• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.253-254
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• 2009

This study was conducted to estimate deterioration reason of jointed concrete pavement. Image analysis tests were performed according to ASTM C 457 using concrete core specimens. Durability factors were estimated according to spacing factor, which is related with air content and air-void information. Test results show that spacing factors of most specimens were estimated above 250$\mu$m so that investigated concrete pavement has the problem of freeze and thawing resistance.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.475-482
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• 2007

The property and applicability of the organic-inorganic synthesized penetrating and reinforcing agent, which is developed in order to improve durability of concrete structures and prevent deterioration that may occur as service years increased, are researched with experimental works. TEOS (tetra-ethoxyorthosilicate) and acrylate monomer are synthesized by the solution polycondensation method in order to formulate silicate with sol-gel process and improve durability of concrete. Additional substances such as isobutyl-orthosilicate is supplemented in order to improve the performance of the agent. After the developed organic-inorganic penetrating reinforcing agent penetrates, a flexible impact alleviating layer is formed with organic monomers as well as the agent strengthens concrete by filling up the internal pore of concrete with stable compounds after penetration. Penetrating and reinforcing agent can be applied as an effective life management method because it makes concrete more durable against the aging factors, such as chloride ion, carbonation, freezing-thawing, and compound aging.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.114-122
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• 2016

Concrete is cost-benefit and high-durable construction material, however durability problem can be caused due to steel corrosion under chloride attack. Recently deicing salt has been widely spread in snowing season, which accelerates micro-cracks and scaling in surface concrete and the melted deicing salt causes corrosion in embedded steel. The previous governing equation of Fick's 2nd Law cannot evaluate the deteriorated surface concrete so that another technique is needed for the surface effect. This paper presents chloride penetration analysis technique for concrete subjected to deicing salt utilizing multi-layer diffusion model and time-dependent diffusion behavior. For the work, field investigation results of concrete pavement exposed deicing salt for 18 years are adopted. Through reverse analysis, deteriorated depth and increased diffusion coefficient in the depth are evaluated, which shows 12.5~15.0mm of deteriorated depth and increased diffusion coefficient by 2.0 times. The proposed technique can be effectively applied to concrete with two different diffusion coefficients considering enhanced or deteriorated surface conditions.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.26-32
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• 2012

Recently, concrete using multicomponent blended cement has been required to increase the freeze-thaw and sulfate resistances of concrete structures exposed to a marine environment. Thus, the purpose of this study was to propose the use of concrete containing multicomponent blended cement as one of the alternatives for concrete structures exposed to a marine environment. For this purpose, batches of concrete containing ordinary portland cement (OPC), binary blended cement (OPC-G, G: ground granulated blast slag), ternary blended cement (OPC-GF, F: fly ash), and quaternary blended cement (OPC-GFM, M: mata-kaolin) were made using a water-binder ratio of 50%. Then, the durability levels, including thesulfate and freeze-thaw resistances, were estimated for concrete samples containing OPC, OPC-G, OPC-GF, and OPC-GFM. It was observed from the tests that the durability levels of the concrete samples containing OPC-G and OPC-GF were found to be much better than that of the concrete containing OPC. The optimum mixing proportions were a40% replacement ratio of ground granulated blast slag for the binary blended cement and a30% replacement ratio of ground granulated blast slag and 10% fly ash for the ternary blended cement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.30-38
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• 2015

In cold-climate regions, deicing agents is used for smooth traffic on the road due to freezing and snowdrift in winter. The use of de-icing salts has resulted in the accelerated scaling damage of concrete with salt damage under freezing and thawing condition. Scaling is the deterioration of concrete where in the paste-mortar structure delaminates in flakes from the surface of the concrete. Due to such damage, concrete pavement causes various problems such as early deterioration according to the decrease in the thickness of cover concrete and user's stability issues. Accordingly, various tests and evaluation methods have been suggested in order to evaluate these phenomena in other countries. However, there have been no regulations for the evaluation method in South Korea, and related studies are also very rare. Therefore, in this study, the evaluation methods proposed by each institution and country were investigated and the experiments were performed according to each regulation, followed by the comparison and analysis of the results. Furthermore, this study aims to suggest the optimized experimental method adopted to domestic field through the discussion of such experimental methods and results.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.425-428
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• 2008

Concrete bridge decks, as well as asphalt pavement, are directly exposed to traffic loads and environmental conditions like rain water and deiceing chemicals. In this reason, there are often observed the deteriorations of asphalt overlay and of concrete deck under pavement. In this reason, it is important to identify the clear cause of concrete quality from a practical point of view. Therefore, in this paper it was initiated to ultimately suggest a protocol offering guidance as to assurance the quality control of concrete bridge deck on the part of void characteristics of concrete. Examinations such as visual inspection, deteriorated depth, and various void characteristic performed from cored specimens of 19 concrete bridge decks of various local conditions on the expressway. This paper discuss that the bridge deck condition analyses from the testing results were compared to a foreign guide line.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.149-150
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• 2020

Granting self-sensing performance in a building is an important performance to ensure the degree of damage and safety of the building. Since the current research is being conducted in the state before deterioration loss occurs, it is necessary to confirm whether the self-sensing performance is maintained even in the damaged conductive cement composite. As part of the study, electrical resistance characteristics were analyzed in conductive cement composites in which freeze-thawing and chemical corrosion occurred. As a result, it was found that the change in electrical resistance value due to freeze-thawing was not as large as 1%, and chemical corrosion occurred. It was found that the change in electrical resistance value of the tested specimen increased by about 10%.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.566-571
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• 2014

Recently, with concentrated social and engineering interests on durability, diversified subsequent researches have been progressed. The Chloride-induced corrosion, carbonation, freeze-thaw etc, deterioration factors of concrete act to concrete not privately but complexly, Fly ash is most frequently used admixture which is using a reduction method of deterioration. And the fly ash effects on improvement of durability with enhancement of fluidity, decrease of crack with reduction of hydration heat, promotion of long-age strength and have a economic advantage which replaces cement as a binding material. But, fly ash have different qualities and occasionally reduce the durability and strength by adhesion of AE admixture with unburned carbon powder etc. In this study, the experiments will take about various replacement ratio of fly ash concrete, and will analyze, consider the results, after these will verify applicability and validity as admixture and binding material.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.795-798
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• 1999

Deterioration induced by the freezing and thawing in concrete often leads to the reduction in concrete durability by the cracking or surface spalling. In this paper, the deterioration prediction model for concrete structures subjected to the irregular freeze-thaw was proposed from the results of accelerated laboratory test using the constant temperature condition and acceleration factor from the in-situ weather data.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.957-960
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• 2006

In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the Response Surface Method (RSM) is used. RSM has merits when the other probabilistic simulation techniques can not guarantee the convergence of probability of occurrence or when the others can not differentiate the derivative terms of limit state functions, which are composed of random design variables in the model of complex system or the system having higher reliability. For composing limit state function, the important parameters for cyclic freeze-thaw-deterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used as input parameters of RSM. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw for specimens show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages by the cyclic freeze-thaw by the use of proposed prediction method.