JPH01255505A - Manufacture of fiber reinforced cement mortar molded body - Google Patents

Abstract

PURPOSE:To prevent creepings and blobs from being generated on a release surface by applying thinly and uniformly resin mortar on a frame surface preliminarily by spraying or coating, and then filling fiber mixed cement mortar, finishing the surface with a trowel, and then curing and releasing. CONSTITUTION:Uncured resin mortar is sprayed or applied thinly and uniformly by a trowel preliminarily on the inner surface of a frame for casting, and then fiber mixed cement mortar is fed thereon before said uncured resin mortar is fed, compacted, cured and released. Good release properties and a smooth release surface can be provided by said process without the generation of creepings and blobs and repair is not necessary. Resin mortar is prepared by mixing cement, resin emulsion or latex, water, aggregates and, if necessary, short fibers for reinforcing and an additive such as a water reducing agent or the like at the given ratio. As for the reinforcing fibers used for the fiber mixed cement mortar, various kinds of inorganic fibers such as carbon fibers, alkali-proof glass fibers and the like, various kinds of organic fibers such as aramid fibers, vinylon fibers, or metallic fibers such as steel fibers, stainless fibers and the like are used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a fiber-reinforced cement mortar molded product that has a smooth demolding surface free of avatars and has excellent appearance, strength, waterproofness, and durability.

(Prior art) A composition obtained by kneading fibers, cement, aggregate, and water was developed to compensate for the lack of strength and toughness of so-called cement products by utilizing the tensile strength and elastic modulus of fibers. At the same time, it is an effective means for preventing cracks caused by drying shrinkage of cement.

The molding methods are: 1. A direct spray method in which cement mortar is formed, and 2. A method in which a cement mortar mixture containing reinforcing fibers cut into a certain length is poured into a mold and cast (premix method, hereinafter referred to as "premix method"). (abbreviated as PMX method).

Among these methods, the PMX method conventionally involves free-falling premixed cement mortar mixed with reinforcing fibers into a formwork from a hopper, etc., pouring the entire predetermined amount into the mold, and then finishing the surface with a trowel. .

(Problems to be Solved by the Invention) However, in the conventional PMX method, as the amount of fiber is increased for the purpose of improving the physical properties of cement products, the contaminant has poor fiber dispersibility, workability, fluidity, and moldability. There was a problem in that it became difficult to fill the frame, resulting in a decrease in moldability and productivity.

Even if it is forcibly filled using a vibrator or tamping method, when it is hardened and removed from the mold, countless air bubbles remain on the surface and inside of the mold, forming avatars that significantly impair the aesthetic appearance. This is a weak point in strength, waterproofness, and watertightness of the molded body.

For this reason, in the past, it was unavoidable to increase the water-cement ratio to increase fluidity and improve moldability, or to vacuum suction a slurry with good fluidity into the mold, or to repair the surface of the molded product with resin mortar after demolding. A method was used to do this.

However, it is a well-known fact that an increase in the water-cement ratio leads to a decrease in strength and waterproofness, and vacuum suction and press-in molding require large dedicated equipment and formwork, resulting in poor production efficiency.

Furthermore, applying a repair material to the avatar portion of a molded body that has been unavoidably hardened tends to cause poor adhesion to the base material of the molded body, uneven coloring, and is also disadvantageous in terms of freeze-thaw resistance.

Furthermore, all the work is done by hand, requiring skilled workers and is time-consuming.

(Means for Solving the Problems) In view of the above-mentioned conventional circumstances, the present invention has been developed to prevent the occurrence of apata on the release surface of a fiber-reinforced cement mortar molded product, and to provide an excellent appearance, waterproof property, and durability. This was made for the purpose of providing a fiber-reinforced cement molded body.

That is, the gist of the present invention is to preliminarily apply resin mortar thinly and uniformly to the mold surface by spraying or coating, then fill it with fiber-mixed cement mortar, finish the surface with a trowel, and then cure and demold.

The present invention will be explained in detail below.

The method of the present invention is to produce a fiber-reinforced cement mortar product using the PMX method, by spraying or troweling uncured resin mortar onto the inner surface of a mold for casting in a thin and uniform layer. After application, fiber-containing cement mortar is supplied before they harden, and then compaction and curing are performed in the same way as in normal methods, followed by demolding.

That is, in the present invention, first, a resin mortar to be applied to the surface of the mold is prepared.

Resin mortar is prepared by mixing cement, resin emulsion or Hiro latex, water, aggregate, and additives such as reinforcing short fibers and water reducing agents in predetermined proportions as needed, according to a conventional method.

Of course, resin mortar made by mixing a commercially available powder premix type repair material with water, emulsion, or latex may also be used as is.

There are no particular restrictions on the raw material for cement, and in addition to ordinary Portland cement, various mixed cements such as early-strength Portland cement, blast furnace cement, silica cement, and fly ash cement may be used, as well as so-called low-alkali cements that have recently become available. Cement can also be used. The particle size of the aggregate is small! ■The following fine aggregates shall be used, but there are no particular restrictions on the types; river sand, mountain sand, crushed sand, etc.
In addition to silica sand, lightweight fine-grained shirasu balloons, perlite, silica fume, powdered silica sand, etc. can be mixed depending on the purpose.

There are no particular restrictions on the form or type of the resin to be mixed.

In other words, the aqueous solution used for normal cement-based repair materials,
It can take any form such as emulsion, latex, or powder.

The type of resin may be appropriately selected from the usual acrylic type, SBR type, ethylene acetate type, etc., which will form the desired exterior surface base.

If it is not made into a resin mortar, it will have poor adhesion to the fiber-reinforced cement mortar and will easily peel off at the interface with the fiber-reinforced cement mortar base material during or after demolding.

Although reinforcing fibers are not essential, they are preferably used in areas exposed to severe exposure conditions.

The type of fibers does not necessarily have to be the same as the fibers in the fiber-reinforced cement mortar that will be placed later, but short fibers should be used so that they do not block the air outlet or cause fluff on the coated surface during spraying or application. The length of the fibers and the amount of the fibers to be mixed may be set arbitrarily as long as they are within the above range.

Usually 0.3~/rfrr1M, the amount mixed is 0.3~/rfrr1M of cement mortar. /~! - is in the range.

These mixed wires may be mixed using a conventional method such as a mortar mixer, hand mixer, or hand kneading.

The resin mortar obtained by kneading may be sprayed onto the mold surface using a normal mortar spray device or an airless gun, or may be applied using a plastering trowel.

The softness of the resin mortar can be selected appropriately depending on the temperature on the day of construction, wind speed, unevenness of the formwork surface, construction site, etc., but it is usually preferable to have a flow value in the range of 200 to 300 as specified by JISR12θ/. .

The application thickness is usually in the range of 2 to 100 cm thick, and it is important to spray or paint it uniformly.

Before the resin mortar applied to the inner surface of the mold has dried and hardened, fiber-mixed cement mortar is applied and filled into the mold.

Similar to the cement for resin mortar, the type of cement used in the fiber-mixed cement mortar is not particularly limited and may be prepared by a conventional method.

There are no particular restrictions on the type and particle size of the aggregate, as long as it mixes well with the reinforcing fibers.For example, river sand, mountain sand, crushed sand, silica sand, lightweight fine-grained shirasu balloons, perlite, silica heat, powdered silica sand, etc. Q admixtures that can be used arbitrarily are not particularly limited as long as they are for cement and concrete, and water reducing agents, AE agents, shrinkage reducing agents, swelling agents, hardening retardants, etc. can be used arbitrarily.

As the reinforcing fibers, various inorganic fibers such as carbon fibers and alkali-resistant glass fibers, various organic fibers such as aramid fibers and vinylon fibers, or metal fibers such as steel fibers and stainless steel fibers can be used.

The length of these fibers is preferably in the range of 3 to 4'ow, preferably in the range of 3 to 2ONI4, from the viewpoint of dispersibility, reinforcing properties, and the like.

There are no particular restrictions on the kneader as long as the fibers can be uniformly dispersed, and a common method such as a common mortar mixer, pan-type mixer, concrete mixer, omni-mixer, etc. may be used.

For compaction of fiber-containing cement mortar, rod-shaped vibrators, table vibrators, plate-shaped vibrators, etc., which are used for placing ordinary concrete products, are used.

After pouring, it is sufficient to cure and harden according to conventional methods, and then to remove the mold, resulting in a high-quality fiber-reinforced cement mortar product with extremely good surface properties. In addition, when used in combination with the tile pre-spraying method, an outer surface with good tile adhesion can be obtained without residual air bubbles or tile joint breaks.

(Example) The present invention will be explained in more detail with reference to Examples below.

Example: 20 kl of ordinary Portland cement, 700 f of pearlite AJ (manufactured by Mitsui Kinzoku Perlite Co., Ltd.), acrylic emulsion [Frimal M-3θ] (manufactured by Nippon Acrylic Chemical Co., Ltd., solid content 4 tz, qb) / kg, Cape Mizuwa Knead with a hand mixer, flow value 23-6×
A 2 ton resin mortar slurry was prepared.

This is applied to a steel formwork with an average thickness of 3m using a mortar spray machine.
After spraying with carbon fiber and leaving it for about 30 minutes, carbon fiber mixed lightweight cement mortar (fiber mixing rate 2.0%, flow value: /daO”
yC/3 &'') was allowed to fall naturally from a hopper and cast into a formwork, compacted with a rod-shaped vibrator, and then finished with a trowel on the launch surface.

Further, the mold was removed after heating and curing at ♂O ℃ for about 70 hours.

The mold releasability was good, the mold release surface was smooth, and there was almost no occurrence of apata and no repair was required.0 Also, no rust was observed on the mold.

This molded body is naturally cured and the surface is brought out within a week of age! A cross cut was made at the angle of view, a steel dismo of the same size was attached, and the adhesion strength was measured using a Kenken peel tester.

Adhesion strength is average of 9, 1 kl/l:a
The carbon fiber-reinforced cement mortar base material was broken in both cases, indicating that the adhesion was extremely good.

Comparative Example: Cement mortar mixed with carbon fiber mixed under the same conditions as in the example was directly poured into a steel formwork with the same material mass and dimensions as in the example, and subjected to rod vibrator and curing in the same manner as in the example. After that, it was removed from the mold.

Avatars (residual air bubbles) were formed on the mold release surface, and red rust was attached to the formwork, so the entire panel needed to be repaired.

Comparative Example λ Light-weight brane mortar mixed with pearlite without adding resin (70-value = 203 Mortar mixed with carbon fiber of the same recipe was cast.

At this time, some parts of the brain mortar had begun to dry, and some spots were found to be white.

The mold was removed after being cured using a rod-shaped vibrator in the same manner as in Example.

The mold releasability was good, and the demolding surface was smooth with almost no avatar (residual air bubbles), but there were some cracks (scratches) on the surface caused by the hardening of the brain mortar.

When a peel test was conducted on the surface sprayed layer using the same materials and the same method as in the example, the adhesion strength was /4t, t on average at the da point.
t4/c! However, it was found that all of the peeling locations were at the interface between the lightweight brane mortar and the carbon fiber reinforced cement mortar, and that the weak point near the surface of the molded product was located at the interface.

(Effects of the Invention) As described in detail above, in the method for manufacturing PMX fiber-reinforced cement cracked products of the present invention, uncured resin mortar is applied thinly and uniformly to the inner surface of the mold in advance, and then fiber-mixed cement mortar is applied. Because there are no residual bubbles on the irregular surface, the strength and
There are no weak points in terms of waterproofing, and there is no need for repairs after demolding.In addition, the first surface layer and the fiber-reinforced cement mortar base material fit well and have strong adhesion, so it can be exposed to harsh environments for long periods of time. There is also very little risk of peeling.

Another side effect is that the formation of red rust, which is a problem when carbon fiber-containing mortar is directly poured into steel formwork, can be avoided.

Since the present invention is a method for forming a smooth, dense, and strong resin mortar layer on the surface of a fiber-reinforced cement mortar molded product by sufficiently absorbing the unevenness of the surface of the formwork, the water-cement ratio is lower than usual. It is extremely suitable for manufacturing fiber-reinforced cement mortar products, as well as fiber-reinforced cement products with complex shapes that are difficult to repair after demolding.

Claims (2)

[Claims] (1) A fiber-reinforced cement mortar molded product characterized by spraying or applying resin mortar uniformly and thinly on the surface of the mold in advance, then supplying fiber-mixed cement mortar thereon, hardening, and demolding. manufacturing method. (2) The method for producing a fiber-reinforced cement mortar molded article according to claim 1, characterized in that the resin mortar applied to the surface of the formwork contains 0.1 to 5.0 parts by weight of shortened reinforcing fibers.