• International Journal of Highway Engineering
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• v.20 no.3
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• pp.11-18
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• 2018

PURPOSES : Durability of concrete is traditionally based on evaluating the effect of a single deterioration mechanism such as freezing & thawing action, chloride attack, carbonation and chemical attack. In reality, however, concrete structures are subjected to varying environmental exposure conditions which often results in multi-deterioration mechanism occurring. This study presents the experimental results on the durability of concrete incorporating air-cooled slag(AS) and/or water-cooled slag(WS) exposed to multi-deterioration environments of chloride attack and freezing & thawing action. METHODS : In order to evaluate durable performance of concretes exposed to single- and multi-deterioration, relative dynamic modulus of elasticity, mass ratio and compressive strength measurements were performed. RESULTS :It was observed that multi-deterioration severely affected durability of concrete compared with single deterioration irrespective of concrete types. Additionally, the replacement of cement by AS and WS showed a beneficial effect on enhancement of concrete durability. CONCLUSIONS : It is concluded that resistance to single- and/or multi-deterioration of concrete is highly dependent on the types of binder used in the concrete. Showing the a good resistance to multi-deterioration with concrete incorporating AS, it is also concluded that the AS possibly is an option for concrete materials, especially under severe environments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.101-102
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• 2023

This study aims to mix the base concrete by mixing latex to improve the durability performance to reduce the composite deterioration of the base concrete. Latex fiber has high resistance to freezing and thawing, adhesion, and deicing agent (calcium chloride), and it is used to secure long-term durability to reduce cracking and compound deterioration of concrete. In addition, through experiments, we are trying to find ways to improve the strength of concrete by studying the mixing of the appropriate mixing ratio of latex.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.321-324
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• 2006

The latest concrete has showed that the deterioration of durability has been increased by the damage from salt, carbonation, freezing & thawing and the others. Therefore, it is needed to protect durability and performance according to the appropriate materials and methods in the concrete structures. In general, several types of polymer and silicate are used as protecting deterioration agents of concrete structures, but these agents have many problems because of low durability and properties. In this study, It developed the deterioration restraining agent using polycondensed silicate and monomer that can block a deterioration cause such as CO2 gas, salt and water from the outside and enhance waterproofing ability by reinforcing the concrete surface when applying it to concrete structures. Also, it evaluated improving concrete performance using a deterioration restraining agent.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.334-338
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• 1995

In recent years, the prediction of the deterioration rate of concrete structures has become major research interest. However, there are still many uncertain factors in the deterioration process and the relation between deterioration and durability of structures. This is mainly due to various uncertainties involved in the construction process and the environmental conditions which affect the rate of deterioration of concrete structures. In this study a limit state model in terms of random crack width due to applied dead and live loads is proposed for the assessment of crack damage of reinforced concrete structures. The AFOSM reliability method is used for the reliability evaluation of the crack durability of concrete bridges. The proposed model for crack durability of concrete bridges is applied to the Seoul interior circuit elevated expressway. The sensitivity analyses are performed for the proposed model.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1127-1134
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• 2009

Concrete has three major properties after a penetration-reinforcing agent is applied on its surface. First, the durability is improved by the sol-gel process of synthesized material from the polycondensation of TEOS (tetra-ethoxyorthosilicate) and acrylate monomer. Second, the capability to absorb impact energy is reinforced through the formation of a soft and flexible layer of organic monomers by Tea (Tetra Ethyl Amin). Third, the capability to prevent deterioration is enhanced by adding isobutyl-orthosilicate and alcohol. The performance and application of an agent developed through the synthesis of organic and inorganic material in an effort to prevent concrete from deterioration and improve the durability of concrete structures were verified in diverse experiments. The results of these experiments showed that the application of the proposed penetration-reinforcing agent has the effect of increasing the compressive strength by filling up the internal pores of concrete with physically and chemically stable compounds after penetrating the concrete. It also improves the durability against the deterioration factors such as salt water damage, carbonation, freezing and thawing, and compound deterioration. Therefore, it is confirmed that the penetration-reinforcing agent is a useful substance for the management and repair of concrete structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.131-140
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• 2001

In general, the deterioration induced by the freezing and thawing cyclic in concrete structures often leads to the reduction in concrete durability by the cracking or surface spalling. If it can prediction of concrete deterioration subjected to cyclic freezing and thawing, we can rationally do the design of mix proportion in view of concrete durability and the maintenance management of concrete structures. Therefore in this study a prediction method of deterioration for concrete structures subjected to the irregular freezing and thawing is proposed from the results of accelerated laboratory freezing and thawing test using the constant temperature condition and the in-situ weathering data. Furthermore, to accurately predict the concrete deterioration, a method of modification for the effect of hydration increasing during rapid freezing and thawing test is investigated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.171-175
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• 2010

This paper presents the experimental results of frost durability characteristics including freezing-thawing and de-icing salt scaling of the concrete for gutter of the road and marine structure. Mixtures were proportioned with the three level of water-binder ratio(W/B) and three binder compositions corresponding to Type I cement with 0%, 30% and 50% GGBS(Ground granulated blast furnace slag) replacement. Also, two different solutions of calcium chloride were used to evaluate their effect on the frost durability resistance. Specially, in case of complex of freezing and thawing with salt and carbonation, the deterioration of concrete surface is evaluated. Test results showed that the BFS30 and BFS50 mixture exhibited higher durability and lower mass loss values than those made with OPC mix and the use of GGBS can be used effectively in terms of economy and frost durability of the concrete to be in complex deterioration. Therefore, the resistance to complex deterioration with freezing-thawing was strongly influenced by the strength and the type of cement.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.61-74
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• 2003

This study(II) apply to the A city by using the optimal rehabilitation model based on the deterioration prediction of the water distribution system proposed the study(I). The deterioration prediction model divides factors into 14 factors with digging and experiment and 9 factor without digging and experiment and calculate the deterioration degree. The application results of the deterioration prediction model show that a difference of the deterioration degree according to factor numbers is within 1~2%. Also, the model can predict the deterioration degree of each pipe without digging and experiment. The optimal rehabilitation model is divided into the optimal residual durability of each deterioration factor and budget constraint or not. The application result is as follow: the rehabilitation time and cost increase according to the increasing of the optimal residual durability. When compared the model with budget constraint and model without budget constraint, the former model increase the cost of total contents. In case of budget constraint, the increasing tendency is concluded that the pipe rehabilitation is executed in same budget every year in condition that every rehabilitation cost do not exceed the every year budget within the optimal residual durability.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.372-375
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• 2004

Scaling deterioration and resistance to freezing of port concrete structures due to the combined effects of chemical actions by containning chlorides and the freeze-thaw action is also a problem which has not yet been fundamentally solved. Furthermore, deterioration of concrete surface was considered as accelerate factor of concrete durability tended to decrease. Therefore, we considered the scaling measuring method and decreasing influence of durability of concrete according to kind of binders, such as OPC, Slag, Slag+Fa, due to freeze and thaw of concrete by containing chlorides. As a results of this study, it was effective method of scaling deterioration and resistance freewing of concrete, and confirmed the salt deterioration resistance effect to use slag binder against to containing chlorides.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.455-464
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• 2020

Reinforcement corrosion is one of the major problems in the durability of reinforced concrete structures exposed to aggressive environments. Deterioration caused by reinforcement corrosion reduces the durability and the safety margin of concrete structures, causing excessive costs in managing these structures safely. This paper aims to investigate the effects of reinforcement corrosion on the load bearing capacity deterioration of the corroded reinforced concrete structures. A new analytical method is proposed to predict the crack growth of cover concrete and evaluate the residual strength of concrete structures with corroded reinforcement failing in bond. The structural performance indicators, such as concrete crack growth and flexural strength deterioration rate, are assumed to be a stochastic process for lifetime distribution modelling of structural performance deterioration over time during the life cycle. The Weibull life evolution model is employed for analysing lifetime reliability and estimating remaining useful life of the corroded concrete structures. The results for the worked example show that the proposed approach can provide a reliable method for lifetime performance assessment of the corroded reinforced concrete structures.