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Over the years, there have been many studies on the performance improvement of asphalt mixtures using different materials and additives, especially those of the recycled variety, because of the environmental benefits they bring to the design. This study investigated the properties of asphalt mixtures made with different amounts of calcium lignosulfonate (CLS), which is a waste product, and used the Balanced Mix Design (BMD) approach to determine the appropriate mix design for CLS-containing mixtures. In this process, the results of the dynamic creep test were used as a measure of rutting resistance, the results of the indirect tensile test were used as a measure of moisture susceptibility, and the results of the Illinois Flexibility Index Test (IFIT) and Indirect Tensile Cracking Test (IDEAL-CT) were used independently as a measure of cracking resistance. On the other hand, since previous studies have suggested that CLS has antiaging properties, the specimens were made and tested in two groups: those with long-term aging and without long-term aging. So the objective was to determine the amount of CLS that should ideally be used as a bitumen additive in aged and unaged asphalt mixtures. The results showed that using 15% or 20% CLS will always yield acceptable outcomes in terms of BMD criteria for both aged and unaged conditions. However, a CLS content of 10% may also be acceptable for both aged and unaged conditions if IDEAL-CT results are used as the measure of cracking resistance. [ABSTRACT FROM AUTHOR]

The use of coffee husk ash (CHA) as a mineral filler in hot mix asphalt was investigated in this study. Crushed stone dust (CSD) was used as the mineral filler in four distinct serial asphalt concrete samples (5.5%, 6.5%, 7.5%, and 8%) for this purpose. The samples' ideal bitumen content and Marshall stability (MS) value were calculated. The 6.5% filler asphalt series, which has offered the most stability, was picked, and CHA was substituted for it at rates of 25%, 50%, 75%, and 100%. The produced samples were then subjected to an MS test, and the results were evaluated. The effects of mineral filler on the susceptibility of asphalt concrete to moisture were also examined in the present study along with the preparation and evaluation of Marshall stability mixtures with various CHA and bitumen levels. The maintained stability test also evaluates a bituminous mix's capacity to be stripped. The findings indicated that for stability, flow, air voids, VFA, and bulk density, respectively, the optimum asphalt content (5.57%) and filling rate at 75% replacement of crushed stone dust with coffee husk ash had values of 16.820 kN, 4.983 mm, 4.435%, and 73.717%. CHA can be used as long as 75% of the CSD filler material complies with the minimum standards set by the Ethiopian Road Authority and global standards for the manufacturing of hot mix asphalt concrete. The retained stability (RS) test results showed that the retained stability values increased with an increase in bitumen content, indicating that the effect of moisture damage decreases with an increase in asphalt content because a high bitumen content will have a thicker content, which reduces the tendency for the water to percolate into the asphalt mix and cause moisture-related problems. [ABSTRACT FROM AUTHOR]

Cold recycling of asphalt mixes is becoming a usual pavement rehabilitation technique. The use of active fillers in conjunction with bituminous emulsion changes the properties of the mixes, mainly on the mastic characteristics. The use of active filler can make the mastic more brittle, but limited data are available on this aspect. In this study, emulsion-active filler mastics were prepared with two different mixing methods. Two different active fillers, ordinary Portland cement and fly ash, were used at four different contents with a single emulsion and an inert filler. Once cured, the mastics were tested with a dynamic shear rheometer (DSR) to get the viscoelastic properties at high temperature and with the double-edge-notched tension (DENT) test to look at the cracking potential at intermediate temperature. The results show that the order that the materials are incorporated during the mixing of the mastics does have a significant effect on the properties. Also, in terms of stiffness, the optimum amount of active filler is different for the cement than for the fly ash. For the cracking resistance, the results have shown that the addition of both active fillers does have an impact on the cracking resistance, but in the amount tested, no brittle fracture was observed. The results have shown that the type and quantity of active filler are important since it changes the fracture performance and the viscoelastic properties of bituminous mastic. [ABSTRACT FROM AUTHOR]

The difficulty in enhancing the low permeability of deep coal seams is the key problem restricting gas extraction. The technology of coal rock resonance and permeability enhancement excited by vibration wave is hailed as a new technology to enhance coal seam permeability. In particular, the effect of resonance and permeability enhancement is remarkable when the excitation frequency is exactly the same as the natural frequency of coal. In order to promote the application of the technology, the first step is to explore the variation characteristics of coal natural frequency and its influencing factors. In this study, two mathematical models of coal natural frequency were established, and the variations and influencing factors of coal natural frequency were discussed through an experiment on the natural frequency of coal. The results show that coal vibration has multiorder natural frequency which grows with the increase of the order. In addition, the natural frequency of coal is closely related to its elastic modulus, density, size, mass, stiffness, and other physical and mechanical parameters. The larger the coal size and mass are, the lower the natural frequency would be. The natural frequency parallel to the bedding plane is higher than that perpendicular to the bedding plane. For the saturated coal sample, moisture changes its density and reduces its elastic modulus. Consequently, its natural frequency is lower than that of the dried coal sample. The difference of organic matter and mineral content coal of different rank affects the physical and mechanical properties of coal, which leads to the difference in natural frequency of different-rank coals. The natural frequencies of different-rank coal show bituminous > anthracite > lignite. The natural frequencies of coal samples under different influencing factors are all tens of Hz. Thus, the vibration excitation of coal under the low-frequency condition is the focus of future research. The study can provide a theoretical basis for the technology of coal resonance and permeability enhancement excited by vibration wave. [ABSTRACT FROM AUTHOR]

Nanomaterials are emerging as one of the methods to improve the pavement industry. Due to that, this study explores the influence of nano TiO2 modified binder and mixture with 60/70 grade bitumen. The first stage discovers the physical properties of bitumen by undergoing penetration and softening point tests. Then, the nano TiO2 modified binder is evaluated in terms of its morphological and chemical properties. To verify the modified binder design, the mechanical performance of stone mastic asphalt (SMA) is assessed in terms of volumetric properties. From the results, 5% nano TiO2 modified binder shows significant improvement in terms of penetration and softening point. The results also show that the 3% nano TiO2 modified binder contributes the highest improvement in terms of its chemical properties and the morphological properties. Based on the morphological properties' evaluation, FTIR and XRD observed a sharp peak of nano TiO2 while the bitumen containing nano TiO2 is well distributed when SEM-EDX was applied. In addition, the volumetric properties of SMA also significantly improve with the addition of nano TiO2. It can be said that the addition of nano TiO2 is able to enhance the overall properties of bitumen. [ABSTRACT FROM AUTHOR]

Asphalt mixtures are the major constituent of road constructions. Those mixtures expose to high-temperature levels during the construction process and their life cycle. The bitumen aging occurred because of the harmful effects of elevated temperatures upon the asphalt mixtures, which leads to oxidation, evaporation, and physical hardening within the bitumen structure. The aging phenomenon can intensify the hardness and brittleness of bitumen, which negatively affects the performance of asphalt mixtures. Researchers have investigated different types of bitumen additives to diminish the negative effects of bitumen aging, among which biomass additives are more attractive for researchers because that additives are organic and mainly emanate from waste materials. The current study investigated the effect of calcium lignosulfonate (CLS) at four quantities (i.e., 5%, 10%, 15%, and 20% by the weight of base bitumen) as an antiaging bitumen additive on physical, workability, thermal susceptibility, rheological, and chemical properties of 60/70 penetration grade bitumen. The results revealed that although the addition of CLS into the bitumen enhanced the rigidity of bitumen against rutting failure at high-temperature conditions, the CLS-modified bitumen was more susceptible to fatigue failure than the virgin bitumen at low-temperature regions. The workability analysis showed that the CLS powder could improve the bitumen's consistency against permanent deformation at high-temperature levels. Although the bitumen's viscosity increased because of CLS modification, the CLS-modified bitumen provided acceptable workability based on the Superpave specifications. Outcomes from the rheological test revealed that the addition of CLS into the bitumen improved the rutting resistance of bituminous mixtures at high-temperature levels. The SARA analysis indicated that the hardening of CLS-modified samples emanated from the formation of asphaltenes within the bitumen because of CLS incorporation. Different types of aging indices, including PRP, SPI, VAI, and AIRF, which were calculated in this research, showed that the presence of CLS within the bitumen could retard the bitumen's aging process. [ABSTRACT FROM AUTHOR]

Industrial solid waste has been widely used as an alternative additive for bituminous material modification. This study aims to evaluate the basic properties and quantify the leaching potential of modified asphalt binders incorporating crumb rubber powder (CRP) from waste tires and tin slag (TS) for a local smelting company. Three percentages of CRP and TS, at 5, 10, and 15%, were considered. The conventional asphalt binder (PEN 60/70), CRP, and TS-based modified asphalt binders were analyzed for toxicity, softening point, penetration value, elastic recovery, torsional recovery (TR), and coatability index. The findings indicated that the addition of the waste materials led to no significant heavy metal content in the asphalt binder mix. Moreover, the basic and physical properties of the asphalt binders were also improved by 5, 10, and 15% of the waste, respectively. However, TS waste exhibited limited effects on all the parameters and had a 5% optimum dosage. The modified binders' results showed that the CRP modified asphalt binders had fewer heavy metals and responded more to elastic recovery and coatability. [ABSTRACT FROM AUTHOR]

In the present study, ethylene-vinyl acetate (EVA) and crumb rubber (CR) were used as bitumen modifiers. The experiment was designed by response surface methodology (RSM) at different levels of modifier additives based on the central composite design (CCD). Next, the Superpave protocol was followed to evaluate the modified bitumen performance at different temperatures compared with the unmodified bitumen. In this regard, to evaluate at high temperatures, a dynamic shear rheometer (DSR) test was performed, and G ∗ /sinδ index was examined on bitumen samples after aging. Besides, the bending beam rheometer (BBR) test was performed to evaluate the low-temperature behaviour of the modified bitumen according to the SHRP standard based on the creep stiffness and creep rate. The optimal combination of additives was evaluated using RSM and analysis of statistical values to improve the performance properties of bitumen at high and low temperatures. Moreover, based on the DSR and BBR test results, 5.6% of EVA and 3.9% of CR were selected as the optimal values for the modified bitumen behaviour at the high and low temperatures of the mixture. [ABSTRACT FROM AUTHOR]

Road maintenance operations involve the preservation of the optimal functionality of the pavement. Sometimes the rehabilitation of the pavement layout does not have long lasting effects due to a lack of compliance with the constraints imposed by the technical specifications for the design of materials. The purpose of this paper is to present an efficient BIM tool to help in road maintenance operations through the management of data arising from laboratory testing of road pavement bituminous materials required for the quality control of mixtures. The database associated to the BIM model is a collection of three years of data derived from laboratory investigation on bituminous mixtures' samples adopted for the maintenance of four main roads located in southern Italy. An algorithm that interacts with the three-dimensional road model has been implemented in order to give road administrations an easy-to-read alert signal for the road pavement structure of the road network that may present the most critical conditions due to poor mechanical and physical features. [ABSTRACT FROM AUTHOR]

Stone matrix asphalt (SMA) mixtures are one of the most resistant types of asphalt mixtures known to date that the bulk load is borne by the aggregate skeleton. In this research, the effect of crumb rubber powder (CRP), Vestenamer polymer, and warm additives, including Sasobit, ZycoTherm, and a porous and warm mix asphalt (PAWMA), was investigated on the moisture resistance of SMA mixtures. A segregation test was performed to determine the tendency of the polymer to separate from modified polymer bitumen under storage conditions. Also, a drain down sensitivity test was conducted to explore the bleeding phenomena and drain down of SMA mixtures. Finally, a boiling water test, as well as an indirect tensile strength (ITS) test, was applied to examine the sensitivity of mixtures to moisture. The segregation test results indicated that by the use of Vestenamer polymer, a conventional (low speed) mixer can be used instead of using a high-speed mixer, and this will be very important in the cost of rubber bitumen production. The drain down test results showed that cellulose fibers prevented the bitumen bleeding of SMA mixtures. Also, the results of the boiling water test indicated that CRP samples containing ZycoTherm had the highest moisture resistance compared to the other warm additives. Among various mixtures, 8% CRP-modified samples containing ZycoTherm resulted in the lowest amount of stripping in SMA mixtures, even more than the base sample. The ITS test results illustrated that the use of CRP, Vestenamer polymer, and warm additives had a significant effect on the ITS amounts of mixtures. Moreover, the samples containing ZycoTherm had the highest tensile strength ratio (TSR) compared to the other SMA samples. [ABSTRACT FROM AUTHOR]

This paper proposes using the master-curve band (MCB) to incorporate the unavoidable measurement errors and modeling uncertainty into the bitumen master-curve construction. In general, the rheological property of bitumen within the linear viscoelastic region is characterized by the master curve of modulus and/or phase angle, provided that the bitumen complies with the time-temperature superposition principle (TTSP). However, the master-curve construction is essentially a mathematical fitting process regardless of whether or not the original data is perfect enough to fit. For this reason, the MCB was introduced to consider the uncertainty information instead of a single master curve. Rheological data of four kinds of bitumen including unaged and aged bitumen were used to construct the MCBs. The results indicated that the generalized sigmoidal model showed the widest master-curve band, followed by Christensen-Anderson-Marasteanu (CAM) and CAM ( G g ) models. The width of MCB was a useful tool to identify the sensitivity of bitumen to rheological models. The sensitivity of bitumen to rheological models is associated with the number of active parameters in rheological models and model parameters' confidence intervals. The construction of an MCB was beneficial to select the rheological models. Accordingly, the CAM ( G g ) model is proved to be the best to analyze the aging effects. [ABSTRACT FROM AUTHOR]

Nanomaterials have a great potential for enhancing the performance of base asphalt binder. This study aims to promote the application of nano-TiO2/CaCO3 in bitumen and presents a study on rheological properties for TiO2/CaCO3 nanoparticle-bitumen. In this study, a series of laboratory experiments have been performed for bitumen with different nano-TiO2/CaCO3 dosages. Nano-TiO2/CaCO3-modified bitumen with optimum dosage was prepared for viscosity, dynamic shear rheometer (DSR), and beam bending rheometer (BBR) for assessing temperature sensitivity of bitumen, and the low-medium-high-temperature performances were analyzed for TiO2/CaCO3 nanoparticle-bitumen as well. Results show that bituminous mechanical properties were enhanced by TiO2/CaCO3, and based on the overall desirability analysis of various conventional tests, the reasonable dosage of nano-TiO2/CaCO3 was recommended as 5% by weight of base bitumen. Adding nano-TiO2/CaCO3 was beneficial to improve the viscosity and reduce the temperature sensitivity of bitumen. The capacities of bituminous rutting resistance as well as medium-temperature fatigue resistance were enhanced by the addition of nano-TiO2/CaCO3. However, BBR test shows that bituminous anticracking is reduced slightly. On this basis, the Burgers model is selected for clarifying the decrease in anticracking performance; that is, nano-TiO2/CaCO3 increased the stiffness modulus while increasing the viscosity of bitumen. [ABSTRACT FROM AUTHOR]

Moisture damage is known to be a key factor influencing the durability of asphalt pavements. This phenomenon will reduce the mechanical properties of asphalt mixtures due to its destructive effects on the adhesion of the bitumen-aggregate system and the cohesion of the bitumen membrane. The mineral properties of the aggregates of asphalt mixtures are one of the factors affecting moisture susceptibility. Therefore, the surface free energy (SFE) method, as one of the thermodynamic methods, and indirect tensile strength test (ITST) have been used to determine the failure mechanism and the rate of change of adhesion properties of asphalt mixtures under the influence of mineralogical characteristics. Prior to the above tests, an X-ray fluorescence spectrometry (XRF) test was performed to identify aggregate-forming minerals in eight different types of aggregates with various minerals from eight mines, and also the apparent bitumen film thickness was measured. XRF test results showed that most parts of the aggregates in mines 1– 6 were composed of SiO2, which had strong acidic properties, according to the SFE results. ITST results showed that samples constructed with aggregates of mine 7 and 8 (with high CaO mineral content) experienced a higher TSR than other mixtures in all freeze-thaw (F-T) cycles. Results of the SFE method showed that aggregates with more calcareous properties had a smaller acidic component and a larger basic component. In mines 7 and 8, where the nonpolar component of their aggregates was larger, the tendency of the aggregates to adherence and wettability by water decreased. The adhesion free energy (AFE) between bitumen and aggregates with higher CaO and less SiO2 amounts was more than AFE between bitumen and aggregates with lower CaO and higher SiO2 amounts, in dry conditions. The presence of higher amounts of CaO in aggregates increased AFE of bitumen-aggregate in presence of water from a negative value to zero. In linear regression analysis, due to the positive regression coefficient of the CaO mineral, this mineral had a positive impact on TSR; on the other hand, due to the negative regression coefficient of the SiO2 mineral, this mineral had a negative impact on the TSR of asphalt mixtures. [ABSTRACT FROM AUTHOR]

Nanomaterials have a great potential for enhancing the performance of base asphalt binder. This study aims to promote the application of nano-TiO2/CaCO3 in bitumen and presents a study on rheological properties for TiO2/CaCO3 nanoparticle-bitumen. In this study, a series of laboratory experiments have been performed for bitumen with different nano-TiO2/CaCO3 dosages. Nano-TiO2/CaCO3-modified bitumen with optimum dosage was prepared for viscosity, dynamic shear rheometer (DSR), and beam bending rheometer (BBR) for assessing temperature sensitivity of bitumen, and the low-medium-high-temperature performances were analyzed for TiO2/CaCO3 nanoparticle-bitumen as well. Results show that bituminous mechanical properties were enhanced by TiO2/CaCO3, and based on the overall desirability analysis of various conventional tests, the reasonable dosage of nano-TiO2/CaCO3 was recommended as 5% by weight of base bitumen. Adding nano-TiO2/CaCO3 was beneficial to improve the viscosity and reduce the temperature sensitivity of bitumen. The capacities of bituminous rutting resistance as well as medium-temperature fatigue resistance were enhanced by the addition of nano-TiO2/CaCO3. However, BBR test shows that bituminous anticracking is reduced slightly. On this basis, the Burgers model is selected for clarifying the decrease in anticracking performance; that is, nano-TiO2/CaCO3 increased the stiffness modulus while increasing the viscosity of bitumen. [ABSTRACT FROM AUTHOR]

The construction of suitable roads in rainy areas has created problems in the construction process due to the low resistance of asphalt to moisture. To solve this problem, materials are commonly used that make mixtures resistant to moisture; however, these materials may reduce the dynamic resistance of asphalt. Therefore, materials should be used that, in addition to increasing the dynamic resistance, also increase the moisture resistance of asphalt mixtures. One of these materials used in this research is steel wool fiber (SWF), which in addition to creating conductive roads also could have a significant effect on moisture resistance. In this study, the impact of 2%, 4%, 6%, 8%, and 10% SWF on the Marshall stability and moisture sensitivity of mixtures was investigated using the Marshall stability and indirect tensile strength (ITS) tests, respectively. Moreover, using SWF as a conductive fiber, the conductivity properties of asphalt mixtures were explored to find the optimal amount of electrical conductivity. The results of the Marshall stability test indicated that by increasing SWF contents, the stability of mixtures increased, compared with the base sample, and greater amounts of 6% SWF resulted in the reduction of the Marshall stability. The results of ITS showed that modification of bitumen by SWF increased ITS and tensile strength ratio (TSR) amounts of mixtures. 6% SWF was the optimal amount for enhancing the resistance of asphalt mixtures to moisture sensitivity. The results of the electrical resistivity test showed that the resistivity had three phases: high resistivity, transit, and low resistivity. Mixtures containing less than 4% SWF illustrated an insulating behavior, with electrical resistivity greater than 7.62 × 108 Ω. m. At the transit phase, the resistivity of mixtures had a sharp reduction from 7.62 × 108 Ω. m to 6.17 × 104 Ω. m. Finally, 8% SWF was known as the optimal content for the electrical conductivity of mixtures. [ABSTRACT FROM AUTHOR]

Growing economy and increasing pollution evoke the need for more environmentally friendly road construction techniques and the saving of natural resources. In this context, cold recycling plays an important role since, on the one hand, it allows to reduce CO2 emissions drastically and, on the other hand, it offers a variety of opportunities for high percentages of recycling. Inspired by experience in Sweden, the international project "Optimal Recycling of Reclaimed Asphalts for low-traffic Pavement" (ORRAP) for low-volume roads in the Upper Rhine region aims to develop and establish a new strategy for 100% reclaimed asphalt pavement (RAP) at ambient temperature (20°C) without adding virgin bituminous binders or rejuvenators. The still ongoing research project involves laboratory experiments as well as in situ test sections. The link between small-scale laboratory experiments and in situ testing is provided by medium-scale traffic simulation in the laboratory. This paper describes results from medium-scale compaction in the laboratory using different methods as well as traffic simulation with a medium-scale mobile traffic load simulator. The results show that compaction in the laboratory at ambient temperature (20°) is very difficult to achieve. Nevertheless, it was found that compaction at a temperature of 60°C appears possible and provides promising results regarding stability and rutting enabling the in situ construction. The in situ pavement construction at ambient temperature on a low-volume road in Switzerland resulted in a visibly well-compacted and stable base course which was covered by a hot mix asphalt surface course the day after. The test section will be monitored closely over the next 12 months. [ABSTRACT FROM AUTHOR]

The use of reclaimed asphalt pavement is a practice that is adding significant environmental value to road technologies, not only due to the reduction of materials sent to landfill but also because of the mechanical properties of the reclaimed asphalt (RA) that can be reused. This research focuses on the rheological properties of hot and cold bituminous mastics made up as follows: (1) hot mastics mixed with limestone filler (LF) and bitumen, (2) hot mastics, made from bitumen mixed with jet grouting waste (JW), a mixture of water, cement, and soil derived from land consolidation work in underground tunnels, and (3) hot mastics mixed with LF and JW as filler and bitumen. Three different ratios (0.3, 0.4, and 0.5) of filler per unit of neat bitumen (B50/70) were studied. The same number was used for mixing cold mastics, by using an appropriate laboratory protocol designed since the adoption of a cationic bituminous emulsion. A total of 18 mastics were prepared and investigated. The comparison was carried out using the frequency sweep (FS) test, analysing shear modulus G ∗ , applying the multistress creep and recovery (MSCR) test (40°C and 60°C) as well as the delta ring and ball (ΔR&B) test, focusing on two main issues: (1) the stiffening effect caused by the filler type used for mixing each mastic, and (2) a comparison, in terms of stiffening effects and nonrecoverable creep compliance (Jnr) of hot and cold mastic performance to highlight JW reuse in mastics. The results showed that the best G ∗ performance at test temperatures higher than 30°C is given by cold mastic after 28 days of curing time when JW is added to LF and bitumen. The lowest Jnr value was 40°C and 60°C for the same mastic. [ABSTRACT FROM AUTHOR]

The development of non‐black asphalt mixtures for surface courses may play a significant role to improve functional, aesthetic and environmental issues of road pavements. Nowadays, the development of clear binders as substitutes for traditional bitumen in asphalt mixtures, which combine durability and mechanical properties, exalting the color of pavements for a better integration of road networks in urban and environmentally sensitive areas, is undoubtedly a timing challenge. However, the selection and classification of clear binders are often based only on color and standard requirements referred to traditional bitumen that do not describe consistently the binder behavior. A better understanding on clear binder properties is required to guide the aggregate selection and the mix design for surface layer, merging safety, aesthetical and environmental benefits into long lasting pavement. This paper presents a comprehensive experimental program, including empirical tests, infrared spectrum analysis, and rheological testing over a wide range of temperature and frequency, to determine the overall mechanical behavior of three clear binders. Results highlighted that the selected clear binders differ from traditional bitumen in terms of mechanical behavior. Different composition or origin can induce to completely different performance. Moreover, the combination of several testing procedures allowed suggesting specific application methods and uses for the three clear binders. [ABSTRACT FROM AUTHOR]

The objective of this study is to analyse the differences between experimental LVE properties of both a straight-run bitumen and a bituminous mixture and simulations with analogical 2S2P1D (2 Springs, 2 Parabolic elements, and 1 Dashpot) model fitted by 14 different users. Data for the bitumen consisted of isotherms of G∗ and φ obtained from DSR complex modulus tests at 12 different temperatures ranging from −29.9°C to 60.0°C and frequencies ranging from 6.3 to 40 Hz, for a total of 60 data points. Data for the bituminous mixture consisted of isotherms of E∗ and φ obtained from strain-controlled traction/compression complex modulus tests at 8 different temperatures ranging from −29.7°C to 38.8°C and frequencies ranging from 0.01 to 10 Hz, for a total of 55 data points. All users worked independently and for the same time duration of one hour to fit the 2S2P1D model on both sets of data. Successful simulations of experimental data of both bitumen and mixture were generally obtained by all the users over the whole range of frequencies and temperatures, regardless of their familiarity and experience with the model. The accuracy of the model to fit experimental data is all the more evident if the great spans of complex modulus (G∗ of the bitumen between 10−2 and 103 MPa, E∗ of the mixture between 10 and 40000 MPa) are considered. The obtained results highlight the convenience of 2S2P1D model to perform multiscale modelling of LVE behaviour of bituminous materials, from bitumens to mixtures. [ABSTRACT FROM AUTHOR]

Here, we develop a model predicting the dynamic moduli of hot-mix asphalt/concrete using the extended Kalman filter (EKF) algorithm and draw frequency-domain master curves. Discrete dynamic moduli were obtained via impact resonance tests (IRTs) on linear viscoelastic (LVE) asphalt at 20, 30, 35, 40, and 50°C. Typically, viscoelastic characteristics have been used to derive asphalt dynamic moduli; compressive frequency sweep tests at different frequencies (Hz) and temperatures are employed to this end. We compared IRT-derived viscoelastic master curves obtained via compressive frequency sweep testing to those derived using the EKF algorithm, which employs a nonlinear sigmoidal curve and a Taylor series to explore the viscoelastic function. The model reduced errors at both low and high frequencies by correcting the coefficients of the master curve. Furthermore, the predictive model effectively estimated dynamic moduli at various frequencies, and also root-mean-square errors (RMSEs) which, together with the mean percentage errors (MPEs), were used to compare predictions. [ABSTRACT FROM AUTHOR]

Starting from the eighties, the use of nanoadditives registered an increasing attention in the scientific and patent literature, especially for the case of polymeric nanocomposites. In the last decade, this involved bituminous materials, modified either with nanosized fillers or with polymeric nanocomposites. One of the expected benefits is an increased resistance of the binder to aging. After a short introduction underlining the uncertainties and risks of artefacts in aging tests, a review is given, focusing on the antiaging properties of layered silicates, which are by far the most important nanoadditives for bitumens. Together with layered silicates, other materials such as nanohydrated lime, nanosilica, and layered double hydroxides are mentioned. Preparation and characterization of the binary bitumen/layered silicate and ternary bitumen/layered silicate/polymer systems are described in order to individuate the aspects that influence the antiaging effect. Even if the available literature is quite abundant and unanimously confirms that nanoadditives may improve bitumen durability, there is a lack of studies clarifying the involved mechanisms. As it is for conventional fillers, it seems to be a combination of physical and chemical interactions. Nanoadditives with different chemistries, porosities, and interlayer spacings differently absorb the polar components from the bitumen, thus affecting their predisposition to oxidative aging. [ABSTRACT FROM AUTHOR]

Determining the influential factors of noise characteristics in dense-graded asphalt mixtures and field asphalt pavement is important in constructing highways that are both low noise and environmentally friendly. In this study, the effects of nominal maximum aggregate size, asphalt binder type, air void percentage, and the service life of pavement on the noise absorption characteristics of asphalt mixtures were first investigated in laboratory. Thereafter, tire/pavement noise measurements were conducted on different types of dense-graded asphalt pavements. The effects of the service lives of the pavements, the types of the pavements, driving speeds, and test temperatures on the noise levels of the pavements were also studied. The Zwicker method is used to calculate psychoacoustic parameters on the tire/pavement noise spectrum. The laboratory results indicate that reducing the nominal maximum aggregate size, using rubber asphalt, and increasing air void percentage as well as surface texture depth improve the sound absorption performance of asphalt mixtures. The field measurements show that laying down asphalt pavements with a shorter service life or larger texture depth, using rubber asphalt, reducing traffic speed, and increasing air temperature can reduce noise. [ABSTRACT FROM AUTHOR]

This study intended to evaluate the use of waste stone sawdust filler with asphalt binders and compare the mechanical properties of the waste filler-asphalt mastic with those of the asphalt mastic produced using the typical limestone filler. The mastics were prepared at four filler-to-asphalt ratios by volume of asphalt binder: 0.05, 0.10, 0.20, and 0.30. A dynamic shear rheometer (DSR) strain-controlled frequency sweep test was used to evaluate the properties of the control asphalt binder and the mastics. The test used a constant strain of 10% and loading frequencies of 10, 5.6, 3.1, 1.78, 1.0, 0.56, 0.31, 0.178, and 0.1 Hz and was conducted at wide range of temperatures: 10, 20, 30, 40, 50, 60, and 70°C. The test measured the complex shear modulus (G∗) value and the phase angle for the binder and the mastics. The findings of this study showed that the stone sawdust filler demonstrated higher resistance to fatigue and rutting behavior than the limestone filler. However, the elastic behavior of the two asphalt mastics was nearly similar and increased with the increase in volume ratio. It was also found that the best-fit model described the relationship between the volume ratio and each of G∗/sin  δ and G∗cos δ, and the mastic-to-binder modulus ratio was the exponential model with high coefficient of determination (r2). The differences in the G∗ value between the limestone filler and the stone sawdust filler were relatively insignificant particularly at low loading frequencies and high temperatures. Finally, the mastic-to-binder modulus ratio decreased with the increase in loading frequency. [ABSTRACT FROM AUTHOR]

Based on the Particle Flow Code in Two dimensions (PFC2D), an algorithm for modeling the two-dimensional virtual asphalt mixture was proposed in this study. By combining the AIMS scanning technology (Aggregate Imaging Measurement System) with the designed stochastic algorithm, the virtual coarse aggregates could be generated rapidly and precisely. Different from the conventional methods, the contour shapes of the coarse aggregates were rebuilt only to balance the shape modeling precision and simulation efficiency. Then by distributing the coarse particles within container, virtual skeletons were formed firstly. An innovate algorithm was proposed afterwards to distinguish the external and internal area of the coarse aggregates and then model the mastic part by filling the irregular hollow shape with uniformly arranged balls. By deleting the mastic balls randomly, the voids were reconstructed consistent with the actual ratio. In the end, the virtual uniaxial compressive tests of AC-16 were simulated within PFC2D and the dynamic modulus at different load frequencies was predicted. The results indicated that the proposed algorithm could not only model the asphalt mixture precisely but also characterized its mechanical behavior as well. [ABSTRACT FROM AUTHOR]

Gravel roads play an important role in the transport infrastructure. However, their maintenance (especially the control of dustiness using chemical dust suppressants) is expensive. Besides, the condition of gravel roads results in low driving comfort, longer travelling time, faster vehicle amortization, and so forth. Typically, these problems are solved by paving gravel roads with asphalt wearing layer. However, north countries practice had shown pavement structure high susceptibility to frost due to insufficient thickness of frost resistance layer. The construction of thicker frost resistant layer increases road construction cost by 25% and, in most cases, there is no need to increase bearing capacity by increasing total thickness of pavement structure. In 2012 19 gravel roads were constructed using cost effective rehabilitation technologies—soft asphalt and double Otta Seal in Lithuania. This paper focuses on those two technologies’ performance within first three years of constructed roads exploitation. The implemented experimental research consisted of three parts by evaluating constructed roads base layers bearing capacity; pavement roughness; and pavement distresses and defects. As a result, the acceptable performance indicators were determined for both technologies—soft asphalt and double Otta Seal. Also recommendations for construction and exploitation improvement were defined. [ABSTRACT FROM AUTHOR]

There are different places in India where natural stone aggregates are not available for constructional work. Plastic coated OBBA can solve the problem of shortage of stone aggregate to some extent. The engineers are always encouraged to use locally available materials. The present investigation is carried out to evaluate the plastic coated OBBA as an alternative material for bituminous road construction. Shredded waste plastics are mixed with OBBA in different percentages as 0.38, 0.42, 0.46, 0.50, 0.54, and 0.60 of the weight of brick aggregates. Marshall Method of mix design is carried out to find the optimum bitumen content of such bituminous concrete mix prepared by plastic coated OBBA. Bulk density, Marshall Stability, flow, Marshall Quotient, ITS, TSR, stripping, fatigue life, and deformations have been determined accordingly. Marshall Stability value of 0.54 percent of plastic mix is comparatively higher than the other mixes except 0.60 percent of plastic mix. Test results are within the prescribed limit for 0.54 percent of plastic mix. There is a significant reduction in rutting characteristics of the same plastic mix. The fatigue life of the mix is also significantly higher. Thus plastic coated OBBA is found suitable in construction of bituminous concrete road. [ABSTRACT FROM AUTHOR]

Bituminous geomembranes, one type of geosynthetics, include a hot bituminous mixture with mineral filler and reinforcement. In this study, boron production waste clay (CW) was used as filler to produce a geosynthetic barrier with bentonite, waste tire, and bitumen. Bentonite and waste tires were used as auxiliary fillers and bitumen as the binder. CW/bitumen, CW/bentonite/bitumen, and CW/waste tire/bitumen mixtures were prepared by using a laboratory mixer at 100°C. Hot mixtures were extruded into strips by using a lab-scale corotating twin screw extruder (L/D: 40) followed by die casting (2 mm × 100 mm). Glass fleece or nonwoven polyester was used as reinforcement material and while die casting, both sides of the reinforcement materials were covered with bituminous mixture. Thickness, mass per unit area, tensile strength, elongation at yield, and hydraulic conductivity were used to characterize the geomembranes. Among all geomembranes, nonwoven polyester covered with 30% bitumen-70% boron waste clay mixture (PK-BTM30CW70) was found to be the most promising in terms of structure and mechanical behaviour. After that, consequences of its exposure to distilled water (DW), municipal solid waste landfill leachate (L-MSW), and hazardous waste landfill leachate (L-HW) were examined to use for an innovative impermeable liner on solid waste landfills. [ABSTRACT FROM AUTHOR]

The paper describes an investigation into mechanical properties of brick-stone bituminous concrete mix. The effect of brick-stone mix on various mechanical properties of the bituminous concrete such as Marshall stability, flow, Marshall Quotient (stability to flow ratio), Indirect Tensile Strength, stripping, rutting, and fatigue life of bituminous concrete overlay has been evaluated. In this study over-burnt brick aggregate (OBBA) and stone aggregate (SA) have been mixed in different ratios (by weight) such as 20 : 80, 40 : 60, 60 : 40, and 80 : 20, respectively. The laboratory results indicate that bituminous concrete, prepared by 20% brick aggregate and 80% stone aggregate, gives the highest Marshall stability. This bituminous concrete mix shows considerable improvement in various mechanical properties of the mix as compared to the other mixes. [ABSTRACT FROM AUTHOR]

By means of limiting oxygen index (LOI), cone calorimeter, and TG-DSC tests, this paper investigated the effect of unmodified montmorillonite (MMT), organically modified montmorillonite (OMMT), and aluminium trihydrate (ATH) additions on the flame retardancy for asphalt combustion. Experimental results showed that adding a small amount of montmorillonite did not significantly increase the oxygen index of the asphalt but reduced the heat release rate during asphalt combustion. TGA tests had indicated that the montmorillonite (MMT and OMMT) could suppress the release of flammable volatiles and form more asphaltenes, which hence postponed the burnout time of asphalt. Furthermore, the combination of montmorillonite (MMT and OMMT) and ATH had yielded a synergistic effect, which had further reduced the heat release rate and also increased the oxygen index of asphalt. In particular, after further addition of OMMT, the barrier layer showed less crack, leading to a significant decrease in the heat release rate as compared to the adding of ATH alone. [ABSTRACT FROM AUTHOR]

Recycled concrete aggregate (RCA) is considered as one of the largest wastes in the entire world which is produced by demolishing concrete structures such as buildings, bridges, and dams. It is the intention of scientists and researchers, as well as people in authority, to explore waste material recycling for environmental and economic advantages. The current paper presents an experimental research on the feasibility of reusing RCA in stone mastic asphalt (SMA) mixtures as a partial replacement of coarse and fine aggregates. The engineering properties of SMA mixtures containing RCA have been evaluated for different percentages of binders based on the Marshall mix design method. The outcomes were statistically analyzed using two-factor analysis of variance (ANOVA). Test results revealed that the performance of SMA mixtures is affected by RCA due to higher porosity and absorption of RCA in comparison with virgin granite aggregates. However, the engineering properties of SMA mixtures containing a particular amount of RCA showed the acceptable trends and could satisfy the standard requirements. Moreover, to achieve desirable performance characteristics, more caution should be made on properties of SMA mixtures containing RCA. [ABSTRACT FROM AUTHOR]

This study investigated the influence of layered double hydroxides (LDHs) on the fatigue properties of asphalt mixture. In this paper, different aging levels (thin film oven test (TFOT) and ultraviolet radiation aging (UV aging for short)) of bitumen modified with various mass ratios of the LDHs were investigated. The TFOT and UV aging process were used to simulate short-term field thermal-oxidative aging and long-term field light UV aging of bitumen, respectively. The influences of LDHs on the fatigue properties of LDHs were evaluated by dynamic shear rheometer (DSR) and indirect tensile fatigue test. Results indicated that the introduction of LDHs could change the fatigue properties of bitumen under a stress control mode. The mixture with modified bitumen showed better fatigue resistance than the mixture with base bitumen. The results illustrated that the LDHs would be alternative modifiers used in the bitumen to improve the lifetime of asphalt pavements. [ABSTRACT FROM AUTHOR]

Uniaxial compression test of cement asphalt (CA) mortar specimens, due to drying and wetting cycle of 0, 2, 4 and 8 times, is carried out by using the electronic universal test machine, with the strain rate ranging from 1 x 10-5 s-1 to 1 x 10-2 s-1. The effects of strain rate and drying and wetting cycle time on the compressive strength, elasticity modulus, and stress-strain full curve are investigated. Experimental results show that the strain-stress full curve of CA mortar is affected obviously by strain rate and drying and wetting cycle time. The compressive strength and elasticity modulus increase with the strain rate under the same drying and wetting cycle time. The compressive strength and elasticity modulus decrease with the increase of drying and wetting cycle time in the same strain rate. The lower the strain rate is, the greater the compressive strength and elasticity modulus of CA mortar decrease. When the strain rate is 1 x 10-5 s-1 and drying and wetting cycle time is 8, the largest reduction of average compressive strength of CA mortar is 40.48%, and the largest reduction of elasticity modulus of CA mortar is 35.51%, and the influence of drying and wetting cycle on the compressive strength of CA mortar is greater than its influence on the elasticity modulus. [ABSTRACT FROM AUTHOR]

Deformation properties and fatigue performance are important characteristics of asphalt bound materials which are used for construction of pavement layers. Viscoelastic asphalt mixtures are better characterized via dynamic tests. This type of tests allows us to collate materials with regard to axle vibrations which lie usually in the range of 6Hz-25Hz for standard conditions. Asphalt modified for heat sensitivity in the range from -20°C to +60°C has significant impact on the overall characteristics of the mixture. Deformation properties are used as inputs for empirical mixture design, and fatigue performance of asphalt mixtures reflects the parameters of functional tests. Master curves convey properties of asphalt mixtures for various conditions and allow us to evaluate them without the need of time expensive testing. [ABSTRACT FROM AUTHOR]

Today, virgin polymer modified asphalt mixes are comparatively more expensive for road pavement. One way to reduce the expense of such construction and to make it more convenient is the application of inexpensive polymer, such as waste polymer. The primary aim of this study was to investigate the effect of adding waste tyre rubber (crumb rubber modifier (CRM)) on the stiffness and fatigue properties of stone mastic asphalt (SMA) mixtures. Various percentages of waste CRM with size of 0.60mm were added to SMA mixtures. Indirect tensile stiffness modulus test was conducted at temperatures of 5, 25, and 40°C. Indirect tensile fatigue test was conducted at three different stress levels (2000, 2500, and 3000 N). The results show that the stiffness modulus of reinforced SMA samples containing various contents of CRM is significantly high in comparison with that of nonreinforced samples, and the stiffness modulus of reinforced samples is in fact less severely affected by the increased temperature compared to the nonreinforced samples. Further, the results show that CRM reinforced SMA mixtures exhibit significantly higher fatigue lives compared to the nonreinforced mixtures help in and promotion of sustainable technology by recycling of waste materials in much economical and environmental-friendly manner. [ABSTRACT FROM AUTHOR]