JP7427987B2 - Test method for cement composition and test specimen - Google Patents

Description

The present invention relates to a method for testing a cement composition and a test specimen.

Generally, when measuring the carbonation rate of cement compositions (e.g., concrete or mortar) in a short period of time, accelerated carbonation test equipment is used to accelerate the carbonation of the test specimen under environmental conditions with high carbon dioxide concentration. We are conducting a test.

Furthermore, with respect to surface finishing materials (paints, etc.) for cement compositions, accelerated weather resistance tests are conducted by applying the surface finishing materials to thin iron plates, etc. (see, for example, Patent Document 1). After the test, the surface finishing material is peeled off from the iron plate and applied to the surface of the cement composition, and other tests (such as an accelerated carbonation test) are performed.

Japanese Patent Application Publication No. 2015-85515

However, in the above-mentioned test method, an accelerated weathering test is not conducted under conditions close to those of actual use, so there is a risk that evaluations close to natural phenomena may not be obtained.

The present invention has been made in view of such problems, and its purpose is to enable accelerated weathering tests to be performed under conditions close to those of actual use.

The main invention for achieving the above purpose is:
A covering material construction step of constructing a resin film, tile, or stone as a covering material on a predetermined surface of a substrate formed of a cement composition;
After the coating material application step, a sealing material application step of applying a sealing material to a surface other than the predetermined surface of the substrate;
an accelerated weather resistance test step of performing an accelerated weather resistance test using the substrate after the sealing material application step;
1 is a method for testing a cement composition, characterized by having the following characteristics:
Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

According to the present invention, it is possible to perform an accelerated weathering test under conditions close to actual use.

It is a schematic perspective view showing the shape of mortar board 1 of this embodiment. 1 is a schematic perspective view showing a mortar test specimen 10. FIG. It is a figure showing the outline process of preparation of mortar test object 10. It is a figure showing the outline process of an accelerated weathering test and an accelerated carbonation test. FIG. 2 is a diagram showing cut locations of mortar test piece 10 in an accelerated carbonation test. FIG. 3 is a diagram showing the relationship between accelerated material age and carbonation depth without accelerated weathering test. It is a figure showing the relationship between accelerated material age and carbonation depth with accelerated weathering test (1500 hours). FIG. 3 is a diagram showing the relationship between accelerated material age and carbonation rate coefficient without accelerated weathering test. It is a figure showing the relationship between accelerated material age and carbonation rate coefficient with accelerated weathering test (1500 hours). It is a figure showing the transition of the carbonation depth by accelerated weathering test. It is a figure showing the transition of the carbonation rate coefficient by accelerated weathering test. It is a figure showing the transition of the carbonation rate by accelerated weathering test. It is a flow diagram showing an example of a building life prediction method. FIG. 3 is a diagram showing the relationship between acceleration time of weather resistance test and carbonation rate coefficient. FIG. 3 is a flow diagram showing another example of a method for predicting building lifespan. FIG. 3 is a diagram showing the relationship between acceleration time of weather resistance test and carbonation rate.

From the description of this specification and the attached drawings, at least the following matters will become clear.

A covering material application step of applying a covering material to a predetermined surface of a substrate formed of a cement composition; and a sealing material application step of applying a sealing material to a surface other than the predetermined surface of the substrate after the coating material application step. and an accelerated weathering test step of performing an accelerated weathering test using the substrate after the sealing material application step.

According to such a testing method for a cement composition, it is possible to conduct an accelerated weathering test under conditions close to actual use.

In this test method for a cement composition, the substrate is prepared by casting the cement composition in a formwork and curing it in a sealed manner from the first day to the third day of the material age, and After removing the formwork on the third day of age, it is desirable that standard curing is performed until the seventh day of age.

According to such a test method for cement compositions, a substrate is prepared with a thickness that can be tested with an accelerated weathering test machine (e.g., 20 mm as a thickness that prevents the test specimen from falling from the holder during the test). be able to.

In such a method for testing a cement composition, it is desirable that after the standard curing, a bubble filling treatment is performed by rubbing cement paste onto the predetermined surface.

According to such a test method for a cement composition, air bubbles on a predetermined surface can be eliminated.

In such a method for testing a cement composition, it is preferable that after the standard curing, air curing is further performed for a predetermined period, and the step of applying the covering material is performed during the predetermined period.

According to such a cement composition testing method, the coating material can be reliably applied to the substrate.

In this method of testing a cement composition, it is preferable that the step of applying the covering material is performed after confirming that the moisture content of the substrate is 8% or less.

According to such a cement composition testing method, the coating material can be reliably applied to the substrate.

The method for testing such a cement composition preferably further includes an accelerated carbonation test step of conducting an accelerated carbonation test using the substrate after the accelerated weathering test step.

According to such a cement composition testing method, the accuracy of the accelerated carbonation test can be improved.

Further, the test specimen used in the accelerated weathering test includes a substrate formed of a cement composition, a coating material applied to a predetermined surface of the substrate, and a coating material applied to a surface other than the predetermined surface of the substrate. A test specimen characterized by having a sealing material and

According to such a test specimen, an accelerated weathering test can be conducted under conditions close to actual use.

===Embodiment===
EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the structure according to the present invention will be described in detail using the drawings.

≪Overview≫
Generally, in order to measure the carbonation rate of concrete, mortar, etc. in a short period of time, an accelerated carbonation test device is used to conduct an accelerated carbonation test under environmental conditions with a high carbon dioxide concentration. Similar accelerated carbonation tests are also conducted for concrete (or mortar) that has a surface finish that inhibits carbonation.

However, accelerated carbonation testing alone may yield test results that are significantly different from exposure tests in natural environments. For example, surface finishing materials (hereinafter simply referred to as finishing materials) may deteriorate more quickly than concrete due to sunlight's ultraviolet rays or rainfall, or the carbonation suppression effect may change over time. In such cases, accelerated carbonation testing alone may yield test results that are significantly different from exposure tests in the natural environment. In addition, an accelerated weathering test is performed by applying a finishing material to a thin plate (plastic plate or steel plate), and then the deteriorated finishing material is peeled off and applied to a concrete test specimen to perform an accelerated carbonation test. is also being carried out. Even in this case, the finishing material and the concrete test specimen do not adhere completely (different from the state of the actual concrete surface), so accurate evaluation may not be possible.

Therefore, in the present embodiment, an accelerated weathering test is conducted using a mortar test piece that has been given a finishing material. This makes it possible to conduct weather resistance tests under conditions close to those in actual use. After that, an accelerated carbonation test was conducted.

≪Preparation of mortar substrate≫
FIG. 1 is a schematic perspective view showing the shape of a mortar substrate 1 of this embodiment. The mortar substrate 1 was a flat test specimen with a shape of 150×70×20 mm (L in FIG. 1 is 150 mm, H is 70 mm, and W is 20 mm).

Further, Table 1 shows the materials used for the mortar substrate 1 of this embodiment, and Table 2 shows the mortar formulation. In this embodiment, the mortar substrate 1 uses ordinary Portland cement, and the composition is W/C=65%, 1:3.5 mortar. The surface of the fine aggregate was dry and saturated with water.

モルタルは、１バッチを10Lとし、２バッチ分を練り混ぜた。モルタルの練混ぜは、JIS R 5201：2015「セメントの物理試験方法」の「11.5.2練混ぜ方法」に準じて行った。具体的には、モルタルの練混ぜは、JIS R 5201に従って、公称容量20Lの機械式練混ぜ機により行った。

One batch of mortar was 10L, and two batches were mixed. The mortar was mixed in accordance with ``11.5.2 Mixing method'' of JIS R 5201:2015 ``Physical test methods for cement.'' Specifically, the mortar was mixed in accordance with JIS R 5201 using a mechanical mixer with a nominal capacity of 20 L.

First, a specified amount of water (including chemical admixtures) was poured into a kneading pot, and then cement was added. Thereafter, the mixer was started at low speed (rotation speed: 140±5 revolutions per minute, revolution speed: 62±5 revolutions per minute). 30 seconds after starting the paddle, a specified amount of fine aggregate was added in 30 seconds. Next, the kneading was continued at high speed (rotation speed: 285±10 revolutions per minute, revolution speed: 125±10 revolutions per minute) for 30 seconds. Mixing was paused for 90 seconds and scraping was performed during the first 15 seconds of the pause. After the pause, the mixture was started again at high speed and mixed for 60 seconds. After the kneading was completed, the mixture was stirred 10 times with a spoon.

The mortars of the first and second batches were placed in a kneading bowl of a mechanical mixer with a nominal capacity of 50 L, and mixed at low speed for 30 seconds. After kneading, the mixture was stirred 10 times with a spoon, and then a fresh property test was conducted.

To form the mortar substrate 1, mortar was divided into two layers and packed into a mold having a pattern as shown in FIG. Compaction was performed using a ram and a mallet.

≪Preparation of mortar test specimen≫
FIG. 2 is a schematic perspective view showing the mortar test piece 10. FIG. 3 is a diagram showing a schematic process for producing the mortar test body 10.

The mortar packed in the formwork (mortar substrate 1) was sealed and cured until the age of 3 days, and after removing the formwork on the 3rd day of age, standard curing was performed until the age of 7 days. As a result, a mortar substrate 1 having a small thickness (here, 20 mm) could be produced without cracking. Note that sealing curing is not limited to the third day of wood age. For example, the material may be sealed and cured until the first day of material age, and the formwork may be removed on the first day of material age. Furthermore, after standard curing, air curing was performed in a constant temperature and humidity room at 20° C. and 60% RH until the 35th day of material age (that is, 4 weeks (corresponding to the specified period)). On the day after the standard curing was completed, a cement paste with a W/C ratio of 65% was rubbed onto a predetermined surface of the mortar substrate 1 (hereinafter referred to as application surface 1A) to fill in air bubbles on the surface of the test piece. This made it possible to eliminate air bubbles on the coating surface 1A. The coated surface 1A is a surface to which a clear paint 2, which will be described later, is applied, and is also a surface to be exposed in the accelerated weathering test.

Moreover, clear paint 2 (corresponding to the coating material) was applied for 3 days from 2 weeks after air curing (specifically, the 21st day of material age) (corresponding to the coating material construction step). A short bristled non-foam roller was used to apply clear paint 2. In this embodiment, a finishing roller with an outer diameter of 27 mm, a total length of 100 mm, a bristle length of 6 mm, and a bristle material of polyester was used as the non-foam roller.

In addition, the moisture content of the mortar substrate 1 immediately before application of the clear paint 2 was measured using a concrete mortar moisture meter manufactured by Kett Scientific Research Institute, and it was determined that the moisture content was 8% or less, which did not inhibit the adhesion performance of the clear paint. confirmed. In this embodiment, as a result of measurement set in mortar mode, the average was 5.5% (8% or less). Thereby, the clear paint 2 can be reliably applied to the mortar substrate 1.

During coating, the mortar substrate 1 was placed so that the coating surface 1A was horizontal, and the clear paint 2 was applied to the coating surface 1A using a non-foam roller. In addition, the remaining 5 surfaces to which clear paint 2 is not applied (that is, surfaces other than coated surface 1A) are sealed by applying epoxy resin 3 (equivalent to sealing material) between the 28th and 35th days of the material's age. (equivalent to the sealant installation step).

≪About mortar test items≫
Table 3 shows the mortar test items. Fresh property tests were conducted by taking samples immediately after kneading. The test items were 0 stroke flow, 15 stroke flow, air volume, and mortar temperature as shown in the table.

Regarding the hardening properties, a compressive strength test was conducted. As with mortar substrate 1, the specimen for compressive strength was demolded on the third day of age. The standard cured specimens were tested on the 7th and 28th day of age. On the other hand, the test specimens under the same curing conditions as the flat plate test specimens were tested on the 35th day of material age (the start date of the accelerated neutralization test or the accelerated weathering test).

≪クリヤ塗料の構成と塗布量について≫
今回の実験で使用したクリヤ塗料の概要を表４に示す。いずれの銘柄も水系のクリヤ塗料である。Ａ社製の中塗り材は、顔料入りと顔料なしの２種類がある。Ｂ社製は、顔料入りの仕様のみであり、Ｃ社製は、顔料なしの仕様である。なお、上塗り材は、いずれも顔料なしの使用である。

≪About the composition and application amount of clear paint≫
Table 4 shows an overview of the clear paints used in this experiment. Both brands are water-based clear paints. There are two types of intermediate coating materials manufactured by Company A: one with pigment and one without pigment. The product manufactured by Company B only has a pigment-containing specification, and the product manufactured by Company C has a specification without a pigment. Incidentally, all of the top coating materials were used without pigment.

モルタル基板１に塗布したクリヤ塗料２の材料構成と塗布量を表５および表６に示す。なお、表５は、促進耐候性試験を行わない場合の試験体を示し、表６は、促進耐候性試験を行なう場合の試験体を示している。各表に示すように、試験体Ｎｏ.１は、クリヤ塗料２を塗布しない試験体（比較例）であり、試験体Ｎｏ.２～Ｎｏ.８は、クリヤ塗料２を塗布する試験体である（実施例）。

Tables 5 and 6 show the material composition and coating amount of the clear paint 2 applied to the mortar substrate 1. Note that Table 5 shows the test specimens when the accelerated weathering test is not performed, and Table 6 shows the test specimens when the accelerated weathering test is performed. As shown in each table, test specimen No. 1 is a test specimen not coated with clear paint 2 (comparative example), and test specimens No. 2 to No. 8 are test specimens coated with clear paint 2. (Example).

Specimen No. 1b (Table 6) to be subjected to the accelerated weathering test was tested by covering the entire body with an aluminum bag and sealing it to prevent the exposed surface of the mortar from being sprayed with water during the test. After the accelerated weathering test was completed, when conducting the accelerated carbonation test, the aluminum bag was removed and the test was conducted.

≪Accelerated weathering test and accelerated neutralization test≫
FIG. 4 is a diagram showing a schematic process of an accelerated weathering test and an accelerated carbonation test. As shown in the figure, accelerated carbonation tests were conducted on mortar specimens coated with clear paint, and the effects of differences in the material composition and application amount of clear paint on mortar's neutralization suppression effect were quantitatively confirmed. did.

Accelerated carbonation tests are conducted after one week of standard curing and four weeks of air curing after mortar placement, and after one week of standard curing, four weeks of air curing, and accelerated weathering test. Two cases were conducted to confirm the influence of deterioration of the coating film itself of Clear Paint 2 on the neutralization suppressing effect. A sunshine carbon arc lamp type weather resistance tester was used as the accelerated weather resistance tester. The test time of the accelerated weathering test was set to three levels: 1500 hours, 3000 hours, and 5000 hours. The respective test times correspond to 6, 12, and 20 years of outdoor exposure (see Architectural Institute of Japan Structural Engineering Transactions, No. 584, pp. 15-21, October 2004).

<Accelerated weathering test>
The accelerated weathering test was conducted using a sunshine weather meter that satisfies the standards of JIS B 7753:2007 "Sunshine carbon arc lamp type light resistance tester and weatherability tester". Table 7 shows an overview of the sunshine weather meter. The test conditions are JIS K 7350-4: 2008 "Plastics - Exposure test method using laboratory light source - Part 4: Open frame carbon arc lamp" and JIS A 1415: 1999 "Exposure of polymeric building materials using laboratory light source". Test method. Further, the spray conditions are shown in Table 8. As shown in Table 8, "spray cycle 1" of "6.3 spray conditions" of JIS K 7350-4 was used. As mentioned above, the test times were 1500 hours, 3000 hours, and 5000 hours, assuming 6 years, 12 years, and 20 years of exposure.

In addition to the Sunshine carbon arc lamp type (JIS B 7753:2007), accelerated weathering testers that are compliant with JIS standards include the following.
JIS B 7751:2007 Ultraviolet carbon arc lamp type light resistance tester and weather resistance tester
JIS B 7754:1991 Xenon arc lamp type light resistance and weather resistance tester
In any of the test machines, if the thickness of the test piece is too large, the distance from the light source of the test machine becomes too short and the test piece deteriorates quickly, so there is a limit to the thickness that can be tested. Specifically, in order to prevent the test specimen from falling from the holder during the test, the thickness must be limited to about 2 cm (20 mm). In this embodiment, the thickness of the test specimen (mortar test specimen 10) is set to 20 mm, so that the accelerated weathering test can be performed using the above-mentioned testing machine.

In addition, the following JIS standards are available for testing methods.
JIS A 1415:2013 Exposure test method using laboratory light source for polymeric building materials
JIS K 7350-1: 1995 Plastics - Exposure test method using laboratory light source Part 1: General rules
JIS K 7350-2:2008
Plastics - Exposure test method using laboratory light source - Part 2: Xenon arc lamp
JIS K 7350-3:2008
Plastics - Exposure test method using laboratory light source - Part 3: Ultraviolet fluorescent lamp In addition, the following JIS standards exist as an accelerated weathering test method for paints.
JIS K 5600-7-7 Accelerated weather resistance and accelerated light resistance (xenon lamp method)
JIS K 5600-7-8 Accelerated weathering (ultraviolet fluorescent lamp method)

<Accelerated carbonation test>
An accelerated neutralization test of the mortar test piece 10 coated with the clear paint 2 was conducted in accordance with JIS A 1153. The test material ages were 1 week, 4 weeks, 8 weeks, 13 weeks, and 26 weeks, and the mortar test specimen 10 was cut at each material age to measure the carbonation depth. FIG. 5 is a diagram showing cut locations of the mortar test piece 10 in the accelerated carbonation test. In addition, in FIG. 5, illustration (hatching) of the clear paint 2 and the epoxy resin 3 is omitted. Further, each cut surface of the mortar test specimen 10 was sealed with epoxy resin.

≪Test results≫
<Fresh properties>
The fresh property test was conducted immediately after the first batch was kneaded and immediately after the first and second batches were combined. Table 9 shows the results of the fresh property test. The air amount satisfied the target value of 4.5±1.5%.

＜モルタルの硬度性状＞
モルタルの圧縮強度の試験結果を表１０，表１１に示す。モルタル平板試験体と同じ養生条件とした供試体の材齢35日の圧縮強度は22.6Ｎ/mm^２であった。なお、モルタル平板試験体の促進中性化試験および促進耐候性試験は、材齢35日より開始した。この結果より、圧縮強度には特に問題がないことを確認した。

<Hardness properties of mortar>
Tables 10 and 11 show the test results of mortar compressive strength. The compressive strength of the 35-day-old specimen under the same curing conditions as the mortar flat plate specimen was 22.6 N/mm ² . The accelerated carbonation test and accelerated weathering test of the mortar flat plate specimens were started from the age of 35 days. From this result, it was confirmed that there were no particular problems with compressive strength.

<Neutralization depth>
FIGS. 6 and 7 are diagrams showing the relationship between accelerated material age and carbonation depth. Note that FIG. 6 shows the results without accelerated weathering test (weathering test 0 hours), and FIG. 7 shows the results with accelerated weathering test (weathering test 1500 hours). In Figure 6, the test specimens coated with clear paint (test specimens No. 2 to 8) have a greater depth of carbonation than the uncoated specimen (test specimen No. 1) at the same material age. (neutralization suppressing effect). Furthermore, at 26 weeks of accelerated material age, the neutralization depth of the uncoated specimen almost reached the thickness of the mortar specimen (20 mm), but in the specimen coated with clear paint, it was less than 5 mm. be. Almost the same tendency can be seen in FIG. 7 as well. Further, in FIG. 7, the depth of carbonation of specimen No. 1b to which no clear paint was applied (with seal) was smaller than that of specimen No. 1a (without seal) to which no clear paint was applied.

<Neutralization rate coefficient>
FIGS. 8 and 9 are diagrams showing the relationship between accelerated material age and carbonation rate coefficient. Note that FIG. 8 shows the results without accelerated weathering test (weathering test 0 hours), and FIG. 9 shows the results with accelerated weathering test (weathering test 1500 hours). The test specimens coated with clear paint (test specimen No. 2 to No. 8) had a smaller neutralization rate coefficient than the test specimen to which no clear paint was applied (test specimen No. 1).

<Changes in carbonation depth, carbonation rate coefficient, and carbonation rate by accelerated weathering test>
FIG. 10 is a diagram showing the transition of carbonation depth by accelerated weathering test, FIG. 11 is a diagram showing the transition of carbonation rate coefficient by accelerated weathering test, and FIG. 12 is a diagram showing transition of carbonation depth by accelerated weathering test. FIG. 3 is a diagram showing the transition of carbonation rate according to a carbonation test. Note that the carbonation rate is the ratio of the carbonation depth of concrete with a finishing material applied to the carbonation depth of concrete without a finishing material (see equation 5 below) (Japanese Architecture Academic Society: Building Work Standard Specifications and Commentary (from JASS5 Reinforced Concrete Construction). The horizontal axis of each of these figures is the test time of the accelerated weathering test.

As shown in the figure, even after 3000 hours of weather resistance test (equivalent to 12 years of exposure), neutralization was suppressed in the test specimen coated with clear paint.

≪About building lifespan prediction (prediction method 1)≫
FIG. 13 is a flow diagram illustrating an example of a method for predicting the lifespan of a building. Here, the building life is predicted using the carbonation rate coefficient.

First, as shown in FIG. 13, a finished test specimen is prepared (S101). In this embodiment, the finished test specimens are mortar test specimens 10 (test specimens No. 2 to No. 8) in which the clear paint 2 is applied to the coating surface 1A of the mortar substrate 1.

Next, an accelerated weathering test is performed using the test specimen (S102: corresponds to the accelerated weathering test step). This accelerated weathering test causes the finishing material (here, clear paint 2) on the surface of the test piece to deteriorate. The period of deterioration is defined as multiple points (multiple periods). For example, using a sunshine carbon arc lamp type weather resistance tester specified in JIS B 7753:2007, JIS K 7350-4:2008 "Plastics - Exposure test method using laboratory light source - Part 4: Open frame carbon" Arc lamp" and JIS A 1415: 2013 "Exposure test method using laboratory light source for polymeric building materials", 250 hours of accelerated testing is equivalent to one year of outdoor exposure in the Kanto area. It has been known. Here, accelerated weathering tests are performed for three periods (1500 hours, 3000 hours, and 5000 hours) (equivalent to 6 years, 12 years, and 20 years of outdoor exposure, respectively).

Next, an accelerated carbonation test is performed using the specimen subjected to the accelerated weather resistance test (S103: corresponds to the accelerated carbonation test step). That is, an accelerated carbonation test is performed on a specimen whose finishing material has deteriorated due to the accelerated weathering test. The carbonation depth is measured at accelerated material ages of 1 week, 4 weeks, 8 weeks, 13 weeks, and 26 weeks in accordance with JIS A 1153:2012 ``Concrete accelerated carbonation test method''. Alternatively, measurements may be made at other accelerated material ages of 26 weeks or less. If the carbonation depth reaches the thickness of the specimen (20 mm) or more at accelerated material age up to 26 weeks, use the measured value of the carbonation depth before 26 weeks to calculate the carbonation depth at the 26th week using the least squares method. All you have to do is estimate the carbonation depth.

Further, from the measured value (or estimated value) of the carbonation depth, a carbonation rate coefficient A that changes over time is determined from the following (Equation 1) (S104).

C=A√t...(Formula 1)
C: Neutralization depth (mm)
A: Carbonation rate coefficient (mm/√week)
t: accelerated material age (weeks)
(From Architectural Institute of Japan: Architectural Work Standard Specifications and Commentary JASS5 Reinforced Concrete Construction (2018))
Specifically, from the relationship between the acceleration time of the weather resistance test at multiple points (elapsed time of outdoor exposure) and the carbonation rate coefficient A, the curve formula of the change over time of the carbonation rate coefficient or A linear equation (a function with the material age T in the natural environment as a variable) is determined. FIG. 14 is a diagram showing the relationship between the acceleration time of the weather resistance test and the carbonation rate coefficient. In FIG. 14, the neutralization rate coefficients are determined for each of the three promotion times, and a regression curve or regression line is determined from the data of a plurality of stores by the least squares method. Thereby, the neutralization rate coefficient A at any material age can be estimated.

The accelerated carbonation test will be conducted in an environment with a temperature of 20°C, relative humidity of 60% RH, and a CO ₂ concentration of 5.0% (on the other hand, the CO ₂ concentration in the natural environment is approximately 0.05% outdoors and indoors However, a value of around 0.10% to 0.20% is generally used). Thus, an accelerated neutralization test is conducted in an environment with high CO ₂ concentration.

Next, a coefficient β ₁ due to the temperature in the natural environment, a coefficient β ₂ due to the influence of humidity and moisture acting on concrete, and a coefficient β ₃ due to the CO ₂ concentration are determined (S105).

Then, the material age T (weeks) at which the carbonation depth C reaches the covering thickness of the reinforcing bars in a natural environment is determined (S106).

First, the carbonation rate coefficient _A1 in actual exposure in a natural environment is determined using the following (Equation 2).

A ₁ =k・α ₁・α ₂・α ₃・β ₁・β ₂・β ₃ (Formula 2)
A ₁ : Carbonation rate coefficient in actual exposure under natural environment (mm/√year)
k: Constant related to carbonation rate (mm/√year)
α ₁ : Coefficient due to concrete type (type of aggregate) α ₂ : Coefficient due to cement type α ₃ : Coefficient due to mixture (water-cement ratio) β ₁ : Coefficient due to temperature β ₂ : Coefficient due to humidity and moisture acting on concrete Coefficient due to influence β ₃ : Coefficient due to CO ₂ concentration (from Architectural Institute of Japan: Durability Design and Construction Guidelines for Reinforced Concrete Buildings and Commentary (2016))

The coefficient k related to carbonation rate, the coefficient α _{1 depending on the type of concrete (type of aggregate),} the coefficient α _{2 depending on the type of cement, and} the coefficient α ₃ depending on the mixture (water-cement ratio) have already been reflected in the accelerated carbonation test. has been done. Note that the coefficient k related to the carbonation rate also includes a coefficient due to the influence of finishing. Therefore, the carbonation rate coefficient A obtained by the accelerated carbonation test can be converted into the carbonation rate coefficient _A1 in actual exposure using the following (Equation 3).

Furthermore, when calculating the carbonation depth in a natural environment using the carbonation rate coefficient obtained in the accelerated carbonation test, (Equation 4) can be obtained by considering β _1, β _2, β ₃ . can get.

C=A・β ₁・β ₂・β _3・√T (Formula 4)
C: Neutralization depth (mm)
A: Carbonation rate coefficient (mm/√week)
β ₁ : Coefficient due to temperature β ₂ : Coefficient due to the influence of humidity and moisture acting on concrete β ₃ : Coefficient due to CO ₂ concentration T: Age of material (weeks)

The carbonation depth C at multiple points of material age T is calculated using (Equation 4), and plotted, for example, on a graph in which the horizontal axis represents the material age T and the vertical axis represents the carbonation depth C. Then, a regression curve or regression line of the relationship between the material age T and the neutralization depth C is determined by the least squares method or the like. Using this regression equation, the material age T at which the neutralization depth C reaches the reinforcing steel cover thickness is determined (S106). This makes it possible to predict the lifespan of the building.

As explained above, in this embodiment, the clear paint 2 is applied to the application surface 1A of the mortar substrate 1, and then the mortar test specimen 10 whose surfaces other than the application surface 1A are sealed with the epoxy resin 3 is used to provide accelerated weathering. Conducting a sex test. This makes it possible to perform weather resistance tests under conditions close to those of actual use, thereby increasing the accuracy of carbonation evaluation and building life prediction.

≪About building lifespan prediction (prediction method 2)≫
FIG. 15 is a flow diagram illustrating another example of a building life prediction method. Here, the carbonation rate is used to predict the building life.

First, as shown in FIG. 15, a finished specimen and an unfinished specimen are prepared (S201). In this embodiment, the finished test specimens are the mortar test specimens 10 (test specimens No. 2 to 8) in which the clear paint 2 is applied to the coating surface 1A of the mortar substrate 1, and the unfinished test specimens are is a test specimen (test specimen No. 1) in which the clear paint 2 was not applied to the mortar substrate 1.

Next, an accelerated weathering test is performed using each specimen (S202). The accelerated weathering test is the same as step S102 in FIG. 13, so the explanation will be omitted.

Next, an accelerated neutralization test is performed using the specimen that has undergone the accelerated weathering test (S203). The accelerated carbonation test is also the same as step S103 in FIG. 13, so the explanation will be omitted.

Next, from the measured value (or estimated value) of the carbonation depth for 26 weeks, the carbonation rate that changes over time is determined from the following (Equation 5) (S203).

Neutralization rate=c ₁ /c ₂ (Formula 5)
c ₁ : Carbonation depth of finished concrete c ₂ : Carbonation depth of unfinished concrete Acceleration time of multiple points weather resistance test (elapsed time of outdoor exposure) and carbonation rate From the relationship, a curved expression or linear expression (a function using the material age T in the natural environment as a variable) of the change over time of the carbonation rate is determined by the least squares method. FIG. 16 is a diagram showing the relationship between the acceleration time of the weather resistance test and the carbonation rate. Even in this case, the carbonation rate at any age can be estimated from data at multiple points.

Next, the lifespan of the building is predicted using the carbonation rate. Here, we first use (Equation 6) from the existing literature (Concrete Engineering Annual Proceedings, Vol. 28, No. 1, 2006, pp. 665-670) to The sexualization rate coefficient _A0 is determined (S204). Then, by multiplying the right side of (Equation 7) by the carbonation rate (c ₁ /c ₂ ) that changes over time, the carbonation depth of finished concrete can be calculated as shown in (Equation 8). The value _C1 is calculated.

A ₀ =23.8(1/√f−0.13) ・・・・・・(Formula 6)
C=A ₀ √T (Formula 7)
C: Depth of carbonation of concrete (unfinished) when exposed outdoors (mm)
A ₀ : Carbonation rate coefficient (mm/√year) determined from existing literature
f: Compressive strength of standard cured specimen at 28 days old (N/mm ² )
T: Material age (years)

C ₁ =c ₁ /c ₂ ×A ₀ √T (Formula 8)
C ₁ : Depth of carbonation of finished concrete exposed outdoors (mm)
c ₁ : Carbonation depth of finished concrete (measured value of accelerated carbonation test)
_c2 : Carbonation depth of unfinished concrete (measured value of accelerated carbonation test)
Also here, the carbonation depth C ₁ at multiple points of material age may be calculated using (Equation 8), and a regression curve or regression line of the relationship between material age T and carbonation depth C ₁ may be obtained. From this regression equation, the material age T at which the neutralization depth _C1 reaches the reinforcing steel cover thickness is determined (S206). This allows the lifespan of the building to be predicted.

In addition, if the carbonation rate coefficient of unfinished concrete is already known, the right side of the above (Equation 1) can be multiplied by the carbonation rate (c ₁ /c ₂ ) that changes over time. , it is possible to predict the age at which the carbonation depth reaches the reinforcing steel, that is, the life of the building.

Even when the carbonation rate is used in this way, it is possible to improve the accuracy of evaluation of carbonation (such as prediction of building life), as in the case where the carbonation rate coefficient is used. In addition, when using this carbonation rate, the coefficients when using the carbonation rate coefficient (coefficient β ₁ due to temperature, coefficient β _{2 due to the influence of humidity and moisture acting on concrete,} coefficient β ₃ due to CO ₂ concentration) ), and can be easily evaluated.

===Other embodiments===
The embodiments described above are provided to facilitate understanding of the present invention, and are not intended to be interpreted as limiting the present invention. It goes without saying that the present invention may be modified and improved without departing from its spirit, and that the present invention includes equivalents thereof.

In the embodiment described above, the mortar substrate 1 was used, but the substrate may be made of other cement compositions (for example, concrete).

In the embodiment described above, the clear paint 2 was applied to the application surface 1A of the mortar substrate 1, but the present invention is not limited to this, and other coating materials may be provided. For example, finishing materials such as resin coating, resin film, tiles, and stone may be applied.

Furthermore, in the above-described embodiment, the surfaces (5 surfaces) other than the application surface 1A of the mortar substrate 1 were sealed by applying epoxy resin, but the present invention is not limited to this, and other sealing materials may be applied. Good too.

1 Mortar substrate 1A Coating surface (predetermined surface)
2 Clear paint (coating material)
3 Epoxy resin (sealing material)
10 Mortar test specimen

Claims (7)

A covering material construction step of constructing a resin film, tile, or stone as a covering material on a predetermined surface of a substrate formed of a cement composition;
After the coating material application step, a sealing material application step of applying a sealing material to a surface other than the predetermined surface of the substrate;
an accelerated weather resistance test step of performing an accelerated weather resistance test using the substrate after the sealing material application step;
A method for testing a cement composition, comprising: A method for testing a cement composition according to claim 1, comprising:
The substrate was prepared by pouring the cement composition into a formwork and curing it in a sealed manner from the first day to the third day of age, and removing the formwork from the first day to the third day of age. After that, standard curing is performed until the 7th day of wood age.
A method for testing a cement composition, characterized by: A method for testing a cement composition according to claim 2, comprising:
After the standard curing, a cement paste is rubbed into the predetermined surface to perform a bubble filling process. A method for testing a cement composition according to claim 2 or 3, comprising:
After the standard curing, further air curing is performed for a predetermined period,
performing the covering material construction step during the predetermined period;
A method for testing a cement composition, characterized by: A method for testing a cement composition according to any one of claims 1 to 4, comprising:
The coating material construction step is performed after confirming that the moisture content of the substrate is 8% or less,
A method for testing a cement composition, characterized by: A method for testing a cement composition according to any one of claims 1 to 5, comprising:
further comprising an accelerated carbonation test step of performing an accelerated carbonation test using the substrate after the accelerated weathering test step;
A method for testing a cement composition, characterized by: A test specimen used in an accelerated weathering test,
a substrate formed of a cement composition;
A resin film, tile, or stone as a covering material applied to a predetermined surface of the substrate;
a sealing material applied to a surface other than the predetermined surface of the substrate;
A test specimen characterized by having.

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