• International Journal of Highway Engineering
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• v.20 no.3
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• pp.47-57
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• 2018

PURPOSES : The permeable pavement type has been rapidly developed for solving problems regarding traffic noise in the area of housing complex and heavy rainwater drainage in order to account for the climate change. In this regards, the objective of this study is to figure out the characteristics of pavement types. METHODS : The laboratory test for deriving optimum asphalt content (OAC) was conducted using the mixtures of the permeable asphalt surface for the pavement surface from Marshall compaction method. Based on its results, the pavement construction at the test field was conducted. After that, the site performance tests for measuring the traffic noise, strength and permeability were carried out for the relative evaluation in 2 months after the traffic opening. The specific site tests are noble close proximity method (NCPX), Light falling deflectometer test (LFWD) and the compact permeability test. RESULTS : The ordered highest values of the traffic noise level can be found such as normal dense graded asphalt, drainage and porous structure types. In the results from LFWD, the strength values of the porous and drainage asphalt types had been lower, but the strength of normal asphalt structure had relatively stayed high. CONCLUSIONS :The porous structure has been shown to perform significantly better in permeability and noise reduction than others. In addition to this study, the evaluation of the properties and the determination of the optimum thickness for the subgrade course under the porous pavement will be conducted using ground investigation technique in the further research.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.163-170
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• 2005

Track substructure (ballast, subgrade) should have sufficient strength and uniform stiffness to fully support track superstructure (rail, fastener, sleeper). Vertical support stiffness of track is strongly influenced by the condition of ballast and subgrade layers. Therefore, the evaluation of the condition of track substructure is very important to evaluate the vertical support stiffness of track. This paper proposes the trackbed evaluation system, which is composed of Ground Penetrating Radar (GPR), Portable Ballast Sample. (PBS), and Light Falling Weight Deflectomete. (LFWD), to diagnose track substructure. The laboratory and field tests are performed to evaluate the applicability of the proposed trackbed evaluation system.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.866-875
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• 2006

The field plate load test a good potential for determining modulus since it measures both plate pressure and settlement. However, because The field plate load test is expensive and takes plenty of time for operation, it is very difficult to figure out the test characteristics of railroad roadbed in detail. For faster and economical operation, the Dynamic Cone Penetrometer(DCP) and the Light Falling Weight Deflectometer(LFWD) have been utilized for estimating the bearing capacity of railroad roadbed. The objective of this study is to determine the relationship between the test(PLT, DCP, LFWD) of the railroad roadbed in Korea. The DCP test and LFWD test for evauluating the strength of railroad roadbed materials produced in Korea are presented in this paper.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1332-1339
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• 2006

Hanging sleepers, which are not fully supported between the sleepers and the ballast, could cause large dynamic forces especially on high speed ballasted track. The dynamic forces resulting from insufficient supporting forces may badly affect the running stability and safety of train. These also accelerate track irregularities and deteriorate track components rapidly. Consequently, the hanging sleepers will lead to sharp increases in track maintenance cost. This paper introduces a rapid and easy method to detect hanging sleepers with portable light falling weight deflectometer (LFWD) and summarizes the results of experiments performed at the high speed ballasted track.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1373-1380
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• 2010

The plate loading test(PLT) and the field density test are mainly used on the construction of embankments to control the compaction of a limited layer thickness. These two test methods are very time consuming and inefficient, but they are still commonly used as the methods of quality control for soil compaction. In the last 3 decades, many devices such as geogauge, light falling weight deflectometer(LFWD) and dynamic cone penetrometer(DCP) etc., have been introduced into the engineering market with the objective of acquiring in situ stiffness properties of the compacted soil layers. Recently, a new type of sensor, called compactometer, which in mounted on the drum of a roller and measures impact forces continuously with GPS, called as Continuous Compaction Control(CCC), has come into use in many countries such as America, Germany, Japan and so on. The main objective of this paper is to assess the potential use of these new devices as quality control and assurance devices for compacted soil layers. Based on this study, compactometer and the LFWD results werestrongly correlated with the result obtained from the PLT and the field density test.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.636-643
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• 2008

The objective of this paper is to assess the potential use of the geogauge and the light falling weight deflectometer (LFWD) and the soil impact hammer as quality control/quality assurance $Q_C/Q_A$ devices for compacted soil layers. A comprehensive field experimental program considering variation of number of compaction, water contents and thickness of compaction layer was conducted on compacted layers of gravel sand. The geogauge, LFWD, the soil impact hammer and static load test (PLT) as a reference test were performed for the compacted layers. The geogauge elastic modulus, $E_G$, the LFWD dynamic modulus, ELFWD, empirical soil stiffness, $K_{30}$, obtained from soil impact hammer and soil stiffness directly obtained from PLT, $K_{30}$, were correlated with increasing number of compaction. The results of this study show that the geogauge, LFWD and the soil impact hammer, which are very simple to test, can be used as substituting devices for static PLT which is a conventional quality control/quality assurance $Q_C/Q_A$ devices for compacted soil layers.

• Journal of the Korean Geotechnical Society
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• v.34 no.2
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• pp.55-63
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• 2018

In order to support the load of the train with enough stiffness, a study on an effective method for the characterization of the stiffness of the compacted subgrade is required. In this study, the crosshole-type dynamic cone penetrometer (CDCP) is used for the stiffness characterization of the subgrade along the depth. For the application of the CDCP test, three points of compacted subgrades are selected as the study sites. For the study sites, CDCP test, in-situ density test, and light falling weight deflectometer (LFWD) test are conducted. As the results of CDCP tests, shear wave velocity profiles are obtained by using the travel times and the travel distances of the shear waves along the depth. In addition, maximum shear modulus ($G_{max}$) profiles are estimated by using the density of the subgrades and the shear wave velocity profiles. The averaged maximum shear moduli at each testing point are highly correlated with the dynamic deflection moduli ($E_{vd}$) determined by LFWD tests. Therefore, a reliable stiffness characterization of the subgrade can be conducted by using CDCP tests. In addition, because CDCP characterizes the stiffness of the subgrade along the depth rather than a representative value, CDCP test may be effectively used for the stiffness characterization of the subgrade.

• Journal of Construction Engineering and Project Management
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• v.2 no.2
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• pp.45-52
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• 2012

This study introduces a methodology to evaluate different types of non-nuclear technologies to see how they are competitive to the nuclear technology for quality control (QC) and quality assurance (QA) in soil condition measurement for highway pavement construction. The non-nuclear methods including the Electrical Density Gauge (EDG) and the Light Weight Deflectometer (LWD) were tested for their performance against a nuclear gauge, and traditional methods were used as baselines. An innovative way of comparing a deflection gauge to a density gauge was introduced. Results showed that the nuclear gauge generally outperformed the non-nuclear gauge in accuracies of soil density and moisture content measurements. Finally, a framework was developed as a guideline for evaluating various types of non-nuclear soil gauges. From other perspectives rather than accuracy, it was concluded that the non-nuclear gauges would be better alternative to the nuclear gauge when the followings are considered: (1) greater life-cycle cost savings; (2) elimination of intense federal regulations and safety/security concerns; and (3) elimination of licensing and intense training.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1152-1158
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• 2007

Although various fast and simple, testing devices have been developed in many countries such as the U.S, Japan, and European countries, these testing devices are not commonly used in Korea. In this study, compaction fur the field density test was carried out with a hand-guided vibrating roller. The results of the field density test were compared with those of the new testing devices such as the geogauge, soil impact hammer(CASPFOL), light falling weight deflectometer(LFWD), dynamic cone penetration(DCP). Regression analyses were conducted with the data from new testing devices. The analysis results showed that the correlation coefficients were high in the range of $70{\sim}95%$.

• Journal of the Korean Wood Science and Technology
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• v.47 no.1
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• pp.51-65
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• 2019

A wood-plastic composite (WPC) paver block was manufactured using wood chips waste through an extrusion process, and it was intended to be used for paving in basic rest areas. The first stage in this study covered preliminary tests in terms of flexural strength and dimensional swelling to determine the optimal WPC compounding mix condition, by variation of the WPC ingredients. Next, three different paver blocks including the WPC block, a non-porous cement block, and a porous cement block were tested in terms of various material properties in the laboratory. Finally, two outdoor test sections of the proposed paver blocks were prepared to simulate a basic rest area. Test results indicated that the flexural strength of the WPC paver blocks was about 1.6 times greater than that of the tested cement paver blocks. The WPC block pavement was unaffected by water buoyance as well as volume expansion due to swelling. Results from the impact absorbance test and light falling weight deflectometer (LFWD) test clearly showed that the WPC block paving system marginally satisfied the comfortable and safe hardness range from the pedestrians' perspective, while the results demonstrated that it is structurally sound for application as a road paving block.