JP2010181362A - Device and method for decision of alkali-silica reactivity in aggregate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decision device and method capable of reliably and quickly determining alkali-silica reactivity in an aggregate by an electrochemical method. <P>SOLUTION: The alkali-silica reactivity decision device includes an aggregate whose alkali-silica reactivity is unknown, a container for storing water or phosphoric acid aqueous solution, a diaphragm disposed so as to divide the container into two chambers, two electrodes arranged oppositely across the diaphragm, and a membrane potential measuring part electrically connected to each electrode. The aggregate is added into each of the two chambers so that each addition amount of the aggregate is different, relative to the volume of the water or the phosphoric acid aqueous solution in each of the two chambers storing the water or the phosphoric acid aqueous solution. When the membrane potential after elapse of a prescribed time is below 0 V, it is determined that the aggregate has high alkali-silica reactivity, and when the membrane potential is over 0 V, it is determined that the aggregate has low alkali-silica reactivity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus and method for determining the alkali-silica reactivity of aggregates.

Alkali-silica reaction (alkali-aggregate reaction) causes the product generated by the reaction between silica (SiO ₂ ) in the aggregate and the alkali contained in the concrete to absorb water and expand, causing cracks and the like in the concrete. It is a phenomenon.

  Alkali-silica reaction is difficult to suppress once deterioration begins, as is also called “concrete cancer”, and will eventually cause serious damage to concrete structures. Therefore, it is necessary to exclude the aggregate having alkali silica reactivity, and various test methods for evaluating the alkali silica reactivity of the aggregate have been proposed.

  The features of the alkali-silica reaction are (1) the point caused by specific minerals in the aggregate, (2) the chemical reaction, and (3) the point of expansion and deterioration of concrete. Test methods for evaluating the alkali-silica reactivity of the material are roughly classified into (1) mineralogical observation test, (2) chemical method, and (3) expansion change test.

  Mineralogical observation test method involves directly observing rocks with a polarizing microscope, etc., and reactive siliceous minerals (opal, chalcedony, tridymite, cristobalite, hidden microcrystalline / amorphous silica, strained quartz, silica Quality volcanic glass etc.) or a reactive carbonate mineral (dolomite) is observed. JCI-DD3 is equivalent to this in Japan, and it is a test method specialized for harmful minerals. It has become.

  In the chemical method, when the aggregate and alkali are reacted and the amount of silica eluted (Sc: mmol / L) and the amount of alkali consumed (Rc: mmol / L) is Rc / Sc ≧ 1 Is a technique for determining that the aggregate is harmless (low alkali silica reactivity), and is represented by ASTM-C289 and JIS-A1145. In the chemical method, since the aggregate is dissolved in an alkali, the aggregate is pulverized so that the particle size is 150 to 300 μm in consideration of the influence of the aggregate particle size on the result (non-non-conductive). Patent Document 1). In addition, the time for the reaction between the aggregate and the alkali to reach equilibrium is 100 hours or more, but considering that the reaction time affects the result, the reaction time is set to 24 hours ± 15 minutes (non-patent) Reference 1). In addition, the amount of silica eluted from the aggregate is quantified by mass method, atomic absorption spectrophotometry or spectrophotometry, and the alkali consumption is measured by titration with hydrochloric acid using a phenolphthalein indicator (Non-patent Document 1). reference).

  The expansion change test method (mortar bar method) is a technique for forming a mortar with an aggregate sample in which the particle size composition is adjusted to the sand size, and determining the reactivity from the amount of expansion, and is represented by ASTM-C227 and JIS-A1146. Is done. The expansion change test gives relatively stable results, but requires a period of at least 6 months for determination.

  Of the above three test methods, chemical methods that can obtain results in a relatively short period of time are widely used. In order to quantify the amount of silica eluted from the aggregate in the chemical method, the mass method, atomic absorption photometry method or It is necessary to use absorptiometry.

  However, quantifying the amount of silica eluted by mass spectrometry, atomic absorption spectrophotometry, or spectrophotometry is cumbersome, and particularly in atomic absorption spectrophotometry or spectrophotometry, advanced techniques are required to measure absorbance. There is a problem that.

  Therefore, a new method capable of quickly and easily determining the alkali-silica reactivity of the aggregate is desired. Conventionally, a method for determining the alkali-silica reactivity of the aggregate using an electrochemical method. Has been proposed (see Non-Patent Document 2).

Japanese Industrial Standard Aggregate Alkali Silica Reactivity Test Method (Chemical Method) JIS-A1145: 2001 Published by Japanese Standards Association Architectural Institute of Japan, “Proposed Proposal for Rapid Judgment of Reactive Aggregate from an Electrochemical Perspective”, Shinichiro Fukuda, Naomitsu Tsurugi, Yoshio Kasai, No. 499, pp. 1-8 1997

  In the method for determining the alkali-silica reactivity of aggregate using the electrochemical method described in Non-Patent Document 2, pure water (distilled water) is contained in two water tanks partitioned by a tracing paper diaphragm. Then, adding the aggregate whose alkali silica reactivity is unknown in one water tank, measuring the membrane potential, and determining the alkali silica reactivity of the aggregate based on the measurement result of the membrane potential, Depending on the determination method, there is a problem that it may be difficult to determine the alkali-silica reactivity of the aggregate, as is apparent from the test results of the test examples described later.

  In view of the above problems, an object of the present invention is to provide a determination apparatus and a determination method that can reliably and quickly determine the alkali-silica reactivity of an aggregate by an electrochemical method.

  In order to solve the above-described problems, the present invention divides an aggregate in which alkali-silica reactivity is unknown, water or a phosphoric acid aqueous solution, and the container into a first chamber and a second chamber. In this way, a diaphragm made of a hydrophilic porous membrane having a carboxyl group, a hydroxyl group, a sulfonic acid group or a perfluorosulfonic acid group on the surface, which is disposed in the container, and the diaphragm are opposed to each other. Two electrodes disposed in each of the first chamber and the second chamber, and a membrane potential measuring unit electrically connected to each of the electrodes, the water or phosphoric acid aqueous solution being contained The aggregate is added to each of the first chamber and the second chamber so that the amount of the aggregate added to the capacity of the water or phosphoric acid aqueous solution in each of the first chamber and the second chamber is different, and Measured by the membrane potential measurement unit When the membrane potential is less than 0 V, the aggregate is determined to have high alkali silica reactivity, and when the membrane potential is 0 V or more, the aggregate is determined to have low alkali silica reactivity. An aggregate-silica alkali-silica reactivity determination device is provided (claim 1).

  According to the above invention (invention 1), the inside of the container is divided by a predetermined diaphragm, and the amount of aggregate added in each divided chamber (addition amount with respect to the volume of water or phosphoric acid aqueous solution) is made different. By measuring the membrane potential, it is possible to reliably and quickly determine the alkali silica reactivity of the aggregate based on the measurement result of the membrane potential.

This is considered to be based on the following actions.
In general, the membrane potential in an aqueous solution containing ions (cations and anions) eluted from the aggregate is expressed by the following formula (1), similarly to the aqueous electrolyte solution containing many kinds of ions.

In the above formula (1), Δφ is the “diffusion potential (membrane potential)”, Δφ ₁ and Δφ ₂ are the “membrane potential on the electrolyte aqueous solution 1 (electrolyte aqueous solution in contact with one side of the membrane, low addition amount) side” and “Membrane potential of electrolyte aqueous solution 2 (electrolyte aqueous solution in contact with the other side of membrane, high addition amount) side”, R is “gas constant (= 8.3145 (Jmol ⁻¹ K ⁻¹ ))”, and T is “absolute temperature , F is the “Faraday constant (= 9.6485 × 10 ⁴ (Cmol ⁻¹ ))”, C ₊₁ and C ₊₂ are “the cation concentration on the membrane surface in contact with the aqueous electrolyte solution 1” and “the aqueous electrolyte solution 2”, respectively. C- ₁ and C- ₂ are "anion concentration of the film surface in contact with the aqueous electrolyte solution 1" and "anion of the film surface in contact with the aqueous electrolyte solution 2," respectively. “Ion concentration”, P ₊ and P ₋ are “ion permeability coefficient or molar mobility of ion”, respectively. Represents.

  When the aggregate is immersed in water or an aqueous phosphoric acid solution, ions (for example, cations such as iron ions, magnesium ions, aluminum ions, calcium ions, sodium ions, and potassium ions; anions such as silicate ions) are water. Or it is soluble in phosphoric acid aqueous solution, but has a carboxyl group, hydroxyl group, sulfonic acid group, perfluorosulfonic acid group, etc. on the surface of the diaphragm, so that the amount of aggregate added to the capacity of water or phosphoric acid aqueous solution is large Only cations move from (electrolyte aqueous solution 2) to the smaller one (electrolyte aqueous solution 1).

In this case, when the amount of cation dissolved in water or an aqueous phosphoric acid solution is small, such as an aggregate having low alkali silica reactivity, in the above formula (1),
_{ΣP + C +1 + ΣP - C} -1 <ΣP + C +2 + ΣP - C -2
Or
ΣP ₋ C ₋₁ <ΣP ₋ C ₋₂
Therefore, the membrane potential of the diaphragm is considered to be represented by the following formula (2).

On the other hand, when the amount of cation dissolved in water or aqueous phosphoric acid solution is large, such as aggregate having high alkali silica reactivity, the cation eluted from the aggregate present in the electrolyte aqueous solution 2 is separated from the diaphragm. When adsorbed on the diaphragm when moving to the electrolyte aqueous solution 1 side through the above formula (1),
ΣP ₊ C _{+ 1} + ΣP _- C- ₁ > ΣP _- C- ₂
When the cation eluted from the aggregate present in the electrolyte aqueous solution 2 moves to the electrolyte aqueous solution 1 side through the diaphragm, in the above formula (1),
ΣP ₊ C _{+ 1} + ΣP ₋ C− ₁ + ΣP ₊ C _{+ 2} > ΣP ₋ C− ₂
Therefore, the membrane potential of the diaphragm is considered to be represented by the following formula (3).

  Therefore, according to the said invention (invention 1), the alkali-silica reactivity of an aggregate can be determined reliably and rapidly by using the measured value of the membrane potential as an index.

  In the said invention (invention 1), the said aggregate with respect to the capacity | capacitance of the said water or phosphoric acid aqueous solution to the said 2nd chamber and the addition amount of the said aggregate with respect to the capacity | capacitance of the said water or phosphoric acid aqueous solution to the said 1st chamber It is preferable that the ratio with respect to the addition amount is 1: 0.96 to 0.99.

  According to the said invention (invention 2), since the addition amount of the aggregate in the 1st chamber and the 2nd chamber of the divided | segmented two chambers exists in the said range, the alkali silica reactivity of an aggregate is made. The determination can be made more reliably and quickly.

  In the said invention (invention 2), it is preferable that the addition amount of the said aggregate with respect to the capacity | capacitance of the said water or phosphoric acid aqueous solution to the said 1st chamber is 0.015-0.04g / mL (invention). 3).

  In the said invention (invention 1-3), it is preferable that the density | concentration of the said phosphoric acid aqueous solution is 15-30 micromol / L (invention 4). According to this invention (invention 4), by setting the concentration of the phosphoric acid aqueous solution within the above range, the alkali silica reactivity of the aggregate can be more reliably and promptly determined.

  In the said invention (invention 1-4), it is preferable that the particle size of the said aggregate is 75-150 micrometers (invention 5). If the particle size of the aggregate exceeds 150 μm, it may take time to determine alkali-silica reactivity depending on the amount of aggregate added to each chamber of the container, and accurate determination may be difficult. When the particle size of the aggregate is less than 75 μm, aggregation occurs in water or an aqueous phosphoric acid solution, resulting in variations in the amount of dissolved ions from the aggregate, which may make accurate determination difficult. However, according to this invention (invention 5), by setting the particle size of the aggregate to 75 to 150 μm, it is possible to reliably and promptly determine the alkali silica reactivity of the aggregate.

  The present invention also provides a container divided into two chambers, a first chamber and a second chamber, through a diaphragm made of a hydrophilic porous membrane having a carboxyl group, a hydroxyl group, a sulfonic acid group or a perfluorosulfonic acid group on the surface. In the first chamber and the second chamber, an aggregate of which alkali silica reactivity is unknown and water or a phosphoric acid aqueous solution are used, and the aggregate with respect to the capacity of the water or the phosphoric acid aqueous solution in the first chamber and the second chamber. When the membrane potential of the diaphragm measured in a state where the aggregate and water or phosphoric acid aqueous solution are in contact with each other in the first chamber and the second chamber is less than 0 V In addition, it is determined that the aggregate has a high alkali silica reactivity, and when the membrane potential is 0 V or more, it is determined that the aggregate has a low alkali silica reactivity. Provide reactivity determination method Claim 6).

  According to the above invention (invention 6), the aggregate and water or the phosphoric acid aqueous solution are added so that the amount of the aggregate added to each room divided by the predetermined diaphragm is different. Alternatively, by measuring the membrane potential of the diaphragm in contact with the phosphoric acid aqueous solution, the alkali-silica reactivity of the aggregate can be reliably and rapidly determined based on the measurement result of the membrane potential.

  In the said invention (invention 6), the said aggregate with respect to the capacity | capacitance of the said water or phosphoric acid aqueous solution with respect to the capacity | capacitance of the said water or phosphoric acid aqueous solution to the said 1st chamber, and the capacity | capacitance of the said water or phosphoric acid aqueous solution to the said 2nd chamber It is preferable to add the aggregate and the water or the phosphoric acid aqueous solution to each of the first chamber and the second chamber so that the ratio to the addition amount is 1: 0.96 to 0.99 ( Claim 7).

  According to the said invention (invention 7), since the ratio of the addition amount of aggregate is in the said range, the alkali silica reactivity of aggregate can be determined more reliably and rapidly.

  In the said invention (invention 7), it is preferable that the addition amount of the said aggregate with respect to the capacity | capacitance of the said water or phosphoric acid aqueous solution to the said 1st chamber is 0.015-0.04 g / mL (invention). 8).

  In the said invention (invention 6-8), it is preferable that the density | concentration of the said phosphoric acid aqueous solution is 15-30 micromol / L (invention 9), In the said invention (invention 6-9), it is said bone. It is preferable that the particle diameter of the material is 75 to 150 μm.

  ADVANTAGE OF THE INVENTION According to this invention, the determination apparatus and determination method which can determine the alkali silica reactivity of an aggregate reliably and rapidly by an electrochemical method can be provided.

It is a schematic sectional drawing which shows the alkali silica reactivity determination apparatus of the aggregate which concerns on one Embodiment of this invention.

Hereinafter, an aggregate alkali-silica reactivity determination device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an aggregate alkali-silica reactivity determination device according to this embodiment.

  As shown in FIG. 1, the aggregate alkali-silica reactivity determination device 1 according to the present embodiment includes a first chamber 21 and a second chamber 22 that are open at the top, and a first chamber 21 and a second chamber 22. A container 2 having a U-shaped cross section having a connecting portion 23 connected at the lower portion thereof, electrodes 3A and 3B disposed in the first chamber 21 and the second chamber 22, and two electrodes 3A and 3B, respectively. And an electrically connected membrane potential measuring device 4.

  Each of the upper surface portion and the lower surface portion of the connecting portion 23 of the container 2 is provided with protrusions 23A and 23B extending in the horizontal direction of the first chamber 21 and the second chamber 22, and the protrusions 23A and 23B are provided with the protrusions 23A and 23B. By attaching both ends of the diaphragm 5, the inside of the container 2 is divided into two chambers of the first chamber 21 side and the second chamber 22 side.

  The material of the container 2 is not particularly limited, but it is preferable that the components cannot be eluted in water or phosphoric acid aqueous solution contained in the container 2, for example, glass, Examples thereof include olefin resins such as polyethylene and polypropylene.

  As the diaphragm 5, for example, a hydrophilic porous membrane having a carboxyl group, a hydroxyl group, a sulfonic acid group, or a perfluorosulfonic acid group on the surface can be used. Depending on the alkali silica reactivity of the aggregate, the concentration of ions (cation concentration and anion concentration) dissolved in water or phosphoric acid aqueous solution may vary. Therefore, if these hydrophilic porous membranes are used as the diaphragm 5, the membrane potential changes according to the mobility of cations dissolved in water or phosphoric acid aqueous solution, the amount of adsorption to the diaphragm, etc. By measuring, the alkali-silica reactivity of the aggregate can be reliably and promptly determined.

  As the diaphragm 5 (hydrophilic porous membrane), a cation exchange membrane can be suitably used, but tracing paper having a carboxyl group on the surface may be used. When the tracing paper is used as the diaphragm 5 (hydrophilic porous membrane), a phosphoric acid aqueous solution having a predetermined concentration is contained in the first chamber 21 and the second chamber 22 of the container 2 as is apparent from a test example described later. Need to be accommodated. Thereby, the carboxyl group of the tracing paper surface is phosphorylated, and the alkali silica reactivity of the aggregate can be reliably determined.

  The thickness of the diaphragm 5 may be appropriately set depending on the amount of functional group introduced such as carboxyl group, hydroxyl group, sulfonic acid group or perfluorosulfonic acid group, but is preferably 250 μm or less, and preferably 125 to 250 μm. More preferred. If the film thickness exceeds 250 μm, it is difficult to move dissolved ions in water or an aqueous phosphoric acid solution, and thus it may be difficult to reliably determine the alkali silica reactivity of the aggregate.

The electrodes 3A and 3B are not particularly limited. For example, a platinum wire or a platinum plate may be used. The membrane potential measuring device 4 is not particularly limited as long as it can measure the membrane potential of the diaphragm 5 provided in the connecting portion 23 of the container 2, and has a high input capable of measuring a minute potential change. An electrode potential measuring device having resistance (10 ¹¹ to 10 ¹⁴ Ω), for example, an electrometer, a potentiostat or the like can be used.

  In order to determine the alkali silica reactivity of the aggregate using the aggregate alkali silica reactivity determination apparatus 1 having such a configuration, first, water or a phosphoric acid aqueous solution is added to the first chamber 21 and the second chamber 22. It is preferable to contain W, particularly an aqueous phosphoric acid solution. Since the phosphoric acid aqueous solution accommodated in the first chamber 21 and the second chamber 22 is an aqueous solution having high electrical conductivity, the potential fluctuation at the time of measurement is reduced, and the potential can be measured more accurately. Before the addition, the membrane 5 (hydrophilic porous membrane) was immersed in a phosphoric acid aqueous solution, so that the surface of the membrane 5 was modified with phosphoric acid and the cation adsorption was improved. It becomes possible to determine the alkali-silica reactivity of the aggregate by the electric potential.

The water contained in the first chamber 21 and the second chamber 22 is preferably one from which electrolyte components and the like are removed as much as possible. Specifically, the electrical resistivity (specific resistance) is 0. 1 to 1 × is preferably of the order of 10 ⁶ Ω · cm. Examples of such water include pure water, distilled water, purified water, and ion exchange water.

When the phosphoric acid aqueous solution is accommodated in the first chamber 21 and the second chamber 22, the concentration of the phosphoric acid aqueous solution is preferably 10 to 30 μmol / L, and particularly preferably 20 to 25 μmol / L. When the concentration of the phosphoric acid aqueous solution exceeds 30 μmol / L, it is considered that an insoluble salt is generated from the cation (metal ion) and phosphate ion (PO ₄ ³⁻ ) eluted from the aggregate, It may be difficult to determine the alkali-silica reactivity of the aggregate.

  The temperature of the water or phosphoric acid aqueous solution accommodated in the first chamber 21 and the second chamber 22 is preferably 20 to 30 ° C, and particularly preferably about 20 ° C. In addition, what is necessary is just to immerse the container 2 in warm water, such as a water bath, and to heat when making temperature into about 30 degreeC.

  While containing water or phosphoric acid aqueous solution W in the first chamber 21 and the second chamber 22, an aggregate A whose alkali silica reactivity is unknown (hereinafter simply referred to as “aggregate”) is added. Thereby, based on the change of the membrane potential according to the amount of dissolved ions from the aggregate A, the alkali silica reactivity of the aggregate A can be determined.

  In this case, the amount of aggregate A added to the capacity of the water or phosphoric acid aqueous solution W added to the first chamber 21 (hereinafter sometimes simply referred to as “aggregate added amount”) and added to the second chamber 22. Aggregate A is added to each of the first chamber 21 and the second chamber 22 so that the amount of the aggregate added to the volume of the water or phosphoric acid aqueous solution is different. For example, the aggregate addition amount in the second chamber 22 may be less than the aggregate addition amount in the first chamber 21, or vice versa. In the present embodiment, the aggregate addition amount in the first chamber 21 is set higher than the aggregate addition amount in the second chamber 22.

  Specifically, for example, the aggregate A is set so that the ratio of the aggregate addition amount in the first chamber 21 and the aggregate addition amount in the second chamber 22 is 1: 0.96 to 0.99. It is preferable to add to the chamber 21 and the second chamber 22, and it is particularly preferable to add so as to be 1: 0.96 to 0.98. If the ratio of the aggregate addition amount is within the above range, the alkali silica reactivity of the aggregate A can be determined more reliably and quickly.

  The aggregate addition amount in the first chamber 21 is preferably 0.015 to 0.04 g / mL, and particularly preferably 0.025 to 0.037 g / mL. If the aggregate addition amount is less than 0.015 g / mL or the aggregate addition amount exceeds 0.04 g / mL, it may be difficult to determine the alkali silica reactivity of the aggregate A.

  The particle size (average particle size) of the aggregate A added to the first chamber 21 and the second chamber 22 is preferably 75 to 300 μm, and more preferably 75 to 150 μm. When the particle size of the aggregate is less than 75 μm, fine powder aggregates, resulting in variations in the amount of dissolved ions from the aggregate, making it difficult to determine the alkali silica reactivity of the aggregate A. There is a risk of becoming.

  The membrane potential is measured after a predetermined time has elapsed since the aggregate A is added to the first chamber 21 and the second chamber 22 of the container 2 and the water or phosphoric acid aqueous solution W and the aggregate A are brought into contact with each other. Measured according to 4.

  The measurement time of the membrane potential may be within 60 minutes, preferably 1 to 30 minutes, particularly preferably 1 to 5 minutes. Even if the measurement is continued for more than 60 minutes, improvement in the determination accuracy of the alkali silica reactivity of the aggregate A cannot be expected, which may be uneconomical.

  When the membrane potential measured in this way is 0 V or more, it can be determined that the aggregate is low in alkali silica reactivity, that is, the aggregate is “harmless”. On the other hand, when the membrane potential is less than 0 V, it can be determined that the aggregate has high alkali-silica reactivity, that is, the aggregate is not harmless.

  According to the aggregate alkali-silica reactivity determination apparatus 1 according to the present embodiment, water or a phosphoric acid aqueous solution W is provided in each of the first chamber 21 and the second chamber 22 that are divided (partitioned) by a diaphragm. And the aggregate A are added so that the aggregate addition amounts of the first chamber 21 and the second chamber 22 are different, and the membrane potential is measured in that state, within 60 minutes, preferably 1 to 5 The alkali silica reactivity of the aggregate A can be determined reliably in a short time of about a minute. In addition, skilled alkali operation is not required, and the alkali silica reactivity of the aggregate A can be determined only by simple work.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[Aggregate alkali-silica reactivity test by chemical method]
A plurality of aggregates randomly extracted from a plurality of aggregates of a predetermined production area are used as test samples (aggregates 1 to 7), and these aggregates are tested for alkali silica reactivity based on JIS-A1145 (chemical method). Did.
The results are shown in Table 1.

  As a result of the test by the above chemical method, it is confirmed that the aggregates 1 to 4 are aggregates that can be determined as “harmless”, and the aggregates 5 to 7 are aggregates that can be determined as “not harmless”. It was.

[Aggregate alkali-silica reactivity determination test 1]
An aggregate alkali-silica reactivity determination apparatus 1 shown in FIG. 1 was prepared, and membrane potentials of the aggregate 1 and the aggregate 5 were measured. Water or a phosphoric acid aqueous solution (97 mL in the first chamber 21 and 85 mL in the second chamber 22) is used as a solvent, and a perfluorosulfonic acid membrane (manufactured by DuPont, trade name: Nafion, film thickness: 125 μm (D125) in the second chamber 22 is contained. ), 250 μm (D250)), platinum electrodes were used as the electrodes 3A and 3B, and an electrometer (product name: Electrometer HE-106, manufactured by Hokuto Denko Co., Ltd.) was used as the membrane potential measuring device 4.
The results are shown in Table 2.

  As shown in Table 2, the aggregate concentration in the first chamber and the second chamber of the alkali silica reactivity determination device (the amount of aggregate added relative to the volume of pure water or phosphoric acid aqueous solution) is made different, and a cation is used as a diaphragm. By using an exchange membrane, it is possible to reliably determine the alkali silica reactivity of the aggregate. In particular, the ratio (L / H) of the low concentration of aggregate (aggregate concentration in the second chamber, L in Table 2) to the high concentration aggregate (aggregate concentration in the first chamber, H in Table 2). Is 0.96 to 0.98, it was confirmed that the alkali-silica reactivity of the aggregate can be determined quickly and reliably. In addition, even if the ratio (L / H) is 0.99, it is considered that the alkali silica reactivity of the aggregate can be determined by containing the phosphoric acid aqueous solution in the first chamber and the second chamber. .

[Alkali-silica reactivity test 2]
In the alkali silica reactivity determination apparatus 1 used in the alkali silica reactivity determination test 1 of the above aggregate, a tracing paper (manufactured by Ostrich Diamond Co., Ltd., trade name: reinforced tracing) instead of the perfluorosulfonic acid film as the diaphragm 5 is used. Paper, film thickness: 60 μm, unit area mass: 50 g / m ² , average pore diameter: 28 nm), membrane potential was measured for aggregate 1 and aggregate 5.
The results are shown in Table 3.

  As shown in Table 3, when tracing paper is used as the diaphragm 5 of the aggregate alkali-silica reactivity determination apparatus 1 and pure water is accommodated in the first chamber 21 and the second chamber 22, the aggregate 1 and the aggregate 5 are used. In any case, the measurement result of the membrane potential is less than 0 V, and it is clear that it is difficult to accurately determine the alkali silica reactivity of the aggregate. However, even if tracing paper is used as the diaphragm 5, the alkali silica reactivity of the aggregate can be determined by accommodating a 10-30 μmol / L phosphoric acid aqueous solution in the first chamber 21 and the second chamber 22. It was confirmed.

  By immersing the tracing paper in an aqueous phosphoric acid solution, it is considered that the carboxyl group on the surface of the tracing paper is phosphorylated and the adsorption ability of metal ions (cations) dissolved from the aggregate is improved. At this time, when the amount of dissolved cation is small as in the aggregate having low alkali silica reactivity, the measured membrane potential is expressed by the above formula (2). On the other hand, when the amount of dissolved cation is large, such as an aggregate having high alkali silica reactivity, the measured membrane potential is represented by the above formula (3). Therefore, it is considered that the alkali-silica reactivity of the aggregate can be determined as in the above result.

  The aggregate-silica alkali-silica reactivity determination apparatus according to the present invention is useful for quick and reliable determination of the reactivity of aggregates whose alkali-silica reactivity is unknown.

DESCRIPTION OF SYMBOLS 1 ... Aggregate alkali silica reactivity determination apparatus 2 ... Container 21 ... 1st chamber 22 ... 2nd chamber 3A, 3B ... Electrode 4 ... Membrane potential measuring device 5 ... Diaphragm

Claims (10)

A container in which an aggregate of which alkali silica reactivity is unknown and water or an aqueous phosphoric acid solution are contained;
A hydrophilic porous membrane having a carboxyl group, a hydroxyl group, a sulfonic acid group, or a perfluorosulfonic acid group on the surface disposed in the container so as to divide the container into a first chamber and a second chamber A diaphragm consisting of
Two electrodes disposed in each of the first chamber and the second chamber so as to face each other across the diaphragm;
A membrane potential measuring unit electrically connected to each of the electrodes,
The first chamber and the second chamber so that the amount of the aggregate added to the capacity of the water or the phosphoric acid aqueous solution in each of the first chamber and the second chamber containing the water or the phosphoric acid aqueous solution is different. When the aggregate is added to each of them, and the membrane potential measured by the membrane potential measuring unit is less than 0 V, it is determined that the alkali silica is highly reactive, and the membrane potential is 0 V or more. In some cases, the aggregate alkali-silica reactivity determination apparatus determines that the aggregate has low alkali-silica reactivity.   The ratio of the amount of the aggregate added to the volume of the water or phosphoric acid aqueous solution to the first chamber and the amount of the aggregate added to the volume of the water or phosphoric acid aqueous solution to the second chamber is 1 It is 0.96-0.99, The alkali silica reactivity determination apparatus of the aggregate of Claim 1 characterized by the above-mentioned.   3. The aggregate alkali silica according to claim 2, wherein an amount of the aggregate added to the capacity of the water or phosphoric acid aqueous solution to the first chamber is 0.015 to 0.04 g / mL. Reactivity determination device.   4. The aggregate alkali-silica reactivity determination apparatus according to claim 1, wherein the concentration of the phosphoric acid aqueous solution is 15 to 30 [mu] mol / L.   The aggregate silica-silica reactivity determination apparatus according to claim 1, wherein the aggregate has a particle size of 75 to 150 μm. The first chamber of the container divided into two chambers, a first chamber and a second chamber, through a diaphragm made of a hydrophilic porous membrane having a carboxyl group, a hydroxyl group, a sulfonic acid group or a perfluorosulfonic acid group on the surface; In the second chamber, the amount of addition of the aggregate with respect to the capacity of the water or phosphoric acid aqueous solution in the first chamber and the second chamber is different between the aggregate of which alkali silica reactivity is unknown and water or phosphoric acid aqueous solution. And add
When the membrane potential of the diaphragm measured with the aggregate and water or phosphoric acid aqueous solution in contact with each other in the first chamber and the second chamber is less than 0 V, the alkali silica reactivity of the aggregate is A method for determining an alkali-silica reactivity of an aggregate, characterized in that, when the membrane potential is determined to be high and the membrane potential is 0 V or higher, it is determined that the alkali-silica reactivity of the aggregate is low.   The ratio of the amount of the aggregate added to the volume of the water or phosphoric acid aqueous solution to the first chamber and the amount of the aggregate added to the volume of the water or phosphoric acid aqueous solution to the second chamber is 1: 0. The aggregate of claim 6, wherein the aggregate and the water or phosphoric acid aqueous solution are added to each of the first chamber and the second chamber so as to be .96 to 0.99. Alkali-silica reactivity determination method.   The aggregate alkali silica according to claim 7, wherein the amount of the aggregate added to the capacity of the water or phosphoric acid aqueous solution to the first chamber is 0.015 to 0.04 g / mL. Reactivity determination method.   The method for determining alkali silica reactivity of an aggregate according to any one of claims 6 to 8, wherein the concentration of the aqueous phosphoric acid solution is 15 to 30 µmol / L.   The method for determining alkali-silica reactivity of an aggregate according to any one of claims 6 to 9, wherein the aggregate has a particle size of 75 to 150 µm.

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