The propagation of the cracks was based on the Paris law. In the low-temperature cracking model of the Superpave system, the asphalt mixture is assumed to be the viscoelastic material, and the one-dimensional Maxwell constitutive equation in the rheological mechanistic was utilized for the cracking prediction. There are three distress prediction models in Superpave design system: the low-temperature cracking model, the fatigue cracking model, and the permanent deformation model (rutting). The pavement distress model is used to predict the rutting, fatigue, and low-temperature cracking as it occurs with time or number of traffic repetitions based on the stress and strain computed by using the pavement response model in conjunction with the material property model and environment effects model. In the prediction of the fatigue cracking and permanent deformation, the pavement response model used in Superpave design system was based on a two-dimensional nonlinear finite element method. The pavement response model is used for the stress and strain of pavement structure under the traffic load and environmental conditions. MAAT design = MAAT average + K ασ MAAT MAAT average is the average value of annual average air temperature (☌). Z cr is the calculation depth of the asphalt mixture layer (mm). T eff(PD) is the effective temperature for the permanent deformation test (☌). MAPT is the annual average pavement temperature at 1/3 depth (☌). T eff(FC) is the effective temperature for the fatigue test (☌).
(1.34) for the estimation of the low-temperature grade. (1.33) is used for the estimation of the high-temperature grade, and Eq. In fact, the environment effect model refers just as to the temperature model of pavement, which will be used for the estimation of the highest and lowest temperature of pavement to select the proper asphalt binder, and for calculation of the pavement temperature at different depth as the test temperature of the mixture.įor the selection of the asphalt binder, Eq. Repeated shear at constant stress ratio (RSCSR) The m-value requirement must be satisfied in both cases.įrequency sweep at constant height (FSCH) If the creep stiffness is between 300 and 600 MPa, the direct tension failure strain requirement can be used in lieu of the creep stiffness requirement. f If the creep stiffness is below 300 MPa, the direct tension test is not required. e G*/sin δ is high-temperature stiffness and G* sin δ is intermediate temperature stiffness. d The mass change shall be less than 1% for either a positive (mass gain) or a negative (mass loss) change. However, in desert climates, the PAV aging temperature for PG 70-xx and above may be specified as 110☌.
Normally, the PAV aging temperature is 100☌ for PG 58-xx and above. c The PAV aging temperature is based on simulated climatic conditions and is one of three temperatures, 90☌, 100☌, or 110☌. b This requirement may be waived at the discretion of the specifying agency if the supplier warrants that the asphalt binder can be adequately pumped and mixed at temperatures that meet all applicable safety standards. a Pavement temperatures are estimated from air temperatures using an algorithm contained in the LTPP Bind program, which may be provided by the specifying agency or by following the procedures, as outlined in M 323 and R 35. Viscosity, T 316: b maximum 3 Pa s, test temperature (☌)ĭynamic shear, T 315: (3) G*/sin δ, c minimum 1.00 kPa, test temperature 10 rad/s (☌)ĭynamic shear, T 315: G*/sin δ, e minimum 2.20 kPa, test temperature 10 rad/s (☌)ĭynamic shear, T 315: G* sin δ, e maximum 5000 kPa, test temperature 10 rad/s (☌)Ĭreep stiffness, T 313: f, S, maximum 300 MPa, m-value, minimum 0.300, test temperature 60 s (☌)ĭirect tension, T 314: f, Failure strain, minimum 1.0%, test temperature 1.0 mm/min (☌)ĭynamic shear, T 315: c G*/sin δ, c minimum 1.00 kPa, test temperature 10 rad/s (☌)ĭynamic shear, T 315: G*/sin δ, e minimum 2.20 kPa, test temperature 10 rad/s (☌)ĭirect tension, T 314: f, failure strain, minimum 1.0%, test temperature 1.0 mm/min (☌)įor quality control of unmodified asphalt binder production, the measurement of the viscosity of the original asphalt binder may be used to supplement the dynamic shear measurements of G*/sin δ at test temperatures where the asphalt is a Newtonian fluid. Minimum pavement design temperature (☌) aįlash point temperature, T 48, minimum ☌ Average 7-day maximum pavement design temp (☌) a
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