• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.397-405
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• 2001

In clod weather regions, a strong seasonal wind brings sea salts to the land. In addition to it, recently, the spreading amount of deicing salts has increased numerously for purpose of removing snow and ice. Thus the salts environment around concrete structures becomes so severe that various damages of concrete due to applied salts will be brought up. Much of countries such as America, Europe etc. is carried out study for effects of deicing salts on concrete. However, there are not test methods for deterioration of concrete subjected to both freezing-thawing and chloride in Korea. In this study, we carried out test for the compound deterioration subjected to both freezing-thawing and chloride attack, to investigate the effects of sodium chloride on the deterioration of concrete. The test was performed to investigate the effects of cement type, strength and air content on the scaling deterioration of concrete. As a result, the scaling deterioration was accelerated in the presence of salts. And the resistance to scaling was strongly influenced by the type of cement, the strength and air content of concrete.

• Resources Recycling
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• v.19 no.4
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• pp.35-40
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• 2010

Existing porous concrete has problems with reduction of strength due to freezing and thawing and exfoliation of aggregate at joints. In this study, a method for increasing strength and durability of porous concrete by using fine aggregate, silica-fume and high-range water-reducing agent was proposed by laboratory tests. Mixing ratio between silica-fume (10%) and fine aggregate (0%, 7%, 15%) was selected as a major test factor, and laboratory tests for compressive strength, flexural strength, permeability coefficient, porosity, freezing and thawing were conducted. Compressive strength and flexural strength were increased as the mixing ratio of fine aggregate was increased. However, permeability and freezing-thawing resistance were decreased due to reduction of porosity. Therefore, the ratio of fine aggregate should be limited to increase strength and durability of the porous concrete, while the mixing ratio of silica-fume should be over 10%.

• Korean Journal of Agricultural Science
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• v.30 no.2
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• pp.154-163
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• 2003

This study was performed to examine the freezing and thawing properties of the high strength concrete using recycled coarse aggregate. The recycled coarse aggregate was replaced by 0%, 25%, 50%, 75% and 100% of natural crushed aggregate. The compressive strength of the concrete used recycled coarse aggregate was shown in more than $400kgf/cm^2$ at the curing age 28 days. The weight loss ratio by freezing and thawing was shown in less than 1% at all mix type. The pulse velocity and relative dynamic modulus were decreased with increasing the freezing and thawing cycles. Also, durability factor for the freezing and thawing were decreased with increasing the content of recycled coarse aggregate. But, recycled concrete replaced with recycled coarse aggregate 100% was shown in more than 60 by durability factor in freezing and thawing of 300cycles Accordingly, these recycled coarse aggregate can be used for high strength concrete.

• Journal of the Korea Institute of Building Construction
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• v.12 no.3
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• pp.315-322
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• 2012

The effect of ground granulated blast-furnace slag(GGBS) and alkali activator compressive strength, resistance of chloride attack and freezing-thawing is assessed to develop high volume slag concrete, the replacement rate of GGBS of which is more than 80 percent. result, as the replacement rate of GGBS increases, the compressive strength development properties of concrete in early and long term age decreased and resistance chloride attack and freezing-thawing is increased. The early strength development property, however, is extremely advanced by addition of the alkali activator, which is also found to improve resistance chloride attack and freezing-thawing.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.457-460
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• 2008

CFRP plates has been established as an effective method for rehabilitation and strengthening of concrete structures. The CFRP reinforcements are bonded to beams and slabs using structural adhesives. Adhesive strength can be affected by environmental exposure. During freezing-and-thawing cycling, temperature-induced stresses in the adhesive layer, due to differential thermal expansion between the CFRP and the substrate concrete, may lead to bond damage and contribute to or cause premature CFRP composite separation. This paper presents the results of experimental program undertaken to investigate the effects of freeze-thaw cycling (from -18 to $4^{\circ}C$) on the behavior and failure characteristics of RC beams strengthened in shear with CFRP plate using acoustic emission (AE) technique.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.265-271
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• 2014

It is strongly needed to investigate the fine sand as an alternative fine aggregate of well-graded river sand because the fine sand which is being enormously distributed in the midstream and downstream of Nakdong-River in Korea has a poor grading but good quality as a fine aggregate for concrete. Thus, the purpose of this experimental research is to evaluate the durability of concrete using the fine sand to utilize it actively as a fine aggregate. For this purpose, the concrete specimens using different fine sand were made for the specified concrete strength of 35MPa, and then their durability such as the resistance to freezing and thawing and carbonation, and drying shrinkage were evaluated. It was observed from the test results that the resistance to freezing and thawing and carbonation of concrete using the fine sand was similar to that of concrete using reference sand, but the drying shrinkage of concrete using the fine sand with small fineness was comparatively lager than that of concrete using reference sand.

• Journal of Ceramic Processing Research
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• v.21 no.2
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• pp.164-169
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• 2020

This experimental study investigated the durability degradation of concrete exposed to freezing and thawing and chloride intrusion. In order to observe the degree of the degradation, 24 MPa, 35 MPa and 60 MPa concretes were used with 4% and 12% calcium chloride solution as freezing water for scaling resistance and freeze - thaw resistance tests. The results show that 24 MPa and 35 MPa concrete had a relatively large decrease in durability due to the freeze-thaw resistance and scaling resistance, but the 60 MPa concrete was not deteriorated significantly. In addition, when the concentration of the solution of calcium chloride was 4%, the degradation of durability was most remarkable. The results of this study suggest when concrete structures such as bridges or roads expose to the environmental conditions, appropriate measures such as increasing the designed standard strength of concrete need to be deliberated and additional studies should be conducted.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1097-1100
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• 2008

The purpose of this study to investigate the bond strength of recycled coarse aggregate concrete deteriorated by freezing and thawing. Concrete specimens with recycled coarse aggregate representing lower limit of the quality standard (water absorption : 3.0%, specific gravity : $2.5g.cm^3$) were manufactured and tested. The replacement ratio (0, 30, 60 and 100%) of recycled coarse aggregate and freezing-thawing cycles were considered in this test. From the test results, it was found that the bond strength of normal strength concrete is not affected by the replacement ratio of recycled coarse aggregate under freezing and thawing conditions. Also, the bond strength of the natural and recycled coarse aggregate concrete using AE admixtures was not decreased by frost action.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.9-17
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• 2010

This study aims to evaluate a porous concrete using hwang-toh, blast furnace slag and blast furnace slag (BFS) cement instead of type I cement. The tests that were carried out to analysis the properties of porous hwang-toh BFS cement concrete included compressive strength, continuous void ratio, absorption rate, and pH value, repeated freezing and thawing test were conducted. Test results indicated that the performance in porous hwang-toh concrete are effective on the kaoline based binder materials. The pH value were shown in about 9.5 ~ 8.5. The compressive strength was increased and void ratio was decreased with increasing the kaoline based binder materials, respectively. The void ratio and compressive strength were in the range of about 21 ~ 30 %, 8 ~ 13 MPa, respectively. The increased in void ratio of more than 25 % is showed to reduce the resistance of repeated freezing and thawing. Also, the resistance of repeated freezing of thawing and the compressive strength of porous hwang-toh BFS cement concrete are independent with hwang-toh content and BFS cement amount. But, the void ratio was decreased with increasing the high volume hwang-toh contents (more than 15 %).

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.589-592
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• 2008

This study was conducted to assess the durability of Chloride-inhibiting Low-Heat Cement while being subjected to freezing-thawing during winter seasons. Although durability varies slightly depending on the conditions of the jobsite, frost damage to concrete resulting from repeated freezing and thawing over the course of seasonal changes is the leading cause behind lowered concrete durability. in addition, concrete that has been subjected to freezing and thawing during the winter season develops a significant amount of expansive force at the core and begins to exhibit signs of damage, such as cracking, peeling, and detachment from the aggregate. Therefore, this study fabricated test specimens using a Chloride-inhibiting Low-Heat Cement(CLC) and the widely used blast furnace slag cement(BFS) and Ordinary Portland Cement(OPC) with water-to-cement ratios of 35%, 40% and 45%, respectively, to assess the durability index of the CLC as per resistance to freezing-thawing. The specimens were then tested using the KS F 2456 method (Testing method for resistance of concrete to rapid freezing and thawing) to measure the dynamic modulus of elasticity. The dynamic modulus of elasticity measurements were then used to derive the durability indices. By comparing the durability indices, it was confirmed that CLC, BFS, and OPC all had superior durability.