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This study investigates the combined impact of Trinidad Lake Asphalt (TLA) and styrene–isoprene–styrene (SIS) on the performance of PG 64-22 asphalt binder. The study specifically examines how the addition of TLA and SIS affects the stiffness, viscoelastic properties, and ability to resist deformation of the asphalt binder, using the Superpave test method. The findings demonstrate that the addition of SIS improves the ability to withstand deformation, with the best results seen in the mixture containing 20% TLA and 5% SIS. This blend achieves a harmonious combination of stiffness, pliability, and ease of use. Increasing the SIS content to 10% and combining it with a 20% TLA greatly enhances resistance to rutting, but it also decreases workability. In addition, a mixture consisting of 10% TLA and 10% SIS provides excellent resistance to fatigue and possesses viscoelastic properties that are well suited for reducing oxidative aging and cracking. Although SIS typically enhances the performance of binders, an excessive quantity can result in unwanted rigidity, requiring meticulous optimization. The results highlight the importance of customizing TLA–SIS combinations according to specific environmental conditions in order to optimize advantages. Subsequent studies should investigate the prolonged impacts and alternative combinations of additives to further improve the performance of binders. [ABSTRACT FROM AUTHOR]

This study investigates the combined impact of Trinidad Lake Asphalt (TLA) and styrene–isoprene–styrene (SIS) on the performance of PG 64-22 asphalt binder. The study specifically examines how the addition of TLA and SIS affects the stiffness, viscoelastic properties, and ability to resist deformation of the asphalt binder, using the Superpave test method. The findings demonstrate that the addition of SIS improves the ability to withstand deformation, with the best results seen in the mixture containing 20% TLA and 5% SIS. This blend achieves a harmonious combination of stiffness, pliability, and ease of use. Increasing the SIS content to 10% and combining it with a 20% TLA greatly enhances resistance to rutting, but it also decreases workability. In addition, a mixture consisting of 10% TLA and 10% SIS provides excellent resistance to fatigue and possesses viscoelastic properties that are well suited for reducing oxidative aging and cracking. Although SIS typically enhances the performance of binders, an excessive quantity can result in unwanted rigidity, requiring meticulous optimization. The results highlight the importance of customizing TLA–SIS combinations according to specific environmental conditions in order to optimize advantages. Subsequent studies should investigate the prolonged impacts and alternative combinations of additives to further improve the performance of binders.

Difficulties in meeting the minimum voids in mineral aggregates (VMA) requirement of Superpave have been a common adversity for researchers in the mix design phase. The rationale behind having minimum VMA criteria was to guarantee durability of asphalt mixtures. However, multiple studies have demonstrated weak relationship between VMA and durability. In this study, the validity of the VMA criteria of the Superpave mix design was investigated using the film thickness perspective. Seven gradations with a nominal maximum aggregate size NMAS of 12.5 mm of different types (coarse, dense, gap, and fine) were considered. A poor relationship was found between the VMA and the film thickness FT (durability indicator) enforced with a coefficient of determination R 2 = 0.0098 for the regression between FT and VMA. Moreover, a poor relationship was found between the effective binder content (Pbe) and VMA supported with a coefficient of determination R 2 =0.01 for the regression between the effective binder content (Pbe) and VMA. Both regression results indicate that the current VMA criteria is not strongly referring to the mixture durability. The weakness of these relationships was also verified on seven 19 mm gradations. An approach to calculate the minimum VMA based on the mixture components is suggested. Based on the proposed approach and volumetric results, it is shown that the minimum VMA requirement of Superpave is disqualifying acceptable mixtures, especially coarse graded, that have VMA values higher than the minimum required to ensure the durability. [ABSTRACT FROM AUTHOR]

Research outputs undertaken in temperate climates require adaptation and customisation before they can be applied to tropical conditions. This often requires the use of research trial sections with a revised technology. The construction and performance monitoring of trial sections takes time, often spanning several years. However, the demands of road agencies can mean that there is insufficient time to undertake the necessary trials. In such cases, large scale projects are often undertaken with inflated factors of safety. This frequently results in higher execution costs and no guarantees of adequate performance. This paper examines the circumstances under which the application of Superpave asphalt mix design technology in a major road project in Uganda (a tropical country) resulted in premature pavement failure, which started within two years of completion. The Superpave asphalt mix design method was developed under the Strategic Highways Research Programme in the United States of America (a temperature region), funded by AASHTO. Defects were first observed on the project road (Mbarara to Katuna) during the works execution and within the one-year defects liability period. To assess the performance of the sections, detailed visual condition surveys were undertaken; asphalt cores were used to test for strength, water sensitivity, and volumetric characteristics in the laboratory. Deflection measurements and analysis were also carried out. The results showed that the pavement failure was confined to the asphalt surfacing. The Superpave asphalt mix did not perform as expected, due to the difference in climatic, traffic, and construction characteristics Adjustments should have been made, based on findings from trial sections, to make the surfacing suitable for tropical conditions. Ultimately, tropical countries should engage in coordinated and targeted applied research that places emphasis on the adaptation of technologies. [ABSTRACT FROM AUTHOR]

The new class of reactive polymers is designed to modify asphalt through chemical reactions with asphalt components. The complexity of such systems and the long experience with thermoplastic elastomers as well as with some other "classical" modifiers, and to a degree that our present testing methods and even specifications revolve around these materials, might obscure the fact that we are dealing with rather different modification systems and possibly with new emerging asphalt paving technologies. Our present work attempted to compare two different reactive polymer systems with the "classical" system which uses thermoplastic elastomer. The impact of reactive polymer systems on asphalt was studied through material properties manifested by specification tests and through the development of thermo-rheological properties in linear and non-linear viscoelastic regions. As expected, the behavior of reactive polymeric systems with different chemistries also differed among themselves. The available results showed that the reactive groups of polymers react with polar components of asphalt leading to higher stiffness at elevated pavement temperatures and differing impact on low temperature properties. The data point to a significantly improved resistance to plastic deformation of pavement in the case of reactive polymers, despite the fact that elastic recovery-based specification tests failed to identify this improvement. [ABSTRACT FROM AUTHOR]

This paper introduces the maximum and minimum pavement temperatures of Estonian asphalt pavements in accordance with calculation models developed for North America and Norway. Historical meteorological data from 1992 to 2021 obtained from 25 different weather stations in Estonia were used as an input for the respective models. Comparison between the calculation models demonstrated high variability of the pavement design temperatures, thus significantly impacting the bitumen grade selection. Based on the road weather stations data, the Norwegian and Canadian models provide the most accurate pavement temperature estimations for Estonian conditions. Calculated upper and lower-bound pavement design temperatures varied between +52 °C to +58 °C and −22 °C to −34 °C, respectively. All models showed milder pavement temperatures and lower seasonal temperature amplitudes for coastal and offshore areas. The results also indicated the importance of validating model suitability as well as correlation with actual pavement temperatures in the Baltic region.

This research study aimed to assess the influence of different particle sizes of crumb rubber modifier on phase separation when mixed with virgin asphalt binder (PG 64-22). Both Superpave and multiple stress creep recovery (MSCR) tests were conducted to determine the optimal particle size. Three sizes of crumb-rubber particles (≤0.5 mm, ≤1 mm, and 1–2 mm) were individually incorporated into the binder at a weight proportion of 10%. The findings revealed that an increase in particle size resulted in higher viscosity, which reduced workability. However, the use of particles with a size of ≤0.5 mm effectively decreased viscosity. Furthermore, larger particle sizes enhanced resistance to rutting and improved the lifespan of the pavement. Multiple shear creep recovery (MSCR) tests confirmed that larger crumb-rubber particles exhibited a higher load-bearing capacity. Additionally, phase separation studies demonstrated that larger particle sizes were associated with increased phase separation. Notably, particles with a size of ≤0.5 mm performed exceptionally well in reducing phase separation across all combinations. In conclusion, crumb-rubber particles with a size of ≤0.5 mm were identified as the most effective in minimizing phase separation when blended with virgin asphalt binder. These findings provide solid scientific evidence related to the effects of crumb-rubber particles on the storage stability of rubberized asphalt binder and have significant implications for future research in this field. [ABSTRACT FROM AUTHOR]

In this study, conventional bitumen tests were performed on bituminous binder modified with Cocamide Diethanolamide chemical at different ratios. According to results of tests, the most suitable additive ratio has been determined as 5%. However, it was concluded that indirect tensile strength and resistance to moisture of samples prepared with bituminous binder modified with 5% Cocamide Diethanolamide has been adversely affected. It was desired to investigate that whether these properties could be strengthened by yarn waste fibers. Firstly, the effect of 0.1%, 0.2% and 0.3% yarn waste fibers on samples prepared with reference bituminous binder was investigated. Obtained results showed that both indirect tensile strength and resistance to moisture of samples containing 0.1% yarn waste fiber increased. Therefore, 0.1%, 0.2% and 0.3% yarn waste fibers were added to the aggregate mixture and mixing of them with bituminous binder modified with 5% Cocamide Diethanolamide was provided. According to obtained results, different ratios of yarn waste fibers added to aggregate mixture did not have a positive effect on moisture sensitivity. Tensile strength ratio values of samples containing bituminous binder modified with 5% Cocamide Diethanolamide and yarn waste fibers added to the aggregate mixture did not provide specification limit

Asphalt binder is a temperature-sensitive material with a performance that is greatly affected by changing climates. Improper selection of asphalt will cause a lot of damage and affect the durability of the road. The establishment of asphalt pavement performance zoning in Xinjiang, a vast area with great temperature differences, will provide a reference for the selection of asphalt suitability, the refinement of pavement design, and the sustainable development of road engineering. In this study, 11 years of temperature data in the Xinjiang region have been collected and analyzed, and 98% reliability of pavement design temperature has been used to draw a performance grading map of asphalt pavement in the Xinjiang region based on the ArcGIS platform. Finally, the Xinjiang region is divided into nine performance zones. At the same time, the performance grades (PG) of five kinds of asphalt binders in Karamay are explored. The result shows that there is little difference in continuous PG span between different matrix asphalt binders; the lower the penetration grade, the better the high-temperature performance, and the worse the low-temperature performance. After adding the SBS modifier, the continuous PG span can be about 20 °C higher than the matrix asphalt. The indoor test of asphalt mixture also shows that SBS-modified asphalt has better durability. All these provide the basis for a reasonable selection of asphalt binders in different areas of Xinjiang. [ABSTRACT FROM AUTHOR]

This research studied the sustainable utilization of waste ceramic in asphalt mixtures by substituting fine aggregate with treated and untreated waste ceramic produced from construction and demolition activities. To improve its adhesion to the asphalt binder and lower the moisture susceptibility of Superpave asphalt mixes, the waste ceramic was treated with a silane anti-stripping agent. The Marshall quotient (MQ), Marshall stability (MS), indirect tensile strength (ITS), retained Marshall stability (RMS), and tensile strength ratio (TSR) were used to assess the mechanical performance and moisture susceptibility of all mixes. The changes in the chemical composition, synergy, physical state, and microstructure of the studied composites were also investigated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results revealed that substituting fine aggregate with 50% silane-treated waste ceramics reduced permanent deformation by 46%. Moreover, integrating silane-treated ceramics reduced asphalt mixture moisture susceptibility, with an RMS value of 87.7% obtained for asphalt containing 75% treated ceramic particles. The application of a silane anti-stripping agent resulted in high adhesion between the ceramic particles and bitumen as well as the production of fewer air voids in the mixes due to the formation of strong CH aromatic linkages, as well as Si-O and Si-O-Si bonds. The possibility of employing waste ceramics in asphalt mixes as a sustainable alternative to virgin aggregates while decreasing environmental impacts and improving resource efficiency is highlighted in this paper. [ABSTRACT FROM AUTHOR]

This paper introduces the maximum and minimum pavement temperatures of Estonian asphalt pavements in accordance with calculation models developed for North America and Norway. Historical meteorological data from 1992 to 2021 obtained from 25 different weather stations in Estonia were used as an input for the respective models. Comparison between the calculation models demonstrated high variability of the pavement design temperatures, thus significantly impacting the bitumen grade selection. Based on the road weather stations data, the Norwegian and Canadian models provide the most accurate pavement temperature estimations for Estonian conditions. Calculated upper and lower-bound pavement design temperatures varied between +52 °C to +58 °C and −22 °C to −34 °C, respectively. All models showed milder pavement temperatures and lower seasonal temperature amplitudes for coastal and offshore areas. The results also indicated the importance of validating model suitability as well as correlation with actual pavement temperatures in the Baltic region. [ABSTRACT FROM AUTHOR]

O Reclaimed asphalt pavement (RAP) tem se revelado de uso potencial na composição de novas camadas granulares e até mesmo de revestimento de pavimentos. Em países como os europeus, EUA, Japão, as misturas asfálticas utilizam porcentagens da ordem de 10 a 30%, incentivando a instauração de tal metodologia também no Brasil. Nacionalmente, existem obras com tal implementação, mas no estado Goiás não há incentivos para o uso do RAP. Portanto, o objetivo deste artigo é estudar o comportamento mecânico de misturas asfálticas com elevada incorporação de RAP e compara-las a misturas recicladas e convencionais. Para tanto, misturas compostas por 33%, 45% e 100% de RAP, agregados e ligantes novos e, ainda, agente rejuvenescedor foram produzidas em laboratório. As misturas foram projetadas por meio de seleção granulométrica Bailey e dosagem SuperPave, e submetidas a ensaios mecânicos para verificação de desempenho. Quando as misturas compostas por RAP foram comparadas às misturas convencionais, verificou-se comportamento mecânico similar ou superior. Ao propor o uso do método Bailey, pôde-se verificar a influência frente à rigidez, por meio da relação entre o agregado graúdo e os valores de módulo de resiliência. Já os valores de flow number diminuíram com o aumento do teor de ligante. Em geral, os resultados obtidos embasam a viabilidade técnica do uso de RAP, bem como a maior eficiência dos métodos de seleção e avaliação granulométrica. A importância da continuidade desses estudos também é enfatizada, objetivando a padronização, para a obtenção de estruturas asfálticas mais sustentáveis e duráveis.

The main objective of this study is to compare the differences between different gradation types of mixtures (stone matrix asphalt (SMA), large stone asphalt (LSA), stone asphalt concrete (SAC), and superior performing asphalt pavements (Superpave)) and conventional dense-graded mixtures (asphalt concrete (AC)) in terms of resistance to rutting, moisture damage, low-temperature cracking, and water permeability. The paper reports a study of the effect of different asphalt binders on the performance of asphalt mixtures. The experimental results demonstrated that the gradation types had a significant effect on the engineering performance of asphalt mixtures. SMA20, SAC20, and LSA30 exhibited lower rutting potential than AC20. In addition, SAC20 had a larger stripping ratio, while AC13 had a smaller stripping ratio. The stone matrix asphalt displayed the largest failure strain, while the SAC had the smallest, and Superpave ranged between SMA and SAC. SAC20 had the maximum permeability coefficient, followed by SMA20 and AC20, and Superpave20 had the smallest. The nominal maximum aggregate sizes significantly affected the resistance to permanent deformation, resistance to low-temperature cracking, and moisture sensitivity of the asphalt mixtures. Styrene–butadiene–styrene (SBS)-modified asphalt was found to significantly improve the performance of asphalt mixtures compared with ordinary asphalt.

Construction techniques and mix design methods are subjected to continuous development along with new inventions, technologies, and related implementation strategies. Due to recent materials introduced into asphalt mixtures such as modified asphalt binders, high percentages of Reclaimed Asphalt Pavement (RAP), warm mix technologies, recycling agents, and others, the asphalt industry is rapidly moving toward the Balanced Mix Design (BMD) method. Current asphalt mixture design methods are structured around meeting a range of volumetric requirements and sometimes other properties such as stability and/or moisture sensitivity. Although this allows for volumetric parameters to be monitored and controlled during production, it does not give much engineering insight as to how the mixture will perform under field conditions. The objective of this research was to assist the local agencies in Nevada with the transition from the Marshall method to the BMD, the latest methodology for designing asphalt mixtures, using the Superpave gyratory compactor and performance tests. Based on experimental data, the research team aimed to create an approach for an optimised, and high-performing mix designs with the use of 15% RAP along with an implementation plan that could be adopted by local agencies and serve as an example for other agencies. [ABSTRACT FROM AUTHOR]

MassDOT is evaluating the potential of increasing the RAP content in their asphalt surface layers from 15% RAP to 20–25% RAP while keeping the virgin binder PG fixed at PG64-28. However, each RAP can have different properties such as binder PG and binder content and can include highly aged binders. Thus, using some RAPs without changing the virgin binder PG could lead to blended binders with unacceptable low-temperature PGs even at low RAP contents. In this study, RAP binders and virgin binders were sampled from around Massachusetts. The low-temperature continuous PGs of both binders were measured. An AASHTO blending equation was used to determine the low-temperature continuous PGs of blended binders based on using 15% and 25% RAP binder contents. An LTPPbind equation was then used to calculate the standard normal distribution Z, which provides the reliability that a blended binder will meet the low temperature PG required at a specific geographic location. The results showed the high impact of RAP source, RAP binder content, virgin binder source, and geographic location on low-temperature PG reliability, and that keeping the virgin binder PG fixed at PG64-28 may not always provide binders suitable for western and northern Massachusetts. [ABSTRACT FROM AUTHOR]

In this study, conventional bitumen tests were performed on bituminous binder modified with Cocamide Diethanolamide chemical at different ratios. According to results of tests, the most suitable additive ratio has been determined as 5%. However, it was concluded that indirect tensile strength and resistance to moisture of samples prepared with bituminous binder modified with 5% Cocamide Diethanolamide has been adversely affected. It was desired to investigate that whether these properties could be strengthened by yarn waste fibers. Firstly, the effect of 0.1%, 0.2% and 0.3% yarn waste fibers on samples prepared with reference bituminous binder was investigated. Obtained results showed that both indirect tensile strength and resistance to moisture of samples containing 0.1% yarn waste fiber increased. Therefore, 0.1%, 0.2% and 0.3% yarn waste fibers were added to the aggregate mixture and mixing of them with bituminous binder modified with 5% Cocamide Diethanolamide was provided. According to obtained results, different ratios of yarn waste fibers added to aggregate mixture did not have a positive effect on moisture sensitivity. Tensile strength ratio values of samples containing bituminous binder modified with 5% Cocamide Diethanolamide and yarn waste fibers added to the aggregate mixture did not provide specification limit. [ABSTRACT FROM AUTHOR]

This work aimed to optimize the production of hot mix asphalt (HMA) from the use of asphalt-rubber. For that, the mechanical performance of asphalt mixtures produced with different binders was evaluated: commercial asphalt-rubber (AR08), asphalt crumb rubber 10% (AR10) and 15% (AR15), and conventional asphalt (PEN 50-70). For the composition of these mixtures, the optimum asphalt contents were defined by the Marshall design. To carry out the mechanical tests, specimens molded with Marshall and Superpave compactors were tested. From the results obtained, it was verified that AR08 and AR10 asphaltic mixtures, compacted with Superpave, carried out the best mechanical performance. However, the AR08 binder is already available on the market, which facilitates its usage in paving works

The Superior Performing Asphalt Pavements (Superpave) system – comprising asphalt binder grading, mixture design and mixture performance evaluation – has been in existence for nearly 30 years and has been implemented or evaluated for possible adoption in several countries to help address fatigue cracking, rutting and thermal cracking. These asphalt pavement distresses minimize pavement integrity to cause significant increase in maintenance cost, safety risks and roughness. Premature fatigue cracking and rutting failures are common in Ghana. Currently, only the mixture design component of the Superpave system is an option in the country's standard construction specification; asphalt binder selection is based on viscosity grading. Recently, very few projects have utilized Superpave-graded binders, and some of the binder grade selections were problematic. The use of Superpave-graded binders on high-volume roads is anticipated to become a common practice in the foreseeable future. However, there is no road agency guidance document on Superpave binder grade selection in Ghana currently, and this study sought to fill the gap. Such a guidance document will facilitate binder grade selection and streamline binder grade selection practices. This study utilized 42 years (1979–2020) of air temperature data collected from 24 weather stations across the country and measured asphalt pavement temperature to evaluate four existing Superpave binder grade prediction models. The model derived from the Long-Term Pavement Performance program better represented Ghana's climatic conditions and suggested the country may be partitioned into two Superpave binder grade selection zones: the Northern Savannah zone and the Transition/Forest/Coastal zone. At 98% reliability level, a binder grade of PG 70–10 was determined for the northern sector and PG 64–10 for the rest of the country. These are base binder grades (based on weather only) which must be adjusted for traffic conditions at the project site. Research should focus on local model formulation for refined Superpave binder grade selection and, during construction, selected binder grades must be verified through laboratory testing. Proper binder grade selection must be supplemented with effective pavement design, construction, axle load control and maintenance for good pavement performance and longevity.

The extreme arid climatic conditions and poor asphalt mix design characteristics have further accelerated the rate of deterioration of in-service asphalt pavements in Kuwait. Pavement distresses, such as raveling, rutting, and fatigue cracks, worsen in severe climatic and loading conditions, such as high temperatures, elevated humidity levels, and high traffic loads on the pavement surfaces. In this study, a life performance evaluation using mechanistic–empirical analysis of a new modified Superpave mix design was undertaken. The performance life of the modified Superpave asphalt mixture was evaluated, and the results showed that the new modifications to the mix improved the rutting and fatigue cracking resistances of the asphalt mixture for the unconditioned state. However, fatigue cracking resistance under the moisture-conditioned state still needs further improvement for the newly modified Superpave asphalt mixture.

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In this study, ethylene vinyl acetate (EVA) polymer and rubber powder were used as 85/100 bitumen modifiers. First, classical bitumen tests including penetration grade and softening point were performed on the samples and improvement of bitumen base properties was observed. Then, in order to evaluate the performance of modified bitumen at high temperature and compare it with the behavior of base bitumen, the Superpave protocol was followed. In this way, dynamic shear rheometer (DSR) test was performed and G*/sinδ index was examined on bitumen samples before and after aging. In addition, the bending beam rheometer (BBR) test was performed to evaluate the low temperature behavior of the modified bitumen according to the SHRP standard based on the creep stiffness and creep rate indices. The results showed that the combination of used additives improves the performance properties of bitumen at high temperature and also at low temperature compared to base bitumen. Based on the BBR test, 3% EVA polymer and 4% rubber powder, with a 12% reduction in creep stiffness in this composition, were selected the optimal values for the mixture.

The roadway industry in Pakistan is flourishing with one belt one road project. In near future, the roads of the country will help to accommodate the trade of billions of dollars from south Asia to the entire world. This project have increased the importance of flexible pavements in view of its widespread use in the local roadway industry due to low construction and maintenance costs. In Pakistan, local highway authorities rely on Marshal mix design method to design wearing course asphalt mixes. This method is empirical in nature and fails in accurately determining the behavior of flexible pavements due to variable environmental and traffic load conditions, and material properties. Considering these limitations, this study is an initial attempt in Pakistan to evaluate and compare asphalt mixes prepared based on both modern mix design method referred to as superior performing asphalt pavements (SUPERPAVE) and already adopted conventional mix design method using locally available material queries and considering local environmental and loading conditions. Using most common pavement conditions, comparative research was carried out to judge the performance of wearing course asphaltic mixtures prepared based on both Marshall and SUPERPAVE techniques. The matrix of the experimental plan involves one locally available aggregate source, two different aggregate gradations, and one locally available binder type. For mix evaluation, two sets of samples were prepared at optimum asphalt binder content and selected aggregate gradations for the two mix design methods under study. Performance of each mix type was then evaluated by mechanical properties including marshall stability, loss of marshall stability, indirect tensile strength, loss of indirect tensile strength, and modulus of resilience. [ABSTRACT FROM AUTHOR]

Asphalt binder is a viscoelastic material. Its physical and rheological properties are highly affected by temperature to which it will be exposed during its entire life. Choosing the right performance grade (PG) asphalt binder is a very important step in flexible pavement design and construction. The PG-asphalt binder depends on pavement temperature which is directly related to air temperature of the region in which the pavement will be constructed. This study focuses on forecasting flexible pavement temperatures by Fourier series formulae using MATLAB. General Fourier series formulae have been locally developed to study thermal changes during different periods of time and directly link them to the temperature of pavement. By using the MATLAB program and air temperature data, the developed Fourier series formulae were able to obtain high-accuracy future predictions of air temperatures. The Strategic Highway Research Program (SHRP) models were then used to predict pavement temperatures using air temperatures, thereby helping engineers determine the best PG-asphalt binder for the studied period of time as well as for the future. The study results indicated that the best PG-asphalt binder for the studied region is 64-10 based on the daily model for one, two and five years, as it simulates fluctuations in the maximum and minimum temperatures on a daily basis. The same results were found by previous studies that were carried out in Amman city. [ABSTRACT FROM AUTHOR]

This study was designed to analyze the characteristics of two recycled fillers, hollow concrete block (HCB) powder and brick powder (BP), and to assess their respective impacts on the mechanical properties of hot-mix asphalt (HMA) when used as complete replacements for limestone (LS) filler. The recycled and LS fillers are obtained from construction and demolition wastes and naturally mined for commercial uses, respectively. Filler characteristics were examined using Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscopy. The respective effects of the fillers and the mechanical properties of the HMA mixtures were assessed using Marshall stability, indirect tensile strength, moisture damage by tensile strength ratio, indirect tensile cracking index, and permanent deformation tests. The results demonstrated that HCB powder significantly improved moisture, rutting, and crack resistance in HMA, which are factors critical to extending the life of asphalt concrete. In contrast, using BP resulted in mixed values and negative effects, particularly in terms of moisture resistance and rutting. [ABSTRACT FROM AUTHOR]

Bu çalışmada ekonomik ömürlerini tamamlayarak yıkılan binaların atıkları öğütülerek agrega haline getirilmiştir. Referans kireçtaşı numunesi ve bina atıklarından elde edilen agrega numunelerinin, fiziksel ve mekanik özellikleri belirlenerek şartname limitleri ile karşılaştırılmaları yapılmıştır. Bununla birlikte agrega haline getirilen atıklar Bitümlü Sıcak Karışım (BSK) numuneleri ile kalan kısmı kireçtaşı olmak üzere, sırasıyla %100, %75, %50 ve %25 oranlarında karıştırılmıştır. Her farklı karışım oranı için karışımın SuperpaveTM yöntemi ile hacimsel analizi yapılarak optimum bağlayıcı içeriği belirlenmiştir. Optimum bağlayıcı içeriği belirlenen numunelerin AASHTO T 283’e göre nem hassasiyetleri incelenmiştir. Ayrıca atık ilave edilmeyen referans kireçtaşı numuneleri için de deneyler yapılmış ve sonuçlar bina atıkları ile karşılaştırılmıştır. Test sonuçlarının Karayolu Teknik Şartnamesi limitleri ile kıyası yapıldığında, atık numunelerin su emme oranları ve Los Angeles aşınma deney sonuçlarının şartname limitlerini aştığı gözlemlenmiş olup, bina atıklarının bitümlü temellerde ancak %25 oranında kullanılabileceği belirlenmiştir.

Purpose: To evaluate the superpave design performance using Epolene (EE-2) as modifier, since SUPERPAVE design is a modified and sophisticated aspect as compared to previous mix design for asphalt mixtures. This is primarily due to the fact that superpave design mix also takes into consideration properties of materials beside asphalt. Design/methodology/approach: This study was conducted using Epolene (EE-2) as modifier in order to evaluate the performance of SUPERPAVE suitability for construction of roads in Alfaraa campus (King Khalid University) Abha, in Asir Province of Saudi Arabia. Glow number test, dynamic modulus test and indirect tensile strength test were conducted to evaluate the performance of EE-2 modifier against the control mixture. Findings: The mixture modified with EE-2 gave better performance in terms of temperature-based performance and resistance to moisture damage. Also, larger values of E*/sinφ were obtained for EE-2 modified mixture at various loading frequencies and temperature in comparison to control mixture. Research limitations/implications: The Epolene modifier successfully enhances and improves the SUPERPAVE mixture performance. Further studies are required to evaluate the performance of EE-2 modifier at much lower temperature ranges. Practical implications: The results of the study allow us to recommend the investigated asphalt mixture for applied for the construction of roads in the Alfaraa (new campus of King Khalid University), Abha, Asir province, Saudi Arabia. Originality/value: A modified asphalt mixture has been proposed that has better performance at higher and lower temperatures. The developed asphalt mixture is more resistant to moisture damage than the compared to control mixture. [ABSTRACT FROM AUTHOR]

Although Caltrans has utilized the Hveem mix design process for hot mix asphalt for decades, it is currently implementing the Superpave mix design procedure, and is interested in including performance-related tests for mix design and quality assurance. Performance-related tests are also used for Caltrans mechanistic-empirical (ME) pavement design. This report includes descriptions of current performance-related tests and alternatives, including tests using the Asphalt Mixture Performance Tester (AMPT) device for permanent deformation, stiffness and fatigue, and other alternatives to the flexural beam and repeated shear tests currently used for ME characterization by Caltrans. The tests are compared for mixture design and quality assurance, and for characterization for ME design in terms of the usefulness of the results, and the difficulty and time required to obtain results. The report also presents an evaluation of the effects on mix properties for Hveem versus Superpave mix designs and the results of ME simulation of the effects on pavement performance for rutting and cracking. The results indicate that there is potential to use the unconfined Repeated Load Triaxial (RLT) test as a substitute for the repeated shear at constant height (RSCH) test for mix design and quality assurance, and to use the confined or unconfined RLT for ME characterization. However, the preliminary results regarding use of shift factors to convert results from RLT to RSCH to enable application to previously calibrated models needs more comprehensive evaluation. The results indicate that the direct tension (DT) test offers no advantages over flexural beam testing for ME fatigue characterization, and that the fracture energy index and fracture toughness parameters from the Semicircular Beam (SCB) Test may be useful for quality assurance and mix design. Results indicated that the Indirect Tension Test (IDT) did not correlate with flexural fatigue life. Results for the Hamburg Wheel-Track Testing (HWTT) indicated poor correlation with the RSCH for rutting potential.

Metal hydroxide has been widely used as flame retardant to reduce the hazards of tunnel fire, however, few researches investigate its effect on the rheological properties of asphalt binder systemically. This study explores and compares the effect and mechanisms of magnesium hydroxide (MH), aluminium hydroxide (ATH), hydrated lime (HL), and layer double hydroxides (LDHs) on the rutting resistance, anti-aging resistance, as well as the thermal cracking resistance of asphalt binder. Rotational viscosity (RV) test, dynamic shear rheometer (DSR) test, and bending beam rheometer (BBR) test are involved in the project. Test results indicate: (1) the addition of metal hydroxide generally improves the rutting resistance of asphalt binder during high temperatures due to the typical filler effect, while weakens the resistance to thermal cracking of binder at low temperatures because of the stress concentration; (2) HL and LDHs enhance the anti-aging resistance of asphalt binder; (3) LDHs modified binder, which is proved with better rheological properties, including great rutting resistance, anti-aging resistance and passable resistance to thermal cracking, is recommended for further use. However, the high procurement price is still a big obstacle for its wider application. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.21572

Back in 1993, Strategic Highway Research Program introduced new mix design method known as SUPERPAVE that is an acronym of Superior Performing Asphalt Pavement. Superpave caters filed performance of bituminous mixes and Superpave gradation chart includes 0.45 power line, restricted zone and control points. In Superpave, the gradation that compliance with the restricted zone was considered less rut resistant as compared to gradation passing outside the restricted zone. This study targets three types of gradations that passed above, below and through the restricted zone. The results show that the gradation passing through the restricted zone not only satisfy Superpave volumetric requirements but also performs better against rutting as compared to gradation passing outside the restricted zone. Resilient modulus (MR) measured through indirect tensile strength setup that defines the elastic properties of bituminous mix under repeated load test. Laboratory study was conducted to find factors that affect the gradation. Two-way factorial design was carried out by using Minitab-15 statistical software and the results reflected that the individual factor i.e. loads duration and temperature as well as interaction of factors has significant effect on the performance of HMA.

The presence of water in the pavement structure causes early deterioration and leads to less pavement durability as a result of loss of bond between aggregate and binder and may causes loss of strength and stability in mixture, The main goal of this study was to investigate the effect of various polymer additives on permeability of asphalt concrete mixture. The surface wearing coarse type IIIA was chosen in this study. Three types of polymer additives were used in this study; (7% Latex Emulsion (LE), 7% Poly Vinyl Acetate with 4% Styrene Butadiene Styrene (PVA + SBS) and 8% Ethylene Diamine (ED)). The results appeared that the permeability average of all mixtures were (27.745, 17.18, 7.773 and 11.409 * 10 -5 cm/s) for (control blend, LE, PVA+SBS and ED) and the percent of decreasing in permeability were (48.52%, 74.547% and 58.312%) for (LE, (PVA + SBS) and ED) respectively.

In this study, the wastes of the buildings that were destroyed by completing their economic life were granulated into aggregate. Comparisons were made with specification limits by identifying physical and mechanical properties of raw limestone and aggregate obtained from demolition wastes. Afterwards, the granulated aggregate was mixed into Hot Mix Asphalt (HMA) at 100%, 75%, 50% and 25% by weight and the remaining part is used as limestone. For each mixing ratio, optimum binder content was determined by using Superpave volumetric mix design procedure. The moisture susceptibility of the samples, with optimum binder content was determined according to AASHTO T 283. Moreover, tests were also performed for the samples without adding waste and the results were compared with the demolition waste samples. When the test results are compared with the limits of the Highway Technical Specifications, it is observed that the water absorption rates of the waste samples and the Los Angeles abrasion test results exceed the specification limits, and it is determined that demolition wastes can be used only at a rate of 25% on asphalt base layers. [ABSTRACT FROM AUTHOR]

This paper evaluated alternative test methods to determine the crushing potential of aggregates and documented the influence of aggregate characteristics on the engineering properties of asphalt mixes. Six aggregates sampled from different sources were subjected to various aggregate tests, including the Los Angeles abrasion, micro-Deval, soundness magnesium, and acid insoluble tests. A Superpave mix with a 12.5-mm (1/2-in.) nominal maximum aggregate size gradation was produced with each aggregate source using the same PG 64-22 asphalt binder. The mixtures were produced to investigate the impact of aggregate properties on their volumetric properties as well as the tensile strength from the indirect tension tests and rutting potential from the Hamburg wheel tracking tests. Correlation analyses among the measured parameters identified the aggregate crushing value as a promising alternative test method to quantify the crushing potential of aggregates and to adjust the gradation accordingly to produce mixtures with optimized volumetric properties. [ABSTRACT FROM AUTHOR]

Growing urban populations and vehicle using increased the need for highperformance roads. For this reason, bitumen modification, which is one of the main components of commonly used bituminous hot mixtures (BSK), is made to improve performance properties and behavior of the bitumen. In this study; the use of pomace (olive oil waste), which emerged during the production of olive oil, in bitumen modification was investigated. Bitumen was modified by mixing pomace in 5 diffrent percentages by weight. To pomace modified bitumen, penetration test, softening point test, ductility test, elastic return test and specific gravity test were applied and performance values were compared with unmodified bitumen. Also obtained modified bitumen was used in mixtures and Superpave mix design was used for performans analysis of this mix. Indirect tensile strength test was applied to the obtained mixtures and the indirect tensile strength ratio (TSR) was calculated. It has been determined that the performance of the modified mixtures of pirina against moisture sensitivity is increased. In addition it was observed that the penetration values of the modified bitumen decreased and the softening point values increased. [ABSTRACT FROM AUTHOR]

In this study, a regression-based predictive model is developed from laboratory test data to determine rutting performance of Superpave asphalt-aggregate mixtures. A Hamburg Wheel Tracking Device was used to measure the rutting performances of the asphalt concrete samples. A total of eighteen (18) asphalt concrete mixtures were tested and used in this study. Laboratory rut data were fitted by Weibull distribution and the Weibull parameters were correlated to the mix properties, such as, aggregate gradation, binder property, effective specific gravity of the aggregate and mix volumetrics of the asphalt concrete samples. Statistical evaluation showed that a fairly accurate estimation of rut depth can be found by using the regression-based predictive model developed in this study. [ABSTRACT FROM AUTHOR]

This study aimed at using waste glass to improve shear properties of asphalt binders. Asphalt-glass mastics were prepared at four glass/asphalt (G/A) ratios: 0.05, 0.10, 0.20, and 0.30 by volume of asphalt. The Superpave dynamic shear rheometer (DSR) was used to measure the complex shear modulus value (|G*|) and phase angle (δ) for the control asphalt binder and the glass-asphalt mastics using frequency sweep tests conducted at nine loading frequencies: 10, 5.0, 3.0, 1.78, 1.0, 0.5, 0.3, 0.178, and 0.1 Hz and at a wide range of temperatures: 10, 20, 30, 40, 50, 60, and 70°C. Findings of the study showed that the waste glass filler improved |G*|/cos δ (elastic part), |G*|sin δ (fatigue parameter), and |G*|/sin δ (rutting parameter) of the asphalt binder by decreasing δ and increasing |G*| especially at lower temperatures and high frequencies. Consequently, this enhanced the rutting and fatigue resistance of asphalt binders and improved the Superpave high temperature performance grade. It was also found that the increase in the ratio of the mix to the control asphalt binder for any of these parameters and the decrease in the phase angle ratio of the mix to the control asphalt binder were statistically significant (using 0.05 significance level) at 0.30 G/A ratio. Hence, the glass can be mixed in practice with the asphalt binder to increase its stiffness and therefore the rutting resistance and to improve the asphalt binder's elastic part as a result of the decrease in the phase angle, which will improve the fatigue resistance. [ABSTRACT FROM AUTHOR]

Back in 1993, Strategic Highway Research Program introduced new mix design method known as SUPERPAVE that is an acronym of Superior Performing Asphalt Pavement. Superpave caters filed performance of bituminous mixes and Superpave gradation chart includes 0.45 power line, restricted zone and control points. In Superpave, the gradation that compliance with the restricted zone was considered less rut resistant as compared to gradation passing outside the restricted zone. This study targets three types of gradations that passed above, below and through the restricted zone. The results show that the gradation passing through the restricted zone not only satisfy Superpave volumetric requirements but also performs better against rutting as compared to gradation passing outside the restricted zone. Resilient modulus (MR) measured through indirect tensile strength setup that defines the elastic properties of bituminous mix under repeated load test. Laboratory study was conducted to find factors that affect the gradation. Two-way factorial design was carried out by using Minitab-15 statistical software and the results reflected that the individual factor i.e. loads duration and temperature as well as interaction of factors has significant effect on the performance of HMA. [ABSTRACT FROM AUTHOR]

A fatigue is the accumulation of the materials damage in asphalt concrete mixtures and growing of cracks, under increasing effect of repeated vehicular loading, aging and environment factors, in this research study the effect of temperature, asphalt content, mineral filler, applied Strain, and the polymer (SBS) as a modified asphalt to evaluate their effect on fatigue crack. To achieve the objective of this research, the Nottingham flexural fatigue test is considered and superpave mix design requirements are employed. Test specimens of 380 mm length by 60 mm width and 50 mm height were sawed from slabs of the prepared mixes by rolling wheel compaction. Using Controlled-strain procedure,the tests were conducted at temperatures of 10-20-30 ±1°C and at a frequency of loading of 5 Hz. The full factor design as well, three asphalt contents 4.72, 5.22 and 5.72%, mineral filler (Portland cement, limestone dust), applied strain (400-750µs), and (2-4%) percent of (SBS) polymer, Local material properties, stress level and environmental impacts are considered for this aspect. From the result, it is observed that 2% of SBS modified mixture given a best result due to increase the percent of fatigue life to (120%) as the average when compared with the control mixture, the fatigue life has a positive relationship with asphalt content and temperature when using control strain .The fatigue life of the mixture with limestone dust have result more than mixture with Portland cement,In the general, The fatigue lifeof mixture at 400µs has given result more than 750µs.