ผลกระทบของความผันแปรตามฤดูกาลที่มีต่อการออกแบบและประเมินทางลาดยางในประเทศไทย / นวพล พรหมจารีย์ = Effects of seasonal variation on the design and evaluation of flexible pavement in Thailand / Nawapol Brahmajaree
The primary objective of the research is to study of the impacts of climatic condition on flexible pavement behavior by finding seasonal variations in both of pavement strength and its layer materials properties such as asphalt concrete elastic modulus, granular base modulus and subgrade resilient modulus which vary throughout a year caused by temperature itself, moisture itself or the combination of both. In addition, the research came out with a method to incorporate the effects of seasonal variation into the design of pavement according to the Thai climate. Data collection was conducted by Falling Weight Deflectometer (FWD) testing on the flexible pavement of the highway number 309. The test was done monthly, over one year, from April 2004 to March 2005. Simultaneously, asphalt concrete layer temperatures and moisture content in pavement structure were measured. The deflection data of the testing were backcalculated by ELMOD program, in order to find the pavement layers moduli. Results reveal that both asphalt concrete modulus and subgrade modulus vary according to season caused by changing in temperature and moisture respectively, plotted results in time series functions that show the sinusoidal shaped curves, which can be applied into the mechanistic-empirical design. Secondly, the relationship between ratio of asphalt concrete modulus to asphalt concrete modulus at 35 ํC and the middepth asphalt concrete temperature is close to the temperature correction for asphalt concrete modulus developed by the Pavement Technology Project (PTP). In addition, the weighting factor was determined for investigating the representative subgrade modulus that used in the pavement design by AASHTO method.