, or any one of Figs. 17-25.