KR20200013504A - Discoloration indicator for Cement Inspection and inspection method using the same - Google Patents

Abstract

The present invention is a test method of inspecting whether it is cement or material other than the cement before the cement is moved to a storage silo after cement is brought into the scene, and can prevent an accident in which the material is mis-injected into a cement silo if it is determined to be the material other than the cement according to inspection results. The present invention relates to a composition for an indicator discolored by a pH difference, and a test method using the same. A discoloration indicator according to the present invention is a mixture of a discoloration reagent prepared by dissolving 0.1 to 10 wt% of phenolphthalein and others in ethanol or the like and an acidic solution prepared by mixing 0.1 to 10 vol% of hydrochloric acid (HCl) and others with water, wherein the discoloration indicator is prepared by mixing the discoloration reagent with the acidic solution at a volume ratio of 1:0.1-1:10. The cement is discolored within a predetermined time, and the material other than the cement is not discolored when mixing and stirring the discoloration indicator developed in the present invention with cement. Therefore, the method can determining whether it is cement or not in a rapid and simple manner on the spot.

Description

Discoloration indicator for Cement Inspection and inspection method using the same}

The present invention relates to a discoloration indicator and a cement inspection method using the same, and more specifically, using an indicator discolored by a pH difference, and quickly determining whether it is cement or a material other than cement from the time of discoloration by mixing with cement powder. It is a possible test method, and relates to a composition of an indicator discolored by a pH difference and a test method using the same. At this time, the cement is a cement corresponding to KS L 5201 (Portland cement), KS L 5210 (blast furnace slag cement), KS L 5211 (fly ash cement).

The cement is pulverized by adding a certain amount of setting gypsum for adjusting the setting time to a clinker obtained by mixing limestone, clay, silica, iron material and the like and baking at about 1,450 ° C. The main compounds of cement are tricalcium silicate (3CaO · SiO ₂ ), dicalcium silicate (2CaO · SiO ₂ ), tricalcium aluminate (3CaO · Al ₂ O ₃ ), tetracalcium iron aluminate (4CaO · Al ₂ O ₃ · Fe ₂ O ₃ ), and when reacted with water, tricalcium silicate and dicalcium silicate are formed of calcium silicate hydrate (nCaO · SiO ₂ · mH ₂ O) and calcium hydroxide (Ca (OH) ₂ ), Intensity is expressed.

At this time, because of the resulting cured cement pore water calcium hydroxide hydroxide ions (OH ^-) in a concentration of high pH As it is to be expressed more than 11, and serves to prevent corrosion in a reinforced concrete structure. The calcium hydroxide reacts with carbon dioxide (CO ₂ ) in the air over time to change to calcium carbonate (Ca (CO ₃ )), and loses alkalinity, which is called carbonation.

When the concrete structure is carbonated and loses its alkalinity, the passivation film around the reinforcing bar is destroyed, which promotes reinforcing steel corrosion. To evaluate the rate of carbonation progress, KS F 2596 (Concrete Carbonation Depth Determination Method) is followed, and the concrete is evaluated by spraying 1% indicator of phenolphthalein on the concrete. Phenolphthalein indicators are characterized by discoloration in red at pH 8-10. By spraying the phenolphthalein solution on the concrete, the red discolored portion can be evaluated as the uncarbonated portion and the red discolored portion.

Most patents in the field of construction using discoloration indicators such as phenolphthalein are in the concrete field. Korean Patent No. 1005641020000 (2006.03.20) relates to a method of using a variety of indicators and comprehensively calculate the carbonation depth more accurately. Domestic registered patents 1017471920000 (2017.06.08), 1017099550000 (2017.02.20), 1016764900000 (2016.11.09) refer to a test apparatus that can measure the carbonation depth while taking concrete specimens. Domestic registered patent 1018480670000 (2018.04.05) relates to a method for quantitatively calculating the area where the concrete is carbonated.

There is no patent registered as a method for testing cement powders using indicators that discolor with pH, such as phenolphthalein. Cement is used as a variety of construction materials such as ready-mixed concrete, concrete secondary products, solidified materials, injection materials, etc. When cement is brought to the site and transferred to a storage silo, it is necessary to confirm whether it is cement or a non-cement material. This is because fly ash and blast furnace slag fine powders other than cement can be misinjected into cement storage silos. The blast furnace slag powder has a white color and can be distinguished from cement by the naked eye. However, fly ash has a color similar to that of cement and cannot be distinguished by the naked eye. Therefore, there is a need for an inspection method that can quickly determine whether cement is used to prevent misinjection of materials other than cement into cement silos.

(1) KR 10-0564102 B (2) KR 10-1747192 B (3) KR 10-1709955 B (4) KR 10-1676490 B (5) KR 10-1848067 B

An object of the present invention is to provide a discoloration indicator and test method for testing cement powder in order to meet the above requirements.

In addition, an object of the present invention is to provide a test method capable of determining whether a cement or a material other than cement is discolored within a predetermined time with respect to a small amount of cement powder brought into the field.

It is also an object of the present invention to provide a discoloration indicator composition that does not discolor in response to free CaO (free CaO) components contained in materials other than cement.

In order to achieve the above technical problem, the present invention, phenolphthalein (Phenolphthalein), thymolphthalein (Thymolphthalein), nitramine (Nitramine) and trinitrobenzene (Trinitrobenzene) at least one selected from the group 0.1 to 10% by weight of ethanol Ethanol, Benzene, Hexane, Chloroform, Ether, Dichloromethane, Tetrahydrofuran, Tetrahydrofuran, Ethyl acetate, Methanol, Iso Discoloration reagent dissolved in propyl alcohol (Isopropyl alcohol), water, dimethyl sulfoxide, dimethylformamide, acetonitrile; And hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (mP ₂ O ₅ nH ₂ O), carbonic acid (H ₂ CO ₃ ) and acetic acid (C ₂ H ₄ O ₂ ) At least one selected from the group consisting of 0.1 ~ 10% by volume of a mixed solution of the acid solution with water, the discoloring reagent and the acid solution is a cement discoloration indicator, characterized in that mixed in a volume ratio of 1: 0.1 ~ 1:10 to provide.

In addition, the present invention provides a cement test method for determining whether or not cement according to the color change by mixing the color change indicator described above with a sample.

According to the present invention, by utilizing the properties of the indicator discolored by the pH difference, by varying the ratio of the indicator composition so as not to react with materials other than cement, by reacting with the cement powder discolored from cement or other materials other than cement Provide a test method that can determine cognition

The present invention is basically a test method for checking whether cement is a material other than cement before it is brought to the site and transferred to a storage silo, and when it is determined that the material is other than cement, it is possible to prevent misinput into the cement silo. have. Fly ash, which is often used as admixture with cement, is indistinguishable from cement. Fly ash may contain some free CaO component. In this case, the pH is increased so that the 1% solution of phenolphthalein, which is generally used for measuring concrete carbonation depth, is discolored in the same color as cement and is indistinguishable. In order to solve this problem, it is possible to appropriately mix the discoloration reagent and the acidic solution so that the discoloration indicator does not react with the free CaO component of the fly ash, but can be adjusted to react only with cement.

Figure 1 is a photograph of the discoloration results of the sample by the phenolphthalein 1% solution.
Figure 2 is a photograph showing the test method of the discoloration indicator reagent developed using phenolphthalein as the discoloration reagent.
3 is a photograph showing an example in which the discoloration state of the fly ash and cement is changed using the same discoloration indicator.

Hereinafter, preferred embodiments of the present invention will be described in detail.

Conventional discoloration indicators, such as 1% solution of phenolphthalein, react to fly ash containing free CaO as well as cement. Thus, the 1% solution of phenolphthalein is discolored equally in cement and fly ash (including free CaO), making it impossible to distinguish between the two materials.

In KS L 5405 (Fly Ash), the free Ca content of 1 to 4 fly ashes is 2.5% or less. The free CaO component reacts with water to produce calcium hydroxide, at which time the pH of the solution rises as the hydroxide ions elute, and the phenolphthalein 1% solution discolors in response.

Table 1 is a table showing the chemical components constituting the cement, fly ash 1 and fly ash 2 samples.

division Chemical composition (%, by XRF) SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ K ₂ O Na ₂ O LOI Free CaO cement 19.32 5.81 2.84 61.82 3.76 2.54 0.84 0.204 2.82 1.23 Fly Ash 1 53.7 25.2 5.63 4.51 1.97 0.34 1.13 0.39 4.03 0 Fly Ash 2 50.7 17.3 7.87 10.1 3.49 2.03 1.41 1.70 3.17 2.10

The color change when reacting 3 ml of the conventional phenolphthalein 1% solution used for measuring the concrete carbonation depth with 15 g of the sample of Table 1 is shown in FIG. The test was carried out on two types of fly ash with different cement and free CaO content (Fly ash 1 contains 0% of free CaO and fly ash 2 contains 2.1% of free CaO).

In FIG. 1, (a) is a powder state, (b) is a photograph taken after 1 minute of reaction, and (c) is 5 minutes of reaction, in order of cement, fly ash 1, and fly ash 2 from the left.

The color of fly ash and cement varies depending on the production area, and it can be seen that the powders are difficult to distinguish with each other.

After one minute of reaction with a 1% solution of phenolphthalein, fly ash 2, which is high in cement and free CaO, begins to turn red. After 5 minutes, cement and fly ash 2 turn red and cannot be distinguished, and fly ash 1 having a low free CaO component has no color change. Each powder reacts with water contained in a 1% solution of phenolphthalein to produce calcium hydroxide, and as the hydroxide ions are eluted, the pH rises to red. The rate of pH rise is related to the amount of calcium hydroxide produced in each material and the rate at which the hydroxide ions are eluted.

As described above, the phenolphthalein 1% solution used in the conventional concrete carbonation test cannot distinguish between cement and fly ash containing free CaO.

The present invention is to solve this problem by considering the amount of calcium hydroxide and the hydroxide ion dissolution rate generated in the fly ash free CaO KS standard of 2.5% or less, neutralizing it with an appropriate ratio of acid solution.

To this end, the present invention is 0.1 to 10% by weight of at least one selected from the group consisting of phenolphthalein (Phenolphthalein), thymolphthalein (Thymolphthalein), nitramine (Nitramine) and trinitrobenzene (Ethanol), benzene (Benzene), Hexane, Chloroform, Ether, Dichloromethane, Tetrahydrofuran, Tetrahydrofuran, Ethyl acetate, Methanol, Isopropyl alcohol ), A discoloration reagent dissolved in water, dimethyl sulfoxide, dimethylformamide, and acetonitrile; And hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (mP ₂ O ₅ nH ₂ O), carbonic acid (H ₂ CO ₃ ) and acetic acid (C ₂ H ₄ O ₂ ) At least one selected from the group consisting of 0.1 to 10% by volume of a mixture of acidic solution mixed with water,

The discoloration reagent and the acidic solution provides a cement discoloration indicator, characterized in that the mixture in 1: 0.1 ~ 1:10 volume ratio.

(Example 1)

The change of discoloration time according to the acid concentration of the acid solution in the cement discoloration indicator of the present invention was measured.

As a discoloration reagent, a 1% by weight solution of phenolphthalein was used, and an HCl 0 to 6% by volume solution was used. The discoloring reagent and the acid solution were mixed at a mixing ratio (volume ratio) of 1: 1. At this time, the change of color change time was measured using 15 ml of color change indicators mixed with 5 g of cement or fly ash samples.

Table 2 below shows the discoloration time according to the acid solution content ratio of the cement discoloration indicator of the present invention. In Table 2, fly ash 3 to 5 are samples prepared by separately adding free CaO to fly ash 2.

division Glass
CaO Discoloration time Discoloration reagent 1.0%
Acid solution 0%
(Mixed ratio 1: 1) Discoloration reagent 1.0%
Acid solution 3.0%
(Mixed ratio 1: 1) Discoloration reagent 1.0%
Acid solution 6.0%
(Mixed ratio 1: 1) cement 1.23% 30 seconds 5 minutes 9 minutes Fly Ash 1 0% Unreacted Unreacted Unreacted Fly Ash 2 2.1% 1 minute Unreacted Unreacted Fly Ash 3 2.5% 55 seconds Unreacted Unreacted Fly Ash 4 5.0% 30 seconds 30 minutes 57 minutes Fly Ash 5 10.0% 14 sec 8 minutes 15 minutes

In the experiment, 15 ml of a discoloration indicator (a discoloration reagent, a mixed solution of an acid solution) was added to 5 g of each sample, and the time of discoloration of the sample was measured after stirring. When the acidic solution was 0%, both the fly ash glass CaO KS standards (2.5% or less) fly ash 2 to 3 and the fly ash 4 to 5 that does not meet the KS standards were discolored. In the case of 3.0% and 6.0% of the acidic solution in which the acidic solution content was adjusted by the method of the present invention, only the samples of fly ashes 4 to 5 exceeding the fly ash free CaO KS standard (2.5% or less) were discolored.

(Example 2)

The discoloration indicator of this invention can adjust the discoloration time of a sample suitably by adjusting the density | concentration of the discoloration reagent mixed with an acidic solution. Table 3 is a graph showing the results of measuring the discoloration time by changing the concentration of the discoloration reagent. As in Example 1, 15 ml of color change indicator was used for 5 g of the sample.

As can be seen from Table 3, increasing the concentration of the discoloration reagent shortens the discoloration time.

By properly adjusting the discoloration reagent content by the method proposed in the present invention, it is possible to shorten the discoloration time, and control the fly ashes 2 to 3 that satisfy the fly ash free CaO KS standard so as not to discolor.

division Glass
CaO Discoloration time Discoloration reagent 0.5%
Acid solution 3.0%
(Mixed ratio 1: 1) Discoloration reagent 1.0%
Acid solution 3.0%
(Mixed ratio 1: 1) Discoloration reagent 1.5%
Acid solution 3.0%
(Mixed ratio 1: 1) cement 1.23% 5.5 minutes 5 minutes 4 minutes Fly Ash 1 0% Unreacted Unreacted Unreacted Fly Ash 2 2.1% Unreacted Unreacted Unreacted Fly Ash 3 2.5% Unreacted Unreacted Unreacted Fly Ash 4 5.0% 40 minutes 30 minutes 20 minutes Fly Ash 5 10.0% 11 minutes 8 minutes 4 minutes

 (Example 3)

In the present invention, it is possible to control the discoloration time by adjusting the amount of discoloration indicator mixed with the discoloration reagent and acid solution.

Table 4 is a graph showing the results of measuring the discoloration time according to the color change indicator usage. It can be seen that the discoloration time increases when the discoloration indicator is used. When the amount of discoloration indicator is increased, the amount of acid solution mixed in the discoloration indicator increases, neutralizing alkali eluted from the sample, suppressing the increase of pH, and delaying discoloration time. By controlling the amount of discoloration indicators proposed in the present invention, it is possible to control the discoloration range for each discoloration time and fly ash free CaO content.

division Glass
CaO Discoloration time Discoloration reagent 0.5%
Acid solution 3.0%
(Mixed ratio 1: 1) Discoloration reagent 0.5%
Acid solution 3.0%
(Mixed ratio 1: 1) Discoloration reagent 0.5%
Acid solution 3.0%
(Mixed ratio 1: 1) 5 g of sample
Discoloration Indicator 35ml 5 g of sample
Discoloration Indicator 25ml 5 g of sample
Discoloration Indicator 15ml cement 1.23% 17 minutes 11 minutes 5.5 minutes Fly Ash 1 0% Unreacted Unreacted Unreacted Fly Ash 2 2.1% Unreacted Unreacted Unreacted Fly Ash 3 2.5% Unreacted Unreacted Unreacted Fly Ash 4 5.0% Unreacted Unreacted 40 minutes Fly Ash 5 10.0% 45 minutes 25 minutes 11 minutes

(Example 4)

It is possible to control the discoloration time by adjusting the mixing ratio (volume ratio) of the discoloring reagent and the acid solution proposed in the present invention. Table 5 shows the discoloration time by mixing ratio of discoloration reagent and acid solution. For 5 g of sample, 15 ml of color change indicator was used.

The discoloration time was delayed when the mixing ratio of the acid solution was increased. Increasing the mixing ratio of the acid solution in the color change indicator neutralizes the alkali eluted from the sample, inhibits the increase in pH, and delays the color change time. It is possible to control the discoloration time by controlling the mixing ratio of the discoloration reagent and acid solution proposed in the present invention.

division Glass
CaO Discoloration time Discoloration reagent 0.5%
Acid solution 3.0%
(Mixing ratio 1: 0.5) Discoloration reagent 0.5%
Acid solution 3.0%
(Mixed ratio 1: 1) Discoloration reagent 0.5%
Acid solution 3.0%
(Mixed ratio 1: 1.5) cement 1.23% 3 minutes 5.5 minutes 8 minutes Fly Ash 1 0% Unreacted Unreacted Unreacted Fly Ash 2 2.1% Unreacted Unreacted Unreacted Fly Ash 3 2.5% 68 minutes Unreacted Unreacted Fly Ash 4 5.0% 35 minutes 40 minutes 60 minutes Fly Ash 5 10.0% 10 minutes 11 minutes 15 minutes

(Example 5)

It is possible to quickly evaluate whether it is a cement or a material other than cement by using a color change indicator suitably adjusted in the mixing ratio of the color change reagent and the acid solution proposed in the present invention.

Figure 2 is a photograph showing the test method of the discoloration indicator reagent developed by using phenolphthalein as the discoloration reagent. In Figure 2 (a) is a state in which the sample is measured and added, (b) is a state of discoloring indicators added to the sample, (c) is a state of stirring after the discoloration indicators added, (d) is a photograph of the reaction results to be.

3 is a photograph showing an example in which the discoloration state of the fly ash and cement is changed using the same discoloration indicator.

The left photograph of FIG. 3 is a fly ash, and the right photograph is a photograph of cement. Cement discolors red, and fly ash that meets the glass Ca KS standard (2.5% or less) does not discolor. By the discoloration indicator and test method proposed in the present invention, it is possible to inspect whether cement is a material other than cement before it is brought to the site and transferred to a storage silo. It can prevent the input.

Claims (2)

0.1-10% by weight of at least one selected from the group consisting of phenolphthalein, thymolphthalein, nitramine, and trinitrobenzene (ethanol, benzene, hexane ( Hexane, Chloroform, ether, Dichloromethane, Tetrahydrofuran, Ethyl acetate, Methanol, Isopropyl alcohol, Water, Dimethylsulfoxide Discoloration reagents dissolved in seeds (dimethyl sulfoxide), dimethylformamide, and acetonitrile; And hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (mP ₂ O ₅ nH ₂ O), carbonic acid (H ₂ CO ₃ ) and acetic acid (C ₂ H ₄ O ₂ ) At least one selected from the group consisting of 0.1 ~ 10% by volume of the acid solution mixed with water,
The discoloration reagent and the acid discoloration indicator is a cement discoloration indicator, characterized in that mixed in a volume ratio of 1: 0.1 ~ 1:10. Cement test method characterized in that it determines the cement by mixing the color change indicator of claim 1.

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