PURPOSES : The actual service life of repair methods applied to cement concrete pavement is analyzed based on de-icing agent usage. METHODS : Highway PMS data pertaining to de-icing agent usage are classified into three grades: low (1~5 ton/lane/year), medium (5~8 ton/lane/year), and high (greater than 8 ton/lane/year). The repair methods considered include diamond grinding, patching, joint repair, partial depth repair, and asphalt overlay on five major highways. The service life of each repair method is analyzed based on the usage level of the de-icing agent. RESULTS : The service lives of the applied repair methods are much shorter than expected. It is confirmed that the service life afforded by diamond grinding, patching, and joint repair methods are not significantly affected by the use of de-icing agents, whereas that afforded by asphalt overlay and partial depth repair methods is affected significantly. The service life afforded by the asphalt overlay and partial depth repair methods decreases at high usage levels of the de-icing agent (greater than 8 ton/lane/year). CONCLUSIONS : Among the repair methods considered, the service life afforded by partial depth repair and asphalt overlay is affected significantly by the amount of de-icing agent used. Additionally, the differences between the expected and actual analyzed service lives should be considered in the next-generation maintenance strategy for cement concrete pavements.

PURPOSES: The intensiveness of highway management has increased owing to the growth in the number of vehicles and the rapid climate change. The disadvantages produced by these factors can affect management time and cost. Serious traffic accidents and traffic jam may be experienced when snow fall accumulates on highway surfaces and the friction between tires and pavements is lower than that in the general state, in a non-management condition. Such conditions need intensive management. In this regard, one of the spread methods used for the melting material is pre-wetted salt (PWS), which is the frequently used method in South Korea. In the PWS method, the solid material with CaCl2 is mixed with water in 30% concentration and then finally mixed with NaCl before application to pavements. The chloride-type melting material not only is cheaper, but also has a high melting property than the others. It can shorten the pavement or structure life by deterioration and corrosion. This melting material can affect the flora near the highways; hence, an eco-friendly de-icing agent must be utilized considering the environmental effect. METHODS : The Kalman filter algorithm (KFA) was utilized herein to develop optimization models using the performed test data. The KFA, which was developed from recursive filter algorithms, such as the low- and high-pass filters, applies a weighting filter to the Kalman filter. The algorithm has the property of utilizing the filter and updated estimations. In this regard, melting tests were performed for the real applicative utilization of de-icing agents. The KFA was also applied to reduce the error rates and optimize the relationships between the test data and the predictions. RESULTS: Comparing the measurements performed, the error was reduced by 1.69 g when the KFA was applied. Moreover, the error can be optimized to approximately 91.4% compared to the test errors. The prediction data had over 85% tendency in the test measurement, showing that the KFA application can reduce the error and increase the tendency. By comparison, the agent with CaCl2 showed the best ice melting performance within 10 min without surface temperature. However, the PWS with a 25% concentration indicated the best water melting performance from start to end of the test time, implying that this is a powerful agent in terms of performance. CONCLUSIONS : The melting test is an artificial test method; therefore, it can generate a huge error from the test. The error and the tendency can be controlled by tracking the measurement error and the white noise matrix using the KFA. A further research will be performed to track the measurement error and the white noise matrix. Other optimization methods will also be applied to reduce the experimental error.

An icing phenomenon of wind turbine blade are caused by wind speed, air temperature, liquid water content, droplet size, and so on. In this study, the analyses were carried out at a liquid water content of 0.20g/㎥, droplet size of 25 um, wind speed of 11.4m/s and air temperatures of -15, -10, -5℃ using NREL 5MW wind turbine. The software uses FENSAP-ICE's CFD Flow Solver, Drop 3D and ICE 3D. The analysis of icing shape and mass with temperatures according to air foil was derived, and the required heat quantity for de-icing was calculated at NACA 64618 airfoil for air temperature of -15℃. Power curves with wind velocities are suggested for economical analysis.

PURPOSES :This study evaluates the reasonableness of the recommended amount of deicing chemicals based on historical data for snow removal. The result can be used to aid decision-making for the reservation of cost-effective de-icing chemicals.METHODS :First, the recommended amount of de-icing chemical to use and historical usage data were evaluated to identify specific usage characteristics for each region. Road maintenance length and snow-removal working days were analyzed over the past five winter seasons. Next, differences in the recommended amount of chemical to use and actual use were compared using the Kolmogorov-Smirnov test. Last, the two types of data were analyzed using a chi-square test to verify if the two distributions of variation pattern are statistically significant. We found that there are significant differences between the data from each region during the past five winter seasons.RESULTS :The results showed that the equation for calculating the amount of de-icing chemical to use appears to be revised.CONCLUSIONS :The results imply that the equation for calculating the amount of de-icing chemical to apply as a national standard is very important when the public agency makes decisions related to snow-removal.

PURPOSES: The purpose of this study is to analyze the service life of expressway pavement based on both traffic volumes and use of deicing chemicals. METHODS: A database was built using expressway rehabilitation history information from over the last decade. In order to estimate the service life of expressway pavement, various analysis methods were considered, and a decision was made to perform analysis using a method based on an accumulated rehabilitation ratio. The service life of expressway pavement was then analyzed by classifying the scale of traffic volume and extent of de-icing chemicals used. RESULTS: The service life of PMA and SMA ranged from 7.8 to 10.6 years and from 9.9 to 12.0 years, respectively. The service life of JCP ranged from 16.0 to 22.2 years, and the service life of CRCP was 33.5 years on average. Results of assessing service life according to traffic volumes and de-icing chemicals showed that the lower the traffic volumes were, the greater the service life of PMA and JCP, and the less that de-icing chemicals were applied, the greater the service life of JCP. CONCLUSIONS : The dependence of expressway pavement service life on traffic volumes and de-icing chemicals makes it possible to apply LCCA for regional maintenance plans and cost-effective selection of expressway pavement type.

This study was conducted to investigate the growth of Dendranthema zawadskii in damaged soils when they are treated with improvement agents. The treatments consisted of a control (unamended field soil) and the application of a loess ball of 1 cm to the field soil. According to the degree of damage the de-icing agent had caused, the soils were divided into 3 areas (based on the yellowing of Pinus densiflora for. multicaulis in soil surveys): H (high saline), M (medium saline), and L (low saline). A total of six treatments were performed: D. zawadskiia plant without soil amendment (H; high saline soil, M; medium saline soil, L; low saline soil), and a D. zawadskiia plant with loess ball on the soil surface (H.L; high saline soil with loess ball, M.L; medium saline soil with loess ball, L.L; low saline soil with loess ball). The results showed that D. zawadskiia growth went from highest to lowest in the order: M.L > L.L > M > L > H.L > H. Plant growth results showed that soils treated with soil amendments (loess ball) were better for D. zawadskii growth than untreated soils.

This study was conducted to analyze seasonal variations of de-icing salt ions harvested from soils and plants according to salt damage of Pinus densiflora f. multicaulis, a evergreen conifer, on roadsides. Pinus densiflora f. multicaulis was divided into three groups referred to SD, ND, and WD (serious salt damage (SD) = 71 100%, normal salt damage (ND) = 31 70%, and weak salt damage (WD) = 0 30%) based on the degree of visible foliage damage, and measured acidity (pH), electrical conductivity(EC), and de-icing salt ions (K+, Ca2+, Na+, and Mg2+) harvested from soils and plants. The results indicated that acidity, electrical conductivity, and de-icing salt ions of soils and plants were significantly affected by seasonal variation and salt damage. In addition, a strong positive liner relationship was observed in plants between the concentration of de-icing salts and salt damage in spring, while the relationship among seasonal variation and salt damage in soil were not significant. The results from this study has important implications for the management of conifer species in relation to salinity and roadsides maintenance.

De-icing work in highways has been changed from sand and calcium chlorides spreading to pre-wetted salt spreading since 2000s. Recently, the concern on the premature deterioration of concrete structures due to de-icing salts and its counter measurements has been increased. This paper describes the change of de-icing methods and deterioration due to chloride attack and specification of durable concrete.

The purpose of this study is to prevent the occurrence of safety accidents and traffic accidents in winter by presenting the criteria of de-icing and anti-icing of cable-supported marine bridges. In winter, due to the structural characteristics of the cable support bridge, the main tower and the cable are positioned upon the reinforcing beam that the vehicle passes through, and snow and ice that piled on the main tower and the cables is fall to the road. so It can be a reason of the traffic accident. In this study, we analyzed the mechanism for the snow accretion and ice accretion and suggested preventive measures about de-icing and anti-icing.

A huge amount of de-icing agent is sprayed during winter to promote traffic safety in cold regions, and the quantity of de-icing agent sprayed has increased each year. The main ingredients in commonly used de-icing agents are chlorides, such as calcium chloride(CaCl2) and sodium chloride(NaCl). While calcium chloride is mostly used in Korea and sodium chloride is usually used in the U.S. and Japan, all de-icing agents include chloride ions. The chlorides included in sprayed calcium chloride-based de-icing agents have severe adverse effects, including the corrosion of reinforcing steels through salt damage by infiltrating into road structures, reduced structural performance of pavement or damage to bridge structures, and surface scaling, in combination with freezing damage in winter, as well as water pollution. In addition, the deterioration of paved concrete road surface that occurs after the use of calcium chloride-based de-icing agent accelerates the development of visual problems with traffic structures. Therefore, the present study was performed to prepare an environment-friendly liquid de-icing agent through a reaction between waste organic acids and calcium-based by-products, which are industrial by-products, and to analyze the properties of the de-icing agent in order to evaluate its applicability to road facilities.

The airborne chlorides environment by de-icing salts of the Suam road tunnel in motorway were examined. It was found that higher airborne chlorides were detected inside road tunnel than outside. Therefore, there is a need to appreciate that RC structures inside tunnel might be exposed to salt attack environment.

The airborne chlorides environment by de-icing salts of the Suam road tunnel in motorway were examined. It was found that higher airborne chlorides were detected inside road tunnel than outside. Therefore, there is a need to appreciate that RC structures inside tunnel might be exposed to salt attack environment

The maintenance costs will be increased due to the aging of the bridge. Most of maintenance activity is generally known for preventing and repairing the deterioration by de-icing salts. The objective of this research is to investigate the minimizing strategy of maintenance costs for the deterioration by de-icing slats of highway bridges.

Recently, the concern on the deterioration of concrete due to de-icing salts and its counter measurements has been increased. This paper discusses the durability Assessment procedure of RC Structures against chloride attack under depicing salt environments.

In the past, concrete pavements were routinely designed and constructed to provide low-maintenance service lives of 20 to 25 years. More recently, there has been a movement toward construction of pavements with a longer initial service life of 40 or more years. This paper discusses a mixture improvement for long life concrete pavement.

Maintenance costs, depending on the occurrence of deterioration expressway bridges has been increasing at a very rapid rate (approximately 200% increase in the last five years). In order to reduce the damage caused by water leakage and de-icing salt damage, We proposed a design improvement of concrete slab edge.

Maintenance costs, depending on the occurrence of deterioration expressway bridges has been increasing at a very rapid rate (approximately 200% increase in the last five years). In order to reduce the damage caused by water leakage and de-icing salt damage, We proposed a design improvement of concrete slab edge.

In order to estimate the influence of chloride de-icing materials which mainly cause the corrosion of steel structures, the salt spray test was conducted and the corrosion level of steel was investigated. The concentration of the chloride de-icing materials and the number of the spray were selected as variables, and the influence of chloride de-icing materials was estimated according to weight reduction of steel specimens.

The airborne chlorides environment by de-icing salts of retaioning wall in motorway were examined. It was found that in the retaining wall, height of 14m, the airborne chlorides tend to be decreased by height ranged between 81.0-73.8%.

Recently, the concern on the deterioration of concrete due to de-icing salts and its counter measurements has been increased. This paper discusses the results from investigation of pre-mature deteriorated existing road-subsidiary concrete structures and the specification of concrete quality.