To be better fit for highways, pavement systems are required to provide comfortable and safe driving and be structurally durable. Composite pavements can be an effective option as they are more durable by placing a high functional asphalt overlay on a rigid concrete base layer. In order to apply a composite pavement system to the field, it is necessary not only to develop technologies that prevent reflecting crack and deterioration of the base layer, but also to improve bonding performance of materials and ensure structural performance as a pavement system against traffic loading. In advanced countries like Japan, USA and Europe, high-functional composite pavement systems are being put into practice across new highway networks. In this study, we evaluated structural performance (rutting, reflecting crack, and deflection) by applying traffic loads of actual highways through an accelerated pavement tester (APT) of a composite pavement section made up of a quiet porous surface laid over a water-proofing layer, a continuously reinforced concrete base, and a lean concrete sub-base layer, which was developed with new pavement methods used for each layer prior to field application. The APT specimen was constructed with paving materials and equipment actually used on site in the same dimensions (W3.5m*L14m*H2m) as actual highway sections in Korea, and 3-axle double-wheel heavy load (45ton) cart type KALES(Korean Accelerated Loading and Environmental Simulator) traveling on the specimen in both directions was used to simulate traffic loading. After applying around 8,574,000 ESALs of traffic loads, no reflecting crack occurred on the asphalt surface of the composite pavement, without surface distress except for rutting. In order to examine what causes rutting of pavements, we surveyed thickness of pavements by layer and measured asphalt density.

The purpose of this study was to investigate the feasibility of converting the results obtained using different rutting performance tests. The correlation between the three simulation tests was analysed to determine the conversion coefficient factor. Two parameters (temperature and speed of simulation testing) were evaluated in this study. The results of this study have shown that the values obtained in the SALS test were lower than those obtained in the HWTT and UKWTT. The conversion of the SALS test results to the HWTT results yielded a good propensity value. The temperature is important parameter for determining the conversion coefficient factor.

Roller-compacted concrete (RCC) has been widely used for construction of pavements [1]. The strength of RCCP can be obtained from not only hydration of binder but also the aggregate interlock resulted from roller-compaction [2]. For this reason, RCCP normally achieves higher strength compared to conventional concrete pavement with similar cement content. Even though RCCP can be provided a good structural performance, it has been difficult to verify the long-term performance though actual field construction. Therefore, this study aimed to investigate the fatigue characteristics and crack development in RCCP based on full-scale fatigue test and accelerated pavement test. In case of full-scale fatigue tests, fatigue behavior was evaluated by using 1 m × 1 m dimensional RCC slab specimens obtained from the field in order to consider the field variability. Fatigue equation derived from this study shows that the number of load repetitions which causes fatigue failure at the same stress level is slightly larger than that of PCA fatigue equation. In order to evaluate the performance of RCCP, two phases of accelerated pavement test (APT) were conducted. In phase one, the performance of RCCP at two different strengths (35.6 and 30.4 MPa) was evaluated. In phase two, the performance of RCCP with different thickness (5, 7.5 and 10 cm) was investigated. The number of load repetition of fatigue crack occurrence in each section was compared to the estimated fatigue failure determined from fatigue equation of RCCP. The crack development in each section was compared to the AASHTO crack model for JPCP. Overall, it was confirmed that RCCP has equal or better performance compared to JPCP the estimation in term of fatigue cracking. The fatigue equation from PCA and cracking model from AAHTO can be used on RCCP at certain design thickness range.

PURPOSES : The objective of this study is to evaluate the effect of size and depth of cavities on the pavement failure using the full-scale accelerated pavement testing. METHODS: A full-scale testbed was constructed by installing the artificial cavities at a depth of 0.3 m and 0.7 m from the pavement surface for accelerated pavement testing. The cavities were made of ice with a dimension of 0.5 m*0.5 m*0.3 m, and the thickness of asphalt and base layer were 0.2 m and 0.3 m, respectively. The ground penetrating radar and endoscope testing were conducted to determine the shape and location of cavities. The falling weight deflectometer testing was also performed on the cavity and intact sections to estimate the difference of structural capacity between the two sections. A wheel loading of 80 kN was applied on the pavement section with a speed of 10 km/h in accelerated pavement testing. The permanent deformation was measured periodically at a given number of repetitions. The correlation between the depth and size of cavities and pavement failure was investigated using the accelerated pavement testing results. RESULTS : It is found from FWD testing that the center deflection of cavity section is 10% greater than that of the intact section, indicating the 25% reduction of modulus in subbase layer due to the occurrence of the cavity. The measured permanent deformation of the intact section is approximately 10 mm at 90,000 load repetitions. However, for a cavity section of 0.7 m depth, a permanent deformation of 30 mm was measured at 90,000 load repetitions, which is three times greater than that of the intact section. At cavity section of 0.3 m, the permanent deformation reached up to approximately 90 mm and an elliptical hole occurred at pavement surface after testing. CONCLUSIONS : This study is aimed at determining the pavement failure mechanism due to the occurrence of cavities under the pavement using accelerated pavement testing. In the future, the accelerated pavement testing will be conducted at a pavement section with different depths and sizes of cavities. Test results will be utilized to establish the criteria of risk in road collapse based on the various conditions.

본 논문은 시멘트 콘크리트 포장 위에 덧씌우기한 아스팔트 콘크리트 포장에서 발생하는 반사균열 제어를 위해 줄눈 실링재를 사용한 포장에서의 반사균열을 평가하기 위하여 수행되었다. 사용된 시험방법은 전단반사균열 모사실험 방법으로 실내에서 덧씌우기 아스팔트의 반사균열 저항성 시험을 위해 개발된 시험기법이다. 실험을 통하여 줄눈 실링재는 반사균열 제어에 효과가 있는 것으로 나타났다. 실링재 E를 사용하였을 때 피로수명은 가장 크게 나타났으나 수평변형은 상대적으로 크게 나타났고, B의 경우 수평변형은 가장 적게 나타났고 동적 안정도도 가장 크게 나타났다. 일반적으로 실링재의 인장강도가 높은 것일수록 혼합물의 반사균열저항성이 더 좋았다.

본 논문은 시멘트 콘크리트 포장 위에 덧씌우기한 아스팔트 콘크리트 포장에서 발생하는 반사균열 제어를 위해 줄눈 실링재를 사용한 포장에서의 반사균열을 평가하기 위하여 수행되었다. 사용된 시험방법은 전단반사균열 모사실험 방법으로 실내에서 덧씌우기 아스팔트의 반사균열 저항성 시험을 위해 개발된 시험기법이다. 실험을 통하여 줄눈 실링재는 반사균열 제어에 효과가 있는 것으로 나타났다. 실링재 E를 사용하였을 때 피로수명은 가장 크게 나타났으나 수평변형은 상대적으로 크게 나타났고, B의 경우 수평변형은 가장 적게 나타났고 동적 안정도도 가장 크게 나타났다. 일반적으로 실링재의 인장강도가 높은 것일수록 혼합물의 반사균열저항성이 더 좋았다.