JPS598664A - Fiber reinforced cement mortar and concrete composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fiber-reinforced cement mortar and concrete in which polyvinyl alcohol-A/(abbreviated as PTA) fibers are mixed into cement mortar and concrete. Cement mortar and concrete are durable and fire resistant, and are uniquely characterized by their moldability and high compressive strength of molded products. However, when used as a structure, it has the drawbacks of being a brittle material and having poor bending durability and tensile resistance. Furthermore, the strain is small and cracks occur quickly, leading to subsequent destruction, and impact resistance is lacking.Furthermore, cracks occur due to expansion and contraction of the matrix, leading to destruction of the structure and water leakage.

It has drawbacks in terms of safety and management, such as damage to the appearance due to flaking and missing parts. In addition, one of the problems is that it has a large dead weight.

As a countermeasure for these improvements, the usual method is to reinforce them with reinforcing bars. However, even this is not sufficient in terms of material components, construction, use, and economy, and in recent years, steel fiber reinforced concrete or mortar has been used, and alkali-resistant glass fibers have been used to make steel fiber-reinforced concrete or mortar. Alkaline glass fiber concrete or mortar is being put into practical use by improving the drawbacks of concrete and mortar.

Although steel fibers have characteristics such as high strength and Young's modulus per cross-sectional area and good adhesion to cement, their drawbacks include a decrease in strength due to rusting and a decrease in reinforcing properties due to a decrease in adhesive strength. It also causes damage to the surface appearance due to rust. Furthermore, since it has a high specific gravity, in order to add the volume percent necessary to exhibit the effect, the addition rate per weight becomes enormous, and the self-weight is large, resulting in a lack of economical efficiency. In addition, when producing steel fibers, there are problems in terms of production and cost, such as the hook type or dogbone type K in the Nagayoshi direction, which has an irregular cross section. On the other hand, in terms of construction, there are some cases where a debenser is required to improve dispersibility, it is impossible to handle with bare hands for safety reasons, and the kneading process takes time and reduces productivity.

Next, although alkali-resistant glass fibers are called alkali-resistant glass fibers, they still have problems with their alkali durability, so they have not reached the point where they can be used as load-bearing structural members. Furthermore, even if chopped strands of alkali-resistant glass fibers are mixed and added to concrete and mortar, the fibers will be broken and the fiber length will be As a result, the surface is damaged and cannot exert sufficient reinforcing effect.

For this reason, dry spraying has no choice but to rely on molding, which leaves problems in terms of handling and workability.

Fiber-reinforced concrete and mortar using organic synthetic fibers are also being considered. Among them, polyolefin-based polyethylene, polypropylene, vinyl-based polyvinylidene chloride, polyvinyl chloride, polyvinyl alcohol/l
', polyacrylonitrile, various types of nylon such as nylon 6 and 6,6 as representative examples of polyamide type, Kevlar as representative examples of aramid type, and various organic synthetic fibers such as polyester type and polycarbonate type. However, vinyl-based, polyamide-based, and polyester-based fibers other than polyolefin-based and PvA-based fibers are hydrophobic and have poor adhesion to the Cement F matrix, and the reinforcing effect is low because the fibers can be pulled out from the matrix when broken.

In order to prevent the fibers from being pulled out, the fibers are deformed in cross section or have protrusions or knots along their length to prevent them from slipping out. -For example, adding knobs to both ends of Japanese Patent Publication No. 49-37407, Japanese Patent Publication No. 55-67559.85457
As shown in Figure 2, an attempt was made to prevent slippage from the matrix by adding protrusions to the surface of the fibers. There is a detailed research report on molded products in "Seisaku Kenkyu" Vol. 61, No. 4, p. 25 (April 1979), but the polyethylene fibers used here have poor adhesion to the matrix, so they do not adhere to the surface. The idea is to maintain strength after cracks develop by creating protrusions. On the other hand, it has the paradoxical disadvantage that the crack opening strength decreases as the fiber addition rate increases. Other improvements must be made from the viewpoints of flowability and economy.

In addition, polyester-based organic synthetic fibers have weak γμ resistance and υ resistance, and cannot be used for durable members such as concrete and mortar.

Regarding PVA @ fiber [cement concrete] (1
966, May issue, page 2), the properties of cement mortar using PVA fibers are published. This report states that the fibers must be dispersed using a surfactant, that the difference between the strength at complete breakage and the strength after crack development is 25,100 denier, and that the curved ff strength is better when the fineness is larger. High 0
], it has been reported that the strength decreases as the amount of fiber added increases.

The present inventors have arrived at the present invention as a result of intensive research to improve the disadvantages of fiber-reinforced concrete made of steel fibers, alkali-resistant glass fibers, and organic synthetic fibers by using PVA fibers, which are organic synthetic fibers. .

The gist of the present invention is that the single fiber strength is 60 Kg/ym2 or more,
It has basic fiber physical properties such as Young's modulus of 1.5 x 10' Kq/mm2 or more, and morphological stability such that shrinkage in boiling water at 100°C is 8% or less. In addition, the fineness of the single fiber is between 100 and 1000 deniers, and its ARII (generally referred to as aspect ratio)
It is the length of the fiber divided by the diameter of the fiber. ) is 3
It consists of a PVA fiber reinforced concrete and cement mortar μ composition containing 0.2 to 4% by weight in the total solid content of PvA@fiber having a cutting length of 0 to 150.

These will be explained in more detail.

First, PVA fibers are made by saponifying polyvinyl acetate and are made of polyvinyl alcohol, a highly hydrophilic water-soluble polymer having 10H groups in its side chains. □Spinning this,
Highly crystalline PVA fibers can be obtained by stretching and heat treatment. The fiber is highly hydrophilic and water-soluble, but in order to exhibit its fiber performance, it must be highly stretched, heat-treated, acetalized, or cross-linked to make it insoluble in water. It is characterized by its stability and water insolubility. The fact that the shrinkage rate in boiling water at 100°C is 8% or less as stated in the present invention is a measure of the shape stability of PVA fibers, and it does not dissolve in hot water at 100°C.
It is essential to specify the swelling property at this temperature, that is, the morphological stability under the extremely severe conditions of water content of 20% or less after centrifugal dehydration at 3000 rpm'''C. , May issue, page 2) states that 500 denier has no reinforcing properties because there is no difference in strength between complete fracture and crack development, and that as the amount of fiber added increases, the bending strength decreases. ing.

This is because in the former case, the PVAPJ and fibers added at the time of bending and rupture expand and contract and easily slip out of the matrix.
The A fibers are supposed to exist as if they were passing through the cavity, and although they do provide a reinforcing effect, they only increase the number of defects. Monofilament fineness is 100-1000
As the denier increases, the amount of expansion and contraction in the axial and radial directions of the fibers increases, so the adhesion between the cement matrix and the PVA fibers tends to deteriorate. That is, in order not to deteriorate the morphological stability of the fibers, it is essential to maintain the shrinkage rate in water boiling at 100° C. to 8% or less, although the reason is unknown. In order to obtain such PVA fibers, the fibers can be sufficiently shrunk at a low temperature in a heat treatment process, or the cut fibers can be heat treated in hot air at 100 to 250°C. Furthermore, it can also be achieved by high stretching treatment, acetalization, and treatment with a crosslinking agent such as titanic acid. The PVA fi fibers present in cement mortar and concrete do not change in size and maintain good morphological stability, allowing them to bond with the cement matrix and PVA fi fibers.
It became possible to maintain the state in which the i fibers were connected to the stiffness υ. Furthermore, PVA fibers have an inherent hydrophilic 10H group and an affinity for the cement component of the matrix.

Therefore, unlike polyolefin-based polyethylene, polypropylene, vinyl-based polyvinyl chloride, polyvinylidene chloride, polyamide-based 6 and 6.6 nylon, and polyester-based hydrophobic organic synthetic fibers, 9% PVA fibers have protrusions on the fiber surface. Even if the fibers are attached to an irregularly shaped cross section, the bond with the cement matrix is high, and there is no need to change the fiber morphology. Creating an irregular cross-section with protrusions on the surface in order to improve adhesion is useful for increasing adhesion, but it is meaningless from the viewpoint of productivity, fiber properties, and economic efficiency. It is.

Next, the strength and Young's modulus of the single fiber are 60 and 9/lsm, respectively.
The fact that 1.5×10” Kg/mm2 or more is required can be explained by the composite agent and fiber spacing theory for the tensile and bending strength of the composite material. First of all, in order to improve the bending strength of composite materials from a composite agent, it must be useful for improving the strength after cracks occur, and it is the strength of the fibers that exerts this effect, so the higher the strength of the fibers, the more reinforcing it is. This will lead to improvements in Furthermore, the higher the Young's modulus of the fibers, the greater the crack resistance of the composite material. For this purpose, the single fiber strength needs to be 60 Kg/mm2 or more, and if it is less than 60 Kq/mm2, the reinforcing property of the cracked bale will be reduced. Also, Young's modulus is 1.5 x 10'K
g/mm2 The higher the value, the better, but 1.5
If the diameter is smaller than X 10M Kg 7mm2, the resistance to cracking will decrease, which is not preferable.

According to the fiber spacing theory, it is better to mix in a large number of fine fibers to prevent crack propagation, but it is very difficult to uniformly disperse fine fibers in dense nullary like cement mortar and concrete. , 100 to 1000 deniers is preferable in terms of uniform dispersion and mixing. 100
If the denier is greater than 0, the effect of the addition is that the number of added fibers decreases, making it useless for preventing crack propagation. Further, if the cutting length is less than 100 denier, uniform dispersion cannot be obtained, and if the cutting length is shortened in order to obtain uniform dispersion, no reinforcing effect can be obtained.

One of the reasons why the single fibers are cut and cut so that the fineness of the single fibers is 100 to 1ooo deniers and the ARit is 30 to 150 is that Nufree is used in the dry mixing state of cement mortar and concrete or after adding water. into the PV
This is because even if the A fibers are added and mixed in any order and by any method, an undispersed state such as fiber balls will not occur. The highest AR value for steel fiber is around 60, but for PV
With A* fiber, we were able to find an advantage in terms of construction that the A and R values could be up to 150. A, R value is 60-1
20 is very suitable.

Naturally, PVA fibers are safe as there is no need to take special safety precautions when handling them, as copper fibers may pierce the body. It is also possible to utilize steel fiber dispersers, and it is of course also possible to utilize conventional batcher plants and concrete mixer trucks.

Next is the addition rate of PVA fiber.The addition rate is based on the parts used,
Since it differs depending on the usage method, it will be explained in the following 1) to 3).

1) If the purpose is to prevent cracks in cement mortar, the sand/cement ratio should be between 1 and 6. Water/cemen I ratio is 0.4
If it is about ~0.8, the PVA fiber will be 0.8% in the total solid content.
2 to 0.5912 is satisfied.

2) When using cement mortar as a building structural member, if you want to obtain crack development green strength, maximum fracture strength after cracking agent, and high toughness, the total solid content should be 0.2 to 4.
Weight t% is required. Desirably 1 to 2% by weight is suitable. If it is less than 0.2% by weight, the reinforcing properties of the added PVA fibers will not be exhibited, and if it is more than 4% by weight, the m
The dispersibility of the fibers deteriorates and the flow value decreases, making it impossible to obtain workability.

The composition obtained in this way shows an increase in rupture strength after crack development in its bending strength, shows a large strain at the highest load after crack development, and is several tens of times tougher than plain. It showed excellent toughness. Also, the strength when cracks develop is slightly improved.

These can be used as high energy absorbing members, and can also be used as earthquake-resistant members, including shape retention during earthquakes.

3) When using large coarse aggregates as concrete members, the larger the AR value of the fibers, the better
It is desirable that it be contained in the total solid content of 4fi in an amount of 0.5 to 4% by weight. The reason for this is the same as stated in 2).

After crack development, an increase in the amount of strain at the highest load improves toughness and toughness.Increasing the amount of strain at the highest load improves toughness.Increasing the amount of strain at the highest load improves toughness.Increasing the amount of strain at the highest load leads to improved toughness.Increasing the amount of strain at the highest load leads to improved toughness.Increasing the amount of strain at the highest load leads to improved toughness. It can be used for civil engineering components such as tunnel lining and slope protection.
It can be used for load-bearing members such as walls. In addition, it is considered to have characteristics from the viewpoint of safety in terms of energy absorption and shape retention after crack development for earthquakes, heavy traffic roads, and heavy traffic bridges.

From the viewpoint of workability, there was no deterioration in mixability or significant decrease in slump, and the specific gravity of PVA1L was small at 1.26.
It can be easily used as pumpcrete, and there is no problem in using it as shotcrete for spray processing. Unlike steel Jiai 1M, there is no damage or wear on machinery and equipment, and it can be handled in the same way as conventional concrete and mortar.

The compressive strength does not decrease at all due to the addition of the organic polymer, and is almost the same as that without the addition of PVA1ia fibers.

Next, the materials used as compounding materials will be explained.

P'' (A@fiber) may be a delicate circular or oval shape obtained by dry or wet spinning of ordinary PVA and drawing heat treatment. It may be in the form of a pulp or a flake. It may also be in the form of a pulp by flash spinning, etc. The shape of the nozzle may be changed during spinning to give it an irregular cross section, or it may be textured by post-processing. Further, these may be heat-treated, acetalized, or cross-linked to improve the morphological stability.

P V A@@ stands alone or with steel fiber, alkali-resistant glass a
m, carbon fiber #6. It can also be used in combination with asbestos bulbs and other organic synthetic pongee such as polyethylene and nylon.

The cement is normal hydraulic cement, normal portland cement, normal portland cement.

Early-strength Portland cement, medium-heat Portland cement, sulfate-resistant Portland cement, and 5 white Portland cement are used. Mixtures (mention is not limited to this); blast furnace cement, silica cement, fly-through cement, fist powder, alumina cement, expanded cement, and early morning cement can also be used.

Fine aggregate is used as the aggregate, and various types of sand and crushed stone powder from land and sea are used. Coarse aggregate is used for bridge piers and foundations.

Maximum length 5 for thick walls, floorboards, arches, beams, thick boards, columns 9, etc.
~10 briefs will be selected. It is also possible to use artificial lightweight aggregate.

It is also possible to use an AE agent, a fluidizing agent, a water reducing agent, a thickening agent, a water retaining agent, and a water repellent in combination as admixtures.

Glauber's salt has traditionally been used as a hardening accelerator.

Gypsum, sodium carbonate, calcium carbonate, triethanolamine, and calcium chloride can also be used in combination.

Sodium silicate, potassium dichromate, and sodium silicofluoride can be used as quick-setting agents, and admixtures whose main ingredients are powder quick-setting agents such as soda carbonate and sodium aluminate can be used for repairing cracks using spraying methods. It is also possible to use

A lignin sulfonate based set retardant.

Oxycarboxylic acid type or inorganic type magnesium fluorosilicate, Rittal, etc. can be used.

In terms of construction, it is possible to perform split pouring, such as when constructing large, statically fixed structures such as viaducts, and it can be used to prevent cold joints and for sliding construction methods.

The PVmuth W4m reinforced cement mortar and concrete according to the present invention can improve the bending strength, and compared to plain, its toughness is 3.2% with 2% by weight of PVmuth fibers.
Our goal is to provide materials that are 0 to 40 times more versatile.

Furthermore, this performance can be applied to the civil engineering field as well as the architectural field from the aspect of shape retention.

The first application in the field of civil engineering is concrete road paving, including general roads, airport runways, and roads.

This field aims to improve the bending strength due to fiber reinforcement (
It is possible to reduce the amount of reinforcing bars and reduce the thickness of the concrete slab, shortening the construction period.

This is effective in reducing raw material costs, etc. Furthermore, the spraying method is effective for protecting slopes, and it is possible to spray thinly (y indicates the effect of bending strength, and since it is delicate and hydrophilic, there is less rebound.Similarly, spraying inside tunnels is also possible. The m-fibers are flexible (1) They are elastic, hydrophilic (5) They are light, so there is less splashing of the aggregate and m-fibers, and there is less falling of concrete, which is effective in terms of yield and safety.Also, when constructing bridges. It can also be used as a concrete member and as an earthquake-resistant member.Secondly, concrete products include sheet piles formed by formwork,
It can also be used for hollow cylindrical products such as pipes, piles, and balls.

As concrete products for roads, it can be used for concrete slabs for sidewalks, reinforced concrete U shapes, concrete and reinforced concrete L shapes, concrete boundary blocks, and reinforced guardrails.

Pipes include centrifugal reinforced concrete pipes made by centrifugal molding, as well as span pipes with sockets, reinforced concrete pipes, roll compacted reinforced concrete pipes, unreinforced concrete pipes, prestressed concrete pipes with complete cores, asbestos cement pipes for water supply, and other types of sewer pipes. It can also be used in products for rinsing and drainage.

As a shoring product, it can be used for reinforced concrete sheet piles and prestressed concrete sheet piles.

For balls and piles, it can also be used for centrifugal curve-rested concrete balls, centrifugal reinforced concrete balls, and centrifugal reinforced concrete piles. Prestressed concrete bridge girders for slab bridges can also be used for products for slabs and girders. Prestressed concrete girder for girder bridges. Light-load slab horizontal prestressed concrete bridge girder. Prestressed concrete dub J
It can be widely applied to l/T slabs.

Fifth, for special molding, it can be used by adding it to cement mortar extrusion molding materials, and the bending strength and impact strength can be improved. Also, spraying is done with mortar and W!
Adding PVA pongee as a coating mortar naturally prevents cracking in the heat, but it can also be used to improve impact resistance and folding strength.

It can also be used as mortar for plastering.

Paving other expressways, runways, overlays, pedestrian bridges,
It can be used for paving bridge decks, as a repair material for bridge decks, and as sidewalk boards. A formwork used as a molding formwork.

It can also be used for waste formwork. The pipes are sewage pipes.

There are scattering pipes, cable ducts, etc. Road components include soundproofing materials, road signs, pavement reinforcement materials, and side gutters.

Can be used for tunnel interior materials, piles, etc. Architectural-related components include exterior materials, which can be used for shell structures, curtain wall exterior wall panels, MMH such as molded roof tiles, parapets, spandrels, and exterior reliefs. Furthermore, it can be used as interior material for wall materials, reliefs, floor materials, and ceiling materials. Other formwork, disposable formwork, floorboards,
Beam 9 machine stand foundation, reactor pressure vessel, liquefied petroleum gas sice.

There are nine staircase materials for partitions in buildings. Marine or fishing materials include marine equipment, boats, etc. Thin beams used as cement materials for ferrocement, structural compositions, floats, floating piers, and fishing reefs.

Can be used for wave-dissipating blocks such as tetrapods, seawall blocks, etc. Tanks are agricultural and livestock-related components.

Silos, nurseries, fence pots, pots, flower pots,
Can be used for sheet piles, etc. for side gutters, etc. It can also be used for materials such as containers for processing waste such as radioactive materials. There are no limitations on the use of other materials.

Next, examples and comparative examples will be explained.

Example 1 and Comparative Example 1] i Synthetic Leather 1705. By dry spinning using PV rubber with a degree of saponification of 99.9 mol%, the fineness is 500 denier, the strength is 77 kftm', and the Young's modulus is 1.7 x 10' Gin-2.
, and a shrinkage rate of 6% in boiling water at 100° C. was obtained. Cut the delicate part into 6.12, 20.26 throats,
Add it to 1% of the total solid content of the preparation, JI8R
-5201 was used to cross-wire and mold, and the bending strength was measured.

For the mixture, ordinary Portland cement was used as the cement and Toyoura standard sand was used as the sand. The water/cement ratio is 1 to 0.4,
The flow value was measured using a Hobart mixer for stirring at a sand/component ratio of 1, and the mixture was cast into a 4 x 4 x 16 mold, molded overnight, demolded, and cured in water for 28 days.

The bending strength was measured using an Instron TT-CM. For comparison, one with a cut length of 6tlj1m and a brane without added fiber were made. The results are shown in Table-1.

The flow value, which is a measure of enforceability, was no different from plain. In addition, for Nos. 1 to 3 with large AR values, the crack development strength increases slightly and the maximum strength after crack development increases by 18 to 62% compared to plain, and the toughness is 18 to 40 times higher. It was recognized that the number of patients had increased. However, the No. 4 6-cut length of Comparative Example 1 had a small AR value and good dispersibility, but although the toughness was slightly higher, there was no difference from the Blaine in terms of bending strength.

Example 2 and Comparative Example 2 The PVA fibers produced in Example 1 were coated with 20. (AR value 84)
The addition rate of the fiber was 0.1,
Mixability, flow value 1, bending strength, and toughness were examined using the same blending method as in Example 1 except that 1, 5, 2, and 4.6% were added. The results are shown in Table-2.

Dispersibility was determined by visual observation. N010, which has a high addition rate of delicate particles, became a fiber ball and could not be molded. In addition, by changing the fiber addition rate, the toughness increased rapidly, the maximum strength after crack development increased by 2.8 times, and the crack development strength also increased. Not having a small addition rate had no effect and was the same as plain.

Example 3 and Comparative Example 3 The PVA fibers produced in Example 1 were cut into 26 pieces (MuR value 110) to make concrete containing 1% of the solid content. The dimensions of coarse aggregate are 1
Select crushed stone of 5 to 20 ■ and set the slump value as the base.
ar, 1 goal. In addition, the target air amount is 5% and the water/cement ratio is 0.6. The fine aggregate ratio was set to 0.7. unit water 3
1207kg, unit cement ji34BIcg, fine aggregate 1107kg, no admixtures used, stirred with a tendency mixer and poured into a 10X10X4El formwork JIS M1
132. According to After removing the mold the next day and curing it in water at 20°C for 28 days, the bending strength was measured by JI using a Shimadzu universal testing machine RH-200.
8A-1106, the compressive strength was measured according to JI8M1114. The results are shown in Table-3.

Table-Todoroki Example 3 achieved the highest strength while retaining its shape without breaking even when microrack occurred during three-point loading. After that, the strength of the fibers decreased as they were pulled through, but they did not break easily, and no concrete fragments were scattered.

Patent applicant: Kuraray Co., Ltd. Agent: Patent Attorney Ken Honda

Claims (1)

[Claims] The single fiber strength is 60 Kg, 4+n2 or more, and its Young's modulus is 1.5X1□” KV, 12 or more, at 100℃
Polyvinyl alcohol fibers with fiber physical properties such as shrinkage in boiling water of 8% or less, monofilament fineness of 100 to 1000 deniers, and cut to an AR value of 30 to 150 are prepared, and the total solid content contains 0. A cement mortar and concrete composition reinforced with polyvinyl alcohol fibers, characterized in that it contains 2 to 4 percent polyvinyl alcohol fibers.