• International Journal of Highway Engineering
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• v.14 no.4
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• pp.1-8
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• 2012

PURPOSES : Skid resistance on pavements plays an important role in reducing the risk of vehicle skidding on wet surface particularly. Almost 9.3 percent of traffic accidents were occurred under rainy condition and these are over-represented in terms of the severity of the crashes. Recently, unusual weather conditions referred widely as the intensified rainfalls justify the need of a systematic management of skid resistance. In this context, the study carried out the observational study on the skid resistance characteristics of different types of pavement with the time passage. METHODS : This study measured the skid resistance with Pavement Friction Tester at three times within five years. The skid resistance measurement has followed the method suggested by ASTM. RESULTS : As the main results under the scope of this study, skid resistance of asphalt concrete has not nearly reduced with time. On the contrary, skid resistance of cement concrete has been rapidly reduced with time though the highest resistance was gained at the early observation. Porous asphalt concrete shows a steady decrease of skid resistance with time, anyway, the reduction rate according to the increase of measurement speeds is relatively lower than the others. CONCLUSIONS : Based on our study, skid resistance of the pavement should be regarded as one of the pavement management system, so periodic measurement should be made to assure road safety as a whole.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.6
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• pp.26-37
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• 2008

The purpose of the study was to evaluate the effect of pervious pavements on reducing the surface runoff caused by rainfall. The surface runoff from twelve steel experimental beds with different pavement had been recorded every minute from May to September 2008, by the measuring system of tipping buckets(0.1mm/count) and data aquisition systems(National Instrument's Labview and DAQ boards & Autonics PR12-4). The dimension of the experimental bed was $1.5m(W){\times}2.0m(L){\times}0.6m(D)$ and eleven different kinds of vegetational(grass, grass+cubic stone, grass+hole brick), modular(brick, cubic stone, small cubic stone, wood block, interlocking block, clay brick, granular clay brick) and granular(naked soil, gravel) paving materials and concrete were applied for the comparison. Six rain events with depth over 30mm were selected and compared. The maximum depth of the rainfall selected was 137.5mm for 28 hours, and the minimum 30mm for 5 hours. The maximum rainfall per hour was 23mm/hr and the minimum 11.4mm/hr. The major findings were as follows; 1. All pervious pavement applied reduced over 75% of the surface runoff compared with concrete pavement. The grassy and porous pavements were relatively efficient in reducing surface runoff. 2. The grass was the more efficient as intercepting average 69.5mm of initial surface runoff, and maximum 77.8mm at the condition of 13.5mm/hr rainfall. The next was gravel intercepting maximum 65.5mm at the condition of 13.5mm/hr and the 40.9mm at 19.1mm/hr, average 55.7mm. 3. The modular pavements common in urban area were not good in intercepting the runoff except the 'clay granular brick' compared with others. The 'clay granular brick' showed relatively efficient intercepting average 14.1mm, which was the bigger amount than the 'grass+hole brick'. 4. The 'naked soil' were more effective than the 'concrete', 'brick', and 'interlocking block' in reducing the surface runoff, but less efficient than other materials. The capacity of the 'naked soil' to intercept the initial rainfall was similar to the 'brick'. As summary, the more grassy and porous pavement shows more effective in reducing surface runoffs.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.45-52
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• 2013

PURPOSES : This study is to construct the regression models of drainage asphalt concrete specimens and to provide the appropriate coefficients of hydraulic conductivity prediction models. METHODS: In terms of easy calculation of the hydraulic conductivity from porosity of asphalt concrete pavement, the estimation model of hydraulic conductivity was proposed using regression analysis. 10 specimens of drainage asphalt concrete pavement were made for measurement of the hydraulic conductivity. Hydraulic conductivity model proposed in this study was calculated by empirical model based on porosity and the grain size. In this study, it shows the compared results from permeability measured test and empirical equation, and the suitability of proposed model, using regression analysis. RESULTS: As the result of the regression analysis, the hydraulic conductivity calculated from the proposal model was similar to that resulted from permeability measured test. Also result of RMSE (Root Mean Square Error) analysis, a proposed regression model is resulted in more accurate model. CONCLUSIONS: The proposed model can be used in case of estimating the hydraulic conductivity at drainage asphalt concrete pavements in fields.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.2
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• pp.157-166
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• 2012

Most of the roads are paved with impermeable materials such as asphalt concrete and cement concrete, and in the event of heavy rainfall, rainwater directly flows into river through a drainage hole on the pavement surface. This large quantity of rainwater directly spilled into the river frequently leads to the flooding of urban streams, damaging lowlands and the lower reaches of a river. In recent years there has been a great deal of ongoing research concerning water permeability and drainage in pavements. Accordingly, in this research, a porous polymer concrete was developed for permeable pavement by using unsaturated polyester resin as a binder, recycled aggregate as coarse aggregate, fly ash and blast furnace slag as filler, and its physical and mechanical properties were investigated. Also, 3 types of permeable polymer block by optimum mix design were developed and rainfall runoff reduction effects by permeability pavement using permeable polymer block were analyzed based on hydraulic experimental model. The infiltration volume, infiltration ratio, runoff initial time and runoff volume in permeability pavement with permeable polymer block of $300{\times}300{\times}80$ mm were evaluated for 50, 100 and 200mm/hr rainfall intensity.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.2
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• pp.1-8
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• 2010

The purpose of the study was to evaluate the influence of landscaping pavements on WBGT(Wet-Bulb Globe Temperature) of outdoor spaces that lack ventilation and shade at summer midday. The relative humidity(RH), dry-bulb temperature(DT) and globe temperature(GT) were recorded every minute from June to October 2009 at a height of 1.2m above ten experimental beds with different pavements, by a measuring system consisting of an electric humidity sensor(GHM-15), resistance temperature detector(RTD, Pt-100), standard black globe(${\phi} 150mm$) and data acquisition systems(National Instrument's Labview and Compact FieldPoint). Additionally, the surface dry-bulb temperatures also were recorded and compared. The area of each experimental bed was 1.5m(W)${\times}$2.0m(L) and ten different kinds of pavement were used including grass, grass+cubic stone, grass+porous brick, brick, stone panels, cubic stone, interlocking blocks, clay brick, naked soil, gravel and concrete. To prevent interference from ventilation, a 1.5m height cubic steel frame was established around each bed and each vertical side of the frame was covered with transparent polyethylene film. Based on the records of the hottest period from noon to 3 PM on 26 days with a peak dry-bulb temperature over $30^{\circ}C$ at natural condition, the wet-bulb temperature(WT) and WBGT were calculated and compared. The major findings were as follows: 1. The average surface DT was $40.1^{\circ}C$, which is $9^{\circ}C$ higher than that of the natural condition. The surface DT of the pavements with grass were higher than those of concrete and interlocking block. The peak DT of the surface almost every pavement rose to above $50^{\circ}C$ during the hottest time. 2. The averages of DT, WT and GT were $40.1^{\circ}C$, $27.5^{\circ}C$ and $49.1^{\circ}C$, and the peak values rose to $48.1^{\circ}C$, $45.8^{\circ}C$ and $59.5^{\circ}C$, respectively. In spite of slight differences that resulted according to pavements, no coherent differentiating factor could be found. 3. The average WBGT of grass was the highest at $34.3^{\circ}C$ while the others were similar in the range of around $33{\pm}1^{\circ}C$. Meanwhile, the peak WBGT was highest with stone panel at $47.9^{\circ}C$. Though there were some differences according to pavements, and while grass seemed to be worst in terms of WBGT, it seems difficult to say ablolutely that grass was the worst because the measurement was conducted without ventilation and shade during summer daytime hours only, which had temperatures that rose to a dangerous degree(above $45^{\circ}C$ WBGT), withering the grass during the hottest period. The average WBGT resulted also showed that the thermal environment of the pavement without ventilation and shade were at an intolerable level for humans regardless of the pavement type. In summary, the results of this study show that ventilation and shade are more important factor than pavement type in terms of outdoor thermal comfort in summer daylight hours.