• International Journal of Highway Engineering
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• v.17 no.2
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• pp.71-78
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• 2015

PURPOSES: This study set out to investigate the current state of microsurfacing in Texas and compared the results with the current state of the practice nationwide. METHODS: For this study, case studies were extracted from the existing literature and compared with the data obtained both from site visits by the research team and data obtained from a survey by Texas Department of Transportation (TxDOT) personnel. The successes and failures of microsurfacing are detailed and explanations of different issues are outlined. Forensic studies from Texas are included in the descriptions of those microsurfacings that failed when configured as part of the cape seals. RESULTS : Microsurfacing has been shown to be an effective pavement preservation technique when applied to an appropriate road, at an appropriate timing, and as a remedy for certain issues. The failures experienced in Texas can mostly be attributed to cape seals and an inability to recognize structurally faulty pavement. CONCLUSIONS : When applied to an appropriate road, at an appropriate timing, and as a remedy for certain issues, microsurfacing has been shown to perform well in numerous case studies. The majority of microsurfacing failures are the result of poor project selection, usually involving the treatment being applied to structurally unsound pavement.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.27-37
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• 2014

PURPOSES : The purpose of this study is to verify the causes of surface scaling at L-shoulder concrete structure. METHODS : From the literature reviews, mechanisms of frost damage were studied and material properties including strength, air void, spacing factor and scaling resistance of L-shoulder concrete structure were analyzed using core specimens taken by real fields. RESULTS : The spacing factor of air void has relatively high correlation of surface conditions : lower spacing factor at good surfacing condition and vice versa. If the compressive strength is high, even thought spacing factor does not reach the threshold value of reasonable durability, the surface scaling resistance shows higher value. Based on these test results, the compressive strength also provide positive effect on the surface scaling resistance. CONCLUSIONS : The main causes of surface scaling of L-shoulder could be summarized as unsuitable aid void amount and poor quality of air void structure. Secondly, although the compressive strength is not the governing factor of durability, but it shows the positive effect on the surface scaling resistance.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.41-49
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• 2009

Poor compaction of subgrade soil causes low stiffness and bearing capacity of sublayers so that faulting and differential settlements can be generated between new and old pavement surfaces in case of widening works. However, investigation of verifying the reason of producing the defects in the pavements are not performed in detail. In this study, several in-field tests including PMT and PBT were performed for obtaining stiffness of the sublayers in new and old pavements respectively of an widening project. Then, based on the obtained stiffness values and the measured deformations obtained by specially designed tilt meters, the main reasons of generating different deformations between the old and new pavement sections and the relationship between the deformation and stiffness are verified.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.49-54
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• 2007

Structural integrity assessment technique for pavement system is studied considering the uncertainties among the material properties. The artificial neural networks technique is applied for the inverse analysis to estimate the elastic modulus based on the measured deflections from the FWD test. A computer code based on the spectral element method was developed for the accurate and fast analysis of the multi-layered soil structures, and the developed program was used for generating the training and testing patterns for the neural network. Neural networks was applied to estimate the elastic modulus of pavement system using the maximum deflections with and without the uncertainties in the material properties. It was found that the estimation results by the conventiona1 neural networks were very poor when there exist the uncertainties and the estimation results could be significantly improved by adopting the proposed method for generating training patterns considering the uncertainties among material properties.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.45-53
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• 2012

Hollows are easily made and bearing capacity is lowered near underground structures of concrete pavement because of poor compaction and long term settlement of the ground. Distresses occur and lifespan is shortened because of larger stress induced by external loadings expected than that in the design. In this paper, the distresses of the concrete pavement slab over box culverts were investigated at the Korea Expressway Corporation(KEC) test road. The transverse cracking of the slabs over the culverts was compared between up and down lines with different soil cover depth. The box culvert without soil cover and concrete pavement were modeled and analyzed by the finite element method(FEM) to verify the transverse cracking at the test road. Wheel loading was applied after self weight of the pavement and temperature gradient of the concrete slab at Yeojoo, Gyeonggi where the test road is located were considered. Positions of maximum tensile stress and corresponding positions of the wheel loading were found for each loading combination. Joint position minimizing the maximum tensile stress was found and optimal slab length over the culverts with diverse size were suggested.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.546-553
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• 2022

This research has focused on identifying a significant cause of the pavement cracks and irregularities of roads in Changwon city which have been constructed using steel slag, an auxiliary-based material. It is important to note that the cracks and irregularities yield logistics inconvenience, the risk of traffic accidents, and increased road maintenance costs. X-ray diffraction analysis tests have been conducted in this study on the sample collected by pavement cutting and excavating the three target roads. It is well known that the primary cause of the expansion of steelmaking slag is the hydration reaction between CaO and MaO. While the reaction of CaO is completed within a few months, that of MgO is pretty slow depending on the firing temperature. The test results reveal that the MgO content of the testing samples is approximately 47% of the total average, and that of CaO is around 14% of the total average. Hence, these results make it possible to be understood that the expansion induced by the slow hydration reaction of MgO results in road uplift in the long term, resulting in the cracks and irregularities of roads.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.2
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• pp.47-57
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• 2023

The increase of impermeable area ratio is causing hydrologic cycle problems in urban areas and groundwater depletion in rural areas, permeable pavements are getting attention to expand permeable areas. The performance of the permeable concrete block pavement, which is part of the permeable pavement, is greatly affected by the porosity. In addition, the permeability coefficient is a major factor when designing permeable concrete block pavement. Existing porosity and permeability test methods have problems such as uneconomical or poor field applicability. The object of this study was to develop a methodology for evaluating porosity and permeability coefficient using a surface image of a permeable concrete block. Specimens are manufactured with various porosity ranges and porosity and permeability tests are performed. After surface image preprocessing, normalization and binarization methods were compared. Through this, the method with the highest correlation with the lab test result was determined. From the results, the PDR (pore determined ratio) was obtained. Simple linear regression analysis is performed with PDR and lab test results. The results showed a high correlation of R² more than 0.8, and the errors were also low.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.117-120
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• 2007

The main purpose of this paper is to introduce the early traffic opening-capable continuous multi-layer asphalt pavement maintenance method using electric arc furnace slag aggregate and emulsified asphalt to the actual construction sites. As well known, the previous surface treatment method of emulsified asphalt mixture have various shortcomings such as long work-time, traffic congestions, plastic deformation and poor evenness. Thus, the proposed method has enabled tile early traffic opening by utilizing the optimized emulsified asphalt after consideration of the climate and road conditions in Korea. The application of the electric furnace slag with $6\;{\sim}\;18\;mm$ thickness is helpful to become a environment-friendly construction method. And also, it has been improved enough to accommodate night-time works of mechanized construction activities for wearing course and control course.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.205-210
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• 1994

This study was conducted to evaluate performance of asphalt concretes under various densities, using Marshall specimens before and after freezing-and-thawing treatment. Six different compaction blows per side (20, 30, 40, 50, 60, 70 blows) were applied to specimens to produce different densities. Test results showed that the lower density specimens had the weaker resistance to freezing-and-thawing treatment. The density was an index of retaining fatigue life and displacement after freezing-and-thawing. Therefore, poor compaction in pavement was considered to be a major cause of early distress mechanisms such as rutting, ravelling and cracking, which were resulted in a reduced service life.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.33-43
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• 2006

Pull-out strength of tie-bin used in pavement construction is not an issue because those are embedded in newly placed concrete slabs. However, sufficient pull-out strength should be secured in widening constructions because, in case, the tie-bars are inserted into drilled holes of the existing slabs with liquid filler. Insufficient pull-out strength will result in lowered load transfer efficiency between adjacent slabs in addition to poor serviceability and durability due to joint widening. The pull-out strength of the tie-bars installed by current method is evaluated and improved methods are proposed. The field pull-out strength obtained by the current method was only 42.7% of required strength. Its first counterproposal is using to insert the liquid filler into drilled holes and stoppers to prevent it from flowing out of the holes. However, this method was not judged to secure desired level of quality control. The second counterproposal which substitutes the existing type of the tie-bars by SL anchor bolts was judged to secure sufficient pull out-strength in addition to the quality control and constructibility.