• International Journal of Highway Engineering
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• v.14 no.6
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• pp.25-35
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• 2012

PURPOSES : Hollows are easily made, and bearing capacity can be lowered near underground structures because sublayers of pavement settle for a long time due to difficult compaction at the position. If loadings are applied in this condition, distresses may occur in pavement and, as the result, its lifespan can decrease due to the stress larger than that expected in design phase. Although reinforced slab is installed on side of box culvert to minimize the distresses, length of the reinforced slab is fixed as 6m in Korea without any theoretical consideration. The purpose of this paper is investigating the behavior of concrete pavement according to the cover depth of the box culvert ad the length of the reinforced slab. METHODS : The distresses of concrete pavement slabs were investigated and cover depth was surveyed at position where the box culverts were located in expressways. The concrete pavements including the box culverts were modeled by finite element method and their behaviors according to the soil cover depth were analyzed. Wheel loading was applied after considering self weight of the pavement and temperature gradient of the concrete pavement slab at Yeojoo, Gyeonggi where a test road was located. After installing pavement joint at various positions, behavior of the pavement was analyzed by changing the soil cover depth and length of the reinforced slab. RESULTS : As the result, the tensile stress developed in the pavement slab according to the joint position, cover depth, and reinforced slab length was figured out. CONCLUSIONS : More reasonable and economic design of the concrete pavement including the box culvert is expected by the research results.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.139-148
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• 1993

Thermosyphons are simple devices that can passively transport thermal energy over relatively long distance with little temperature degradation. These attributes permit the use of low grade thermal energy for thermal control of structures including the snow melting and deicing to the pavement surface. The thermosyphon system requires no costly energy input and Is completely maintenance free. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to transfer the geothermal energy to the pavement to obviate slipping traffic accidents due to freezing of pavement in winter.

• International Journal of Contents
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• v.6 no.4
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• pp.39-42
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• 2010

In this paper we developed density measurement equipment for Asphalt Pavement based on the electromagnetic capacitance. This kind of Non-Nuclear Density Gauges technology and products is used or studied in USA, Finland, Sweden as standardization of authorized method for pavement density measurement. Effective permitivity of pavement asphalt is characterized in electromagnetic capacitance by the asphalt material, mixed ratio, and harden grade of pavement asphalt. We can get a density value of asphalt by replacing value of electromagnetic capacitance with standard density value and characteristic transformation curve. We are conformed that measurement data according to temperature, humidity, and real field asphalt of our density measurement equipment can be a precise value.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.55-62
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• 2015

Cracking is an inevitable fact of asphalt concrete pavements and plays a major role in pavement deterioration. Pavement cracking is one of the main factors determining the frequency and method of repair. Cracks can be treated with a number of preventative maintenance actions, including overlay surface treatments such as slurry sealing, crack sealing, or crack filling. Pavement cracks can show up as one or all of the following types: transverse, longitudinal, fatigue, block, reflective, edge, and slippage. Crack sealing is a frequently used pavement maintenance treatment because it significantly extends the pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Because current test methods are mostly empirical and only provide a qualitative measure of the bond strength, they cannot accurately predict the adhesive failure of the sealant. This study introduces a laboratory test aimed at assessing the bonding of hot-poured crack sealant to the walls of pavement cracks. A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the bonding strength of the hot-poured crack sealant as a function of the curing time and temperature. Based on a limited number of test results, the hot-poured crack sealants have very different bonding performances. Therefore, this test method can be proposed as part of a newly developed performance-based standard specification for hot-poured crack sealants for use in the future. PURPOSES : The purpose of this study was to evaluate both the adhesion and failure performance of a crack sealant as a function of its curing time and curing temperature. METHODS: A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the adhesion performance of a crack sealant as a function of the curing time and curing temperature. RESULTS: With changes in the curing time, curing temperature, and sealant type, the bond strengths were found to be significantly different. Also, higher bond strengths were measured at lower temperatures. Different sealant types produced completely different bond strengths and failure behaviors. CONCLUSIONS: The bonding strength of an evaluated crack sealant was shown to differ depending on various factors. Two sealant types, which were composed of different raw materials, were shown to perform differently. The newly proposed test offers the possibility of evaluating and differentiating between different crack sealants. Based on alimited number of test results, this test method can be proposed as part of a newly developed performance-based standard specification for crack sealants or as part of a guideline for the selection of hot-poured crack sealant in the future.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.95-104
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• 2014

PURPOSES : The purpose of this study is to evaluate the degree of restraint (DOR) of longitudinal steel at continuously reinforced concrete pavement (CRCP) against environmental loadings. METHODS : To measure the longitudinal steel strain, 3-electrical resistance and self-temperature compensation gauges were installed to CRCP test section (thickness = 250mm, steel ratio = 0.7%) and continuously measured 10 min. intervals during 259 days. In order to properly analyze the steel strains first, temperature compensation process has been conducted. Secondly, measured steel strains were divided into 12 phases with different events such as before paving, during concrete hardening, and after first cracking, etc. RESULTS : Thermal strain rate (TSR) concept is defined as the linear strain variations with temperature changes and restraints rate of longitudinal steel against environmental loadings (especially thermal loading) with different cases is defined as degree of restraint(DOR). New concept of DOR could be indirect indicator of crack width behaviors of CRCP. CONCLUSIONS : Before paving, DOR of longitudinal steel is almost same at the coefficient of thermal expansion of steel ($12.44m/m/^{\circ}C$) because of no restraint boundary condition. After concrete pouring, DOR is gradually changed into -1 due to concrete stiffness developing with hydration. After first cracking at crack induced area, values of DOR are around -3~-5. The negative DOR stands for the crack width behavior instead of steel strain behavior. During winter season, DOR reached to -5.77 as the highest, but spring this values gradually reduced as -1.7 as the lowest. Based on this observation, we can presume crack width decreased over time within the time frame of this study. This finding is not consistent with the current theory on crack width variations over time, so further study is necessary to identify the causes of crack width reducing. One of the reasons could be related to concrete stress re-distribution and stress relaxation.

• Journal of Environmental Policy
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• v.10 no.1
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• pp.27-47
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• 2011

Used as foundation resources for environment improvement and preservation of single-housing residential area by practicing classification of biotope with the concept of ecological area rate applied and performing urban thermal environment prediction simulation. Biotope is classified as seven types according to classification of biotope which is carried out with the concept of ecological area rate applied. The classification is listed below in descending order: building biotope(48.16%), impervious pavement biotope(39.75%), greenspace biotope(6.23%), crack permeable pavement biotope(3.26%), whole surface permeable pavement biotope(2.51%), parts permeable pavement biotope(0.04%). As a result of analysing prediction of variation and characteristics of thermal environment of single-housing residential area, land surface temperature per types of biotope are evaluated as listed below in descending temperature order: impervious pavement biotope > building biotope > greenspace biotope > permeable pavement biotope. In case 2 where vegetated roof hypothetically covers 100% of the roof area, temperature is predicted to be $33.58^{\circ}C$ Max, $23.85^{\circ}C$ Min, and $27.74^{\circ}C$ Avg. which is Approximately $5.19^{\circ}C$ lower than a non-vegetated roof. Average outdoor temperature for case 2 is studied to be $0.18^{\circ}C$ lower than case 1.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1E
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• pp.3-6
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• 2001

Sound pressure level (SPL) measurements were performed on a controlled test track vehicle coast-by runs of a passenger vehicle with six different sets of tires across a range of temperatures. A small but significant reduction of noise level with positive temperature increases was observed for some tires. The temperature gradient of the different tires at 80㎞/h ranged from -0.07 to + 0.01 dB/℃. Frequency analysis of the tire noise identified that noise content in the range of 1,300 to 1,900Hz was particularly sensitive to temperature changes. Differences in SPL due to speed and tire type were much greater than that due to temperature.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.576-580
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• 2000

Tire-pavement noise is a significant portion of noise coming from road vehicles and is therefore a logical focus of efforts to reduce overall traffic noise. A small but significant reduction of noise level with positive temperature increases was observed for some tires. The reduction was evident in two of the tires at 53 km/h and five of the tires at 80 km/h. The temperature gradient of the different tires at 80 km/h range from -0.07 to +0.01 dB/$^{\circ}C$. Frequency analysis of the tire noise identified that noise content in the range of 1,300 to 1,900 Hz is particularly sensitive to temperature changes.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.663-668
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• 1997

In Korea, the temperature of winter seasons are really severe and cause lot's of snow-falling and iceing in the pavements. Several de-iceing mehtod have generally been adopted to melt the ice on the surface of pavement. Therefore, the Study of experimental in the first stage was given to the verification of the icers's effects. First, Contrete and asphalt pavement specimens were made and scattered with a CaC2-deicers. then 3cm and 5cm thickness of artificial snow were prepared on the surface of specimens. It reveals that the early calorification due to de- icers as high as the temperature of laboratory increases within about 10 minutes and last for more then 2 hours and the test of ice-formation on the surface of contrete and asphalt specimen due to snow leads to the similar rate of freezing time about 20 minutes. Second, three kinds of de-icers, such as CaC2 CaC2+Nacl, Cacl Flaket are rested in the snowy highway to check the iceing-resistance. The CaC2 is proved to be the most effective de-icers so far.

• Journal of the Society of Disaster Information
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• v.9 no.1
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• pp.56-64
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• 2013

The study examines the quiet pavement using fine-size aggregates and warm-mix technique to reduce traffic noise. In order to evaluate the quality of pavement, mix design and laboratory tests were carried out. Test results showed that using 10mm aggregates can reduce the cantabro loss compared with 13mm aggregates due to increase contact area between aggregates. Mixing and compaction temperatures of warm mix quiet pavement should be determined by gyratory compactor test because it is used high viscosity asphalt binder. Using warm-mix additive could reduce compaction temperature by about $15^{\circ}C$. Noise measurement and permeability tests were conducted at the test road for evaluation of the field performance. All of quiet pavements meet the standard of permeability and have sufficient porosity. Noise reduction of the quiet pavement using fine-size aggregates is more effective than that using 13mm aggregates. In particular, the effect of noise reduction was noticeable at low speeds.