JPH0459644A - Production of hardened material of cement - Google Patents

Abstract

PURPOSE:To eliminate occurrence of fiber ball in molded article, improve flexural strength and reduce occurrence of crack by blending a cement matrix with specific reinforcing fibers. CONSTITUTION:A uniaxially stretched film 1 having 20-50mum thickness is passed through porcupine rollers, cut in such a way that cuts are formed in the longer direction and intermittently and the cut parts are in parallel and mutually different, parts (a) having large width between the cut parts 2 and 2' and parts (b) having small width between the cut parts alternately exist to give a cut film, which is compression molded in a rod state and cut to give a chopped cylindrical material 3 satisfying formula I and formula II [l is length (mm) of cut part; L is length (mm) of chopped cylindrical material; (a) is width (mum) of part having large width of the cut part; (b) is width (mum) of part having small width of cut part]. Then a cement matrix is blended with 0.3-3vol.% of the cylindrical material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for manufacturing a hardened cement body, particularly a hardened cement body reinforced with trunk-branch shaped polypropylene film fibers.

[Conventional technology]

It has been well known to use polypropylene (hereinafter abbreviated as PP) fibers as a reinforcing material for cement moldings and cement mortar applied to the outer walls of buildings.

It is also known that by using trunk-branch shaped PP film fibers, the dispersibility of the fibers and the resulting reinforcing effect can be improved compared to the case of using conventional ordinary PP fibers (British Patent No. 1130612, U.S. Pat. Patent No. 42
61754 and 4310478).

The present inventor has developed a cement molded product using the above-mentioned trunk-branch shaped PP film fibers, which further improves its dispersibility and reinforcing effect by using trunk-branch shaped PP film fibers having specific shape characteristics. (Japanese Unexamined Patent Publication No. 1-122943).

On the other hand, it is known to use thick steel fibers with a cross-sectional area of 0.5 to 1.0 - to prevent the occurrence of cracks on concrete floors in parking lots and warehouses, as well as on concrete pavement surfaces such as concrete roads.

However, since steel fibers are thick, cement mall-I
The ratio of the total surface area occupied by J-Lux is smaller than that of other materials, and the crack prevention effect is very low. They also have major drawbacks, such as protruding from the pavement and damaging automobile tires. Therefore, as an alternative to such steel fibers, tens to hundreds of thin glass fibers (for example, 40 to 80 cotton in diameter) or synthetic fibers are bundled together and gently twisted, or sized and then made into a length of 20 to 40 m. Cut pieces have come to be used.

[Problem to be solved by the invention]

The reinforcing effect of reinforcing fibers on cement molded concrete floor coverings, cement mortar outer walls, etc. (hereinafter collectively referred to as hardened cement products) depends on the uniformity of fiber dispersion into the cement matrix and the strength of the fibers after uniform dispersion. It depends largely on the size of the total surface area.

However, coarse aggregate with a maximum particle size of about 13 to 20 is used for concrete pavement. If this is to be reinforced with reinforcing fibers, the length of the fibers is required to be at least 1.5 times the maximum particle diameter of the coarse aggregate. Therefore, the reinforcing fibers must have a length of at least 20 m or more, but it is difficult to uniformly disperse thin single fibers of this length (usually with an aspect ratio of 500 or more) in the cement matrix. If possible, many fiber balls will be created or they will be unevenly distributed in some areas.

The above-mentioned bundled fibers have been used to improve the dispersibility. However, even in this case, since the bundled fibers in the cement matrix are generally difficult to unravel, the total surface area of the fibers is small compared to the amount of fibers used, and the reinforcing effect is inevitably reduced. There are many problems in defibrating and uniformly dispersing the fibers, such as the kneading method and the mixing time.

Therefore, in order to uniformly disperse reinforcing fibers in the cement matrix and increase its total surface area, if the above-mentioned trunk-branch shaped PP film fibers are used, not only in cement formations but also in the above-mentioned concrete pavements, concrete floors, etc. The dispersibility and reinforcing effect are also improved in cement hardened bodies such as mortar walls.

In the first place, the reinforcing effect of hardened cement depends on the uniformity of dispersion of reinforcing fibers in the cement matrix and the total surface area of the fibers after uniform dispersion. It is desirable to avoid forming lumps (fiber bow IV) as much as possible.
Ideally, the fibers should have a large spectral ratio. However, in reality, the relationship between the generation of fiber balls and the size of the 7 spectral ratio of the fibers is such that the larger the 7 spectral ratio, the more easily the fibers become entangled, and the more easily fiber balls are generated.

According to the invention of JP-A No. 1-122943 mentioned above, the occurrence of fiber balls was much less than when other reinforcing fibers were used, and the reinforcing effect could be improved. I understand that the ball cannot be denied. The reason for this is that since the fibers are originally single fibers of PP film in the shape of trunks and branches, when these fibers are mixed into the cement matrix, engagement or entanglement of these fibers occurs, and this cannot be completely prevented. This is because it cannot be done.

Therefore, the object of the present invention is to prevent the entanglement of fibers before mixing them into the cement matrix, to facilitate their dispersion into the cement matrix, and to split the fibers into uniform single fibers when kneading with the cement matrix. It is an object of the present invention to provide a method for producing a hardened cement material which can be dispersed in fibers and further improve the reinforcing effect of the hardened cement material by almost eliminating the generation of fiber balls.

[Means to solve the problem]

The present invention provides a method for producing a cement hardened body by mixing a cement matrix and reinforcing fibers, in which a stretched film is intermittently split in the longitudinal direction as the reinforcing fibers, and the adjacent split portions are A chopped rod-shaped body obtained by compressing a split film into a rod shape and then cutting the split film so that the split parts are different from each other, and the gaps between the split parts are made to alternately have dog-shaped parts and small parts, and then cut: Length of split part (m) L: Length of chopped rod (xm) a: Width of large part between split parts (μm) b: Width of small part between split parts (μm) The present invention provides a method for producing a hardened cement body, characterized in that a satisfactory chopped rod-like body is added as a reinforcing fiber.

The production of chopped rods of split film used as reinforcing fibers for hardened cement in the present invention will be described below.

First, an unstretched film is made from a raw material pp resin by any known method, and this is uniaxially hot stretched in the longitudinal direction preferably at a stretching ratio of 15 times or more to produce a -@gritstretched film with a thickness of 20 to 50 μm. Next, it is passed through a porcupine roller and split in the longitudinal direction.

This condition will be explained with reference to FIG.

FIG. 1 is a partially enlarged plan view of a film split by passing it through a porcupine roller. In FIG. 1, reference numeral 1 denotes a uniaxially stretched PP film as described above, and split portions 2 and τ are formed in the longitudinal direction as shown in the figure using a porcupine roller as described above. At this time, the split portions 2 (or 2') extending along the same longitudinal line are formed intermittently as shown, and the adjacent split portions 2 and τ are parallel but slightly different from each other.

Moreover, the width (interval) between the two split parts 2 and the adjacent split parts τ is determined by the dog part a and the smaller part.

At this time, the length l of each split portion 2 and τ is the same, and the split is made so that the following condition is satisfied: 3/10≦l/L≦7/10 (L: length of the chopped rod) The width a of the larger part between the parts and the width of the smaller part 1/
It is split so that the condition 40≦b/a≦1/10 is satisfied. If l/L is smaller than 3/10, the formed chopped rod will maintain its rod-like shape (referred to as shape retention of the chopped rod) and will not lose its shape before being put into the cement matrix. However, in the process of putting it into a cement matrix, dispersing it, and splitting it into single fibers by the kneading action, it is not split enough and remains as a chopped rod (becomes a 1@ fiber ball). There will be more things. In addition, if the l/L is worse than 7/10, the shape retention of the chopped rod-shaped body before being poured into the cement matrix will be poor, and the shape will already collapse and become entangled with each other before being poured into the cement matrix. Dispersion into the cement matrix becomes poor and fiber balls are more likely to occur. Furthermore, if b/a is smaller than 1/40, the shape retention of the chopped rods will already deteriorate during the handling stage before being introduced into the cement matrix, causing the shape to collapse, becoming entangled with each other, and dispersing into the cement matrix. It gets worse, and on the contrary b /
When the a force is larger than ζ1/10, shape retention is good, but during the process of splitting into single fibers by kneading in the cement matrix, the splitting becomes insufficient and many remain as rod-shaped fibers. Become.

Therefore, the length l of each split portion and the length L of the chopped rod
satisfies the condition that 3/10≦l/L≦7/10, and the width a of the dog part between the split parts and the width of the small part are 1
It is preferable to split the material so as to satisfy the following conditions: /40≦b/a≦1/10. The length l of the split parts 2 or 2' is desirably 15 to 35 dragons, and the width a of the larger part between the split parts is 20 (1 μm to 2000 μm). is desirable.

Next, the uniaxially stretched split film split as described above was
After cutting (slitting) parallel to the longitudinal direction, that is, parallel to the split portions 2, 2', to the same width, the pieces are passed through a compression bundle forming device with one grooved roller and subjected to a roller line load of 1 to 1. sjc
Compression mold at g/σ to form a continuous rod. It is desirable that the cutting width W at this time is 20 meters to 500 meters.
Further, it is desirable that the thickness of the compression-molded rod-shaped body is 2 to 15 mm in diameter. Next, the continuous rod-shaped body is cut into a length L to produce a chopped rod-shaped body shown at 3 in FIG. Practically speaking, the cutting length of the rod-shaped body is preferably 5fi to 50π.

According to the present invention, when mixing the split film chopped rods 3 made as described above into the cement matrix, each chopped rod 3 may be separately introduced into the cement matrix and mixed. Even if you put it in a summary, it won't make any difference.

The ratio of the chopped rods 3 of the split film to the cement matrix is the ratio used in manufacturing a conventional PP film fiber-reinforced cement cured product, for example, the cement matrix (including cement binder, aggregate, and other additives). It can be used at a ratio of 0.3 to 3% by volume.

In producing a hardened cement body, the chopped rod-like bodies 3 of the split film are mixed into the cement matrix as described above, and then thoroughly kneaded by a conventional method, for example, using a kneading mixer. During this kneading process, the chopped rods 3 are initially dispersed in the cement matrix as they are (they are quickly dispersed because there is no entanglement).

When this kneading is further carried out sufficiently, the chopped rod-like body 3 of the split film is opened during the kneading (as shown in FIG. 3A), and the small width portion is cut off, as shown in FIG. 3B. While forming fibrillated single fibers 4 having a trunk-branch shape as shown, they are dispersed and fixed in the cement matrix.

A kneading time of 3 to 5 minutes is usually sufficient for the kneading of the tomato sand. In the conventional method of making a cement hardened body by starting with trunk-branch-shaped fibrillated PP film fibers (single fibers as shown in Figure 3B) and mixing and kneading them into the cement matrix, The main and branch-shaped fibrillated fibers themselves are easily entangled, and depending on the type of mixer during the kneading operation, they may wrap around the blades of the mixer to form fiber balls, which prevents them from fully demonstrating their function as reinforcing fibers. was there.

According to the present invention, instead of mixing reinforcing fibers in a fibrillated state from the beginning as shown in FIG. Even if a plurality of rods 3 are added together, since they are chopped rods, they will not become entangled with each other, and in a relatively short period of time, at the initial stage of mixing or kneading. A portion of it is opened into a film as shown in FIG. 3A, but is uniformly dispersed in the cement matrix. When the wires are mixed further, the chopped rod-shaped body 3 is further opened, and while the chopped rod-shaped body 3 is being opened, the already opened film is mixed with the cement matrix at the time of the wires being mixed. The fibrillated single fibers 4 are cut by the acting force and have a trunk-branch shape as shown in FIG. 3B, and are uniformly dispersed and fixed. At this time, before the trunk-branch-shaped fibrillated single fibers 4 are formed, dispersion is performed in advance with the split film chopped rods 3 or a part thereof opened in the form of a film, so that uniform dispersion is easily achieved. Since the split film rod-shaped body 3 and the partially opened film-shaped film are not entangled with each other, even if they are subsequently divided into trunk-branch-shaped fibrillated single fibers 4, these entanglements will not occur. None, or very few if any,
Therefore, the formation of fiber balls can be eliminated or very reduced. For this reason, the surface area per unit amount of PP film fibers introduced is effective and large.
Contributes to improving the strength of hardened cement.

〔Example〕

The present invention will be explained below with reference to Examples.

Production Example Production of Chopped Rod-shaped Split Film A normal PP resin raw material with an MFI of 2.3 is passed through a normal extruder at a temperature of 22
Extruded at 0°C, blow ratio 1:1, air cooled, then extruded at 180°C for 2
The film was uniaxially hot stretched in the longitudinal direction by 0x and then annealed at 160'C to produce a film with a thickness of about 30 Am and about 50 pm. Next, using a porcupine roller, change the circumferential speed of the roller to 3 to 5 times the speed of the film, and change the contact area between the film and the roller to increase the length (1) of the split portion. The pieces were split by changing the distance between the split parts (large width a and small width b). In this way, the length of the split part ()) is 3n~24
10 types of split films with a thickness of about 30 μm are made, and 10 types of split films with a thickness of about 30 μm are made.
The pieces having a width of 50 μm and a thickness of about 50 μm were each cut (slit) into a width of 250 m parallel to the longitudinal direction. next,
These split films were subjected to electrical discharge treatment, and then treated with a treatment agent containing a polyoxyethylene glycol ester surfactant and methylcellulose in a ratio of 4:1.
Using a grooved roller-type king-shrinking bundle-forming device, the bundle was compression-molded at a roller line load of 1.2A9/(:rrL) to form a continuous rod-shaped body with a thickness of about 3,511IK to 7N.Finally , These continuous rod-shaped bodies were cut into a cutting machine, and those with a slit width of 100 μl were cut into lengths of 15 dens (and those with a slit width of 250 kilometres were cut into lengths of 30 dens, respectively).
There are 10 types of chopped rods with different specifications. The specifications of these chopped rods are shown in Tables 1 and 2.

* indicates a chopped rod for comparison.

Table 2 * indicates a chopped rod for comparison.

Example 1 and Comparative Examples 1 to 6 In Example 1 and Comparative Examples 1 to 6, molded bodies were made by the casting method as follows. The materials used are shown below.

Holtland cement; #6 silica sand Mighty 150 (Kao) 15.0 9.0 4.09 0.15 Water 30.42 15.00 Using an omni mixer with a capacity of approximately 301, first mix #6 silica sand,
Add Portland cement, water and Mighty 150 and mix at about 300 rpm for 20 seconds, then ppi
+ Insert the split film chopped rod and continue to 408
- kneaded for a while. Next, add 3 kg of mortar that has been hoisted up,
The size is 316 tubes x 316 m (0,1ze) and there is 1 on the bottom.
After spreading the cement and silica sand into a box with a depth of 100 mm and a wire mesh of 0 mesh, spread it with a trowel so that the thickness is almost uniform, and then shake it gently on the water surface and gently shower it. The film was poured into water, and the state of the fiber holes in the film fibers remaining on the wire mesh and the state of division of the chopped rod-like bodies (sacrific vertebrae are divided into listic vertebrae) were visually observed. The number of fiber balls and rods remaining in the cement matrix was calculated per block. The results of observation and measurement are shown in Table 3.

*(1): 15m length product of JP-A No. 1-122943.

*(2): Normal type PP chopped fiber thickness 2
Denier, length 15 - Example 2 and Comparative Examples 7 to 13 The present Examples and Comparative Examples were carried out by cast molding as follows. The materials and formulation used are shown below.

Material Weight (c) Volume conversion (1)
Portland cement 42 12.
7 sand (particle size 3 or less) 104 3
6.5 sand was added and stirred for 30 seconds, then cement was added and stirred for 30 seconds, and finally water and Mighty 150 were mixed and kneaded for 60 seconds. Well-crafted conch') -) 5
kg into a wire mesh (mesh size 5 tm
The sand and cement were poured out and the condition of the film fibers remaining on the wire mesh was visually observed. The results of observation and measurement are shown in Table 4. Although some gravel remains, it does not interfere with observation of fiber balls, etc.

Mighty 150 0.1
0.1 Water 25 25.0 Using a forced mixing type concrete mixer with a capacity of about 2001, gravel and PP split film chopped rods were first added and stirred for 30 seconds, and then [Effects of the Invention] The above embodiments and As is clear from the data of the comparative example, by manufacturing the PP split film chopped rod according to the present invention into a cement hardened body, the occurrence of fiber balls in the molded body is eliminated, and bending strength and crack occurrence can be improved. .

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged developed plan view of the chopped rod-shaped PP split film used in the present invention, FIG. 2 is a perspective view of the chopped rod-shaped body, and FIGS. 3A and 3B. FIG. 2 is an explanatory diagram of the formation of trunk-branch-shaped fibrillated fibers within a cement hardened body. 1-11 monoaxially stretched PP film, 2.2'--10 split portion, 3-m-chopped rod-shaped body, 4-11 trunk-branch-shaped fibrillated fiber,! --- Length of splitting part, L-length of chopped rod, W --- Width of film, a, b ---
10% width. Patent Applicant Teza Co., Ltd. Figure A Figure B Five-sol version of katawaza Ikfujisoi

Claims (1)

[Scope of Claims] 1. In a method for producing a cement hardened body by mixing a cement matrix and reinforcing fibers, the reinforcing fibers are formed by splitting a stretched film intermittently in the longitudinal direction, and in which adjacent split portions are used as the reinforcing fibers. A chopped rod-shaped body obtained by compression-molding a split film into a rod shape and cutting the split film so that the widths of the split parts are different from each other, and the width between the split parts is alternately large and small, and 3/ 10≦l/L≦7/10 and 1/40≦b/a≦1/10 l: Length of split portion (mm) L: Length of chopped rod (mm) a: Large gap between split portions Width of a portion (μm) b: Width of a small portion between split portions (μm) A method for producing a hardened cement body, characterized in that chopped rods satisfying the following conditions are added as reinforcing fibers. 2. The manufacturing method according to claim 1, wherein the stretched film is a polypropylene film uniaxially stretched in the longitudinal direction. 3. The manufacturing method according to claim 1 or 2, wherein the length of the split portion in the longitudinal direction is 1.5 to 35 mm. 4. The manufacturing method according to claim 1 or 2, wherein the length of the compressed and cut chopped rod-like body is 5 to 50 mm. 5. The widest part between the split parts is 200 to 2000 μm
The manufacturing method according to any one of claims 1 to 4, wherein the small portion is 5 to 20 μm. 6. The cutting width of split film before being compressed into a rod shape is 20~
The manufacturing method according to any one of claims 1 to 5, wherein the length is 500 mm. 7. The manufacturing method according to claim 1, wherein the chopped rod has a thickness of 2 to 15 mm.