• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.231-236
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• 1998

In general, the drying shrinkage of polymer-modified mortars using redispersible polymer powders is much higher than that of unmodified mortar. The purpose of this study is to reduce the drying shringkage of polymer-modified mortars using a redispersible poly(ethylene-vinyl acetate) (EVA) powder, which is widely used for the manufacture of prepackaged-type polymer-modified mortar products at present. Polymer-modified mortars using the redispersible EVA powder with powdered shrinkage-reducing agent were prepared with various polymer-cement ratios and shrinkage-reducing agent contents, and tested for drying shrinkage and strength. From the test results, the drying shrinkage of the redispersible EVA powder-modified mortars with a powdered shrinkage agent is remarkably reduced with increasing shrinkage-reducing agent content, and becomes approximately a half of that of the redispersible EVA powder-modified mortars with the same polymer-cement ratios and without the shrinkage-reducing agent at a shrinkage-reducing agent content of 6%.

• Journal of the Korea Institute of Building Construction
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• v.7 no.3
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• pp.123-130
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• 2007

This study investigated the fundamental properties and shrinkage properties of high performance concrete with water/binder ratio of 0, 30 and with combination of expansive additive and shrinkage reducing agent. According to the results, the fluidity of high performance concrete showed lower the using method in combination with expansive additive and shrinkage reducing agent than the separately using method of that, so the amount of superplasticizer increased when the adding ratio of expansive additive and shrinkage reducing agent increased. However the air content of concrete increased when used in combination with expansive additive and shrinkage reducing agent, so the amount of AE agent decreased. The compressive strength showed the highest at 5% of expansive additive, and decreased with an increase of the amount of shrinkage reducing agent. Furthermore, in order to reduce the shrinkage of high performance concrete, it was found that the using method in combination with expansive additive and shrinkage reducing agent was more effective than separately using method of that. Autogenous shrinkage was predicted using JCI model. Because JCI model is unable to consider the effect of EA and SRA, correction factor should be added to enhance the accuracy.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.165-168
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• 2002

The effects of polymer-cement ratio, antifoamer agent content and shrinkage-reducing agent content on the drying shrinkage of polymer-modified mortars using redispersible polymer powder are examined. As a result, irrespective of the antifoamer content, the drying shrinkage of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content. Such a drying shrinkage development is due to the effect of reducing water from incorporation of EVA redispersible polymer powder and antifoamer agent.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.929-932
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• 2006

The effects of polymer-binder ratio, antifoamer content and shrinkage-reducing agent content on the setting time and drying shrinkage of high-fluidity polymer-modified pastes are examined. As a result, the setting time of the high-fluidity polymer-modified pastes tends to delayed with increasing polymer-binder ratio. Irrespective of the antifoamer content, the drying shrinkage of the high-fluidity polymer-modified pastes tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.368-373
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• 1998

Prepackaged system consists out of a dry mix which contains cement, sand, redispersible polymer powder and admixtures in the right proportions. The purpose of this study is to evaluate the quality of prepackaged-type polymer-modified mortar products using redispersible poly(ethylene-vinyl acetate)(EVA) powder. Polymer-modified mortars using the redispersible polymer powder with powdered with powdered shrinkage-reducing agent were prepared with cellulose fiber contents of 0, 0.5, 1.0% and shrinkage-reducing agent contents of 0, 4%, and tested for drying shrinkage, strength, adhesion in tension, water absorption. From the test results, the prepackaged-type polymer-modified mortar products with 4% of shrinkage-reducing agent content give good properties. and that their properties largely depends on the shrinkage-reducing agent content rather than the cellulose fiber contents.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.362-367
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• 1998

The purpose of this study is to examine the influences of polystyrene content and St/UP on the setting shrinkage and strengths of polymer mortar with waste expanded polystyrene resin as a shrinkage-reducing agent, and to recommend the optimum binder formulations for product of low-shrinkage polymer mortar. In this paper, polymer mortar is prepared with waste expanded polystyrene content and St/UP, and tested for setting shrinkage, flexural and compressive strengths. From the test results, irrespective of increasing of waste expanded polystyrene resin, the strengths reduction of polymer mortar with waste expanded polystyrene(EPS) resin is not recognized. And the setting shrinkage is reduced with EPS resin content. The waste expanded polystyrene resin as a shrinkage-reducing agent can be used in the same manner as commercial polystyrene resin. In this study, we can obtain the optimum mix proportions of polymer mortar using EPS resin.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.1
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• pp.51-60
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• 2006

This study was conducted to investigate experimentally the drying shrinkage and the strength properties of redispersible SBR and PAE powder-modified mortars. Polymer-cement ratio, content of shrinkage-reducing agent and antifoamer content were manipulated as the experimental variables. The peculiarity of this study is to obtain a high early-age strength by using the portland cement and alumina cement with the ratio of 8 : 2. Until 7 days of age, the drying shrinkage remarkably increased up to $1\~2\times10^{-4}$, while it tended to decrease as the ratio of polymer to cement ratio and the content of shrinkage-reducing agent increased. Polymer-cement ratio was effective in improving the flexural, tensile and adhesive strengths: As the ratio increased, the strengths correspondingly increased. The flexural strength was in the range of $7\~11$ MPa, the tensile strength was $3.5\~5$ MPa and the adhesive strength was $1.2\~3.9$ MPa. On the other hand, the compressive strength tended to decrease as the polymer-cement ratio increased, and it was in the range of $23\~39$ MPa. All strengths, flexural, tensile, adhesive and compressive strengths, decreased as the content of powder shrinkage-reducing agent increased. It turned out that the polymer-cement ratio influenced more on the behavior of drying shrinkage and the properties of strength than the powder shrinkage-reducing agent did.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.93-98
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• 2002

The effects of polymer-cement ratio, antifoamer content and shrinkage-reducing agent content on the air content, setting time and drying shrinkage of polymer-modified mortars using redispersible polymer powder are examined. As a result the air content of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and antifoamer agent content. Regardless of the antifoamer content, the setting time of the polymer-modified mortars using redispersible polymer powder tend to delayed with increasing polymer-cement ratio. Irrespective of the antifoamer content, the drying shrinkage of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.61-64
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• 2004

This study is to investigate the engineering and shrinkage properties of concrete incorporating shrinkage reducing agent(SRA) and expansive additive(EA) in order to reduce shrinkage of concrete. According to results, as for the properties of fresh concrete, increase in, SRA and EA content leads to reduce the fluidity but to increase the air content, and as for setting time, there is little difference. For strength properties, it decreased with an increase in SRA dosage and increased up to 5% of EA content. For the properties of drying shrinkage, it shows decline tendency with an increase in SRA and EA content reiteratively. It alto reduces significantly with the combination of SRA-EA systems due to the combined effect of the admixture. In the scope of this paper, it is found that the use of SRA with 0.5％ and EA with 5% has optimum effects on the various properties of concrete. And under the combination of SRA and EA, it can reduce drying shrinkage about 37%.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.925-928
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• 2006

The effects of polymer-binder ratio, antifoamer content and shrinkage-reducing agent content on the air content and strengths of high-fluidity polymer-modified pastes are examined. As a result, the air content of the polymer-modified pastes tends to decrease with increasing polymer-binder ratio and antifoamer content. Irrespective of the antifoamer content, the flexural and tensile strengths of the high-fluidity polymer-modified pastes tends to increase with increasing polymer-binder ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the polymer-modified pastes decreases with increasing polymer-binder ratio and shrinkage-reducing agent content.