Method for forming resin film on artificial lightweight aggregate

Abstract

To provide a method of efficiently coating a lightweight aggregate with a resin at a low cost.SOLUTION: A method includes spraying a light-curing resin onto artificial lightweight aggregate while conveying the artificial lightweight aggregate on a conveyor, and irradiating the light-curing resin sprayed onto the artificial lightweight aggregate with ultraviolet rays while conveying the artificial lightweight aggregate on the conveyor. The light-curing resin may be selected from epoxy-based resins, acrylic-based resins, polysiloxane-based resins, fluorine-based resins, and polyimide-based resins.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] One embodiment of the present invention relates to a method for treating lightweight aggregates such as artificial lightweight aggregates.

Background Art

[0002] Concrete is mainly formed by mixing cement, fine aggregates, coarse aggregates, lightweight aggregates, water, and admixtures to produce ready-mixed concrete and then curing it. Due to its excellent mechanical properties, weather resistance, ease of handling, and economy, concrete is widely used in various fields as one of the important structural materials for creating the social production infrastructure and economic infrastructure.

[0003] By using lightweight aggregates as aggregates, the weight of concrete can be reduced. Therefore, concrete containing lightweight aggregates can be used as a structural material for high-rise buildings and the like. Lightweight aggregates can be classified into artificial lightweight aggregates, natural lightweight aggregates, and by-product lightweight aggregates. Among them, artificial lightweight aggregates are widely spread. Artificial lightweight aggregates mainly use expanded shale, expanded clay, expanded slate, fly ash, etc. as raw materials and have a large number of fine pores on the surface and inside. For this reason, when adjusting ready-mixed concrete containing lightweight aggregates, it is known to coat the lightweight aggregates with resin so as not to absorb excessive water contained in the ready-mixed concrete (see Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] One embodiment of the present invention aims to provide a new method for controlling and reducing the water absorption rate by coating lightweight aggregate with resin. Alternatively, one embodiment of the present invention aims to provide a method for efficiently and low-costly coating lightweight aggregate with resin.

Means for Solving the Problems

[0006] One embodiment of the present invention is a method for reducing the water absorption characteristics of artificial lightweight aggregate. This method includes spraying a photocurable resin onto the artificial lightweight aggregate while transporting the artificial lightweight aggregate on a conveyor, and irradiating ultraviolet rays onto the photocurable resin sprayed onto the artificial lightweight aggregate while transporting the artificial lightweight aggregate on the conveyor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0008] Hereinafter, each embodiment of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in various modes without departing from the gist thereof, and is not to be construed as being limited to the description of the embodiments exemplified below.

[0009] The drawings may be schematically represented in terms of the width, thickness, shape, etc. of each part compared to the actual embodiment for clearer explanation, but this is merely an example and does not limit the interpretation of the present invention.

[0010] Hereinafter, a method for controlling and reducing the water absorption characteristics of artificial lightweight aggregates according to one embodiment of the present invention will be described. A flowchart of this method is shown in FIG. 1. As shown in FIG. 1, first, lightweight aggregates are produced. Specifically, expanded perlite, expanded vermiculite, expanded shale, expanded clay, expanded slate, expanded fly ash, expanded bauxite, or expanded slag, etc. are used as raw materials, and the raw materials are heated in a heating furnace such as a rotary kiln or a vertical furnace. The heating temperature depends on the raw materials as well, but for example, it may be selected from the range of 800°C to 1300°C. Crushing may be performed before or after heating the raw materials. Due to the heat treatment, the gas present in the raw materials is desorbed, and as a result, a large number of pores are generated on the surface and inside of the obtained artificial lightweight aggregates.

[0011] Subsequently, a photocurable resin is sprayed onto the artificial lightweight aggregates, and the photocurable resin is applied to all or part of its surface. Here, the spraying of the photocurable resin is performed while transporting the artificial lightweight aggregates. For example, as shown in FIG. 2, the artificial lightweight aggregates 120 are put into the hopper 100 and placed on the conveyor 102. The conveyor 102 may be, for example, a belt conveyor including a pair of pulleys 106 and a belt 104 wound around them, or may be a screw conveyor (not shown). The artificial lightweight aggregates 120 placed on the conveyor 102 are transported at a constant speed and transported to the light-shielded area 130.

[0012] The light-shielded area 130 may be configured so that light absorbed by the photocurable resin, for example, ultraviolet light in the range of 200 nm to 400 nm, is not irradiated inside. For example, the light-shielded area 130 may be a space covered with an acrylic plate mixed with a dye or pigment that absorbs the above ultraviolet light.

[0013] Subsequently, within the light-shielding area 130, while transporting the artificial lightweight aggregate 120 by the belt 104, the photocurable resin 110 is sprayed from the nozzle 108. As the photocurable resin 110, an acrylic resin, an epoxy resin, a polyimide resin, a polysiloxane resin, a fluorine resin, or the like can be used. The photocurable resin 110 may contain an initiator that reacts with ultraviolet light, or may have a side chain having a photoreactive substituent. A supply source of the photocurable resin 110 (not shown) is connected to the nozzle 108, and the photocurable resin 110 is supplied to the nozzle 108 by a pump (not shown). At this time, a solvent may be supplied simultaneously to adjust the viscosity of the photocurable resin 110. Alternatively, air may be supplied simultaneously, and the photocurable resin 110 may be sprayed by a spraying method. By this operation, the photocurable resin 110 is applied to all or part of the surface of the artificial lightweight aggregate 120.

[0014] Within the light-shielding area 130, an irradiation device 112 equipped with a light source 114 is arranged. As the light source 114, a Xe short-arc lamp, a high-pressure mercury lamp, a halogen lamp, a deuterium lamp, or the like can be used. Alternatively, a laser light source such as a KrCl excimer laser or a KrF excimer laser may be used. When using a laser light source, the emitted light may be adjusted by an optical element and deformed into laser light having a linear irradiation surface.

[0015] The photocurable resin 110 applied to the surface of the artificial lightweight aggregate 120 is crosslinked and cured by the light from the light source 114, forming a resin film. As a result, at least a part of the pores of the artificial lightweight aggregate 120 is covered by the resin film. Since the water absorption of the artificial lightweight aggregate 120 is caused by water entering the pores, the absorption rate of the artificial lightweight aggregate 120 can be reduced by forming the resin film. In addition, since the thickness and area of the film can be controlled by adjusting the transport speed of the belt 104, the amount and concentration of the photocurable resin 110 sprayed, it is also possible to control the absorption rate of the artificial lightweight aggregate 120.

[0016] As an arbitrary configuration, air may be blown onto the artificial lightweight aggregate (hereinafter referred to as resin-coated artificial lightweight aggregate) 122 on which a resin film is formed, using a blower 116. By blowing air, the solvent remaining from the resin-coated artificial lightweight aggregate 122 or the uncured photocurable resin 110 can be removed. Alternatively, as shown in FIG. 3, the blower 116 may be disposed within the light-shielded area 130. In this case, before irradiating the photocurable resin 110 on the surface of the artificial lightweight aggregate 120 with light from the light source 114, an air blowing process may be performed on the photocurable resin 110. Thereby, the remaining solvent and the excess photocurable resin 110 can be removed, and the photocurable resin 110 adhering to the belt 104 can be removed. As a result, the frequency of maintenance for removing the cured photocurable resin 110 from the conveyor 102 can be reduced, which contributes to a reduction in the manufacturing cost of the resin-coated artificial lightweight aggregate 122.

[0017] In order to prevent or suppress the adhesion of the photocurable resin 110 to the belt 104, a plurality of through holes 104a may be provided in the belt 104 (FIGS. 4(A) and 4(B)). The shape of the through holes 104a may be arbitrarily set, and may be circular or substantially circular as shown in FIG. 4(A), or may be a quadrilateral formed by a plurality of linear frames 104b (FIG. 4(B)). The size of the through holes 104a is preferably such that the artificial lightweight aggregate 120 does not pass through, and the maximum length L of the through holes 104a (the maximum length in the plane formed by the belt 104) is preferably 1 mm or more and 5 mm or less, or 1 mm or more and less than 5 mm. By providing a plurality of through holes 104a, the uncured photocurable resin 110 that adheres to the belt 104 without adhering to the surface of the artificial lightweight aggregate 120 can be removed, so that the cured photocurable resin 110 can be prevented from accumulating on the belt 104. Although not shown, a container for recovering the uncured photocurable resin 110 that has fallen from the belt 104 may be provided under the conveyor 102. After filtering the recovered uncured photocurable resin 110 with a filter, it may be sprayed again from the nozzle 108 onto the artificial lightweight aggregate 120.

[0018] By applying the embodiments of the present invention, a resin coating can be efficiently and inexpensively formed on the surface of artificial lightweight aggregate. Therefore, the water absorption rate of the obtained resin-coated artificial lightweight aggregate 122 can be easily controlled. Accordingly, when preparing ready-mixed concrete, it is possible to avoid a large amount of water being absorbed, increasing the viscosity and causing an increase in the pressure required for transportation, and at the same time, appropriately adjust the properties of the concrete obtained after curing.

[0019] As described above, each of the embodiments described as embodiments of the present invention can be implemented in appropriate combination as long as they do not contradict each other. Based on each embodiment, those in which those skilled in the art appropriately add, delete, or change the design of the components are also included in the scope of the present invention as long as they have the gist of the present invention.

[0020] Even for other effects different from the effects brought about by the above-described embodiments, those that are obvious from the description of this specification or can be easily predicted by those skilled in the art are naturally understood to be brought about by the present invention.

Description of Reference Numerals

[0021] 100: Hopper, 102: Conveyor, 104: Belt, 104a: Through-hole, 104b: Frame, 106: Pulley, 108: Nozzle, 110: Photo-curable resin, 112: Irradiation device, 114: Light source, 116: Blower, 120: Artificial lightweight aggregate, 122: Resin-coated artificial lightweight aggregate, 130: Light-shielding area

Claims

1. A first step of spraying a photocurable resin onto the artificial lightweight aggregate while transporting the artificial lightweight aggregate by a conveyor, and a second step of irradiating ultraviolet rays to the photocurable resin sprayed on the artificial lightweight aggregate while transporting the artificial lightweight aggregate by the conveyor to cure the photocurable resin and form a resin film on the artificial lightweight aggregate, wherein the conveyor is an integral conveyor that continuously performs the first step and the second step, a method for forming a resin film on an artificial lightweight aggregate.

2. The method for forming a resin film according to Claim 1, wherein the conveyor includes a belt in which a plurality of through holes are formed.

3. The method for forming a resin film according to Claim 2, wherein the maximum length of the through holes is 5 mm or less.

4. The method for forming a resin film according to Claim 1, wherein the photocurable resin is selected from an epoxy resin, an acrylic resin, a polysiloxane resin, a fluorine-containing resin, and a polyimide resin.

5. The method for forming a resin film according to Claim 1, further comprising blowing air onto the artificial lightweight aggregate after spraying the photocurable resin.

6. The method for forming a resin film according to Claim 1, further comprising recovering a part of the sprayed photocurable resin and spraying it again onto the artificial lightweight aggregate.

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