JP7219147B2 - cement reinforcement - Google Patents

Description

The present invention relates to a cement reinforcing material for use in mortar and concrete.

Mortar or concrete moldings are used in large quantities in the fields of construction and civil engineering because they are inexpensive while exhibiting excellent properties such as compressive strength, durability, and noncombustibility. However, these moldings are brittle materials, and are easily cracked or broken when stress such as tension, bending, or bending is applied.

In order to compensate for this drawback, organic polymer fibers are used to reinforce mortar and concrete moldings. This reinforcement can improve mechanical properties such as bending strength and bending toughness of the molding.

However, even when organic polymer fibers are used in the form of short fibers, the reinforcing effect is insufficient, and when long fibers are used, dispersibility in mortar and concrete decreases. It is a problem that the fibers are entangled with each other.

In order to obtain sufficient dispersibility, it is conceivable to use monofilament short fibers with a large fiber diameter, but the strength per fiber thickness is reduced, so the reinforcing effect cannot be sufficiently exhibited.

In order to solve this problem, in Patent Document 1, a method of bundling fibers (multifilament) consisting of a large number of fine filaments with a resin and attaching non-volatile oil to the bundled fibers to increase the bundling property of the fibers. is disclosed. However, although this method can increase the bundling property of the fibers, the adhesive force at the interface between the fibers and mortar or concrete is insufficient, and a sufficient reinforcing effect cannot be obtained.

JP 2007-131464 A JP 2012-25603 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a cement reinforcing material that has high fiber coherence and excellent reinforcing effect, and in particular, to provide a cement reinforcing material that has an excellent reinforcing effect for highly viscous mortar or concrete.

That is, the present invention is a cement reinforcing material comprising a fibrous material and a resin material covering the fibrous material, wherein the fibrous material is a spun yarn or stretch-broken yarn.
The invention also includes moldings of mortar or concrete containing the cement reinforcements described above.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide a cement reinforcing material having high fiber bundle property and excellent reinforcing effect, in particular, a cement reinforcing material having excellent reinforcing effect for highly viscous mortar or concrete.

The present invention will be described in detail below.

<Textile material>
Fibers used for the fiber material are preferably fibers having excellent alkali resistance, such as carbon fibers, glass fibers, steel fibers, ceramic fibers, inorganic fibers such as asbestos fibers, aramid fibers, vinylon fibers, polypropylene fibers, and polyethylene fibers. , polyarylate fiber, polybenzoxazole (PBO) fiber, nylon fiber, polyester fiber, acrylic fiber, vinyl chloride fiber, polyketone fiber, cellulose fiber, and pulp fiber. These may be used singly or in combination of two or more.

Among them, para-aramid, especially polyparaphenylene terephthalamide and copolyparaphenylene/3,4'oxydiphenylene/terephthalamide fibers are preferable because they have a large reinforcing effect. Terephthalamide fibers show little deterioration in mechanical properties even when kept for a long time in a strong alkaline atmosphere at ^high temperature and pressure. It is preferable because it has a high strength retention even in curing.

The total fineness of the fibrous material is preferably 90-1150 dtex, more preferably 180-575 dtex. If it is less than 90 dtex, the dispersibility in mortar or concrete is lowered, and the fibers may become entangled with each other, which is not preferable. It is not preferable because it is easy to use and it is difficult to obtain a high reinforcing effect.

The fineness of the single fibers of the spun yarn and stretch-breaking yarn of the fiber material is preferably 0.5 to 30 dtex, more preferably 0.6 to 20 dtex, and particularly preferably 0.7 to 10 dtex. If the fineness of the single fibers is less than 0.5 dtex, it becomes difficult to arrange the single fibers, and if the arrangement is insufficient, the mechanical performance cannot be fully utilized. In addition, uneven adhesion of the resin material is likely to occur between the single fibers, and a predetermined bundling property may not be obtained. On the other hand, if the fineness of the single fibers exceeds 30 dtex, the bonding area between the single fibers becomes small, making it difficult to maintain the bundling by the resin material.

In the present invention, a spun yarn or stretch-broken yarn in which short fibers are partially entangled to form a continuous yarn (single yarn) is used, preferably a stretch-broken yarn. To efficiently form a resin material layer having unevenness on the surface of a fiber material by using a spun yarn or a stretch-break processed yarn, which has many fluffs on the surface thereof, so that a large surface area can be obtained. can be done. The layer of the resin material having the unevenness can enhance the adhesion and bonding strength with cement due to the anchor effect, and can improve the reinforcing performance. In particular, stretch-breaking yarn is preferable because it has many fluffs on its surface and has excellent mechanical properties of the fiber.

The spun yarn may be further twisted after the spinning process. The spun yarn and stretch-break processed yarn may be used as a single yarn as a fiber material, or may be used as a fiber material by bundling a plurality of single yarns. When using a plurality of single yarns, for example, 2 to 8, preferably 2 to 4 single yarns are used. In this case, it is preferable that two or more single yarns are aligned or twisted together before being used as the fiber material.

The fibrous material may be further twisted in the same direction or in the opposite direction to the twist direction applied in the manufacturing process of the spun yarn or stretch-break yarn. When a plied material obtained by twisting a plurality of single yarns in the opposite direction to the twisting direction applied in the manufacturing process of spun yarn or stretch-broken yarn is used as a fiber material, many irregularities are created on the surface of the fiber material. When the cement reinforcing material of the present invention is mixed with mortar or concrete and hardened, the mortar or concrete penetrates into the irregularities on the surface of the cement reinforcing material bundled with plied twists and the adhesive strength is improved, which is preferable. Furthermore, the adhesive force at the interface between the fiber material and the resin material also increases as the unevenness of the surface of the fiber material increases, thereby improving the reinforcing performance.

A spun yarn can be produced by a known method. The twist coefficient K of the spun yarn is preferably 2.5 to 4.5 from the viewpoint of obtaining good tensile strength. where T=K√n, where T is the number of twists per inch (2.54 cm), n is the British cotton count, and K is the twist factor.

The stretch-breaking yarn can be produced by a known method. For example, a continuous long fiber bundle is stretched between nip rollers to a breaking elongation of the continuous long fiber bundle or more, and then the stretch-broken fibers are stretched from the nip rollers. It is sucked and pulled by a suction air nozzle, then entangled with each other and/or bound by winding the ends of the stretch-cut fibers with a binding air nozzle, and stretch-breaking is a continuous single yarn through nip rollers. It can be obtained by a method of winding as a thread. Bonding of the stretch-broken fibers by the tying air nozzle may be performed by winding the ends of the fibers with an interlaced air nozzle or a swirling air nozzle. The stretch-breaking yarn may be twisted with a single twist or may be twisted with a ply twist.

If the fiber length of the short fibers that make up the single yarn of the stretch-breaking yarn is long, the fiber arrangement degree is higher than that of the spun yarn, so that high strength can be obtained. From this point of view, it is preferable that the single yarn of the continuous fiber used as the raw material for the single yarn of the stretch-broken yarn is stretch-broken under the condition that the average fiber length is 10 to 150 cm.

The tensile strength of the fibrous material is preferably 7 cN/dtex or more, more preferably 10-40 cN/dtex. If the tensile strength is lower than this, the bending strength of the mortar or concrete molding will be low.

<Resin material>
In the present invention, the resin material that coats the fiber material should be a resin that easily permeates into the fiber bundle of the fiber material, easily bonds single fibers to each other in the fiber bundle of the fiber material, and has high tenacity. is preferable, and from this point of view, a resin containing an isocyanate compound as a constituent component is preferable. Specific examples include isocyanate resins, polyurethane resins, and crosslinked products of isocyanate and epoxy.

The isocyanate compound is selected from aromatic diphenylmethane diisocyanate, toluene diisocyanate, and aliphatic hexamethylene diisocyanate. Aliphatic isocyanate is preferred because of its excellent permeability into the fiber bundle. Blocked isocyanates are particularly preferred. Furthermore, it is preferable to use an epoxy compound together.

The amount of the resin material that coats the fibrous material is preferably 3 to 20% by weight, more preferably 8 to 20% by weight, per 100% by weight of the fibrous material. If the adhered amount is less than this, the bundle of the fibrous material is loosened and the single fibers are separated, which tends to impair the fluidity of the material. This is because when the fiber material is kneaded with mortar or concrete and a shearing force is applied to the fiber material, the fiber material cannot be kept bundled by the resin material. On the other hand, if the applied amount is larger than this, the strength of the fiber tends not to be fully utilized. If the adhesion amount is excessively increased, the convergence itself does not improve so much. Further, when the amount of the resin material attached increases, the apparent fineness of the cement reinforcing material of the present invention increases, and the tensile strength per unit weight of the bundled fibers decreases.

The resin such as the isocyanate compound mentioned above contributes to the bundling of the fibers. The surface of the cement reinforcing material of the present invention may be further coated with other resins for the purpose of improving adhesion to mortar or concrete.

In the cement reinforcing material of the present invention, in addition to the resin material described above, it is preferable that an epoxy resin having an epoxy group as a constituent component is present on the surface of the fiber material. It is preferable that a resin or a bisphenol A type epoxy resin, particularly an acrylic-modified bisphenol A type epoxy resin, exists on the surface of the fiber material. In this case, high performance is exhibited. When the epoxy resin is present on the surface, the adhesion amount is, for example, 0.1 to 10% by weight with respect to 100% by weight of the fiber material.

<Cement reinforcing material>
From the viewpoint of the reinforcing effect, particularly from the viewpoint of crack suppression, high bending strength and high bending toughness, the cement reinforcing material of the present invention preferably has a diameter of 0.05 to 0.5 mm, more preferably 0.1 to 0.1 mm. 0.4 mm. The cement reinforcement is preferably in the form of short fibers and preferably has a length of 5 to 25 mm, more preferably 8 to 20 mm.

If the diameter of the cement reinforcement is smaller or the length is longer than this, the cement reinforcement is likely to be subjected to shear forces when mixed with cement, sand, or gravel to obtain mortar or concrete, and the strength of the resin material is reduced. Convergence of the fibrous material cannot be maintained by the coating, and the convergence is loosened, causing the fibrous material to become loose, which tends to impair fluidity, which is not preferable. On the other hand, if the fiber length is shorter or the diameter is larger than this, the contact area per unit volume between the fiber material and mortar or concrete will be small, making it difficult to obtain a sufficient reinforcing effect.

The weight of the cement reinforcing material, that is, the weight of the cement reinforcing material in which the fiber material is coated with the resin material, is preferably 100-1200 dtex, more preferably 200-600 dtex. If it is lighter than this, the cement reinforcing material tends to become entangled in the mortar or concrete, causing a decrease in dispersibility. It is difficult to obtain a sufficient reinforcing effect, which is not preferable.

The content of the cement reinforcing material of the present invention in mortar or concrete is determined depending on the purpose, and is, for example, 0.01 to 10.0% by volume.

The cement reinforcing material of the present invention is used as a material for mortar or concrete together with the cement (binding material) as described above, and becomes a mortar or concrete molding containing the cement reinforcing material.

In addition to the cement reinforcing material of the present invention, the cement to be reinforced includes blast furnace slag powder, fly ash, silica fume, limestone powder, quartz powder, gypsum dihydrate, gypsum hemihydrate, anhydrous gypsum, quicklime-based expansive material, and calcium sal. A known admixture (binder) such as a foraluminate expansion material may be added.

In particular, the cement reinforcing material of the present invention has high convergence even in processes such as cement kneading, and even when kneading mortar with a low water/binder ratio or concrete with a high shear force, breakage is unlikely to occur, and the material can be used. Does not hinder fluidity and workability. A mortar or concrete molding reinforced with the cement reinforcing material of the present invention does not experience abrupt fiber breakage even when the applied stress increases, so that the bending fracture energy of the molding is greatly improved.

<Manufacturing method>
The cement reinforcing material of the present invention can be produced, for example, by coating a fibrous material, which is spun yarn or stretch-broken yarn, with a resin material and cutting it into lengths of 5 to 25 mm. The manufacturing method will be described in detail below.

First, a spun yarn or stretch-broken yarn is prepared as a fiber material, and twisted if necessary. The fiber material is then coated with a resin material. As a method of coating with a resin material, the fiber material is continuously sent from a bobbin or a beam creel, and the fiber material is continuously fed into a bath of a resin material mixture (preferably an emulsion with water as a dispersion medium). It is preferable to use a method of impregnating the resin material by immersion (hereinafter referred to as a continuous immersion method). Alternatively, a method of coating by a roller touch method or a method of coating by spraying the resin material may be used, but a continuous dipping method is preferable in order to uniformly coat the fiber material with the resin material. In this continuous dipping method, the amount of the resin material covering the fiber material can be easily adjusted to a constant amount by using a squeeze roll.

In order to effectively impregnate the inside of the fiber bundles of the fiber material with the resin material, it is preferable to use the mixed liquid of the resin material in the form of an emulsion using water as a dispersion medium or a solution in which the resin material is dissolved in an organic solvent. From the viewpoint of safety and work environment load reduction, it is preferable to use an emulsion using water as a dispersion medium.

After coating the fiber material with the resin material, the dispersion medium or solvent for the resin material is subsequently dried. At this time, heat treatment is preferably performed to crosslink the resin material. The heat treatment can be performed using, for example, a contact hot roller or a non-contact hot air drying furnace. The heat treatment temperature is, for example, 105 to 300.degree. C., preferably 120 to 250.degree. The fiber material obtained is then cut into lengths of 5 to 25 mm by known cutting machines.

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below. Various evaluations in the examples were measured as follows.
(1) Tensile strength Measured according to ASTM D885.
(2) Diameter Measured according to JIS L 1017.
(3) Fiber length Measured according to JIS L 1015.
(4) Cohesiveness after cement kneading After kneading with cement, untwisting of the cement reinforcing material in the mortar or concrete was visually confirmed and evaluated according to the following criteria. In particular, it is easy to untwist in the center of the cement reinforcing material (fiber bundle after cutting). Defined as "untwisted".
⊚: 1 or less cement reinforcing materials (fiber bundles after cutting) with untwisted out of 10 fibers.
◯: 2 to 5 untwisted cement reinforcing materials (fiber bundles after cutting) out of 10 fibers.
Δ: 6 or more untwisted cement reinforcing materials (fiber bundles after cutting) out of 10 fibers.
(5) Adhesion to mortar A fiber bundle (fiber material coated with a resin material) before being cut to a predetermined length to obtain a cement reinforcing material is embedded in mortar to a depth of 10 mm, and after the mortar hardens, A pull-out test was performed and the maximum stress at pull-out was measured as adhesion.
(6) Fluidity of fresh mortar After the kneading process, fresh mortar was added to a slump cone (a cone with a height of 15 cm, an inner diameter of 10 cm on the lower surface and an inner diameter of 5 cm on the upper surface) on a horizontally arranged 50 cm square aluminum plate. was poured in with a scraper, and the slump cone was slowly pulled up vertically. At this time, the raw mortar spreads out in a circle on the aluminum plate. The diameter of the expanded circle at this time, or when the circle was distorted, the arithmetic mean of the shortest diameter and the longest diameter was measured as the flow value. This flow value reflects the fluidity of fresh mortar.
(7) Bending strength of mortar molding Raw mortar is placed in a formwork of width 40 mm x height 40 mm x length 160 mm, cured at 20 ° C. and 90% RH until the material age is 28 days, and a specimen is obtained. manufactured. Three-point bending measurement was performed on the test piece in accordance with "JIS-R-5201". More specifically, using a 10-ton tensile and compression tester (UNIVERSAL TESTING INSTRUMENT MODEL UTM 10t, manufactured by TOYO BALDWIN), compress the center with a distance of 10 cm between fulcrums at a rate of 2 mm / min, bending stress - maximum stress of strain was calculated as bending strength.

[Example 1]
As a fiber material, a continuous long fiber of copolymerized aramid fiber (copolymerized aromatic polyamide fiber, "Technora" manufactured by Teijin Limited, 1670 dtex, 1000 filaments, tensile strength 24.5 cN / dtex) was stretched to a length of 150 cm. 440 dtex stretch-broken yarn was obtained by stretching it 3.8 times and stretching it. Next, the obtained stretch-breaking textured yarn was twisted at 320 times/m using a twisting machine to obtain a fibrous material (450 dtex, 263 filaments, tensile strength 16.0 cN/dtex). Sorbitol polyglycidyl ether-based epoxy compound ("EX614B", manufactured by Nagase ChemteX Corporation) and dimethylpyrazole-blocked hexamethylene diisocyanate ("Trixene aqua201", manufactured by Baxenden, dimethylpyrazole-block-HDI trimer) were used as resin materials. After immersing in a blended liquid (emulsion with water as a dispersion medium) with a total solid concentration of 8% by weight, which is a mixture of 50% by weight and 50% by weight, and after adjusting the amount of adhered liquid with a squeezing roll. , and dried at a temperature of 200°C to obtain a fiber bundle to which 10% by weight of the resin material was applied with respect to 100% by weight of the fiber material. This fiber bundle was cut into a predetermined length of 15 mm to obtain a cement reinforcing material. The diameter of the cement reinforcement obtained was 0.25 mm.

27.8 g of this cement reinforcing material, 951 g of low-heat Portland cement (manufactured by Taiheiyo Cement Co., Ltd.), 220 g of silica fume (manufactured by Elkem AS), 541 g of fine aggregate (manufactured by Sanei Silica Co., Ltd., "No. 6 silica sand"), fine bone Material (manufactured by Sanei Silica Co., Ltd., "silica sand SP80") 437 g, water 193 g, and a mortar mixer (manufactured by Marui, MIC-362 type, capacity: 5 L) were kneaded for about 3 minutes at a stirring speed of 140 rpm to give a raw material. Got mortar. Table 1 shows the evaluation results of mortar compacts obtained by curing this raw mortar in air for 3 days, in water for 2 days, and in air for 2 days.

[Example 2]
As a fiber material, instead of the stretch-broken yarn of Example 1, a 10-count spun yarn (591 dtex, twist coefficient K = 4.1 and a tensile strength of 9.5 cN/dtex) were used in the same manner as in Example 1. Table 1 shows the evaluation results.

[Example 3]
As the mixed liquid of the resin material, a mixed liquid (emulsion with water as a dispersion medium) having a total solid concentration of 12% by weight was used, and a fiber bundle was obtained in which 14% by weight of the resin material was added to 100% by weight of the fiber material. Others were carried out in the same manner as in Example 1. Table 1 shows the evaluation results.

[Example 4]
As the mixed liquid of the resin material, a mixed liquid (emulsion with water as a dispersion medium) having a total solid concentration of 5% by weight was used, and a fiber bundle was obtained in which 7% by weight of the resin material was added to 100% by weight of the fiber material. Other than that, the same procedure as in Example 1 was carried out. Table 1 shows the evaluation results.

[Comparative Example 1]
As the fiber material, instead of the stretch-broken yarn of Example 1, long fibers of 440 dtex of copolymerized aramid fiber (copolymerized aromatic polyamide fiber, "Technora" manufactured by Teijin Limited) were used, and the total solid was used as the resin material. The procedure of Example 1 was repeated except that a mixed liquid (emulsion with water as a dispersion medium) having a concentration of 12% by weight was used, and a fiber bundle was obtained in which 10% by weight of the resin material was added to 100% by weight of the fiber material. implemented. Table 1 shows the evaluation results.

The cement reinforcing material of the present invention can be suitably used to reinforce cement-based mortar and concrete.

Claims (6)

A cement reinforcing material comprising a fibrous material and a resin material covering it, wherein the fibrous material is a spun yarn or stretch-breaking yarn, and the amount of the resin material attached is 3 to 20% by weight based on 100% by weight of the fibrous material. % . 2. The cement reinforcement according to claim 1, wherein the fibrous material has a tensile strength of 7 cN/dtex or more. 3. The cement reinforcing material according to claim 1, wherein the resin material comprises a resin containing an isocyanate compound as a constituent component. Cement reinforcement according to any one of claims 1 to 3 , having a weight of 100 to 1200 dtex. A method for producing a cement reinforcing material according to claim 1, wherein the fiber material, which is spun yarn or cut yarn, is coated with a resin material and cut into lengths of 5 to 25 mm. How the material is made. A molding of mortar or concrete containing the cement reinforcing material according to any one of claims 1 to 4 .