JP2938417B2 - Specimen capping device for concrete or mortar compressive strength test and compressive strength test method for concrete and mortar - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capping device in a concrete and mortar compressive strength test device, and more particularly to a concrete or mortar capable of performing a high-precision compressive strength test easily, in a short time and at low cost. The present invention relates to a capping device in a mortar compressive strength test device.

[0002]

2. Description of the Related Art Conventionally, the compressive strength test of concrete has
For example, the upper surface of a specimen prepared according to the preparation procedure specified in Jls A 1132 “How to prepare a specimen for strength testing of concrete” is formed (capping), and this specimen (JISA1107 “Core from concrete”) is formed. JIS A 1108, including specimens prepared in accordance with the procedures specified in “Methods for Cutting Beams and Beams and Testing Methods for Strength”).
In the compression test apparatus according to the above, and apply a compression load to the specimen. According to this provision, the specimen
It is created by the following steps (1) to (5). (1) The pressing plate used for capping is polished glass or polished steel plate, has a thickness of 6 mm or more, and has a size 25 mm or more larger than the diameter of the mold. (2) The upper surface of the concrete specimen shall be finished in a plane perpendicular to the axis of the concrete specimen. The finished surface must not be more than 0.05mm uneven. (3) When capping with cement paste,
After filling the concrete, at an appropriate time (2-6 hours for Kata-kneaded concrete, 6-
After removing fine particles and latencies on the upper surface (24 hours), the plate is washed with water, wiped off with water, and then poured with cement paste, and pressed uniformly to the top surface of the mold with a pressing plate. (4) Cement paste (water / cement weight ratio 27-3)
(0%) is kneaded 2 to 4 hours before use, and kneaded without adding water. (5) To prevent the pressing plate from sticking to the cement paste, apply oil to the upper surface of the pressing plate or insert thin paper such as paraffin paper.

In addition, according to the method specified in JLSA 1132, in order to reduce the shrinkage of the cement paste, it is necessary to knead the mixture 2 to 4 hours before pouring and to knead the mixture without adding water. . For this reason, the compressive strength test of concrete required a great deal of labor and time.

[0004] Further, regarding mortar, JIS A
According to 5308 and 1132, a method of preparing a test piece is specified. According to this method, it is necessary to polish the upper surface of the test piece immediately before the compression test. Needed time and.

[0005] As another method of preparing a specimen, there is a method described in Australian Standard Reference AS 1012.9-1986 (method for measuring compressive strength of concrete specimen). As shown in FIG. 3, the capping device 23 includes a steel concave cap member 21 and a natural rubber plate having a thickness of 13 to 15 mm and a Shore A hardness of 50.
Some use. Then, the capping device 23 is installed on the capping surface 25 of the concrete specimen 26 with the capping surface 25 facing downward, and a compressive strength test is performed. When the compressive strength test is performed, the rubber plate 2 of the jig can alleviate the unevenness on the lower surface of the concrete specimen 26 and can evenly apply a load.

[0006]

However, when a compressive strength test is performed by using the above capping method, there is a problem that a rubber plate does not enter between the jig and the concrete specimen during loading and cannot pass through.

Further, according to the Australian standard, since the concrete is brought into direct contact with the rubber plate and loaded with a high compressive force, the rubber plate may be deteriorated and cracked or damaged. If the rubber plate is damaged or cracked in this way, a predetermined compressive force does not act on the specimen, and the compressive strength of concrete cannot be measured accurately. For this reason, this standard stipulates that the use limit of the rubber plate should be visually checked for tears or cracks, and that when a break or crack is found, the rubber plate be replaced as a limit of use. ing.

However, according to this standard, the quality of a rubber plate is visually inspected. Therefore, the judgment is not constant, is poor in objectivity, and is measured by an inspector using a deteriorated rubber plate. There is a problem that the reliability of the measured value of the compressive strength of concrete is not high.

Accordingly, the present invention provides a concrete or mortar compressive strength test apparatus capable of easily performing a high-accuracy compressive strength test capable of obtaining a measurement result equivalent to the conventional JIS standard in a short time and at low cost. An object of the present invention is to provide a capping device.

[0010]

Means for solving the above-mentioned problems in the present application are as follows.

According to the first aspect of the present invention, there is provided a pressing portion 2 having a flat plate shape, and an annular portion formed on the lower surface of the pressing portion 2 and having an inner diameter slightly larger than the outer diameter of the specimen 4. 3. A concrete or mortar compressive strength test apparatus comprising a steel cap member 1 made of a rubber material 3 and a rubber pad material 5 arranged between the upper surface of the test piece 4 and the pressing portion 2 of the cap member 1. In the capping device, the pad material 5 is a chloroprene rubber or polyurethane rubber plate material having a constant thickness and the same diameter as the inner diameter of the annular portion 3 of the cap member 1. The rubber hardness at the time of initial use is a predetermined hardness, and the rubber hardness measured by a rubber hardness meter at the time of use is a decrease within a predetermined amount from the rubber hardness at the time of initial use. Anti The elasticity is a value in a predetermined range predetermined for chloroprene rubber or polyurethane rubber, respectively, and the specific gravity when the pad material 5 is used is a value in a predetermined range for chloroprene rubber or polyurethane rubber, respectively. This is a capping device in a concrete or mortar compressive strength test device, which has been confirmed.

According to a second aspect of the present invention, the pad material 5 according to the first aspect has a thickness of 10 mm, a rubber hardness of 60 ± 5 degrees (JIS K6301) when initially used, and This is a capping device in a concrete or mortar compressive strength test device in which the decrease in rubber hardness measured by a rubber hardness meter during use is within 2 degrees.

According to a third aspect of the present invention, the pad material 5 according to the first aspect has a thickness of 10 mm and a rubber hardness of 50 ± 5 degrees (JIS K6301) when initially used, And it is a capping device in a concrete and mortar compressive strength test device in which a decrease in rubber hardness measured by a rubber hardness meter during use is within 2 degrees.

According to a fourth aspect of the present invention, the pad material 5 according to the first aspect has a thickness of 10 mm, a rubber hardness of 65 ± 5 degrees (JIS K6301) at the time of initial use, and This is a capping device in a concrete or mortar compressive strength test device in which the decrease in rubber hardness measured by a rubber hardness meter during use is within 2 degrees.

According to a fifth aspect of the present invention, the pad material 5 according to the first aspect has a thickness of 10 mm, a rubber hardness of 70 degrees (JIS K 6301) at the time of initial use, and It is a capping device in a concrete or mortar compressive strength test device in which the decrease in rubber hardness measured by a rubber hardness meter is within 2 degrees.

According to a sixth aspect of the present invention, the pad material 5 according to the second, third, fourth or fifth aspect is made of chloroprene rubber and has a rebound resilience in use of 53 ± 3%. It is a capping device in a concrete or mortar compressive strength test device having a specific gravity of 1.40 ± 0.03.

According to a seventh aspect of the present invention, the pad material 5 according to the second, third, fourth or fifth aspect is made of polyurethane rubber and has a rebound resilience of 59 ± 3% when used. It is a capping device in a concrete or mortar compressive strength test device having a specific gravity of 1.30 ± 0.03.

[0018] The invention according to claim 8 is a plate-like pressing portion 2.
A steel cap member 1 formed on the lower surface of the pressing portion 2 and having an annular portion 3 having an inner diameter slightly larger than the outer diameter of the specimen 4 and suspended in an annular shape; A compressive load is applied to a specimen by using a capping device 10 including a rubber pad member 5 disposed between the pressing portion 2 of the cap member 1 and concrete or concrete for measuring the compressive strength of the specimen. In the mortar compressive strength test method, the pad material 5 has a constant thickness, the same diameter as the inner diameter of the annular portion 3 of the cap member 1, and the rubber hardness at the time of initial use is a predetermined value. Using a chloroprene rubber or polyurethane rubber plate material that is hardness, measure with a rubber hardness meter at the time of use to confirm that the rubber hardness is within a predetermined amount from the rubber hardness at the time of initial use, and at the time of use It was measured The elasticity is within a predetermined amount range respectively predetermined for chloroprene rubber or polyurethane rubber, and the specific gravity measured at the time of use is within a predetermined amount range respectively predetermined for chloroprene rubber or polyurethane rubber. It is a test method for concrete or mortar compressive strength to be confirmed and loaded on a specimen.

According to a ninth aspect of the present invention, the pad material 5 according to the eighth aspect has a thickness of 10 mm and a rubber hardness of 60 ± 5 degrees (JIS K 6301) when initially used. This is a concrete or mortar compressive strength test method in which the rubber hardness is measured with a rubber hardness meter at the time of use, and the measured decrease in rubber hardness is confirmed to be within 2 degrees.

According to a tenth aspect of the present invention, the pad material according to the eighth aspect has a thickness of 10 mm and a rubber hardness of 50 ± 5 degrees (JIS K6301) at the time of initial use. 9. The concrete or mortar compressive strength test method according to claim 8, wherein said method is used and confirms that a decrease in rubber hardness measured during use is within 2 degrees.

According to an eleventh aspect of the present invention, the pad material 5 according to the eighth aspect has a thickness of 10 mm and a rubber hardness of 65 ± 5 degrees (JIS K 6301) when initially used. This is a concrete or mortar compressive strength test method for confirming that the amount of decrease in rubber hardness measured during use is within 2 degrees.

According to a twelfth aspect of the present invention, the pad material 5 of the eighth aspect has a thickness of 10 mm, a rubber hardness of 70 ± 5 degrees (JIS K6301) at the time of initial use, and This is a concrete or mortar compressive strength test method in which the decrease in rubber hardness measured during use is within 2 degrees.

According to a thirteenth aspect of the present invention, there is provided the pad material according to the ninth, tenth, eleventh or twelfth aspect.
Is made of chloroprene rubber and has a rebound resilience of 53 when used.
It is a concrete or mortar compressive strength test method using a material having a specific gravity of ± 3% and a specific gravity of 1.40 ± 0.03.

According to a fourteenth aspect of the present invention, there is provided a pad material according to the ninth, tenth, eleventh or twelfth aspect.
Is made of polyurethane rubber and has a rebound resilience of 59 when used.
It is a concrete or mortar compressive strength test method using ± 3% and a specific gravity of 1.30 ± 0.03.

According to a fifteenth aspect of the present invention, there is provided a concrete or mortar compressive strength test method according to the ninth, tenth, eleventh, twelfth, thirteenth, or fourteenth aspect. This is a concrete or mortar compressive strength test method in which a concave material formed on an upper surface of a specimen is filled with a particulate substance having a particle size of 0.15 mm or less and a cap member 1 is mounted on the specimen.

According to the present invention, the deterioration of the pad material 5 can be objectively evaluated based on the decrease in rubber hardness measured by a rubber hardness meter, and an appropriate pad material can always be used. Therefore, the reliability of the measured values of compressive strength of concrete and mortar can be increased.

Further, by selecting an appropriate material as the pad material, it is possible to obtain a value equivalent to a value obtained by performing a compressive strength test on a test sample prepared in accordance with JIS A1132.

In the present invention, the thickness of the pad material 5, the initial rubber hardness and the allowable value of the reduction, the rebound resilience, and the specific gravity were determined by conducting a number of experiments on concrete specimens. Based on Jls A 113
2 is determined to be able to obtain a value equivalent to the value (reference value) of a test sample prepared in accordance with 2. Therefore, according to the present invention, for a concrete specimen,
The measurement result equivalent to the JIS standard can be easily obtained in a short time and at a low cost without trouble such as capping with a cement paste.

In this test, the hardness of the pad material 5 was measured by a rubber hardness tester, and the rebound resilience and specific gravity were measured. The reliability of the measured values is high.

Further, according to the present invention, the thickness of the pad material 5 and the initial rubber hardness and the value of the allowable range for the reduction are determined by a number of experiments on concrete specimens of young materials (form removal time). Based on this result, based on this result, the concrete standard specification (hereinafter referred to as the specification) and the building construction standard specification JASS 5 reinforced concrete work (hereinafter referred to as JASS 5)
In the demolding time shown in (1), a value equivalent to the value (reference value) of a specimen prepared in accordance with JIS A 1132 is determined.

Therefore, according to the present invention, the method and the JASS
About the specimen of concrete of the young age shown in 5,
The measurement result equivalent to the JIS standard can be easily obtained in a short time and at low cost without any trouble such as capping with a cement pace.

In this test, since the hardness of the pad material 5, its elasticity, and the specific gravity are measured by a rubber hardness tester, an appropriate pad material can always be used, and the measured value of the compressive strength can be obtained. The reliability is high.

Further, according to the present invention, the thickness of the pad material 5, the initial rubber hardness and the value of the allowable range for reduction are determined by conducting a number of experiments on mortar specimens, and based on the results, JIS A It is determined that a value equivalent to the value (reference value) of a specimen prepared based on 5308, 1805, 1107 and 1132 can be obtained.

Therefore, according to the present invention, the mortar specimen can be used without any trouble such as polishing of the specimen.
Measurement results equivalent to the JIS standard can be easily obtained in a short time and at low cost.

In this test, the hardness of the pad material 5 is measured by a rubber hardness tester, so that an appropriate pad material can always be used, and the reliability of the measured compressive strength is high. Become.

Further, according to the present invention, the thickness of the pad material 5, the initial rubber hardness and the value of the allowable range for reduction are determined by performing a number of experiments on a specimen of high strength mortar. JIS A 5308, 1805, 110
7 and 1132 are determined so as to obtain a value equivalent to the value (reference value) of a specimen prepared in accordance with Nos. 7 and 1132.

Therefore, according to the present invention, it is possible to easily obtain a measurement result equivalent to the JIS standard in a short time and at low cost for a high-strength mortar specimen without any trouble such as polishing of the specimen. it can.

In this test, since the hardness of the pad material 5 was measured by a rubber hardness tester, an appropriate pad material could always be used, and the reliability of the measured compressive strength was high. Becomes

Further, according to the present invention, when a concave portion is present on the upper end surface of the specimen, 0.15
mm or less, place the surface flat, level the surface, and place a capping device on the surface to load the sample uniformly. Can do it.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a capping device in a concrete or mortar compressive strength test device according to the present invention will be described below.

[First Embodiment] A first embodiment of a capping device in a concrete or mortar compressive strength test apparatus according to the present invention will be described below.

The concrete subjected to the test in this example is as follows. The cement is Portland cement with high strength, and fine aggregate is made of river sand from China (called river sand from China) and Kimitsu mountain sand from Chiba prefecture.
A The mixture of the former 59 and the latter 41 was used in a standard particle size range shown in A5308. The coarse aggregate is hard sandstone crushed stone 2005 from Iibuchi, Ibaraki Prefecture. AE water reducing agent mainly composed of lignin sulfonate as an admixture, and A
E auxiliaries were used.

As shown in FIGS. 1 and 2, the capping device has a rubber cap member 1 attached to a steel cap member 1. The material of the cap member 1 is S
KS steel, which is quenched and finished, and is formed on a flat pressing portion 2 (plate pressure t ₁ = 13 mm) and a lower surface of the pressing portion 2 and has an outer diameter (D = 100m
m) and an annular portion 3 (plate pressure t ₀ = 11 mm, height t ₂ = 20 mm) suspended in an annular shape with an inner diameter (d ₀ = 102 mm) slightly larger than these cap members 1.
Was made according to ASTM C1231.

The pad material 5 is disposed on the lower surface of the pressing portion 2 of the cap member 1 and has an inner diameter d ₀ of 102 mm, and 104 mm and 106 mm as comparative examples. These pad materials are made of chloroprene,
The hardness was 65 degrees or 75 degrees, and the hardness was 90 degrees as a comparative example. The pad material has a thickness of 10 mm and a diameter of 102 mm for each rubber hardness.
mm, and 104 mm and 106 mm as comparative examples.
Was used.

The rubber hardness tester for measuring the rubber hardness of the pad material is JLSK 16301 (vulcanized rubber physical test method).
A durometer JA type capable of measuring an accuracy of up to 1 degree as specified in the above was used.

A specimen was prepared as follows. The concrete slump target value is 18 cm, the air amount target value is 4.5%, and the concrete strength is 20, 30.
To obtain 45 N / fmm ² and 45 N / fmm ² , test kneading was performed to determine the composition of concrete in this measurement (see Table 1).

[0047]

[Table 1]

The mixer used for the measurement was a 100-liter pan-type forced kneading mixer, in which the kneading amount of one batch was 90 liters. In the mixing, the coarse aggregate, the fine aggregate (1/2), the cement, and the fine aggregate (1/2) are put into the mixer in this order, and after 30 seconds of the empty kneading, the admixture is contained for 30 seconds. Mixing water was added and the mixture was run for 90 seconds. The mixed concrete was transferred to a kneading boat, subjected to one round trip, and then subjected to each test.

According to ZKT203 (how to prepare a specimen for strength test of concrete using a lightweight mold), nine concrete specimens were produced for each measurement condition using a lightweight mold with a φ10 × 20 cm plastic crack. The test specimen was demolded and cured in water at 20 ± 3 ° C. until the age of 7 days 24 hours after casting.

The compressive strength test was carried out according to Jls A 1108 (test method for compressive strength of concrete). Prior to the compressive strength test, the bottom surface of the specimen was carefully finished with a grinder, and the upper surface was subjected to a simple ironing process.
After finishing in the range of 12 mm to 1.50 mm, the flatness of both end surfaces of the specimen was measured at 17 places by a flatness meter, and then subjected to a compressive strength test.

After confirming that there is no dust or the like on the inner surface of the cap member, the pad member 5 is mounted in the cap member 1,
The initial value of the rubber hardness was measured with a rubber hardness meter, and the test piece was covered with a cap member. After adjusting the cross section of the test piece so that the center of the cap member coincided, a compression strength test was performed (hereinafter, referred to as
The method for capping the specimen according to the present embodiment is referred to as unbond capping).

At the end of the compressive strength test, the pad material in the cap member was cleaned, and the hardness of the pad material was measured with a rubber hardness meter.

Both ends of the specimen were polished and Jls A110
The average value of the results of the compressive strength test performed according to No. 8 was used as the reference strength in this example. Table 2 shows the results of compressive strength tests performed on various types of concretes with various changes in the size of the cap member and the hardness of the pad material. Table 3 shows the results of measuring the compressive strength ratio by changing the hardness of the pad material with the dimensions of the test sample being 10 × 20 cm and the diameter of the pad material being 102 mm.

[0054]

[Table 2]

[0055]

[Table 3]

As shown in Table 2, the test values of the compressive strength were as follows:
The higher the hardness of the pad material, the smaller the value. When the size of the cap member is larger, the strength is greatly reduced. When a cap member having an inner diameter of 106 mm is used and a pad material having a hardness of 90 degrees is used, about 2 N / mm ^{2 with} respect to the reference strength. , A decrease in strength was observed.
This is presumably because when the clearance between the specimen and the inner surface of the cap member is large, the pad material is deformed along the bottom surface of the cap member with an increase in load, and the end surface of the specimen cannot be restrained. As a result, it is considered that the fracture of the concrete specimen caused cracking on the upper end side surface in contact with the pad material, which developed and accelerated the fracture. For the purpose of confirming these assumptions, the specimen at the time of destruction was observed. As a result, most of the upper side surfaces are peeled off when a cap member having an inner diameter of 106 mm is used, which supports the above measurement.

The condition of cracking of the pad material at the end of the test was as follows.
mm, and the rubber hardness decreased by 4 degrees, making it impossible to reuse the pad material. As a condition for utilizing unbond capping, that is, a condition for obtaining a test value in which the test value by unbond capping is the same as the compressive strength by polishing at both ends, if the strength ratio between the two is 0.98 or more (similar to that of ASTM Cl231). In this case, the range of the dimension of the cap member and the hardness of the pad material suitable for this is a region surrounded by a thick line in Table 2.

As shown in Table 3, the strength ratio of the pad material was 0.98 to 1.02 in the range of 65 ± 5 degrees.
It can be seen that it falls within the range.

Next, Table 4 shows the measurement results when the thickness of the pad material was changed.

[0060]

[Table 4]

In Table 4, W / C = 40-60% The thickness of the pad material is 6 m at an inner diameter of 102 mm of the cap member.
The intensity ratio in the case of m is 0.979 to 1.010. The strength ratio when the thickness of the pad material was 13 mm was 1.003 to 1.009. Thickness 10
The strength ratio in the case of mm is 1.002 to 1.014, which indicates that the same test result as the reference strength can be obtained. Similarly, when the pad material has a thickness of 6 mm when the inner diameter of the cap member is 104 mm, the strength ratio is 1.039 to 0.954. The strength ratio when the thickness of the pad material is 13 mm is 0.970 to
0.976.

The flatness of the upper surface of the test piece was adjusted to 0.12 mm to 1.50 mm by simple ironing at the time of forming the test piece.
(Measured at 17 points per specimen), but no clear effect on the strength due to the difference in flatness of the specimens was observed, regardless of the hardness of the pad material used.

The compression test using the same capping device as the above test was performed by measuring the inclination of the upper surface of the test piece (the height of the test piece being inclined and the height generated with reference to the bottom face of the test piece) of 3 m.
m and 6 mm. Further, the compression test using the same capping device as the test was performed on the specimen having a concave upper surface (when the upper central portion is lower than the upper side surface by 3 mm) and a convex type (when the upper central portion than the upper side surface of the specimen was 3 mm).
Low). Table 5 shows the results.

[0064]

[Table 5]

Further, an additional measurement was performed for the purpose of coping with a decrease in the strength of the test specimen having a concave upper surface.

That is, standard sand from Toyoura, land sand from Kisarazu (passing through a sieve of 0.15 mm) and stone powder were placed in the concave part on the upper surface of the specimen, the upper surface was smoothed smoothly with a paste knife, and unbonded capping was applied thereto. The results are shown in Table 6 in comparison with the compressive strengths of the test pieces subjected to polishing and capping.

[0067]

[Table 6]

Table 6 shows test values at 150 loading times, and shows that the strength ratio is 0.99 or more if the material used as the filler passes through a 0.15 mm sieve.

Next, the influence of the difference in the dimensions of the test pieces on the compressive strength was measured. Dimensions of the test specimens for compressive strength test were φ10 × 20 cm and φ12.5 × 25 cm, and 15 specimens were prepared for concrete with the target strength of 20 and 30 N / mm ² , respectively.
The applicability of unbond capping was verified. The test method by unbond capping was performed in the same manner as the above test. As the reference strength, a result obtained by polishing both ends of a simultaneously prepared specimen and performing a test according to JIS A 1108 was used. Table 7 shows the results of this test.

[0070]

[Table 7]

In Table 7, the test value of the compressive strength by unbond capping with respect to the reference strength is 0.3 to 0.6.
Although a decrease of N / mm ² was observed, the intensity ratio was 0.97.
０．９0.99, which satisfies the standard of ASTM intensity ratio of 0.98 except for one data. It is shown that the polishing capping and the unbonded capping have the same strength regardless of the difference in the specimen size.

Next, the usage limit of the pad material will be described. In this example, a small number of high-strength specimens were repeatedly loaded with a predetermined strength to observe the state of the pad material.

As for the shape of the upper surface of the specimen for the compression test, a specimen having no inclination of the upper surface of the specimen by ironing and finished in parallel with the bottom surface of the specimen (degree of inclination: 0 mm) is repeatedly loaded to form a pad material. The use limit was tested from hardness.

This test was performed twice in Test A and Test B, and the concrete specimen used for the measurement had a sufficiently higher strength than the target strength, and the concrete specimen had a predetermined strength (20, 130 and After a load corresponding to 45 N / mm ² ) was applied, unloading was repeated.

Each time the specimen was loaded, the specimen in the cap member was rotated by 36 degrees with respect to the central axis. At the start of the test and at every 50 loadings, the compressive strength was tested using a standard specimen made of gypsum, and the hardness of the pad material was measured with a rubber hardness tester.

The inner diameter of the capping device was 99.5 mm for test A and 100 mm for test B.
Pad material is outer diameter 100mm, thickness 10mm, rubber hardness 6
The measurement was carried out using 4-67. The test results are shown in Table 8 (Test A) and Table 9 (Test B).

[0077]

[Table 8]

[0078]

[Table 9]

The compression test using the same capping device as the test A described above was performed by measuring the inclination of the upper surface of the specimen (the inclination of the specimen and the height generated with reference to the bottom of the specimen) of 3 mm.
And 6 mm.

Further, a compression test using the same capping device as in the above-mentioned test A was performed on a concave type (when the upper central portion was lower by 3 mm than the upper side surface of the sample) and a convex type (when the upper side was higher than the upper side surface of the sample). (When the central part is lower by 3 mm). Tables 10 to 13 show the test results.

[0081]

[Table 10]

[0082]

[Table 11]

[0083]

[Table 12]

[0084]

[Table 13]

Based on the above measurement results, the usage limit of the pad material is determined. From these tables, it can be seen that the use limit of rubber cannot be uniformly determined from the relationship between the number of test repetitions and the strength ratio. However, when focusing on the relationship between the strength ratio and the hardness of the pad material and arranging the relationship for each shape of the upper surface of the specimen, although the relationship between the two slightly varies, as shown in FIGS. It turned out to be shown by a straight line. Therefore, a linear equation showing the relationship between the strength ratio and the rubber hardness was obtained by the least square method, and the amount of reduction in rubber hardness at which the strength ratio was reduced from 1 to 0.98 was obtained. The results are shown in Table 14.

[0086]

[Table 14]

In Table 14, the amount of decrease in rubber hardness for ensuring a strength ratio of 0.98 is 2.60 degrees on average, though it varies depending on the shape of the upper surface of the test piece. However, for safety, the strength ratio was even more vigorous than the ASTM standard of 0.98, and the value was set to 0.985. Table 15 shows an example of calculating an allowable value for the reference intensity.

[0088]

[Table 15]

In Table 15, the limit value of the intensity ratio was 0.98.
, The difference from the reference value is 0.3 to 0.9 N / m
A m ^2, and the difference by the intensity ratio and 0.985, reduced to 0.2~0,7N / mm ^2, test values of narrower range than the variation inherent in the concrete specimen is obtained Was. When the limit value is set to 0.98, the decrease in the hardness of the pad material is 2.0 degrees on average. Therefore,
The use limit of the pad material can be managed by a rubber hardness meter, and when the value of the hardness at the time of the first use decreases twice, it can be regarded as the use limit of the pad material.

Further, the rebound resilience and specific gravity of the pad material
The effect on the measured value of the compressive strength was measured.

In this measurement, the hardness and specific gravity of chloroprene and polyurethane pad materials were measured in a thermostat at a temperature of 20 ° C. in accordance with JIS K 6253, 6255, and 6350. This is the result of measuring the specific strength ten times.

Tables 16 and 17 show the results.

[0093]

[Table 16]

[0094]

[Table 17]

From Table 16, when chloroprene rubber was used as the pad material, the rebound resilience of the pad material was 53%.
% And specific gravity of 1.41, it can be seen that proper measurement can be performed.

When the range where the compressive strength ratio is appropriate is estimated based on the measurement result, the rebound resilience 53
± 3%.

When the range where the compressive strength ratio is appropriate is estimated based on the measurement result, the specific gravity is 1.40 ± 0.0
It becomes 3. Also, from Table 17, when polyurethane rubber was used as the pad material, the resilience of the pad material was 59%.
%, And the specific gravity is 1.30, it can be seen that proper measurement can be performed.

[0098] In order to verify the above results, the strength ratio of the specimen was measured for pad materials having different rebound resilience and specific gravity. Table 18 shows the pad material made of chloroprene rubber.
9 shows the result of an experiment performed using a pad material made of polyurethane.

[0099]

[Table 18]

[0100]

[Table 19]

According to both tables, the pad material made of chloroprene rubber has a rebound resilience of 53 ± 3% and a specific gravity of 1.40 ±.
The range of 0.03 is appropriate, and the resilience of the polyurethane pad material is 59 ± 3% and the specific gravity is 1.3.
It can be seen that the range of 0 ± 0.03 is appropriate.

Therefore, according to the present example, the capping device in the concrete compressive strength test device could satisfy the following conditions.

When the size of the cap member used for unbond capping is about 2 mm larger than the diameter of the specimen, a stable test value can be obtained, and the value is determined by polishing capping and the test result by Jls A 1108. Well matched. The pad material is not more than the inner diameter of the steel cap member, the thickness is 10 mm, and the rubber hardness is Jls.
If the measurement is performed with an A-type durometer specified in K6301 and about 60 ± 5 degrees, JlSA530 is used.
8 can be applied to the standard product. As the influence of the shape of the upper surface of the specimen, when the inclination of the upper surface is 0, 3 and 6 mm and when the upper surface is convex, the reference strength (polished at both ends and Jls A110
8 was 0.98 or more. When the upper surface of the specimen is concave, the test value is slightly smaller than in other cases, but the concave portion is filled with a granular substance passing through a 0.15 mm sieve in a sieving test of stone powder or fine aggregate. And then using a ruler to smooth the surface, then using unbonded capping, the same test as in the other cases can be performed. Specimen size is φ10 × 20cm and φ12.5 × 25
Since the strength test results in cm are equal, there is no effect of the difference in the specimen size on the test value in unbonded capping. For this reason, it is sufficient to use a rubber hardness meter to determine the usage limit of the pad material, not based on the number of times the pad material is used, and to use a new one when the amount of reduction in rubber hardness becomes two degrees. A very accurate test can be carried out if replaced. Further, in addition to controlling the hardness of the rubber, by measuring the rebound resilience and specific gravity of the rubber and setting the values of the rebound resilience and the specific gravity to appropriate values, a more accurate test can be performed.

[Second Embodiment] The present embodiment relates to a capping device in a concrete compressive strength test device for concrete of an early age.

In this example, concrete having the following composition was used. The cement used was ordinary Portland cement having a specific gravity of 3.16 and a fineness of 3270 cm ² / g. The fine aggregate is land sand from Hamaoka, Shizuoka Prefecture. The specific gravity of surface dry is 2.61, the water absorption is 1.41%, the coarse grain ratio is 2.89. The coarse aggregate is 1505 hard sandstone crushed stone from Iibuchi, Ibaraki Prefecture. The surface dry specific gravity was 2.63, the water absorption was 0.71%, and the coarse particle ratio was 6.14. Table 20 shows the composition of the concrete and the composition of the mixed concrete.

[0106]

[Table 20]

The kneading was performed by using a forced pan mixer having a capacity of 100 liters, continuously mixing and mixing four batches with a batch of 100 liters. Provided.

The specimen was molded using a lightweight plastic mold of φ10 × 20 cm according to JIS A1132. The specimens are 6 for each measurement condition described below.
This product was prepared, left in a room at 20 ± 3 ° C. until the test, and demolded at the age of the test.

In this embodiment, the same capping device as that used in the first embodiment is used. That is, the cap member 1 is the same as that used in Example 1, the inner diameter is 102 mm, and the inner diameter is 104 mm and 10 mm in comparison.
A 6 mm one was used. The rubber pad used had a constant thickness of 10 mm, an outer diameter equal to the inner diameter of the steel cap, and a hardness of 30 °, 40 ° and 50 °.

Then, the cap member 1 into which the pad material 5 was inserted was put on the upper surface of the finished test piece 4, and the compressive strength was measured. As shown in Table 21, the age of the test was determined based on the formwork for each structural member in the Concrete Standard Specification (hereinafter referred to as “Specification”) and the Building Construction Standard Specification JASS5 Reinforced Concrete Work (hereinafter referred to as “JASS5”). The time at which the reference value of the compressive strength was obtained at the time of demolding was obtained, and the time was estimated by preliminary measurement. The result is shown in FIG.

[0111]

[Table 21]

As shown in FIG. 11, the age at which each strength is obtained is 12 hours for 3.5 N / mm ² .
At 0 N / mm ² , it was 14 hours, and at 14.0 N / mm ² , it was 34 hours.

The level of the measurement was 27 conditions in which the inner diameter of the cap member and the hardness of the pad material were combined with respect to the above-mentioned three ages. In addition, for comparison, the water powder ratio was 17% 2 hours before the compression test according to JlSA1132.
Gypsum capping was performed using the high-strength gypsum BR described above, and the compressive strength was tested.
Table 22 shows the measurement results of the compressive strength.

[0114]

[Table 22]

In Table 22, the reference strength increases with the transition of the age, and is 4.24 N / m in the case of 12 hours.
For m ^2, if the 14-hour 6.01N / mm ² and 34 hours and has a 14.5N / mm ^2. Table 2
In the portion surrounded by the thick line frame of 2, an appropriate test value can be obtained if the ratio between the strength by the unbonded capping method in ASTC1231 and the reference strength (hereinafter referred to as the strength ratio) is within the range of 1 ± 0.02. Therefore, the test values included therein are shown.

That is, as the capping device, the inner diameter 10
The test value when using a 2 mm cap member and a pad material having a hardness of 50 ° is 4.28 N / mm ^{2 for} each material age, and 6.
A 00N / mm ² and 14.3N / mm ^2, respectively, the intensity ratio 1. 009,1.000 and 0.98
6, which is a test value similar to the reference strength.

On the other hand, when a cap member having an inner diameter of 102 mm and a pad material having a hardness of 30 ° and 40 ° were used, the strength ratio was 0.922 to 0.997, indicating a slight tendency to decrease. Was. When a steel cap having an inner diameter of 104 mm was used, the strength ratio was 0.993 to 1.128, regardless of the difference in rubber hardness, and almost all cases tended to increase. Further, when a cap member having an inner diameter of 106 mm was used, the strength ratio was 0.986 to 1.156, irrespective of the rubber hardness, and a correct measurement value was not obtained.

When the strength ratio is larger than the predetermined range in the above test results, the clearance between the specimen and the cap member is large, and the hardness of the pad material is smaller than the hardness at which an appropriate test value can be obtained. It is presumed that the pad material is deformed along the bottom surface of the cap member with an increase in the load, restrains the upper end portion of the test sample, and becomes longer than the reference strength in order to shorten the test sample. Conversely, when the strength ratio is small, the pad material adheres to the unevenness of the specimen placing surface with the increase in load, and the load concentrates on the convex part of the specimen placing surface before transmitting the load evenly. Therefore, it is considered that it is broken in the low strength region and becomes smaller than the reference strength.

From the above results, determination of the mold release time based on the compressive strength (compressive strength is 3.5 to 14.0 N / mm ² )
When the unbonded capping method is applied to the device, it is considered appropriate that the inner diameter of the cap member is 102 mm and the hardness of the pad material is 50 °.

A case will be described in which the present embodiment is applied to a compressive strength test for determining the timing of mold release from the bottom surface of a slap and a beam using the capping device of the specifications obtained by the above measurement. The cement used was a blast furnace type B cement having a specific gravity of 3.04. The fine aggregate is crushed lime sand, with a specific gravity of 2.68 and a water absorption of 0.70%.
F. M. 3.18, coarse aggregate is lime crushed stone 4005, surface dry specific gravity 2.70, water absorption 0.20%, F.C. M.
Using 7.26, W / C = 69.1%, s / a = 42.
Specimens were prepared by mixing concrete of 8%, 5 cm of slump and 4.5% of air ink at a ready-mixed concrete plant, and subjected to a compressive strength test.

FIG. 12 shows an example of the measurement result. In FIG. 12, the value obtained by the capping method shown in the conventional example and the value obtained by the measurement method (unbond capping method) using the capping device shown in this example are shown by straight lines. Each compression strength is 2.08-26.
A 5N / mm ² and 2.03~25.0N / mm ^2, the intensity ratio of the conventional method and the unbonded capping method For 18.8N / mm ² or less from 0.975 to 1.02
0, 18.8 N / mm ² or more, 0.931 to 1.0
08, which is approximately 20 N /
It can be seen that the capping device of this example can be applied to a strength test of about ² mm2 or less.

Further, in a ready-mixed concrete plant, in a normal process control, six specimens were prepared, three of which were subjected to a compressive strength test using a cement paste capping method, and the remaining three were subjected to a compressive strength test. The practicality of the process control test in a factory was examined. One example of the test results is shown in FIG. In FIG. 13, the compressive strength by the unbond capping method is 24.8-35.2 N / m.
m ² (average: 29.9 N / mm ² , standard deviation δ;
69 N / mm ² ), and the compressive strength according to the conventional method is 2
5.0-35.2 N / mm ² (average value: 30.2 N / m
m ² , standard deviation δ; 2.51 N / mm ² ), and similar results were obtained for both test values except for exceptional values.

The ratio of the strength of the unbonded capping method to the compressive strength of the conventional method was 0.1% except for some samples.
From 980 to 1.010, it can be seen that the capping apparatus according to this example can be applied to the process control test.

Therefore, according to the capping apparatus of this embodiment, the compression strength test of the low-strength concrete used for the determination of the mold release time, the determination of the mold release time even in the ready-mixed concrete factory, and the process control test Can be performed as appropriate as in the conventional tests for gypsum capping.

[Third Embodiment] The present embodiment relates to a capping device in a mortar compressive strength test device.

The cement used for the measurement was ordinary Portland cement, having a specific gravity of 3.16 and a fineness of 3260 cm.
It is those of ^2/8. The fine aggregate is river sand from Fujian Province of the People's Republic of China, with a specific gravity of 2.59 and a water absorption of 1.05.
%, F.I. M. The one of 3.08 was used.

The mixing ratio of mortar was W / C = 40, 50 and 60%.
It was adjusted to be 90 ± 10 mm. The composition of the mortar used for the measurement is as shown in Table 23. The kneading was carried out in accordance with the method B of Annex 9 of JIS A 5308.

[0128]

[Table 23]

The test specimen was molded according to the method B of Annex 9 of Jls A 5308. The mold is Jls A
This was performed using a lightweight formwork with an inner diameter of 5 cm similar to that shown in Annex 12 of 5308. After casting, the test specimen was allowed to stand in a constant temperature room at 20 ° C., and the mortar test specimen was kept moist with a compress and a vinyl sheet. The specimen was released from the mold 24 hours after molding, and the specimen was removed from the mold at 40 hours indicated in Jls A 1805.
Curing was carried out with warm water at a temperature of 7 ° C until the age of 7 days, and subjected to a compressive strength test.

In the compressive strength test, the compressive strength was tested by placing a capping device in which the pad member 5 was inserted into the cap member 1 on the finished upper surface of the test piece. In the measurement regarding the selection of the inner diameter of the cap member and the rubber hardness, the inner diameter of the cap member was changed to 51, 52, and 53 mm, and the rubber hardness of the pad material was changed to 55, 65, and 75 °. In the measurement for selecting the thickness of the pad material, the rubber hardness was fixed at 65 °, and the thickness was changed to 6, 10 and 13 mm.
For comparison, the upper surface of the test piece was polished and finished just before the compression test according to JIS A1108, and the compressive strength was tested, which was taken as the reference strength (reference strength) in this measurement. Table 24 shows the measurement results when the inner diameter and the rubber hardness of the cap member 1 were changed.

[0131]

[Table 24]

In Table 24, the inner diameter 51 of the cap member is shown.
mm when the rubber hardness is 55 ° to 75 °.
52.0-53.6 N / m at W / C = 40% at °
m ² , 37.5-39.7 N / mm ² at 50%, 60%
And 29.5-30.4 N / mm ² . These test values were used as the reference strength at 55.8 for each W / C.
Compared with 43.6 and 33.2 N / mm ² , this was expressed as an intensity ratio. According to ASTM C1231, this value is 1
If it is within ± 0.02, it is evaluated that the test has been correctly performed, and the respective values are 0.932 to 0.961,
0.893-0.912 and 0.890-0.917
It has become.

When the inner diameter is 53 mm, the strength ratio is 0.912 to 0.982, 0.909 to 1.046.
And 0.896 to 1.05, indicating that most conditions tended to be smaller than the reference strength. On the other hand, the test result when the inner diameter of the cap member was 52 mm and the pad material having the hardness of 65 ° was good, and the strength ratio was W
1.002 for / C = 40%, 0.98 for 50%
In the case of 5, 60%, it was 1.014, and the same test result as the reference strength was obtained. Therefore, φ10x20cm
As with concrete specimens, the inner diameter of the cap member should be 2 mm larger than the specimen diameter, and if the pad material had a hardness of 65 °, a mortar specimen of φ5 × 10 cm could be subjected to a normal compressive strength test. It was shown to be applicable. Next, Table 25 shows the measurement results when the thickness of the pad material was changed.

[0134]

[Table 25]

In Table 25, the strength ratio when the pad material thickness is 6 mm at W / C = 40 to 60% is 0.96.
9 to 1.010. In addition, the thickness of the pad material 1
The intensity ratio in the case of 3 mm was 0.967 to 1.009. On the other hand, the strength ratio when the thickness is 10 mm is 0.98.
5 to 1.014, indicating that the same test result as the reference strength can be obtained.

From the above results, the capping member used in the compressive strength test of the φ5 × 10 cm mortar specimen by the unbond capping method has a strength applicable range of 33 to
56N / mm ² field stand, inner diameter of cap member is 52m
m, pad material hardness is 65 °, pad material thickness is 1
It can be seen that 0 mm is appropriate.

Using the capping member obtained in the above measurement, the above measurement results were verified and the range of applicable compressive strength was examined. Fine aggregate used in the measurement, the People's Republic of China Fujian producing river sand (referred to as China sand) and Ganshoji sand at a compression strength to prepare a specimen of 33~70N / mm ^2, optionally after hot curing Compressive strength test was conducted at the material age. Table 26 shows the measurement results.

[0138]

[Table 26]

In Table 26, the inner diameter of the cap member was 5
2mm, pad material hardness 65 °, using Chinese sand
Strength by unbond capping is 33.1N /
mm ^TwoAnd the reference strength is 32.7 N / mm^Twoso
there were. The intensity ratio in this case is 1.014, which is the same as the reference strength.
Various results were obtained, demonstrating the above results. to this
In comparison, unbonded capping using Iwaijira sand
71.5 N / mm^TwoAnd the reference strength is 6
9.2 N / mm^TwoIt has become. The intensity ratio in this case is
1.033, the appropriate test value could not be obtained
Performance is shown.

Regarding the specifications of the high-strength mortar equipment, the load corresponding to the clearance between the test piece and the cap member and the rubber hardness is large when the strength is high, so that the circumferential direction of the top surface of the test piece is large. It was speculated that a correct test could be performed by suppressing the deformation of. Therefore, in order to suppress the amount of deformation of the rubber, the inner diameter of the cap member is 51 mm, which is 1 mm smaller than the above, and the rubber hardness is 10 ° larger, 75 °, than the above.
The test of the high strength mortar was performed by using as a trial. The measurement results are as shown in Table 20. The strength by the unbonded capping method was 70.5 N / mm.
² , the reference strength is 69.2 N / mm ² .

The intensity ratio in this case is 1.019,
It is shown that the experimentally determined cap member and pad material can be correctly tested by the unbonded capping method. From these results, it can be seen that the specifications of the equipment used for the unbonded capping method in a region having a compressive strength of about 70 N / mm ² or less can be applied if the inner diameter of the cap member is 51 mm and the rubber hardness is 75 °.

Using a pad member having an inner diameter of a cap member of 51 mm and a rubber hardness of 75 °, applicability as a device for high-strength mortar was verified by measurement. The fine aggregates used for the measurement were Fujikawa sand, Ogasayama sand, Iwaijira sand, Tenryugawa sand and crushed sand from Otowa, W / C = 50%, S / C =
Thirty mortar specimens of 3.0 were prepared for each type of fine aggregate, and a compressive strength test was conducted at an arbitrary age after warm water curing.

For comparison, the compressive strength was tested by capping the upper surface of the test piece with cement paste, and this was used as the reference strength. Table 27 shows the measurement results.

[0144]

[Table 27]

In Table 27, although some variation is observed in some data, the strength of the mortar using various fine aggregates by the unbonded capping method is 50.9 to 7
0.0N / mm ² , reference strength 51.1-71.4N
/ Mm ² . The intensity ratio in this case is 0.980
−1.002, a test value similar to that of the reference specimen was obtained, the measurement result was reproduced, and when testing a high-strength mortar, the inner diameter of the cap member was 51 mm and the rubber hardness was 7
It turns out that the thing of 5 degrees is applicable.

According to this example, the capping device in the mortar compressive strength test device could satisfy the following conditions. When the compressive strength is 33 to 56 N / mm ^2, an appropriate compressive strength test can be performed by using a cap member having an inner diameter of 52 mm, a pad material having a hardness of 65 ° and a thickness of 10 mm. When the compressive strength is 51-71 N / mm ^2, an appropriate compressive strength test can be performed by using a cap member having an inner diameter of 51 mm, a pad material having a hardness of 75 ° and a thickness of 10 mm.

[0147]

As described above, since the present invention has the above-described configuration and operation, a high-precision compressive strength test capable of obtaining a measurement result equivalent to that of the conventional JIS standard can be simply and simply performed. There is an effect that it can be performed in a short time and at low cost.

That is, according to the present invention, the deterioration of the pad material can be objectively evaluated based on the decrease in rubber hardness measured by a rubber hardness meter, and the proper pad material can be used at all times. And the reliability of the measured value of the compressive strength of the mortar can be increased. Further, according to the present invention, by selecting an appropriate material as the pad material, it is possible to obtain a value equivalent to a value obtained by performing a compressive strength test on a test piece prepared in accordance with JlsA 1132.

Further, according to the present invention, the thickness of the pad material 5, the initial value of the rubber hardness and the allowable range of reduction, the rebound resilience, and the specific gravity were determined by conducting many experiments on concrete specimens. Based on the results, Jls A 1132
It is determined that a value equivalent to the value (reference value) of a specimen prepared according to the standard can be obtained. Therefore, according to the present invention, for a concrete specimen,
The measurement result equivalent to the JIS standard can be easily obtained in a short time and at low cost without any trouble such as capping with a mortar.

Further, according to the present invention, since the thickness of the pad material 5 and the initial rubber hardness and the value of the allowable range for reduction are set to appropriate values, the concrete material of the young material (the mold removal time) can be used. The measurement result of mortar equivalent to the JIS standard can be easily obtained in a short time and at low cost.

According to the present invention, even when the specimen has a concave portion on the upper end surface, the concave portion on the upper end surface of the specimen has 0.15
By placing a fine powder of not more than mm and flattening the surface, the measured value of the compressive strength can be properly performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a capping device in a concrete or mortar compressive strength test device according to the present invention together with a test piece.

FIG. 2 is a diagram showing a capping device in a concrete or mortar compressive strength test device according to the present invention, wherein (1) is a bottom view and (2) is a cross-sectional view taken along line ii-ii in (1).

FIG. 3 is a sectional view showing an example of a capping device in a conventional concrete compressive strength test device.

FIG. 4 is a graph showing a relationship between rubber hardness and strength at a slope of 0 mm on the upper surface of a specimen in Test A in the first example.

FIG. 5 is a graph showing the relationship between rubber hardness and strength when the upper surface of a test specimen in test B in the first embodiment has a slope of 0 mm.

FIG. 6 shows that the upper surface of the specimen in the first embodiment has a slope of 3 m.
3 is a graph showing the relationship between rubber hardness and strength at m.

FIG. 7 shows that the upper surface of the specimen in the first embodiment has a slope of 3 m.
3 is a graph showing the relationship between rubber hardness and strength at m.

FIG. 8 shows that the upper surface of the specimen in the first embodiment has a slope of 6 m.
3 is a graph showing the relationship between rubber hardness and strength at m.

FIG. 9 is a graph showing the relationship between rubber hardness and strength when the upper surface of the test sample in the first embodiment is in a concave state.

FIG. 10 is a graph showing the relationship between rubber hardness and strength when the upper surface of the test sample in the first embodiment is in a concave state.

FIG. 11 is a graph showing the relationship between material age and compressive strength in a preliminary test of the second embodiment.

FIG. 12 is a graph showing the relationship between the strength of the test piece according to the second embodiment and the strength by the conventional method and the unbonded capping method.

FIG. 13 is a graph showing an example in which the second embodiment is used for process control in a ready-mixed concrete factory.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cap member 2 Pressing part 3 Annular part 4 Specimen 5 Pad material

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Koji Ito 2-6-1-1, Hamacho, Funabashi-shi, Chiba Pref. Japan Federation of Ready-mixed Concrete Industries Inside Central Technology Research Institute (72) Inventor Toshihide Haga Horikiri, Katsushika-ku, Tokyo 1-chome No. 29-3 Haga Rubber Works (56) References Cement and Concrete Transactions, 51 (Dec. 25, 1997) Cement Association, Suzuki, Ito, Nakane, p. 578-581 (58) Field surveyed (Int. Cl. ⁶ , DB name) G01N 3/00-3/62

Claims (15)

(57) [Claims] 1. A flat pressing portion (2) and an annular portion formed on the lower surface of the pressing portion (2) and suspended in an annular shape with an inner diameter slightly larger than the outer diameter of the test piece (4). 3) a rubber cap member (5) disposed between the upper surface of the specimen (4) and the pressing portion (2) of the cap member (1). In the capping device in the concrete or mortar compressive strength test device, the pad material (5) has a constant thickness and a diameter equal to the inner diameter of the annular portion (3) of the cap member (1). A chloroprene rubber or polyurethane rubber plate material formed, wherein the rubber hardness of the pad material (5) at the time of initial use is a predetermined hardness, and the rubber hardness measured by a rubber hardness meter at the time of use is the value at the time of initial use. Decrease within a specified amount from rubber hardness There, resilience during use of the pad material (5) is chloroprene rubber
And the specific gravity when the pad material (5) is used is chloroprenego.
A capping device in a concrete or mortar compressive strength test device, which has been confirmed to be within a predetermined range for each of rubber and polyurethane rubber . 2. The pad material (5) has a thickness of 10 mm.
The rubber hardness at the time of initial use is 60 ± 5 degrees (JIS
2. The capping device in a concrete or mortar compressive strength test device according to claim 1, wherein the amount of decrease in rubber hardness as measured by a rubber hardness meter during use is within 2 degrees. 3. The pad material (5) has a thickness of 10 mm.
The rubber hardness at the time of initial use is 50 ± 5 degrees (JIS
2. The capping device in a concrete and mortar compressive strength test device according to claim 1, wherein the rubber hardness measured by a rubber hardness meter during use is within 2 degrees. 4. The pad material (5) has a thickness of 10 mm.
The rubber hardness at the time of initial use is 65 ± 5 degrees (JIS
2. The capping device in a concrete or mortar compressive strength test device according to claim 1, wherein the amount of decrease in rubber hardness as measured by a rubber hardness meter during use is within 2 degrees. 5. The pad material (5) has a thickness of 10 mm.
The rubber hardness at the time of initial use is 70 ± 5 degrees (JIS
2. The capping device in a concrete or mortar compressive strength test device according to claim 1, wherein the amount of decrease in rubber hardness as measured by a rubber hardness meter during use is within 2 degrees. 6. The pad material (5) is made of chloroprene rubber, has a rebound resilience in use of 53 ± 3% and a specific gravity of 1.40 ± 0.03. ,
A capping device in the concrete or mortar compressive strength test device according to claim 4 or 5. 7. The pad material (5) is made of polyurethane rubber, has a rebound resilience in use of 59 ± 3% and a specific gravity of 1.30 ± 0.03. ,
A capping device in the concrete or mortar compressive strength test device according to claim 4 or 5. 8. A flat pressing portion (2) and an annular portion formed on the lower surface of the pressing portion (2) and having an inner diameter slightly larger than the outer diameter of the specimen (4) and suspended in an annular shape. 3) a rubber cap member (5) disposed between the upper surface of the specimen (4) and the pressing portion (2) of the cap member (1). In a concrete or mortar compressive strength test method of applying a compressive load to a specimen using a capping device (10) consisting of: and measuring the compressive strength of the specimen, the pad material (5) has a thickness of A plate member of chloroprene rubber or polyurethane rubber having a constant diameter and the same diameter as the inner diameter of the annular portion (3) of the cap member (1) and having a predetermined predetermined rubber hardness at the time of initial use is used. The rubber hardness measured by a rubber hardness meter during use Initially, it was confirmed that the rubber hardness during use was within the specified range, and the rebound resilience measured during use was chloroprene rubber or rubber.
Is within a predetermined range for each of the polyurethane rubbers , and the specific gravity measured at the time of use is chloroprene rubber or polycarbonate.
A test method for compressive strength of concrete or mortar to be loaded on a specimen after confirming that it is within a predetermined amount range for each urethane rubber . 9. The pad material (5) has a thickness of 10 mm.
The rubber hardness at the time of initial use is 60 ± 5 degrees (JIS
The concrete or mortar compression according to claim 8, wherein the rubber hardness is measured using a rubber hardness meter at the time of use, and that the measured decrease in rubber hardness is within 2 degrees. Strength test method. 10. The pad material (5) has a thickness of 10 m.
m and the rubber hardness at the time of initial use is 50 ± 5 degrees (JIS
9. The concrete or mortar compressive strength test method according to claim 8, wherein the method of the present invention is a method for testing the concrete or mortar compressive strength using a material which is K6301) and confirming that a decrease in rubber hardness measured during use is within 2 degrees. 11. The pad material (5) has a thickness of 10 m.
m and the rubber hardness at the time of initial use is 65 ± 5 degrees (JIS
9. The concrete or mortar compressive strength test method according to claim 8, wherein the method of the present invention is a method for testing the concrete or mortar compressive strength using a material which is K6301) and confirming that a decrease in rubber hardness measured during use is within 2 degrees. 12. The pad material (5) has a thickness of 10 m.
m and the rubber hardness at the time of initial use is 70 ± 5 degrees (JIS
The concrete or mortar compressive strength test method according to claim 8, wherein K 6301) and a decrease in rubber hardness measured during use is within 2 degrees. 13. The pad material (5) is made of chloroprene rubber, has a rebound resilience in use of 53 ± 3%, and a specific gravity of 1.30.
The concrete or mortar compressive strength test method according to claim 9, claim 10, claim 11 or claim 12, wherein the concrete or mortar has a strength of 40 ± 0.03. 14. The pad material (5) is made of polyurethane rubber, has a rebound resilience in use of 59 ± 3% and a specific gravity of 1.
13. The concrete or mortar compressive strength test method according to claim 9, wherein the concrete or mortar has a strength of 30 ± 0.03. 15. The cap member (1) is attached to the specimen by filling a recess formed on the upper surface of the specimen with a particulate material having a particle size of 0.15 mm or less. The concrete or mortar compressive strength test method according to claim 12, claim 13, or claim 14.