• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.181-188
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• 2005

Generally, high performance concrete has characteristics such as low water-cementitous material ratio, lots of unit binder powder, thus the drying shrinkage and autogenous shrinkage are tend to be increased. The purpose of this study is to investigate the effect of the glyclos based shrinkage reducing agent on the drying shrinkage and autogenous shrinkage of high performance concrete with 30% of water-cemetitious material ratio as a study to develop the technology to reduce the concrete shrinkage. Test results show that the drying and autogenous shrinkage of high performance concrete are reduced by about 20~35% at the mixing ratio of shrinkage reducing agent of 0.5%, and 1.0%, compared with plain concrete. Therefore, it analyze that the using of shrinkage reducing agent is effective to reduce the drying shrinkage and autogenous shrinkage of high performance concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.787-794
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• 2006

Generally, high performance concrete has characteristics such as low water-cementitious material ratio, lots of unit binder powder, thus the heat of hydration, autogenous shrinkage are tend to be increased. This study is to investigated the effect of the expansive additive and shrinkage reducing agent on the shrinkage properties of high performance concrete as a study to develop the reduction technology of the concrete shrinkage. Test results showed that the expansive additive and shrinkage reducing agent were effective the reduction of shrinkage of high performance concrete. Especially, the using method in combination with expansive additive and shrinkage reducing agent was more effective than the separately using method of that. Also, it analyzed that the combination of expansive additive of 5% and shrinkage reducing agent of 1% was the most suitable mixture, considering to the fluidity, strength and shrinkage properties.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.785-793
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• 2003

This study is intended to analyze the effectiveness of expansive additive, shrinkage reducing agent and combination of the two to reduce the autogenous and drying shrinkage of high performance concrete using mineral admixture such as fly ash, blast furnace slag powder and silica fume. According to results, when expansive additive and shrinkage reducing agent are mixed within an appropriate mixing ratio, fluidity and air content are not influenced, and the enhancement of compressive strength is favorable at the age of 91 and 180days. At the mixing ratio of expansive additive of 5% and 10%, the autogenous and drying shrinkage is reduced by 32∼68% and 25∼49% respectively in comparison with plain concrete. And they are reduced by 18∼34% and 16∼26% respectively at the mixing ratio of shrinkage reducing agent of 0.5% and 1.0%, compared with plain concrete. The mixture of EA-SR combined with expansive additive and shrinkage reducing agent is most effective for reduction of shrinkage. Therefore, it is considered that the using method in combination with expansive additive and shrinkage reducing agent is effective to reduce the shrinkage of high performance concrete using mineral admixture such as fly ash, blast slag powder and silica fume.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4298-4307
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• 2015

The expenses of maintenance and reinforcement for aged concrete structures are significantly on the increase as their durability and general performance has been naturally degraded. Due to this reason, interests on concrete crack reduction technology are growing but more researches are required to fulfill such fast growing demands. Particularly in the underground power facilities, it is difficult to maintain the quality of aging concrete spheres for underground power as their deterioration caused by long-term operation is on-going. In recent years, many studies have been made to overcome the issues and now it is determined that the shrinkage reducing technology which can dramatically reduce the crack at the design stage is one of the most effective solutions. In this study, the test investigated fundamental propertiesof concrete using various shrinkage reducing materials to develop low shrinkage mortar. According to results of experimental study, for mortar and concrete, glycol based material showed excellent shrinkage property and compressive strength. For the later study to generic application of the shrinkage reducing materials, performance reviews on the shrinkage reducing materials with variable factors and various materials such as changes in the amount and type of materials should be followed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1101-1104
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• 2008

Recently, active researches are conducted on high performance concrete(HPC) exhibiting high strength and high fluidity. These researches are resulting in increased applications on real structures. In order to satisfy the required performances, HPC makes use of large quantities of binder and presents low water-cementitious material ratio. Such mixing is increasing significantly the autogenous shrinkage, which subsequently is likely to favor the potential development of cracks. Therefore, we investigated the effect of used materials and mix proportions on the shrinkage properties of HPC, and of the use of expansive additives and shrinkage reducing agents on the HPC. The autogenous shrinkage of HPC using blast furnace slag are tend to be increased, in some case have the potential development of cracks by only the autogenous shrinkage. Also the using method in combination with expansive additive and shrinkage reducing agent is more effective than the separately using method of that.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.296-302
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• 2016

Studies aimed at reducing the occurrence of cracks by the shrinkage of concrete are in demand because the repair and reinforcement for cracks caused by declining concrete durability costs the user to maintain the concrete structure. In particular, in underground power facilities for power transmission, the cost is a heavy burden to repair and reinforce. For this reason, underground power facilities demanded effective methods for crack reduction at the engineering design step. This study, as a part of the development of shrinkage reducing agent for low shrinkage concrete on underground power facilities, investigated TEA to complement the shrinkage reducing agent to improve the early strength of concrete. In the case of TEA 3% as a shrinkage reducing agent, the early strength was improved significantly, and the shrinkage reducing effect was excellent. In addition, TEA 3.0 % and the shrinkage reducing agent 2.0 % showed excellent shrinkage property and compressive strength. On the other hand, more study of shrinkage reducing materials, including performance reviews on the shrinkage reducing materials with variable factors and type of materials, will be needed to generalize these results.

• Journal of the Korea Institute of Building Construction
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• v.16 no.4
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• pp.297-303
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• 2016

Shrinkage Reducing Agent(SRA) was developed in order to control drying shrinkage cracks in concrete, and the use of SRA is increasing since it can control drying shrinkage cracks and improve the quality of concrete structures. Although there are many types of prediction equations of drying shrinkage strain, there is no prediction method which can consider the effect of SRA up to the present. Therefore, it is impossible to predict the tensile stress generated by drying shrinkage of SRA concrete, and to investigate the quantitative serviceability limit state of SRA concrete. In this study, the drying shrinkage of SRA concrete was investigated by experiment and analysis in order to suggest the predictability of drying shrinkage of SRA concrete. As a result, AIJ model, ACI model, GL2000 model showed there was a correlation between the predicted values and the experimental values within the error range of ${\pm}10%$. However, CEB-FIP model and B3 model underestimated the experimental values.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.919-922
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• 2008

This paper reports the physical and shrinkage properties of concrete using expansive additive(E) and three shrinkage reducing admixtures(SRA1, 2, 3) in order to reduce shrinkage of concrete. For the properties of fresh concrete, the use of SRA1, 2, 3 results in a increase in fluidity and decrease in the dosage of super plasticizer as much as 0.05$\sim$0.1%. And For the properties of hardened concrete, the use of SRA1, 2, 3 results in a decrease in compressive, tensile and flexural strength slightly. For drying shrinkage properties, the use of SRA3 is the most effective for reduction of shrinkage, and the next best way to reduce shrinkage is combination with expansive additive(E) and shrinkage reducing admixture(SRA) or the using of expansive additive(E).

• Journal of the Korea Concrete Institute
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• v.18 no.3 s.93
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• pp.397-404
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• 2006

This paper investigates experimentally the effect of combined addition of expansive additive and shrinkage reducing agent(SRA) on setting time, compressive strength and drying shrinkage of concrete. An increase of EA and SRA content leads to a reduction in flowability, which causes the increase of superplasticizer dosage, while air content increases. For setting time, in spite of increased superplasticizer dosage, with the increase of EA and SRA, setting time shortens. This is due to the presence of alkali ion by SRA and the faster formation of ettringite. At dosage of 5.0% of EA, concrete has the highest compressive strength and above that dosage, compressive strength decreased. On the contrary, the increase of SRA dosage results in a decrease in compressive strength. Combined addition of EA of 5.0% and SRA of 1.0% shows a comparable strength with control concrete. For drying shrinkage, as expected, the increase of EA and SRA dosage leads to reduction of drying shrinkage markedly. Moreover, combined addition of EA and SRA has better drying shrinkage reduction effect than individual use of EA and SRA by as much as $5{\sim}16%$. Optimal combination of EA and SRA is fixed at 5.0% of EA and 0.5% of SRA based on the consideration of the effect of EA and SRA on fresh state, compressive strength and shrinkage of concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3535-3541
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• 2015

In this study, series of tests were performed for drying shrinkage characteristics of concrete with power type shrinkage reducing agent (SRA) and fly ash as a part of research to reduce drying shrinkage of concrete. Firstly, for the mechanical properties, a target strength was acquired securely. In the unrestraint shrinkage tests, the SRA decreased the drying shrinkage about $200{\mu}{\varepsilon}$. Lastly, in the ring tests, due to the tensile creep effect, the concrete with SRA showed the cracking times as much again as the concrete with ordinary Portland cement only did.