φ75mm 供試体を用いたコンクリートの圧縮強度に関する研究

18

75mm

Article

75mm

*1 *2 *3 *4 *4 *5 *5 *1 *2 *3 *4 *5

A Study on Compressive Strength of Concrete with

75mm Specimen

Taiga SAKAMOTO

*1

_{, Takehiro SAWAMOTO}

*2

_{, Hiroshi JITOSONO}

*3

_,

Norikiyo NAKAMURA

*4

_{, Kazuyoshi WAKABAYASHI}

*4

_{, Shigeyuki SOGO}

*5

_{and Nobufumi TAKEDA}

*5 *1

_{Graduate School of Technologists, Institute of Technologists}

*2

_{Dept. of Building Technologists, Institute of Technologists}

*3

_{DIAREFORM Co., Ltd.}

*4

_{Japan Testing Center for Construction Materials (JTCCM), Central Test Laboratory}

*5

_{Near Future Concrete Association}

Abstract In this study, for the purpose of rationalization and labor saving of compressive strength test of concrete, we suggest 75 mm specimen. So, it was examined whether cylindrical specimen of 75 mm can be used as a specimen for concrete compressive strength test, and compared with 100 mm specimen. As a result, the compressive strength of 75 mm specimen was about the same strength as the 100 mm specimen, when the sealed curing and the underwater curing were carried out. The coefficient of variation of 75 mm specimen was about 5%. Therefore, it is considered that 75 mm specimen can be used as management specimen for standard underwater curing and on-site sealed curing specimen.

Key Words : Concrete, Specimen size, Compressive strength, Coefficient of variation, Curing

19

The Bulletin of Institute of Technologists, No. 9

2)

_150mm

100mm

3)

JIS A 1132

3

75mm

100mm

1

N

B

BB

2

N

BB

20mm

12cm

2

4

1

100 200mm

75

150mm

100mm

JIS A 5308

E

4)

75mm

100mm

75mm

2

100mm

JIS

A 1132

75mm

JIS

16mm

10cm

2

1

2

1

100mm

8

75mm

5

75mm

3

24 48

7

28

91

20

60

20

4

Table 1 Mix proportions of concrete

20

75mm

JIS A 1108

5)

_75mm

100mm

N

28

BB

91

9

3

100mm

75mm

3

9

3

9

100mm

75mm

5

45

100mm

75mm

N

BB

100mm

75mm

BB

BB

91

100mm

75mm

6

Fig. 3 Test for 75 mm specimen

(1) Placement (2) Compaction (3) Demolding (4) Compressive strength test

21

The Bulletin of Institute of Technologists, No. 9

100mm

100mm

75mm

N

BB

100mm

75mm

7

75mm

7

100mm

75mm

N

BB

100mm

75mm

2

N

28

BB

91

9

N

28

BB

91

8

100mm

3

75mm

5

8

75mm

100mm

75mm

100mm

75mm

3

N

28

BB

91

9

0 10 20 30 40 50 0 10 20 30 40 50 Compressive strength of specimen (N/ ) N-1 N-2 0 10 20 30 40 50 0 10 20 30 40 50 Compressive strength of specimen (N/ ) N-1 N-2 (1) Case of N 0 10 20 30 40 50 0 10 20 30 40 50 Compressive strength of specimen (N/ ) BB-1 BB-2 (2) Case of BB Fig. 5 Atmospheric curing

0 10 20 30 40 50 0 10 20 30 40 50 Compressive strength of specimen (N/ ) BB-1 BB-2 0 10 20 30 40 50 0 10 20 30 40 50 Compressive strength of specimen (N/ ) N-1 N-2 (1) Case of N (2) Case of BB Fig. 6 Sealed curing

22

75mm

75mm

BB-1

75mm

Table 2 Coefficient of variation of compressive strength

0 1 2 3 4 5 6 7 8 9

Atmospheric Sealed Underwater

N-1 N-2 BB-1 BB-2 0 1 2 3 4 5 6 7 8 9

Atmospheric Sealed Underwater

N-1 N-2 BB-1 BB-2

Fig 8 Coefficient of variation of compressive strength at state of 9 specimens (1) Case of 100mm specimen (2) Case of 75mm specimen

23

The Bulletin of Institute of Technologists, No. 9

B

2

75mm

100mm

(1) (4)

75mm

100mm

100mm

75mm

100mm

75mm

5

100mm

75mm

100mm

6

75mm

1) JIS A 1132 2014 2) pp.367-368 2009 3) p.230 1996 4) JIS A 5308 E 2014 5) JIS A 1108 2018 2.10 2.15 2.20 2.25 2.30 2.35

Atmospheric Sealed Underwater

N-1 N-2 BB-1 BB-2 2.10 2.15 2.20 2.25 2.30 2.35

Atmospheric Sealed Underwater

N-1 N-2 BB-1 BB-2

Fig 9 Apparent density of specimen at state of 9 specimens