The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation.Asphalt concrete mixture was prepared at its optimum asphalt binder requ...The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation.Asphalt concrete mixture was prepared at its optimum asphalt binder requirement and compacted in slab mold with the aid of roller compaction.Beam specimens of 6.2 cm width,5.6 cm depth,and 40 cm length,were obtained from the slab samples with the aid of a diamond saw,and tested using controlled stress and strain techniques under dynamic flexural stresses.The viscoelastic properties such as the phase angle,cumulative dissipated energy,permanent deformation,flexural stiffness,and micro strain were monitored and modeled among the two testing techniques.It was noticed that higher micro strain and permanent deformation are detected when testing the asphalt concrete specimens under constant strain mode.However,higher phase angle,flexural stiffness,and energy dissipation could be observed under the constant stress mode of the test.展开更多
The fatigue-life of asphalt concrete is often related to environmental condition,loading condition,ageing,material composition and properties.This work investigates the influence of short and long term ageing of labor...The fatigue-life of asphalt concrete is often related to environmental condition,loading condition,ageing,material composition and properties.This work investigates the influence of short and long term ageing of laboratory beam specimens,asphalt percent,and testing temperature on fatigue life of asphalt concrete wearing course.Slab samples of(30 × 40 × 6)cm have been prepared,beam specimens of(40 × 5 × 6)cm were extracted from the asphalt concrete slab samples and tested for fatigue-life under the impact of three levels of micro strain(250,400,and[3]750)at(5,20,and 30)℃ before and after practicing long-term aging.It was observed that the fatigue-life decreased by(85 and 97)%,(87.5 and 97.4)%,(71.4 and 95.2)%after increasing the applied microstrain from(250 to 400 and 750)μƐfor control mixture and for mixtures subjected to shortand long-term ageing processes respectively.The fatigue-life increased by(142.8 and 257.1)%,(34.4 and 57.8)%and(10 and 30)%when the asphalt content increased from(4.4 to 4.9 and 5.4)%for specimens practicing the applied microstrain of(250,400 and 750)μƐrespectively.It can be concluded that the fatigue life increases by a range of(two to fifteen)folds when the testing temperature increases from(5 to 20 and 30)℃ respectively.展开更多
Various modes of compacting the asphalt concrete mixture can create mechanically different behaviour of the prepared specimens and can alter its sustainability.An attempt has been made in the present assessment to pre...Various modes of compacting the asphalt concrete mixture can create mechanically different behaviour of the prepared specimens and can alter its sustainability.An attempt has been made in the present assessment to prepare asphalt concrete specimens by implementation of three modes of compaction,the gyratory,the roller,and the Marshall hammer.The specimens were prepared at the target bulk density of Marshall method at optimum asphalt content.Extra specimens were prepared at 0.5%asphalt below and above the optimum.Core specimens have been obtained from the roller compacted slab samples.The specimens were tested for the Marshall stiffness,tensile,and shear strength.It was observed that at optimum asphalt content,the indirect tensile strength declines by(18.8 and 70.5)%for gyratory and roller compacted specimens respectively as compared with hammer compacted specimens.At optimum asphalt content,the shear strength declines by(70.5 and 82.2)%while Marshall stiffness declines by(10.2 and 44.8)%for hammer and roller compacted specimens as compared with that of gyratory compacted specimen.Specimens prepared by gyratory compaction are less susceptible to the change in the testing temperature as compared with other modes of compaction.It is recommended to consider the mode of compaction to suit the required design property of sustainable asphalt concrete mixture.展开更多
文摘The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation.Asphalt concrete mixture was prepared at its optimum asphalt binder requirement and compacted in slab mold with the aid of roller compaction.Beam specimens of 6.2 cm width,5.6 cm depth,and 40 cm length,were obtained from the slab samples with the aid of a diamond saw,and tested using controlled stress and strain techniques under dynamic flexural stresses.The viscoelastic properties such as the phase angle,cumulative dissipated energy,permanent deformation,flexural stiffness,and micro strain were monitored and modeled among the two testing techniques.It was noticed that higher micro strain and permanent deformation are detected when testing the asphalt concrete specimens under constant strain mode.However,higher phase angle,flexural stiffness,and energy dissipation could be observed under the constant stress mode of the test.
文摘The fatigue-life of asphalt concrete is often related to environmental condition,loading condition,ageing,material composition and properties.This work investigates the influence of short and long term ageing of laboratory beam specimens,asphalt percent,and testing temperature on fatigue life of asphalt concrete wearing course.Slab samples of(30 × 40 × 6)cm have been prepared,beam specimens of(40 × 5 × 6)cm were extracted from the asphalt concrete slab samples and tested for fatigue-life under the impact of three levels of micro strain(250,400,and[3]750)at(5,20,and 30)℃ before and after practicing long-term aging.It was observed that the fatigue-life decreased by(85 and 97)%,(87.5 and 97.4)%,(71.4 and 95.2)%after increasing the applied microstrain from(250 to 400 and 750)μƐfor control mixture and for mixtures subjected to shortand long-term ageing processes respectively.The fatigue-life increased by(142.8 and 257.1)%,(34.4 and 57.8)%and(10 and 30)%when the asphalt content increased from(4.4 to 4.9 and 5.4)%for specimens practicing the applied microstrain of(250,400 and 750)μƐrespectively.It can be concluded that the fatigue life increases by a range of(two to fifteen)folds when the testing temperature increases from(5 to 20 and 30)℃ respectively.
文摘Various modes of compacting the asphalt concrete mixture can create mechanically different behaviour of the prepared specimens and can alter its sustainability.An attempt has been made in the present assessment to prepare asphalt concrete specimens by implementation of three modes of compaction,the gyratory,the roller,and the Marshall hammer.The specimens were prepared at the target bulk density of Marshall method at optimum asphalt content.Extra specimens were prepared at 0.5%asphalt below and above the optimum.Core specimens have been obtained from the roller compacted slab samples.The specimens were tested for the Marshall stiffness,tensile,and shear strength.It was observed that at optimum asphalt content,the indirect tensile strength declines by(18.8 and 70.5)%for gyratory and roller compacted specimens respectively as compared with hammer compacted specimens.At optimum asphalt content,the shear strength declines by(70.5 and 82.2)%while Marshall stiffness declines by(10.2 and 44.8)%for hammer and roller compacted specimens as compared with that of gyratory compacted specimen.Specimens prepared by gyratory compaction are less susceptible to the change in the testing temperature as compared with other modes of compaction.It is recommended to consider the mode of compaction to suit the required design property of sustainable asphalt concrete mixture.
