Perpetual Pavements Design Criterions

This paper discusses the structural design criterions of perpetual pavement in China. Three representative methods were selected to analyze the relationship between the threshold strain and the service life. Then, the design criterions were statistically analyzed according to the calculation of the representative perpetual pavements of USA. Given the dynamic modulus and the axle load of 80KN, the average tensile strain at the bottom of the HMA is about 64 micro strains, and the average compressive strain at the top of the subgrade is about 170 micro strains. With static modulus parameters and 100KN axle load utilized, the Guangzhou to Shenzhen Freeway in China with cement treated course was analyzed. The calculations reveal that the strain is smaller than the threshold strain of USA perpetual pavements. Further more, the perpetual pavement structural design criterions for China were put forward as follows: the tensile strain at the bottom of the HMA should be less than 120 micro strains and the compressive strain at the top of the subgrade should be less than 280 micro, strains. A low stiffness is recommended for cement treated layer in a pavement. In the end, the perpetual pavement trial sections constructed in 2003 were used for checking calculations, which can satisfy the criterions of perpetual pavement of China.