JP6741328B1 - Coarse aggregate for concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coarse aggregate capable of further improving the compressive strength and the tensile strength of concrete. SOLUTION: This is a metal coarse aggregate for concrete 1A having a plurality of spherical parts 3 and an annular part 5 projecting from the surface of the spherical parts 3 so as to surround the outer circumference of the plurality of spherical parts 3 and comprising: The width of the coarse aggregate in the connecting portion between the spherical portions 3 on the surface formed by the outer edge of the portion 5 is equal to or larger than the minimum diameter of the spherical portion 3. [Selection diagram] Figure 1A

Description

The present invention relates to coarse aggregate for concrete.

Concrete is usually so-called green concrete obtained by mixing water, coarse aggregate (crushed stone or gravel) and fine aggregate (sand) into cement, and solidified based on the hydration reaction between water and cement. It is widely used as a building material.

Concrete has the drawback of very low tensile strength and flexural strength compared to compressive strength. In order to make up for such drawbacks, it is common to dispose reinforcing bars assembled in a matrix in the length and width in concrete, but to include propylene fibers as reinforcing fibers in green concrete (Patent Document 1) and It is known to contain organic fibers, deformed steel fibers and the like (Patent Document 2). Further, as an attempt to increase the compressive strength and the tensile strength depending on the shape of the coarse aggregate itself, two spheres with a collar obtained by joining two hemispherical shaped products formed by extruding a metal plate so as to face each other. Has been proposed in which coarse aggregates are continuously provided at narrow connecting portions (Patent Documents 3 and 4), and coarse aggregates in which both ends of a metal pipe are alternately closed (Patent Document 5). ..

JP, 2017-178755, A JP, 2001-220201, A Japanese Utility Model Publication No. 45-7674 Japanese Utility Model Publication No. 45-7675 Patent No. 6485932

When the reinforcing fiber is mixed into the green concrete as described in Patent Documents 1 and 2, since the reinforcing fiber is not an essential constituent component of the concrete that has been conventionally used, the use of the reinforcing fiber provides predetermined concrete properties. There was a concern that it would be difficult to adjust the composition of the constituent components of the concrete, and there was a problem that cracks would easily occur in the concrete.

On the other hand, the metal coarse aggregates described in Patent Documents 3 to 5 can have higher tensile strength than conventional coarse aggregates. Further, since it can be used in place of the conventional coarse aggregate composed of crushed stone or gravel, the composition of the constituent components of concrete can be easily adjusted.

However, the shape in which the flanged spheres described in Patent Documents 3 and 4 are continuously provided at the connecting portion has a limit in improving the tensile strength due to the narrow connecting portion, and the narrow connecting portion There is also a problem that productivity is poor because a hemispherical molded product is joined to form a spherical body for forming and then a punching step is required. It has been desired to further increase the compressive strength and the tensile strength of the coarse aggregate described in Patent Document 5.

To such problems of the conventional technology, the present invention can be used as a coarse aggregate which is one of the essential constituents of concrete, and can further improve the compressive strength and tensile strength of concrete. The challenge is to provide a new material that can be manufactured with high productivity.

The present inventor has provided a coarse aggregate with a plurality of spherical portions having a shape similar to a sphere, and the coarse aggregate has a sufficient width equal to or larger than the minimum diameter of the spherical portion even at a connecting portion between the plurality of spherical portions. Then, since this shape is strong against compression and pulling in any direction, the concrete using this coarse aggregate has significantly improved compressive strength and tensile strength, and the spherical portion is connected to the spherical portion. The shape of the coarse aggregate having a width equal to or larger than the minimum diameter eliminates the need for a punching step for forming the connecting portion, and improves the productivity of the coarse aggregate, and the spherical shape surrounds the outer periphery of the multiple spherical portions. When the annular part is projected from the surface of the part, the adhesive property between the coarse aggregate and the mortar is improved by the annular part, which also improves the strength of the concrete and improves the dispersibility in the fresh concrete, and The present invention has been completed with the idea that the rolling property of the coarse aggregate is suppressed by the annular portion and the handleability of the coarse aggregate is improved.

That is, the present invention is a metal coarse aggregate for concrete having a plurality of spherical portions and an annular portion protruding from the surface of the spherical portion so as to surround the outer periphery of the plurality of spherical portions, the outer edge of the annular portion. The width of the coarse aggregate in the connecting portion of the spherical portions in the surface formed by, provides a coarse aggregate for concrete is a minimum diameter or more of the diameter of the plurality of spherical portions, in particular, a flexible wire A mode is provided in which the wire penetrates the spherical portion and the wire projects from the annular portion or the spherical portion.

Further, the present invention, as a method for manufacturing the above-described metal-made concrete coarse aggregate, by press working of a metal plate to form a flanged ball cutout in which the bottoms of the ball cutouts are continuous with a flange, Provided is a method for manufacturing a coarse aggregate for concrete in which flanges of two ball-cut portions with flanges are welded to each other, and a coarse aggregate for concrete in which a spherical portion and an annular portion are formed by pressing a metal rod or a metal pipe. A manufacturing method is provided.

In addition, the present invention is the above-mentioned metal-made coarse aggregate for concrete, in which the flexible wire penetrates the spherical portion, and the wire protrudes from the annular portion or the spherical portion. By pressing the metal plate, the bottoms of the ball cutouts are formed into flanged ball cutouts that are continuous with each other, and the bottoms of the two flanged ball cutouts face each other via a flexible wire. Then, a method for producing a coarse aggregate for concrete by welding opposing flanges to each other is provided, a flexible wire is passed through a metal pipe, and a spherical portion and an annular portion are formed by pressing the metal pipe through the wire. Providing a method for producing a coarse aggregate for concrete that forms and protrudes the wire from an annular portion, forms a spherical portion and an annular portion by pressing a metal rod or a metal pipe, opens a through hole in the spherical portion, and penetrates the spherical portion. Provided is a method for manufacturing coarse aggregate for concrete in which a flexible wire is passed through a hole.

The coarse aggregate for concrete of the present invention has a plurality of spherical parts having a shape similar to a sphere or a sphere, and the coarse aggregate has a sufficient width not only in a plurality of spherical parts but also in their connecting parts, It exhibits strong strength against compression and tension in either direction.

Further, since the coarse aggregate for concrete of the present invention has the annular portion protruding from the surface of the spherical portion so as to surround the outer periphery of the plurality of spherical portions, the adhesive force between the coarse aggregate and the mortar portion of the concrete is improved. By doing so, the strength of concrete is also improved, and it is easily and uniformly dispersed in fresh concrete. Therefore, the concrete using the coarse aggregate for concrete of the present invention has significantly improved compressive strength and tensile strength.

In addition, the coarse aggregate for concrete of the present invention has a sphere or a shape similar to a sphere, but the rolling ease of the coarse aggregate is suppressed by the protruding annular portion, and the handleability is improved. ..

Further, in the coarse aggregate for concrete of the present invention, a plurality of spherical portions are surrounded by an annular portion, and the connecting portion of the spherical portions has a minimum diameter of the spherical portion or more, so that high productivity can be achieved by pressing a metal plate Can be easily formed, the punching step for forming the connecting portion can be omitted, and the manufacturing cost can be reduced. Therefore, it is useful as a building material that is consumed in large quantities.

FIG. 1A is a perspective view of a coarse aggregate 1A for concrete of an example. FIG. 1B is a plan view of a coarse aggregate 1A for concrete of an example. FIG. 1C is a cross-sectional view of 1A of the coarse aggregate for concrete of the example. FIG. 2 is an explanatory diagram of a method of manufacturing the coarse aggregate 1A for concrete of the example. FIG. 3 is a perspective view of a coarse aggregate 1A' for concrete of an example. FIG. 3A is a perspective view of a coarse aggregate 1B for concrete of an example. FIG. 3B is a plan view of the coarse aggregate 1B for concrete of the example. FIG. 5A is a perspective view of a coarse aggregate 1C for concrete of an example. FIG. 5B is a plan view of the coarse aggregate for concrete 1C of the example. FIG. 6A is a perspective view of a coarse aggregate 1D for concrete of an example. FIG. 6B is a plan view of the concrete coarse aggregate 1D of the example. FIG. 7 is a perspective view of a coarse aggregate 1E for concrete of an example. FIG. 8 is a perspective view of a coarse aggregate 1F for concrete of an example. FIG. 9 is a perspective view of a coarse aggregate 1G for concrete of an example. FIG. 10 is a perspective view of the coarse aggregate 1H for concrete of the example. FIG. 11: is explanatory drawing of the manufacturing method of the coarse aggregate 1H for concrete of an Example. FIG. 12 is a perspective view of a coarse aggregate 1I for concrete of an example. FIG. 13: is explanatory drawing of the manufacturing method of the coarse aggregate 1I for concrete of an Example. FIG. 14A is a perspective view of a coarse aggregate 1J for concrete of an example. FIG. 14B is a perspective view of the coarse aggregate for concrete 1J of the example, in which the wire is wound around the main body of the coarse aggregate. FIG. 15: is explanatory drawing of the manufacturing method of the coarse aggregate 1J for concrete of an Example. FIG. 16 is a perspective view of a coarse aggregate 1K for concrete of an example. FIG. 17 is an explanatory diagram of a method for manufacturing the coarse aggregate 1K for concrete of the example. FIG. 18 is a perspective view of a coarse aggregate 1L for concrete of an example. FIG. 19 is a perspective view of a coarse aggregate 1M for concrete of an example. FIG. 20 is a photograph of the surface of the metal aggregate in which the molten metal droplets are welded. FIG. 21 is a perspective view of a joined body 1N of coarse aggregate for concrete of the example.

Hereinafter, the coarse aggregate for concrete of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals represent the same or equivalent constituent elements.

(Shape of coarse aggregate)
1A is a perspective view of a coarse aggregate 1A for concrete according to an embodiment of the present invention, FIG. 1B is a plan view thereof, and FIG. 1C is a sectional view taken along line AA. The coarse aggregate 1A is made of metal, and two ball-missing portion joined bodies (that is, spherical portions) 3 composed of two hollow ball-moving portions 2 are arranged in parallel. Here, the sphere cutout is a shape obtained by dividing the sphere on a split plane, and the sphere cutout means a portion of coarse aggregate having such a shape. In addition, in the present invention, the shape of each of the ball cutouts 2 preferably includes 1/2 or more ball cutouts, and in the coarse aggregate 1A of the present embodiment, the shape of each ball cutout 2 is a hemisphere. Therefore, the external shape of the spherical portion 3 of the coarse aggregate 1A becomes a sphere, and the crushing load is applied regardless of the plane load applied from any direction as compared with the case where the external shape is a polyhedron or an irregular three-dimensional shape. High strength even when damaged.

On the coarse aggregate 1A, an annular portion 5 protruding from the surface of the spherical portion 3 is formed so as to surround the outer circumferences of the two spherical portions 3 with a surface including the bottom surface 2g of each spherical portion 2. As shown in FIG. 2, the annular portion 5 is prepared by forming a pair of continuously formed flanges 4 on the outer periphery of the bottom surface 2g of the two ball cutouts arranged side by side, and joining the flanges 4 to each other. Is. The annular portion 5 is formed over the entire circumference of the two spherical portions 3.

The diameters D of the two spherical portions are equal, and the width W of the coarse aggregate in the connecting portion P of the two spherical portions 3 is equal to or larger than the diameter D of the spherical portion 3 on the surface formed by the outer edge of the annular portion 5. It is wide. Here, as the width W of the coarse aggregate in the connecting portion P, when the two spherical portions 3 are separated from each other as shown in FIG. 1B, the width W passes through the gap between the two spherical portions 3, Consider the shortest length of the coarse aggregate in the direction perpendicular to the line connecting the centers of the two spherical portions 3. Since the length of the coarse aggregate 1A is wider than the diameter D of the spherical portion 3, the coarse aggregate 1A can be easily manufactured by pressing as described later. In addition, the tensile strength of the coarse aggregate 1A does not excessively decrease at the connecting portion P, and the concrete using this coarse aggregate 1A is pulled by the two spherical portions 3 of the coarse aggregate 1A serving as anchors. The strength is significantly improved.

Further, according to the coarse aggregate 1A, the annular portion 5 strengthens the adhesive force between the coarse aggregate 1A and the mortar when the coarse aggregate 1A is mixed with the mortar. Therefore, in combination with the above-described strength improving effect due to the presence of the two spherical portions 3 in the coarse aggregate 1A, the concrete using the coarse aggregate 1A in place of the conventional coarse aggregate has a high compressive strength. And the tensile strength is remarkably improved.

In the coarse aggregate 1A of the present embodiment, the two spherical portions have the same diameter, but when the diameters of the two spherical portions are different, the width W of the coarse aggregate at the connecting portion P is the smaller diameter. That is all. Further, in the coarse aggregate 1A of the present embodiment, the outer shape of the annular portion 5 in plan view is a rectangular shape with rounded corners, but the outer shape of the annular portion 5 is not limited to this in the present invention, and is shown in, for example, FIG. The annular portion 5 may be rectangular like the coarse aggregate 1A'. This makes it easier to create a mold that punches the flanged ball cutout from the metal plate, and reduces the scraps when punching the flanged ball cutout from the metal plate, improving the productivity of coarse aggregate. To do. On the other hand, the annular portion may have an elliptical shape, and the connecting portion P may be slightly narrowed as in the coarse aggregate 1B shown in FIGS. 4A and 4B. However, in this coarse aggregate 1B as well, the width W of the coarse aggregate at the connecting portion P is not less than the minimum diameter D of the spherical portion 3. The upper limit of the width W of the coarse aggregate in the connecting portion P is defined by the upper limit of the size of the coarse aggregate described below.

(Size of coarse aggregate)
Since it is possible to pump fresh concrete mixed with coarse aggregate 1A through a hose, the maximum diameter of coarse aggregate 1A can be set to the same size as gravel or crushed stone which is conventional coarse aggregate. preferable. Specifically, it is preferable that the maximum diameter of the coarse aggregate 1A is within the range of the grain size and grain shape specified in JIS A 5308. For this reason, it is usually preferable that the diameter D of the spherical portion 3 be 10 to 30 mm, and the protrusion length L of the annular portion 5 in the radial direction of the sphere of the spherical portion 2 is set to the radius r of the spherical portion of the spherical portion 2. It is preferably 2/5 to 1 times. On the other hand, when the protruding length L of the annular portion 5 is too small, the adhesive force between the coarse aggregate and the mortar is reduced, and the coarse aggregate 1A is likely to roll excessively, resulting in poor handleability. When the flanges 4 formed outside the bottom of the ball cutout 2 are joined to form the annular portion 5, the protruding length L of the annular portion 5 (that is, the protruding length of the flange 4) is If it is too small, it will be difficult to firmly join the flanges together.

In the coarse aggregate 1A of the present embodiment, the height H of the ball cutout 2 and the radius R of the ball of the ball cutout 2 are equal, but in the present invention, the spherical portion 3 similar to the outer shape of the coarse aggregate 1A is provided. From the point of inclusion, it is preferable that the height H of the ball cutout 2 is equal to or larger than the radius R of the ball of the ball cutout 2. On the other hand, if the height H is too large, pumping of concrete through the hose may be hindered. Therefore, the height H of the ball cutout 2 is preferably 1.5 times or less the radius R of the sphere of the ball cutout 2.

(Thickness of the ball cutout)
In the present invention, the wall thickness t of the ball cutout 2 (that is, the wall thickness of the spherical portion 3) is the kind of metal forming the rough aggregate 1A, the method of forming the shape of the ball cutout, and the rough aggregate. It can be determined according to the intended use of the concrete used. For example, when using coarse aggregate for use in heavy concrete for radiation shielding, it is preferable to increase the wall thickness t of the ball cutout 2 to increase the specific gravity of the coarse aggregate. There is no upper limit. It is also possible that substantially no hollow portion is formed inside the coarse aggregate. In this case, the ball cutout 2 can be manufactured by hot pressing.

On the other hand, in the case of forming coarse aggregate for normal concrete, when the ball cutout is formed by cold pressing, if the wall thickness t of the ball cutout 2 is too thick, it is difficult to form the ball cutout by press working. If it is too thin, the strength will be insufficient even when the coarse aggregate is used for ordinary concrete. Therefore, the wall thickness t of the ball cutout portion 2 is preferably 1 to 6 mm, more preferably 2 to 4 mm.

(Metal component of coarse aggregate)
Examples of the metal that constitutes the coarse aggregate 1A of the present invention include iron, aluminum, titanium, copper, and stainless steel, which can be selected according to the use of concrete. For example, when the coarse aggregate of heavy concrete is used for shielding radioactivity in nuclear facilities, it is preferable to use a metal such as iron having a high density from the viewpoint of shielding X-rays and γ-rays. When it is possible to perform the work by using an electromagnet during manufacturing or transportation of the coarse aggregate 1A itself or various concrete products including the coarse aggregate 1A, the coarse aggregate is made of a magnetic material such as iron. Is preferably formed from

(Method for producing coarse aggregate)
In the coarse aggregate 1A of the present embodiment, as shown in FIG. 2 by pressing a metal plate, two ball cutouts are continuous with a flange 4 protruding from the bottom of the ball cutouts. It can be easily manufactured by producing a pair of parts, making them face each other, and joining the flanges 4 by welding. In the present invention, since the width of the coarse aggregate in the connecting portion between the spherical portions is equal to or larger than the minimum diameter of the spherical portion, it is not necessary to perform the cutting process for adjusting the outer shape of the coarse aggregate after welding the flanges 4 to each other. The manufacturing process can be simplified.

It is preferable that the flanges 4 are welded to each other over the entire circumference thereof. On the other hand, the flanges 4 may be joined together by caulking instead of welding.

In the present invention, the method for producing the coarse aggregate is not limited to the press work of the metal plate, and it can be produced by the press work of a metal pipe or a metal rod as described later.

(Deformation mode of shape of coarse aggregate)
The coarse aggregate of the present invention is made of metal, has a plurality of spherical portions, and an annular portion protruding from the surface of the spherical portion so as to surround the outer periphery of the plurality of spherical portions, and is formed by the outer edge of the annular portion. Various shapes can be adopted in which the width of the coarse aggregate in the connecting portion between the spherical portions on the surface is equal to or larger than the minimum diameter of the spherical portion.

For example, in the coarse aggregate 1A shown in FIG. 1A, two spherical portions 3 are juxtaposed via the annular portion 5, but in the coarse aggregate 1C shown in FIGS. 5A and 5B, the two spherical portions 3 are provided. They are directly connected to each other, and each spherical portion 3 exceeds one-half sphere. For this reason, the joint between the two spherical portions 3 is of a peanut type with a constriction. In this way, the peanut-type coarse aggregate in which the spherical portions with more than 1/2 sphere are joined together can also increase the tensile strength of concrete more than the coarse aggregate made of one spherical portion.

As shown in FIG. 5B, the width W of the coarse aggregate 1C at the connecting portion P when the spherical portions are directly connected is equal to that of the chord of the spherical portion formed by directly connecting the two spherical portions 3 to each other. It suffices to consider the length W at which the extension line La is cut off by the outer shape of the coarse aggregate 1C. In the coarse aggregate 1C, the width W is equal to or larger than the minimum diameter D of the spherical portion 3.

The coarse aggregate 1D shown in FIGS. 6A and 6B is one in which the three spherical portions 3a, 3b, 3c are directly connected to each other. In this case, as the width W of the coarse aggregate at the connecting portion between the spherical portions, as shown in FIG. 6B, the extension line La of the chord of the spherical portion formed by directly connecting the three spherical portions is coarse. Considering the length W cut out by the outer shape of the aggregate 1D, it is sufficient that the length W is equal to or larger than the minimum diameter of the spherical portion for any spherical portion.

In the coarse aggregate 1E shown in FIG. 7, the spherical portion 3 is located at each vertex of the tetrahedron, and each spherical portion 3 is surrounded by the annular portion 5. As a method of manufacturing the coarse aggregate 1E, first, a metal plate is press-molded so that each vertex of a triangle has a ball cutout 2, and a flange 4 is formed so as to surround these three ball cutouts 2. The four flanged ball cutouts are formed, and then the flanges 4 are joined to each other so that a substantially tetrahedral shape is formed.

The coarse aggregate 1F shown in FIG. 8 is obtained by alternately bending the corners of the rectangular annular portion 5 of the coarse aggregate 1A' shown in FIG. 3 up and down. By bending the annular portion 5 in this manner, the adhesive force of the mortar to the coarse aggregate 1F can be further improved. Further, the bending of the annular portion 5 can be performed at the same time as the pressure bonding of the pair of flanged ball cutout portions by pressing, so that the productivity of the coarse aggregate 1F does not decrease.

The coarse aggregate 1G shown in FIG. 9 is different from the coarse aggregate 1A′ shown in FIG. 3 in that a cut is made from the apex of each corner of the rectangular annular portion 5 toward the center of the coarse aggregate, and the It is bent into. As described above, the adhesive force of the mortar to the coarse aggregate 1G can be further improved by making the cut 5x in the annular portion 5 and bending the cut. Further, since the cut 5x of the annular portion 5 can be formed and bent at the same time as the pressure bonding of the pair of flanged ball cutouts by pressing, the productivity of the coarse aggregate 1G does not decrease.

The coarse aggregate 1H shown in FIG. 10 has an outer shape substantially similar to that of the coarse aggregate 1C shown in FIGS. 5A and 5B, but as shown in FIG. 11, a small piece obtained by cutting a metal pipe into a predetermined length. The spherical portion 3 and the annular portion 5 are simultaneously molded by pressing 11 with the die 12. In this case, the diameter of the metal pipe is equal to or larger than the diameter of the spherical portion 3 of the coarse aggregate 1H. According to this coarse aggregate 1H, the step of joining the flanges 4 to each other can be omitted, and the productivity of the coarse aggregate can be improved. The outer shape of the annular portion 5 formed by pressing is not necessarily smooth, but in the present invention, the annular portion 5 does not have to be a clean annular shape, and may have a shape such that burrs are projected.

In the same manner, a coarse aggregate in which three or more spherical portions 3 are directly connected may be molded from a metal pipe, and three or more spherical portions are arranged side by side through the annular portion 5. You may be allowed to.

In place of the small piece 11 obtained by cutting the metal pipe, a small piece obtained by cutting a metal rod or a metal plate is hot-pressed with a similar die to obtain the same outer shape as the coarse aggregate obtained by press-molding the metal pipe. Can produce solid coarse aggregate. For example, a small piece 8 obtained by cutting a metal rod having a plate thickness equal to or larger than the diameter of a spherical portion is hot-pressed using a mold 9 as shown in FIG. 13 to produce the coarse aggregate 1I shown in FIG. Good. In this case, the diameter of the small piece 8 of the metal rod is equal to or larger than the diameter of the sphere of the spherical portion included in the shape of the coarse aggregate 1I, and the length of the small piece 8 is longer than two diameters of the spherical portion. The annular portion 5 is formed by pressing the small piece 8, but the annular portion 5 does not have to be a clean annular shape, and may have a shape such that burrs are projected. The coarse aggregate 1I has a large specific gravity due to being solidly formed, and is suitable as a coarse aggregate for heavy concrete.

In any of the above-described embodiments, the coarse aggregate of the present invention may have a wire protruding from the spherical portion in order to increase the bonding strength between the coarse aggregate and the mortar.

The coarse aggregate 1J shown in FIG. 14A is obtained by crimping the wire 13a between the pair of flanges 4 of the coarse aggregate 1A shown in FIG. 1A. As shown in FIG. 15, this coarse aggregate 1J is formed by press-forming a pair of flanged ball cutouts in which a flange 4 is continuously formed on the outer circumference of the bottom surface of the two ball cutouts 2, and they are opposed to each other. The wire 13a is sandwiched between the flanges 4 opposed to each other when the flanges 4 are pressed, the wire 13a is crimped to the flange 4, and the wire 13a penetrating the spherical portion 3 is projected from the annular portion 5. As the wire 13a, it is preferable to use a wire having a small diameter of 16 count or more and 21 count or less and easily curved, and it is particularly preferable to use a thin wire of 20 count or more. Even when the wire 13a is attached to the coarse aggregate main body composed of the spherical portion 3 and the annular portion 5 by crimping the wire 13a to the flange 4 by using the thin wire 13a, the coarse aggregate 1J after attachment is The wire 13a is easily curved during storage, transportation, preparation of ready-mixed concrete containing the coarse aggregate 1J, and the like, due to the force applied to the wire 13a. Therefore, even if the wire 13a and the coarse aggregate main body are not strictly fixed by welding or the like, it is sufficient that the wire 13a is crimped so as not to come off from the coarse aggregate main body. The cost can be reduced.

In addition, as shown in FIG. 14B in the stirring step of the fresh concrete after the production of the coarse aggregate having the wire by using the wire having a small diameter, the wire 13a is wound around the main body of the coarse aggregate, and the wound wire 13a is wound around the wire 13a. The mortar is captured, and the mortar and the coarse aggregate 1J move integrally. As a result, the substantial specific gravity of the coarse aggregate 1J approaches the mortar, so that the coarse aggregate 1J is less likely to settle in the fresh concrete, and the dispersibility is improved.

As shown in FIG. 17, the coarse aggregate to which the wire 13a is attached is manufactured by placing the wire 13a through a small piece 11 obtained by cutting a metal pipe into a predetermined length and pressing the small piece 11 through which the wire 13a is passed with a mold 12. You may. This makes it possible to more easily manufacture the coarse aggregate 1K shown in FIG. 16 that is substantially the same as the coarse aggregate 1J shown in FIG. 14A.

When attaching the wire to the coarse aggregate main body composed of the spherical portion 3 and the annular portion 5, the wire 13a penetrating the spherical portion 3 is projected from the spherical portion 3 as in the coarse aggregate 1L shown in FIG. May be. As a result, the wire can be attached to the coarse aggregate 1I shown in FIG. 12, which includes the solid spherical portion 3 and the annular portion 5.

Further, as in the coarse aggregate 1M shown in FIG. 19, the wire 13a may be wound around the coarse aggregate main body having the spherical portion 3 and the rectangular annular portion 5 from the outside of the coarse aggregate main body. The wire 13 a does not penetrate the spherical portion 3 and is not bonded to the spherical portion 3. When the wire 13a is wound around the main body of the coarse aggregate from the beginning, the mortar easily adheres to the coarse aggregate 1M from the beginning when the coarse aggregate 1M is mixed with the mortar, and the dispersibility of the coarse aggregate 1M in the mortar. To improve the strength of concrete. On the other hand, once the wire 13a is wound around the coarse aggregate main body, the wire 13a does not separate from the coarse aggregate main body during storage and transportation of the coarse aggregate 1M.

(Surface processing of coarse aggregate)
In order to improve the adhesion of concrete mortar to any of the above-described coarse aggregates 1A to 1M, surface roughness can be provided on the coarse aggregate by embossing, and a part or all of the surface, preferably Molten metal droplets generated by the spattering phenomenon of various weldings are welded to the entire surface, and the surface can be roughened by the metal particles welded to the surface. According to this method, as compared with the case where the surface of the coarse aggregate is simply irradiated with an electron beam to roughen the surface, the metal droplets generated by the melting of the electrode rod adhere to the surface of the coarse aggregate body, Since the wall thickness of the material main body is not reduced, the adhesiveness of the mortar to the coarse aggregate main body can be improved without lowering the strength of the coarse aggregate main body.

Among them, it is preferable to perform arc discharge using an electrode on the surface of the metal constituting the coarse aggregate, preferably to heat, and to cause molten metal droplets generated from the electrode to be deposited under heating. As a result, like the metal surface shown in FIG. 20, the entire surface of the coarse aggregate can be roughened by the deposit of molten metal droplets. Further, when arc discharge in which molten metal droplets are dropped from the electrodes is simultaneously performed on a plurality of coarse aggregates, the coarse aggregates may be joined by the molten metal droplets. For example, FIG. 21 shows that a coarse aggregate having two spherical portions 3 is manufactured by first press-molding a metal pipe, and then a plurality of coarse aggregates manufactured as described above are manufactured. It is a coarse aggregate 1N in which two coarse aggregates having two spherical portions are combined and welded together by performing arc discharge using an electrode rod at the same time. This coarse aggregate 1N has a shape in which two coarse aggregates are joined by welding in addition to the fact that the entire surface is roughened by a deposit of molten metal droplets. It becomes possible to further increase the tensile strength of the concrete as compared with the case where the deposit of molten metal droplets adheres to the surface without joining. Therefore, in the present invention, the metal coarse aggregates having the spherical portion and the annular portion protruding from the surface of the spherical portion so as to surround the outer periphery of the spherical portion are welded to each other, and molten metal droplets are deposited on the entire surface. A coarse aggregate aggregate for concrete is provided.

It should be noted that welding the molten metal droplets melted from the electrode rod to the surface of the coarse aggregate by arc discharge can be performed at high cost with high productivity.

Further, as described above, instead of performing arc discharge on the coarse aggregate and welding the molten metal droplets, the metal plate used during the production of the coarse aggregate, the metal pipe or the metal rod is previously subjected to arc discharge, etc. The molten metal droplets may be welded.

(Application example of coarse aggregate)
The coarse aggregate for concrete of the present invention can be substituted for a part or all of the coarse aggregate in the conventional concrete composition. As a preferred application example of the coarse aggregate for concrete of the present invention, in a concrete precast product, for example, using the hollow coarse aggregate of the present invention, it is possible to produce a lightweight reinforced concrete plate that is strong against compression and tension. .. Further, it can be preferably applied to a concrete structure that does not use reinforcing bars (for example, a dam wall, a road directly laid on the ground, a solid foundation of a building, a paved plaza, etc.) As a special application example, it can be preferably applied to a reinforced concrete floor slab of a highway installed at a position away from the ground. The coarse aggregate for concrete of the present invention, which is made of iron, particularly solid, is also useful as coarse aggregate of heavy concrete used for shielding radioactivity in nuclear facilities and the like. When the coarse aggregate for concrete of the present invention is made of a magnetic material, the panel can be attracted to the electromagnet to be transported, installed, and removed, and the workability is improved.

1A, 1A', 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, 1N Coarse aggregate 2 Ball lacking part 2g Bottom of ball missing part 3, 3a, 3b, 3c Ball-joined part, spherical part 4 Flange 5 Annular part 8 Small piece of metal rod 9 Mold 11 Small piece of metal pipe 12 Mold 13a Wire D Diameter of spherical part H Height of spherical part L Projection length of annular part La Extension line of the chord of the spherical part R Radius of the sphere of the ball lacking part t Thickness of the ball lacking part P Connection part W Width of coarse aggregate at the connection part

Claims (11)

A coarse aggregate for concrete made of metal having a plurality of spherical parts and an annular part protruding from the surface of the spherical part so as to surround the outer circumference of the plurality of spherical parts , wherein the plurality of spherical parts are directly connected to each other. The coarse aggregate for concrete, wherein the width of the coarse aggregate at the connecting portion between the spherical portions on the surface formed by the outer edge of the annular portion is not less than the minimum diameter of the diameters of the plurality of spherical portions. Concrete coarse aggregate according to claim 1 Symbol mounting spherical portion is hollow. Concrete coarse aggregate according to claim 1 Symbol mounting spherical portion is solid. The coarse aggregate for concrete according to any one of claims 1 to 4 , wherein metal particles formed by molten metal droplets are welded on the surface. The coarse aggregate for concrete according to claim 1 or 2, further comprising a flexible wire penetrating the spherical portion and protruding from the annular portion. Concrete coarse aggregate according to any one of claims 1 to 3, the spherical portion through a flexible wire that protrudes from the spherical portion. 2. The method for producing a metal coarse aggregate for concrete according to claim 1, wherein a press-formed metal plate forms a flanged ball cutout in which bottoms of the ball cutout are continuous with each other by a flange. A method of manufacturing coarse aggregate for concrete, in which the flanges of two flanged spheres are welded together. The method for producing a coarse aggregate for concrete made of metal according to claim 1, wherein the spherical aggregate and the annular portion are formed by pressing a metal rod or a metal pipe. It is a manufacturing method of the metal coarse aggregate for concrete of Claim 5 , Comprising: By press-working a metal plate, the bottom part of a ball cutout part forms the flanged ball cutout part which is continuous with a flange, and 2 A method for producing a coarse aggregate for concrete, wherein the bottoms of two flanged ball cutouts are opposed to each other via a flexible wire, and the opposed flanges are welded to each other. The method for producing a coarse aggregate for metal concrete according to claim 5 , wherein a flexible wire is passed through the metal pipe, and the spherical portion and the annular portion are formed by pressing the metal pipe through the wire. And a method for producing a coarse aggregate for concrete, in which the wire is projected from the annular portion. The method for producing a coarse aggregate for metal concrete according to claim 6, wherein a spherical portion and an annular portion are formed by pressing a metal rod or a metal pipe, and a through hole is formed in the spherical portion. A method for producing coarse aggregate for concrete through which a flexible wire is passed.