• International Journal of Highway Engineering
• /
• v.9 no.4
• /
• pp.149-158
• /
• 2007

Evaluation of the asphalt mixture modified with crumb rubber modifier(CRM) was performed to estimate possibility of using it as a paying material. OACs(optimum asphalt content) of CRM modified asphalt mixtures by dry process and wet process were determined by Marshall mix design and Wheel tracking test and moisture susceptibility test by freezing and thawing were carried out with CRM modified asphalt mixtures at OACs. The results from these tests, resistance of permanent deformation of CRM modified asphalt mixtures were superior to one of AP-5 while showing very low resistance of moisture sensitivity by freezing and thawing. This means that CRM modified asphalt mixtures are very sensitive to freezing and thawing. However, CRM modified asphalt mixture with anti-stripping material showed high improvement to resistance of moisture susceptibility by freezing and thawing. Therefore, it is recommended that when CRM mixtures were used in domestic, CRM modified asphalt mixtures should be with prevention against freezing and thawing resistance by moisture susceptibility.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.3 no.4
• /
• pp.355-365
• /
• 2015

This study examined the fluidity and strength properties, water resistance, durability, and freeze-thaw of cementless loess mortar using an eco-friendly hardening agent. The experimental result indicates that 28 days compressive and flexural strength of the loess mortar was increased regardless of the weathered granite soil and loess mixture ratio as the replacement ratio of the hardening agent increases. The strengths were significantly increased until 14 days regardless of the hardening agent, while the effect on the strengths increasement was relatively low after 14 days. Thus, the strength development of loess mortar concrete was found to be faster than that of the normal concrete. In addition, when the hardening agent of 10% was used, the average flexural strength was 1.7MPa which is insufficient compared to the 28-day flexural strength of 4.5MPa for the paving concrete. However, the flexural strengths of the loess mortar concrete using the hardening agents of 20% and 30% were 4.0MPa and 5.3MPa, respectively. Thus, the hardening agent need to be at least 20% so that the loess mortar can be used for paving concrete. The experiment for water resistance shows that the repeated absorption and dry reduced mass regardless of the mixing ratio of the loess. The maximum length change also decreased with increasing the substitution rate loess mixture ratio and the hardening agent. The result of the freeze-thaw resistance test indicates that the relative dynamic modulus of elasticity at 300 cycle freeze-thaw with the hardening agents of 20% and 30% were 75% and 79%, relatively. Thus, the hardening agent of at least 20% is required to obtain the relative dynamic modulus of elasticity of 60% for the loess mortar.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.287-288
• /
• 2010

The purpose of this study aimed to evaluate properties of water resistance, disease of freezing and thawing and XRF of Loess mortar using non-cement binder to solve reduction of durability by freezing and thawing on exiting Loess bicycle load.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.11a
• /
• pp.190-191
• /
• 2014

The building insulation materials shall keep their thermal conductivity constant even when the freezing and thawing repeats for over a long time. But, in this condition of repeated freezing and thawing, the organic building insulation material may suffer the degradation in the thermal performance as the gas put into the insulation materials gets out slowly over a long time. Accordingly, in this study, the change in the thermal performance has been tested and evaluated when the repeated freezing and thawing cycles happen.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.41 no.3
• /
• pp.66-72
• /
• 1999

The purpose of this experiment is to estimate freezing and thawing resistance of rice straw ash concrete. Test results show that mass, pulse velocity and relative synamic modulus of elasticity are gradually decreased with increase of freezing and thawing cycle. The durability factor(DF) is in the range of 85.48 ∼86.33 in the rice straw ash comcrete with 2.5% , 5% 7.5%, rice straw ash and higher than that of thenormal cement concrete. But, DF of 10% , 12.5%, 15% rice straw ash filled rice straw ash concrete is in the range of 41.26∼65.34 and lower than that of the normal cement concrete.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.6 s.58
• /
• pp.115-125
• /
• 2009

In these days, carbon fiber-reinforced polymers (CFRP) have been widely used for retrofitting and/or strengthening structural elements. However, there are not enough test data to predict the long-term performance of the retrofitted structures exposed to freeze-thawing cycles. This paper presents the results of experimental program undertaken to investigate the effects of freeze-thawing cycling (from-18 to $4^{\circ}C) on the behavior and failure characteristics of reinforced concrete (RC) beams strengthened in shear with CFRP sheet and plate using acoustic emission (AE) technique.

• Journal of the Society of Disaster Information
• /
• v.9 no.4
• /
• pp.469-475
• /
• 2013

The purpose of this experimental research is to estimate compressive strength and resistance to freezing and thawing of recycled aggregate concrete containing ground granulated blast furnace slag. For this purpose, concrete specimens according to substitution ratio of recycled aggregate were made for different replacement ratio of ground granulated blast furnace slag(GGBFS), and then compressive strength and resistance to freezing and thawing were evaluated for those. It was observed from the test results that compressive strength at 28 days of recycled aggregate concrete containing GGBFS of 20% was much more excellent than plain concrete and when air content of concrete was maintained 4 to 6%, influence of substitution ratio of recycled aggregate and replacement ratio of GGBFS on resistance to freezing and thawing was little up to 300 cycles of freezing and thawing.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.4
• /
• pp.149-156
• /
• 1995

The fracture process zone in concrete is a region ahead of a traction-free crack, in which two major mechanisms, microcracking and bridging, play important roles. The toughness due to bridging is dominant compared to toughness induced by microcracking, so that the bridging is dominani: mechanism governing the fracture process of concrete. Fracture mechanics does work for concrete provided that the fracture process zone is being considered, so that the development of model for the fracture process zone is most important to describe fracture phenomena in concrete. In this paper the bridging zone, which is a part of extended rnacrocrack with stresses transmitted by aggregates in concrete, is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve. Two finite element techniques are shown for the analysis of progressive cracking in concrete based on the discrete crack approach: one with crack element, the other without crack element. The advantage of the technique with crack element is that it dees not need to update the mesh topology to follow the progressive cracking. Numerical results by the techniques are demonstrated.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.1 no.3
• /
• pp.173-180
• /
• 2013

This paper is to investigate an effect of waste cooking oil(WCO) on the engineering properties and durability of high volume admixture concrete. Fly ash with 30% and blast furnace slag with 60% were incorporated in OPC to fabricate high volume admixture concrete with 0.5 of W/B. Emulsified refining cooking oil(ERCO) was made by mixing WCO and emulsifying agent to improve fluidity. ERCO was replaced by cement from 0.25 to 1.0%. As results, the increase of ERCO resulted in decrease of slump and air contents. For compressive strength, the use of ERCO led to decrease the compressive strength at 28 days, while it had similar strength or much higher strength than plain concrete at 180 days. Resistance to carbonation and chloride penetration was improved with the increase of ERCO contents due to decreased pore distribution by saponification between ERCO and concrete, while freeze-thaw resistance was degraded due to air loss.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.4
• /
• pp.128-135
• /
• 2016

In the current concrete structure of the highway is still the major problem most of concrete deterioration caused by the freeze-thaw and deicing salt, which is of issues that are not completely resolved. In particular, a single freezing event does not cause much harm, durability of concrete under multi-deterioration environment by repeated freeze-thaw and deicing salt is rapidly degraded and reduce its service life. In this study, the exposure environmental condition according the regional highway points were established. The damage condition and chloride content of the concrete at general and severe environmental exposure condition were also investigated. In addition, the experimental test of chloride ion permeability, scaling resistant and freeze-thaw resistance were carried out to improve the durability of the mechanical placing concrete of subsidiary structure. According to the results of this study, in observation of concrete surface condition, the concrete exposed by severe environmental condition showed broad ranges of damage with high chloride contents. Meanwhile, the water-binder(W/B) ratio and the less water content, and fly ash concrete than the specified existing mix proportion is significantly improved the durability. Also, the optimal mix proportion derived for test is satisfied the strength and air contents, water-binder ratio, and durability criteria of concrete specifications, as well as service life seems greatly improved.