11
The Bulletin of Institute of Technologists, No. 7
Article
*1 *2 *3 *4 *5 *1 *2 *3 *4 *5Effects of Demolding Timing and Wet Curing Timing on Surface Properties of Concrete
Kota KADOI
*1, Takehiro SAWAMOTO
*2, Koichiro SHITAMA
*3,
Masanori HIGUCHI
*4and Akiyoshi DAI
*5*1
Graduate Student, Graduate school of Technologists, Institute of Technologists
*2Dept. of Building Technologists, Institute of Technologists
*3
MAEBASHI Institute of Technology
*4SUMITOMO MITSUI Construction Co.,Ltd
*5
REVEX Consultant Co.,Ltd.
Abstract The property of concrete surface which influences the durability of concrete structure will be greatly affected on curing condition. In this study, the effects of demolding timing and wet curing timing on air permeability and strength of concrete with normal portland cement and poretland-blast furnace slag cement typeB were investigated. As a result, coefficient of air permeability, rebound number and compressive strength were measured, and in case of everything, portland-blast furnace slag cement typeB underwent influence of the demolding timing big compared with normal portland cement. The coefficient of air permeability and the rebound number didn t undergo influence of wet curing timing so mach. However, the compressive strength was so small that time to start wet curing became late.
Key Words : Concrete, Demolding Timing, Wet Curing, Coefficient of air permeability, Strength
5
7
1(N)
12
3.16g/cm
3B
3.04g/cm
32.61 g/cm
32.75
20mm
2.64g/cm
359.0%
AE
1
N
B
BB
27
1
400mm
600mm
1800mm
1800mm
600mm
3
JIS A
1132
1
2
5
7
14
28
2
1
1
3
6
1
7
28
2
1
1
3
Fig.1 Preparation of wall specimen
Fig.2 Wet curing of wall specimen and cylinder specimen (2) Cylinder specimen (1) Wall specimen
Table1 Mix proportions of concrete
11
The Bulletin of Institute of Technologists, No. 7
3
9
12
SIA262/1
2,3)3
5.5%
4)3
28
1
1
SIA262/1
6
600 600mm
3
3
NR
JIS A 1155
9
3
JIS A 1108
100mm
50mm
3
3
4
N
4.1% 5.1%
,BB
3.0% 4.3%
5.5%
N
BB
BB
N
51
N BB
-16m
2Fig.4 Relation between demolding timing and coefficient of air permeability
Fig.5 Relation between demolding timing and rebound number 0.1 1.0 10.0 100.0 0 10 20 30
Demoldig timing days
N Atmospheric curig N Wet curig BB Atomsphric curig BB Wet curig 1 2 5 7 14 28 30 32 34 36 38 40 42 0 5 10 15 20 25 30
Demolding timing day
N Atmospheric curig N Wet curing BB Atmospheric cring BB Wet cring
12
5
N BB
7
6
N
BB
1
N
4.1% BB
4.7%
BB
5
N
3.7% BB
2.9%
BB
N
BB
1
N
12N/mm
2BB
18N/mm
2N
BB
0.8
1.0%
7
BB
N
8
N
4.0% 4.3%
BB
3.5%
4.0%
5.5%
1
28
-16m
2 0.1 1.0 10.0 100.0 10 20 30 40 Compressive strength N/mm2 N Atmospheric curing N Wet cring BB Atmosphric cring BB Wet cring BB NFig.7 Relation between compressive strength and coefficient of air permeability
Fig.6 Relation between demolding timing and compressive strength 15 20 25 30 35 40 0 5 10 15 20 25 30
Demolding timing days
N Atmosphric cring N Wet cring BB Atmosphric cring BB Wet cring
11
The Bulletin of Institute of Technologists, No. 7
9
10
N
BB
N
7
BB
1
N
BB
(N)
B
(BB)
(1)
(2)
(1)
N
BB
BB
N
BB
(2)
Fig.8 Relation between wet curing timing and coefficient of air permeability
Fig.9 Relation between wet curing timing and rebound number
Fig.10 Relation between wet curing timing and compressive strength 0.1 1.0 10.0 100.0 0.1 1 10 100 1000
Wet curing starting after demolding at age of 1 day N Wet curing BB Wet curing Immediately 1(h) 3(h) 6(h) 1(d) 7(d) 28(d) 30 32 34 36 38 40 42 0.1 1 10 100 1000
Wet curing starting after demolding at age of 1 day N Wet curing BB Wet curing Immediately 1(h) 3(h) 6(h) 1(d) 7(d) 28(d) 15 20 25 30 35 40 0.1 1 10 100 1000
Wet curing starting after demolding at age of 1 day N Wet curing BB Wet curing
12
N
BB
RC
1) [ ] pp.122-123
2012
