In order to investigate the stress-dependent properties of hot-mix asphalt （HMA）,a dynamic modulus test was conducted on a group of AC-20 specimens at various stress states and loading frequencies,respectively.A use...In order to investigate the stress-dependent properties of hot-mix asphalt （HMA）,a dynamic modulus test was conducted on a group of AC-20 specimens at various stress states and loading frequencies,respectively.A user-defined material （UMAT ）subroutine incorporating stress-dependent constitutive model was developed and finite element （FE）simulation was utilized to confirm the validity of the UMAT.A three-dimensional （3D ）FE model for typical pavement structure was established,considering the HMA layer as a stress-dependent material and other layers as linear elastic materials.Periodic load was applied to the pavement model and the pavement responses were calculated,including dynamic modulus distributions,surface deflection,shear stress and tensile strain in the HMA layer,etc.Both test results and FE model predictions indicate that the dynamic modulus of asphalt concrete is sensitive to stress state and loading frequency.Using the nonlinear stress-dependent model results in greater predicted pavement responses compared with the linear elastic model.It is also found that the effects of stress-dependency on pavement responses become more significant as loading frequency decreases.展开更多
Marble dust waste powder generated by the marble cutting industry has a high alkalinity.In this research,the use of marble dust(MD)as a mineral filler substitute in hot mixed asphalt(HMA)was evaluated.The Marshall mix...Marble dust waste powder generated by the marble cutting industry has a high alkalinity.In this research,the use of marble dust(MD)as a mineral filler substitute in hot mixed asphalt(HMA)was evaluated.The Marshall mix design was used to determine the optimum bitumen content(OBC)for all of the mixtures.For each of the four MD contents,i.e.,0,2%,4%,and 6%by weight of the total aggregates,four different bitumen percentages were used.The results of the Marshall stability test showed that the optimum filler content was 4%MD.Samples were prepared with 0 MD in the control mix and varying percentages of MD as an alternate filler.In addition,MD aided in increasing the Marshall stability,rutting resistance,and permanent deformation and reduced the fatigue life of asphalt mixtures.As the percentage of MD increases,the rutting resistance and stiffness at high temperatures both increase.As the percentage of MD increases,the fatigue life reduces.Rut resistance in high-temperature conditions can be improved by using MD in HMA as a partial substitute for stone dust(SD).In areas where extensive MD waste is present,MD can be incorporated into HMA mixtures instead of conventional fillers.展开更多
基金Jiangsu Provincial Transportation Science and Technology Project(No.2011Y02-1-G1)
文摘In order to investigate the stress-dependent properties of hot-mix asphalt （HMA）,a dynamic modulus test was conducted on a group of AC-20 specimens at various stress states and loading frequencies,respectively.A user-defined material （UMAT ）subroutine incorporating stress-dependent constitutive model was developed and finite element （FE）simulation was utilized to confirm the validity of the UMAT.A three-dimensional （3D ）FE model for typical pavement structure was established,considering the HMA layer as a stress-dependent material and other layers as linear elastic materials.Periodic load was applied to the pavement model and the pavement responses were calculated,including dynamic modulus distributions,surface deflection,shear stress and tensile strain in the HMA layer,etc.Both test results and FE model predictions indicate that the dynamic modulus of asphalt concrete is sensitive to stress state and loading frequency.Using the nonlinear stress-dependent model results in greater predicted pavement responses compared with the linear elastic model.It is also found that the effects of stress-dependency on pavement responses become more significant as loading frequency decreases.
基金The author wishes to express his gratitude to the Department of Civil Engineering in the University of Engineering and Technology in Peshawar,for their assistance and guidance.
文摘Marble dust waste powder generated by the marble cutting industry has a high alkalinity.In this research,the use of marble dust(MD)as a mineral filler substitute in hot mixed asphalt(HMA)was evaluated.The Marshall mix design was used to determine the optimum bitumen content(OBC)for all of the mixtures.For each of the four MD contents,i.e.,0,2%,4%,and 6%by weight of the total aggregates,four different bitumen percentages were used.The results of the Marshall stability test showed that the optimum filler content was 4%MD.Samples were prepared with 0 MD in the control mix and varying percentages of MD as an alternate filler.In addition,MD aided in increasing the Marshall stability,rutting resistance,and permanent deformation and reduced the fatigue life of asphalt mixtures.As the percentage of MD increases,the rutting resistance and stiffness at high temperatures both increase.As the percentage of MD increases,the fatigue life reduces.Rut resistance in high-temperature conditions can be improved by using MD in HMA as a partial substitute for stone dust(SD).In areas where extensive MD waste is present,MD can be incorporated into HMA mixtures instead of conventional fillers.
