Several road pavement distresses are related to rheological bitumen properties. Rutting and fatig... more Several road pavement distresses are related to rheological bitumen properties. Rutting and fatigue cracking are the major distresses that lead to permanent failures in pavement construction. Inluence of crumb rubber modiier (CRM) on rheological properties of bitumen binder such as improvement of high and intermediate temperatures is investigated in the binder's fatigue and rutting resistance through physical-rheological changes in this research. he bitumen binders were aged by rolling thin ilm oven (RTFOT) to simulate short-term aging and pressure aging vessel (PAV) to simulate long-term aging. he efects of aging on the rheological and physical properties of bitumen binders were studied conducting dynamic shear rheometer test (DSR), Brookield viscometer test, sotening point test, and penetration test. he results showed that the use of rubberised bitumen binder reduces the aging efect on physical and rheological properties of the bitumen binder as illustrated through lower aging index of viscosity, lower aging index of * /sin , and an increase in Tan with crumb rubber modiier content increasing, indicating that the crumb rubber might improve the aging resistance of rubberised bitumen binder. In addition, the results showed that the sotening point increment (Δ) and penetration aging ratio (PAR) of the rubberised bitumen binder decreased signiicantly due to crumb rubber modiication. Furthermore, the higher crumb rubber content, the lower * sin ater PAV aging, which led to higher resistance to fatigue cracking bitumen.
Pakistan Journal of Engineering and Applied Sciences, Jun 22, 2016
Permanent deformation of asphaltic concrete depends on temperature, rate of loading and state of ... more Permanent deformation of asphaltic concrete depends on temperature, rate of loading and state of stress and significantly increases above 40 o C. The deformation behavior of finer to coarser hot-mix asphalt (HMA) mixtures was investigated in the laboratory by varying stress level from 100 to 500 kPa at 40 o C & 55 o C. Uniaxial repeated creep and wheel tracker tests were carried out at the specified conditions and the results were correlated to seek relationships between test methods. Subsequently, shift factors and a correlation between the test methods are proposed to guide pavement engineers in the selection of rut resistant mixtures in future. The results show that intercept coefficients vary in a narrow range and an average shift of 0.48 makes both the tests data on a straight line. Uniaxial repeated load strain test do not show a clear ranking of the mixtures at the specified temperatures and the stress conditions. The slope of linear relationship between the tests reduces with an increase in temperature and stress level.
Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. T... more Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. The range of slope coefficient (K2), obtained from fatigue equation is from 2.03 to 4.25. A reasonable relationship exits between the slope and intercept coefficient of fatigue equation. Stone dust as filler improves the fatigue performance of asphalt mix.
International Journal of Pavement Engineering, Dec 18, 2020
This research study utilized a Thermal Cycler to simulate the field aging conditions and compared... more This research study utilized a Thermal Cycler to simulate the field aging conditions and compared with standard laboratory aging methods. The Thermal Cycler intends to simulate asphalt binder aging under specific environmental conditions. The main purpose of the study is to assess the aging potential in the binder during the thermo-oxidation process. Sulphur, Methane Phosphorus Compound, Elvaloy, Multiwalled Carbon nanotubes, Carbon black nanoparticles, and Graphene nanoplatelets were used and their influence was studied on virgin binder considering their aging sensitivities. Scanning Electron Microscope, Dynamic shear rheometer, and Fourier Transform Infrared spectroscopy were used to study dispersion, rheology, and chemical changes in the binder, respectively. The results showed that aging increases the oxidation process causing more oxygen content formation. The amount of aging in PAV was equivalent to 28 days aged in Thermal Cycler. At higher temperatures, a substantial improvement in Thermal Cyclic aging was observed and around 6-8 h of aging at 110°C produced the same effect as that in PAV. Graphene nanoplatelets modified bitumen with the least Carbonyl and Sulfoxide index is relatively effective to retard aging rate. Sulphur and Methane Phosphorous Compound are relatively more sensitive to thermo-oxidative aging than the rest of the modified blends.
Large quantities of waste glass generated around the world are a source of environmental pollutio... more Large quantities of waste glass generated around the world are a source of environmental pollution and burden on landfill capacities. This glass can be brought in use by incorporating it in asphalt pavements as a replacement for aggregate particles. This research aims at evaluation of various structural, functional and durability parameters of asphalt containing waste borosilicate glass (BSG). Optimum binder content and volumetric characters were accessed using Marshall mix design method, wheel tracking test was used to evaluate the rutting resistance, and four-point beam fatigue test was used to measure the resistance against fatigue cracking. Deformation characteristics were studied using dynamic modulus test, and British pendulum test and aggregate polishing value test were used to study the skid resistance. Finally, moisture damage was evaluated using rolling bottle test. The results revealed that increasing BSG content reduces the optimum binder content requirements of final mi...
International Journal for Research in Applied Science and Engineering Technology
The asphalt binder must be modified to extend the service life of flexible pavements. As the temp... more The asphalt binder must be modified to extend the service life of flexible pavements. As the temperature outside drops, the pavements shrink and develop internal stresses. The pavement may break if this contraction happens quickly enough because it won't have time to relax these stresses. Due to the cracking's orientation with respect to the flow of traffic, this form of fracture is frequently referred to as a "thermal crack" or a "transverse crack.". The purpose of this article is to assess how adding nanoclay to asphalt binder changes its performance at low temperatures. The stiffness and stress relaxation time of a material can be measured with a Bending Beam Rheometer (BBR). It is ideal for asphalt binders to be able to release built-up tensions and not become overly stiff at low temperatures. The BBR test was carried out to investigate the low-temperature behaviour of asphalt binder. Test samples were prepared by adding varying nanoclay content and test temperatures were defined. Three small beams of each percentage were prepared and tested after conditioning at defined test temperatures. Results of modified asphalt binder were assessed and contrasted to unmodified asphalt binder to optimize the nanoclay content. The study revealed that increment in nanoclay amount increased the creep stiffness of asphalt binder. İt was concluded from the study that improvement of creep stiffness played a key role towards the low-temperature performance. The maximum increase in creep stiffness was found by the addition of 5 % nanoclay at-16 °C.
International Journal for Research in Applied Science and Engineering Technology
The use of modified asphalt binders in hot-mix asphalt has steadily increased over the past sever... more The use of modified asphalt binders in hot-mix asphalt has steadily increased over the past several decades. Mixing and compaction temperatures of an asphalt binder plays a vital role in the production and placement of asphalt mixes but there are no standards for mixing and compaction temperatures for modified asphalt binder especially with Organophilic nanoclay. In this study the effect of nanoclay modified binder on mixing and compaction temperatures of asphalt mixture was observed using conventional test for asphalt mixture-softening point test, penetration test and rotational viscometer test. Five different percentages i-e 3, 3.5, 4, 4.5 and 5% of Nanoclay (modifier) are selected for three different binders (ARL 60/70, ARL 80/100 & NRL 60/70). Six different samples for each binder are prepared and conventional testing is carried out using standard procedures. With an increase in the percentage of Nanoclay the softening point values and viscosity values increases, similarly the penetration values decrease. The mixing temperature range is 155-165°C and compaction temperature range is 135-145 °C to achieve maximum density in the field.
International Journal for Research in Applied Science and Engineering Technology
Material that makes bound with bitumen known as bituminous material. For determination of propert... more Material that makes bound with bitumen known as bituminous material. For determination of properties of bituminous material various field test and techniques are used which are time consuming and have expensive material cost. To avoid such problems, techniques are required which can provide basic input parameters for materials models to be used in MEPDG Level-I pavement design input. The properties of bitumen can be fully described by using both the complex modulus and phase angles. Black Space diagram determines the viscosity, Stiffness, and elasticity by using complex modulus and phase angle and the G* and δ linked to Glover-Rowe concept which defines the two damaging zones that are damage onset and significant cracking. Cole-Cole plot shows the viscous and elastic behaviour of bitumen. Two bitumen grade 40-50 and 60-70 penetration grade and PMB (modified 60-70 with 1.6% elvaloy) were studied at six temperatures of 18, 24,30,36,42 and 48 o C and in a frequency range of 0.01Hz to 100Hz using a DSR (dynamic shear rheometer).
Introduction Kashmir is a resource limited, region of India having its own distinctive regional c... more Introduction Kashmir is a resource limited, region of India having its own distinctive regional challenges, operational limitations and poor accessibility of remote areas to health care. Utilizing smart phones as a medium for providing access to the optimum cardiac care in the remotest of the areas of our region served as a platform for SAVE HEART INITIATIVE (SHI) launched in the form of Social Media Whatsapp Group connecting peripheral hospitals (spokes) in the Kashmir region to experts (Hub). Material and methods SHI, a novel initiative was started voluntarily by a team of cardiologists and physicians. All the government hospitals along with their Emergency (ER) teams were roped in, integrated with expert physicians and cardiologists via whats app based technology creating a virtual cardiac ER facility and a CYBER HUB where teams of experts lended optimum support to all the peripheral hospitals of the region which acted as CYBER SPOKES of the initiative. Simultaneously all the per...
Mehran University Research Journal of Engineering and Technology, 2018
The purpose of research is to model and correlate the laboratory rutting behavior of indigenous a... more The purpose of research is to model and correlate the laboratory rutting behavior of indigenous asphalt mixtures, prior to placing in the field. Extensive laboratory testing was carried out on thirty representative wearing course mixtures using two types of rutting performance tests i.e. CWTT (Cooper Wheel Tracking Tests), and APA (Asphalt Pavement Analyzer) tests. The mixture ranking is consistent for both laboratory performance tests at the tested temperature conditions of 40and 50 o C. Laboratory rutting prediction models have been developed by non-linear regression analysis technique. Significant independent variables involved in the model are temperature, number of passes in case of CWTT or number of cycles in case of APA tests, bitumen penetration value, and Flakiness index of coarse aggregates fraction. A strong relationship has been observed between measured and predicted values of rut depth in terms of R 2 value of 0.92 and 0.95 for CWTT and APA tests, respectively. A reasonable empirical quadratic function correlation (R 2 = 0.69) has been developed between rut depth of CWTT and rut depth in APA test.
International Journal of Pavement Engineering, 2020
The permanent deformation of asphalt pavement under similar traffic conditions depends on a numbe... more The permanent deformation of asphalt pavement under similar traffic conditions depends on a number of factors. The factors considered in this study are bitumen source, aggregate source, aggregate g...
Sub grade strength, bitumen content of different structural layers and riding quality of wearing ... more Sub grade strength, bitumen content of different structural layers and riding quality of wearing surface are the most important factors that affect the overall performance of pavement so it is necessary to evaluate the structural behavior and surface characteristics of pavement. The study reveals that runway of new Benazir Bhutto International Airport Islamabad will behave under the heavy loading of aircrafts as per design requirements. This paper documents the Sub grade CBR tests, field density test, different layer's soil classification, profilograph tests and skid resistance tests were performed to find out structural performance of main runway, secondary runway and taxiway and then compared with internationally design standards. From this research, it was concluded that new BBIAP is properly designed according to specifications. IRI values of main, secondary and taxiway are 1.54, 1.99 and 2.96 respectively which are well within internationally accepted values. Optimum asphalt content of bitumen wearing and bitumen base courses are 5.10% and 4.50% respectively when tested on different samples by extraction tests. Loss of stability in Bitumen wearing course and Bitumen Base course are 18% and 9% respectively. It was also concluded that the best Soil used in sub grade of any pavement is A-2-4 with 95% compaction achieved. Because A-2-4 soil can bear maximum load with respect to other groups soil, it is considered to be very effective while preparing sub grade in any runway pavement. From this research, it was also concluded that the factor of percentage of bitumen is dominating factor in the behavior of resilient modulus at a certain limit , as we increase the percentage of bitumen resilient modulus increases and vice versa. After a certain limit resilient modulus decreases by increasing bitumen content.
Highway agencies have been using polymers in asphalt binders to reduce rutting-associated distres... more Highway agencies have been using polymers in asphalt binders to reduce rutting-associated distresses in asphalt pavements. Rheological parameters like complex shear modulus (G*) and phase angle (δ) in the form of G*/Sinδ were used to predict rut resistance of asphalt binders, which have been replaced by a new parameter called non-recoverable creep compliance. The present study investigates the creep compliance of straight run (neat) and polymer-modified asphalt binders, at their high performance grade temperature (58, 64, 70, and 76 °C), using a multi-stress creep recovery test. The test data are used to assess the temperature and stress sensitivity of asphalt binders at different percentages of polymer. Asphalt mixtures, prepared using four asphalt binders, are tested in a wheel tracker to arrive at a relationship between creep compliance and rut resistance of asphalt mixtures. This study has revealed that creep compliance depicts the temperature and stress sensitivity of asphalt binders and asphalt binders’ polymer modification. Based on the stress sensitivity and creep compliance data, the suitability of asphalt binders for different traffic loadings is suggested. The present study proposes a reasonable relationship between creep compliance at 3.2 kPa and rut depth of asphalt mixtures, obtained from a wheel tracker test. This laboratory study may be extended in the future for field validation and development of asphalt mixtures performance-related specifications.
Journal of the Chinese Institute of Engineers, 2014
ABSTRACT The present study evaluates the effect of aggregate gradation with different nominal max... more ABSTRACT The present study evaluates the effect of aggregate gradation with different nominal maximum aggregate sizes on the stiffness, rutting, and fatigue performance of stone mastic asphalt (SMA). These performance parameters are important in mechanistic-empirical pavement design. Four SMA mixes with 4.75, 9.5, 12, and 19 mm nominal maximum size of aggregate in aggregate gradation and a PG 58-22 asphalt binder were designed. Dynamic modulus, wheel tracker, and four-point beam fatigue tests were conducted at different temperatures. A regression model has been utilized using wheel tracker test data, which reveals that rut resistance of SMA increases with an increase of aggregate size in aggregate gradation. Beam fatigue testing and asphalt binder drain down testing indicate that increasing aggregate size in an aggregate gradation decreases fatigue life and increases binder drainage, respectively. This study also reports some relationships between dynamic modulus, wheel tracker rut depth and fatigue life of SMA. A relationship between fatigue coefficients (K1 and K2) obtained from the fatigue curves has also been proposed. Analysis of results indicates that stiffer SMA has lower fatigue life and rut values. Rut resistance and mix stiffness increase with an increase in aggregate size in an aggregate gradation.
ABSTRACT Despite the widespread use of in-place recycling, limited information is available in th... more ABSTRACT Despite the widespread use of in-place recycling, limited information is available in the literature on in situ and laboratory properties of materials placed through in-place recycling. The main objectives of present study were to investigate the in situ recycled material characteristic that includes the potential of asphalt mixtures for permanent deformation, fatigue cracking, and low-temperature cracking, and the effect of a special technique of hot in-place recycling and rejuvenation on asphalt binder rheological properties. To accomplish these objectives, a two-phase experimental program was designed to determine the performance-related parameters of 100% in-place recycled mixtures using one of the in-place recycling techniques in which overlay is not needed. The experimental program included the measurement of mixtures’ mechanical properties and binder rheological properties. The present study revealed that the stiffness of the asphalt mixtures after recycling had increased compared to that before recycling. In general, specimens exhibited a low permanent deformation potential of 2–3 mm after 20,000 loading cycles by using the Hamburg wheel-track test. Stable crack propagation could not be obtained in the fracture tests at −12°C, which indicates the asphalt mixtures’ brittleness at that temperature. Asphalt binder and aggregates, extracted from the samples as collected at various stages of construction, were characterized to assess the effect of the recycling process on mixtures’ properties. Results obtained from the asphalt binder frequency sweep test indicate an increase in the modulus value, which was primarily caused by a heating process at surface layer. This increase in the modulus value of asphalt binder was efficiently compensated by an addition of a rejuvenator. Alternative additives or rejuvenators may also be considered to improve blending and compatibility between the old and new binder, and to reduce the mixture’s stiffness to avoid any possible premature deterioration. The selected rejuvenator should achieve several goals, including complete blending with existing binder and reducing the combined binder performance grade below the binder performance grade of existing mixes.
Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. T... more Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. The range of slope coefficient (K2), obtained from fatigue equation is from 2.03 to 4.25. A reasonable relationship exits between the slope and intercept coefficient of fatigue equation. Stone dust as filler improves the fatigue performance of asphalt mix.
Several road pavement distresses are related to rheological bitumen properties. Rutting and fatig... more Several road pavement distresses are related to rheological bitumen properties. Rutting and fatigue cracking are the major distresses that lead to permanent failures in pavement construction. Inluence of crumb rubber modiier (CRM) on rheological properties of bitumen binder such as improvement of high and intermediate temperatures is investigated in the binder's fatigue and rutting resistance through physical-rheological changes in this research. he bitumen binders were aged by rolling thin ilm oven (RTFOT) to simulate short-term aging and pressure aging vessel (PAV) to simulate long-term aging. he efects of aging on the rheological and physical properties of bitumen binders were studied conducting dynamic shear rheometer test (DSR), Brookield viscometer test, sotening point test, and penetration test. he results showed that the use of rubberised bitumen binder reduces the aging efect on physical and rheological properties of the bitumen binder as illustrated through lower aging index of viscosity, lower aging index of * /sin , and an increase in Tan with crumb rubber modiier content increasing, indicating that the crumb rubber might improve the aging resistance of rubberised bitumen binder. In addition, the results showed that the sotening point increment (Δ) and penetration aging ratio (PAR) of the rubberised bitumen binder decreased signiicantly due to crumb rubber modiication. Furthermore, the higher crumb rubber content, the lower * sin ater PAV aging, which led to higher resistance to fatigue cracking bitumen.
Pakistan Journal of Engineering and Applied Sciences, Jun 22, 2016
Permanent deformation of asphaltic concrete depends on temperature, rate of loading and state of ... more Permanent deformation of asphaltic concrete depends on temperature, rate of loading and state of stress and significantly increases above 40 o C. The deformation behavior of finer to coarser hot-mix asphalt (HMA) mixtures was investigated in the laboratory by varying stress level from 100 to 500 kPa at 40 o C & 55 o C. Uniaxial repeated creep and wheel tracker tests were carried out at the specified conditions and the results were correlated to seek relationships between test methods. Subsequently, shift factors and a correlation between the test methods are proposed to guide pavement engineers in the selection of rut resistant mixtures in future. The results show that intercept coefficients vary in a narrow range and an average shift of 0.48 makes both the tests data on a straight line. Uniaxial repeated load strain test do not show a clear ranking of the mixtures at the specified temperatures and the stress conditions. The slope of linear relationship between the tests reduces with an increase in temperature and stress level.
Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. T... more Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. The range of slope coefficient (K2), obtained from fatigue equation is from 2.03 to 4.25. A reasonable relationship exits between the slope and intercept coefficient of fatigue equation. Stone dust as filler improves the fatigue performance of asphalt mix.
International Journal of Pavement Engineering, Dec 18, 2020
This research study utilized a Thermal Cycler to simulate the field aging conditions and compared... more This research study utilized a Thermal Cycler to simulate the field aging conditions and compared with standard laboratory aging methods. The Thermal Cycler intends to simulate asphalt binder aging under specific environmental conditions. The main purpose of the study is to assess the aging potential in the binder during the thermo-oxidation process. Sulphur, Methane Phosphorus Compound, Elvaloy, Multiwalled Carbon nanotubes, Carbon black nanoparticles, and Graphene nanoplatelets were used and their influence was studied on virgin binder considering their aging sensitivities. Scanning Electron Microscope, Dynamic shear rheometer, and Fourier Transform Infrared spectroscopy were used to study dispersion, rheology, and chemical changes in the binder, respectively. The results showed that aging increases the oxidation process causing more oxygen content formation. The amount of aging in PAV was equivalent to 28 days aged in Thermal Cycler. At higher temperatures, a substantial improvement in Thermal Cyclic aging was observed and around 6-8 h of aging at 110°C produced the same effect as that in PAV. Graphene nanoplatelets modified bitumen with the least Carbonyl and Sulfoxide index is relatively effective to retard aging rate. Sulphur and Methane Phosphorous Compound are relatively more sensitive to thermo-oxidative aging than the rest of the modified blends.
Large quantities of waste glass generated around the world are a source of environmental pollutio... more Large quantities of waste glass generated around the world are a source of environmental pollution and burden on landfill capacities. This glass can be brought in use by incorporating it in asphalt pavements as a replacement for aggregate particles. This research aims at evaluation of various structural, functional and durability parameters of asphalt containing waste borosilicate glass (BSG). Optimum binder content and volumetric characters were accessed using Marshall mix design method, wheel tracking test was used to evaluate the rutting resistance, and four-point beam fatigue test was used to measure the resistance against fatigue cracking. Deformation characteristics were studied using dynamic modulus test, and British pendulum test and aggregate polishing value test were used to study the skid resistance. Finally, moisture damage was evaluated using rolling bottle test. The results revealed that increasing BSG content reduces the optimum binder content requirements of final mi...
International Journal for Research in Applied Science and Engineering Technology
The asphalt binder must be modified to extend the service life of flexible pavements. As the temp... more The asphalt binder must be modified to extend the service life of flexible pavements. As the temperature outside drops, the pavements shrink and develop internal stresses. The pavement may break if this contraction happens quickly enough because it won't have time to relax these stresses. Due to the cracking's orientation with respect to the flow of traffic, this form of fracture is frequently referred to as a "thermal crack" or a "transverse crack.". The purpose of this article is to assess how adding nanoclay to asphalt binder changes its performance at low temperatures. The stiffness and stress relaxation time of a material can be measured with a Bending Beam Rheometer (BBR). It is ideal for asphalt binders to be able to release built-up tensions and not become overly stiff at low temperatures. The BBR test was carried out to investigate the low-temperature behaviour of asphalt binder. Test samples were prepared by adding varying nanoclay content and test temperatures were defined. Three small beams of each percentage were prepared and tested after conditioning at defined test temperatures. Results of modified asphalt binder were assessed and contrasted to unmodified asphalt binder to optimize the nanoclay content. The study revealed that increment in nanoclay amount increased the creep stiffness of asphalt binder. İt was concluded from the study that improvement of creep stiffness played a key role towards the low-temperature performance. The maximum increase in creep stiffness was found by the addition of 5 % nanoclay at-16 °C.
International Journal for Research in Applied Science and Engineering Technology
The use of modified asphalt binders in hot-mix asphalt has steadily increased over the past sever... more The use of modified asphalt binders in hot-mix asphalt has steadily increased over the past several decades. Mixing and compaction temperatures of an asphalt binder plays a vital role in the production and placement of asphalt mixes but there are no standards for mixing and compaction temperatures for modified asphalt binder especially with Organophilic nanoclay. In this study the effect of nanoclay modified binder on mixing and compaction temperatures of asphalt mixture was observed using conventional test for asphalt mixture-softening point test, penetration test and rotational viscometer test. Five different percentages i-e 3, 3.5, 4, 4.5 and 5% of Nanoclay (modifier) are selected for three different binders (ARL 60/70, ARL 80/100 & NRL 60/70). Six different samples for each binder are prepared and conventional testing is carried out using standard procedures. With an increase in the percentage of Nanoclay the softening point values and viscosity values increases, similarly the penetration values decrease. The mixing temperature range is 155-165°C and compaction temperature range is 135-145 °C to achieve maximum density in the field.
International Journal for Research in Applied Science and Engineering Technology
Material that makes bound with bitumen known as bituminous material. For determination of propert... more Material that makes bound with bitumen known as bituminous material. For determination of properties of bituminous material various field test and techniques are used which are time consuming and have expensive material cost. To avoid such problems, techniques are required which can provide basic input parameters for materials models to be used in MEPDG Level-I pavement design input. The properties of bitumen can be fully described by using both the complex modulus and phase angles. Black Space diagram determines the viscosity, Stiffness, and elasticity by using complex modulus and phase angle and the G* and δ linked to Glover-Rowe concept which defines the two damaging zones that are damage onset and significant cracking. Cole-Cole plot shows the viscous and elastic behaviour of bitumen. Two bitumen grade 40-50 and 60-70 penetration grade and PMB (modified 60-70 with 1.6% elvaloy) were studied at six temperatures of 18, 24,30,36,42 and 48 o C and in a frequency range of 0.01Hz to 100Hz using a DSR (dynamic shear rheometer).
Introduction Kashmir is a resource limited, region of India having its own distinctive regional c... more Introduction Kashmir is a resource limited, region of India having its own distinctive regional challenges, operational limitations and poor accessibility of remote areas to health care. Utilizing smart phones as a medium for providing access to the optimum cardiac care in the remotest of the areas of our region served as a platform for SAVE HEART INITIATIVE (SHI) launched in the form of Social Media Whatsapp Group connecting peripheral hospitals (spokes) in the Kashmir region to experts (Hub). Material and methods SHI, a novel initiative was started voluntarily by a team of cardiologists and physicians. All the government hospitals along with their Emergency (ER) teams were roped in, integrated with expert physicians and cardiologists via whats app based technology creating a virtual cardiac ER facility and a CYBER HUB where teams of experts lended optimum support to all the peripheral hospitals of the region which acted as CYBER SPOKES of the initiative. Simultaneously all the per...
Mehran University Research Journal of Engineering and Technology, 2018
The purpose of research is to model and correlate the laboratory rutting behavior of indigenous a... more The purpose of research is to model and correlate the laboratory rutting behavior of indigenous asphalt mixtures, prior to placing in the field. Extensive laboratory testing was carried out on thirty representative wearing course mixtures using two types of rutting performance tests i.e. CWTT (Cooper Wheel Tracking Tests), and APA (Asphalt Pavement Analyzer) tests. The mixture ranking is consistent for both laboratory performance tests at the tested temperature conditions of 40and 50 o C. Laboratory rutting prediction models have been developed by non-linear regression analysis technique. Significant independent variables involved in the model are temperature, number of passes in case of CWTT or number of cycles in case of APA tests, bitumen penetration value, and Flakiness index of coarse aggregates fraction. A strong relationship has been observed between measured and predicted values of rut depth in terms of R 2 value of 0.92 and 0.95 for CWTT and APA tests, respectively. A reasonable empirical quadratic function correlation (R 2 = 0.69) has been developed between rut depth of CWTT and rut depth in APA test.
International Journal of Pavement Engineering, 2020
The permanent deformation of asphalt pavement under similar traffic conditions depends on a numbe... more The permanent deformation of asphalt pavement under similar traffic conditions depends on a number of factors. The factors considered in this study are bitumen source, aggregate source, aggregate g...
Sub grade strength, bitumen content of different structural layers and riding quality of wearing ... more Sub grade strength, bitumen content of different structural layers and riding quality of wearing surface are the most important factors that affect the overall performance of pavement so it is necessary to evaluate the structural behavior and surface characteristics of pavement. The study reveals that runway of new Benazir Bhutto International Airport Islamabad will behave under the heavy loading of aircrafts as per design requirements. This paper documents the Sub grade CBR tests, field density test, different layer's soil classification, profilograph tests and skid resistance tests were performed to find out structural performance of main runway, secondary runway and taxiway and then compared with internationally design standards. From this research, it was concluded that new BBIAP is properly designed according to specifications. IRI values of main, secondary and taxiway are 1.54, 1.99 and 2.96 respectively which are well within internationally accepted values. Optimum asphalt content of bitumen wearing and bitumen base courses are 5.10% and 4.50% respectively when tested on different samples by extraction tests. Loss of stability in Bitumen wearing course and Bitumen Base course are 18% and 9% respectively. It was also concluded that the best Soil used in sub grade of any pavement is A-2-4 with 95% compaction achieved. Because A-2-4 soil can bear maximum load with respect to other groups soil, it is considered to be very effective while preparing sub grade in any runway pavement. From this research, it was also concluded that the factor of percentage of bitumen is dominating factor in the behavior of resilient modulus at a certain limit , as we increase the percentage of bitumen resilient modulus increases and vice versa. After a certain limit resilient modulus decreases by increasing bitumen content.
Highway agencies have been using polymers in asphalt binders to reduce rutting-associated distres... more Highway agencies have been using polymers in asphalt binders to reduce rutting-associated distresses in asphalt pavements. Rheological parameters like complex shear modulus (G*) and phase angle (δ) in the form of G*/Sinδ were used to predict rut resistance of asphalt binders, which have been replaced by a new parameter called non-recoverable creep compliance. The present study investigates the creep compliance of straight run (neat) and polymer-modified asphalt binders, at their high performance grade temperature (58, 64, 70, and 76 °C), using a multi-stress creep recovery test. The test data are used to assess the temperature and stress sensitivity of asphalt binders at different percentages of polymer. Asphalt mixtures, prepared using four asphalt binders, are tested in a wheel tracker to arrive at a relationship between creep compliance and rut resistance of asphalt mixtures. This study has revealed that creep compliance depicts the temperature and stress sensitivity of asphalt binders and asphalt binders’ polymer modification. Based on the stress sensitivity and creep compliance data, the suitability of asphalt binders for different traffic loadings is suggested. The present study proposes a reasonable relationship between creep compliance at 3.2 kPa and rut depth of asphalt mixtures, obtained from a wheel tracker test. This laboratory study may be extended in the future for field validation and development of asphalt mixtures performance-related specifications.
Journal of the Chinese Institute of Engineers, 2014
ABSTRACT The present study evaluates the effect of aggregate gradation with different nominal max... more ABSTRACT The present study evaluates the effect of aggregate gradation with different nominal maximum aggregate sizes on the stiffness, rutting, and fatigue performance of stone mastic asphalt (SMA). These performance parameters are important in mechanistic-empirical pavement design. Four SMA mixes with 4.75, 9.5, 12, and 19 mm nominal maximum size of aggregate in aggregate gradation and a PG 58-22 asphalt binder were designed. Dynamic modulus, wheel tracker, and four-point beam fatigue tests were conducted at different temperatures. A regression model has been utilized using wheel tracker test data, which reveals that rut resistance of SMA increases with an increase of aggregate size in aggregate gradation. Beam fatigue testing and asphalt binder drain down testing indicate that increasing aggregate size in an aggregate gradation decreases fatigue life and increases binder drainage, respectively. This study also reports some relationships between dynamic modulus, wheel tracker rut depth and fatigue life of SMA. A relationship between fatigue coefficients (K1 and K2) obtained from the fatigue curves has also been proposed. Analysis of results indicates that stiffer SMA has lower fatigue life and rut values. Rut resistance and mix stiffness increase with an increase in aggregate size in an aggregate gradation.
ABSTRACT Despite the widespread use of in-place recycling, limited information is available in th... more ABSTRACT Despite the widespread use of in-place recycling, limited information is available in the literature on in situ and laboratory properties of materials placed through in-place recycling. The main objectives of present study were to investigate the in situ recycled material characteristic that includes the potential of asphalt mixtures for permanent deformation, fatigue cracking, and low-temperature cracking, and the effect of a special technique of hot in-place recycling and rejuvenation on asphalt binder rheological properties. To accomplish these objectives, a two-phase experimental program was designed to determine the performance-related parameters of 100% in-place recycled mixtures using one of the in-place recycling techniques in which overlay is not needed. The experimental program included the measurement of mixtures’ mechanical properties and binder rheological properties. The present study revealed that the stiffness of the asphalt mixtures after recycling had increased compared to that before recycling. In general, specimens exhibited a low permanent deformation potential of 2–3 mm after 20,000 loading cycles by using the Hamburg wheel-track test. Stable crack propagation could not be obtained in the fracture tests at −12°C, which indicates the asphalt mixtures’ brittleness at that temperature. Asphalt binder and aggregates, extracted from the samples as collected at various stages of construction, were characterized to assess the effect of the recycling process on mixtures’ properties. Results obtained from the asphalt binder frequency sweep test indicate an increase in the modulus value, which was primarily caused by a heating process at surface layer. This increase in the modulus value of asphalt binder was efficiently compensated by an addition of a rejuvenator. Alternative additives or rejuvenators may also be considered to improve blending and compatibility between the old and new binder, and to reduce the mixture’s stiffness to avoid any possible premature deterioration. The selected rejuvenator should achieve several goals, including complete blending with existing binder and reducing the combined binder performance grade below the binder performance grade of existing mixes.
Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. T... more Mixes with finer aggregate gradation and soft asphalt binder showed better fatigue performance. The range of slope coefficient (K2), obtained from fatigue equation is from 2.03 to 4.25. A reasonable relationship exits between the slope and intercept coefficient of fatigue equation. Stone dust as filler improves the fatigue performance of asphalt mix.
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Papers by Imran Hafeez