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An Experimental Study on the Development of Setting Time
Control of Corrosion Inhibitor for Durability Improvement
Byungchul Moon 1a, Johyeong Yoo
2b, Hanseung Lee
3c, Jewoon Kyung
4d, Sung-Woo Shin
5, e
1Department of Architectural Environmental Engineering, Hanyang University, Ansan, 25-791, Korea 2Department of Architectural Environmental Engineering, Hanyang University, Ansan,425-791, Korea 3Department of Architectural Evironmental Engineering, Hanyang University, Ansan, 425-791, Korea 4Department of Architectural Environmental Engineering, Hanyang University, Seoul, 133-791, Korea 5 Director,
SUSB Research Center, Hanyang Univ., 1271 Sa-1 dong Sangnok-gu, Ansan, Kyunggi-do,
426-791, Korea
ABSTRACT
It is understood that there are various methods to protect the corrosion of reinforcing steels in concrete,
such as the nitrous acid lithium, calcium nitrate and etc. When we use the corrosion inhibitor in large
quantities there is some problem that accelerates setting time and affect to durability of concrete.
Lithium nitrate has a good effect on delays setting time, but it is more expensive calcium nitrate. So
calcium nitrate has used more than lithium nitrate. When calcium nitrate is used in large quantity,
there is a problem which accelerates setting time. The purpose of this study is developing a new
corrosion inhibitor, which improve durability of concrete.
KEYWORDS: corrosion inhibitor, calcium nitrate, setting time
1. INTRODUCTION
There is rust preventive mixing one of reinforcing rod corrosion control method in concrete in
such salt damage environment low class. The nitrous acid calcium that performance of kind of
corrosion inhibitor is proved lithium nitrate (LiNO2) developed newly as corrosion inhibitor for
Ca(NO2)2 and repair be. Use of the nitrous acid rust preventive is one of countermeasure to prevent
various reinforcing rod corrosion that occur in the reinforced concrete structure. There is lithium and
calcium in representative the nitrous acid corrosion inhibitor. Two kinds of corrosion inhibitor are
good to prevent concrete corrosion. However, time of coagulation quickens rapidly in case contain
calcium nitrate corrosion inhibitor more than 3%. With the reason calcium nitrate is acting role of
accelerator in the concrete coagulation speed. The other side, in the case of lithium nitrate, the mixing
amount does not influence in the setting time increase but because price is high, use of calcium nitrate
is more. The concrete coagulation speed developed new calcium nitrate corrosion inhibitor because
influence concrete constructability and durability.
Therefore, do by purpose that mix retardant of concrete agent in this research and develop new
corrosion inhibitor because delaying the setting time.
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2. Experiment plan and method
2.1 Experiment plan
Experiment plan is table 1. An experiment W/C 25%, 30% 2 levels, content of calcium nitrate by
1%, 3%, 5%, 7% 4 levels, and content of lithium nitrate to 1%, 3%, 5%, 7% 4 levels, used retardant
Sodium Gluconate calcium nitrate 3%, 5%, 7% 3%, 5%, 7%, and used high efficiency AE water
reducing agent to set flow 12±1㎝.
Table 1. Cement paste coagulation test mixing table
high efficiency AE water reducing agent Number W/C C Ca(No2)2 LiNo2
Sodium
Gluconate W/C25% W/C30%
1 - - - 5g 1.5g
2 1% - - 2g 1.5g
3 3% - - 2g 1.5g
4 5% - - 2g 1.5g
5 7% - - 2g 1.5g
6 3% - 0.12% 5g 1.5g
7 5% - 0.12% 5g 1.5g
8 7% - 0.12% 5g 1.5g
9 - 1% - 5g 1.5g
10 - 3% - 2g 1.5g
11 - 5% - - 1.5g
12 - 7% - - 1.5g
13 3% - 0.1% 2g -
14 5% - 0.15% 2g -
15
25%,
30% 1000g
7% - 0.18% 5g -
2.2 Experiments method
2.2.1 Test piece manufacture
Test piece put variable such as table 1 course to examine closely setting time of cement paste by
calcium nitrate and the agent mixing rate and with figure 2 test piece according to cement paste and
machine mixing method of mortar at hydroponics by KS L 5109, manufacture.
Figure 2. Mechanical mixing method and Flow Test
2.2.2 Experiment method
Setting time test of cement paste test piece is each variable setting time measurement and testing
method for setting time of hydraulic cement by vicat needle by KS L 5108 and carried out.
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Figure 3. Moisture machine & vicat needle
3. Experiment result and analysis
3.1 The corrosion inhibitor mixing rate and cement paste coagulation
Figure 4, 5 is experiment result about W/C 30%. It is corrosion inhibitor of same nitrite acid order,
but effect of lithium happens at time such as coagulation of normal cement paste, but the mixing
amount of the coagulation speed of cement paste that mix calcium increases, the coagulation speed
happened fast, and the coagulation speed appeared as effect of delay according to calcium nitrous
content is different as result that mix retardant Sodium Gluconate 0.12% to calcium nitrous 3%, 5%,
7%.
Figure 4. Start time of Cement paste Figure 5. End time of Cement paste
3.2 Setting time by Sodium Gluconate content
Figure 6, 7 to calcium nitrous 3%, 5%, 7% retardant Sodium Gluconate as result that mix each 0.1%,
0.15%, 0.18%. Can know that become late more than setting time of cement paste more than when the
coagulation speed of calcium nitrous mixed Sodium Gluconate of the uniformity amount to picture.
Figure 6. Start time by Sodium Gluconate content Figure 7. End time by Sodium Gluconate content
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3.3 Setting time by W/C
Figure 8, 9 is graph of setting time about W/C 25% and 30%. Is displaying that when it is 25% than W/C is 30%, setting time becomes longer.
Figure 8. Start time by W/C Figure 9. End time by W/C
4. CONCLUSION
The purposes of this study as following if summarize the result measured setting time of cement
paste about the nitrous acid calcium large quantity mixing.
In case mixed more than the nitrous acid calcium 3%, setting time of cement paste decreased
rapidly and case of lithium was expose that there is no change that is big. Also, was delayed in case of
is 3% in case of mixed Sodium Gluconate by the uniformity amount, but case that than setting time of
normal cement paste when was more than 5%, delay becomes less appeared.
ACKNOWLEDGEMENT
This work was supported by Sustainable Building Research Center Hanyang University which was
supported the SRC/ERC program of MOST (#R11-2005-056-04003-0) and the Center for Concrete
Corea (05-CCT-D11), supported by Korea Institute of Construction and Transportation Technology
Evaluation and Planning (KICTTEP) under the Ministry of Construction and Transportation (MOCT)
REFERENCES
Wonjun Park “Influence of the type of Nitrite Inhibitors and Mixing Ration Congealment of Cement
Paste”, 2006.
B. Borgard, C. Warren, S. Somayaji and R. Heidersbach, Corrosion Rates of Steel in Concrete, p. 174,
STP 1065, ASTM 1990.
A. Bentur, S. Diamond and N.S. Berke, Steel Corrosion in Concrete, Chapman & Hall, London, UK
1997.
www.ks.or.kr