• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.357-362
• /
• 1997

The purpose of this study is to evaluate the adhesion of concrete pipe lining using polymer mortar. The polymer mortars with various mix proportions are prepared, and tested for flexural and compressive strengths, adhesion in tension, and the aspects of lining surface and workability are evaluated. Form the test results, it is apparent that the appropriate polymer mortars of lining to concrete pipe can be produced. The flexural and compressive strengths of polymer mortar for lining are affected by type of resin, and aggregates content, and water content at the surface of concrete pipe is important factor for improvement in adhesion of polymer mortar. It is obvious that the economical polymer mortars having an excellent cost performance ration can be produced through this study.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10b
• /
• pp.1267-1272
• /
• 2000

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. These are problems on cold weather concrete. One of the solution methods for resolving these problems has been to reduce the freezing temperature of concrete by the use of chemical admixtures called Accelerators for freezing resistance. Therefore, in this study, we executed freezing temperature of mortar, setting and strength properties with using water reducing accelerator and accelerators for freezing resistance which are producted internationally. As a result of this experiment, the freezing temperature of mortar is lower and the setting property is promoted when the admixing content of accelerators for freezing resistance is increased. Moreover, the compressive strength of mortar used accelerators for freezing resistance represented the result which is similar with result of analysis of compressive strength increase with using logistic curve formula, but in the case of plain and using water reducing accelerator, there is no relation between logistic curve formula, maturity and compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.21-22
• /
• 2022

High fluidity concrete has excellent workability, and if the cross-section of the building is complicated, it is possible to place good quality concrete and increase the construction speed, so its utility value is very high. However, it is premised on the accuracy of concrete formwork assembly. Concrete leakage through formwork gaps is an important consideration when applying high flow concrete. In order to quickly solve the leak of high fluidity concrete caused by formwork gap occurring at the site by accelerator injection, we proceeded with research to confirm the possibility of reducing the amount of formwork leakage of high fluidity mortar. It was confirmed that the injection of the accelerator could reduce the amount of mortar leakage.

• Journal of the Korea Concrete Institute
• /
• v.16 no.5 s.83
• /
• pp.613-620
• /
• 2004

We encapsulate the core materials which have long term resisting properties to the insect. We also try to apply those capsules to the mortar and concrete which is used for the structures and ornament materials. Various membrane structures and sizes of microcapsule are tested and construction properties of the mortar and concrete which contain microcapsules are examined. The capsuled are confirmed by SEM and optical microscope. Finally the microcapsules with anti-insect which can be used for the mortar and concrete are developed through the various experiments and mock-up tests.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.180-183
• /
• 2004

In general, the polymer is mainly used with the cement mortar with various admixtures for concrete repair. The properties of cement-polymer mortar was studied by the cement-polymer ratio only and ignored any influence of admixtures in the mortar. Therefore in this study, the test is carried out with 2 product of polymers(the same type produced by different companies) and various admixtures. It is found that the same type of polymers produced by different companies affect the properties of fresh and hardened concrete. As increasing the polymer proportion in mortar, the compressive strength and flexural strength are increased, and also drying shrinkages is increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.220-223
• /
• 2004

It is fact that the cement is the most important material to harden the mortar and concrete, and Potland cement is used widely. Also, the chemical and physical properties of cement are different according to the kinds of cement. This is an experimental study to compare and analyze the influence of cement strength on the compressive strength of mortar to improve the quality of mortar and concrete. According to test results, it was found that correlation between cement strength and mortar strength was very high in all mixture.

• International Journal of Concrete Structures and Materials
• /
• v.10 no.1
• /
• pp.61-73
• /
• 2016

In predicating the probability distribution of chloride diffusion coefficient of recycled aggregate concrete ($D_{RAC}$), the morphological characteristics of three phases, i.e., the old attached mortar, the natural aggregate and the new mortar, should all be taken into account. The present paper attempts to develop a probability density evolution method (PDEM) to achieve this. After verifying the derived PDEM results with experimental results, the effects of old attached mortar to the $D_{RAC}$ are examined in a quantitative manner. It is found that (1) the variation of the attached mortar content is much sensitive to $D_{RAC}$; (2) given the probability distribution of the content and chloride diffusion coefficient of old mortar, the probability distribution of DRAC can be analysed based on the PDEM; and (3) the critical chloride diffusion coefficient at a certain assurance rate can be obtained by the PDEM. The analysis results of this investigation will be valuable to the durability design for RAC.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.17-22
• /
• 2002

Chloride ions have a tendency to penetrate into concrete and proceed the corrosion by depassivating rebar surface. Thus the deteriorated concrete is subject to experience severe degrading of durability under marine environment. Physical properties of mortar, such as, compressive strength and penetration depth of chloride ion were investigated. And to investigate the effect of containing SG, FA in mortar, the diffusion coefficient of chloride was measured through an electro - migration test. The diffusion coefficient of chloride was decreased with the increase of replacement ratio of SG compared with plain specimen.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.888-895
• /
• 2000

As conventional grouting materials for the sheath such as cement slurry or cement-mortar are mixed and pumped in site, those harden with bleeding or shrinkage and meets low compressive strength. Also the materials haven't always same cements, sand size distributions, additives in site, so those materials have unstable quality properties. We have studies on ready-mixed-mortar for grouting pretensioned or post-tensioned cables and rods to encapsulate the steel so that we have developed a formulation of specially selected, flowable, shrinkage-compensating materials.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.04a
• /
• pp.19-22
• /
• 1991

In order to the Utilization of Fly ash, The Properties of cement Mortar use of Fly ash based on Mixing rate, strength of mortar, W/C+F and quantity of Fly ash, Flow value, and unit weight are investigated. So follow result are unit weight of mortar of Fly ash is about 2014 Kg/㎥, Compressive strength of mortar is 50-404 Kg/$\textrm{cm}^2$ and beneficial reference to the utility of domestic Fly ash were obtained.