• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.330-335
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• 1999

The objective of this stu요 was to develop a polymer mortar guide block for the blind handicapped people. A high strength and a long durability polymer concrete using unsaturated polyester resin was used to developed the block and to improve the exiting cement mortar guide bloc. Physical and mechanical properties of the polymer mortar guide block were investigated with respect to absorptivity, impact strength, bending strength compared to those of the conventional cement guide block. The polymer mortar guide block was proven to have properties , indication that the block have better industrial applications.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.117-124
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• 2017

In this study, to evaluate the setting time, compressive strength and drying shrinkage of ordinary Portland cement and Portland blast-furnace slag cement mortar with 0, 10, 20, 30 wt.% alpha-calcium sulfate hemihydrate. As a results, as the replacement ratio of alpha-calcium sulfate hemihydrate increased, the initial setting time of ordinary Portland cement and Portland blast-furnace slag cement mortar was faster. In addition, the compressive strength decreased with increasing replacement ratio of alpha-calcium sulfate hemihydrate in both ordinary Portland cement mortar and Portland blast-furnace slag cement mortar. The strength development of Portland blast-furnace slag cement mortar with alpha-calcium sulfate hemihydrate was effective than that of ordinary Portland cement mortar. On the other hand, in the case of the mortar with alpha-calcium sulfate hemihydrate, it was confirmed that shrinkage deformation was reduced at the early age by growth pressure of needle-shaped ettringite crystals produced by incorporation of alpha-calcium sulfate hemihydrate. However, the effect of inhibiting shrinkage deformation of mortar with alpha-calcium sulfate hemihydrate was not significant as the age passed. Therefore, it is considered that the alpha-calcium sulfate hemihydrate is useful as a construction material.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.319-322
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• 1999

The adhesion properties of polymer cement mortars for cement concrete repair were evaluated with respect to polymer-cement ratios and the surface conditions of cement concrete substrate. Styrene-butadiene rubber (SBR) was used as an additive for polymer cement mortars. The adhesion strength of cement mortar was smaller than that of polymer cement mortar. The adhesion strengths to the dry surfaces of substrate were larger than those to the wet surfaces, indicating that the dryness of substrate increased the adhesion strength in repairing concrete structures.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.597-606
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• 2022

This paper examined the effect of water repellent type and addition among various factors on the deicing performance of cement mortar surface according to incorporation. As a result, the compressive strength of the water repellentcement mortar compared to the cement mortar, and the compressive strength of the oligomer-based water repellent mortar was higher than that of the monomer-based water repellent. The contact angle of the water-repellent mortar was increased compared to the additive mortar, and the oligomer water-repellent agent compared to the monomer-based water-repellent. As a result of measuring the ice formation time of cement mortar due to the mixing of the water repellent, the ice formation was delayed until 25 minutes for mortar to which the water repellent was added. the measurement of the ice attachment load mortar without water repellent with water repellentwhen the water repellent was added to mortar, deicing performance was increased.

• Journal of the Korea Institute of Building Construction
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• v.14 no.1
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• pp.94-101
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• 2014

Approximately 240,000 tons of waste shells are produced annually in the south and west coast of South Korea. Some of these waste shells (oyster, cockle) are recycled as seeding collector and fertilizer, but most are dumped illegally near the coast. One of the alternative solutions that can economically utilize a large amount of these waste shells is to apply them to the production of construction materials. In this research, the basic physical properties of waste shells such as oyster, cockle, clam, manila clam were investigated, and were used to prepare cement mortar with a 25% replacement ratio of sand. According to the results, the 28 day compressive strength of cement mortar with cockle and manila clam shells was similar to that of plain cement mortar. The compressive strength decreased by about 18% when clam was used. However, the cement mortar with oyster shell showed about a 35% reduction in 28-day compressive strength, and two times the absorption capacity of plain cement mortar. The reduction in compressive strength and the increase in absorption capacity were mostly associated with the porous nature of the oyster shell.

• Korean Journal of Construction Engineering and Management
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• v.1 no.2 s.2
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• pp.63-70
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• 2000

Since inorganic pigment, among admixtures used for cement composites, can raise the esthetic value of a building due to its effect of coloring, it can be assumed that the quantity consumed is expected to increase in connection with the recent trend of emphasizing the beautiful sights of the city. We carried out a flow test by changing the mix proportion of the cement mortar mixed with an inorganic pigment, water-cement ratio and pigment mixing ratio in order to present the basic materials for utilizing colored cement mortars. In construction by exploring the effect of inorganic pigments on the workability of cement mortar. In case of red pigment mortar and yellow pigment mortar, the workability was found to be rapidly decreased. To secure proper workability, it is necessary to increase the amount of mixing water, or to use superplasticizer. In case of green pigment mortar, however, it recorded $-2.4{\~}6.9{\%}$, showing that there was almost no change in flow. In case of black pigment mortar, it was also confirmed that there is no need to consider workability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.15-22
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• 2017

This study focuses on the investigation of bond strength of magnesium potassium phosphate cement mortar(MKPC) according to moisture condition of substrate. Tensile bond test, shear bond test and interfacial bond test are adopted for evaluating the adhesion characteristics of MKPC to conventional cement mortar substrate. The main experimental variables are test methods and moisture levels of substrate. Because the moisture condition of the substrate may be critical to achieving bond, optimum moisture condition for a conventional concrete substrate has evaluated in this study. The results are as follows ; The effects of moisture condition at substrate into the bonding of MKPC are less different than polymer cement mortar and epoxy mortar. But the saturated and surface dry condition is the most appropriate moisture level among the considered, followed by saturated condition and wet condition. Thus, an adequate moisture level of substrate for MKPC is essential for good bond strength.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.152-161
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• 2024

This paper investigates the manufacturing and fundamental quality characteristics of potassium magnesia phosphate-based non-cement high-volume fly ash repair mortar. To derive the optimal mix for non-cement mortar, the manufacturing characteristics were evaluated based on the magnesia ratio, and the mortar manufacturing characteristics were assessed with the fly ash mixture. Additionally, the non-cement magnesia repair mortar was produced considering the effects of fly ash mixture and basalt fiber. The evaluation results determined the optimal mix of non-cement magnesia repair mortar, and the feasibility was examined through workability and fundamental quality assessments. The optimal magnesia ratio was found to be P:M 1:0.5, with W/B at 30 %. It was also confirmed that mixing FA and basalt fiber improves fiber dispersion and workability. Even with over 50 % FA mixture, the target strength was achieved within six hours, with a flow increase of up to 18 % and a flexural strength decrease of about 1-2 MPa.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.589-592
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• 2006

The growth in concrete structure repair has prompted major efforts to develop high early strength concrete. So, we were examined fundamental properties of cement mortar using the ordinary portland cement with rapid-setting cement. The experiments were carried out to investigate the characteristics of rapid-setting cement according to the blended ratio. The containing ratio of rapid-setting cement were changed five steps (20, 30, 50, 70, 100%) and then the flow value, setting time, compressive and bond strength test of cement mortar with RSC were investigated in this study.

• 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.