Mahmood Al-Obaidi | University of Baghdad (original) (raw)
Papers by Mahmood Al-Obaidi
Nucleation and Atmospheric Aerosols, 2023
Pavement infrastructure is essential and must be protected with limited resources. For decades, i... more Pavement infrastructure is essential and must be protected with limited resources. For decades, industrialized nations have used Pavement Management Systems (PMS) and pavement distress assessment to examine network and project-level pavement conditions. Pavement condition models can anticipate pavement degradation, schedule maintenance, and create multi-year rehabilitation plans based on historical data. Pavement condition surveys are done annually or biannually to calibrate pavement condition models and reduce network maintenance costs. This study highlights road system deficiencies to meet traffic demand, improper systematic methods of maintaining networks, budget constraints for decision makers, deficiencies in road geometrics, poor construction and maintenance practices, the need for proper planning and resource management, and improper planning. The technique comprises a theoretical element of PMS and a review of performance evaluation studies. A PMS lets users export data in an easy-to-understand manner, helping them manage their roadways better. Manual pavement distress surveys need certified raters.
International journal of advances in scientific research and engineering, Jul 1, 2018
Parking is an important part of the transport system and its problems, especially in the capitals... more Parking is an important part of the transport system and its problems, especially in the capitals of countries, are due to dense traffic, business districts, private vehicle use, and the number of population as compared to the area of cities. The purposes of the study are assessing of the efficiency of parking operation including Parking Index (PI), Parking Duration (PD) and Parking Turnovers (PT). The study area included four parks was to be selected in Baghdad city in Iraq based on the advantages of the land use, two in Al-Karkh area and the others in Al-Rusafa area. Parking data were surveyed manually to evaluate parking performance of each park depending on initial questionnaires and previous data.
ACES, 2021
Speed, flow, and density are the most effectiveness traffic parameters. For the study area, all r... more Speed, flow, and density are the most effectiveness traffic parameters. For the study area, all required speed-flow data were collected manually by special team using the necessary survey equipment from 11:00am-6:00pm during one week within different days for each direction of Al-Doura Expressway in Baghdad city. Greenshield Model (GSM) and Greenberg Model (GBM) have been analyzed using EXCEL software to compare the implementation results of the real data. The calibration of regression analysis studies were used and the statistical coefficient of person's correlation (R) and coefficient of determination (R2) were computed. It was found the following: For the direction of Baghdad greater bridge to Al-Rasheed camp, models according to GSM and GBM are us=110.84–0.37k and us=59.24ln(320.72/k) respectively. For the second direction, the models are us=64.04–0.10k and us=11.99ln(2937.5/k) respectively. All models are achieved strong correlation between variables ( between 0.88-0.98, an...
IOP Conference Series: Materials Science and Engineering, 2020
The purposes of the study are assessing the current level of service (LOS) at the 14th-Ramadhan s... more The purposes of the study are assessing the current level of service (LOS) at the 14th-Ramadhan signalized intersection in CBD area of Al-Mansoor district in Baghdad city and increasing the improvement of the traffic operation system by investigating appropriate proposals to increase the traffic capacity of this facility. Data of traffic flow collected using Tally mark method by many observers. Evaluation of the current intersection is to be taken in consideration using HCS Technique (2010), also existing and proposal layouts are displayed using AutoCAD (2017). The results showed that the selected traffic facility are currently suffered from serious lowering in service level causing forced conditions (LOS “F”). Thus, most important considerations should be considered for developing in the LOS by proposing many solutions. In summary, the study is proposed to execute the overpass structure (Grade Separation Bridge) along 14th-Ramadhan street from southbound to northbound directions an...
IOP Conference Series: Materials Science and Engineering, 2019
Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway m... more Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway modes especially at intersections. Traffic management system TMS leads to improve the level of service LOS of the intersections by reducing traffic congestion, delay and time wasted during travel. This research studied the improving of TMS for deactivated Al-Faris Al-Arabi signalized roundabout that considered the important area near city center. Traffic data collected manually by group of engineers during March and April, 2018. Highway Capacity Software HCS2010 used to assess and improve the TMS for current and future forecasted flow. Results showed that roundabout operating on LOS F with a high delay of time and saturation flow. Three solutions proposed to improve the traffic conditions considering of modifying the geometric features with changing and optimizing the timing plan of traffic signals. It showed a highly improving in LOS from F to B, improving saturation flow to less than on...
IOP Conference Series: Materials Science and Engineering, 2020
The purposes of the study are assessing the current level of service (LOS) at the 14 th-Ramadhan ... more The purposes of the study are assessing the current level of service (LOS) at the 14 th-Ramadhan signalized intersection in CBD area of Al-Mansoor district in Baghdad city and increasing the improvement of the traffic operation system by investigating appropriate proposals to increase the traffic capacity of this facility. Data of traffic flow collected using Tally mark method by many observers. Evaluation of the current intersection is to be taken in consideration using HCS Technique (2010), also existing and proposal layouts are displayed using AutoCAD (2017). The results showed that the selected traffic facility are currently suffered from serious lowering in service level causing forced conditions (LOS "F"). Thus, most important considerations should be considered for developing in the LOS by proposing many solutions. In summary, the study is proposed to execute the overpass structure (Grade Separation Bridge) along 14th-Ramadhan street from southbound to northbound directions and vice versa (two lanes in each direction) considering the third proposal (P3). By using HCS2010, the LOS will be changed from F to B assuming that it is expected to continue at higher traffic performance for approximately at least 15 year later
IOP Conference Series: Materials Science and Engineering, 2019
Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway m... more Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway modes especially at intersections. Traffic management system TMS leads to improve the level of service LOS of the intersections by reducing traffic congestion, delay and time wasted during travel. This research studied the improving of TMS for deactivated Al-Faris Al-Arabi signalized roundabout that considered the important area near city center. Traffic data collected manually by group of engineers during March and April, 2018. Highway Capacity Software HCS2010 used to assess and improve the TMS for current and future forecasted flow. Results showed that roundabout operating on LOS F with a high delay of time and saturation flow. Three solutions proposed to improve the traffic conditions considering of modifying the geometric features with changing and optimizing the timing plan of traffic signals. It showed a highly improving in LOS from F to B, improving saturation flow to less than one and reducing in delay time to about 43 times of that at existing conditions. In addition to analysis results, 18 years has been expected to carry the future forecasted data. Finally, architectural model has been achieved to display the pre and post improvement of the study area.
Association of Arab Universities Journal of Engineering Sciences, 2018
The vehicles traffic volume has been increasing rapidly over last years in Iraq especially in cen... more The vehicles traffic volume has been increasing rapidly over last years in Iraq especially in central business districts (CBD) in Baghdad city. The increasing results in growing of congestion level, environmental pollution and time wasted during travel especially at the intersection points. The objectives of the study are evaluating the existing level of service (LOS) at Al-Mansour signalized T-intersection in Baghdad city and improving traffic performance by estimating the best alternatives to increase the traffic capacity of intersection. The traffic volume data were collected manually by group of engineers based on traffic operation of policeman. Assessment of existing intersection at study area is considered using HCS software (2010), also AutoCAD (2017) for display of all existing and proposal layouts. Study results showed that Al-Mansour Intersection currently behaves serious deterioration causing forced conditions LOS "F" with delay of 221.6 s/veh, therefore; instantaneous solutions is to be considered concerning the upgrading of serviceability based on trying many proposals considering the signal timing and geometrical changes with required number of lanes and phases. It showed that a suitable choice is to construct a tunnel (1 lane / direction) along 14-Ramadhan street with actuating two phases giving LOS "B" and delay of 11.1 s/veh.
International Journal of Advances in Scientific Research and Engineering (ijasre), 2018
Parking is an important part of the transport system and its problems, especially in the capitals... more Parking is an important part of the transport system and its problems, especially in the capitals of countries, are due
to dense traffic, business districts, private vehicle use, and the number of population as compared to the area of cities.
The purposes of the study are assessing of the efficiency of parking operation including Parking Index (PI), Parking
Duration (PD) and Parking Turnovers (PT). The study area included four parks was to be selected in Baghdad city in
Iraq based on the advantages of the land use, two in Al-Karkh area and the others in Al-Rusafa area. Parking data
were surveyed manually to evaluate parking performance of each park depending on initial questionnaires and
previous data. Arrival-Departure method is used for evaluating PI, PD, and PT which express the case of parking
efficiency. It showed that PI is 57.00, 97.72, 39.39 and 35.71%, also PD is 41.71, 43.11, 42.67 and 38.88 min, in
addition that PT is 0.82, 1.36, 0.55, 0.55 veh/space for P1, P2, P3 and P4 respectively. The study showed that P1 and
P2 operated below the maximum capacity at PI lower than 50%, it also gave the indication that P2 sometimes
operates with an overcapacity, this may due to bad management of the park in addition to the non-properly use for the
electronic system which controls on entrance gates. Furthermore, it showed that P3 and P4 operated above the
maximum capacity complying with policy 7 of the parking space requirements in parking code guidance 2012 of San
Francisco Department of Transportation.
International Journal of Science and Research (IJSR), 2018
Highways play an important role in the economic and social development of societies; therefore, m... more Highways play an important role in the economic and social development of societies; therefore, many studies are directed
towards modifying pavement properties. In Iraq as well as other countries, pavement surface cracking and rutting are considered as
major problems in roads and airports. The main objective of this work is to evaluate the effect of incorporating method of additives on
Marshall properties of hot mix asphalt (HMA) concrete (wearing surface layer) using different percentages of additive. OAC of (4.7)%
for control mixtures was determined using Marshall mix design. All modified HMA consist of AC of (40-50) penetration grade brought
from Al-Duarah refinery, aggregates obtained from AL-Nibaae quarry with NMAS of (12.5) mm, and mineral filler (Portland cement)
obtained from Tazloja factory, Additive (Fumed Silica (F.S)) its chemical compositions were tested in the laboratories of General
Directorate of Geological survey and Mining. Modified mixtures with (3, 7, 10)% of F.S were prepared based on two methods of
incorporating F.S into the HMA concrete are Stirring and Addition methods. They subdivided into the two groups, the first group refers
to the addition of F.S as a percentage of the total weight of AC (the weight of modified AC stayed constant), The second group refers to
the addition of F.S as a percentage of the total weight of AC (as additional amount) to the weight of AC. Results show that modified
specimens prepared based on stirring method and containing (3% + AC) are the best among all mixtures.
The main objective of this study is to develop predictive models using SPSS software (version 18)... more The main objective of this study is to develop predictive models using SPSS software (version 18) for Marshall Test results of asphalt mixtures compacted by Hammer, Gyratory, and Roller compaction. Bulk density of (2.351) gm/cc, at OAC of (4.7) % was obtained as a benchmark after using Marshall Compactor as laboratory compactive effort with 75-blows. Same density was achieved by Roller and Gyratory Compactors using its mix designed methods. A total of (75) specimens, for Marshall, Gyratory, and Roller Compactors have been prepared, based on OAC of (4.7) % with an additional asphalt contents of more and less than (0.5) % from the optimum value. All specimens have been subjected to Marshall Test. Mathematical models obtained indicated that variation of Marshall Stiffness is based on the variation of air voids. All of these models depend on asphalt cement content too.
Compaction has a significant influence on the performance of asphalt mixtures. Insufficient compa... more Compaction has a significant influence on the performance of asphalt mixtures. Insufficient compaction leads to premature permanent deformation, excessive aging, and moisture damage. The optimum asphalt content was 4.7 % using Marshall Compaction method. Bulk density of (2.351) gm/cc was obtained at OAC with 75 blows of Marshall compactive effort as a benchmark. Same density was achieved using the other two techniques, Gyratory and Roller compactive efforts. Results indicate that (75) blows of Marshall Compaction, are equivalent to (148) gyrations in Gyratory Compactor with pressure of (600) KPa and angle of gyration of (1.25°), and they are also equivalent to (56) cycles in Roller Compactor at load (5) KN and vibration with air supply of (10) bar, to obtain the same density. A total of 162 Marshal Size specimens were prepared, using Marshall, and Gyratory Compaction techniques, based on OAC of 4.7 % with additional asphalt contents of 0.5% above and below the optimum value. Twelve slabs of (40 x 30 x 6.35) cm were constructed using Roller Compactor and (6) core specimens were obtained for each slab. All specimens were subjected to the Indirect tensile strength (ITS) at 25ºC, 40ºC, and 60ºC, temperature susceptibility (TS), and tensile strength ratio (TSR) test for the three methods of compaction. The main objective of this study is to evaluate impact on the tensile and temperature susceptibility of compacted hot mix asphalt concrete (HMA) when using three methods of compaction to achieve same density.
Shear strength of asphalt concrete is considered as a good predictor for rutting potential. If th... more Shear strength of asphalt concrete is considered as a good predictor for rutting potential. If the material cannot resist the load repetitions of vehicles, it flows laterally due to shear forces and causes rut formation. Compaction has a significant influence on the performance of asphalt mixtures, however modeling the field compaction in the laboratory is essential in understanding such behavior. In this work, the impact of various compaction modes on shear strength of asphalt concrete was modeled. Bulk density of (2.351) gm/cc was obtained at 4.7% optimum asphalt content OAC with 75 blows of Marshall compactive effort as a benchmark. Same density was achieved using the other two techniques, Gyratory and Roller compactive efforts. Results indicate that (75) blows of Marshall Compaction, are equivalent to (148) gyrations in Gyratory Compactor with pressure of (600) KPa and angle of gyration of (1.25°), and they are also equivalent to (56) cycles in Roller Compactor at load (5) KN and vibration with air supply of (10) bar, to obtain the same density. Specimens were prepared, using Marshall, and Gyratory Compaction techniques. Slabs specimens of (40 x 30 x 6.35) cm were constructed using Roller Compactor and (6) core specimens were obtained for each slab. Specimens prepared by the three-compaction method were subjected to the double punch shear test. The main objective of this study is to model the impact of using three methods of compaction to achieve same density on the shear strength of hot mix asphalt concrete (HMA).
Nucleation and Atmospheric Aerosols, 2023
Pavement infrastructure is essential and must be protected with limited resources. For decades, i... more Pavement infrastructure is essential and must be protected with limited resources. For decades, industrialized nations have used Pavement Management Systems (PMS) and pavement distress assessment to examine network and project-level pavement conditions. Pavement condition models can anticipate pavement degradation, schedule maintenance, and create multi-year rehabilitation plans based on historical data. Pavement condition surveys are done annually or biannually to calibrate pavement condition models and reduce network maintenance costs. This study highlights road system deficiencies to meet traffic demand, improper systematic methods of maintaining networks, budget constraints for decision makers, deficiencies in road geometrics, poor construction and maintenance practices, the need for proper planning and resource management, and improper planning. The technique comprises a theoretical element of PMS and a review of performance evaluation studies. A PMS lets users export data in an easy-to-understand manner, helping them manage their roadways better. Manual pavement distress surveys need certified raters.
International journal of advances in scientific research and engineering, Jul 1, 2018
Parking is an important part of the transport system and its problems, especially in the capitals... more Parking is an important part of the transport system and its problems, especially in the capitals of countries, are due to dense traffic, business districts, private vehicle use, and the number of population as compared to the area of cities. The purposes of the study are assessing of the efficiency of parking operation including Parking Index (PI), Parking Duration (PD) and Parking Turnovers (PT). The study area included four parks was to be selected in Baghdad city in Iraq based on the advantages of the land use, two in Al-Karkh area and the others in Al-Rusafa area. Parking data were surveyed manually to evaluate parking performance of each park depending on initial questionnaires and previous data.
ACES, 2021
Speed, flow, and density are the most effectiveness traffic parameters. For the study area, all r... more Speed, flow, and density are the most effectiveness traffic parameters. For the study area, all required speed-flow data were collected manually by special team using the necessary survey equipment from 11:00am-6:00pm during one week within different days for each direction of Al-Doura Expressway in Baghdad city. Greenshield Model (GSM) and Greenberg Model (GBM) have been analyzed using EXCEL software to compare the implementation results of the real data. The calibration of regression analysis studies were used and the statistical coefficient of person's correlation (R) and coefficient of determination (R2) were computed. It was found the following: For the direction of Baghdad greater bridge to Al-Rasheed camp, models according to GSM and GBM are us=110.84–0.37k and us=59.24ln(320.72/k) respectively. For the second direction, the models are us=64.04–0.10k and us=11.99ln(2937.5/k) respectively. All models are achieved strong correlation between variables ( between 0.88-0.98, an...
IOP Conference Series: Materials Science and Engineering, 2020
The purposes of the study are assessing the current level of service (LOS) at the 14th-Ramadhan s... more The purposes of the study are assessing the current level of service (LOS) at the 14th-Ramadhan signalized intersection in CBD area of Al-Mansoor district in Baghdad city and increasing the improvement of the traffic operation system by investigating appropriate proposals to increase the traffic capacity of this facility. Data of traffic flow collected using Tally mark method by many observers. Evaluation of the current intersection is to be taken in consideration using HCS Technique (2010), also existing and proposal layouts are displayed using AutoCAD (2017). The results showed that the selected traffic facility are currently suffered from serious lowering in service level causing forced conditions (LOS “F”). Thus, most important considerations should be considered for developing in the LOS by proposing many solutions. In summary, the study is proposed to execute the overpass structure (Grade Separation Bridge) along 14th-Ramadhan street from southbound to northbound directions an...
IOP Conference Series: Materials Science and Engineering, 2019
Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway m... more Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway modes especially at intersections. Traffic management system TMS leads to improve the level of service LOS of the intersections by reducing traffic congestion, delay and time wasted during travel. This research studied the improving of TMS for deactivated Al-Faris Al-Arabi signalized roundabout that considered the important area near city center. Traffic data collected manually by group of engineers during March and April, 2018. Highway Capacity Software HCS2010 used to assess and improve the TMS for current and future forecasted flow. Results showed that roundabout operating on LOS F with a high delay of time and saturation flow. Three solutions proposed to improve the traffic conditions considering of modifying the geometric features with changing and optimizing the timing plan of traffic signals. It showed a highly improving in LOS from F to B, improving saturation flow to less than on...
IOP Conference Series: Materials Science and Engineering, 2020
The purposes of the study are assessing the current level of service (LOS) at the 14 th-Ramadhan ... more The purposes of the study are assessing the current level of service (LOS) at the 14 th-Ramadhan signalized intersection in CBD area of Al-Mansoor district in Baghdad city and increasing the improvement of the traffic operation system by investigating appropriate proposals to increase the traffic capacity of this facility. Data of traffic flow collected using Tally mark method by many observers. Evaluation of the current intersection is to be taken in consideration using HCS Technique (2010), also existing and proposal layouts are displayed using AutoCAD (2017). The results showed that the selected traffic facility are currently suffered from serious lowering in service level causing forced conditions (LOS "F"). Thus, most important considerations should be considered for developing in the LOS by proposing many solutions. In summary, the study is proposed to execute the overpass structure (Grade Separation Bridge) along 14th-Ramadhan street from southbound to northbound directions and vice versa (two lanes in each direction) considering the third proposal (P3). By using HCS2010, the LOS will be changed from F to B assuming that it is expected to continue at higher traffic performance for approximately at least 15 year later
IOP Conference Series: Materials Science and Engineering, 2019
Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway m... more Baghdad city, the capital of Iraq has mainly suffered from influences of transportation highway modes especially at intersections. Traffic management system TMS leads to improve the level of service LOS of the intersections by reducing traffic congestion, delay and time wasted during travel. This research studied the improving of TMS for deactivated Al-Faris Al-Arabi signalized roundabout that considered the important area near city center. Traffic data collected manually by group of engineers during March and April, 2018. Highway Capacity Software HCS2010 used to assess and improve the TMS for current and future forecasted flow. Results showed that roundabout operating on LOS F with a high delay of time and saturation flow. Three solutions proposed to improve the traffic conditions considering of modifying the geometric features with changing and optimizing the timing plan of traffic signals. It showed a highly improving in LOS from F to B, improving saturation flow to less than one and reducing in delay time to about 43 times of that at existing conditions. In addition to analysis results, 18 years has been expected to carry the future forecasted data. Finally, architectural model has been achieved to display the pre and post improvement of the study area.
Association of Arab Universities Journal of Engineering Sciences, 2018
The vehicles traffic volume has been increasing rapidly over last years in Iraq especially in cen... more The vehicles traffic volume has been increasing rapidly over last years in Iraq especially in central business districts (CBD) in Baghdad city. The increasing results in growing of congestion level, environmental pollution and time wasted during travel especially at the intersection points. The objectives of the study are evaluating the existing level of service (LOS) at Al-Mansour signalized T-intersection in Baghdad city and improving traffic performance by estimating the best alternatives to increase the traffic capacity of intersection. The traffic volume data were collected manually by group of engineers based on traffic operation of policeman. Assessment of existing intersection at study area is considered using HCS software (2010), also AutoCAD (2017) for display of all existing and proposal layouts. Study results showed that Al-Mansour Intersection currently behaves serious deterioration causing forced conditions LOS "F" with delay of 221.6 s/veh, therefore; instantaneous solutions is to be considered concerning the upgrading of serviceability based on trying many proposals considering the signal timing and geometrical changes with required number of lanes and phases. It showed that a suitable choice is to construct a tunnel (1 lane / direction) along 14-Ramadhan street with actuating two phases giving LOS "B" and delay of 11.1 s/veh.
International Journal of Advances in Scientific Research and Engineering (ijasre), 2018
Parking is an important part of the transport system and its problems, especially in the capitals... more Parking is an important part of the transport system and its problems, especially in the capitals of countries, are due
to dense traffic, business districts, private vehicle use, and the number of population as compared to the area of cities.
The purposes of the study are assessing of the efficiency of parking operation including Parking Index (PI), Parking
Duration (PD) and Parking Turnovers (PT). The study area included four parks was to be selected in Baghdad city in
Iraq based on the advantages of the land use, two in Al-Karkh area and the others in Al-Rusafa area. Parking data
were surveyed manually to evaluate parking performance of each park depending on initial questionnaires and
previous data. Arrival-Departure method is used for evaluating PI, PD, and PT which express the case of parking
efficiency. It showed that PI is 57.00, 97.72, 39.39 and 35.71%, also PD is 41.71, 43.11, 42.67 and 38.88 min, in
addition that PT is 0.82, 1.36, 0.55, 0.55 veh/space for P1, P2, P3 and P4 respectively. The study showed that P1 and
P2 operated below the maximum capacity at PI lower than 50%, it also gave the indication that P2 sometimes
operates with an overcapacity, this may due to bad management of the park in addition to the non-properly use for the
electronic system which controls on entrance gates. Furthermore, it showed that P3 and P4 operated above the
maximum capacity complying with policy 7 of the parking space requirements in parking code guidance 2012 of San
Francisco Department of Transportation.
International Journal of Science and Research (IJSR), 2018
Highways play an important role in the economic and social development of societies; therefore, m... more Highways play an important role in the economic and social development of societies; therefore, many studies are directed
towards modifying pavement properties. In Iraq as well as other countries, pavement surface cracking and rutting are considered as
major problems in roads and airports. The main objective of this work is to evaluate the effect of incorporating method of additives on
Marshall properties of hot mix asphalt (HMA) concrete (wearing surface layer) using different percentages of additive. OAC of (4.7)%
for control mixtures was determined using Marshall mix design. All modified HMA consist of AC of (40-50) penetration grade brought
from Al-Duarah refinery, aggregates obtained from AL-Nibaae quarry with NMAS of (12.5) mm, and mineral filler (Portland cement)
obtained from Tazloja factory, Additive (Fumed Silica (F.S)) its chemical compositions were tested in the laboratories of General
Directorate of Geological survey and Mining. Modified mixtures with (3, 7, 10)% of F.S were prepared based on two methods of
incorporating F.S into the HMA concrete are Stirring and Addition methods. They subdivided into the two groups, the first group refers
to the addition of F.S as a percentage of the total weight of AC (the weight of modified AC stayed constant), The second group refers to
the addition of F.S as a percentage of the total weight of AC (as additional amount) to the weight of AC. Results show that modified
specimens prepared based on stirring method and containing (3% + AC) are the best among all mixtures.
The main objective of this study is to develop predictive models using SPSS software (version 18)... more The main objective of this study is to develop predictive models using SPSS software (version 18) for Marshall Test results of asphalt mixtures compacted by Hammer, Gyratory, and Roller compaction. Bulk density of (2.351) gm/cc, at OAC of (4.7) % was obtained as a benchmark after using Marshall Compactor as laboratory compactive effort with 75-blows. Same density was achieved by Roller and Gyratory Compactors using its mix designed methods. A total of (75) specimens, for Marshall, Gyratory, and Roller Compactors have been prepared, based on OAC of (4.7) % with an additional asphalt contents of more and less than (0.5) % from the optimum value. All specimens have been subjected to Marshall Test. Mathematical models obtained indicated that variation of Marshall Stiffness is based on the variation of air voids. All of these models depend on asphalt cement content too.
Compaction has a significant influence on the performance of asphalt mixtures. Insufficient compa... more Compaction has a significant influence on the performance of asphalt mixtures. Insufficient compaction leads to premature permanent deformation, excessive aging, and moisture damage. The optimum asphalt content was 4.7 % using Marshall Compaction method. Bulk density of (2.351) gm/cc was obtained at OAC with 75 blows of Marshall compactive effort as a benchmark. Same density was achieved using the other two techniques, Gyratory and Roller compactive efforts. Results indicate that (75) blows of Marshall Compaction, are equivalent to (148) gyrations in Gyratory Compactor with pressure of (600) KPa and angle of gyration of (1.25°), and they are also equivalent to (56) cycles in Roller Compactor at load (5) KN and vibration with air supply of (10) bar, to obtain the same density. A total of 162 Marshal Size specimens were prepared, using Marshall, and Gyratory Compaction techniques, based on OAC of 4.7 % with additional asphalt contents of 0.5% above and below the optimum value. Twelve slabs of (40 x 30 x 6.35) cm were constructed using Roller Compactor and (6) core specimens were obtained for each slab. All specimens were subjected to the Indirect tensile strength (ITS) at 25ºC, 40ºC, and 60ºC, temperature susceptibility (TS), and tensile strength ratio (TSR) test for the three methods of compaction. The main objective of this study is to evaluate impact on the tensile and temperature susceptibility of compacted hot mix asphalt concrete (HMA) when using three methods of compaction to achieve same density.
Shear strength of asphalt concrete is considered as a good predictor for rutting potential. If th... more Shear strength of asphalt concrete is considered as a good predictor for rutting potential. If the material cannot resist the load repetitions of vehicles, it flows laterally due to shear forces and causes rut formation. Compaction has a significant influence on the performance of asphalt mixtures, however modeling the field compaction in the laboratory is essential in understanding such behavior. In this work, the impact of various compaction modes on shear strength of asphalt concrete was modeled. Bulk density of (2.351) gm/cc was obtained at 4.7% optimum asphalt content OAC with 75 blows of Marshall compactive effort as a benchmark. Same density was achieved using the other two techniques, Gyratory and Roller compactive efforts. Results indicate that (75) blows of Marshall Compaction, are equivalent to (148) gyrations in Gyratory Compactor with pressure of (600) KPa and angle of gyration of (1.25°), and they are also equivalent to (56) cycles in Roller Compactor at load (5) KN and vibration with air supply of (10) bar, to obtain the same density. Specimens were prepared, using Marshall, and Gyratory Compaction techniques. Slabs specimens of (40 x 30 x 6.35) cm were constructed using Roller Compactor and (6) core specimens were obtained for each slab. Specimens prepared by the three-compaction method were subjected to the double punch shear test. The main objective of this study is to model the impact of using three methods of compaction to achieve same density on the shear strength of hot mix asphalt concrete (HMA).