본 연구는 기온 상승에 따른 개별 콘크리트 슬래브의 팽창과 그로 인한 Pavemnent Growth 및 Blow-up 현상을 분석하고 예측하기 위 해 수행되었다. 기온이 상승함에 따라 슬래브는 팽창하며, 콘크리트 슬래브들의 팽창량은 팽창 줄눈 사이에 존재하는 모든 수축 줄눈 이 닫히게 될 정도로 발생하게 되고 그 결과 모든 슬래브들이 접촉하게 된다. 온도의 추가적인 증가로 슬래브가 계속해서 팽창하게 되면 팽창 줄눈의 수축 허용 폭을 초과하는 경우 일체화된 슬래브 내에서 압축 응력이 발생하게 되며, 이러한 현상을 "Pavement Growth"라 정의된다. 이로 인해 콘크리트 포장은 팽창하면서 파손이나 균열에서 좌굴 및 파괴와 같은 압력 관련 문제를 일으킬 수 있 다. 이는 교량 및 도로 내 접근 구조물과 같은 인접 구조물에도 손상을 줄 수 있다. 그러나 현재 사용 가능한 이론적 해결책이나 Pavement Growth 평가 방법과 Blow-up 예측에 관한 연구는 매우 제한적이다. 따라서 본 연구에서는 콘크리트 포장의 팽창을 예측하기 위해 Pavement Growth 및 Blow-up 분석 모델인 PGBA(Pavement Growth and Blow-up Analysis) Model을 개발하였다. 이 모델은 기후 조 건, 포장 구조, 재료, 팽창 줄눈 등의 요인을 고려하였다. 본 모델은 일체화된 슬래브가 팽창하여 팽창 줄눈의 수축 허용 폭을 초과하 는 시기를 결정한다. 슬래브와 기층 사이의 Frictional Darg 및 슬래브의 End Restraint으로 인해 발생하는 압축 응력을 계산 할 수 있는 것이다. 또한 Geometric Imperfection의 변화에 따른 Blow-up Stress를 검토하기 위해 Large-scale Blow-up Test를 진행하였으며, 측정된 결과를 Blow-up 발생 임계값으로 사용하였다. 일체화된 슬래브 내부에 발생하는 연도별 압축 응력을 예측하고 Blow-up Stress와 비교 하여 압축 응력이 Blow-up Stress를 초과하는 시점을 Blow-up 발생 시기로 선정하였다.

PURPOSES : Pavement growth (PG) is a phenomenon whereby the overall length of a concrete pavement increases. The increase in length induces an axial compressive force in the concrete pavement slab, resulting in blow-up and damage of adjacent structures, such as a bridge. PG is influenced by several interacting factors, including climatic conditions, pavement materials, joint systems, incompressible particles (IP) infiltrating the joints or cracks in the slab, and an expansion caused by reactive aggregates in the concrete. However, it is difficult to predict PG and blow-up due to various complicated factors. Therefore, in this study, the pavement growth and blow-up analysis (PGBA) package program was developed to predict the PG and blow-up potential. The PGBA can consider the pavement configuration, expansion joint (EJ) configuration, climatic conditions, and design reliability. To evaluate the effects of influencing factors — such as climatic data, EJ configuration, pavement structures and materials, and design reliability — on PG and occurrence time of blow-up, a numerical example was demonstrated and a sensitivity analysis was performed. METHODS : To predict the PG, the concrete temperature was calculated using an appropriate analytical model. The trigger temperature for pavement growth(TTPG) was predicted using a statistical equation that considers pavement age, joint spacing, and precipitation. An analytical solution for estimating the concrete slab movement was performed. Through the calculated TTPG and the amount of PG, the service life of the EJ (width of EJ) can be predicted compared to the allowable width. In addition, by using analytical and finite elements, the safe temperature(Tsafe) for preventing blow-up occurrence was calculated. The blow-up occurrence was assumed to occur when the variation between the concrete temperature and TTPG was larger than Tsafe. RESULTS :As a result of the sensitivity analysis of maximum temperature and precipitation, the temperature and precipitation increase and the EJ service life and possibility of blow-up decrease. Sensitivity analysis was performed on the thermal expansion coefficient, pavement thickness, base layer type, concrete elastic modulus, and joint rotational stiffness in the concrete pavement structure and properties. In the PGBA program, the coefficient of thermal expansion and the type of base layer significantly affect the EJ life, as do the possibility of blowup and the elastic modulus. The joint rotational stiffness and pavement thickness had little effect on the EJ life but were found to affect the possible timing of blow-up. As a result of the PGBA sensitivity analysis of the width and spacing, which are the specifications of the EJ, the life of the EJ and the possibility of blow-up increased as the joint width increased; however, the EJ life and blow-up increased as the EJ interval reached a certain value. It was found that the possibility of a blow-up occurrence decreased. The results for the PGBA program in extreme weather conditions, the life span of EJs, and the possibility of blow-up in normal climates were reduced by over 50 %. CONCLUSIONS : As a result of PGBA sensitivity analysis, it was found that the substrate type, thermal expansion coefficient, precipitation, and alkali-silica reaction had the greatest influence on pavement expansion and blow-up.

PURPOSES : Pavement growth (PG) of concrete pavement has been recognized as a major concern to highway and airport engineers as well as to road users for many years. PG is caused by the pressure generation in the concrete pavement as a result of a rise of the concrete temperature and moisture. PG could result in concrete pavement blowup and damage the adjacent or the nearby structures such as bridge structures. The amount of the PG is affected by the complicated interactions of numerous factors such as climatic condition, amounts of incompressible particles (IP) infiltration into the joints, pavement structure, and materials. Trigger temperature for pavement growth (TTPG) is defined as the concrete temperature when all transverse cracks or joints within the expansion joints completely close and generating a pressure in the pavement section. It is one of the most critical parameters to evaluate the potential of PG occurring in the pavement. Unfortunately, there are no available methods or guidelines for estimating TTPG. Therefore, this study aims to provide a methodology to predict TTPG of a concrete pavement section. METHODS : In this study, a method to evaluate the TTPG and its influencing factors using the field measured data of concrete pavement expansions is proposed. The data of the concrete pavement expansions obtained from the long-term monitoring of three concrete pavement sections, which are I-70, I-70N, and Md.458, in Maryland of United Stated, were used. The AASHTO equation to estimate the joint movement in concrete pavement was used and modified for the back-calculation of the TTPG value. A series of the analytical and numerical solutions presented in the literatures were utilized to predict the friction coefficient between the concrete slab-base and to estimate the maximum concrete temperature of these three pavement sections. RESULTS : The estimated maximum concrete temperature of these three pavement sections yearly exhibited relatively constant values, which range from 40 to 45 °C. The results of the back-calculation revealed that the TTPG of the I-70 and Md.58 sections decreased with time. However, the TTPG of the I-70N section tended to be relatively constant from the first year of the pavement age. CONCLUSIONS : The estimation of the TTPG for the three concrete pavement sections showed that the values of the TTPG gradually decreased although the yearly maximum concrete pavement temperature did not change significantly.