SungWoo Ryu

Development of Cement-Treated Base Material for Reducing Shrinkage Cracks

This paper describes an approach to minimizing the amount of shrinkage cracking in a cement-treated base (CTB). CTB is a stiff base that features higher rutting resistance and reduced fatigue cracking because of its ability to distribute traffic loads. However, it has not been applied to asphalt pavement in South Korea because of the possibility of reflection cracks. The goal of this study was to develop a cement-treated base with a lower shrinkage and thereby prevent cracks. After factors contributing to dry shrinkage were identified and the composition and properties of each admixture were analyzed, laboratory and field tests were designed and performed. The preliminary test results suggested a mix design of 25% fly ash. The amount of cement was set at 7% for all mixes to satisfy the specification standard for allowed strength in South Korea. On the basis of the experiment results, and considering strength, shrinkage, and economic efficiency, two mix designs were selected: a mixture containing 25% fly a...

Performance of Permeable Block Pavements in Accelerated Pavement Test and Rainfall Simulation

As industrialization advances, the increase in impermeable areas in urban regions has changed the water circulation system. Hence, many environmental issues such as heat islands and city floods have arisen. To solve this issue, related research with a high budget allocation is currently being carried out. A method of addressing this issue is to utilize permeable block pavements. The bearing capacity and hydrological efficiency of permeable block pavement with different base types was evaluated in this study using two accelerated pavement testings (APTs). Rutting was evaluated by performing a comparative analysis in each permeable block pavement. Furthermore, the hydrological characteristics were reviewed through a rainfall simulation experiment. The results of APT show that performance of permeable block pavements varies depending on the base type and traffic volume. Based on the result, it was demonstrated that the permeable block pavement is applicable for a vehicle road as well as the sidewalk. In addition, it was demonstrated that this pavement can improve the water circulation system.

Evaluation of the Load Dissipation Behavior of Concrete Block Pavements with Various Block Shapes and Construction Patterns

AbstractIn concrete block pavement, individual blocks are laid in a predetermined pattern to create a surface interlocked with joint filler that has some discontinuities rather than continuous pavi...

JCP Behavior with Traffic and Temperature Loadings: Analysis of a Test Road in Korea

AbstractBecause traffic and environmental loadings cause concrete pavement failure, a large budget is allocated for maintenance. Through understanding the effect of traffic and temperature loadings...

Performance Evaluation of the Runoff Reduction with Permeable Pavements using the SWMM Model

PURPOSES: This study aims to evaluate the runoff reduction with permeable pavements using the SWMM analysis. METHODS: In this study, simulations were carried out using two different models, simple and complex, to evaluate the runoff reduction when an impermeable pavement is replaced with a permeable pavement. In the simple model, the target area for the analysis was grouped into four areas by the land use characteristics, using the statistical database. In the complex model, simulation was performed based on the data on the sewer and road network configuration of Yongsan-Gu Bogwang-Dong in Seoul, using the ArcGIS software. A scenario was created to investigate the hydro-performance of the permeable pavement based on the return period, runoff coefficient, and the area of permeable pavement that could be laid within one hour after rainfall. RESULTS : The simple modeling analysis results showed that, when an impervious pavement is replaced with a permeable pavement, the peak discharge reduced from to . This represents a reduction of approximately 37.6%. The peak discharge from the whole basin showed a reduction of approximately 11.0%, and the quantity decreased from to . The total flowoff reduced from to , i.e., by approximately 10.9%. In the complex model, performed using the ArcGIS interpretation with fewer permeable pavements applicable, the return period and the runoff coefficient increased, and the total flowoff and peak discharge also increased. When the return period was set to 20 years, and a runoff coefficient of 0.05 was applied to all the roads, the total outflow reduced by , and the ratio reduced to 11.7%. When the return period was increased from 20 years to 30 and 100 years, the total outflow reduction decreased from 11.7% to 8.0% and 5.1%, respectively. When a runoff coefficient of 0.5 was applied to all the roads under the return period of 20 years, the total outflow reduction was 10.8%; when the return period was increased to 30 and 100 years, the total outflow reduction decreased to 6.5% and 2.9%, respectively. However, unlike in the simple model, for all the cases in the complex model, the peak discharge reductions were less than 1%. CONCLUSIONS : Being one of the techniques for water circulation and runoff reduction, a high reduction for the small return period rainfall event of penetration was obtained by applying permeable pavements instead of impermeable pavement. With the SWMM analysis results, it was proved that changing to permeable pavement is one of the ways to effectively provide water circulation to various green infrastructure projects, and for stormwater management in urban watersheds.

Performance Evaluation of Interlocking Block Pavement for Low Speed Highway

PURPOSES:This study aims to evaluate the performance of interlocking block pavement system for low speed highway. METHODS : Through on-site monitoring, environmental impact assessment of interlocking block pavement such as heat island reduction, traffic safety, noise pollution were evaluated as compared with asphalt pavement. Also the pavement condition and roughness were evaluated according to performance period. RESULTS : Surface temperature of interlocking block pavement was about 7 degree lower than asphalt pavement in midsummer. Compared to asphalt pavement, vehicle speed reduction effect of interlocking block pavement was about 2kph. For low speed driving, the noise pollution was measured at a similar level for both asphalt and interlocking block pavement. After 42month service period, the breakage of block was only 0.24% for the whole surveyed area. IRI of interlock block pavement was estimated within the range of 5~8m/km. CONCLUSIONS : Depending on the performance monitoring results such as heat island reduction, providing traffic safety and keeping a good pavement condition for a long service period, it assures that interlocking block pavement was applicable for low speed road.

Development of A Strength Test Method for Irregular Shaped Concrete Block Paver

PURPOSES:This study aims to develop a strength test method for irregularly shaped concrete block paver. METHODS : Ten (10) different types of concrete block pavers including porous and dense blocks were tested for strength capacities. Destructive and non-destructive methods were used to develop a strength test method for irregularly shaped concrete block paver. The flexural strength evaluation was conducted in accordance to KS F 4419, while compressive strength was conducted with a 45.7mm-diameter core specimen. The impact echo test method was used to evaluate the elastic modulus. Finally, regression analysis was used to investigate the relationship between flexural strength, compressive strength and elastic modulus based on their corresponding test results. RESULTS : The flexural strength of the tested block pavers ranged from 4MPa to 10MPa. At 95% confidence level, the coefficients of determination between compressive-flexural strength relationship and compressive strength-elastic modulus relationship were 0.94 and 0.84, respectively. These coefficients signified high correlation. CONCLUSIONS : Using the test method proposed in this study, it will be easier to evaluate the strength of irregularly shaped concrete block pavers through impact echo test and compressive test, instead of the flexural test. Relative to the flexural strength requirement of 5MPa, the minimum values of compressive strength and elastic modulus, as proposed, are 13.0MPa and 25.0GPa, respectively.

A Study on the Optimization of Curing Technology for Improving Properties of Concrete Pavement

PURPOSES : This study is to suggest time to spray curing compound, the amount of curing compound, and the number of times to spray curing compound based on indoor tests. METHODS : Based on the literature review, two methods are used in this study, One is test for water retention of concrete curing material and the other is test for abrasion resistance of concrete surfaces by the rotating-cutter method. Through those methods, curing compound was evaluated. RESULTS : The result of the laboratory experiment for time to spray curing compound indicates that 30 minutes after placing concrete is optimal. For the amount of curing compound, is the minimum quantity for both concretes. Through test of the number of times to spray curing compound, method to spray the whole amount of curing compound in twice is more efficient than it to spray the whole amount at a time. Also, method of separately 30-50 minutes spray is better than method of separately 10-30 minutes spray. CONCLUSIONS : From the testing results, it can be proposed that optimum time to curing compound is minutes, is efficient for spraying the whole amount of curing compound at a time, and is the best for spraying the whole amount of curing compound in twice, which sprays it in 20 minutes after 30 minutes from placing concrete.