• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.288-291
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• 2011

최근 아스팔트 혼합물의 배합설계법은 기존에 주로 사용하던 빔 및 마샬 배합설계법에서 수퍼페이브 배합설계법으로 점차적으로 바뀌고 있는 추세이다. 수퍼페이브의 배합설계과정에서 중요한 사항 중의 하나는 선회다짐기를 사용하는 다짐방법이다. 아스팔트 포장은 노상 위에 보조기층, 기층, 표층의 순으로 구성되는데 노상은 포장 아래 약 1.0 m의 흙부분으로 포장과 일체로 구성되며 포장체에 작용하는 하중을 최종적으로 지지하는 층이다. 따라서, 수퍼페이브 배합설계법에서 사용하는 선회다짐기를 포장과 일체로 구성되는 노상의 다짐시험에도 적용한다면 각각의 포장층에 같은 원리의 다짐방법을 적용한다는 큰 의미가 있을 것으로 판단된다. 본 논문에서는 일반 노상토에 시멘트와 플라이애시를 첨가한 강화노상토를 선회다짐기를 이용하여 시편을 제작하였고, 각 시편에 대한 탄성계수를 1축압축시험, 공진주시험, LFWD를 이용해 각각 측정하여 각 결과물들의 상관관계를 추정하고자 한다.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.1-7
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• 2009

In order to use recycled aggregate as pavement base or subbase materials, the US and many other European countries have started research since the early 1980s. Korea also had a recycle idea as a plan for the vast amount of construction wastes due to the downtown renovation in the 1990s, but was not put into practical use. After the resources saving and recycle expedition law in 1994, wastes from construction sites that have more than a certain amount of construction budget were recycled as pavement base and subbase materials, but now, researches are being conducted to use them as paving materials. The use of construction wastes is meaningful in many ways. It helps the natural conservation and aggregate consumption, and also improves pavement performance. This research presents a development of cold-mixed reclaimed asphalt pavement materials using recycled aggregates.

• International Journal of Highway Engineering
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• v.6 no.2 s.20
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• pp.37-45
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• 2004

The asphalt concrete pavement takes various advantages of better riding quality, serviceability and easier maintenance. At the same time, it addresses a weak point of the premature failures due to rapid increasement of traffic volume, heavy vehicles and high temperature in summer. It increases the expenditure of maintenance and repair. In order to improve the performance of asphalt pavement avoiding this premature failure, the use reinforcements with geosynthetics have been considered. Geosynthetics are known as an effective reinforcement to restrain fatigue and reflective cracks in asphalt pavements. In this study, a comprehensive parametric study is conducted to capture the efficiency of geosynthetic-reinforcements using viscoelastic properties of the asphalt concrete(AC) layer. The investigated parameters were reinforcement location, AC layer thickness, temperature distribution across the AC layer and modulus of AC and base layer. As a result of observations, that reinforced asphalt concrete could be used effectively for improving resistance against fatigue cracks and permanent deformation. Especially, when a geogrid was placed at the interface between the asphaltic base and the subbase, tensile stress in the horizontal direction was significantly reduced.

• International Journal of Highway Engineering
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• v.1 no.2
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• pp.155-168
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• 1999

Asphalt pavement tends to rut in high temperature and to crack in cold temperature. The performance of asphalt pavement can be deteriorated by korean weather condition which has the four distinct seasons. In this study, the typical sections that may minimize rutting and fatigue were analyzed through the numerical model tests. The layered elastic theory , finite element method and visco elastic theory were utilized for these numerical model tests. From the various numerical model tests, it is found that an optimum design procedure was recommended. It was increasing the thickness of asphalt stabilized base with fixing the wearing course as 5cm the minimum specified thickness. The section was most beneficial in resting rutting and fatigue. From the analysis of the relative index on tensile strain and cost analysis, it was recommended that the thickness ratio of subbase and asphalt concrete is 1.0$\sim$2.5.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.81-87
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• 2006

The rubblization technique is breaking the aged concrete pavement slab into rubblized concrete aggregate, and use it as an base material at its original position, then builds overlay above the rubblized base. This method has been successively used in USA due to the advantage of good constructibility, cost-effectiveness as well as the capability of preventing of reflection cracks. However, constructibility and economic performance of rubblization on typical Korean concrete pavements needed to be investigate since to typical Korean concrete pavements have thick slab, as well include lean concrete subbase course. Multi-head type breaker suitable for Korean condition was designed and developed. This multi-head type breaker was designed to rubblize old concrete to the suggested optimum rubblized-depth and rubblized-concrete-aggregate size to prevent reflection crack and maintain high bearing capacity. This machine was used for the test of rubblization of old concrete pavement on a non-use old concrete and a in-serviced road. In these two tests, engineering properties of rubblized base and constructability and cost were investigated. In both tests, the old concrete rubblized to targeted size and depth, and high-level bearing capacity was achieved. Also, superior constructability and lower cost compared with traditional reconstruction was examined.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.105-111
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• 2010

It is very important to select carefully backfill materials and build for the structural integrity of abutment in bridge. In general, backfill materials of unbound crushed stones (SB-1) are used to provide the safety of abutment structure and to reduce differential settlement around abutment that is significantly related with performance of road pavement under working conditions. In this study, to evaluate the compatibility of backfill materials at abutment and to develop the abutment design program, i) basic properties of subgrade soils in Korea, ii) evaluation of deformational characteristics of backfill materials from RC/TS tests, cyclic TX tests and Creep tests were accomplished.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.1
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• pp.79-85
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• 1999

Use of soils with crushed expanded polystyrene(EPS) satisfied both recycling of industrial waste and development of new light-weight fill materials. Objectives of the study were to make the mixed the mixed soils with the crushed EPS and to suggest the most rational mixing ration as a fill material. A series of laboratory tests was performed to investigate the relationship between miximum dry density and optimum moisture contenr and to find the variation of CBR for mixtures with 3 soils and 2 sizes of the crushed EPS. Results of the test showed that the sizes fo the curshed EPS had a little effect on the properties of mixed soils. But gradatiion of soils and mixing ration with the crushed EPS were important factors to characterize compaction properties of the mixed soils.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.2
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• pp.66-81
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• 1989

The characteristics of resilient modulus(Mr) which dominates the life of pavement and the design of pavement were investigated on the test specimens which were cement treated and non-treated of the three different soil types. The results are summarized as follows : 1. The resilient modulus was decreased by increasing the cyclic deviator stress ($\sigma$d) , especially the resilient modulus was gradually decreased or sometimes increased when the value of ad was greater than 0.75- 1. 0kg/cm$^2$. 2. The resilient modulus was increased by increasing the homogeneous confined stress ($\sigma$do) and such phenomena were distinct on the coarse soils. 3. The resilient modulus was increased by increasing the ratio of confined stress(Kc), and this phenomena were eminent on the coarse soils too, and the higher permanent strain was showed by increasing the value of Kc. 4. In the drained cyclic triaxial compression test, the value of ad, Kc, and (Oho) was introduced by the following interrelated equations which were similar to the Mr model of Cole. Kcn/Mr=K1(J$_2$/ $\tau$oct)K2 ............. (coarse soli) Mcn/Mr=K3($\sigma$dp/ $\tau$f)k4 ...............(fine soils) 5. The stress path was not much affected by the value of Mr, however, moisture content, dry desity, and contant of fines affected the value of Mr. 6. In the soil-cement specimens, the resilient compression strain($\varepsilon$d) was decreased by the increment of the $\sigma$ho, and Mr was decreased by increasing the $\sigma$d 7. In the flexible pavement. the cement treated layer should be designed not to fail by the fatigue before the designed traffic load, and actually the pavement could cover the traffic load to a certain extent under the post-crack phase, therefore farther studies on this phenomena' are required in the design analysis. 8. The finite element computer program (ANALYS) was used for displacement analysis of pavement containing the cement-treated layer, The result showed that the program used for this analysis was proved to be usable.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.1-9
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• 2016

While the amount of construction waste has not been changed much in discharge for last 10 years, the recycled resources refined from construction waste have been mainly applied to low-leveled one such as reclamation, back-fill, road base or subbase and so on. Thus this study addresses the applicability of recycled fine aggregate as a replaceable material in precast concrete. To evaluate the possibility, both of dry and wet processes were adopted as well as steam curing, widely used in the field for rapid producing. Most important experimental parameters were driven through preliminary experiments and were evaluated in terms of concrete properties. It is found from aggregate-replacement tests that all of consistency and strengths of concrete were decreased as the ratio of recycled fine aggregate increased, and the amount of decrease can be estimated using proposed equations. Though the recycled fine aggregate showed a decrease of concrete properties more or less, the applicability in large volume as a constituent of precast product was well noted from experimental results.

• Journal of the Korean GEO-environmental Society
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• v.6 no.3
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• pp.17-23
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• 2005

In Korea, the production of reclaimed concrete materials has been increased due to the increase in the concrete structures taken down every year. The reclaimed concrete materials have been reused as road materials. However, the studies on their mechanical and environmental properties have been very limited. The recycled rate of the materials is currently low in Korea. This paper presents the investigation of mechanical and environmental properties of the reclaimed concrete materials, as well as the comparisons with those of gravel. For the evaluation of the mechanical and environmental characteristics, following tests were conducted on both reclamed materials and gravel; liquid limit, plasticity index, CBR, sand equivalent test, abrasion test, pH test, and column leaching test. The test results showed that the reclaimed concretes satisfy the requirements for use as roadbase, subbase, and subgrade materials, except base materials. The pH of reclaimed concrete materials was less than 11 and the leaching test results satisfied the regulatory requirement of Waste Management Act in Korea. Based on the investigations, it appears that the reclaimed concrete materials are environmentally safe and applicable for use as road materials.