The use of planetary regolith can be explored via the utilization of simulants. The existing Mart... more The use of planetary regolith can be explored via the utilization of simulants. The existing Martian simulants have differences due to varying source materials and design parameters. Additional simulants are needed because the few available simulants do not replicate the compositional diversity of Martian regolith. This study discusses the development of a low-cost construction simulant of Mars. The area of Winder Nai in Pakistan was selected for field sampling of basalt because of local availability and easy access. The dust was produced from rock samples through mechanical crushing and grinding. The physical properties, composition, mineralogy, and surface morphology were evaluated via geotechnical tests, Energy Dispersive X-ray (EDX) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The designed simulant has a well-graded particle size distribution with a particle density and bulk density of 2.58 g/cm3 and 1.16 g/cm3, respectively. The elemental composition of Winder Nai Mars Simulant (WNMS) is within ±5 wt% of the Rocknest and the average Martian regolith composition except for SO3. For SiO2, Al2O3, and Fe2O3, WNMS has a good match with the Martian regolith. The content of CaO and TiO2 in WNMS is higher than, and content of MgO is lower than, the average Martian values. The rock can be classified as basalt based on the Total Alkali Silica (TAS) diagram. XRD spectrum indicates the occurrence of plagioclase and pyroxene as the main signature minerals of basalt. The particle morphology of WNMS is angular to subangular, and the simulant indicates the presence of 3.8 wt% highly paramagnetic particles. The volatile loss is 0.25 wt% at 100 °C, 1.73 wt% at 500 °C, and 3.05 wt% at 950 °C. The composition of WNMS, basaltic mineralogy, morphology, magnetic properties, and volatile content are comparable with MMS-2 and a few other simulants.
There has been an increase in plastic production during the past decades, yet the recycling of pl... more There has been an increase in plastic production during the past decades, yet the recycling of plastic remains relatively low. Incorporating plastic in concrete can mitigate environmental pollution. The use of waste polyethylene terephthalate (PET) bottles as an aggregate weakens properties of concrete. An alternative is to use PET bottles as a binder in the mortar. The PET binder mixed with sand results in weak mortar. Marble and iron slag can enhance PET mortar properties by preventing alkali reactions. This study examines the mechanical and durability properties of PET mortar with different mixes. The mixes were prepared as plastic and marble (PM); plastic and iron slag (PI); plastic, sand, and marble (PSM); plastic, iron slag, and marble (PIM); and plastic, sand, and iron slag (PSI). PM with 30–45% plastic content had increased compressive and flexural strength up to 35.73% and 20.21%, respectively. PI with 30–35% plastic content showed strength improvements up to 29.19% and 5.02%, respectively. However, at 45% plastic content, strength decreased by 8.8% and 27.90%. PSM, PIM, and PSI specimens had nearly double the strength of ordinary Portland cement (OPC) mortar. The durability of PET mortar in chemical solutions, mainly 5% HCl and 20% NaOH, indicate that mass decreased after 3, 7, and 28 days. All specimens showed good resistance to HCl and NaCl solutions compared to OPC mortar. However, its resistance to NaOH is low compared to OPC mortar. PET mortar without cement showed higher strength and durability than cement mortar, making it suitable for paver tiles, drainage systems, and roads.
Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences, 2023
Pedestrians’ safe mobility at intersections is associated with the facilities provided at the cro... more Pedestrians’ safe mobility at intersections is associated with the facilities provided at the crossings. Lahore is one of the most populous cities in Pakistan. Too many road accidents occur daily at various areas of Lahore in which pedestrian-vehicle collision has a major ratio. To reduce the pedestrian-vehicle collisions, pedestrian signals are installed at major intersections of Lahore city. This paper examines the relationship between pedestrian signals and Level of Service (LOS), with a focus on enhancing awareness of pedestrian signal operation and investigates the impact of pedestrian signals on the LOS of intersections in Lahore in terms of pedestrian movement. Research shows that the poor level of awareness about how pedestrian signals work contributes to the inadequate level of service of intersections in terms of pedestrian movement. The results also provide valuable insights for policymakers and practitioners in developing effective strategies to improve the pedestrian experience and reduce pedestrian-vehicle collisions at intersections.
Te circular economy encourages the production and consumption of sustainable embankment geomateri... more Te circular economy encourages the production and consumption of sustainable embankment geomaterials and their blends utilizing recycled waste materials in roads, railway tracks, airfelds, and underground structures. Geomaterials comprising highplastic soft expansive clay pose excessive settlement during cyclic trafc/railway/airfeld loading resulting in uneven geometry of overlying layers. Tis paper demonstrates multiobjective optimized improvement of expansive clay (C) geotechnical characteristics by cost-efective agro-wastes additives at microlevel (by 3% to 12% rice husk ash, i.e., RHA), nanolevel (by 0.6% to 1.5% rice husk derived green nano-SiO 2 , i.e., NS), and synergistic micro to nanolevel (NS-RHA). Te swell potential, resilient modulus (MR), initial elastic modulus (Es), unconfned compressive strength (UCT), and California bearing ratio (CBR) of C and its blends were determined. Te chemical characterization of C and its blends were conducted through Fourier transform infrared spectroscopy (FTIR) and optical microscopic tests. Te outcome of this study depicted that the cost ratio for the optimized composite, i.e., (1.2% NS-9% RHA)/(9% RHA) is 1.22 whereas stifness ratio MR (NS-RHA)/MR(RHA) and Es (NS-RHA)/ Es(RHA) and strength ratio UCT(NS-RHA)/UCT(RHA) and CBR(NS-RHA)/CBR(RHA) were found to be 2.0, 1.64, 2.17, and 2.82, respectively. FTIR revealed the chemical compatibility between C, RHA, & NS from durability perspective. Cost-stifness results of this study can be applied by geotechnical experts to economize the green stabilization of C by use of agro-waste for sustainable development.
The evaluation of fundamental mechanical properties of bitumen is vital to construct long-term pe... more The evaluation of fundamental mechanical properties of bitumen is vital to construct long-term performing pavements. This research evaluates cohesive bond strength of bitumen and mastics using compression pull-off test (CPOT). The results show problems in the common interpretation of load-displacement curves. A discussion is made on fibrillary nucleation in binder. The curing for 24 h is sufficient for the development of the cohesive bond. Furthermore, longer conditioning is needed to evaluate the moisture damage using aluminium plates. Bitumen source, grade, filler content, and loading rate affect the pull-off strength (POS). Ageing increases POS and shifts the failure mode towards brittle. The type of filler does not affect POS after short-term ageing. The moisture conditioning reduces the POS and results in a mixed to adhesive failure with increased variability in results. The aggregate plates are necessary for detailed moisture damage evaluation. The use of re-used aggregate substrate is found to be ineffective.
Geotechnical engineering design necessitates a study of soil parameters for calculation purposes.... more Geotechnical engineering design necessitates a study of soil parameters for calculation purposes. As a complement to the conventional method, a resistivity survey can give preliminary results in a short amount of time. Tis study uses a statistical analysis program to show a correlation and regression for predicting soil parameters based on the resistivity value. Sixty-six data points for each soil parameter and resistivity were used for statistical analysis from six profles of the study area as a part of the investigation. Te soils are sampled by drilling the borehole up to a depth of 3 meters. Te Wenner array was applied to conduct a resistivity survey. Te collected data were utilized to establish a correlation between resistivity (ρ) and soil parameters such as moisture content (w), clay content (clay), plasticity index (PI), friction angle (ϕ), bulk density (c), and porosity (n). Te generated statistic model was improved through several iterations for each correlation. For the ρ-w, ρ-clay, ρ-PI, ρ-ϕ, ρ-c, and ρ-n relationship, the total iterations are 5, 4, 7, 6, 5, and 4 for each correlation, respectively. Resistivity and moisture content showed a signifcant power correlation, followed by a modest relationship between resistivity and porosity. Between resistivity and other parameters, relationships such as clay content, bulk density, friction angle, and plasticity index were found to have very weak or no association. However, some trends can be seen clearly. Tis study aims to ofer the geotechnical engineer a quick preliminary way of obtaining the associated soil parameters for various geotechnical calculations employing the resistivity approach based on the developed numerical equation.
Recycled Coarse Aggregate for Sustainable Self-Compacting Concrete and Mortar, 2022
Te utilization of construction and demolition waste is useful for sustainable infrastructure deve... more Te utilization of construction and demolition waste is useful for sustainable infrastructure development and protecting the environment. In this research, the properties of self-compacting concrete produced by replacing the natural coarse aggregates (NCA) with inferior recycled coarse aggregates (RCA) were investigated. Te properties of self-compacting concrete (SCC) and self-compacting mortar (SCM) with varying replacements of RCA (0, 25, 50, and 100%) in NCA were determined. Te fow, strength, early shrinkage tests, and microstructure using X-ray difraction (XRD) and a scanning electron microscope (SEM) were investigated. Te fresh property results indicated that the viscosity of freshly mixed SCC increased with higher replacement levels of RCA, thus reducing fow. Te compressive strength of RCA SCC was reduced up to 30% for a 100% replacement level, while the fexural strength was reduced by about 15%. Te compressive strength and fexural strength of SCMs, however, increased up to 12% and 28% for 100% replacement with RCA. Te mechanical strength of SCM increases with RCA because of high fne content which reduces the porosity and makes the system denser. Te early age linear shrinkage increases with RCA due to its greater water absorption. Te results indicate that recycled coarse aggregate can be efectively used as the replacement of NCA in SCC to produce sustainable and eco-friendly structural concrete.
Evaluating the Performance of Aluminum Oxide Nanoparticle-Modified Asphalt Binder and Modelling the Viscoelastic Properties by Using Artificial Neural Networks and Support Vector Machines, 2022
Te efect of aluminum oxide nanoparticles (Al2 O3) on the 60/70 penetration of asphalt cement (AC)... more Te efect of aluminum oxide nanoparticles (Al2 O3) on the 60/70 penetration of asphalt cement (AC) was investigated in terms of the physical and rheological characteristics by using the Superpave testing procedures. Al 2 O 3 at 3, 5, and 7% concentrations were blended with 60/70 penetration of grade AC. Conventional testing procedures were adopted regarding the physical characteristics, while dynamic shear rheometer (DSR) testing procedures were conducted to evaluate the high and low temperature failure parameters. In addition, heuristic modelling techniques, artifcial neural networks (ANN), and support vector machines (SVM) were employed to predict the performance characteristics of AC by using the mechanical testing conditions. Te frequency sweep test and multiple stress creep recovery (MSCR) test results revealed that the optimum composition of Al 2 O 3 was at 5% concentration considering the high temperature performance characteristics since further addition of the Al 2 O 3 resulted in degradation in the enhanced properties due to agglomeration of the nanoparticles in the blend. On the contrary, Al 2 O 3 5% demonstrated the lowest viscoelastic behavior at intermediate temperatures. Te higher complex modulus (G *) and lower phase angle (δ) parameters indicated that the increase in stifness due to the modifcation process was at the cost of losing elastic properties against fatigue cracking. Moreover, based on the statistical performance indicator, coefcient of determination (R 2), it was observed that the ANN models for predicting G * and δ achieved a prediction accuracy of 0.989 and 0.911 while SVM models were able to achieve 0.984 and 0.929, respectively, considering the training datasets. On the other hand, it was noted that SVM models outperformed the ANN models in terms of a smaller gap between the results obtained from the training and testing datasets. Te diference between the training and testing datasets for G * and δ parameters for the SVM models were 3.2% and 6.8% while for the ANN models, the diferences were 11.6% and 9.5%, respectively, indicating that the ANN models were more prone to the overftting phenomenon.
Each year, massive amount of construction waste is generated that needs proper attention in terms... more Each year, massive amount of construction waste is generated that needs proper attention in terms of its disposal without deteriorating surrounding environment. A significant portion of this waste comprises bricks. Besides, large number of new construction works are resulting in the depletion of natural resources rapidly. Intuitively, a sustainable solution demands to consume this construction waste in the best way possible. This study targeted brick waste as a potential material to be used as a partial replacement of natural aggregates in structural concrete. It has been known that the concrete constructed with recycled brick aggregates possesses substandard mechanical properties. Traditionally, synthetic FRPs are known to strengthen recycled aggregate concrete. However, recognizing high costs associated with them, this study proposed the use of natural hemp fiber ropes to strengthen recycled aggregate concrete constructed with brick aggregates. To assess the efficacy of hemp ropes in strengthening mechanical properties of the concrete with coarse aggregates partially replaced with recycled brick aggregates (B-waste), an experimental framework was conducted. Sixteen cylindrical specimens were tested in two groups depending upon the concrete strength. Within each group, 2 specimens each were strengthened with 1, 2, and 3 layers of hemp fiber ropes. Axial monotonic compressive loading was applied to each specimen. Results revealed that hemp fiber ropes significantly improved ultimate compressive strength and the corresponding strain. A substantial improvement in axial ductility was observed. For the sake of performance-based non-linear modelling, accurate constitutive modelling at material level is necessary. For this purpose, several existing analytical stress-strain models were tested in this study to predict ultimate confined compressive strength and strain. It was found that several models predicted confined compressive strengths with reasonable accuracy. However, very few models were able to predict confined peak strain with good accuracy.
This research presents an investigation on the incorporation of atactic polypropylene (APP) as a ... more This research presents an investigation on the incorporation of atactic polypropylene (APP) as a modifier in bitumen at weight concentrations from 0 to 30 wt%. An APP-modified bitumen (APPMB) was prepared by conventional, hot, and in situ blending and characterized for mechanical, morphological, thermal, structural, and physical properties. APPMB specimens using maleic anhydride (MA) functionalized polymer at its optimized concentration of 20 weight percentage (wt%), along at several other concentrations, were prepared using in situ and hot blending methods using an overhead stirrer mixer at a blending temperature of 160°C for 2 h. Fourier transform infrared revealed a strong interaction of APP or APP-g-MA with bitumen. The ultimate compressive strength, acquired in Mega Pascal (MPa) units, was increased from 0.24 MPa at 5 wt% APP to 0.70 MPa at 20 wt% APP loading. Scanning electron microscopy micrographs manifested dispersed phases of APP in bitumen due to the high temperature and shearing application with overhead stirring. In situ and hot blended specimens exhibited better mechanical, thermal, and structure–property relations. This research highlights the novelty in terms of property optimization and advancements at a high-weight percentage of the modifier (i.e., 20 wt%) along with emphasizing the comparison of three different fabrication techniques; however, the previous research manifested the advancements in the properties of polymer and bitumen blends at low concentrations of polymers.
In this research, the mechanical properties and durability of sulfur concrete with two different ... more In this research, the mechanical properties and durability of sulfur concrete with two different waste aggregates were evalu-ated. The waste aggregates included ground granulated blast-furnace slag and waste marble powder. The properties of sulfur concrete were also compared with those of the conventional binder concretes (i.e., Portland cement concrete and sulfate-resistant cement concrete). The durability parameters included measuring water absorption capacity and resistance to different harsh chemical environments (5% HCl solution, 5 Molar NaOH solution, and 16% NaCl solution). It was found that sulfur concrete made with slag as aggregate exhibited the maximum strength, i.e., about 2 times higher than that of Portland cement concrete and sulfate-resistant cement concrete. Sulfur concrete made with slag and marble waste powder showed superior mechanical performance compared to that made with river sand. Thus, sulfur binder develops more favorable properties with eco-friendly fillers than it develops with natural sand. In harsh chloride and acidic environment, sulfur concrete with slag powder exhibited about 90–95% lesser mass loss than Portland cement concrete.
The bituminous binder's ageing process is the primary reason behind the decrement in the pavement... more The bituminous binder's ageing process is the primary reason behind the decrement in the pavement's in-service life, which can lead to cracking as a result of extreme hardening of the binder. In order to mitigate this problem, several methods have been used, such as polymer modification, functional improvement and modification with nano-particles. Due to its exceptional performance in asphalt mixtures, hydrated lime has also been considered the potential antioxidant in recent studies. However, its impacts have not been well understood. Therefore, this study aims to investigate the effect of hydrated lime and other fillers on mastic stiffening and ageing. In this detailed study on mastics, the effect of hydrated lime on stiffening and ageing mitigation was evaluated by various means involving both physical and chemical properties. The evaluation testing was aimed at understanding the mechanisms of hydrated lime on ageing mitigation. Moreover, special attention was paid to the interactions between hydrated lime and bitumen, which affects bitumen mastics' ageing. The results indicate that hydrated lime reduced the ageing indices more as compared to other fillers. Further, increasing the concentration of hydrated lime resulted in more decrease of ageing indices just opposite to that of granite filler. Also, the bitumen recovered from the hydrated lime mastics showed less carbonyl index and asphaltenes content than granite mastics which prove the ability of hydrated lime to reduce the ageing products. Moreover, it is noticed that the mastics stiffness increased with an increase in the ageing time. The fillers can increase or decrease the ageing of the mastics as the time in the TFOT proceeds.
The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) an... more The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) and filler (particulates phase). The interaction of bitumen and filler and packing of filler plays an important role in the properties of mastics. The micromechanics models from composite rheology can be used to predict the stiffening effect of a suspension. In this research, the stiffening effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (φm) and Einstien coefficient (KE) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling
The rising concerns about the environment and sustainability are leading towards the need of recy... more The rising concerns about the environment and sustainability are leading towards the need of recyclable materials to protect the environment and help in resource conservation. Sulfur concrete (SC) is a unique composite that does not utilize water and energy intensively produced cement. As a substitute to cement, molten sulfur firmly binds aggregates upon hardening. The sulfur concrete is recyclable and can be easily remolded in new applications. Moreover, sulfur is a by-product of the petroleum industry with almost zero carbon footprint. In this study, the mechanical (compressive strength and modulus of rupture) and durability properties (water absorption, salt attack-resistance, acid attack-resistance and alkali attack-resistance) of SC were evaluated after recasting without the addition of a new binder. The properties of fresh and recast SC were compared with those of the conventional Portland cement concrete (PCC) and sulfate resisting cement concrete (SRC). The results reveal that both the mechanical and durability properties of SC have significantly improved after the first recycling/recasting. However, there is a drastic decrease in strength and durability performance after the second recasting. Durability and mechanical performance of fresh and first recast SC is noticeably higher compared to PCC and SRC.
The quantification of moisture susceptibility has been a major concern for researchers as it adve... more The quantification of moisture susceptibility has been a major concern for researchers as it adversely affects the performance of asphalt pavements. Several methods have been developed to assess bond strength using asphalt mixtures in loose and compacted state. These tests lack in their ability to study fundamental properties that affect the bond between bitumen and aggregate. In this context, more fundamental techniques have been developed such as pull-off stub tests and direct tension tests. The first group only measures the maximum pull-off strength and second group has problems related to use of consistent binder film thickness and operational difficulties in test itself.
This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder.
The NASA ISRU project establishes the need for in-situ materials for the lunar base and Mars habi... more The NASA ISRU project establishes the need for in-situ materials for the lunar base and Mars habitation. Mars has the most favorable conditions for habitation and further deep space exploration. The understanding of planet conditions reveals that the temperature variations, solar radiations, and micrometeorite flux are much more favorable than the Moon and local materials are more readily available. Researchers are evaluating several materials and methods for in situ resource utilization (for example sulfur concrete, geopolymerisation, and additive technologies). The Martian regolith can be used as aggregate and binding materials such as sulfur and MgO/MgCl2 can be extracted locally. This research evaluates the case of sulfur concrete for its use in a hostile Martian environment as a construction material for habitation. The regolith properties were imitated by the use of earthly “stimulant” (MMS-2). The PSD and SEM indicate well graded but angular and highly processed aggregate. The suitable Martian concrete proportion is identified as 45% sulfur and 55% regolith. The results indicate that the slightly alkaline environment of Mars can affect the long-term performance of sulfur concrete.
This study investigates the feasibility and effect of poly(lactic) acid (PLA) on bitumen modifica... more This study investigates the feasibility and effect of poly(lactic) acid (PLA) on bitumen modification. The chemical and physical properties were evaluated for the modified bitumen produced with varying percentages of PLA ranging from 3 to 9%. Several testings such as the nuclear magnetic resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel permeation chromatography (GPC), penetration, softening and ductility, and thermal storage stability were evaluated. The results show that chemical interaction exists between PLA and bitumen. The GPC analysis indicates high compatibility of the bitumen with the PLA modifier. Moreover, the results indicated that the addition of PLA increased the consistency of modified bitumen. The storage stability and segregation of phases were positively affected in the PLA modified bitumen. The PLA and base bitumen interact at physical and chemical levels which results in enhancement of performance of modified bitumen to produce a high-quality binding material for pavement construction.
Travel pattern is a widely researched topic as it highly influences several urban planning and en... more Travel pattern is a widely researched topic as it highly influences several urban planning and engineering decisions. The pattern itself is impacted by several factors namely; gender difference, availability of transit facilities and their quality, users‟ perception and travel behavior etc. The impact of gender difference is believed be one of the most significant factors affecting the daily travel movement. It has been identified that females make less trips, work closer to their homes, and are more reliant on public transport than men [1, 2]. The public transport dependency, subject women to face greater ride challenges and thus efforts directed towards improvement in public transport positively affect them [3].
A study shows that women‟s trips mainly take place on public transport as travel on other modes such as riding motorcycle is still restricted. Additionally, there are challenges related to worries of safety, harassment, social image, and concerns related to getting to bus stops and waiting. A survey of 1,000 households in Lahore, 70% of males said they would discourage female family members from taking public wagon (a prevalent mode). Also, more than 30% of respondents felt that it was “extremely unsafe” for women to walk in their neighborhood. The existing women‟sonly services (in Lahore, three Pink Bus routes) services serve a small number of women due to their very limited coverage, restricted timings and lack of publicity. Moreover, many women in Lahore lack access to a bus with a omen‟s-only compartment [3].
According to World Bank, female labor force participation rate has doubled (12.51 % to 25.12%) from 1990 to 2018. However, this statistic does not classify females in their marital status and motherhood. The increasing travel movement has accentuated problems for women in developing countries; where females‟ travel is closely linked with socio-cultural norms and stereotypes set by the society. The prevalent issues are related to literacy rate and gender discrimination.
The young mothers, in particular, have increasing needs and demands of travel relative to unmarried, aged and married females rearing no children. The increasing travel demand of young mothers is related to trips in the form of chauffeuring to and from schools or other places, and other aggregated rational trips for household errands. The working mothers are burdened with additional trips to day care centers in addition to work, housekeeping and child rearing. The transportation of children to day care is expected to be a significant burden as it must be done in busy commuting times and within a narrow time constraint [4].
The fore-mentioned challenges impact females‟ travel pattern and restrict their choice of mode. Therefore, there is need to understand the complex trip chaining for the travel pattern of young mothers as well as other subgroups of females. It will assist in evaluating the efficient usage of resources for public transport services. The results will help to suggest feasible transport interventions that can improve females‟ travel pattern.
In the recent decade, an emerging trend is escalating in developing countries named as 'Rideshari... more In the recent decade, an emerging trend is escalating in developing countries named as 'Ridesharing Services' or 'Transportation Network Companies (TNCs)' and in Pakistan, TNCs are recently introduced. In this study, an online questionnaire survey included a stated preference experiment for three different transport alternatives: own vehicle, TNCs (i.e., Uber and Careem) and public transport. A total of 317 parents (149 females and 168 males) reported their preferences to use given alternatives based on their personal and trip characteristics. A multinomial logit model was used to describe the mode choice mechanism. The impacts of travel cost, privacy and safety concerns and travel time were identified based on household income, gender and type of profession. Results manifested that parents with middle-income and employees prefer TNCs, while high-income, female and business parents prefer personal vehicles considering trip characteristics. The extracted findings would provide a clear understanding of mode choice factors for the selected travel alternatives.
Freight transportation is a dynamic part of a country's economy and yield positive dimensions on ... more Freight transportation is a dynamic part of a country's economy and yield positive dimensions on GDP. This paper discusses the problems that why intelligent freight transportation, a prerequisite for the regional or international evolution and development, is relatively missing from the mainstream economic geography of Pakistan. This paper discusses the possible scenario-based impediments which hinder the intelligent operations of freight transportation in the region. The core scenario-based impediments discussed in this paper include; State Fleet Policy (SFP), Advanced Driver Assistance Systems (ADAS), Infrastructure Management Systems (IMS), and City Logistics (CL). The role of the most direct key factors along with their negative projections on impact areas impeding smart transportation logistics are also highlighted in this research. For future research, these implications will also be validated via expert surveys or a Delphi-analysis.
The use of planetary regolith can be explored via the utilization of simulants. The existing Mart... more The use of planetary regolith can be explored via the utilization of simulants. The existing Martian simulants have differences due to varying source materials and design parameters. Additional simulants are needed because the few available simulants do not replicate the compositional diversity of Martian regolith. This study discusses the development of a low-cost construction simulant of Mars. The area of Winder Nai in Pakistan was selected for field sampling of basalt because of local availability and easy access. The dust was produced from rock samples through mechanical crushing and grinding. The physical properties, composition, mineralogy, and surface morphology were evaluated via geotechnical tests, Energy Dispersive X-ray (EDX) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The designed simulant has a well-graded particle size distribution with a particle density and bulk density of 2.58 g/cm3 and 1.16 g/cm3, respectively. The elemental composition of Winder Nai Mars Simulant (WNMS) is within ±5 wt% of the Rocknest and the average Martian regolith composition except for SO3. For SiO2, Al2O3, and Fe2O3, WNMS has a good match with the Martian regolith. The content of CaO and TiO2 in WNMS is higher than, and content of MgO is lower than, the average Martian values. The rock can be classified as basalt based on the Total Alkali Silica (TAS) diagram. XRD spectrum indicates the occurrence of plagioclase and pyroxene as the main signature minerals of basalt. The particle morphology of WNMS is angular to subangular, and the simulant indicates the presence of 3.8 wt% highly paramagnetic particles. The volatile loss is 0.25 wt% at 100 °C, 1.73 wt% at 500 °C, and 3.05 wt% at 950 °C. The composition of WNMS, basaltic mineralogy, morphology, magnetic properties, and volatile content are comparable with MMS-2 and a few other simulants.
There has been an increase in plastic production during the past decades, yet the recycling of pl... more There has been an increase in plastic production during the past decades, yet the recycling of plastic remains relatively low. Incorporating plastic in concrete can mitigate environmental pollution. The use of waste polyethylene terephthalate (PET) bottles as an aggregate weakens properties of concrete. An alternative is to use PET bottles as a binder in the mortar. The PET binder mixed with sand results in weak mortar. Marble and iron slag can enhance PET mortar properties by preventing alkali reactions. This study examines the mechanical and durability properties of PET mortar with different mixes. The mixes were prepared as plastic and marble (PM); plastic and iron slag (PI); plastic, sand, and marble (PSM); plastic, iron slag, and marble (PIM); and plastic, sand, and iron slag (PSI). PM with 30–45% plastic content had increased compressive and flexural strength up to 35.73% and 20.21%, respectively. PI with 30–35% plastic content showed strength improvements up to 29.19% and 5.02%, respectively. However, at 45% plastic content, strength decreased by 8.8% and 27.90%. PSM, PIM, and PSI specimens had nearly double the strength of ordinary Portland cement (OPC) mortar. The durability of PET mortar in chemical solutions, mainly 5% HCl and 20% NaOH, indicate that mass decreased after 3, 7, and 28 days. All specimens showed good resistance to HCl and NaCl solutions compared to OPC mortar. However, its resistance to NaOH is low compared to OPC mortar. PET mortar without cement showed higher strength and durability than cement mortar, making it suitable for paver tiles, drainage systems, and roads.
Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences, 2023
Pedestrians’ safe mobility at intersections is associated with the facilities provided at the cro... more Pedestrians’ safe mobility at intersections is associated with the facilities provided at the crossings. Lahore is one of the most populous cities in Pakistan. Too many road accidents occur daily at various areas of Lahore in which pedestrian-vehicle collision has a major ratio. To reduce the pedestrian-vehicle collisions, pedestrian signals are installed at major intersections of Lahore city. This paper examines the relationship between pedestrian signals and Level of Service (LOS), with a focus on enhancing awareness of pedestrian signal operation and investigates the impact of pedestrian signals on the LOS of intersections in Lahore in terms of pedestrian movement. Research shows that the poor level of awareness about how pedestrian signals work contributes to the inadequate level of service of intersections in terms of pedestrian movement. The results also provide valuable insights for policymakers and practitioners in developing effective strategies to improve the pedestrian experience and reduce pedestrian-vehicle collisions at intersections.
Te circular economy encourages the production and consumption of sustainable embankment geomateri... more Te circular economy encourages the production and consumption of sustainable embankment geomaterials and their blends utilizing recycled waste materials in roads, railway tracks, airfelds, and underground structures. Geomaterials comprising highplastic soft expansive clay pose excessive settlement during cyclic trafc/railway/airfeld loading resulting in uneven geometry of overlying layers. Tis paper demonstrates multiobjective optimized improvement of expansive clay (C) geotechnical characteristics by cost-efective agro-wastes additives at microlevel (by 3% to 12% rice husk ash, i.e., RHA), nanolevel (by 0.6% to 1.5% rice husk derived green nano-SiO 2 , i.e., NS), and synergistic micro to nanolevel (NS-RHA). Te swell potential, resilient modulus (MR), initial elastic modulus (Es), unconfned compressive strength (UCT), and California bearing ratio (CBR) of C and its blends were determined. Te chemical characterization of C and its blends were conducted through Fourier transform infrared spectroscopy (FTIR) and optical microscopic tests. Te outcome of this study depicted that the cost ratio for the optimized composite, i.e., (1.2% NS-9% RHA)/(9% RHA) is 1.22 whereas stifness ratio MR (NS-RHA)/MR(RHA) and Es (NS-RHA)/ Es(RHA) and strength ratio UCT(NS-RHA)/UCT(RHA) and CBR(NS-RHA)/CBR(RHA) were found to be 2.0, 1.64, 2.17, and 2.82, respectively. FTIR revealed the chemical compatibility between C, RHA, & NS from durability perspective. Cost-stifness results of this study can be applied by geotechnical experts to economize the green stabilization of C by use of agro-waste for sustainable development.
The evaluation of fundamental mechanical properties of bitumen is vital to construct long-term pe... more The evaluation of fundamental mechanical properties of bitumen is vital to construct long-term performing pavements. This research evaluates cohesive bond strength of bitumen and mastics using compression pull-off test (CPOT). The results show problems in the common interpretation of load-displacement curves. A discussion is made on fibrillary nucleation in binder. The curing for 24 h is sufficient for the development of the cohesive bond. Furthermore, longer conditioning is needed to evaluate the moisture damage using aluminium plates. Bitumen source, grade, filler content, and loading rate affect the pull-off strength (POS). Ageing increases POS and shifts the failure mode towards brittle. The type of filler does not affect POS after short-term ageing. The moisture conditioning reduces the POS and results in a mixed to adhesive failure with increased variability in results. The aggregate plates are necessary for detailed moisture damage evaluation. The use of re-used aggregate substrate is found to be ineffective.
Geotechnical engineering design necessitates a study of soil parameters for calculation purposes.... more Geotechnical engineering design necessitates a study of soil parameters for calculation purposes. As a complement to the conventional method, a resistivity survey can give preliminary results in a short amount of time. Tis study uses a statistical analysis program to show a correlation and regression for predicting soil parameters based on the resistivity value. Sixty-six data points for each soil parameter and resistivity were used for statistical analysis from six profles of the study area as a part of the investigation. Te soils are sampled by drilling the borehole up to a depth of 3 meters. Te Wenner array was applied to conduct a resistivity survey. Te collected data were utilized to establish a correlation between resistivity (ρ) and soil parameters such as moisture content (w), clay content (clay), plasticity index (PI), friction angle (ϕ), bulk density (c), and porosity (n). Te generated statistic model was improved through several iterations for each correlation. For the ρ-w, ρ-clay, ρ-PI, ρ-ϕ, ρ-c, and ρ-n relationship, the total iterations are 5, 4, 7, 6, 5, and 4 for each correlation, respectively. Resistivity and moisture content showed a signifcant power correlation, followed by a modest relationship between resistivity and porosity. Between resistivity and other parameters, relationships such as clay content, bulk density, friction angle, and plasticity index were found to have very weak or no association. However, some trends can be seen clearly. Tis study aims to ofer the geotechnical engineer a quick preliminary way of obtaining the associated soil parameters for various geotechnical calculations employing the resistivity approach based on the developed numerical equation.
Recycled Coarse Aggregate for Sustainable Self-Compacting Concrete and Mortar, 2022
Te utilization of construction and demolition waste is useful for sustainable infrastructure deve... more Te utilization of construction and demolition waste is useful for sustainable infrastructure development and protecting the environment. In this research, the properties of self-compacting concrete produced by replacing the natural coarse aggregates (NCA) with inferior recycled coarse aggregates (RCA) were investigated. Te properties of self-compacting concrete (SCC) and self-compacting mortar (SCM) with varying replacements of RCA (0, 25, 50, and 100%) in NCA were determined. Te fow, strength, early shrinkage tests, and microstructure using X-ray difraction (XRD) and a scanning electron microscope (SEM) were investigated. Te fresh property results indicated that the viscosity of freshly mixed SCC increased with higher replacement levels of RCA, thus reducing fow. Te compressive strength of RCA SCC was reduced up to 30% for a 100% replacement level, while the fexural strength was reduced by about 15%. Te compressive strength and fexural strength of SCMs, however, increased up to 12% and 28% for 100% replacement with RCA. Te mechanical strength of SCM increases with RCA because of high fne content which reduces the porosity and makes the system denser. Te early age linear shrinkage increases with RCA due to its greater water absorption. Te results indicate that recycled coarse aggregate can be efectively used as the replacement of NCA in SCC to produce sustainable and eco-friendly structural concrete.
Evaluating the Performance of Aluminum Oxide Nanoparticle-Modified Asphalt Binder and Modelling the Viscoelastic Properties by Using Artificial Neural Networks and Support Vector Machines, 2022
Te efect of aluminum oxide nanoparticles (Al2 O3) on the 60/70 penetration of asphalt cement (AC)... more Te efect of aluminum oxide nanoparticles (Al2 O3) on the 60/70 penetration of asphalt cement (AC) was investigated in terms of the physical and rheological characteristics by using the Superpave testing procedures. Al 2 O 3 at 3, 5, and 7% concentrations were blended with 60/70 penetration of grade AC. Conventional testing procedures were adopted regarding the physical characteristics, while dynamic shear rheometer (DSR) testing procedures were conducted to evaluate the high and low temperature failure parameters. In addition, heuristic modelling techniques, artifcial neural networks (ANN), and support vector machines (SVM) were employed to predict the performance characteristics of AC by using the mechanical testing conditions. Te frequency sweep test and multiple stress creep recovery (MSCR) test results revealed that the optimum composition of Al 2 O 3 was at 5% concentration considering the high temperature performance characteristics since further addition of the Al 2 O 3 resulted in degradation in the enhanced properties due to agglomeration of the nanoparticles in the blend. On the contrary, Al 2 O 3 5% demonstrated the lowest viscoelastic behavior at intermediate temperatures. Te higher complex modulus (G *) and lower phase angle (δ) parameters indicated that the increase in stifness due to the modifcation process was at the cost of losing elastic properties against fatigue cracking. Moreover, based on the statistical performance indicator, coefcient of determination (R 2), it was observed that the ANN models for predicting G * and δ achieved a prediction accuracy of 0.989 and 0.911 while SVM models were able to achieve 0.984 and 0.929, respectively, considering the training datasets. On the other hand, it was noted that SVM models outperformed the ANN models in terms of a smaller gap between the results obtained from the training and testing datasets. Te diference between the training and testing datasets for G * and δ parameters for the SVM models were 3.2% and 6.8% while for the ANN models, the diferences were 11.6% and 9.5%, respectively, indicating that the ANN models were more prone to the overftting phenomenon.
Each year, massive amount of construction waste is generated that needs proper attention in terms... more Each year, massive amount of construction waste is generated that needs proper attention in terms of its disposal without deteriorating surrounding environment. A significant portion of this waste comprises bricks. Besides, large number of new construction works are resulting in the depletion of natural resources rapidly. Intuitively, a sustainable solution demands to consume this construction waste in the best way possible. This study targeted brick waste as a potential material to be used as a partial replacement of natural aggregates in structural concrete. It has been known that the concrete constructed with recycled brick aggregates possesses substandard mechanical properties. Traditionally, synthetic FRPs are known to strengthen recycled aggregate concrete. However, recognizing high costs associated with them, this study proposed the use of natural hemp fiber ropes to strengthen recycled aggregate concrete constructed with brick aggregates. To assess the efficacy of hemp ropes in strengthening mechanical properties of the concrete with coarse aggregates partially replaced with recycled brick aggregates (B-waste), an experimental framework was conducted. Sixteen cylindrical specimens were tested in two groups depending upon the concrete strength. Within each group, 2 specimens each were strengthened with 1, 2, and 3 layers of hemp fiber ropes. Axial monotonic compressive loading was applied to each specimen. Results revealed that hemp fiber ropes significantly improved ultimate compressive strength and the corresponding strain. A substantial improvement in axial ductility was observed. For the sake of performance-based non-linear modelling, accurate constitutive modelling at material level is necessary. For this purpose, several existing analytical stress-strain models were tested in this study to predict ultimate confined compressive strength and strain. It was found that several models predicted confined compressive strengths with reasonable accuracy. However, very few models were able to predict confined peak strain with good accuracy.
This research presents an investigation on the incorporation of atactic polypropylene (APP) as a ... more This research presents an investigation on the incorporation of atactic polypropylene (APP) as a modifier in bitumen at weight concentrations from 0 to 30 wt%. An APP-modified bitumen (APPMB) was prepared by conventional, hot, and in situ blending and characterized for mechanical, morphological, thermal, structural, and physical properties. APPMB specimens using maleic anhydride (MA) functionalized polymer at its optimized concentration of 20 weight percentage (wt%), along at several other concentrations, were prepared using in situ and hot blending methods using an overhead stirrer mixer at a blending temperature of 160°C for 2 h. Fourier transform infrared revealed a strong interaction of APP or APP-g-MA with bitumen. The ultimate compressive strength, acquired in Mega Pascal (MPa) units, was increased from 0.24 MPa at 5 wt% APP to 0.70 MPa at 20 wt% APP loading. Scanning electron microscopy micrographs manifested dispersed phases of APP in bitumen due to the high temperature and shearing application with overhead stirring. In situ and hot blended specimens exhibited better mechanical, thermal, and structure–property relations. This research highlights the novelty in terms of property optimization and advancements at a high-weight percentage of the modifier (i.e., 20 wt%) along with emphasizing the comparison of three different fabrication techniques; however, the previous research manifested the advancements in the properties of polymer and bitumen blends at low concentrations of polymers.
In this research, the mechanical properties and durability of sulfur concrete with two different ... more In this research, the mechanical properties and durability of sulfur concrete with two different waste aggregates were evalu-ated. The waste aggregates included ground granulated blast-furnace slag and waste marble powder. The properties of sulfur concrete were also compared with those of the conventional binder concretes (i.e., Portland cement concrete and sulfate-resistant cement concrete). The durability parameters included measuring water absorption capacity and resistance to different harsh chemical environments (5% HCl solution, 5 Molar NaOH solution, and 16% NaCl solution). It was found that sulfur concrete made with slag as aggregate exhibited the maximum strength, i.e., about 2 times higher than that of Portland cement concrete and sulfate-resistant cement concrete. Sulfur concrete made with slag and marble waste powder showed superior mechanical performance compared to that made with river sand. Thus, sulfur binder develops more favorable properties with eco-friendly fillers than it develops with natural sand. In harsh chloride and acidic environment, sulfur concrete with slag powder exhibited about 90–95% lesser mass loss than Portland cement concrete.
The bituminous binder's ageing process is the primary reason behind the decrement in the pavement... more The bituminous binder's ageing process is the primary reason behind the decrement in the pavement's in-service life, which can lead to cracking as a result of extreme hardening of the binder. In order to mitigate this problem, several methods have been used, such as polymer modification, functional improvement and modification with nano-particles. Due to its exceptional performance in asphalt mixtures, hydrated lime has also been considered the potential antioxidant in recent studies. However, its impacts have not been well understood. Therefore, this study aims to investigate the effect of hydrated lime and other fillers on mastic stiffening and ageing. In this detailed study on mastics, the effect of hydrated lime on stiffening and ageing mitigation was evaluated by various means involving both physical and chemical properties. The evaluation testing was aimed at understanding the mechanisms of hydrated lime on ageing mitigation. Moreover, special attention was paid to the interactions between hydrated lime and bitumen, which affects bitumen mastics' ageing. The results indicate that hydrated lime reduced the ageing indices more as compared to other fillers. Further, increasing the concentration of hydrated lime resulted in more decrease of ageing indices just opposite to that of granite filler. Also, the bitumen recovered from the hydrated lime mastics showed less carbonyl index and asphaltenes content than granite mastics which prove the ability of hydrated lime to reduce the ageing products. Moreover, it is noticed that the mastics stiffness increased with an increase in the ageing time. The fillers can increase or decrease the ageing of the mastics as the time in the TFOT proceeds.
The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) an... more The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) and filler (particulates phase). The interaction of bitumen and filler and packing of filler plays an important role in the properties of mastics. The micromechanics models from composite rheology can be used to predict the stiffening effect of a suspension. In this research, the stiffening effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (φm) and Einstien coefficient (KE) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling
The rising concerns about the environment and sustainability are leading towards the need of recy... more The rising concerns about the environment and sustainability are leading towards the need of recyclable materials to protect the environment and help in resource conservation. Sulfur concrete (SC) is a unique composite that does not utilize water and energy intensively produced cement. As a substitute to cement, molten sulfur firmly binds aggregates upon hardening. The sulfur concrete is recyclable and can be easily remolded in new applications. Moreover, sulfur is a by-product of the petroleum industry with almost zero carbon footprint. In this study, the mechanical (compressive strength and modulus of rupture) and durability properties (water absorption, salt attack-resistance, acid attack-resistance and alkali attack-resistance) of SC were evaluated after recasting without the addition of a new binder. The properties of fresh and recast SC were compared with those of the conventional Portland cement concrete (PCC) and sulfate resisting cement concrete (SRC). The results reveal that both the mechanical and durability properties of SC have significantly improved after the first recycling/recasting. However, there is a drastic decrease in strength and durability performance after the second recasting. Durability and mechanical performance of fresh and first recast SC is noticeably higher compared to PCC and SRC.
The quantification of moisture susceptibility has been a major concern for researchers as it adve... more The quantification of moisture susceptibility has been a major concern for researchers as it adversely affects the performance of asphalt pavements. Several methods have been developed to assess bond strength using asphalt mixtures in loose and compacted state. These tests lack in their ability to study fundamental properties that affect the bond between bitumen and aggregate. In this context, more fundamental techniques have been developed such as pull-off stub tests and direct tension tests. The first group only measures the maximum pull-off strength and second group has problems related to use of consistent binder film thickness and operational difficulties in test itself.
This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder.
The NASA ISRU project establishes the need for in-situ materials for the lunar base and Mars habi... more The NASA ISRU project establishes the need for in-situ materials for the lunar base and Mars habitation. Mars has the most favorable conditions for habitation and further deep space exploration. The understanding of planet conditions reveals that the temperature variations, solar radiations, and micrometeorite flux are much more favorable than the Moon and local materials are more readily available. Researchers are evaluating several materials and methods for in situ resource utilization (for example sulfur concrete, geopolymerisation, and additive technologies). The Martian regolith can be used as aggregate and binding materials such as sulfur and MgO/MgCl2 can be extracted locally. This research evaluates the case of sulfur concrete for its use in a hostile Martian environment as a construction material for habitation. The regolith properties were imitated by the use of earthly “stimulant” (MMS-2). The PSD and SEM indicate well graded but angular and highly processed aggregate. The suitable Martian concrete proportion is identified as 45% sulfur and 55% regolith. The results indicate that the slightly alkaline environment of Mars can affect the long-term performance of sulfur concrete.
This study investigates the feasibility and effect of poly(lactic) acid (PLA) on bitumen modifica... more This study investigates the feasibility and effect of poly(lactic) acid (PLA) on bitumen modification. The chemical and physical properties were evaluated for the modified bitumen produced with varying percentages of PLA ranging from 3 to 9%. Several testings such as the nuclear magnetic resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel permeation chromatography (GPC), penetration, softening and ductility, and thermal storage stability were evaluated. The results show that chemical interaction exists between PLA and bitumen. The GPC analysis indicates high compatibility of the bitumen with the PLA modifier. Moreover, the results indicated that the addition of PLA increased the consistency of modified bitumen. The storage stability and segregation of phases were positively affected in the PLA modified bitumen. The PLA and base bitumen interact at physical and chemical levels which results in enhancement of performance of modified bitumen to produce a high-quality binding material for pavement construction.
Travel pattern is a widely researched topic as it highly influences several urban planning and en... more Travel pattern is a widely researched topic as it highly influences several urban planning and engineering decisions. The pattern itself is impacted by several factors namely; gender difference, availability of transit facilities and their quality, users‟ perception and travel behavior etc. The impact of gender difference is believed be one of the most significant factors affecting the daily travel movement. It has been identified that females make less trips, work closer to their homes, and are more reliant on public transport than men [1, 2]. The public transport dependency, subject women to face greater ride challenges and thus efforts directed towards improvement in public transport positively affect them [3].
A study shows that women‟s trips mainly take place on public transport as travel on other modes such as riding motorcycle is still restricted. Additionally, there are challenges related to worries of safety, harassment, social image, and concerns related to getting to bus stops and waiting. A survey of 1,000 households in Lahore, 70% of males said they would discourage female family members from taking public wagon (a prevalent mode). Also, more than 30% of respondents felt that it was “extremely unsafe” for women to walk in their neighborhood. The existing women‟sonly services (in Lahore, three Pink Bus routes) services serve a small number of women due to their very limited coverage, restricted timings and lack of publicity. Moreover, many women in Lahore lack access to a bus with a omen‟s-only compartment [3].
According to World Bank, female labor force participation rate has doubled (12.51 % to 25.12%) from 1990 to 2018. However, this statistic does not classify females in their marital status and motherhood. The increasing travel movement has accentuated problems for women in developing countries; where females‟ travel is closely linked with socio-cultural norms and stereotypes set by the society. The prevalent issues are related to literacy rate and gender discrimination.
The young mothers, in particular, have increasing needs and demands of travel relative to unmarried, aged and married females rearing no children. The increasing travel demand of young mothers is related to trips in the form of chauffeuring to and from schools or other places, and other aggregated rational trips for household errands. The working mothers are burdened with additional trips to day care centers in addition to work, housekeeping and child rearing. The transportation of children to day care is expected to be a significant burden as it must be done in busy commuting times and within a narrow time constraint [4].
The fore-mentioned challenges impact females‟ travel pattern and restrict their choice of mode. Therefore, there is need to understand the complex trip chaining for the travel pattern of young mothers as well as other subgroups of females. It will assist in evaluating the efficient usage of resources for public transport services. The results will help to suggest feasible transport interventions that can improve females‟ travel pattern.
In the recent decade, an emerging trend is escalating in developing countries named as 'Rideshari... more In the recent decade, an emerging trend is escalating in developing countries named as 'Ridesharing Services' or 'Transportation Network Companies (TNCs)' and in Pakistan, TNCs are recently introduced. In this study, an online questionnaire survey included a stated preference experiment for three different transport alternatives: own vehicle, TNCs (i.e., Uber and Careem) and public transport. A total of 317 parents (149 females and 168 males) reported their preferences to use given alternatives based on their personal and trip characteristics. A multinomial logit model was used to describe the mode choice mechanism. The impacts of travel cost, privacy and safety concerns and travel time were identified based on household income, gender and type of profession. Results manifested that parents with middle-income and employees prefer TNCs, while high-income, female and business parents prefer personal vehicles considering trip characteristics. The extracted findings would provide a clear understanding of mode choice factors for the selected travel alternatives.
Freight transportation is a dynamic part of a country's economy and yield positive dimensions on ... more Freight transportation is a dynamic part of a country's economy and yield positive dimensions on GDP. This paper discusses the problems that why intelligent freight transportation, a prerequisite for the regional or international evolution and development, is relatively missing from the mainstream economic geography of Pakistan. This paper discusses the possible scenario-based impediments which hinder the intelligent operations of freight transportation in the region. The core scenario-based impediments discussed in this paper include; State Fleet Policy (SFP), Advanced Driver Assistance Systems (ADAS), Infrastructure Management Systems (IMS), and City Logistics (CL). The role of the most direct key factors along with their negative projections on impact areas impeding smart transportation logistics are also highlighted in this research. For future research, these implications will also be validated via expert surveys or a Delphi-analysis.
The surface of planetary bodies is covered with loose unconsolidated material referred to as rego... more The surface of planetary bodies is covered with loose unconsolidated material referred to as regolith. The regolith is being studied by space agencies and academia to understand planetary processes, mission landings, rover operations habitation, and in situ resource utilization.
It is very expensive to transport the resources from earth to lunar base and Mars outpost and beyond. Planetary regolith can directly be used for construction material in compacted form and as a composite. Moreover, regolith and regolith-based habitats can provide a good shield against harmful galactic cosmic rays (GCRs), solar flares, and solar winds. The properties of regolith are imitated using laboratory-developed simulants. These simulants are specifically designed to match certain properties such as magnetic, optic, and geotechnical properties etc. The required properties are then used to select or modify the earth rock dust to replicate the regolith.
The observations through telescopes, orbiters, landers, rovers, and study of meteorite with the origin of Mars has revealed it to be a sulfur-rich planet. These two ingredients can be mixed to create Martian concrete. A detailed discussion of the environment of Mars and the properties of sulfur concrete can be found in Rahim et al. (2021).
In this research, the simulant of Mars regolith was imported from the United States. The particle density and particle size distribution were determined. The surface morphology was studied through Scanning Electron Microscopy (SEM). The simulant and sulfur were mixed in different proportions to produce Martian concrete. We have addressed the need to utilize regolith and local resources for extraterrestrial construction.
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Papers by Abdur Rahim
effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (φm) and Einstien coefficient
(KE) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling
This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder.
A study shows that women‟s trips mainly take place on public transport as travel on other modes such as riding motorcycle is still restricted. Additionally, there are challenges related to worries of safety, harassment, social image, and concerns related to getting to bus stops and waiting. A survey of 1,000 households in Lahore, 70% of males said they would discourage female family members from taking public wagon (a prevalent mode). Also, more than 30% of respondents felt that it was “extremely unsafe” for women to walk in their neighborhood. The existing women‟sonly services (in Lahore, three Pink Bus routes) services serve a small number of women due to their very limited coverage, restricted timings and lack of publicity. Moreover, many women in Lahore lack access to a bus with a omen‟s-only compartment [3].
According to World Bank, female labor force participation rate has doubled (12.51 % to 25.12%) from 1990 to 2018. However, this statistic does not classify females in their marital status and motherhood. The increasing travel movement has accentuated problems for women in developing countries; where females‟ travel is closely linked with socio-cultural norms and stereotypes set by the society. The prevalent issues are related to literacy rate and gender discrimination.
The young mothers, in particular, have increasing needs and demands of travel relative to unmarried, aged and married females rearing no children. The increasing travel demand of young mothers is related to trips in the form of chauffeuring to and from schools or other places, and other aggregated rational trips for household errands. The working mothers are burdened with additional trips to day care centers in addition to work, housekeeping and child rearing. The transportation of children to day care is expected to be a significant burden as it must be done in busy commuting times and within a narrow time constraint [4].
The fore-mentioned challenges impact females‟ travel pattern and restrict their choice of mode. Therefore, there is need to understand the complex trip chaining for the travel pattern of young mothers as well as other subgroups of females. It will assist in evaluating the efficient usage of resources for public transport services. The results will help to suggest feasible transport interventions that can improve females‟ travel pattern.
effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (φm) and Einstien coefficient
(KE) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling
This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder.
A study shows that women‟s trips mainly take place on public transport as travel on other modes such as riding motorcycle is still restricted. Additionally, there are challenges related to worries of safety, harassment, social image, and concerns related to getting to bus stops and waiting. A survey of 1,000 households in Lahore, 70% of males said they would discourage female family members from taking public wagon (a prevalent mode). Also, more than 30% of respondents felt that it was “extremely unsafe” for women to walk in their neighborhood. The existing women‟sonly services (in Lahore, three Pink Bus routes) services serve a small number of women due to their very limited coverage, restricted timings and lack of publicity. Moreover, many women in Lahore lack access to a bus with a omen‟s-only compartment [3].
According to World Bank, female labor force participation rate has doubled (12.51 % to 25.12%) from 1990 to 2018. However, this statistic does not classify females in their marital status and motherhood. The increasing travel movement has accentuated problems for women in developing countries; where females‟ travel is closely linked with socio-cultural norms and stereotypes set by the society. The prevalent issues are related to literacy rate and gender discrimination.
The young mothers, in particular, have increasing needs and demands of travel relative to unmarried, aged and married females rearing no children. The increasing travel demand of young mothers is related to trips in the form of chauffeuring to and from schools or other places, and other aggregated rational trips for household errands. The working mothers are burdened with additional trips to day care centers in addition to work, housekeeping and child rearing. The transportation of children to day care is expected to be a significant burden as it must be done in busy commuting times and within a narrow time constraint [4].
The fore-mentioned challenges impact females‟ travel pattern and restrict their choice of mode. Therefore, there is need to understand the complex trip chaining for the travel pattern of young mothers as well as other subgroups of females. It will assist in evaluating the efficient usage of resources for public transport services. The results will help to suggest feasible transport interventions that can improve females‟ travel pattern.
It is very expensive to transport the resources from earth to lunar base and Mars outpost and beyond. Planetary regolith can directly be used for construction material in compacted form and as a composite. Moreover, regolith and regolith-based habitats can provide a good shield against harmful galactic cosmic rays (GCRs), solar flares, and solar winds. The properties of regolith are imitated using laboratory-developed simulants. These simulants are specifically designed to match certain properties such as magnetic, optic, and geotechnical properties etc. The required properties are then used to select or modify the earth rock dust to replicate the regolith.
The observations through telescopes, orbiters, landers, rovers, and study of meteorite with the origin of Mars has revealed it to be a sulfur-rich planet. These two ingredients can be mixed to create Martian concrete. A detailed discussion of the environment of Mars and the properties of sulfur concrete can be found in Rahim et al. (2021).
In this research, the simulant of Mars regolith was imported from the United States. The particle density and particle size distribution were determined. The surface morphology was studied through Scanning Electron Microscopy (SEM). The simulant and sulfur were mixed in different proportions to produce Martian concrete. We have addressed the need to utilize regolith and local resources for extraterrestrial construction.