• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.4
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• pp.35-41
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• 2007

The most agricultural concrete structures for the irrigation and drainage are exposed to the underwater condition at the irrigation period and they take the influence on very severe cold in the winter. Therefore, it is impossible to use repair materials used to the general concrete structures. The research need the development of the repair material for a performance enhance of the agricultural underwater concrete structures. This research evaluated the mechanical and durability performance of the latex modified repair mortar for underwater concrete structures which peformed the repair in the underwater according to the characteristic of the agricultural concrete structure. The latex modified repair mortar is a material that minimize the effect of the ecosystem, environment and the segregation. In this research, the construction condition of the latex modified repair mortar for agricultural concrete structures was considered and the test specimens made in the underwater condition. Test results was then compared with target performance and commercial repair mortar. Experimental test results indicated that the mechanical and durability performance of latex modified repair mortar for agricultural underwater concrete structure satisfied all target performance. Also, the latex modified repair mortar resulted in better repair performance than the commercial repair mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.297-300
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• 2006

Recently, To extend building's life, the use amount of repair mortar has been rapidly increased and naphthalenesulfonic and melanminesulfonic, polycarboxylic superplasticizer etc. are used for repair mortar in large numbers of construction site for efficient work. In this study, it was going to examine the use proper of superplasticizer for repair mortar through the hydrate setting time test and flow test with the mortar combination which replaced by alumina cement and added superplasticizer. As a result, the fluidity of the mortar replaced by alumina cement(10%) and added superplasticizer was dropped down and setting time was shortened. Especially this appearance was more increased on the mortar combination added ploycarboxylic and melanminesulfonic superplasticizer than naphthalensulfunic superplasticizer.

• International Journal of Concrete Structures and Materials
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• v.2 no.1
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• pp.27-33
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• 2008

Most of existing repair materials have some shortcomings such as brittle fracture, imperfect interface bonding and marked difference in modulus of elasticity compared with the structures. These problems make their repair inefficient. Some researches on using a fiber-reinforced mortar as an alternative to enhance the efficiency have been carried out recently. This paper presents the results of an experimental study on the performance of sprayed PVA fiber-reinforced mortar as a repair material. We evaluated its mechanical properties, durability and strengthening effect. This study shows that the sprayed PVA fiber-reinforced mortar is remarkably effective as a repair material.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.67-68
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• 2021

In this study, Repair mortar was prepared using CNT powder with improved dispersibility and its characteristics were analyzed. As a result of the experiment, the compressive strength and flexural strength were found to be at similar levels compared to Plain without CNT. In addition, as a result of the drying shrinkage test, it was found that the drying shrinkage amount was decreased due to the effect of CNT mixed into the porous material filling the internal pores of the repair mortar.. The Bond strength of the repair mortar was at a similar level regardless of whether CNT was added or not

• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.45-53
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• 2011

This study was performed to develop repair and reinforcing materials in sewage drain pipe by using 40% of CAC(Calcium Aluminate Cement) and 4% of Polymer Powder. Regarding reinforcing materials to enhance load-bearing capacity, polyester textile and wire mesh were adopted and then they were evaluated by the measurement of deflection and Stress-strain Relationship. Two types of drain pipe made by concrete and PE were considered as plain specimens and then loading test were performed after repaired by CAC mortar impregnated reinforcing materials. As the test results of the load-bearing test on both drain pipe, there was higher load-bearing capacity on the specimen adopted wire mesh but debonding of repair mortar was found due to stiffness of wire mesh. By the way, repair system using CAC mortar impregnated polyster textile without wire mesh showed satisfactory results including bonding and load-bearing capacity regardless substrate, so this repair system using by mixture of CAC mortar and polyster textile is suggested as the reasonable repairing method within this experimental scope.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.309-312
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• 2006

In this study, the repair method using PVA fiber reinforced mortar evaluated on durability performance. Test items are compressive strength, flexural strength, carbonation, freezing-thawing. As for the test results, it was found that durability performance of the repair method using PVA fiber mortar showed more better than the existing repair method. Therefore, appling on the repair method using PVA fiber mortar, the repaired concrete structures can be increased to service life.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.621-624
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• 2006

In this study, the repair method using PVA fiber reinforced mortar evaluated on durability performance. Test of salt injury, carbonation, freezing-thawing, chemical attack, permeability was performed As for the test results, it was found that durability performance of the repair method using PVA fiber mortar showed more better than the existing repair method. Therefore, appling on the repair method using PVA fiber reinforced mortar, the repaired concrete structures can be increased to service life.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.5
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• pp.23-30
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• 2007

This research was to evaluate the shrinkage and durability performance of latex modified repair mortar and to improve the service lift of the agricultural concrete structures. The shrinkage characteristics of the repair material creates the delamination of repair materials and existing concrete. It may reduce the service life of structures. Also the reduction of durability performance of the repair materials induces the destruction of the repaired concrete structures at early stage. In this research, plastic and drying shrinkage, thermal expansion coefficient for shrinkage properties, durability performance, permeability, repeated freezing and thawing, and resistance of chemical solution test were performed. Test results showed that the latex modified repair mortar indicated the shrinkage amount which the delamination does not happen, and the latex modified repair mortar appeared excellent long-term durability performance which can increase the service life.

• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.349-356
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• 2006

At present, the selecting system and analytic estimation criterion on repair materials and methods of the deteriorated RC structures have not yet been set up in domestic. Under these circumstances, deterioration such as shrinkage crack, corrosion of rebar has been often occurred after repair, and this finally results in too frequent repairs. In this study, three types of repair methods were experimentally investigated by the accelerating test in a combined deterioration chamber and long-term field exposure test. Three types of repair methods applied in this study belong to a group of polymer cement mortar, which is commonly used in repair works. According to the results of this study, durability of repair mortar layers and corrosion properties of recovered rebar could be investigated in short period by the accelerating test in a combined deterioration chamber, which can simulate the condition of repeated high-and-low temperature and repeated dry-and-wet environment, spraying chloride solution and emitting $CO_2$ gas. After 36 month long-term filed exposure test in the coastal area, harmful macro-cracks are observed in the polymer cement mortar layer of some repair methods. These crack are considered to result from drying shrinkage of polymer cement mortar. Also, after 36 month exposure, amount of corrosion area and weight loss of rebar are found to be different according to the types of repair methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.617-620
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• 2006

The EVA polymer is used as a modifier in the repair mortar, which contains various admixtures and mineral admixtures. It has been reported that the effect of polymer in cement mortar by the cement-polymer ratio only, but effect of admixtures over the polymer mortar was unknown. In this study, the fresh and mechanical properties of polymer cement mortar influenced by the range of silica fume ratio were investigated. It was found that with increasing the ratio of silica fume, mechanical properties(compressive strength, flexural strength, adhesive strength) of repair mortar is improved and drying shrinkage is increased.