Calibration on MEPDG Low Temperature Cracking Model and Recommendation on Asphalt Pavement Structures in Seasonal Frozen Region of China

Abstract

In order to implement the Mechanistic-Empirical Pavement Design Guide (MEPDG) to design and maintain asphalt pavements in China, it is necessary to calibrate transfer functions of distresses in MEPDG with local conditions, including traffics, environment, and materials as well as measured pavement distresses data in field. Comprehensive single factor sensitivity analyses of factors that influence thermal cracking of asphalt pavements were conducted utilizing the MEPDG low temperature cracking (LTC) model. Additionally, multiple factor sensitivity analyses were carried out as well, based on which pavement structures with sound thermal cracking resistance were recommended for seasonal frozen regions in China. Finally, the field data of thermal cracks on typical asphalt pavements in China was utilized to calibrate the LTC model in MEPDG. An improvement was proposed on MEPDG LTC model, after which was applied, the predicted thermal cracking from MEPDG LTC model agrees well with measured thermal cracking in China.

The Influence of Water on the Heat Loss of Hot Mix Asphalt

“…Convection currents cause the fluid to move up and vapor is formed only on the free surface of the fluid in the process of surface evaporation. The free convection heat transfer coefficient for fluids is proportional to (T S − T n ) 0.25 and the flux density of the absorbed heat is proportional to (T S − T n ) 1.25 [10,15,17,18]. An increase of the heat flux density (for greater temperature differences on the heat exchange surface: T S − T n = 3-30 K) increases the amount of steam bubbles which grow in diameter to come apart and move towards the surface of the fluid (nucleate boiling).…”

“…This results in vigorous mixing of the fluid, increasing the heat exchange intensity. In the nucleate boiling process the heat transfer coefficient is roughly proportional to (T S − T n ) 2 and the absorbed heat flux density is roughly proportional to (T S − T n ) 3 [10,15,18].…”

“…The test duration was 1 h. The thermal insulation (mineral wool) was additionally The flow type was established on the basis of the product of Grashof and Prandtl numbers. The values of Gr and Pr were determined for the properties of water (specific heat, viscosity, density and thermal expansion) at the average temperature (T m ) calculated with equation (10). With all the results for all the cases under analysis falling in the range of Gr•Pr > 2•10 7 we deal with a turbulent flow of heat.…”

“…In the bottom zone a higher content of voids reduces the tensile stress resistance of the layer (resulting in premature fatigue distress and low-temperature cracking, etc.) [9][10][11].…”

Low temperature properties of hot mix asphalts prepared with different polymer modified binders

“…Thermal fatigue cracking is one of the major failure modes for asphalt pavements that are subjected to alternating heating and cooling, while low-temperature cracking is a serious distress mode in very cold regions [1][2][3]. Failure by low temperature cracking occurs as a result of thermal stress buildup in the pavement.…”