- +218913761046
Ahmed Eltwati
University of Benghazi, Civil Engineering, Faculty Member
- Traffic Engineering, Highway engineering, Road Safety, Traffic Enforcement, Driver Education, Highway Engineering, Pavement Engineering, Pavement Materials, Pavement design and analysis, and 7 moreHighway and Transportation systems, Block Pavement, Asphalt, Flexible Pavement Design, Highway & Bridge Engineering, Asphalt Pavements, and Asphalt materialedit
- University lecturer with strong academic and teaching background, possessing solid experience managing degree program... moreUniversity lecturer with strong academic and teaching background, possessing solid experience managing degree programs. Nearly 9 years’ significant experience demonstrating excellent teaching that fosters students’ critical skills leading to significantly improved performance. Comfortable within all teaching environments and able to demonstrate a vast range of other transferable skills and organization / administrative expertise.edit
- PROF. IR.DR. HASANAN BIN MD. NORedit
Climate change and limited power supplies receive significant incentives to develop alternative paving materials and technologies. Reclaimed asphalt pavement (RAP) and Warm Mix Asphalt (WMA) are technologies that can provide significant... more
Climate change and limited power supplies receive significant incentives to develop alternative paving materials and technologies. Reclaimed asphalt pavement (RAP) and Warm Mix Asphalt (WMA) are technologies that can provide significant benefits to both the environment and the economy. This study used response surface methodology (RSM) to analyze the rutting resistance and moisture susceptibility of asphalt mixtures containing different amounts of RAP and doses and types of WMA. The experimental design was established utilizing the RSM with a central composite design (CCD) for varying RAP dosages (25-50%), WMA amounts (1.5-4%), and WMA types (waxy organic Asphaltan type A ® , and waxy organic Asphaltan type B ®). The moisture sensitivity and rutting resistance of asphalt samples were evaluated using the Modified Lottman method (AASHTO T 283) and wheel tracking test, respectively. RSM's statistical and mathematical models were employed to estimate the optimal value for RAP dose and WMA content and type. The results demonstrated that adding RAP to WMA mixtures increased the rutting and moisture resistance of asphalt samples. Also, the analysis of variance (ANOVA) results indicated that the increase in the WMA content led to a significant decrease in the rutting resistance, while the rise in the RAP content contributed to a significant enhancement in the rutting performance of the samples. The statistical outcome also showed that the moisture susceptibility of the mixture decreased significantly after increasing the RAP content, while the increase in WMA content did not have a significant influence on the moisture performance of the mix regardless of the WMA type. The research indicated that rutting resistance and moisture susceptibility have significant correlation coefficients (R2) of > 0.92, indicating that the model is highly correlated with the experimental results. Multiobjective numerical optimization led to the optimal design with 50% RAP and 1.5% WMA-type A. Validation findings indicate strong agreement and model effectiveness, with an error variance of less than 5% for all responses.
Styrene-butadiene rubber (SBR) latex is used widely to increase the low-temperature resistance of asphalt binders. However, the high content of butadiene copolymer in SBR-treated asphalt causes oxidation and aging. Furthermore,... more
Styrene-butadiene rubber (SBR) latex is used widely to increase the low-temperature resistance of
asphalt binders. However, the high content of butadiene copolymer in SBR-treated asphalt causes
oxidation and aging. Furthermore, following the SBR modification, the compatibility and thermal
storage stability of SBR-modified asphalt is not satisfactory. Therefore, the best approach to
improve the quality of short-term aged SBR-modified asphalt is to lower the manufacturing
temperatures of the SBR-modified asphalt mixture. In this study, to reduce the preparation
temperatures of SBR-modified asphalt mixes and improve their performance after short-term
aging, several additives i.e., waste engine oil (WEO), warm mix agent i.e., ZycoTherm, and
WEO/ZycoTherm combination (WEO+ZycoTherm) were selected. The rheological properties and
aging performance of binder samples were evaluated through the rational viscosity, dynamic
shear rheometer, bending beam rheometer and Fourier transform infrared spectroscopy tests. The
results showed that adding WEO together with ZycoTherm into an SBR-modified binder
contributed to reducing the compaction and mixing temperatures. The chemical analysis showed
that the three additives i.e., WEO, ZycoTherm, and ZycoTherm/WEO declined the aromaticity
and chemical aging indicators of aged SBR-modified binders. Furthermore, it was demonstrated
that both the ZycoTherm and WEO/ZycoTherm improved the asphalt resistance to rutting at
elevated temperatures in both conditions i.e., before and after short-term aging. In addition, the
findings revealed ZycoTherm /WEO compound yielded the best performance to improve the
minimal-temperature cracking resistance of the SBR-modified binder, resulting in lower short-
term aging temperatures. In summary, this study highlights the necessity of lowering prepara-tion
temperatures in asphalt mixes containing SBR to enhance binder resistance to rutting and
cracking and reduce susceptibility to oxidation during short-term aging.
asphalt binders. However, the high content of butadiene copolymer in SBR-treated asphalt causes
oxidation and aging. Furthermore, following the SBR modification, the compatibility and thermal
storage stability of SBR-modified asphalt is not satisfactory. Therefore, the best approach to
improve the quality of short-term aged SBR-modified asphalt is to lower the manufacturing
temperatures of the SBR-modified asphalt mixture. In this study, to reduce the preparation
temperatures of SBR-modified asphalt mixes and improve their performance after short-term
aging, several additives i.e., waste engine oil (WEO), warm mix agent i.e., ZycoTherm, and
WEO/ZycoTherm combination (WEO+ZycoTherm) were selected. The rheological properties and
aging performance of binder samples were evaluated through the rational viscosity, dynamic
shear rheometer, bending beam rheometer and Fourier transform infrared spectroscopy tests. The
results showed that adding WEO together with ZycoTherm into an SBR-modified binder
contributed to reducing the compaction and mixing temperatures. The chemical analysis showed
that the three additives i.e., WEO, ZycoTherm, and ZycoTherm/WEO declined the aromaticity
and chemical aging indicators of aged SBR-modified binders. Furthermore, it was demonstrated
that both the ZycoTherm and WEO/ZycoTherm improved the asphalt resistance to rutting at
elevated temperatures in both conditions i.e., before and after short-term aging. In addition, the
findings revealed ZycoTherm /WEO compound yielded the best performance to improve the
minimal-temperature cracking resistance of the SBR-modified binder, resulting in lower short-
term aging temperatures. In summary, this study highlights the necessity of lowering prepara-tion
temperatures in asphalt mixes containing SBR to enhance binder resistance to rutting and
cracking and reduce susceptibility to oxidation during short-term aging.
Research Interests:
Traffic jams occur when a volume of traffic influx produces a demand for space more significant than the road allows. Numerical field data addressing vehicle counts and statistical computer simulations are vital tools in determining a... more
Traffic jams occur when a volume of traffic influx produces a demand for space more significant than the road allows. Numerical field data addressing vehicle counts and statistical computer simulations are vital tools in determining a road's serviceability and traffic level. Both have been utilized in this study. The primary objectives of this study are to conduct a comprehensive analysis of the traffic flow, measure the Level of Service (LOS), travel time, degree of saturation, delay time, and articulate a strategy to reduce traffic congestion at roundabouts. The study unequivocally concluded that the LOS at the eastern entrance is F level. The data on the number of vehicles that pass through the roundabout at the eastern entrance of Benghazi were recorded during the peak hours from (12:00 to 1:30) p.m. The mixed traffic stream was then converted to passenger car units (PCU) to be homogenously equivalent. The results of the systematic analysis of the gathered data indicate that the roundabout at Benghazi's eastern entrance requires further development to alleviate the dire traffic conditions. To run an accurate simulation, the existing road layout was surveyed using surveying instrumentation, and the results were used to build a model. Acceleration and deacceleration lanes were proposed to improve the roundabout performance and reduce congestion. Then, the roundabout expansion proposal was introduced into the simulation to study its effectiveness in reducing traffic jams. The data were analysed and tested using SIDRA software. The Level of Service at the roundabout's lanes showed tremendous improvement as the Level of Service varied from A to B levels compared to the current LOS level of F.
Research Interests:
The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several... more
The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several pieces of research have been done to show the significance of these waste materials on the strength of the soil. This research aims to focus on the impact of granite powder on the behavior of the soil subjected to loading. Therefore, soils blended with several amounts of granite powder i.e. 4%, 8%, 12%, 16%, and 20% of the total weight were examined. The CBR, compaction and direct shear tests were executed to evaluate the performance of the untreated and treated soils. The findings proved that adding granite dust increased noticeably the shear strength, CBR and dry density of the soils. It was found that an addition of 8% granite dust to the natural soil yields the most appropriate results among other contents of granite dust. Hence, it is concluded tha...
Research Interests:
The practice of using waste materials to modify the properties of poor soils has become increasingly important in geotechnical engineering. In recent years, much research has been devoted to the effect of this waste material on soil... more
The practice of using waste materials to modify the properties of poor soils has become increasingly important in geotechnical engineering. In recent years, much research has been devoted to the effect of this waste material on soil properties. This study aims to address the influence of marble dust powder on the performance of subgrade. Thus, soils mixed with different percentages of marble dust were tested. The CBR test and modified proctor have been used to evaluate the performance of the soils mixed with marble dust. The statistical analysis illustrated that marble dust significantly enhanced the properties of the soils. The study concludes that an addition of 10% of marble dust to untreated (control) soils yields the most satisfactory results among other percentages of marble dust. The study recommends the use of marble dust in geotechnical construction.
Research Interests:
Asphalt recycling technology with a high content of reclaimed asphalt pavement (RAP) is becoming more important as the price of paving materials rises and sustainable development and environmental conservation rules become more rigorous.... more
Asphalt recycling technology with a high content of reclaimed asphalt pavement (RAP) is becoming more important as the price of paving materials rises and sustainable development and environmental conservation rules become more rigorous. Nevertheless, road authorities in numerous countries still prohibit the utilisation of RAP in asphalt mixes due to the negative impacts of RAP on the performance of asphalt mixtures. Consequently, different rejuvenators have been introduced to reinstate the original attributes of aged asphalt to resolve this issue. This study incorporated vacuum residue (VR) into mixtures with 40% RAP. The physical, rheological, and mechanical traits of the resultant samples were assessed. The results show that the 7.5% VR rejuvenator minimised the RAP asphalt ageing impact. Furthermore, the rejuvenating agent demonstrated physical and rheological rehabilitative benefits for the aged asphalt. The mechanical attributes of the rejuvenated samples were also enhanced co...
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The increase in the amount of reclaimed asphalt pavement (RAP) and environmental concerns for bitumen production have contributed to the use of RAP in road construction and maintenance. The use of higher than 15% of RAP adversely affects... more
The increase in the amount of reclaimed asphalt pavement (RAP) and environmental concerns for bitumen production have contributed to the use of RAP in road construction and maintenance. The use of higher than 15% of RAP adversely affects the physical and rheological properties of the asphalt binder and the mechanical properties of mixtures. Therefore, the use of bitumen and asphalt mixture improver were necessary to reduce the negative effects generated with the use of RAP. This paper aims to study the effect of fiberglass (FG) (0.5%, 1.0%, 1.5%, and 2%) on the mechanical properties of asphalt concrete containing 25%, 50% RAP and 9% waste engine oil. The performance of RAP asphalt mixtures incorporated with FG was evaluated using the Marshall stability test, moisture susceptibility test, and immersion wheel rutting test. The results indicated that the use of FG and RAP materials to rejuvenated asphalt mixtures resulted in an increase in the values of Marshall stability and rutting r...
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Evaluating the performance of rejuvenated asphalt mixes is crucial for pavement design and construction, as using a rejuvenator not only boosts recycling and contributes to positive effects on the environment but also increases the... more
Evaluating the performance of rejuvenated asphalt mixes is crucial for pavement design and construction, as using a rejuvenator not only boosts recycling and contributes to positive effects on the environment but also increases the sensitivity to rutting and moisture. This study was executed to evaluate the effect of a warm mix asphalt (WMA) antistripping agent, namely nano-ZycoTherm, on the moisture-induced damage and rutting potential of asphalt mixtures containing 30% and 60% aged (RAP) binder and rejuvenated with 12% waste engine oil (WEO). For this purpose, the rutting resistance of asphalt mixes in wet and dry conditions was examined utilizing a loaded wheel tracker. In addition, the impacts of moisture on the performance of the mixtures were evaluated using different experiments, such as modified Lottman (AASHTO T283), resilient modulus, dynamic creep, aggregate coating and wheel tracking tests. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric (TG) analysi...
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The wide application of reclaimed asphalt pavement (RAP) is hindered due to the highly brittle nature of the material, which contributes a major factor towards cracking-related distresses. While the utilisation of rejuvenating agents has... more
The wide application of reclaimed asphalt pavement (RAP) is hindered due to the highly brittle nature of the material, which contributes a major factor towards cracking-related distresses. While the utilisation of rejuvenating agents has been shown to enhance the flexibility of RAP, they also trigger certain negative effects on the performance of asphalt mixtures. In view of this, potential rejuvenators should be able to alter the rheological properties of asphalts to limit fatigue issues and enhance the potential of low-temperature cracking. Therefore, this study aimed to investigate the possibility of extraction and characterisation of maltene from virgin asphalt (VA) as a potential rejuvenating agent in RAP. Several physicochemical characteristics were examined, including density, viscosity, gas chromatography–mass spectrometry (GC–MS), Fourier-transform infrared (FTIR) spectroscopy, CHNS elemental analysis, and energy dispersive X-ray (EDX) analysis. Finally, the stiffness modul...
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The concept of sustainability is considered essential in the development of the asphalt mixtures industry, due to its economic and environmental benefits. This study attempts to highlight the potential benefits of sustainability using... more
The concept of sustainability is considered essential in the development of the asphalt mixtures industry, due to its economic and environmental benefits. This study attempts to highlight the potential benefits of sustainability using Reclaimed Asphalt Pavement (RAP). It reviews previous studies conducted on RAP to obtain the most important characteristics in how to use the optimal content of RAP and its effect on some basic properties such as resilient modulus, susceptibility to moisture, permanent deformation, and fatigue. This study mainly focuses on the advantages of using RAP materials in hot mix asphalt (HMA). The results indicated that adding 30% of RAP to virgin asphalt mixtures gives the best performance in terms of the most studied characteristics.
Research Interests:
In recent decades, escalating traffic volumes initiate asphalt pavements revealed to larger stresses, which can create premature distresses. To enhance the resistance to distresses, modification of the asphalt mixtures has been studied... more
In recent decades, escalating traffic volumes initiate asphalt pavements revealed to larger stresses, which can create premature distresses. To enhance the resistance to distresses, modification of the asphalt mixtures has been studied extensively. The objective of this paper is to evaluate the performance of asphalt pavement made with various bitumen types and also different thicknesses. The bitumen types used were conventional asphalt (Ac 60-70) and polymer modified asphalt (PG 76-22). The thickness of asphalt samples tested was 70, 80, and 90 mm. In this study, Accelerated Pavement Testing (APT) was conducted to evaluate the rut depth in the surface of the pavement. The experiment was run up to 20,000 cycles. The results revealed polymer has a significant effect on pavement resistance to rutting. The resistance can be increased by up to 30%. In addition, the rutting occurred rapidly for the first 3,000 cycles. Beyond 3,000, the deformation is increased slowly. On the other side,...
Research Interests:
The practice of crumb rubber derived from scrap tires to modify the mechanical properties of bituminous mixtures has become increasingly important in road engineering. In recent years, much research has been devoted to the influence of... more
The practice of crumb rubber derived from scrap tires to modify the mechanical properties of bituminous mixtures has become increasingly important in road engineering. In recent years, much research has been devoted to the influence of this waste material on pavement performance. This paper aims to address the influence of crumb rubber (CR) polymers on the performance of asphalt pavements. Thus, asphalt mixtures with varying percentages of CR mixed by the wet process were tested. The statistical analysis revealed that crumb rubber significantly increased the stiffness modulus, rutting resistance, and pavement resistance to moisture damage. The study concludes that an addition of 20% to 24% of crumb rubber modifiers to conventional asphalt mixture yields the most satisfactory results among other percentages of CR polymers. The study recommends the use of crumb rubber in pavement construction.
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Composite traffic control mechanisms at intersections are normally made up of two or more traffic control devices; for example, roundabout and traffic signals combined or if you like, traffic signal and one way flow combined. Roundabouts... more
Composite traffic control mechanisms at intersections are normally made up of two or more traffic control devices; for example, roundabout and traffic signals combined or if you like, traffic signal and one way flow combined. Roundabouts work on the principle of circulation and entry flows; whereas signalised intersections rely on staging or phasing for effectiveness. Safety at roundabouts is enhanced by limiting circulating speeds and this is achieved in geometric design by entry path curvature. While control strategy of traffic signal is flexible; it hinges on vehicle actuation or fixed time operation. However, there are some vexing traffic safety issues worth considering at signalised roadways; for example, in the event of signal breakdown or malfunction, how would such intersections cope with gridlock; what are the delay trade-offs for installing a standard roundabout at existing signalised intersections or vice versa. As a consequence, delay studies were carried out at a signal...
Research Interests:
Composite traffic control mechanisms at intersections are normally made up of two or more traffic control devices; for example, roundabout and traffic signals combined or if you like, traffic signal and one way flow combined. Roundabouts... more
Composite traffic control mechanisms at intersections are normally made up of two or more traffic control devices; for example, roundabout and traffic signals combined or if you like, traffic signal and one way flow combined. Roundabouts work on the principle of circulation and entry flows; whereas signalised intersections rely on staging or phasing for effectiveness. Safety at roundabouts is enhanced by limiting circulating speeds and this is achieved in geometric design by entry path curvature. While control strategy of traffic signal is flexible; it hinges on vehicle actuation or fixed time operation. However, there are some vexing traffic safety issues worth considering at signalised roadways; for example, in the event of signal breakdown or malfunction, how would such intersections cope with gridlock; what are the delay trade-offs for installing a standard roundabout at existing signalised intersections or vice versa. As a consequence, delay studies were carried out at a signal...
Research Interests:
Epoxy composites reinforced with recycled cellulose fibre (RCF) have been synthesized and characterized. The reinforcement by RCF has resulted in a significant increase in the strain at break, fracture toughness and impact toughness but... more
Epoxy composites reinforced with recycled cellulose fibre (RCF) have been synthesized and characterized. The reinforcement by RCF has resulted in a significant increase in the strain at break, fracture toughness and impact toughness but moderate increase in flexural strength and flexural modulus. The effect of seawater soaking on the flexural and impact properties has also been investigated. The micromechanisms of toughening and crack-tip failure processes are identified and discussed in the light of observed microstructures from in-situ and ex-situ fracture.
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Soft soils such as clay soils, mostly if they comprise swelling minerals may produce great damage to structures, particularly when these soils are exposed to wetting and drying situations. The geotechnical properties of soft soils could... more
Soft soils such as clay soils, mostly if they comprise swelling minerals may produce great damage to structures, particularly when these soils are exposed to wetting and drying situations. The geotechnical properties of soft soils could be enhanced by utilizing chemical additives. In this paper, granite waste dust was used to adjust the properties of clay soils. This paper investigates the effect of granite rock dust on the geotechnical properties of soft soil. The particle size distribution, Atterberg limits, compaction, California bearing ratio (CBR) and direct shear strength characteristics of the soil when blended with various percentages of granite dust were evaluated. The findings show a great increase in the maximum dry density, optimum water content, direct shear strength and CBR with increasing the amount of granite dust. The best results obtained for CBR values were when the soils mixed with 8% granite dust. Although these findings indicate great improvement in the geotech...
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The purpose of this paper is to determine the quality of highway service at signalized roundabout. Consequence, delay studies were carried out at a signalized intersection with composite traffic control mechanism. Bearing in mind that... more
The purpose of this paper is to determine the quality of highway service at signalized roundabout. Consequence, delay studies were carried out at a signalized intersection with composite traffic control mechanism. Bearing in mind that composite ...
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Asphalt block pavement is an innovative alternative to asphalt pavements. This study investigated the performance of asphalt paving blocks with a number of variables: block thickness, bitumen types and joint width between blocks. The... more
Asphalt block pavement is an innovative alternative to asphalt pavements. This study investigated the performance of asphalt paving blocks with a number of variables: block thickness, bitumen types and joint width between blocks. The effect of dynamic and static loads and their transfer from one block to another on the behaviour of asphalt block pavements were studied. Asphalt blocks were laid on sand bedding, but direct laying on a base course was also investigated. The experiments conducted in the laboratory were push-in test, pull-out test, and accelerated trafficking test. Two types of bitumen were used as binder to produce asphalt blocks: normal bitumen (60/70) and modified bitumen (PG 76) and different block thicknesses: 70 mm, 80 mm, and 90 mm. Asphalt blocks were laid in stretcher bond with various joint widths: no joint spacing, 2 mm, and 3 mm. The instruments of the push-in test and pull-out test were constructed within a steel box of 1.0 metre square; the push-in vertical...
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The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several... more
The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several pieces of research have been done to show the significance of these waste materials on the strength of the soil. This research aims to focus on the impact of granite powder on the behavior of the soil subjected to loading. Therefore, soils blended with several amounts of granite powder i.e. 4%, 8%, 12%, 16%, and 20% of the total weight were examined. The CBR, compaction and direct shear tests were executed to evaluate the performance of the untreated and treated soils. The findings proved that adding granite dust increased noticeably the shear strength, CBR and dry density of the soils. It was found that an addition of 8% granite dust to the natural soil yields the most appropriate results among other contents of granite dust. Hence, it is concluded tha...
Research Interests:
Reclaimed asphalt pavement (RAP) has received much attention recently due to its increased use in hot mix asphalt (HMA) pavements to enhance pavement sustainability. The use of aged asphalt in RAP, which is highly oxidised and has lost... more
Reclaimed asphalt pavement (RAP) has received much attention recently due to its increased use in hot mix asphalt (HMA) pavements to enhance pavement sustainability. The use of aged asphalt in RAP, which is highly oxidised and has lost its properties due to exposure to traffic loads and climatic conditions throughout its lifespan, can cause asphalt mixtures to stiffen and embrittle, thus negatively affecting the behaviour of asphalt mixtures. This issue may be resolved by including rejuvenating agents that can restore both physical and rheological properties of aged asphalt by increasing maltene fractions and decreasing asphaltene. However, the high restoration capacity of any kind of rejuvenating agent does not assure the durability of restored aged asphalt. This study explored the performance and durability of rejuvenated asphalt mixtures embedded with several types of rejuvenators identified from the extensive literature review. The study serves as a significant reference to pred...
Research Interests:
the practice of using waste materials to modify the properties of poor soils has become increasingly important in geotechnical engineering. In recent years, much research has been devoted to the effect of this waste material on soil... more
the practice of using waste materials to modify the properties of poor soils has become increasingly important in geotechnical engineering. In recent years, much research has been devoted to the effect of this waste material on soil properties. This study aims to address the influence of marble dust powder on the performance of subgrade. Thus, soils mixed with different percentages of marble dust were tested. The CBR test and modified proctor have been used to evaluate the performance of the soils mixed with marble dust. The statistical analysis illustrated that marble dust significantly enhanced the properties of the soils. The study concludes that an addition of 10% of marble dust to untreated (control) soils yields the most satisfactory results among other percentages of marble dust. The study recommends the use of marble dust in geotechnical construction.
The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several... more
The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several pieces of research have been done to show the significance of these waste materials on the strength of the soil. This research aims to focus on the impact of granite powder on the behavior of the soil subjected to loading. Therefore, soils blended with several amounts of granite powder i.e. 4%, 8%, 12%, 16%, and 20% of the total weight were examined. The CBR, compaction and direct shear tests were executed to evaluate the performance of the untreated and treated soils. The findings proved that adding granite dust increased noticeably the shear strength, CBR and dry density of the soils. It was found that an addition of 8% granite dust to the natural soil yields the most appropriate results among other contents of granite dust. Hence, it is concluded that the granite dust has good potential to be used as an additive for improving the engineering properties of clayey soil.
Research Interests:
In recent decades, escalating traffic volumes initiate asphalt pavements revealed to larger stresses, which can create premature distresses. To enhance the resistance to distresses, modification of the asphalt mixtures has been studied... more
In recent decades, escalating traffic volumes initiate asphalt pavements revealed to larger stresses, which can create premature distresses. To enhance the resistance to distresses, modification of the asphalt mixtures has been studied extensively. The objective of this paper is to evaluate the performance of asphalt pavement made with various bitumen types and also different thicknesses. The bitumen types used were conventional asphalt (Ac 60-70) and polymer modified asphalt (PG 76-22). The thickness of asphalt samples tested was 70, 80, and 90 mm. In this study, Accelerated Pavement Testing (APT) was conducted to evaluate the rut depth in the surface of the pavement. The experiment was run up to 20,000 cycles. The results revealed polymer has a significant effect on pavement resistance to rutting. The resistance can be increased by up to 30%. In addition, the rutting occurred rapidly for the first 3,000 cycles. Beyond 3,000, the deformation is increased slowly. On the other side, the results showed that as the HMA thickness increases as the resistance to deformation increases. We, therefore, can conclude that adding particles of polymer to HMA could improve the structural performance of pavement i.e. rutting resistance and reduce the thickness of the surface
Research Interests:
Soft soils such as clay soils, mostly if they comprise swelling minerals may produce great damage to structures, particularly when these soils are exposed to wetting and drying situations. The geotechnical properties of soft soils could... more
Soft soils such as clay soils, mostly if they comprise swelling minerals may produce great damage to structures, particularly when these soils are exposed to wetting and drying situations. The geotechnical properties of soft soils could be enhanced by utilizing chemical additives. In this paper, granite waste dust was used to adjust the properties of clay soils. This paper investigates the effect of granite rock dust on the geotechnical properties of soft soil. The particle size distribution, Atterberg limits, compaction, California bearing ratio (CBR) and direct shear strength characteristics of the soil when blended with various percentages of granite dust were evaluated. The findings show a great increase in the maximum dry density, optimum water content, direct shear strength and CBR with increasing the amount of granite dust. The best results obtained for CBR values were when the soils mixed with 8% granite dust. Although these findings indicate great improvement in the geotechnical parameters of clayey soils, the higher strength established is not enough for the enhanced soil to be utilized as a base material in the construction of heavily-trafficked flexible pavements. However, this modified material can be used as a base material for moderate traffic roads and as a sub-base material for high traffic roads.
Research Interests:
the practice of using waste materials to modify the properties of poor soils has become increasingly important in geotechnical engineering. In recent years, much research has been devoted to the effect of this waste material on soil... more
the practice of using waste materials to modify the properties of poor soils has become increasingly important in geotechnical engineering. In recent years, much research has been devoted to the effect of this waste material on soil properties. This study aims to address the influence of marble dust powder on the performance of subgrade. Thus, soils mixed with different percentages of marble dust were tested. The CBR test and modified proctor have been used to evaluate the performance of the soils mixed with marble dust. The statistical analysis illustrated that marble dust significantly enhanced the properties of the soils. The study concludes that an addition of 10% of marble dust to untreated (control) soils yields the most satisfactory results among other percentages of marble dust. The study recommends the use of marble dust in geotechnical construction.
The practice of crumb rubber derived from scrap tires to modify the mechanical properties of bituminous mixtures has become increasingly important in road engineering. In recent years, much research has been devoted to the influence of... more
The practice of crumb rubber derived from scrap tires to modify the mechanical properties of bituminous mixtures has become increasingly important in road engineering. In recent years, much research has been devoted to the influence of this waste material on pavement performance. This paper aims to address the influence of crumb rubber (CR) polymers on the performance of asphalt pavements. Thus, asphalt mixtures with varying percentages of CR mixed by the wet process were tested. The statistical analysis revealed that crumb rubber significantly increased the stiffness modulus, rutting resistance, and pavement resistance to moisture damage. The study concludes that an addition of 20% to 24% of crumb rubber modifiers to conventional asphalt mixture yields the most satisfactory results among other percentages of CR polymers. The study recommends the use of crumb rubber in pavement construction.
the use of crumb rubbermodifiersby dry process is notused extensively in asphalt applicationsasthe wet process.This study aims to investigate the effect of crumb rubber modifiers on properties and performance of asphalt... more
the use of crumb rubbermodifiersby dry process is notused extensively in asphalt applicationsasthe wet process.This study aims to investigate the effect of crumb rubber modifiers on properties and performance of asphalt mix by dry process. Thus, aset of asphalt mixtures containing various percentages of crumb rubber modifiers mixed by the dry process were tested. Moreover, the effect of modifying conventional asphalt mixture with crumb rubber polymers was evaluated. In addition, a comparative assessment was made to evaluate rubberized mixtures and unmodified bitumen mixture. The mixtures were assessedby using the Marshall Stabilitytest, the wheel tracking test and themoisture susceptibility test. The study revealed that an addition of crumb rubber modifiers to conventional asphalt mixture enhances pavement stability and increases its resistance to rutting and moisture damage. The study concludes thatan addition of 2% of CR to unmodified AC16 gives the most satisfactory results among other rubberized mixtures.
Research Interests:
Asphalt blocks have been occasionally used around the world as a road pavement, but there have been very limited studies being done to evaluate the effect of joint width (spacing) between the blocks on the structural performance of... more
Asphalt blocks have been occasionally used around the world as a road pavement, but there have been
very limited studies being done to evaluate the effect of joint width (spacing) between the blocks on the structural
performance of asphalt paving blocks. This study explains the experimental study to assess the performance and
properties of asphalt paving blocks laid with different joint widths between the blocks i.e., 0, 2 and 3 mm,
respectively. A total of 250 asphalt paving blocks was manufactured and tested in the laboratory to ascertain the
density, air voids, the compressive strength and the rut depth and displacement occurred in asphalt paving block.
The design compressive load of single asphalt paving block is 166 kN. The test results showed that the joint width
plays a vital role on the performance of asphalt block pavement. Asphalt paving blocks were laid as closely in
contact as possible (0 mm) yields the best structural performance.
very limited studies being done to evaluate the effect of joint width (spacing) between the blocks on the structural
performance of asphalt paving blocks. This study explains the experimental study to assess the performance and
properties of asphalt paving blocks laid with different joint widths between the blocks i.e., 0, 2 and 3 mm,
respectively. A total of 250 asphalt paving blocks was manufactured and tested in the laboratory to ascertain the
density, air voids, the compressive strength and the rut depth and displacement occurred in asphalt paving block.
The design compressive load of single asphalt paving block is 166 kN. The test results showed that the joint width
plays a vital role on the performance of asphalt block pavement. Asphalt paving blocks were laid as closely in
contact as possible (0 mm) yields the best structural performance.
Research Interests:
Asphalt paving blocks have been known in some places around the world, but there have been very limited research being conducted to assess the influence of block thickness on the structural performance of asphalt paving blocks. This study... more
Asphalt paving blocks have been known in some places around the world, but there have been very
limited research being conducted to assess the influence of block thickness on the structural performance of asphalt
paving blocks. This study describes the experimental study to evaluate the performance and properties of asphalt
paving blocks placed with different block thicknesses i.e., 70, 80 and 90 mm, respectively. A number of 250 asphalt
paving blocks was produced and examined in the laboratory to determine the density, air voids, the compressive
load and the rut depth and displacement occurred in the surface of asphalt paving block. The results exhibited that
the resistance of asphalt paving block to static loading increased as the block thickness increased. Moreover, the
elastic deformation was affected significantly by increasing the block thickness. Meanwhile, the displacement of
asphalt block from the pavement was slightly influenced by the block thickness
limited research being conducted to assess the influence of block thickness on the structural performance of asphalt
paving blocks. This study describes the experimental study to evaluate the performance and properties of asphalt
paving blocks placed with different block thicknesses i.e., 70, 80 and 90 mm, respectively. A number of 250 asphalt
paving blocks was produced and examined in the laboratory to determine the density, air voids, the compressive
load and the rut depth and displacement occurred in the surface of asphalt paving block. The results exhibited that
the resistance of asphalt paving block to static loading increased as the block thickness increased. Moreover, the
elastic deformation was affected significantly by increasing the block thickness. Meanwhile, the displacement of
asphalt block from the pavement was slightly influenced by the block thickness
Research Interests:
The purpose of study is to assess and compare level of service at an intersection with and without traffic signal control. Volumes, turning proportion, intersection geometrics and headway data have been obtained by survey. Data collected... more
The purpose of study is to assess and compare level of service at an intersection with and without traffic signal control. Volumes, turning proportion, intersection geometrics and headway data have been obtained by survey. Data collected have been used to estimate demand and saturation flows, intersection signal timings, delays and level of service. The collected data have been analyzed by using manual calculation and computer software (ARCADY and TRANSYT). ARCADY has been used to estimate delays at the roundabout while TRANSYT has been used to optimize traffic signal timings and estimate delays. From results, the LOS for the signalized intersection is categorized as LOS C. while LOS for roundabout is categorized as LOS A. The results showed that the roundabout gives better performance. Hence, LOS for the intersection has been increased and improved from LOS D to better quality performance which is LOS A.
Research Interests:
The purpose of this paper is to determine the quality of highway service at signalized roundabout. Consequence, delay studies were carried out at a signalized intersection with composite traffic control mechanism. Bearing in mind that... more
The purpose of this paper is to determine the quality of highway service at signalized roundabout. Consequence, delay studies were carried out at a signalized intersection with composite traffic control mechanism. Bearing in mind that composite traffic control mechanisms are two or more traffic control devices, data for single and composite signalized intersections were analysed and compared. Results show a slightly improved level of service with roundabout, more importantly significant reduction in conflicting movement and gridlock was achieved when the traffic signals were switched off. The study concluded that signalized roundabouts have significant influence on vehicular conflict, gridlock that may reduce red light running.
Research Interests:
Composite traffic control mechanisms at intersections are normally made up of two or more traffic control devices; for example, roundabout and traffic signals combined or if you like, traffic signal and one way flow combined. Roundabouts... more
Composite traffic control mechanisms at intersections are normally made up of two or more traffic control devices; for example, roundabout and traffic signals combined or if you like, traffic signal and one way flow combined. Roundabouts work on the principle of circulation and entry flows; whereas signalised intersections rely on staging or phasing for effectiveness. Safety at roundabouts is enhanced by limiting circulating speeds and this is achieved in geometric design by entry path curvature. While control strategy of traffic signal is flexible; it hinges on vehicle actuation or fixed time operation. However, there are some vexing traffic safety issues worth considering at signalised roadways; for example, in the event of signal breakdown or malfunction, how would such intersections cope with gridlock; what are the delay trade-offs for installing a standard roundabout at existing signalised intersections or vice versa. As a consequence, delay studies were carried out at a signalised intersection during peak period in Skudai, Malaysia. Delay data for single and composite signalised intersections were analysed and compared. Results show a slightly improved level of service with roundabout, more importantly significant reduction in conflicting movement and gridlock was achieved when the traffic signals were switched off. The study concluded that at signalised intersections, composite traffic control mechanisms have significant influence on vehicular conflict, gridlock and red light running compared with single control devices.