• KCI Concrete Journal
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• v.13 no.1
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• pp.3-9
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• 2001

This research concerns the effect of kaolin as material of cement admixture. which has the advantage of low price and high adaptability. Kaolin, a kind of soil, is well known as a raw material of pottery. which is widely scat-tered on the earth (especially in Korea). This research shows the method and process for activating kaolin to have the properties of a cement admixture through experiment. In the experiments, kaolin is baked in high temperature and then cooled suddenly to be activated. The temperature zone and time span, on which kaolin is activated are examined. The research looks over the effect of the activated kaolin based on several criteria regarding to chemical and physical characteristic of general admixtures. The results of this research are as follows; kaolin start activation at the temperature above 50$0^{\circ}C$ and make ends of activation at the temperature below 95$0^{\circ}C$ and there was little effect by the change of duration. It is concluded that compressive strength can be increased by putting activated kaolin in the concrete and the activated kaolin is good for water resistance and anti-chemical , and that it is effective for protecting the leakage of hazardous article like Cl- and for protecting damage by an organic salt like acid. The activated kaolin of proper temperature and time is effective in compressive strength, salt resistance and acid resistance. The adaptability of activated kaolin as a cement admixture was shown through this research.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.109-116
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• 2016

A flexible concrete mattress (FCM) is a structural system for protecting submarine power or communication cables under various load types. To evaluate its of protection performance, a numerical analysis of an FCM under an anchor collision was performed. The explicit dynamics of the finite element analysis program ANSYS were used for the collision analysis. The influences of the steel reinforcement modeling and collision angle of the anchor on the collision behavior of the FCM were estimated. The FCM damage was evaluated based on the results of the numerical analysis considering the numerical modeling and collision environment.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.3 s.10
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• pp.143-150
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• 2003

Recently, The corrosions of reinforced concrete structures are severe problems of economical social effects. PE-coated bars protecting from corrosion and enhancing durability of reinforced concrete structures are testified to evaluate structural properties. Tests are verified by comparative bending tests of the three type materials of epoxy coating, without coating and pe-coating. Load-deflection relations ate superior in pe-coated bar than any other materials(bare bar and epoxy bar). These are proved bonding properties enhancement by using cement powder.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.285-288
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• 2006

Recently, polymer mortar has been developed not only more improving the performance of modified mortar with polymer, but also protecting and repairing materials of structures, especially in marine environment because of their excellent performance to improve compressive strength, flexural strength, and adhesive strength. however, in fact, these rehabilitation techniques in marine environment, which consist of removing delaminated areas of concrete, cleaning affected steel and patching with polymer mortar, have proven to be ineffective for marine structures. Also, repairs are often repeated every several years. Therefore, it is neccessary to research performance evalution of chloride ion penetration of polymar mortar for section restoration.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.175-178
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• 2009

This study is thing for construction properties that protect about damage of waterproofing course that is problem in asphalt pavement and latex modification concrete pavement. It is thing about new method of construction and develop protecting material of waterproofing. Did performance test item first at, as a result, drew by suitable thing in all KS items, This is considered to have more effective spot construction work because if means that have stability by material as well as method construction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.29-36
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• 2015

In this study, to examine the use of sulfur polymer as a coating agent for concrete, durability and hazard evaluations were performed. The result of the evaluation indicated that the chemical resistance of the coating agent for concrete was outstanding against acidic, base, and alkaline solutions. The evaluation of the bond strength after an accelerated weathering test depending on the mixing condition indicated that the most outstanding strength characteristic was obtained when silica powder and fly ash were mixed at the same time. The bond strength exceeded 1 MPa in every mixing condition even after the repeated hot and cold treatment of the coating agent specimen for concrete, and the SFS mix proportion showed the highest bond strength. The examination of the accelerated carbonation and chloride ion penetration resistance of the concrete coated with the coating agent indicated that the specimen coated with the coating agent using silica powder as a filler showed the most outstanding durability. When a fish toxicity test was performed to examine the hazard of the use of the functional polymer as a coating agent for concrete, the functional polymer was found to have no effect on the organisms. When the chemical resistance, freezing and thawing resistance, carbonation, and chloride ion penetration resistance of the coating agent were considered, substituting silica powder and fly ash as the fillers of the functional polymer by 20%, respectively, was the optimal level in the range of this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.155-163
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• 2007

High Strength Concrete (HSC) has weakness that in a fire, it is spalled and brittles. The phenomenon of spalling is made by water vapor's (resulting from evaporation in the material at over $100{^{\circ}C}$)' being confined in watertight concrete. As the concrete strength increases, the degree of damage caused by the spalling becomes more serious because of the permeability. It is reported that the polypropylene(PP) fiber has an important role in protecting concrete from spalling and the optimum dosage of PP fiber is 0.2%. This study was conducted on the nonreinforced concrete specimens. The high-temperature behavior of high-strength reinforced concrete columns with various concrete strength and various dosage of PP fibers was investigated in this study. The results show that the ratio of unstressed residual strength of columns increases as the concrete strength increases and the ratio of unstressed residual strength of columns increases as the dosage of PP fiber increases from 0% to 0.2%, however, the effect of fiber dosage on residual strength of column barely changes above 0.2%.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.211-216
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• 2003

Coated bars are protecting reinforcing bars from corrosion and enhancing durabilities of reinforced concrete structures are tested to evaluate corrosion protection properties. Tests are performed based on the relevant standards of ACI and ASTM, such as chemical resistance, salt water spray, salt crack test and chloride permeability test with the main variable of the coating thickness. Three type materials are tested by Polyethylene, epoxy and bare bar. Test results show good chemical protection property and chloride permeability. Polyethylene coated bar is good coating material than any other materials.

• Magazine of the Korea Concrete Institute
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• v.6 no.6
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• pp.173-179
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• 1994

Epoxy coated bars protecting reinforcing bars from corrosion and enhancing durability of reinforced concrete structures are tested to evaluate corrosion protection properties. Tests are performed based on the relevant sta.ndards of KS and ASTM, such as chenical resistance, salt water spray, salt crock test and chloride ermeability test. with the main varlable of the coating thlckness. Test results show good chemical protection property and chloride permeability. The results of the salt water spray and the salt crock test show that epoxy coating well protects the reinforcing bars from corrosion, cornparing to the biack bars without epoxy coatmg. However, several spots on the coated bars are rusted at the pinholes or un the bars with coating thickness less thar $200{\mu}M$. Special cautions are required i n the process of blast cleanmg when applying the usion-bonded epoxy coating.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.161-168
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• 1998

Increase of traffic volume in recent years results in deterioration of the bridge slab, which is directly subjected ot vehicle loads. Where extensive repair is necessary, replacement or enhancement of load carrying capacity using full depth precast concrete deck is often the most practical solution. Precast deck system has transverse joints between adjacent precast decks. Vertical shear forces occur when a vehicle wheel load is carried by precast decks and the joints are used to transfer the load to an adjacent deck. Effective load transfer between precast decks is critical for integral behavior. Finite element analysis and tests were run on the proposed femal-to-female type joint. 18 joint specimens were tested to investigate the effects of angle. D/H, and confining stress under static load. Results indicate joint with angle of 60$^{\circ}$ and D/H of 1/4 shows the improved load carrying capacity on crack. It is effective in protecting the cracking of joints to keep the joint in compression using confining stress.