JP2021152462A - Measurement method and quality control method - Google Patents

Abstract

To measure an adhering amount of particles by a simple method.SOLUTION: A method for measuring an amount of particles 30 adhering to an anticorrosion steel material 10 having a steel material 11, a resin layer 20 that covers at least a part of the steel material 11, and the particles 30 that adhere to and are held to the resin layer 20, includes: a first step of immersing the steel material 11 in an organic solvent to dissolve the resin layer 20; a second step of filtering the particles from the solution by filtering the solution in which the resin layer 20 is dissolved using a filter paper 60; and a third step of measuring mass of the particles 30 filtered by the filter paper 60.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a measurement method and a quality control method, and more particularly to a technique suitable for measuring the amount of particles adhered and retained on a resin layer of an anticorrosion reinforcing bar and for quality control.

As an example of a reinforcing bar for concrete, a PVB resin containing polyvinyl butyral (hereinafter, PVB) as a main component is applied to the surface of a reinforcing bar bar, and particles (for example, silica sand, etc.) are attached to the PVB resin layer to prevent corrosion of the reinforcing bar (or). , Rust-proof reinforcing bar) has been put into practical use (see, for example, Patent Documents 1 and 2). The anticorrosion reinforcing bar can increase the adhesive strength with concrete by forming a large number of microprojections on the surface of the PVB resin layer with the silica sand attached to the PVB resin layer.

Japanese Unexamined Patent Publication No. 2017-043898 Japanese Unexamined Patent Publication No. 2011-147845

In the anticorrosion reinforcing bar, the amount of silica sand adhered to the PVB resin layer is important in order to obtain the desired adhesion performance and fixing performance to concrete. Therefore, it is desired to appropriately control the amount of silica sand adhered in the manufacturing process of the anticorrosion reinforcing bar.

In order to measure the amount of silica sand attached, a sample piece in which silica sand is attached to PVB resin coated on a reinforcing rod and a sample piece in which only PVB resin is coated on a reinforcing rod are prepared with substantially the same length. , It is conceivable that the difference in mass of each of these sample pieces is taken as the amount of silica sand adhered.

However, in such a measuring method, the total mass of each sample piece including the reinforcing bar having a mass heavier than that of silica sand is compared. Therefore, if there is even a slight difference in the length of each sample piece, the measurement error becomes large due to the influence of the mass difference of the reinforcing bar, and there is a problem that the amount of silica sand adhered cannot be appropriately grasped. Further, since it is necessary to separately prepare a sample piece coated only with PVB resin, which is different from the actual product, there is a problem that labor and labor are required.

The technique of the present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide a measuring method capable of accurately and effectively obtaining the amount of adhered particles by a simple method.

The measuring method of the present disclosure is a method for measuring the amount of adhered particles in an anticorrosion steel material having a steel material, a resin layer covering at least a part of the steel material, and particles adhering and being retained on the resin layer. The first step of immersing the anticorrosion steel material in an organic solvent to dissolve the resin layer, and the second step of filtering the dissolved liquid in which the resin layer is dissolved with a filter paper to filter the particles from the dissolved liquid. And a third step of measuring the mass of the particles filtered by the filter paper.

Further, before the second step, the filter paper before filtering the solution is dried, and the dry mass of the filter paper as a single unit is measured, and after the second step. Prior to the third step, the filter paper obtained by filtering the solution and the particles separated into the filter paper are dried and the total dry mass of the filter paper and the particles is measured. In the third step, it is preferable to calculate the amount of the particles adhered by subtracting the single dry mass from the measured total dry mass.

Further, the drying treatment is preferably carried out by heating at a temperature of 90 ° C. or higher for 30 minutes or longer.

Further, in the first step, it is preferable that the anticorrosion steel material is allowed to stand for 8 hours or more in a state of being immersed in the organic solvent.

Further, the steel material may be a reinforcing bar, the resin layer may be a resin layer containing polyvinyl butyral as a main component, and the particles may be silica sand.

Further, the organic solvent may be isopropyl alcohol.

The quality control method of the present disclosure is a quality control method of the anticorrosion steel material using the measurement method, and is described by comparing the mass of the particles measured in the third step with a predetermined reference value. It is characterized in that the fluctuation of the adhesion amount of the particles in the manufacturing process of the anticorrosion steel material is grasped.

According to the technique of the present disclosure, the amount of adhered particles can be accurately and effectively obtained by a simple method.

It is a schematic perspective view which shows an example of the reinforcing bar used for the anticorrosion reinforcing bar which concerns on this embodiment. It is a schematic radial sectional view which shows an example of the anticorrosion reinforcing bar which concerns on this embodiment. It is a flow figure explaining an example of the manufacturing method of the anticorrosion reinforcing bar which concerns on this embodiment. It is a flow figure explaining the flow of the measurement method which concerns on this embodiment. It is a schematic diagram explaining the measurement method which concerns on this Embodiment. It is a schematic diagram explaining the measurement method which concerns on this Embodiment. It is a schematic diagram explaining the measurement method which concerns on this Embodiment. It is a graph explaining an Example.

Hereinafter, the measurement method and the quality control method according to the present embodiment will be described with reference to the attached drawings.

[Anti-corrosion rebar / manufacturing method]
FIG. 1 is a schematic perspective view showing an example of a reinforcing bar rod 11 used for the anticorrosion reinforcing bar according to the present embodiment, and FIG. 2 is a schematic radial direction showing an example of the anticorrosion reinforcing bar 10 according to the present embodiment. It is a cross-sectional view.

As shown in FIG. 1, the reinforcing bar 11 surrounds a substantially columnar rod main body 12, at least one vertical rib 13 extending axially from the outer peripheral surface of the rod main body 12, and the outer peripheral surface of the rod main body 12. It is provided with a plurality of lateral ribs 14 extending in the direction and provided at predetermined intervals in the axial direction. The arrangement pattern of the vertical ribs 13 and the horizontal ribs 14 is not limited to the illustrated example, and may be another arrangement pattern. Further, the reinforcing bar 11 is not limited to the deformed reinforcing bar having ribs, and may be another reinforcing bar such as a round bar.

As shown in FIG. 2, the anticorrosion reinforcing bar 10 of the present embodiment forms a PVB resin layer 20 containing PVB resin as a main component on the outer peripheral surface of the reinforcing bar rod 11, and silica sand 30 as particles is formed on the PVB resin layer 20. Manufactured by adhering and retaining.

Here, as shown in FIG. 3, the anticorrosion reinforcing bar 10 includes (1) a first step of blasting the surface of the reinforcing bar 11 and (2) a second step of heating the reinforcing bar 11 with a high-frequency heating device. , (3) A third step of applying a powder containing PVB resin as a main component to the surface of the reinforcing rod 11 by electrostatic powder coating, and (4) adhesion of silica sand to the reinforcing rod 11 in which the PVB resin layer 20 is melted. It is produced by sequentially performing a fourth step of causing the resin layer to be formed and a fifth step of (5) cooling and solidifying the molten PVB resin layer 20. The method for producing the anticorrosion reinforcing bar 10 is not limited to this, and it can also be produced by another method. For example, it is possible to switch the order of the second step and the third step.

[Measurement method]
FIG. 4 is a flow chart for explaining the flow of the measurement method according to the present embodiment.

As shown in FIG. 4, the measurement methods of the present embodiment include (1) step S10 for preparing a measurement sample, (2) step S20 for measuring the length of the measurement sample, and (3) measurement sample. S30 (first step of the present disclosure) in which the resin layer is dissolved by immersing the filter paper in an organic solvent and allowing it to stand, and (4) a step of drying the filter paper and measuring the dry mass of the filter paper as a single unit. S40 and (5) a step S50 (second step of the present disclosure) for filtering silica sand by injecting a solution into a filter paper and filtering, and (6) drying treatment of the filter paper and silica sand are carried out. Step S60 to measure the total dry mass of filter paper and silica sand, and (7) the step to convert the mass of silica sand obtained by subtracting the dry mass of a single unit from the total dry mass into the ^{amount of adhesion per 1 m 2 of the outer peripheral surface of the anticorrosion reinforcing bar 10.} It is carried out by performing S70 (third step of the present disclosure) in order. Hereinafter, the details of each step S10 to S70 will be specifically described.

(Preparation of measurement sample: step S10)
In step S10, measurement samples (preferably a plurality of reinforcing bars) are prepared by cutting the anticorrosion reinforcing bars in which silica sand is adhered and held on the PVB resin layer to a predetermined length. As the reinforcing bar as the base material, each reinforcing bar with the names specified in Table 4 of JIS G 3122: 2010 can be used. The cutting method is not particularly limited, but from the viewpoint of preventing heat melting of the PVB resin layer, it is desirable to select a cutting method that does not generate heat (or suppresses heat generation) on the cut surface. Examples of the cutting method that does not generate heat include a mode of cutting with a band saw or the like.

The axial length of the measurement sample is not particularly limited, but the maximum length is preferably set to fit in the container in consideration of the capacity (height) of the container used in step S30 described later. Further, in the case of a deformed reinforcing bar as shown in FIG. 1, if the measurement sample is made too short, the ribs 13 and 14 (particularly the lateral rib 14) are easily affected. From this point of view, the minimum length of the measurement sample is preferably an appropriate length including a plurality of lateral ribs 14.

(Measurement of measurement sample length: step S20)
In step S20, as shown in FIG. 5, the axial length L of the measurement sample S prepared in step S10 described above is measured. The axial length L is preferably measured in units of 0.01 mm using a caliper (for example, a micrometer). Here, the cut surfaces formed at both ends of the measurement sample S may not be perpendicular to the axial direction, and the accuracy may not be guaranteed by measuring only one point. From this point of view, the axial length L measures the lengths L1 and L2 of at least two points orthogonal to the radial direction, and the average value (L = (L1 + L2) / 2) of these is measured in the axial direction of the measurement sample S. The length is preferably L.

It is also possible to perform step S20 using the reinforcing bar 11 in a state where the PVB resin is dissolved and removed after the completion of step S50 described later.

(Dissolution of resin layer: step S30)
In step S30, as shown in FIG. 6, the measurement sample S is put into the container 50, and the organic solvent is injected until the measurement sample S is completely immersed. When the organic solvent is injected, the opening of the container 50 is closed and sealed by the cap 51 to prevent evaporation and dissipation of the organic solvent. When the container 50 is sealed, it is stored in a stable temperature environment such as a room until the PVB resin layer of the measurement sample S is completely dissolved.

Here, the type of the organic solvent is not particularly limited as long as it is a solvent capable of melting the PVB resin, but from the viewpoint of resin solubility and ease of handling, it is preferable to use alcohol, particularly isopropyl alcohol (isopropanol). The concentration of alcohol may be adjusted as appropriate, but the purity is preferably 98% by mass or more. The temperature at which it is allowed to stand may be room temperature (for example, about 23 ° C.). The time for static storage is not particularly limited, but when isopropyl alcohol is used, it is preferably at least 4 hours or more, and more preferably 12 hours or more. The upper limit of the time is not particularly limited, but when it is used for quality control of a production line, it is preferably within 24 hours. Examples of the solvent capable of melting the PVB resin include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, diacetone alcohol, benzyl alcohol, and 1-methoxy-2-propanol for glycols. For 3-methoxy-1-butanol, carbitol, ethers, diosakin, THF, for cellosolves, methyl cellosolve, ethyl cellosolve, butyl cellosolve, for esters, methoxypropyl acetate, ethyl butyrate, glycolic acid. In the case of n-butyl ester, DBE, and ketones, methyl ethyl ketone (MEK) and cyclohexanone can be used.

In the illustrated example, the measurement sample S is put into the container 50 in the vertical direction, but it may be put in the container 50 in the horizontal direction depending on the shape of the container 50. When the sample S is loaded sideways, both ends of the measurement sample S may be supported by supporting means and suspended in an organic solvent.

(Drying of filter paper, measurement of dry mass: step S40)
In step S40, the filter paper is put into a drying facility such as a drying furnace or an electric furnace, and the mass of the filtered paper after drying (hereinafter, referred to as a single drying mass mA) is measured. The drying treatment of the filter paper is preferably carried out until the mass loss is less than about 0.01 g. At this time, it is desirable that the drying temperature is 90 ° C. or higher and the drying time is 30 minutes or longer. It is not necessary to start the step S40 after the end of the step S30, and the step S40 may be performed in parallel with the step S30 before the end of the step S30.

(Filtration of solution, filtration of silica sand: step S50)
As shown in FIG. 7, in step S50, the filter paper 60 is set in the filter device 61 (for example, a funnel), and the solution in which the PVB resin is dissolved is filtered by the filter paper 60 to filter the silica sand from the solution. .. At this time, if only the container 50 is tilted, the silica sand settled on the bottom side of the container 50 and the silica sand adhering to the surface of the measurement sample S may remain on them, and the remaining silica sand may not be recovered by the filter paper 60. .. In order to reliably recover such residual silica sand, it is preferable to wash the container 50 and the measurement sample S with a cleaning liquid, and inject the cleaning liquid into the filter paper 60.

Here, when distilled water is used as the cleaning liquid, the PVB resin in the dissolution liquid solidifies again and the silica sand cannot be filtered out. Therefore, it is preferable to use the same solvent (isopropyl alcohol in this embodiment) as the organic solvent used in step S30 described above as the cleaning liquid.

(Drying treatment of filter paper and silica sand, measurement of dry mass: step S60)
In step S60, the filter paper and the silica sand collected on the filter paper are put into a drying furnace or a drying facility such as an electric furnace, and the total mass of the filter paper and the silica sand after drying (hereinafter referred to as total drying mass mB) is measured. The drying treatment of the filter paper and the silica sand is preferably carried out until the mass loss is less than about 0.01 g. At this time, it is desirable that the heating temperature is 90 ° C. or higher and the drying time is 30 minutes or longer.

(Mass calculation and conversion of silica sand: step S70)
In step S70, the mass m of the silica sand adhering to the measurement sample S is calculated according to the following mathematical formula (1) in which the single dry mass mA acquired in step S40 is subtracted from the total dry mass mB acquired in step S60. ..
m = mB-mA ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (1)
However, m: Mass of silica sand (g)
mA: Single dry mass (g)
mB: Total dry mass (g)

Next, the mass m of the obtained silica sand is converted into the amount of adhesion M per ^{1 m 2} of the outer peripheral surface of the anticorrosion reinforcing bar 10 according to the following mathematical formula (2).
M = α × Ms ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2)
However, M: Adhesion amount of silica sand per ^{1 m 2 (g)}
α: Conversion coefficient per ^{1 m 2}
α = 1 / D
D: Total area of the outer peripheral surface of the measurement sample S (m ² )
D = d × L
d: Nominal circumference (m) of the reinforcing bar of the measurement sample
L: Axial length (m) of the measurement sample
Ms: Total mass of filtered silica sand (g)
Ms = Σm

According to the measurement method of the present embodiment described in detail above, the anticorrosion reinforcing bar 10 manufactured on an actual production line or the like is cut to a predetermined length to prepare a measurement sample S, and the prepared measurement sample is prepared. The PVB resin layer 20 is dissolved by immersing S in an organic solvent, the silica sand 30 is filtered by filtering the solution with a filter paper 60, and the PVB resin layer is measured by measuring the mass of the filtered silica sand 30. The amount of the silica sand 30 attached and retained on the 20 can be obtained by a simple method. As a result, in the production line of the anticorrosion steel material 10, the fluctuation of the adhesion amount of the silica sand 30 can be grasped by appropriately comparing the measured adhesion amount of the silica sand 30 with the predetermined control reference value, and the quality control can be performed. It becomes possible to improve (quality control method).

In addition, compared to the method of comparing the actual measurement sample S with the separately prepared sample coated only with PVB resin, the influence of the heavy reinforcing bar 11 can be effectively eliminated, and the measurement accuracy is assured. It becomes possible to improve. Further, since it is not necessary to separately prepare a sample coated only with the PVB resin, it is possible to effectively reduce labor and labor.

Next, a specific embodiment according to the measurement method of the present embodiment will be described. The present disclosure is not limited to the following examples.

In the example, a plurality of measurement samples having an axial length of about 50 mm were prepared using anticorrosion reinforcing bars in which No. 8 silica sand was attached to the PVB resin layer. No. 8 silica sand has, for example, a particle size distribution in which particles having a particle size of less than 0.15 mm and a particle size of 0.05 mm or more occupy 70% or more. As the reinforcing bar which is the base material of these measurement samples, D16 (nominal circumference: 5.0 cm) specified in JIS G 3112: 2010 (steel bar for reinforced concrete) was used.

Each measurement sample was prepared by cutting the anticorrosion reinforcing bar with a band saw. The axial length L of each test sample is measured by measuring the lengths L1 and L2 of two points orthogonal to the radial direction with a micrometer by the method described in step S20 above, and the average value (L = (L1 + L2)) of these. Obtained by calculating / 2). Isopropyl alcohol (2-propanol) was used as the organic solvent for dissolving the PVB resin layer. Isopropyl alcohol has a purity of 98% or more. As the filter paper for filtering the silica sand, a filter paper having a grain size sufficiently smaller than the minimum particle size of the No. 8 silica sand was used. A drying furnace for drying the filter paper was used in which the heating temperature could be set to 90 ° C. or higher.

[Drying time]
The time required for the drying treatment described in step S60 described above (drying time) was examined. In this test, a total of five measurement samples # 1 to # 5 were prepared, and their axial lengths L were measured. Each measurement sample # 1 to # 5 was immersed in isopropyl alcohol and allowed to stand for about 12 hours. For the filter paper from which the silica sand was filtered out from the measurement samples # 1 to # 5, the dry mass of a single substance before filtration and the total dry mass after filtration were measured. The drying treatment was carried out by setting the heating temperature of the drying furnace to about 105 ° C. The total dry mass was measured as appropriate according to the passage of the drying time, and the mass change was recorded. The results of this test are shown in Table 1 below. Further, FIG. 8 shows a graph of the drying time from 0 minute to 2 hours in Table 1.

As is clear from Table 1 and FIG. 8, it was found that the mass change of the total dry mass became stable when the drying time reached 30 minutes in all the samples # 1 to # 5. From this result, it was confirmed that the drying time in step S60 described above should be about 30 minutes to 1 hour.

[Standing storage time (dissolution time)]
The time (dissolution time) required for the static storage described in step S30 described above was examined. In this test, a total of 50 measurement samples # 1 to # 50 were prepared, and their axial lengths L were measured. Each of the measurement samples # 1 to # 50 was immersed in isopropyl alcohol and stored standing for a predetermined time. Specifically, samples # 1 to # 10 are about 2 hours, samples # 11 to # 20 are about 4 hours, samples # 21 to # 30 are about 8 hours, samples # 31 to # 40 are about 12 hours, and samples. Each of # 41 to # 50 was left to stand for about 18 hours. For these statically stored samples # 1 to # 50, the solution was filtered through a filter paper, and the mass of the filtered silica sand was measured. The results of this test are shown in Tables 2-6 below.

As is clear from Tables 2 to 6, the amount of silica sand adhered calculated for each dissolution time was found to be stable after the total and average dissolution times reached 8 hours. From this result, it was confirmed that the dissolution time in step S30 described above is preferably 8 hours or more, and 12 hours is sufficient.

The present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, in the above embodiment, the anticorrosion reinforcing bar 10 in which the reinforcing bar 11 is coated with PVB resin has been described, but the resin layer may be a resin layer other than PVB, and the particles are particles other than silica sand. May be good. Further, the application of the present disclosure is not limited to the anticorrosion reinforcing bar 10 using the reinforcing bar 11 as the base material, and can be widely applied to the anticorrosion steel material using the steel material as the base material.

10 Corrosion-proof reinforcing bars (corrosion-proof steel materials)
11 Reinforcing bar (steel material)
20 PVB resin layer (resin layer)
30 Quartz sand (particles)
50 containers 60 filter paper

Claims (7)

A method for measuring the amount of adhered particles in an anticorrosion steel material having a steel material, a resin layer covering at least a part of the steel material, and particles adhering and being held on the resin layer.
The first step of immersing the anticorrosion steel material in an organic solvent to dissolve the resin layer, and
A second step of filtering the particles from the solution by filtering the solution in which the resin layer is dissolved with a filter paper.
A measuring method comprising a third step of measuring the mass of the particles filtered by the filter paper. Prior to the second step, the filter paper before filtering the solution is dried, and the dry mass of the filter paper is measured.
After the second step and before the third step, the filter paper obtained by filtering the solution and the particles separated into the filter paper are dried, and the total amount of the filter paper and the particles is processed. Further including, with the step of measuring the dry mass,
The measurement method according to claim 1, wherein in the third step, the amount of adhered particles is calculated by subtracting the single dry mass from the measured total dry mass. The measuring method according to claim 2, wherein the drying treatment is performed by heating at a temperature of 90 ° C. or higher for 30 minutes or longer. The measurement method according to any one of claims 1 to 3, wherein in the first step, the anticorrosion steel material is allowed to stand for 8 hours or more in a state of being immersed in the organic solvent. The measuring method according to any one of claims 1 to 4, wherein the steel material is a reinforcing bar, the resin layer is a resin layer containing polyvinyl butyral as a main component, and the particles are silica sand. The measuring method according to any one of claims 1 to 5, wherein the organic solvent is isopropyl alcohol. A quality control method for an anticorrosion steel material using the measurement method according to any one of claims 1 to 6.
A quality control method characterized by grasping fluctuations in the amount of adhesion of the particles in the manufacturing process of the anticorrosion steel material by comparing the mass of the particles measured in the third step with a predetermined reference value.

Images