The use of concrete wastes in asphalt treated base (ATB) not only prevents environmental pollution but also protect stone resources. But the strength of the concrete wastes is often weaker than nature aggregates and t...The use of concrete wastes in asphalt treated base (ATB) not only prevents environmental pollution but also protect stone resources. But the strength of the concrete wastes is often weaker than nature aggregates and the binding properties with asphalt is poor. So it difficult to meet the requirements of asphalt treated base. In this paper,The organosilicone waterproofing material is used to improve the performance of concrete wastes and the long term immersing frozen-thaw cycle test were used to investigate the anti-stripping performance of limestone asphalt mixture,concrete wastes asphalt mixture and concrete wastes asphalt mixture having treated by organosilicone waterproofing material. The experimental results show that organosilicone waterproofing material can improve the water stability of asphalt mixture. The use of concrete wastes in ATB is achievable.展开更多
A new novel function materials, structure self-monitoring asphalt-based composite was introduced. The results show that the output resistance of electrically conductive asphalt-based composites would change under cycl...A new novel function materials, structure self-monitoring asphalt-based composite was introduced. The results show that the output resistance of electrically conductive asphalt-based composites would change under cyclic loading and vehicle loading action. The resistance change of conductive asphalt-based composites was aroused by the variation of its interior structure. When the fatigue failure was studied, the larger cracks cut the continuous electrically conductive path and the electron is difficult to overcome the potential barrier of gap. In the early period, the slight deformation and microcrack may be recovered due to the viscoelasticity character of asphalt, which leads to some cracks close again, the output resistance changes a little. But with the shear process performs continuously, the cracks become larger and larger, which would cut the conductive path and block off the transition of electrons, and if the cracks are large enough, the pitch-matrix composites containing carbon fillers will lose electrically conductive function. When the rutting failure was studied, the flowage of conductive substance results in the decrease of substance due to electrically conducting and conductive path decreasing. The decrease of electron volume contribute to electrically conducting and large stone aggregate prevent the electron from transiting. In a word, the variation of output resistance is aroused by the variation of interior structure completely.展开更多
The relationship between thermal conductivity and properties of mixing particles is required for quantitative study of heat transfer processes in asphalt-based materials. In this paper, we measured the e？ective ther-...The relationship between thermal conductivity and properties of mixing particles is required for quantitative study of heat transfer processes in asphalt-based materials. In this paper, we measured the e？ective ther- mal conductivity of asphalt-based materials with thermal conduction （graphite） and insulation （cenosphere） powders modification. By taking account of the particle shape, volume fraction, the thermal conductivity of filling particles and base asphalt, we present a new differential effective medium formula to predict the thermal conductivity modification in asphalt-based composite. Our theoretical predications are in good agreement with the experiment data. The new model can be applied for predicting the thermal properties of asphalt-based mixture, which is available for most of thermal modification in two-phase composites.展开更多
In this study,the regenerative effects of different regenerants on aged SBS-modified asphalt from different perspectives were investigated,including their conventional properties,viscoelastic behavior,creep-related pr...In this study,the regenerative effects of different regenerants on aged SBS-modified asphalt from different perspectives were investigated,including their conventional properties,viscoelastic behavior,creep-related properties,and micromorphology.Base oils composed of different proportions of aromatic and saturated hydrocarbons as well as the styrene-butadiene-styrene(SBS)restorer were used to prepare the regenerants.The results showed that the components of the base oil of the regenerant played a crucial role in determining the characteristics and performance of the recycled SBSmodified asphalt.Regenerants containing a high proportion of aromatics dissolved the hard segment in the SBS restorer,thereby delaying the effect of a reduction in the regenerants on the performance of the aged asphalts at a high temperature.Regenerants containing a high proportion of saturates dissolved the soft segment in the SBS restorer to enhance the lowtemperature performance of the recycled asphalts.In addition,the stress sensitivity of the recycled asphalts increased with the fraction of aromatics in the regenerant.As the aromatic content of the base oil components of the regenerants increased and their saturate content decreased,the state of dispersion of the SBS phase in the recycled SBS-modified asphalts improved.The optimal content of aromatics in the base oil of the regenerants should be set in the range of 33%to 47%to ensure the adequate performance of the recycled asphalts and a high efficiency of the SBS restorer.展开更多
The objective of this project was to characterize the freeze-thaw properties of recycled concrete(RCA)and asphalt(RAP)as unbound base and to assess how they behaved in the field for nearly 8 years.This paper includes ...The objective of this project was to characterize the freeze-thaw properties of recycled concrete(RCA)and asphalt(RAP)as unbound base and to assess how they behaved in the field for nearly 8 years.This paper includes an examination of existing information,laboratory studies of freeze-thaw behavior,and evaluation of data from Mn ROAD field-test sections in a seasonally cold region,i.e.,in Minnesota,USA.Test sections were constructed using recycled materials in the granular base layers at the Mn ROAD test facility.One test section included 100%RAP,another 100%RCA,a third one a 50/50blend of RCA/natural aggregate,and a fourth one only natural aggregate(Class 5)as a control.The stiffness(i.e.,elastic modulus)was monitored during construction and throughout the pavement life by the Minnesota Department of Transportation,along with the variation of temperatures and moisture regimes in the pavement to determine their effects on pavement performance.The resilient modulus of each material was determined by bench-scale testing in accordance with NCHRP 1-28a,as well as by field-scale tests incorporating a falling-weight deflectometer.Specimens were subjected to as many as 20 cycles of freeze-thaw in the laboratory,and the change in their resilient modulus was measured.In the field-test sections constructed with the same materials as the base course,temperature,moisture,and field modulus(from fallingweight deflectometer tests)were monitored seasonally for nearly 8 years.From the temperatures in the base course layer,the number of freeze-thaw cycles experienced in the field was determined for each test section.Inferences were made relative to modulus change versus freeze-thaw cycles.Conclusions were drawn for long-term field performances of the recycled base(RAB)in comparison to natural aggregate.展开更多
文摘The use of concrete wastes in asphalt treated base (ATB) not only prevents environmental pollution but also protect stone resources. But the strength of the concrete wastes is often weaker than nature aggregates and the binding properties with asphalt is poor. So it difficult to meet the requirements of asphalt treated base. In this paper,The organosilicone waterproofing material is used to improve the performance of concrete wastes and the long term immersing frozen-thaw cycle test were used to investigate the anti-stripping performance of limestone asphalt mixture,concrete wastes asphalt mixture and concrete wastes asphalt mixture having treated by organosilicone waterproofing material. The experimental results show that organosilicone waterproofing material can improve the water stability of asphalt mixture. The use of concrete wastes in ATB is achievable.
基金Project (2004ABB019) supported by the Outstanding Youth Foundation of Hubei Province, China project (NCET-05-0656) supported by the New Century Excellent Talents in Wuhan University
文摘A new novel function materials, structure self-monitoring asphalt-based composite was introduced. The results show that the output resistance of electrically conductive asphalt-based composites would change under cyclic loading and vehicle loading action. The resistance change of conductive asphalt-based composites was aroused by the variation of its interior structure. When the fatigue failure was studied, the larger cracks cut the continuous electrically conductive path and the electron is difficult to overcome the potential barrier of gap. In the early period, the slight deformation and microcrack may be recovered due to the viscoelasticity character of asphalt, which leads to some cracks close again, the output resistance changes a little. But with the shear process performs continuously, the cracks become larger and larger, which would cut the conductive path and block off the transition of electrons, and if the cracks are large enough, the pitch-matrix composites containing carbon fillers will lose electrically conductive function. When the rutting failure was studied, the flowage of conductive substance results in the decrease of substance due to electrically conducting and conductive path decreasing. The decrease of electron volume contribute to electrically conducting and large stone aggregate prevent the electron from transiting. In a word, the variation of output resistance is aroused by the variation of interior structure completely.
基金supported by the National Natural Science Foundation of China under grants Nos. 50906073 and 50973018
文摘The relationship between thermal conductivity and properties of mixing particles is required for quantitative study of heat transfer processes in asphalt-based materials. In this paper, we measured the e？ective ther- mal conductivity of asphalt-based materials with thermal conduction （graphite） and insulation （cenosphere） powders modification. By taking account of the particle shape, volume fraction, the thermal conductivity of filling particles and base asphalt, we present a new differential effective medium formula to predict the thermal conductivity modification in asphalt-based composite. Our theoretical predications are in good agreement with the experiment data. The new model can be applied for predicting the thermal properties of asphalt-based mixture, which is available for most of thermal modification in two-phase composites.
基金the National Key R&D Program of China(2021YFB2601200)the Science and Technology Project of Department of Communication of Zhejiang Province(2021043).
文摘In this study,the regenerative effects of different regenerants on aged SBS-modified asphalt from different perspectives were investigated,including their conventional properties,viscoelastic behavior,creep-related properties,and micromorphology.Base oils composed of different proportions of aromatic and saturated hydrocarbons as well as the styrene-butadiene-styrene(SBS)restorer were used to prepare the regenerants.The results showed that the components of the base oil of the regenerant played a crucial role in determining the characteristics and performance of the recycled SBSmodified asphalt.Regenerants containing a high proportion of aromatics dissolved the hard segment in the SBS restorer,thereby delaying the effect of a reduction in the regenerants on the performance of the aged asphalts at a high temperature.Regenerants containing a high proportion of saturates dissolved the soft segment in the SBS restorer to enhance the lowtemperature performance of the recycled asphalts.In addition,the stress sensitivity of the recycled asphalts increased with the fraction of aromatics in the regenerant.As the aromatic content of the base oil components of the regenerants increased and their saturate content decreased,the state of dispersion of the SBS phase in the recycled SBS-modified asphalts improved.The optimal content of aromatics in the base oil of the regenerants should be set in the range of 33%to 47%to ensure the adequate performance of the recycled asphalts and a high efficiency of the SBS restorer.
基金supported by the TPF-5 (129) Recycled Unbound Materials Pool Fund administered by the Minnesota Department of Transportation and the Recycled Materials Resource Center (RMRC)supported by the U.S. Federal Highway Administration
文摘The objective of this project was to characterize the freeze-thaw properties of recycled concrete(RCA)and asphalt(RAP)as unbound base and to assess how they behaved in the field for nearly 8 years.This paper includes an examination of existing information,laboratory studies of freeze-thaw behavior,and evaluation of data from Mn ROAD field-test sections in a seasonally cold region,i.e.,in Minnesota,USA.Test sections were constructed using recycled materials in the granular base layers at the Mn ROAD test facility.One test section included 100%RAP,another 100%RCA,a third one a 50/50blend of RCA/natural aggregate,and a fourth one only natural aggregate(Class 5)as a control.The stiffness(i.e.,elastic modulus)was monitored during construction and throughout the pavement life by the Minnesota Department of Transportation,along with the variation of temperatures and moisture regimes in the pavement to determine their effects on pavement performance.The resilient modulus of each material was determined by bench-scale testing in accordance with NCHRP 1-28a,as well as by field-scale tests incorporating a falling-weight deflectometer.Specimens were subjected to as many as 20 cycles of freeze-thaw in the laboratory,and the change in their resilient modulus was measured.In the field-test sections constructed with the same materials as the base course,temperature,moisture,and field modulus(from fallingweight deflectometer tests)were monitored seasonally for nearly 8 years.From the temperatures in the base course layer,the number of freeze-thaw cycles experienced in the field was determined for each test section.Inferences were made relative to modulus change versus freeze-thaw cycles.Conclusions were drawn for long-term field performances of the recycled base(RAB)in comparison to natural aggregate.
