Rawid Khan

Laboratory Mix Design of Asphalt Mixture Containing Reclaimed Material

This paper presents a study on the production of asphalt test specimens in the laboratory containing reclaimed asphalt. The mixtures considered were stone mastic asphalt concrete mixtures containing up to 30% of reclaimed asphalt. Specimens were compacted to the reference density obtained from the Marshall mix design. Gyration compaction method was used for preparing specimens for the experimental programme, while coring and cutting methods and X-ray computed tomography (CT) were used to investigate the change in properties within the specimens and to validate the selected methodology. The study concluded that gyratory compaction is suitable to produce homogeneous test specimens also for mixtures containing high amount of reclaimed asphalt. Nevertheless, preliminary trials for each material are mandatory, as well as final coring and trimming of the specimens due to side effects.

Reclaimed asphalt test specimen preparation assisted by image analysis

This paper presents a laboratory investigation aimed at establishing a protocol for the production of homogeneous asphalt mixtures test specimens, incorporating reclaimed asphalt by using a gyratory compactor with coring and trimming works. Stone mastic asphalt specimens were compacted at the previously identified target densities with the final aim of obtaining specimens with a fixed and homogeneous air void distribution. A microstructural study was conducted to characterize the homogeneity in the air void distribution using X-ray computed tomography (CT) combined with image analysis techniques. The study concluded that the gyratory compactor is suitable for producing homogeneous test specimens for the specified mixtures and a set of detailed procedures has been proposed for the production of the compacted specimens and to perform the microstructural study.

The study of the effect of internal structure on permeability of porous asphalt

X-ray computed tomography (CT) and laboratory permeability techniques were applied to study the internal properties of porous asphalt mixture. Specimens containing aggregate of different gradations and of different mineral compositions were prepared in the laboratory. The air voids of all the specimens were determined in the laboratory and the specimens were then scanned in X-ray CT. The same samples were then tested for laboratory permeability. The active air voids and contact points of aggregate with nearby aggregate particles were determined from X-ray CT images. The laboratory permeability test results were found in comparison with X-ray CT values of voids’ internal connectivity. A comparatively high permeability value was observed for porous asphalt with maximum aggregate size irrespective of its mineral composition. The size of air voids and volume of active (connected) air voids were also found high for mixtures made up of large aggregate size. The difference in mineral composition of aggregate was found to have considerably less effect on permeability of porous asphalt.

STABILITY ANALYSIS OF SOIL SLOPE IN SWABI, PAKISTAN

In this study, slope stability analysis for a particular type of soil in Swabi area was carried out using the method of slices. Gravity load and seismic load were considered in the stability analysis. SLOPE/W and SIGMA/W software of Geo studio package were used for analysis under both dry and completely saturated conditions. Pseudo-static approach was used for the seismic stability analysis. The peak ground acceleration value for stability analysis was obtained from the seismic hazard analysis. Two soil slope conditions were considered, and one was found in critical condition. Retaining wall, Soil nails and ground anchors were assumed in the analysis for stability of slope with critical condition. Peak ground acceleration value of 0.235g is determined with site specific deterministic seismic hazard assessment approach. The maximum displacement in the soil slopes with retaining wall, soil nails, and ground anchors are 0.0220, 0.01665 and 0.01529 feet respectively. Results showed that using ground anchors have a factor of safety 1.165 and both the horizontal and vertical deformation values are within the limit. Based on results, ground anchors technique was found to be a suitable method for slope stability in Swabi.

The Study of Bus Rapid Transit (BRT) System at University Road Peshawar, Pakistan

The paper is part of an ongoing research project on traffic management strategies for Peshawar Pakistan. A survey of all the existing public transport stops on University Road Peshawar conducted for identification of bus lane. Peak hour demand was calculated in terms of actual Passengers per hour per direction (Pphpd)along the entire corridor which acts a warrant test for the provision of a separate lane for public transport vehicles in Bus Rapid Transit (BRT) System. Saturation Levelsand Dwell Times (sec)at every stop both for busses and for wagons usingfrequency, clearance time, amount of boarding and alighting passengers and journey time of existing public transport system were analyzed.From data analysis, theSaturation Levels and Dwell Times at every stop were found higher than the recommended values mainly because of the obstruction due to private vehicles in front of public transport vehicles,a comparatively high percentage of private vehicles with respect to public transport vehicles and the prolong stay of drivers atbus stops. The Saturation Levels and Dwell Times (sec) for the proposed BRT system was re-analyzed. Finally, result of the proposed BRT system was incorporated in S-Paramics software to develop a public transport model.

MOISTURE DAMAGE IN ASPHALT MIXTURES FROM SATS TEST AND X-RAY CT

This study investigated damage in asphalt due to moisture by using the modified SATS (saturation aging tensile stiffness) test along with image analysis. Specimens made from granite aggregate and limestone aggregate and of high grade (hard) bitumen were tested in the modified SATS test. The samples were scanned within an X-ray CT before the testing using SATS, after the initial saturation and at the completion of SATS test. Bitumen was extracted from tested specimens and scanned separately in a high resolution Nanotom. The extracted bitumen was tested in a DSR for Shear properties. The specimens made from granite (acidic) and limestone (basic) aggregate were found to have similar permeability and was high for specimens having high design void content. Specimens made from basic aggregate had higher stiffness value than the specimens made from acidic aggregate. The Master curve of aged binder is different to that of virgin binder (bitumen). The microstructure of binder observed was different for aged and virgin binder.

LABORATORY MIX DESIGN OF ASPHALT CONTAINING RE-CLAIMED MATERIAL

This paper presents a study on the production of asphalt test specimens in the laboratory containing reclaimed asphalt. The mixtures considered were stone mastic asphalt concrete mixtures containing up to 30% of reclaimed asphalt. Specimens were compacted to the reference density obtained from the Marshall mix design. Gyration compaction method was used for preparing specimens for the experimental programme, while coring and cutting methods and X-ray computed tomography were used to investigate the change in properties within the specimens and to validate the selected methodology. The study concluded that gyratory compaction is suitable to produce homogeneous test specimens also for mixtures containing high amount of reclaimed asphalt. Nevertheless, preliminary trials for each material are mandatory, as well as final coring and trimming of the specimens due to side effects.

Feasibility Study of Traffic Signals at Intersections in Peshawar, Pakistan

The paper is part of an ongoing research project on traffic management strategies for Peshawar Pakistan. Traffic data collected and warrant tests checked at selected intersections. Peak hour vehicular volume warrant test selected and performed at intersections. Signal timing capacity and delay analysis performed and level of service determined for selected intersection. It was found that “for the same width of the road” the delay and level of service is different at different locations and the corresponding signal time is also different. Some data also analysed in 3D micro simulation.

Microstructural study of asphalt mixture containing reclaimed material

In this paper mixing of reclaimed material with virgin asphalt material has been studied non-destructively. Specimens prepared with virgin asphalt mix and with asphalt mix containing reclaimed material were scanned in X-ray Computed tomography (CT). The obtained Images were analysed for particles and pores (air voids) distribution. All the specimens were also tested in compression test and X-ray scanned while testing. It was found that distribution of reclaimed is not uniform through the samples. There is no considerable effect of increasing the mixing time on particles’ distribution. Similar trend of increase in air voids (cracks) with the increase in load was found for both virgin mix and for asphalt mix containing reclaimed material. Only at failure the increase in voids was found higher for specimens containing reclaimed material.