최근 급격히 변하는 기후 및 다양한 영향으로 인한 도로의 파손이 증가하는 추세를 보이고 있다. 그 중 포장의 성분 에 따른 강도의 문제로 파손이 발생되기도 하는데, 강도를 측정하는데 있어 아스팔트 혼합물은 탄성과 점성의 성질을 동시에 나타내기 때문에 온도 및 하중재하속도, 간격을 매우 중요한 인자로 고려한다. 이러한 인자들을 만족시키기 위 하여 국내에서는 고가의 장비에 의존하고 있는 실정이다. 이러한 점에 대해 본 연구에서는 상대적으로 저렴한 동시에 빠르게 동탄성계수를 도출해 내기 위해서 IRT시험을 도입하였다. 또한 IRT 시험법 평가를 위하여 공신력을 가지고 있 는 MTS 장비의 결과와 비교하고자 한다. MTS 810시스템을 사용하여 동탄성계수를 측정하는데 있어 실험조건으로 하중주기 주파수는 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.02KHz로 설정하였으며, 실험온도는 5, 20, 40, 54℃로 설정하여 수행하였다. 일축압축/인장시험 수행에 서는 공시체에 120°간격으로 85mm 변형측정자기센서(Linear Variable Differential Transformer, LVDT) 4기를 설치 하여 수직변형을 측정하는 방식으로 수행되었다. IRT 시험에서는 아래 Figure 2와 같이 공시체를 고정시킨 후 한쪽 면을 쇠구슬로 충격을 가한다. 이때 공시체 양 측면에 가속도계를 설치하여, 쇠구슬로 인해 발생하는 외력에 대한 신호를 계측 한다. 이 아날로그 신호는 펄스장비를 통하여 디지털 신호화 되어지며, 이때 신호의 전파속도가 상당히 빠르기 때문에 신 호처리와 공진주파수를 찾기 위하여 시간에 대한 디지털신호를 주파수에 대한 Frequency Function으로 변환하는 과정을 수행한다.

PURPOSES: The dynamic modulus can be determined by applying the various theories from the Impact Resonance Testing(IRT) Method. The objective of this paper is to determine the best theory to produce the dynamic modulus that has the lowest error as the dynamic modulus data obtained from these theories(Complex Wave equation Resonance Method related to either the transmissibility loss or not, Dynamic Stiffness Resonance Method) compared to the results for dynamic modulus determined by using the Universal Testing Machine. The ultimate object is to develop the predictive model for the dynamic modulus of a Linear Visco-Elastic specimen by using the Complex Wave equation Resonance Method(CWRM) came up for an existing study(S. O. Oyadiji; 1985) and the Optimization. METHODS: At the destructive test which uses the Universal Testing Machine, the dynamic modulus results along with the frequency can be used for determining the sigmoidal master curve function related to the reduced frequency by applying Time-Temperature Superposition Principle. RESULTS: The constant to be solved from Eq. (11) is a value of 14.13. The reduced dynamic modulus obtained from the IRT considering the loss factor related to the impact transmissibility has RMSE of 367.7MPa, MPE of 3.7%. When the predictive dynamic modulus model was applied to determine the master curve, the predictive model has RMSE of 583.5MPa, MPE of 3.5% compared to the destructive test results for the dynamic modulus. CONCLUSIONS: Because we considered that the results obtained from the destructive test had the most highest source credibility in this study, the dynamic modulus data obtained respectively from DSRM, CWRM were compared to the results obtained from the destructive test by using th IRT. At the result, the reduced dynamic modulus derived from DSRM has the most lowest error.

PURPOSES: The dynamic modulus for a specimen can be determined by using either the non-destructed or destructed testing method. The Impact Resonance Testing (IRT) is the one of the non-destructed testing methods. The MTS has proved the source credibility and has the disadvantages which indicate the expensive equipment to operate and need a lot of manpower to manufacture the specimens because of the low repeatability with an experiment. To overcome these shortcomings from MTS, the objective of this paper is to compare the dynamic modulus obtained from IRT with MTS result and prove the source credibility. METHODS: The dynamic modulus obtained from IRT could be determined by using the Resonance Frequency (RF) from the Frequency Response Function (FRF) that derived from the Fourier Transform based on the Frequency Analysis of the Digital Signal Processing (DSP)(S. O. Oyadigi; 1985). The RF values are verified from the Coherence Function (CF). To estimate the error, the Root Mean Squared Error (RMSE) method could be used. RESULTS : The dynamic modulus data obtained from IRT have the maximum error of 8%, and RMSE of 2,000MPa compared to the dynamic modulus measured by the Dynamic Modulus Testing (DMT) of MTS testing machine.. CONCLUSIONS: The IRT testing method needs the prediction model of the dynamic modulus for a Linear Visco-Elastic (LVE) specimen to improve the suitability.

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.