• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.216-222
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• 2014

Chloride attack to reinforced concrete structures located in seaside can cause a serious problem of durability and maintenance during the service life. Corrosion of reinforced steel bars in concrete decreases the bond strength and finally causes the detachment of concrete cover. Polymer cement mortar is usually adopted to repair the deteriorated RC structures because of its strong bonding property. The recovered load-carrying capacity after the repair was simulated by non-linear FEM analysis. The properties of concrete, repairing materials, bonding materials and reinforced bar were used as input data. Four types of redispersible polymer powders were used as components of polymer cement mortar. Pull-off tests were carried out to examine the bond properties such as rigidity and strength. Effects of a corrosion inhibitor and the loss of reinforced bars due to the corrosion were also considered in this study. FEM modeling and analysis were conducted to propose the universal model. Physical bonding in the relationship between repair materials and steel reinforced bar is more dominant than chemical bonding.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.329-335
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• 2018

The objective of this study is to develop a mortar mixture with high workability and adhesive strength for section jacketing in seismic strengthening technology of existing concrete structures. To achieve targeted requirements of the mortars (initial flow exceeding 200 mm, compressive strength of 30MPa, and adhesive strength exceeding 1MPa), step-by-step tests were conducted under the variation of the following mixture parameters: water-to-binder ratio, sand-to-binder ratio, polymer-to-binder ratio, dosage of viscosity agent, and content of ultra-rapid-hardening cement. The adhesive strength of the mortars was also estimated with respect to the various surface treatment states of existing concrete. Based on the test results, the mortar mixture with the polymer-to-binder ratio of 10% and the content of ultra-rapid-hardening cement of 5% can be recommended for the section jacketing materials. The recommended mortar mixture satisfied the targeted requirements as follows: initial flow of 220 mm, high-early strength gain, 28-day compressive strength of 35MPa, and adhesive strength exceeding 1.2MPa.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.19-20
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• 2018

For this study, a test was conducted on the basic polymer property depending on the replacement amount of polymer. The result showed that the flow of slump was increased with the increase of polymer replacement amount and an amount of air entraining. In addition, with a decrease of unit W/B, an amount of bleeding was reduced, and the first and final time for 6% replacement amount was found to be the fastest. This implies that replacement of more than 6% may affect the hydration of cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.749-752
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• 2008

This experimental study compared polymer cement mortar with inorganic polymer binder mortar for physical properties by Si/Al mol ratio change of inorganic polymer binder. As the result of this experiment, We found that when Si/Al mol ratio goes up flexural strength and compressive strength increases but workability becomes worse. And according to the keeping them for 28 days we found that physcal property becomes worse when Si/Al mol ratio is larger than 2.61. When Si/Al mol ratio of inorganic polymer binder is from 2.43 to 2.61 compressive strength increases than over 32% after keeping for 7 days and over12 % for 28 days

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.200-201
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• 2018

The purpose of this study is to evaluate the adhesion in tension of polymer-modified mortars according to curing conditions. From the test results, the adhesion in tension is seriously affected by type of curing conditions compared with type of polymer dispersions or polymer-cement ratios. The maximum adhesion in tension of EVA-modified mortar with polymer-cement ratio of 20% cured by standard condition is about 1.81 times, the cement mortar cured in water. It is apparent that the adhesion in tension of polymer-modified mortars according to raising of polymer-cement ratio is also much more improved irrespective of type of polymer dispersions and curing conditions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.193-194
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• 2019

The purpose of this study is to design the basic mix proportions of antiwashout underwater polymer cement mortar as a repair material. The antiwashout underwater polymer cement mortars are prepared with various mix proportions using three type polymer dispersions without or with antifoamer. From the test results, the whole antiwashout underwater polymer cement mortars can be cast underwater without segregation like plain mortar. It is apparent that the flexural strength of antiwashout underwater SBR cement mortars with antifoamer at polymer- cement ratios of 5% and 10% is higher than that of plain mortar irregardless of a little low compressive strength.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.587-596
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• 2011

Ultra rapid-hardening cement is widely used for latex-modified mortar and concrete as repair and finishing material during urgent work. The purpose of this study is to evaluate the improvements in strength made to SBR cement mortars by the adding of various admixtures and by the use of different curing methods. SBR cement mortar was prepared with various polymer-cement ratios, curing conditions and admixture contents, and tested for flow, flexural and compressive strengths. From the test results, it was determined that the flow of SBR cement mortar increased with an increase in the polymer-cement ratio, and the water reducing ratio also increased. The strength of cement mortar is improved by using SBR emulsion, and is strengthened by adding metakaoline. The strength of SBR cement mortar cured in standard conditions was increased with an increase in the polymer-cement ratio, and attained the maximum strengths at polymer-cement ratios of 15 % and 10 %, respectively. The maximum strengths of SBR cement mortar are about 1.8 and 1.3 times the strengths of plain mortar, respectively. In this study, it is confirmed that the polymer-cement ratio and curing method are important factors for improving the strengths of rapid-hardening SBR cement mortar.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.330-337
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• 2021

3D printing is not only at the fundamental study and small-scale level, but has recently been producing buildings that can be inhabited by people. Buildings require a lot of cost and labor to work on the form work, but if 3D printing is applied to the building, the construction industry is received attention from technologies using 3D printing as it can reduce the construction period and cost. 3D printing technology for buildings can be divided into structural and non-structural materials, of which 3D printing is applied to non-structural materials. Because 3D printing needs to be additive manufacturing, control such as curing speed and workability is needed. Since cement mortar has a large shrinkage due to evaporation of water, cement polymer dispersion is used to improve the hardening speed, workability, and adhesion strength. The addition of polymer dispersion to cement mortar improves the tensile strength and brittleness between the cement hydrate and the polymer film. Cement mortar using polymer materials can be additive manufacturing but it has limited height that can be additive manufacturing due to its high density. When light-weight materials are mixed with polymer cement mortar, the density of polymer cement mortar is lowered and the height of additive manufacturing, so it is essential to use light-weight materials. However, the use of EVA redispersible polymer powder and light-weight materials, additional damage such as cracks in cement mortar can occur at high temperatures such as fires. This study produced a test specimen incorporating light-weight materials and EVA redispersible polymer powder to produce exterior building materials using 3D printing, and examined flame resistance performance through water absorption rate, length change rate, and cone calorimeter test and non-flammable test. From the test result, the test specimen using silica sand and light-weight aggregate showed good flame resistance performance, and if the EVA redispersible polymer powder is applied below 5%, it shows good flame resistance performance.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.11
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• pp.37-43
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• 2018

According to the evaluation of basic properties and mechanical characteristics of polymer cement mortars that contain re-dispersible type polymer, in the case of fresh mortars, flow and air content were increased due to the dispersion action of entrained air and surfactant with an increase of polymer addition ratio. In the case of mortars after hardening, flexural strength, bonding strength, absorption rate and carbonation resistance were improved due to the increased union and waterproof characteristics of internal structures as a result of the formation of polymer film.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.3
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• pp.35-41
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• 2019

In this study, the fire resistance performance of polymer cement mortars which are used as a representative repair material for section restoration, is evaluated and residual bond strength is measured by considering unity with concrete. According to the evaluation of fire resistance performance of re-emulsification type polymer cement mortars, residual compressive strength was drastically decreased according to heating temperatures with an increase of polymer addition rate, and this seems to be attributable to the application of polymer film. In addition, an explosion phenomenon occurred frequently with an increase of addition rate, so this should be considered when selecting repair materials and processing.