Cement adhesion inhibitor

Abstract

To provide, for example, a cement adhesion inhibitor capable of inhibiting fresh concrete from adhering to an inner surface of a hopper of a concrete pump vehicle.SOLUTION: A cement adhesion inhibitor according to the present application is made by adding a cellulose nanofiber. When applied to an inner surface of a concrete hopper of a concrete pump vehicle, for example, the inhibitor can inhibit cement sticking. The cement adhesion inhibitor is mainly composed of calcium carbonate. The calcium carbonate is the one recovered in whole or in part from a ready-mixed concrete sludge. The amount of cellulose nanofibers added is 0.5 wt.% or more. A retardants are added.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cement adhesion inhibitor, and more particularly to an inhibitor that effectively inhibits cement adhesion by using cellulose nanofiber (CNF). [Background technology]

[0002] A concrete pump truck has the following general configuration: First, there is the vehicle body, and a concrete hopper is mounted at the rear end of this vehicle body. A concrete pump is mounted in front of the concrete hopper. A pumping tube is attached to the concrete pump in a compressible manner. One end of the pumping tube is connected to the concrete hopper, and the other end is connected to the concrete transport pipe.

[0003] Ready-mix concrete is poured into the concrete hopper. By driving the concrete pump and compressing the pumping tube, the ready-mix concrete in the concrete hopper is pumped to a designated location via the pumping tube and concrete transport pipe.

[0004] Incidentally, there was a problem in that the fresh concrete would harden on the inner surface of the concrete hopper mentioned above. As solutions to this problem, for example, there are Patent Documents 1, 2, and 3.

[0005] First, the lubricating oil composition described in Patent Document 1 is a release oil containing animal fats and / or vegetable fats and a nonionic surfactant of polyoxyethylene sorbitic acid fatty acid esters, characterized in that the release oil is an asphalt mixture adhesion inhibitor composition or a concrete release agent composition.

[0006] Next, the cement adhesion inhibitor for metal surfaces described in Patent Document 2 is characterized by having a polyhydroxycarboxylic acid ester.

[0007] Furthermore, the cement adhesion inhibitor described in Patent Document 3 comprises a condensation retarder and a thickener, and uses at least one of a cellulose derivative-based thickener and a natural polysaccharide-based thickener as the thickener. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 4205585 [Patent Document 2] Patent No. 3140565 [Patent Document 3] Patent No. 6571826 [Overview of the project] [Problems that the invention aims to solve]

[0009] While the conventional configuration described above provides some degree of adhesion suppression, it is by no means sufficient, and further performance improvements were required.

[0010] The present invention is based on these points and aims to provide a cement adhesion inhibitor that can suppress, for example, the adhesion of fresh concrete to the inner surface of a concrete pump truck hopper. [Means for solving the problem]

[0011] In order to solve the above problems, the cement adhesion inhibitor according to claim 1 of the present invention is It mainly consists of calcium carbonate, and is a heber sludge. Cellulose nanofibers The mixture contains 0.5 to 1.1% by weight of the above, and 0.05 to 0.1% by weight of a retarder which is at least one of ascorbic acid, erythorbic acid, polycarboxylic acid, Rochelle acid, or corsorbic acid. It is applied to the inner surface of the concrete hopper of a concrete pump truck. It is characterized by the following: Furthermore, the cement adhesion inhibitor according to claim 2 is the cement adhesion inhibitor according to claim 1, The above calcium carbonate is, in whole or in part, calcium carbonate recovered from ready-mix concrete sludge. It is characterized by the following: [Effects of the Invention]

[0012] As described above, the cement adhesion inhibitor according to claim 1 of the present invention has a structure in which cellulose nanofibers are added, so when applied to the inner surface of the concrete hopper of a concrete pump truck, for example, cement adhesion can be suppressed. Furthermore, the cement adhesion inhibitor according to claim 2 is a cement adhesion inhibitor according to claim 1, in which case calcium carbonate is the main component, thereby enhancing the above effect. Furthermore, according to the cement adhesion inhibitor of claim 3, in the cement adhesion inhibitor of claim 1 or claim 2, all or part of the calcium carbonate is recovered calcium carbonate from ready-mix concrete sludge, which enhances the above effect and promotes the effective utilization of waste. Furthermore, according to the cement adhesion inhibitor of claim 4, the amount of cellulose nanofiber added is 0.5% by weight or more in the cement adhesion inhibitor described in any of claims 1 to 3, so the above effect can be made more reliable. Furthermore, according to the cement adhesion inhibitor of claim 5, a retarder is added to the cement adhesion inhibitor described in any of claims 1 to 4, making the above effect more reliable. Furthermore, according to the cement adhesion inhibitor of claim 6, in the cement adhesion inhibitor of claim 5, the retarder is at least one of ascorbic acid, erythorbic acid, polycarboxylic acid, Rochelle acid, and corsorbic acid, which makes the above effect more reliable. Furthermore, according to the cement adhesion inhibitor of claim 7, since the amount of retarder added in the cement adhesion inhibitor of claim 6 is 0.05% by weight or more, the above effect can be made more reliable. Furthermore, the cement adhesion inhibitor according to claim 8 is characterized in that, as described in any of claims 1 to 7, it is applied to the inner surface of the concrete hopper of a concrete pump truck. [Brief explanation of the drawing]

[0013] [Figure 1] This is a side view of a concrete pump truck, showing one embodiment of the present invention. [Figure 2] This is a plan view of a concrete pump truck, showing one embodiment of the present invention. [Figure 3] This is a flow chart showing the process of manufacturing recovered calcium carbonate from raw sludge generated in a raw concrete factory, showing one embodiment of the present invention. [Figure 4] This is a photograph inside the soncrete hopper showing the effects, showing one embodiment of the present invention. [Figure 5] This is a photograph inside the concrete hopper showing a comparative example.

Embodiments for Carrying out the Invention

[0014] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. First, the configuration of the concrete pump truck 1 is, for example, as described in Japanese Utility Model Laid-Open No. 61-31936. As shown in FIGS. 1 and 2, there is a vehicle body 3, and this vehicle body 3 is provided with a chassis 5. A driver's seat 7 is installed at the front end of this chassis 5. Further, a concrete hopper 9 is installed at the rear end of the chassis 5.

[0015] A concrete pump 11 is installed on the side of the chassis 5 beside the concrete hopper 9. A pumping tube 13 is installed on the concrete pump 11, and one end of this pumping tube 13 is connected to the concrete discharge port of the concrete hopper 9. A concrete transport pipe 15 is connected to the other end of the pumping tube 13.

[0016] A boom 17 is installed on the chassis 5 in a retractable manner, and this boom 17 is composed of a first arm 19, a second arm 21, and a third arm 23. The concrete transport pipe 15 extends to the base of the third arm 23. As shown in Figure 2, another concrete transport pipe 25 is extended from the base of the third arm 23 to the tip of the third arm 23. And yet another concrete transport pipe 25 is extended from the tip of the third arm 23.

[0017] By extending the boom 17, the concrete transport pipe 25 is raised to the desired height, and ready-mix concrete is poured from its tip.

[0018] A water tank 31 and an oil tank 33 are installed on top of the chassis 5, along with a control panel 35.

[0019] The inner surface of the concrete hopper 9 is coated with a cement adhesion inhibitor 41. This cement adhesion inhibitor 41 is made by adding calcium carbonate (CaCO3), cellulose nanofibers, paper sludge, and a retarder to water.

[0020] First, the calcium carbonate mentioned above is composed of porous calcium carbonate, hydrotalcite-containing porous calcium carbonate, and precipitated calcium carbonate. The porous calcium carbonate described above is obtained, for example, by processing ready-mix concrete sludge generated from ready-mix concrete plants to adjust particle size and composition. Because the edges of the particles of this porous calcium carbonate are rounded, it has a lubricating effect (bearing effect), and because it is porous, it has high water absorption performance, which contributes to the fluidity of the cement adhesion inhibitor 41 itself. Furthermore, the concrete sludge mentioned above refers to the residue obtained after recovering aggregate from sludge water generated during processes such as cleaning concrete mixer trucks or truck agitator drums, as well as from returned concrete and leftover concrete.

[0021] The above-mentioned hydrotalcite-containing porous calcium carbonate is also, for example, obtained by processing raw sludge generated from a ready-mixed concrete plant to adjust the particle size and composition, and is a fine powder with a high powder degree and composed only of hydrotalcite and calcite. This hydrotalcite-containing porous calcium carbonate has the same effect as clay minerals, and in the cement fixing inhibitor 41 in this embodiment, it plays a role in adjusting clay and also contributes to suppressing material separation. The above-mentioned hydrotalcite has the general formula [M 2+ · 1-x M 3+ · x (OH)2][A n- · x / n ·mH2O], and is one of the compounds represented thereby. M 2+ represents a divalent metal ion, M 3+ represents a trivalent metal ion, A n- · x / n represents an interlayer anion, respectively. Also, 0 < x < 1, n is the valence of A, and 0 ≤ m ≤ 1.

[0022] The above-mentioned porous calcium carbonate and the above-mentioned hydrotalcite-containing porous calcium carbonate are produced, for example, by the "Method and Apparatus for Recovering Useful Granular Substances from Waste" described in Japanese Patent No. 4501098. FIG. 3 is a schematic system diagram showing the general configuration of the recovery apparatus described in Japanese Patent No. 4501098. First, the sludge-like waste 51 generated in the ready-mixed concrete plant is introduced into the precipitation apparatus 53 to precipitate the raw sludge. Next, the precipitated raw sludge is taken out and introduced into the dehydration apparatus 55, and dehydration treatment is performed until the water content becomes 60% or less. Next, the dehydrated sludge is taken out and dried (naturally dried or mechanically dried) until the water content becomes 25% or less, and then introduced into the pulverization apparatus 57 and pulverized until the particle size becomes 30 mm or less.

[0023] Next, the pulverized dried sludge is introduced into the cyclone 61 by the charging device 59, and the particle size is 250 μm or the specific surface area is 4000 cm 2The material is finely ground until it reaches a concentration of 1 / g or more (air-permeable Blaine assay). The resulting finely ground particles are then collected by a collection device 63. The collection device 63 is equipped with two stages of bag filters 65 and 67. The first bag filter 65 collects the porous calcium carbonate, and the second bag filter 67 collects the hydrotalcite-containing porous calcium carbonate. These porous calcium carbonate and hydrotalcite-containing porous calcium carbonate are then dropped and collected onto a belt conveyor 69.

[0024] The above-mentioned precipitated calcium carbonate is synthetic calcium carbonate, which is a fine powder calcium carbonate whose particle shape has been made uniform through chemical treatment. Because this precipitated calcium carbonate has a uniform particle shape, when forming the lubricating layer 43 with the cement adhesion inhibitor 41, it has the effect of making the surface of the lubricating layer 43 uniform and smooth.

[0025] The cellulose nanofibers described above are cellulose fibers, and are materials whose fiber width has been refined to the nano-order, less than a few hundredths of a micrometer. They are generally obtained in large quantities from wood. These cellulose nanofibers have several characteristics, including being lightweight and strong, having ultrafine fibers, a large specific surface area, minimal dimensional change due to heat, high gas barrier properties, exhibiting characteristic viscosity in water, and being environmentally friendly.

[0026] The cellulose nanofibers spread in a matrix within the cement adhesion inhibitor 41, preventing the sedimentation of fine particles that are denser than water, and imparting thixotropy (the property of a fluid whose viscosity decreases when a certain pressure is applied and returns to its original state after a certain period of time) to the cement adhesion inhibitor 41. This prevents the cement adhesion inhibitor 41 from clumping together in the concrete hopper 9, and because it flows when force is applied, it has the effect of adapting to the transport speed. Furthermore, even if insufficiently washed cement paste solidified material remains in the concrete hopper 9, there is a concern that a large amount of moisture in the cement adhesion inhibitor 41 will be drawn out by the cement paste solidified material and cause blockage. However, in the case of the cement adhesion inhibitor 41 according to this embodiment, the addition of cellulose nanofibers prevents excessive adhesion of the cement adhesion inhibitor 41 to the inner surface of the concrete hopper 9, thus preventing blockage.

[0027] The aforementioned paper sludge specifically consists of micro-sized cellulose fibers derived from paper sludge, and in the cement adhesion inhibitor 41, it contributes to the separation of materials from the fresh concrete.

[0028] Possible examples of the above-mentioned retarding agents include ascorbic acid, erythorbic acid, polycarboxylic acid, Rochelle acid, and corsorbic acid.

[0029] In the case of Example 1 in this embodiment, the component ratios are as follows. (Example 1) Water: 10.750 kg Calcium carbonate derived from ready-mix concrete sludge: 2,500 kg Precipitated calcium carbonate: 2,500 kg Paper sludge: 2.250 kg Cellulose nanofiber: 0.200 kg Sodium erythorbate: 0.015 kg In this Example 1, 1.0% by weight of cellulose nanofibers is added, as shown in formula (1). 0.200kg / 18.2150kg≒0.011---(I) It is desirable that cellulose nanofibers be added in an amount of 0.5% by weight or more. Furthermore, as shown in formula (II), 0.1% by weight of sodium erythorbate is added. 0.015kg / 18.2150kg≒0.001---(II) It is desirable that 0.05% by weight or more of sodium erythorbate is added.

[0030] In Example 1, the cellulose nanofiber used is "Binfis®," a biomass nanofiber manufactured by Sugino Machine Co., Ltd. This biomass nanofiber is produced by processing cellulose, chitin, chitosan, and carboxymethylcellulose (CMC) using ultra-high pressure water jet technology. The cellulose nanofiber used in Example 1 is produced by processing cellulose using ultra-high pressure water jet technology and is an extremely fine fiber with a diameter of 20 nm and a length of several micrometers.

[0031] According to this embodiment, the following effects can be achieved. In other words, since the cement hardening inhibitor 41 is applied to the inner surface of the concrete hopper 9, the hardening of cement on the inner surface of the concrete hopper 9 can be suppressed.

[0032] The above effects will be explained with reference to Figures 4 and 5. Figure 4 is a photograph showing the inner surface of the concrete hopper 9 when the cement adhesion inhibitor 41 according to this embodiment is applied, and Figure 5 is a photograph showing the inner surface of the concrete hopper 9 when a conventional oil-based adhesion inhibitor is applied. In the photograph in Figure 5, the cement is clearly fixed, whereas in the photograph shown in Figure 4, the cement's fixation is barely visible. In the case shown in Figure 4, cellulose nanofibers are added to the cement adhesion inhibitor 41, giving it thixotropic properties. As a result, there is no dripping of the applied cement adhesion inhibitor 41, and the concrete does not accumulate in the concrete hopper 9. Therefore, the impact on the fresh concrete is minimal. Furthermore, a drying film is formed, providing a high level of adhesion prevention. In contrast, as shown in Figure 5, a conventional oil-based anti-adhesion agent 41' is applied, but because it is not thixotropic, the applied oil-based anti-adhesion agent 41' accumulates at the bottom of the concrete hopper 9, resulting in a low anti-adhesion effect. Furthermore, it mixes with the fresh concrete, affecting the quality of the fresh concrete.

[0033] Furthermore, the present invention is not limited to the above-described embodiment. First, in the above embodiment, an example of the amounts of each component constituting the cement adhesion inhibitor was shown as Example 1, but the invention is not limited to that. Furthermore, there are no particular limitations on the amount of cellulose nanofiber added. Furthermore, regarding the manufacturing method of cellulose nanofibers, in addition to the underwater counter-impact method of "Binfis®," various cellulose nanofibers produced by physical treatments such as the grinder method and ball mill method, and chemical treatments such as the catalytic oxidation method of TEMPO can also be used. Furthermore, in the above-described embodiment, a portion of the calcium carbonate was recovered from sludge, but the invention is not limited to this, and it is also conceivable to use only recovered sludge calcium carbonate. Furthermore, it is also possible that sludge recovery calcium carbonate will not be used. Furthermore, in the case of the above-described embodiment, sludge-recovered calcium carbonate was obtained by processing muddy waste from a ready-mix concrete plant, but the invention is not limited to this, and other types of muddy waste may also be processed. Furthermore, although the inner circumferential surface of the concrete hopper of a concrete pump truck was used as an example in the above-described embodiment, the application location is not particularly limited. [Industrial applicability]

[0034] The present invention relates to a cement adhesion inhibitor, and more particularly to an agent that effectively inhibits cement adhesion by using cellulose nanofibers. For example, it is suitable for use when applied to the inner surface of a concrete hopper in a concrete pump truck to inhibit cement adhesion. [Explanation of Symbols]

[0035] 1. Concrete pump truck 9. Concrete hopper 41. Cement adhesion inhibitor 43 Lubricating layer

Claims

1. A product comprising calcium carbonate as the main component, 0.5 to 1.1% by weight of heber sludge and cellulose nanofiber, and 0.05 to 0.1% by weight of a retarder which is at least one of ascorbic acid, erythorbic acid, polycarboxylic acid, Rochelle acid, and corsorbic acid, A cement adhesion inhibitor characterized by being applied to the inner surface of the concrete hopper of a concrete pump truck.

2. A cement adhesion inhibitor according to claim 1, characterized in that all or part of the calcium carbonate is calcium carbonate recovered from ready-mix concrete sludge.

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