Asphalt-rubber pavements often become dam-aged in high-temperature regions and appear rutted or wavy, and experience slippage. To improve the high-temperature performance of the asphalt-rubber mixture, technical measu...Asphalt-rubber pavements often become dam-aged in high-temperature regions and appear rutted or wavy, and experience slippage. To improve the high-temperature performance of the asphalt-rubber mixture, technical measurements, such as, the optimal adjustment of gradation, technique of composite modification, and control of compaction were investigated. An optimal adjustment of aggregate gradation based on stone matrix asphalt improves the high-temperature stability of the asphaltrubber mixture significantly. Through composite modifi- cation, the effect of asphalt-rubber modification was enhanced, and the dynamic stability and relative defor- mation indices of the asphalt-rubber mixture were improved significantly. Furthermore, compaction parame- ters had a significant influence on the high-temperature stability of the asphalt-rubber mixture. The rolling times for compacting the asphalt-rubber mixture should be controlled to within 18-20 round-trips at a molding temperature at 180℃; if the rolling time is a 12 round-trip, the compaction temperature of the asphalt-rubber mixture should be controlled between 180 and 190℃.展开更多
Design method for large stone porous asphalt mixtures （LSPM） was analyzed to avoid the early distresses of semi-rigid asphalt pavements. Based on stone-to-stone skeleton structure concept, processes of LSPM gradatio...Design method for large stone porous asphalt mixtures （LSPM） was analyzed to avoid the early distresses of semi-rigid asphalt pavements. Based on stone-to-stone skeleton structure concept, processes of LSPM gradation design was given. The gradation composite design for LSPM shows that the LSPM nominal maximum size （ N MS） should be larger than 26.5 mm, and the NMS sieve passing percentage should be greater than 50%. Through experiments and calculations on the volume properties of the aggregate, the range of aggregate gradation curve of LSPM was given. In terms of asphalt binder＇s normalized test results, MAC-70 and SBS modified asphalt were selected as the asphalt binders. The applicability of large scale Marshall Method and gyratory compaction method to shape specimens was investigated. Based on the asphalt mixture performance evaluation, the optimum asphalt content range （3.1%-3.6%）, the bitumen film＇s thickness range （13-16 μm） and the air void range （13%-18 %） were recommended. Finally, LSPM was tested by the laboratory performance tests including rutting resistance test, fatigue test and water stability test. The theoretic and practical analysis shows that LSPM has a good performance on water permeability, rutting resistance and reflection crack resistance.展开更多
The use of steel slag,which is a by-product of the steel manufacture,in the construction of asphalt pavement would contribute to waste reduction and environment protection.Using rubber asphalt at the same time can imp...The use of steel slag,which is a by-product of the steel manufacture,in the construction of asphalt pavement would contribute to waste reduction and environment protection.Using rubber asphalt at the same time can improve the performance of asphalt mixture.This study investigates the influence of steel slag content on the road performance,thermal conductivity and outdoor temperature distribution of steel slag rubber asphalt mixtures(SSRAM),and calculates the cumulative stress in surface layer.At a certain range of concentration,the steel slag additive improved the deformation resistance and low-temperature cracking resistance of the mixtures.The SSRAM with 40%steel slag content has the best deformation resistance while SSRAM with 60%steel slag content performed well in low-temperature cracking resistance.The thermal conductivity of the SSRAM with different steel slag content(0%,20%,40%,60%,80%,and 100%)was 1.994,2.188,2.239,2.255,2.288,and 2.295 W/(m·K),respectively.Measurements of the outdoor temperature distribution further confirmed that steel slag increased the thermal conductivity of the mixtures,thereby increasing the cumulative temperature difference between the top and bottom layers.The temperature stress and temperature-stress ratio of the SSRAM with 40%steel slag were 0.43 MPa and 0.24,while the SSRAM with 100%steel slag were 0.58 MPa and 0.36.The stress and stress ratio were much higher in the SSRAM with 100%steel slag than in the specimen with 40%steel slag.Accordingly,the maximum accumulated temperature stress aggrandized and caused early temperature cracks in the surface layer.The optimum content of steel slag was 40%.展开更多
To evaluate the effects of Crumb Rubber Modifiers (CRMS) on basic engineering properties (i.e. Marshall, tensile strength, and compressive strength) of stone matrix asphalt mixtures, the ASTM testing and procedures we...To evaluate the effects of Crumb Rubber Modifiers (CRMS) on basic engineering properties (i.e. Marshall, tensile strength, and compressive strength) of stone matrix asphalt mixtures, the ASTM testing and procedures were employed. Results of the evaluation were used to quantify the effect of CRM source and CRM content on engineering properties at testing temperatures of 25 ℃ and 60 ℃. Statistical models were developed, which represent the nature of effects on performance-related properties of stone matrix asphalt mixtures.展开更多
We have used a unique process to develop the first successful anion rubber modified asphalt mixture.Rubber and asphalt are used in equal proportions in the mix.Compared with conventional asphalt,the anion rubber modif...We have used a unique process to develop the first successful anion rubber modified asphalt mixture.Rubber and asphalt are used in equal proportions in the mix.Compared with conventional asphalt,the anion rubber modified asphalt show better pavement performance,and fully met the relevant specifications.The dynamic stability and failure strain indicators are better than those of SBS modified asphalt.Compared with traditional rubber modified asphalt,the amount of waste tires incorporated into this new rubber modified asphalt is much greater;the new asphalt also improved the air quality near the road,thus providing great economic and social benefits.展开更多
文摘Asphalt-rubber pavements often become dam-aged in high-temperature regions and appear rutted or wavy, and experience slippage. To improve the high-temperature performance of the asphalt-rubber mixture, technical measurements, such as, the optimal adjustment of gradation, technique of composite modification, and control of compaction were investigated. An optimal adjustment of aggregate gradation based on stone matrix asphalt improves the high-temperature stability of the asphaltrubber mixture significantly. Through composite modifi- cation, the effect of asphalt-rubber modification was enhanced, and the dynamic stability and relative defor- mation indices of the asphalt-rubber mixture were improved significantly. Furthermore, compaction parame- ters had a significant influence on the high-temperature stability of the asphalt-rubber mixture. The rolling times for compacting the asphalt-rubber mixture should be controlled to within 18-20 round-trips at a molding temperature at 180℃; if the rolling time is a 12 round-trip, the compaction temperature of the asphalt-rubber mixture should be controlled between 180 and 190℃.
文摘Design method for large stone porous asphalt mixtures （LSPM） was analyzed to avoid the early distresses of semi-rigid asphalt pavements. Based on stone-to-stone skeleton structure concept, processes of LSPM gradation design was given. The gradation composite design for LSPM shows that the LSPM nominal maximum size （ N MS） should be larger than 26.5 mm, and the NMS sieve passing percentage should be greater than 50%. Through experiments and calculations on the volume properties of the aggregate, the range of aggregate gradation curve of LSPM was given. In terms of asphalt binder＇s normalized test results, MAC-70 and SBS modified asphalt were selected as the asphalt binders. The applicability of large scale Marshall Method and gyratory compaction method to shape specimens was investigated. Based on the asphalt mixture performance evaluation, the optimum asphalt content range （3.1%-3.6%）, the bitumen film＇s thickness range （13-16 μm） and the air void range （13%-18 %） were recommended. Finally, LSPM was tested by the laboratory performance tests including rutting resistance test, fatigue test and water stability test. The theoretic and practical analysis shows that LSPM has a good performance on water permeability, rutting resistance and reflection crack resistance.
基金This research was funded by the Department of Transportation of Hebei Province(Grant No.TH1-202019).
文摘The use of steel slag,which is a by-product of the steel manufacture,in the construction of asphalt pavement would contribute to waste reduction and environment protection.Using rubber asphalt at the same time can improve the performance of asphalt mixture.This study investigates the influence of steel slag content on the road performance,thermal conductivity and outdoor temperature distribution of steel slag rubber asphalt mixtures(SSRAM),and calculates the cumulative stress in surface layer.At a certain range of concentration,the steel slag additive improved the deformation resistance and low-temperature cracking resistance of the mixtures.The SSRAM with 40%steel slag content has the best deformation resistance while SSRAM with 60%steel slag content performed well in low-temperature cracking resistance.The thermal conductivity of the SSRAM with different steel slag content(0%,20%,40%,60%,80%,and 100%)was 1.994,2.188,2.239,2.255,2.288,and 2.295 W/(m·K),respectively.Measurements of the outdoor temperature distribution further confirmed that steel slag increased the thermal conductivity of the mixtures,thereby increasing the cumulative temperature difference between the top and bottom layers.The temperature stress and temperature-stress ratio of the SSRAM with 40%steel slag were 0.43 MPa and 0.24,while the SSRAM with 100%steel slag were 0.58 MPa and 0.36.The stress and stress ratio were much higher in the SSRAM with 100%steel slag than in the specimen with 40%steel slag.Accordingly,the maximum accumulated temperature stress aggrandized and caused early temperature cracks in the surface layer.The optimum content of steel slag was 40%.
文摘To evaluate the effects of Crumb Rubber Modifiers (CRMS) on basic engineering properties (i.e. Marshall, tensile strength, and compressive strength) of stone matrix asphalt mixtures, the ASTM testing and procedures were employed. Results of the evaluation were used to quantify the effect of CRM source and CRM content on engineering properties at testing temperatures of 25 ℃ and 60 ℃. Statistical models were developed, which represent the nature of effects on performance-related properties of stone matrix asphalt mixtures.
基金supported by the National"Eleventh Five-Year"Technology Support Program Foundation(2006BAD10B08)the Natural Science Foundation of Hebei Province(E2009000448)
文摘We have used a unique process to develop the first successful anion rubber modified asphalt mixture.Rubber and asphalt are used in equal proportions in the mix.Compared with conventional asphalt,the anion rubber modified asphalt show better pavement performance,and fully met the relevant specifications.The dynamic stability and failure strain indicators are better than those of SBS modified asphalt.Compared with traditional rubber modified asphalt,the amount of waste tires incorporated into this new rubber modified asphalt is much greater;the new asphalt also improved the air quality near the road,thus providing great economic and social benefits.
