JP4889022B2 - Method for separating components of fresh concrete or fresh mortar and method for recovering fibers mixed in fresh concrete or fresh mortar - Google Patents

Description

  The present invention relates to a method for separating components of fresh concrete or fresh mortar, and also relates to a method for recovering fibers mixed in fresh concrete or fresh mortar.

In order to prevent delamination and flaking of concrete, to suppress crack growth, and to reinforce concrete, fiber is mixed into fresh concrete and the concrete is placed. Steel fibers are widely used as the fibers, and non-steel fibers such as vinylon fibers and polypropylene fibers are also used. In order for the fiber reinforced concrete to exhibit the predetermined performance as described above, it is necessary that a predetermined amount of fibers be mixed in the concrete. Therefore, there is a need for a method for confirming whether a specified amount of fibers in fresh concrete are mixed before placing. At present, there are several methods for confirming the amount of fiber in fresh concrete. For example, “JCI-SF7: Test method for fiber mixing rate of fiber reinforced concrete” in JCI Standards Collection (edited by Japan Concrete Institute) and concrete standard specifications (Publisher: Japan Society of Civil Engineers) “JSCE-F 554-1999: Steel fiber reinforced concrete steel fiber mixing rate test method”. However, in these standards, only “separate and collect fibers while washing the sample with water” is described, and no specific equipment or procedure for separating fibers is stated. There is no current situation. For example, the work of separating a sample by hand washing with water takes a lot of time and labor, and is difficult to apply in an actual test. For concrete mixed with steel fibers, a method has been proposed in which steel fibers are separated and collected from fresh concrete and the collected steel fibers are weighed (see, for example, Patent Document 1). However, this method can be applied only to fibers having a higher specific gravity than water, and cannot be applied to fibers having a small specific gravity (1.0 or less) such as polypropylene fibers.
JP 2004-20217 A

  In the conventional method, it took time to separate and collect the fibers from the fresh concrete. Therefore, an object of the present invention is to enable separation and collection of fibers and the like from fresh concrete in a short time.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that fresh concrete or fresh mortar is introduced into the liquid, the liquid is stirred while generating microbubbles in the liquid, and then the liquid is allowed to stand. The method for separating the components of fresh concrete or fresh mortar, wherein the fresh concrete or fresh mortar is separated into a sediment submerged in the bottom of the liquid and a levitated matter floating on the surface of the liquid.

  According to a second aspect of the present invention, fresh concrete or fresh mortar mixed with fibers having a specific gravity smaller than that of the liquid is added to the liquid, and the liquid is stirred after the liquid is stirred while generating microbubbles. And separating the fresh concrete or fresh mortar into a sediment submerged in the bottom of the liquid and fibers floated on the surface of the liquid. .

  According to a third aspect of the invention, fresh concrete or fresh mortar mixed with magnetic fibers having a specific gravity greater than that of the liquid is added to the liquid, and the liquid is stirred after the liquid is stirred while generating microbubbles. In the fresh concrete or fresh mortar characterized by separating the fresh concrete or fresh mortar from the fresh concrete or the sediment settled at the bottom of the liquid by allowing to stand, and collecting the magnetic fiber from the precipitate by a magnet. This is a method for collecting mixed fibers.

  Note that fresh concrete refers to concrete that has not yet solidified, and fresh mortar refers to mortar that has not yet solidified.

  According to the invention according to claim 1, by generating microbubbles in the liquid, the microbubbles adhere to each component of fresh concrete or fresh mortar, and the fresh concrete or fresh mortar is easily separated for each component. Takes less time. Of the components of fresh concrete or fresh mortar, those having a specific gravity greater than that of the liquid precipitate, and those having a specific gravity smaller than that of the liquid float. Therefore, the components of fresh concrete or fresh mortar can be separated in a short time.

  According to the second aspect of the invention, by generating microbubbles in the liquid, the microbubbles adhere to each component of fresh concrete or fresh mortar, and the fresh concrete or fresh mortar is easily separated for each component. Then, among the components of fresh concrete or fresh mortar, aggregate having a specific gravity greater than that of the liquid is precipitated, and fibers having a specific gravity smaller than that of the liquid are levitated. In this case, since the microbubbles are attached to the fiber, the fiber rises faster. Therefore, the components of fresh concrete or fresh mortar can be separated in a short time.

  According to the third aspect of the invention, by generating microbubbles in the liquid, the microbubbles adhere to each component of fresh concrete or fresh mortar, and the fresh concrete or fresh mortar is easily separated for each component. And a magnetic body fiber precipitates with an aggregate, and a magnetic body fiber adheres to a magnet among precipitates. Therefore, it is possible to separate and recover the magnetic fiber from fresh concrete or fresh mortar easily and in a short time.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for implementing the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

(1) Apparatus to be used FIG. 1 is a schematic cross-sectional view showing a separation apparatus 1 used for component analysis of fresh concrete.

  As shown in FIG. 1, the separation device 1 includes a liquid tank 2, a microbubble generator 3, a pipe 4, and a gas supply unit 5. The top of the liquid tank 2 is open. When using the separation apparatus 1, the liquid 6 is stored in the liquid tank 2. The liquid 6 stored in the liquid tank 2 is water, and the water may be pure water or tap water. The liquid 6 may be oil without using water, or may be another type of liquid.

  Inside the liquid tank 2, a microbubble generator 3 is disposed and attached. The microbubble generating unit 3 is provided in a tubular shape, and a plurality of microinjecting ports 31 are formed on the outer peripheral surface thereof, and these microinjecting ports 31 lead to the hollow interior of the microbubble generating unit 3.

  The end of the microbubble generator 3 is connected to one end of the pipe 4, and the other end of the pipe 4 is connected to the gas supply unit 5. The gas supply unit 5 sends gas to the microbubble generation unit 3 through the pipe 4. Specifically, the gas supply unit 5 is an air pump that sucks ambient air and sends the sucked air to the micro-bubble generating unit 3, or sucks ambient air and compresses the sucked air in a compressed state. It is an air compressor that sends out to the bubble generation unit 3 or a gas cylinder that stores gas in a compressed state and sends the compressed air to the microbubble generation unit 3. When the gas supply unit 5 is a gas cylinder, the gas stored in the gas supply unit 5 may be air or other gas (for example, inert gas (nitrogen gas, carbon dioxide gas, helium gas, argon gas). Etc.)).

  When the gas is sent into the microbubble generator 3, the gas is ejected from each micro injection port 31 of the microbubble generator 3, and the microbubble 61 is generated in the liquid 6. The generated microbubbles 61 are microbubbles or micronanobubbles, and the diameter of the microbubbles 61 is preferably 50 μm or less.

(2) Method for separating components of fresh concrete and analysis method thereof Hereinafter, a method for separating components of fresh concrete using the separation device 1 and an analysis method thereof will be described. Fresh concrete means fresh concrete containing aggregate, water, cement, admixture and the like. Moreover, fresh means the state which has not yet solidified.

  First, the volume and weight of fresh concrete to be analyzed are measured. When a fresh concrete air amount measurement tester is used, since the volume is known, the labor of volume measurement can be saved.

Subsequently, the liquid 6 is stored in the liquid tank 2 of the separation device 1.
Subsequently, when a gas is supplied to the microbubble generator 3 by the gas supply unit 5, microbubbles 61 are generated from the microinjection ports 31 of the microbubble generator 3, and the microbubbles 61 are dispersed in the liquid 6.

  Subsequently, the fresh concrete whose volume and weight are measured is put into the liquid 6 in the liquid tank 2. The liquid 6 is agitated while the microbubbles 61 are generated from the microbubble generator 3 by the gas supply unit 5. Thereby, fresh concrete isolate | separates for every component. In particular, since microbubbles adhere to each component (aggregate, etc.) of fresh concrete, their separation is accelerated.

  Subsequently, the gas supply unit 5 is stopped and the liquid 6 is left in the liquid tank 2. Thereby, among the components of the fresh concrete, those having a specific gravity smaller than that of the liquid 6 float on the water surface of the liquid 6, and those having a specific gravity larger than the liquid 6 are deposited on the bottom of the liquid tank 2. Subsequently, the floating substance floating on the water surface of the liquid 6 is collected with a fine mesh, and the floating substance is dried naturally or with a dryer. After collecting the levitated matter, the liquid 6 is poured out and the precipitate is collected. Here, among the components of the fresh concrete, the cement flows together with the liquid 6. Then, the weight and volume content of the levitated matter is determined by measuring the weight and volume of the levitated material collected, and the weight content and volume content of the precipitate are determined by measuring the weight and volume content of the collected levitated material. Ask.

As described above, according to the present embodiment, by generating the microbubbles 61 in the liquid 6, the microbubbles adhere to each composition of the fresh concrete, and the fresh concrete is easily separated for each component, which is necessary for the separation. Time is shortened. Therefore, it is possible to separate the components of fresh concrete in a short time.
In addition, the production investment of the separation device 1 itself is inexpensive.
In the above, the analysis object / sorting object is fresh concrete, but fresh mortar containing fine aggregate, cement and the like may be the analysis object / sorting object.

The case where polypropylene fiber having a specific gravity smaller than that of water (specific gravity 0.91) is mixed in fresh concrete will be described more specifically.
First, the volume and weight of fresh concrete mixed with fiber are measured.
Water is stored in the liquid tank 2 as the liquid 6, and microbubbles 61 are generated in the liquid 6 by the gas supply unit 5. Subsequently, the fiber-mixed fresh concrete is poured into the liquid 6 in the liquid tank 2, and the liquid 6 is agitated while the gas supply unit 5 generates the microbubbles 61 from the microbubble generator 3. Next, when the gas supply unit 5 is stopped and the liquid 6 is allowed to stand in the liquid tank 2, polypropylene fibers having a specific gravity smaller than that of the water float up on the water surface, and aggregates settle on the bottom. Subsequently, the polypropylene fibers floating on the water surface of the liquid 6 are collected with a fine mesh, and the polypropylene fibers are dried naturally or with a dryer. And the weight of the collect | recovered polypropylene fiber is measured and a fiber mixing rate (%) is calculated | required by following Formula (1).
V _f = W _f / (V × ρ _f ) × 100 (1)
here,
V _f : Fiber mixing rate (%)
W _f : Weight of fresh concrete measured (g)
V: Volume of fresh concrete measured (cm ³ )
ρ _f : unit volume weight (specific gravity) of the measured fiber

  In addition, if it is a fiber whose specific gravity is smaller than the liquid 6 instead of a polypropylene fiber, you may obtain | require a fiber mixing rate similarly. Similarly, for fresh mortar mixed with fibers (for example, polypropylene) having a specific gravity smaller than that of the liquid 6, the components may be similarly separated to obtain the fiber mixing rate.

The case where the steel fiber (specific gravity 7.85) whose specific gravity is larger than water is mixed in fresh concrete is demonstrated more concretely.
Similarly to the case of Example 1, the volume and weight of the fiber-mixed fresh concrete are measured, and the microbubbles 61 are generated from the microbubble generator 3 to the liquid 6 (the liquid 6 is water) by the gas supply unit 5. Then, the fiber-mixed fresh concrete is put into the liquid 6 and the liquid 6 is stirred. And if the gas supply part 5 is stopped | fastened and the liquid 6 is left still, a steel fiber and aggregate will settle to the bottom. When the liquid 6 is poured out, a precipitate remains. Next, when a magnet such as an electromagnet is brought close to the precipitate, the steel fibers adhere to the magnet in the precipitate, and the steel fibers can be separated and recovered from the precipitate. Note that the steel fibers may be picked up from the precipitate visually.
And after collect | recovering the collected steel fiber, the weight of the collect | recovered steel fiber is measured and a fiber mixing rate (%) is calculated | required by Formula (1).
In addition, although the steel fiber was mentioned as an example as a magnetic body fiber, even when other magnetic body fibers are mixed in fresh concrete, the magnetic body fibers are similarly separated and recovered, and the fiber mixing rate of the magnetic body fibers is determined. You may ask. Similarly, for fresh mortar mixed with magnetic fiber (for example, steel fiber) having a specific gravity greater than that of liquid 6, the magnetic fiber may be separated and recovered to obtain the fiber mixing rate.

Nonmagnetic fiber (vinylon fiber (specific gravity 1.3), polyethylene terephthalate fiber (specific gravity 1.3), glass fiber (specific gravity 1.70), aramid fiber (specific gravity 1.28)) having a higher specific gravity than water is fresh. The case where it is mixed in concrete will be described more specifically.
Similarly to the case of Example 1, the volume and weight of the fiber-mixed fresh concrete are measured, and the microbubbles 61 are generated from the microbubble generator 3 to the liquid 6 (the liquid 6 is water) by the gas supply unit 5. Then, the fiber-mixed fresh concrete is put into the liquid 6 and the liquid 6 is stirred. And if the gas supply part 5 is stopped | fastened and the liquid 6 is left still, a nonmagnetic body fiber and aggregate will settle to the bottom. When the liquid 6 is poured out, a precipitate remains. Next, the non-magnetic fiber is picked up from the precipitate visually.
And the weight of the collect | recovered nonmagnetic material fiber is measured, and a fiber mixing rate (%) is calculated | required by Formula (1).
For fresh mortar mixed with non-magnetic fiber (for example, vinylon fiber, polyethylene terephthalate fiber, glass fiber, aramid fiber) having a specific gravity greater than that of liquid 6, the non-magnetic fiber is recovered and the fiber mixing rate You may ask for.

The case of fresh concrete in which fibers are not mixed will be described more specifically.
As in the case of Example 1, the volume and weight of fresh concrete are measured, and the microbubbles 61 are generated from the microbubble generator 3 by the gas supply unit 5 into the liquid 6 (the liquid 6 is water). Fresh concrete is put into the liquid 6 and the liquid 6 is stirred. And if the gas supply part 5 is stopped | fastened and the liquid 6 is left still, aggregate will settle to the bottom. When the liquid 6 is poured out, the aggregate remains and the aggregate can be recovered. Then, the collected aggregate is screened and classified for each particle size, and the weight content of the aggregate is obtained by measuring the weight of each aggregate. Further, the volume content is obtained by dividing the measured weight of the aggregate by the unit volume mass of the aggregate.
In addition, about fresh mortar which is not mixed with the fiber, the components may be similarly separated, and the weight content and volume content may be obtained for each particle size of the aggregate.

It is a device used for component analysis of fresh concrete.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Separator 2 Liquid tank 3 Microbubble generation part 5 Gas supply part 6 Liquid 61 Microbubble

Claims (3)

  A fresh concrete or fresh mortar is added to the liquid, and the liquid is agitated while generating microbubbles in the liquid, and then the liquid is allowed to stand to settle the fresh concrete or fresh mortar on the bottom of the liquid. The method of fractionating the components of fresh concrete or fresh mortar, characterized in that the product is separated into an object and a levitated substance floating on the surface of the liquid.   A fresh concrete or a fresh mortar mixed with fibers having a specific gravity smaller than that of the liquid is added to the liquid, and the liquid is allowed to stand after stirring the liquid while generating fine bubbles in the liquid. A method for fractionating fresh concrete or fresh mortar components, wherein the fresh mortar is fractionated into precipitates that sink to the bottom of the liquid and fibers that float on the surface of the liquid.   The fresh concrete or fresh mortar mixed with magnetic fibers having a specific gravity greater than that of the liquid is added to the liquid, and the liquid is stirred after the liquid is stirred while generating microbubbles in the liquid. A method for recovering fibers mixed in fresh concrete or fresh mortar, comprising separating a concrete or fresh mortar into a sediment that sinks to the bottom of the liquid, and recovering magnetic fibers from the precipitate by a magnet.

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