JPH07100357B2 - Fiber reinforced cement mortar molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a fiber-reinforced cement mortar molded product obtained by orienting and embedding a reticulated body composed of long fibers in a cement mortar matrix.

<Prior Art> Generally, a fiber-reinforced cement mortar molded product is widely used as a member for civil engineering / construction in a shape of a plate, a cylinder, a hollow plate, a block, or the like.

So-called asbestos slate has been a typical example of a fiber-reinforced cement mortar molding, but recently, various organic and inorganic fibers have come to be used from the viewpoint of environmental pollution and prevention by asbestos.

<Problems to be Solved by the Invention> However, most of these are produced by a method in which short fibers are two-dimensionally or three-dimensionally randomly dispersed in cement mortar. It requires a large amount of fiber and is wasteful.

In particular, when high-performance fibers are used, there is a drawback that the strength and elasticity of the fibers cannot be sufficiently drawn out and the cost tends to increase.

For this reason, there has been considered a method of improving the physical properties of the mortar molded product by preliminarily molding the long fibers into a linear or lattice shape and predominantly orienting one-dimensionally or two-dimensionally in the cement mortar matrix section.

According to this method, compared with a molded product having two-dimensional or three-dimensional random orientation, a small amount of fiber is required to obtain the same bending or tensile strength, and the material can be designed. It has the advantage that it can be used effectively.

However, the conventional reinforcing method using long fibers has a drawback that the adhesive force between the cement mortar matrix and the reinforcing fibers or the adhesive force between the fibers is insufficient and pull-out easily occurs, and sufficient strength cannot be extracted. .

On the other hand, if the fiber bundle is impregnated with resin to form a rod, high strength can be expected as a fiber reinforced resin body, but these are crossed,
There is a problem that each rod is pulled out from the cement mortar matrix when loaded by simply making the grid and bonding the contacts.

On the other hand, the adhesive force between the cement mortar matrix and the fiber can be improved by making the surface of the fiber uneven or making it into a fibril (beard root), but the higher the strength of the fiber becomes, the more the fiber fractures rapidly. It has a drawback that it is poor in tenacity as a reinforcing material, that is, toughness.

In addition, in order to increase the toughness of the molded product, measures such as increasing the elongation of the fiber, adjusting the adhesion strength between the fiber and the cement mortar matrix, and crushing the cement mortar matrix on the compression side have been made. However, there is a problem in that the cross-sectional design of the molded product is difficult and the quality is not stable.

<Means for Solving Problems> Therefore, the inventors of the present invention have made diligent studies in view of the above problems, and as a result, in the case of a mesh body previously entangled and woven, the entangled fibers forming the mesh body have a bending moment. It has been found that these problems can be solved by embedding in cement mortar so as to be arranged in the direction of the tensile stress caused thereby, and arrived at the present invention.

That is, an object of the present invention is to provide a fiber-reinforced cement mortar molded article which is excellent in stress transmission to cement mortar matrix and has high strength, high toughness and impact resistance only by using a small amount of long fibers. Especially.

And, the purpose is a cement mortar molded body reinforced with a fiber mesh, the mesh is composed of entangled weave, and the resin impregnation treatment is performed, and the maximum generated by a bending moment. This is easily achieved by a fiber-reinforced cement mortar compact characterized in that it is embedded in cement mortar so that the entangled fibers constituting the reticulate body are arranged in the direction of tensile stress.

Hereinafter, the present invention will be described in detail.

The cement mortar used in the present invention is not particularly limited as long as it is a normal Portland cement, an early-strength Portland cement, or a cement having a hydraulic property as used in the usual production of cement products.

The reinforcing fiber may be made of any organic or inorganic material, but especially carbon fiber, alkali-resistant glass fiber, aramid fiber, high-strength vinylon fiber, etc. having a single-system strength of 150 kgf / mm ² or more and alkali resistance. Is particularly preferable.

In the present invention, a net-like body in which reinforcing fibers are entwined and woven is used. FIG. 1 shows an example of the shape.

In FIG. 1, 1 is a entangled weave fiber and 2 is a weft fiber. In this example, since one type of fiber bundle is used, the number of fibers of 1 is twice the number of fibers of 2. However, the number of fibers in the vertical and horizontal directions is arbitrarily determined according to the design conditions of the molded body. be able to.

Further, the materials and types of the longitudinal fibers and the transverse fibers are appropriately selected and determined. The mesh size of the mesh is arbitrary as long as it does not prevent the continuity of the cement mortar matrix, but it is usually 10 squares.
/ inch or less (2.5 mm @ or more), preferably 5 squares / i
It is practical to set the range from nch (5mm @) to 2 square inches (12.7mm @).

In the present invention, a resin impregnation treatment is performed on these reticulate bodies, but such treatment can be carried out by a conventional method.
For example, it may be dipped in a resin bath or may be impregnated with a roller.

Further, after impregnation with the resin, it is preferable to perform suspension drying for a certain period of time.

A non-water-soluble resin is suitable as the resin with which the entangled and woven net-like body is impregnated.

In particular, resin that can be easily impregnated into fiber aggregates, is easy to install, has low viscosity, and is curable at room temperature is suitable, but these resins do not deteriorate with age in the alkaline environment in cement mortar. preferable.

Specifically, it is preferable to use an epoxy resin, a urethane resin, a phenol resin, or the like.

Note that, particularly when the entangled and woven mesh body is required to have repellency, SBR latex having a high degree of polymerization may be used.

Further, an uncured epoxy resin having a softening point of 40 ° C. or higher may be used.

After the resin is impregnated into the entangled woven mesh and the resin is cured, the entangled woven fibers are arranged in the cement mortar in the direction of the maximum tensile stress caused by the bending moment.

That is, as shown in FIGS. 2 and 3, the entangled woven fibers 1 of the mesh body 4 are oriented in the longitudinal direction of the cement mortar sample 3, that is, in the direction of the maximum tensile stress generated by the bending moment.

In this example, one layer of the net-like material is contained only at the lower end of the mortar sample 3, but a plurality of layers may be laminated depending on the cross-sectional design conditions, or may be laminated on the upper end of the sample.

At this time, the resin does not necessarily have to be hardened, but it is preferable to harden the resin because the resin can be easily applied and laminated and damage to the fiber can be prevented during handling.

In order to further improve the adhesion with the matrix, fine sand or the like may be again adhered to the surface of the net with a resin after impregnating and curing the resin to give an anchoring effect to the matrix.

Here, the fiber-reinforced resin rods (FRP rods) that have been entangled and woven are resin-impregnated and cured, then cut out without being laminated with mortar, and simply twisted and woven and twisted into two fibers (FRP rods).
When the tensile strength is measured in the form of, the strength is only slightly higher than the strength of one FRP rod linearly impregnated with resin, so the reinforcing effect can hardly be expected.

However, when the entangled woven mesh body is laminated on the mortar as in the present invention, the entanglement with the weft yarn improves the adhesive force with the matrix, and the strength close to that of two linear FRP rods is developed. Because the weft thread is pulled in,
At the same time, the toughness is significantly improved.

The embedding of these fibrous nets in the mortar may be carried out by a conventional method.

For example, a conventional stacking / embedding method may be used, or after three-dimensionally incorporating in a mold, mortar may be injected and cured.

At this time, if defoaming is performed by vibrating with a vibrator or the like, the adhesion between the mortar matrix and the reinforcing fiber assembly becomes even tighter, and good mechanical properties can be obtained.

According to this method, a cross-section designing method similar to that of a normal rebar concorte can be applied, and efficient reinforcement can be achieved with a small amount of long fibers.

Further, in the present invention, it is preferable that short fibers are contained in the mortar when the network of entangled woven fibers made of long fibers is embedded in the mortar. That is, when the short fiber-containing mortar is used, as shown in FIG. 5, compared with the case where only the entangled woven net body is laminated, a molded product having a high level of bending stress is obtained in the entire area of the amount of deflection. be able to. FIG. 5 is a bending stress-strain curve of each specimen, which is 7 in the figure.
4 is a specimen in which the same entangled woven mesh as shown in FIG. 4 is embedded in cement mortar, 8 is a specimen in which short fibers are mixed with mortar by the direct spray method, 9 is the same entanglement as used in specimen 7. This is a specimen in which a mortar in which short fibers are mixed by a direct spray method is injected into a woven net.

The type of short fibers to be mixed with the mortar is not particularly limited, and any of the same type or different types of entangled woven fibers can be used, but carbon fiber, alkali resistant glass fiber, aramid fiber, high strength vinylon fiber, etc. are particularly preferable. Used. These short fibers usually have a length of about 1 to 50 mm and are mixed with a mortar according to a well-known method such as a direct spray method or a premix method. The mixing amount with mortar is 0.2 per 100 parts by volume of mortar.
It is selected from the range of up to 10 parts by volume.

<Examples> Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 A high-strength carbon fiber (“TOA Bethron's“ HTA-7-3000 ”, no twist) entwined and woven mesh (3.5 mass / inch) was diluted with a solvent (toluene: isopropyl alcohol = 4: 1 weight ratio) at room temperature. It was impregnated with a curable epoxy resin (manufactured by Dainippon Color Materials, main agent "B-910R", curing agent: "B-910H") and air dried.

This net has a basis weight of about 95 g / m ² , and each carbon fiber aggregate has 6000 filaments in the weaving direction and 3000 filaments in the transverse direction.

W: 40 × t: 20 × 1: 320m by embedding this mesh-like body in a cement mortar so that the fibers are entangled and the fiber direction becomes the longitudinal direction.
A bending specimen of m was prepared.

The fiber volume content in the cross-sectional direction was 0.17%, and the fiber network was arranged at a position 2 to 3 mm from the lower end of the mortar sample.

The cement was early-strength Portland cement, the fine aggregate was Toyoura standard sand, the water cement ratio was 0.55, and the fine aggregate ratio was 1.6.

Bending strength is obtained by subjecting the specimen after curing for 1 week to a center single point bending test with a span of 260 mm.

The number of specimens is n = 3.

The bending strength was 160.4 kg / cm ^{2 on} average, the deformation proceeded even after the maximum bending stress was reached, and the deflection at the central part exceeded 10 mm.

Bending cracks occurred in two to three places from the center to the left and right, but the specimen did not break and fell from the supporting end.

Example 2 In place of the cement mortar in Example 1, high-strength Portland cement was used, and silica sand No. 5 was used as a fine aggregate in an aggregate ratio of 0.
66, a mixture of water and water cement ratio of 0.32, carbon fiber (tensile strength 180kg / mm ² , tensile elastic modulus 16t / mm ² , yarn diameter 15
[mu]) was cut into 1.8 cm by the direct spray method, and a sample was obtained in the same manner as in Example 1 except that 1% by volume mixture was used.

A bending test was performed on the obtained specimen in the same manner as in Example 1. The test results obtained are shown as curve 9 in FIG.

Comparative Example 1 The volume content of the weft yarn in the mortar cross-sectional area was set to 0.15%, which is the same as that of the above example, except that the weft yarn was oriented in the longitudinal direction and the entangled fiber direction was oriented in the transverse direction. A cement mortar specimen was prepared.

When this sample was subjected to the same bending test, the bending strength was 18
Although it was 6 kg / cm ² , the fiber broke as soon as the maximum bending stress was reached, and the test piece was broken into two pieces and dropped from the supporting end.

The maximum amount of deflection at this time was 4.5 mm, which was less than half of the value in the above-mentioned embodiment.

Comparative Example 2 A short fiber-containing mortar specimen was prepared by the direct spray method in exactly the same manner as in Example 2 except that the entangled and woven net in Example 2 was not provided. A bending test was conducted in the same manner. The test results obtained are shown as curve 8 in FIG.

For reference, a sample prepared in exactly the same manner as in Example 2 except that a mortar containing no short fibers (the composition is the same as in Example 2) was used in place of the mortar containing short fibers in Example 2. The bending test result of the sample is shown as curve 7 in FIG.

<Effects of the Invention> According to the present invention, it is possible to obtain a cement mortar compact having good adhesion between the reinforcing fiber and the cement mortar matrix and having a small amount of fiber and excellent bending toughness and strength.

Further, like the reinforced concrete structure, it is possible to effectively and easily design the cross-section according to the application and load conditions.

When a molded product using carbon fiber as the reinforcing fiber is used in contact with a metal, or when a metal reinforcing material such as a reinforcing bar is arranged in the molded product, the carbon fiber is coated with a resin so that the carbon fiber is There is also an advantage in that the metal and the metal are electrically insulated from each other, and electrolytic corrosion of the metal is prevented.

[Brief description of drawings]

FIG. 1 is a plan view of the entwined woven mesh body, FIG. 2 is a sketch of a mortar specimen in which entangled woven mesh bodies are laminated (entangled woven fibers are oriented in the longitudinal direction of the swatch), and FIG. 3 is entangled woven fiber. FIG. 4 is a bending stress-strain curve (span: 260 mm) of the entangled woven mesh laminated mortar, and FIG. 5 is a bending stress-strain curve of each mortar sample. . 1: Entangled woven fiber 2: Weft fiber 3: Cement mortar 4: Entangled woven fiber mesh 5,7: Cement mortar sample (entangled woven fiber is oriented and laminated in the longitudinal direction) 6: Cement mortar sample (weft 8: Cement mortar specimen (spraying mortar containing short fibers by direct spray method) 9: Cement mortar specimen (entangled woven fibers oriented and laminated in the specimen longitudinal direction) Then, mortar containing short fibers is injected into this by the direct spray method)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirofumi Ota 1 2447, Fujita, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture Mitsubishi Kasei Kogyo Co., Ltd. Kurosaki Plant (56) Bibliography 54-143872 )

Claims (2)

[Claims] 1. A cement mortar molded body reinforced with a fiber mesh body, wherein the mesh body is composed of entwined weave, is resin-impregnated, and has a maximum bending moment. A fiber-reinforced cement mortar molded article, which is embedded in cement mortar so that the entangled fibers forming the reticulate body are arranged in the direction of tensile stress. 2. The molded product according to claim 1, wherein the cement mortar contains short fibers.