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The article presents the chemical composition of vermiculite ores from the Kulantau deposits and the atomic structure of vermiculite during dehydration, in 1-, 2- and 3-layer hydrated states. It has been shown that vermiculites from deposits in the Turkestan region have significant differences in mineralogical composition. Rational ways of using Kulantau vermiculite as an innovative modifying additive in bitumen compositions are considered, which are intended to improve the asphalt concrete mixture during its preparation. A slight increase in structuring resins is a result of the elevated content of high-molecular-weight asphaltenes in the modified bitumen, as indicated by the analysis of the provided spectra. In turn, the systematization or structuring of bitumen leads to an increase in the mixture density, accompanied by a simultaneous rise in internal friction coefficients, and resistance to loads (shear and impact), as well as an enhancement in compressive strength. The influence of the chemical composition of Kulantau vermiculite on the structure of bitumen compositions is characterized by high adsorption capacity and effectively absorbs products resulting from the oxidation of hydrocarbons. Vermiculite is characterized by high efficiency in the activation phase, large pore volume, and selectivity. The alteration of the bitumen's group composition due to the selective diffusion of oils, as well as resins in the material, occurs as a result of the interaction between bitumen and a material characterized by a fine-porous structure and high specific surface area. This process modifies the properties of bituminous layers on the surface of particles and leads to the formation of robust bitumen films appearing on the grain surfaces. Thus, enhancing the longevity of coatings, improving the quality of binding bitumen, and reducing asphalt concrete coverings necessitate the use of vermiculite in creating modified bituminous compositions. [ABSTRACT FROM AUTHOR]

Considering the global burden of cigarette consumption, the disposal of cigarette butts has become an inevitable issue. Compared to traditional disposal methods, such as landfilling or incinerating, the recycling of these wastes is clearly an eco-friendlier solution. In this research, waste electronic cigarette butts (E-CBs) were collected and recycled in bituminous mixtures, aiming to increase the use of sustainable road construction materials. The objective of this research is to explore the possibility of using waste E-CBs as an alternative stabilising fibre in asphalt mixtures. To this end, shredded waste E-CBs were incorporated in Stone Mastic Asphalt (SMA) and compared with the conventional cellulose fibres. Furthermore, to investigate the effects of powders (below 0.063 mm) from the waste E-CBs on the rheological properties of bitumen, tests were conducted on base SBS-modified bitumen and its mastics. Results show that the waste powder was unfavourable to the thermal susceptibility of the resulting binder. SMA samples with shredded E-CBs were also characterised through physical and mechanical tests and compared to the reference mixture using cellulose fibres. It was concluded that using waste E-CBs in SMA can be considered a promising alternative for replacing cellulose fibres and avoiding the disposal of cigarette butts. [ABSTRACT FROM AUTHOR]

In this study, the low temperature creep properties of multiphase bituminous materials (binder, mastic, Fine Aggregate Matrix—FAM, and mixture) were experimentally evaluated, and the impact of size effect on FAM and mixture specimen was also assessed. First, the mix design of mastic and FAM was performed based on the reference mixture Asphalt Concrete (AC) 22 TS. The mathematical adaptation to the boundary sieve method was applied to calculate FAM gradation and binder content. Next, a preparation method was proposed to produce Fine Aggregate Matrix (FAM) in a laboratory environment, and scale-up slab samples were also fabricated for FAM and mixture specimens to evaluate the size effect phenomenon. Finally, three-point bending (3 PB) creep tests were conducted on the multiphase bituminous specimens with different dimensions at -6 °C, -12 °C, and -18 °C with a modified Bending Beam Rheometer (BBR) device and a dynamic loading machine, depending on the sample size. Results indicate that the creep stiffness of the FAM was close to mixtures and much higher than the one observed in binder and mastic. The proposed fabrication approach provides a satisfactory method for preparing a representative FAM phase in the mixture, while the air voids can be easily adjusted during the slab compaction procedure. This study supports the idea of using FAM to discriminate asphalt mixtures for cold regions. The correlation between up-scaled FAM and mixture specimens should be further investigated, including different mixture types and corresponding FAM. [ABSTRACT FROM AUTHOR]

Hot- and cold-applied joint sealants are materials commonly used for the surface repairs of the upper layers of asphalt or concrete road surfaces. Our investigations covered six hot-applied joint sealants, classified as the high-extension type N1 (elastic) or low-extension type N2 (normal), in accordance with the standard EN 14188-1; the sealants were obtained commercially from four European manufacturers. The present paper focuses on the characterization of the consistency of the joint sealants, the bituminous binders that contain them, and the characterization of their insoluble components. Additional testing methods included an FTIR analysis of the sealants and the extracted binders, as well as SEM, EDS, and sieving analyses of the insoluble material. Joint sealants are complex formulations and include a broad range of base asphalt binders and other components. Their compositions may vary widely, while still fulfilling the performance specifications. Through the extraction of the solvents and the separation of the crack sealants, it was found that radically different compositions of crack sealants resulted in the comparatively similar performance of the tested material. The EDS and FTIR analysis methods provided insights into the composition of the crack sealants and the types of mineral materials used. [ABSTRACT FROM AUTHOR]

Mix design of asphalt concrete is carried out in order to produce a mixture of asphalt bitumen and aggregate that satisfies both minimum design requirements and cost-effectiveness. Marshall mix design, similar to other mix design methods, aims to determine an optimum mix for a given design criteria, having an optimum bitumen content, and has still been one of the most used asphalt mix design method in the world. Marshall mix design procedure requires significant amount of time and skilled workmanship for lengthy laboratory experiments. Time required for the mix design may negatively affect construction schedule especially during the peak construction season. In Marshall mix design procedure, optimum bitumen content is determined based on Marshall stability and flow test results, and other volumetric properties of the mixes. Prediction models that quickly predict all required Marshall mix design parameters based on very few numbers of input parameters requiring significantly less amount of time to obtain compared to the time needed to obtain all Marshall mix design parameters through lengthy laboratory experiments could be quite useful. In this study, artificial neural network-based prediction models based on the data of 200 asphalt mixes designed for asphalt wearing course, obtained from 5th district of the General Directorate of Highways of Turkey, were developed to predict all required Marshall mix design parameters. As part of the paper, a Microsoft Excel Macro-based tool, to be potentially used by 5th district of the General Directorate of Highways of Turkey, was also developed that makes prediction of all required mix design parameters for any given mix in seconds using the developed models and very few numbers of user-defined input parameters requiring significantly less amount time to obtain so that optimum bitumen content could be quickly determined. This will significantly reduce the amount of time and other resources required to determine optimum bitumen content. [ABSTRACT FROM AUTHOR]

In previous studies, different additives and modifiers have been studied to improve the properties of asphalt concrete mixtures, whose main failures are plastic deformation and cracking. In this research, the improvement of the properties of asphalt concrete mixtures were investigated by introducing residual plastics as a substitute for virgin bitumen, which improves the sustainability of the mixtures. Furthermore, the results obtained from these new mixtures were compared with a mixture designed with polymer-modified bitumen (PMB). Ten experimental designs were tested with three types of waste fibre plastics from a municipal solid waste treatment plant and two percentages of bitumen replacement (15% and 25%). The experimental testing plan included air void characterization, moisture sensitivity, stiffness and fatigue resistance, among others. An increase of approximately 5% in voids could be observed when introducing the plastic material and therefore some tests were carried out to over-compact the specimens. The results showed an improvement in the mechanical performance of the experimental mixtures, highlighting the resistance against plastic deformations, which even reached similar values to the mixtures made with PMB. [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]

In order to use the natural resources in our country efficiently, effectively and for a longer time, it is becoming more important to research and find alternative materials. As in every field, the use of waste materials in bituminous hot mixes is increasing day by day. In this study, the usability of waste serpentine dust wastes as fillers in HMA was investigated. In the study, the usability of serpentine as filler in asphalt concrete pavements was investigated. For this purpose, Marshall briquettes were prepared with bitumen ratios of 3.5-4.0-4.5-5.0-5.5-6.0% by using limestone aggregate and crushed stone dust filler. By applying Marshall stability and flow test procedure to these prepared samples, stability, flow value, bulk specific gravity (Dp), void volume values (Vh), Void filled with asphalt (Vfa), voids in mineral aggregate (VMA) values were found. Optimum amount of bitumen was determined by drawing related graphs from the limestone sample results. Based on the optimum amount of bitumen determined and using the same gradation, limestone filler and serpentine filler material were replaced at the rate of 0-25-50-75-100%, and serpentine-substituted asphalt concrete samples were produced. The stability, yield, Dp, Vh, Vfa, VMA values of the serpentine filler substituted briquettes were determined and the test results were evaluated. As a result of the study, the highest stability value was obtained from the samples with %50 serpentine content. [ABSTRACT FROM AUTHOR]

Polymers are used worldwide for their unique properties such as a light weight or chemical resistance, but which have led to an environmental challenge because of the time they need to completely decompose when buried in landfills. Complementarily, bitumen generates the second biggest environmental impact in the construction of a road. This paper analyses the mechanical, environmental and economic performance of replacing 25% of bitumen with two low-cost plastic wastes (cable plastic and the film fraction from household packaging waste) in an asphalt mixture. The results demonstrated the feasibility of the technology from the 3 viewpoints analysed. The plastic-modified mixtures achieve reductions of more than 17% and 11% in the economic and environmental impact when the analysis is focused on the wearing course. [ABSTRACT FROM AUTHOR]

It is widely admitted that the repeated passage of heavy goods vehicles as well as environmental conditions are the main causes of damage to road structures. This sometimes requires the use of rehabilitation techniques to maintain the road in operational and safe condition and extend its life. The current trend in the world is to find new low cost materials that are able to guarantee the best performance of pavements; the Roller Compacted Concrete (RCC) is a good example. This work is mainly concerned with the use of more rigid local materials in the construction of roads and their placement by compaction instead of flexible asphalt concrete wearing courses which have been shown several drawbacks. Indeed, flexible asphalt concrete wearing courses become softer under heavy traffic and require a very expensive bituminous material supply. It is therefore urgent today to find cost-efficient road construction techniques that can combine durability and hardness. The strategy used in this research consists, on the one hand, in making a roller compacted concrete made of recycled aggregates using materials from local deposits with a low dosage of cement, and on the other hand, to validate this study numerically by evaluating the maximum compressive strength and then to model the cracked sections of roller compacted concrete containing recycled aggregates in order to develop a new method that allow minimizing the degradation of pavements. This would certainly make the present research paper more original. The results obtained allowed to find that it is quite possible to manufacture roller compacted concrete with partial incorporation of recycled aggregates with compressive strength acceptable and approximately equal to 34 MPa at 28 days. This type of RCC is more resistant and less dangerous because recycled aggregates improve the behavior of pavements, especially in the presence of cracks where we found that the stress intensity factor for RCC with natural aggregates (− 1.1631 MPa√m) is greater than in RCC with recycled aggregates (− 0.4989 Mpa√m). [ABSTRACT FROM AUTHOR]

As materials undergo large-scale yielding or exhibit large sizes of fracture process zone in the crack tip region, multi-parameter fracture concepts should be employed to describe the complex crack-tip stress-strain fields. Fracture resistance curves (R-curves) are an established tool in characterizing the entire fracture process of such materials. However, for complex materials such as bituminous mixtures, the development of these curves is subject to experimental and computational intricacies. In this research, a framework is developed to automate the construction of R-curves for normal and rubberized asphalt concrete (AC) mixtures. AC mixtures are produced using PG58–22 and PG58–28 binders. Limestone and siliceous aggregates are used, and three binder contents are considered for the mixtures. Single-edge notched beam (SE(B)) fracture testing is conducted on AC beams with two different notch patterns. A convolutional neural network (CNN) model is developed and trained over 1260 test images with varying temperatures, notch geometries, and setups. The CNN model was used to detect the growing crack on the beam surface and each crack-detected image was sent to an image processing framework to measure the crack length. Crack extension increments were calculated and synchronized with test time and magnitude of load, load-line displacement, and cumulative fracture energy, and the R-curve could be constructed. A training accuracy of 0.91 was obtained for the model and a loss of below 0.10 as a result of a hyperparameter tuning indicating reliable classifications by the CNN architecture. The R-curves showed desirable agreement for control mixtures at temperatures of 0 °C and −15 °C. As the mixtures are rubberized, the R-curves showed favorable agreement in the crack blunting phase, transition zone, as well as the unstable propagation phase at −20 °C. Cohesive energy magnitudes were compared for the two methods with a Pearson coefficient of 0.81 while fracture rate and fracture energy magnitudes showed favorably close magnitudes with coefficients of 0.89 and 0.98 respectively. • R-curves of asphalt concrete mixtures were constructed using an automated procedure. • Image data pre-processing is conducted using CNN to classify images containing cracks. • The accuracy of the CNN model was enhanced to 0.91 after hyperparameter tuning. • The R-curves for rubberized mixtures were desirably close in all fracture phases. [ABSTRACT FROM AUTHOR]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

(i) Recycled and renewable materials in asphalt pavements may be employed for the modification of asphalt binders and/or for the full or partial replacement of natural aggregates and mineral filler in asphalt mixtures [[1]]. A sustainable approach in asphalt pavement engineering should focus on materials, design methods, and technologies that can contribute to minimizing environmental impacts through a reduction in energy consumption and natural resources, while ensuring that all performance standards and requirements are met. By comparing the performance of various binders based on Zero Shear Viscosity (ZSV), grey relational analysis showed the highest correlation with an anti-rutting indicator for a high-viscosity-modified asphalt binder, thus indicating its pronounced anti-rutting potential. [Extracted from the article]

The goal of this research was to evaluate some physical properties and mechanical performances of the bituminous concrete during the construction of Boundiali-Madinani road and ensure that they meet the standards set forth in the specifications. Results showed that the grain distribution curve fit into a narrower spindle for the coarse and fine aggregates and flared for the intermediate aggregates. Binder extraction indicated that the average percentage of soluble binder content is 6,01%. Examining Marshall samples showed an average Marshall stability of 1376,55 kg and maximum Marshall flow of 3,80 mm. Also examining Marshall samples demonstrated that the voids in mineral aggregate (VMA) values are between 15 % and 17 %, the voids in the mineral aggregate frame work filled with bitumen (VFB) values oscillate between 73,69 % and 84,42 %. Further, it was shown that the air voids of the mixtures are between 6,07 % and l2,45 %. All test values are consistent with the specifications limits. [ABSTRACT FROM AUTHOR]

Th e review is devoted to the analysis of modern research in the development of formulations and technology for the manufacture of composites based on bituminous binders for the creation of improved asphalt concrete. Methods for modification of bitumen by polymer additives, chemical stabilizers, industrial wastes (recycled polymers, ground tire rubber, fly ash, etc.), nanodispersed additives and carbon nanomaterials to obtain the necessary predetermined properties are considered. Th e positive and negative aspects of using various modifiers are analyzed. Th e efficiency of modification of bituminous binders with recycled polymers and nano(ultra)dispersed fillers is shown, which makes it possible to create composites based on bituminous binders for asphalt concrete pavements with high performance characteristics. The optimal content of additives to the bitumen binder has been analyzed: the amount of thermoplastic polymers and thermoplastic elastomers in the range of 3-10 wt.%, thermosetting polymers − over 10 wt.%, elastomers − up to 15 wt.%, and nano-sized additives: nano-oxides ≥ 5 wt.%, nanoclay ~ 3 wt. %, carbon nanotubes, graphene < 1.2 wt.%. Modification of bitumen with recycled polymers and partial replacement of expensive polymer modifiers with cheaper polymer waste, composite modifiers, namely recycled polymer mixed with ground tire rubber and / or fly ash are considered. Th is allows solving the environmental problems (waste utilization and secondary use) and reduce the cost of asphalt concrete. From the analysis of the experimental results, it becomes clear that for prediction of the properties of modified asphalt concrete, the basic characteristics of the original bitumen, which can differ significantly, are important, as well as the type of modifier (combination of modifiers), its chemical nature, and the efficiency of its dispersing in bitumen. Th e different chemical composition of the initial bitumen and its physicochemical properties probably play a primary role in imparting high and low temperature properties to asphalt concrete. Modification of a bituminous binder with waste polymers and nanofillers, first of all, makes it possible to improve such important performance characteristics of bitumen and asphalt concrete, such as softening temperature, penetration, penetration index, ductility, viscosity, moisture resistance, complex shear modulus, rutting parameter, resistance to cracking, etc. [ABSTRACT FROM AUTHOR]

In this paper we present an algorithm to produce realistic virtual asphalt concretes. The inputs are the geometry of aggregates, and the composition of the asphalt concrete. The outputs are the air voids content and, a 3-dimensional representation of the aggregate skeleton. The air voids that are predicted by the algorithm have been compared to those measured from asphalt made in the laboratory. The key parameters that influence the compaction of an asphalt concrete are the shape of the aggregates, number of aggregates and, volume of mastic, i.e. bitumen, filler, and aggregates smaller than 2 mm. An equation based on a Weibull function, with independent variables the number of aggregates and force required to compact the virtual aggregates, has been developed. This equation can predict the force that the algorithm needs to compact the virtual aggregates to a level equivalent to that reached by a laboratory compactor. [Display omitted] • We present an algorithm to produce realistic virtual asphalt concretes. • The inputs are the geometry of aggregates, and the composition of the asphalt concrete. • The output is the air voids content and the geometry of the aggregate skeleton. • A statistically derived function determines the force that the algorithm applies. • Compaction depends of the number of stones and, the amount of bitumen and dust. [ABSTRACT FROM AUTHOR]

Cigarette butts can be considered as one of the most common contemporary sources of waste, considering the large consumption of cigarettes all over the world. Despite the fact that different solutions have been developed and tested in the recent years aiming to recycle them, cigarette butts are currently landfilled and incinerated. Following the circular economy principles, the experimental application proposed in this paper is an exploratory investigation on the use of shredded cigarette filters as sustainable alternative to the addition of fibers into Stone Mastic Asphalts (SMAs). This represents the preliminary step for a wider research project, aiming to find a possible recycling solution for cigarette butts as fibers in bituminous materials. The use of fibers is a common and well-established solution for the production of high bitumen content mixtures. The fibers have a double function: acting, generally, as a stabilizing agent and, where possible, improving the mechanical performance of the bituminous mixtures. In the present research, two different SMAs were produced and tested aiming to analyze the effects given by the addition of the shredded cigarette filters. The first asphalt concrete, produced with traditional cellulose fibers was taken as a reference mixture, while the experimental mixture was produced with the shredded cigarette filters. The data highlight interesting and promising results for future development, making the use of waste cigarette filters a potential eco-friendly alternative to common cellulose fibers for SMAs. [ABSTRACT FROM AUTHOR]

In the last few years, fibers have been proposed as one of the most important additives for the development of reinforced asphalt mixtures. The optimal fiber selection is a very complex task, as an extensive range of criteria and alternatives have to be taken into account. Decision support systems have been applied in the construction sector, but not for selecting fibers for bituminous mixtures. To fill this gap, two Multi-Criteria Decision-Making Analysis methodologies for the selection of the best fiber to be used in Asphalt Concretes are presented in this paper. The Weighted Aggregate Sum Product Assessment (WASPAS) methodology and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) integrated with Fuzzy Analytic Hierarchy Process (FAHP) are used to evaluate the effect of various types of fibers on the mechanical performance of bituminous mixtures. Given the uncertainty involved, a stochastic simulation is proposed using the Monte Carlo method. A statistical analysis is carried out to verify the results obtained. Both methods of multi-criteria analysis were effective, with TOPSIS being slightly more conservative in the assignment of performance scores. Synthetic fibers proved to be a suitable option as did fibers with high tensile strength and elastic modulus. [ABSTRACT FROM AUTHOR]

In the article bitumen and asphalt concrete qualitative properties depending on using rubber, the crumb is considered. Bituminous binders' comparative physical and mechanical characteristics containing modified crumb are given. It is proved that the increase in the quantity of Kulantau vermiculite leads to a decrease in the thickness of bitumen films on the particle surface. The modification by rubber crumb allows to increase the quality of the bitumen binder, durability of the coatings and to reduce the cost of asphalt coatings, as well as to utilize largetonnage rubber products waste. [ABSTRACT FROM AUTHOR]

The paper concerns the utilization of hydrated lime and zeolites as additives in warm mix asphalt produced with foamed bitumen. The mentioned additives were added to the mixtures in exchange for specific quantities of mineral filler, which amounted to 0.4% and 1.2% of hydrated lime or 0.4% of water-modified and 1.0% of air-dry zeolites in mineral mix. The study investigated warm-produced mixtures with 4.5% and 4.8% binder content and production and compaction temperatures set at 120°C and 100°C respectively. Additionally, reference hot and warm mixtures were evaluated. The testing included: air void content, indirect tensile strength in dry state and after one freeze-thaw cycle as well as the resulting resistance to moisture and frost damage index. The mixtures incorporating hydrated lime and lower bitumen content of 4.5% exhibited increased air voids and mostly unchanged mechanical performance when compared to the reference warm mix. Increased incorporation This has apparently led to decreased results was concluded the production temperature improve the mix' workability and therefore positively affect its mechanical parameters. The paper concerns the utilization of temperatures set at 120°C 100°C air void content, indirect after bitumen content has resulted in significantly improved performance in moisture resistance and compactability which could be compared to that of the reference hot-produced mixture. On the other hand, the incorporation of zeolites in the foamed bitumen mixtures resulted in all cases in increased air void content in the samples. This has apparently led to decreased indirect tensile strength, in both the dry state and after the freeze-thaw cycle. Based on the results it was concluded that the production temperature of the zeolite-bearing mixtures was too low for the zeolite water to significantly improve the mix' workability and therefore positively affect its mechanical parameters. [ABSTRACT FROM AUTHOR]

Moisture damage is a critical problem of asphalt pavements. Some factors affecting the moisture sensitivity of asphalt mixtures include bitumen properties, air void content, and the type of anti-stripping additive. This study investigated the use of nano-silica for improving the properties of different bitumens and to increase the moisture resistance of asphalt mixtures at different traffic loading conditions. Two types of bitumen (60-70 and 85-100 pen grade) were modified with various percentages of nano-silica (0, 0.2, 0.4, 0.7, and 0.9% by the weight of the bitumen), and physical and rheological tests were conducted to determine the optimum nano-content. Then, the optimal content was used to prepare asphalt mixtures at three different air void contents (4, 5, and 6%) to simulate the heavy, medium, and low traffic loading conditions. Indirect tensile strength (ITS) and compressive strength tests were performed on the specimens in dry and wet conditions, and the effect of air void content and the type of bitumen on the moisture sensitivity and compressive strength of unmodified and nano-silica-modified asphalt concrete was investigated. The results showed that nano-silica improved the moisture sensitivity of asphalt mixtures with 60-70 and 85-100 pen grade bitumens at all air void contents and the effect of nano-silica was higher on the moisture sensitivity of asphalt mixtures with 60-70 than 85-100 pen grade bitumen. [ABSTRACT FROM AUTHOR]

For asphalt concrete preparation in laboratory mix-design operations, bitumens are usually mixed with micrometer-sized particles (filler), sand and centimeter-sized crushed stones in a gyratory press at a temperature of about 140–155 °C depending on the bitumen viscosity, until adequate homogenization and compaction take place (air voids optimum). This requires energy consumption. To minimize it, the process needs to be optimized and is usually made empirically. The aim of this manuscript is to gain a comprehension of the physico-chemical mechanisms involved in the process by exploring: (i) the rheological properties (viscosity, activation energy) of a neat and RTFOT-aged bitumen, in presence and in absence of a filler, (ii) the volumetric and resistance behavior under the compaction in a standard Gyratory Compactor (GC) of their blends with aggregates and (iii) the mechanical properties (Indirect Tensile Strength, compression and tensile deformation) of the final products. Correlations between activation energy and pre-exponential factor of the viscosity on a side, and between viscosity, workability and final mechanical properties on the other side allowed to provide a rational interpretation of the physico-chemical processes involved in the framework of the physics of complex fluids. The scientific clues will be of help in optimizing the workability in asphalt concretes productions with obvious repercussions in terms of energy savings, useful for economic and environmental issues. [ABSTRACT FROM AUTHOR]

The mix design of asphalt concrete is usually accomplished in the Iranian ministry of road and transportation according to the Marshall method. Marshall mix design parameters are a function of grading and properties of aggregates, amount and type of bitumen in asphalt mixtures. Therefore, in order to determine these parameters and the optimum bitumen content, many samples with different compounds and conditions must be manufactured and tested in the laboratory, a process that requires considerable time and cost. Accordingly, the necessity of using new and advanced methods for the design and quality control of asphalt mixtures is becoming more and more evident. Therefore, in this study, a genetic programming simulation method was employed to predict the Marshall mix design parameters of asphalt mixtures. Also, multiple linear regression models were adopted as the base model to evaluate the models presented by the genetic programming method. The models proposed here predict the Marshall mix design parameters based on parameters such as the index of aggregate particle shape and texture, the amount and viscosity of the bitumen. The results demonstrated that the proposed methods are more efficient than the costly laboratory method, and genetic programming models with minimal error (identified in this study with RMSE and MAE parameters) and correlation coefficients > 0.9 can predict relatively accurate Marshall mix design parameters. [ABSTRACT FROM AUTHOR]

Asphalt concretes are materials used worldwide. It is well-known that in such materials the minor component, the bitumen, plays the most important role since it binds the high fraction (>95%) of inorganic macrometer-sized particles ensuring a coherent material fit for uses in road pavement. Additives can be used to increase the overall rheological properties, with high benefits in terms of resistance to mechanical stress and to ageing. Among these, nanoparticles have recently been considered as very effective additives in increasing the overall performance, increasing the viscosity, the rutting parameter and the recovery from deformation. However, they are expensive, so a delicate equilibrium between costs and benefits must be found for large-scale uses. In this framework, we furnish our critical analysis of the state-of-the art technologies used for improving the bitumen performances by means of nanoparticles with an eye to eventual added-values (like anti-oxidant effect, antistripping properties, or UV radiation screening which avoids radiation-induced ageing...). We will critically consider the costs involved in their use and we will give our opinion about vanguard techniques which can be fit for the analysis of nanoparticles-containing bitumens and asphalts. Interesting perspectives will be also given for future research and applications. [ABSTRACT FROM AUTHOR]

Copyright of Association of Arab Universities Journal of Engineering Sciences (JAARU) is the property of Association of Arab Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The object of research is the technology of hot asphalt concrete regeneration by the in-place method. Temperature regimes for heating asphalt concrete pavement are one of the key technological parameters that affect the quality of the output regenerated asphalt concrete. In order to establish the dependence of the temperature of the pavement heating at different depths on the heating time, field studies are carried out directly when performing work on the hot regeneration of asphalt concrete using the Reshape method. The work is carried out at an ambient temperature of 25–30 °C and calm weather. The regenerated hot asphalt mix, which is used when conducting studies on the grain composition and bitumen content, corresponded to a hot, fine-grained mixture, dense asphalt concrete, type A, continuous granulometry, grade II, in accordance with DSTU B V.2.7-119:2011. Content of residual bitumen loosened asphalt crumb is 6.0 %. During the research, measurements are carried out at different speeds (1.8 m/min and 2.1 m/min) of the thermal installation for heating the Wirtgen HM 4500 asphalt concrete pavement (country of origin is Germany). The obtained graphical dependencies and mathematical models make it possible to determine that the most optimal pavement heating mode is gradual heating. This mode will allow avoiding the burning of bitumen and provide pavement heating at the level of the base of the regenerated layer, which is very important when determining the temperature of mixing the mixture. Analysis of graphs and mathematical models suggests that a decrease in the temperature of the pavement heating by at least 10–20 °C will lead to an increase in the performance of the thermal device. In this case, the increase in productivity can be from 20 % to 25 %, which will reduce the gas consumption and, accordingly, the cost of work. Thus, the obtained dependencies can be used to optimize the process of hot asphalt concrete regeneration by the in-place method. [ABSTRACT FROM AUTHOR]

Specifications limits and tolerances are crucial in the relationships among contractor, road agency, and citizens because they influence profits, acceptance procedures, and pavement durability. They mainly depend on processes involved, and, unfortunately, their relationship with durability is mainly empirical and calls for further investigation. In the light of these issues, the study described in this paper deals with assessing how durability and pay adjustment (PA) are affected by variations in the main explanatory variables [e.g., air-void content (AV)] within specification limits. A model was set up in order to assess the impact on the modulus of a bituminous mixture, which is a crucial factor for the expected life (EXL). The model was applied to a well-known set of contract specifications in order to check for their suitability and rationale. Results demonstrate that usually, air void–related consequences are worse than penetration-related consequences, which, in turn, outrank aggregate gradation–related and asphalt content–related consequences. An exception is the maximum size of aggregates. Furthermore, when pay adjustments build on empirical algorithms, they have to be layer-specific because the same error implies more severe consequences in deeper layers. Results can benefit both researchers and practitioners. [ABSTRACT FROM AUTHOR]

The article examines the microstructure influence mechanism to mechanical behavior of open graded friction course (OFGC) asphalt mixture. It details the use of digital image processing technology to process the fault images of the specimen and obtain the microstructure parameters of the OGFC asphalt mixture with different gradation. The microstructure influence on mechanical behavior of OGFC asphalt mixture is also explored using the Grey correlation theory.

In this research, the moisture susceptibility of a nanoclay-modified asphalt concrete (AC) mixture containing plastic film (in flakes) collected as urban waste was evaluated with specimens subjected to the tecnico accelerated ageing (TEAGE) procedure. The TEAGE procedure attempts to simulate—in a laboratory setting—the effect of field ageing by applying watering/drying cycles and ultraviolet radiation. For comparison purposes, three AC mixtures were considered, one for control, without plastic and nanoclay, a mixture with only plastic, and a mixture with both plastic and nanoclay. Furthermore, only half of the specimens were subjected to the ageing procedure. The plastic was added to the mixture using the dry process, and the nanoclay was blended with the bitumen before mixture preparation. The moisture susceptibility was evaluated, using a total of 48 Marshall specimens, by the indirect tensile strength ratio (ITSR). From the results of this study, the nanoclay-modified AC mixture containing plastic film presented slightly higher indirect tensile strength (ITS) values, lower moisture susceptibility, and enhanced ageing resistance. These slight improvements can be justified by the reduced air voids content of the samples and consequently they must be seen as conservative. Nevertheless, the modification of AC mixtures with flakes of plastic and nanoclay can be a viable solution for the recycling of plastic film collected as urban waste, being an eco-friendly alternative to disposal in landfills. [ABSTRACT FROM AUTHOR]

Asphalt concrete is highly used to construct pavement layers in the civil engineering field. It is defined as a complex medium composed of aggregates (inclusions), mortar (matrix) and air void. The mortar itself is a mixture of fillers, sand and bitumen. Furthermore, mortar is the phase that links the coarse aggregates. In general, fracture of asphalt concrete occurs within mortar or among aggregatemortar interface. Therefore, two types of fracture can be identified, i.e., adhesive and cohesive damages. The first type is occurred among the interface of aggregate-mortar. The second is taken place within the mortar. This paper presents numerical investigations of the damage initiation and stiffness degradation within the asphalt concrete matrix. Numerical simulations were carried out to investigate, firstly, how damage is initiated and developed, and then, to simulate how cracks can be initiated and propagated within this material. Cohesive finite elements method was adopted to simulate fracture. For adhesive damage, the model was represented by one rectangular aggregate that is linked to the asphalt concrete thanks to a thin layer of the mortar. For cohesive damage, the model was considered as a thick layer of the mortar in between two coarse aggregates. The applied loading was derived from the speed of traffic vehicle. A comparative analysis between four mortars was conducted. The effect of loading and the type of mortar on damage initiation and stiffness degradation will be shown. Moreover, the initiation and propagation of cracks as function of loading and stiffness modulus will be illustrated. [ABSTRACT FROM AUTHOR]

We managed increasing properties of road bitumen and asphalt concrete based on it with help of modification of road bitumen by epoxy compounds based on renewable raw materials, namely by epoxide of rapeseed oil (ERO). Physical-mechanical properties of initial and ERO modified bitumens and asphalts were researched and analyzed. Also was made a comparison of obtained results with similar indexes for trade additives for road bitumen, namely with wax and polymer modifier of SBS type. [ABSTRACT FROM AUTHOR]

Currently, many efforts are undertaken to reach asphalt performance from binder performance in order to reduce costly and time consuming laboratory tests on asphalt materials. In this context, it is important to use and develop appropriate testing methods for a comprehensive binder characterisation, which requires suitable material models. Depending on the application, different models can be used to model rheological bitumen behaviour. This paper focuses on the applicability of the Christensen and Anderson model (CA model) and the Olard-Di Benedetto (2S2P1D) model for bitumen samples containing different amounts of recycled components using various objective functions in the optimisation process. The purpose is to analyse the influence of the reclaimed asphalt rate on the parameters of the investigated models. Dynamic Shear Rheometer tests are conducted on binder samples extracted from Stone Mastic Asphalt mixes with polymer modified bitumen and Asphalt Concrete mixes with paving bitumen, each containing 0–100% reclaimed material components. The resulting influences of the recycled materials are illustrated through master curves, black diagrams and Cole–Cole plots by fitting these experimental data by the application of 2S2P1D and CA model. [ABSTRACT FROM AUTHOR]

Bituminous binders have significant effect on the overall performance of the asphalt mixtures, although binders are not the main component of the asphalt mixture (4-6% by weight). This paper presents an overview of research efforts undertaken to evaluate the sensitivity of asphalt mixture performance to the change of the binder suppliers in the State of Arizona. The binders used in the asphalt mixture have identical Performance Grade (PG). However, the binders were from different suppliers. The laboratory testing program included the dynamic modulus and the repeated load/flow number tests. Asphalt mixtures were collected from four sections on a project constructed in northern Arizona. This project was unique in that all four asphalt concrete mixtures had the same aggregate structure and source but used PG 76-16 binders obtained from four different suppliers. Based on the test results, the tests were sensitive to variations in the properties of the same PG binders obtained from different suppliers. This was also confirmed through statisti cal analysis and comparison with the binder test data. In order to assess the sensitivity of the four asphalt binders on the pavement performance, the binder and mixture data were input into the Mechanistic-Empirical Pavement Design Guide (MEPDG) and design simulations were run to compare rutting and fatigue cracking associated with each of the four PG76-16 binders included in this study. Significant statistical differences in both distress mechanisms were also observed for the different mixtures with changing only the binder supplier. [ABSTRACT FROM AUTHOR]

The present article investigates in laboratory conditions the effect of cyclic freezing and thawing (CFT) on characteristics of the neat bitumen and bitumens modified with different polymers, as well as stone mastic asphalt concretes prepared with the use of the neat and the modified bitumens. Maximal and minimal temperature in cycles of freezing and thawing (FT) is accepted equal to +20 °C and −18 ± 2 °C respectively. Characteristics of low temperature resistance of bitumens (stiffness S and m-value) have been determined on bending beam rheometer at the temperatures of −24 °C, −30 °C, and −36 °C. Strength at direct tension of the stone mastic asphalt concretes has been evaluated in the device TRAVIS (Infratest Ltd., Brackenheim, Germany) at the temperatures of 0 °C, −10 °C, −20 °C, and −30 °C. Resistance of stone mastic asphalt concretes to rutting has been determined on a Hamburg wheel tracking machine. The characteristics of the bitumens have been determined in the initial condition and after 25 and 50 cycles of FT, and the characteristics of stone mastic asphalt concretes, in the initial condition and after 50 cycles of FT. The results obtained experimentally have shown that CFT impacts essentially on the investigated characteristics of bitumens and stone mastic asphalt concretes. Modification with polymers improves the mechanical characteristics of the bitumens and decreases the effect of CFT. It is also found out that when selecting a bitumen for specific climatic conditions it is necessary to take into account both the number of cycles of FT and the characteristic low temperature. [ABSTRACT FROM AUTHOR]

In Nigeria today, polyethylene or water sachet is a major environmental pollutant, a nonbiodegradable material. The usefulness of this pollutant (polyethylene) in the highway industry was investigated by studying its effects on some selected properties of Hot Mix Asphalt, such as, bulk density, stability and flow of the asphalt concrete mix. Specimen preparation was done using Marshall Mix design procedure. The optimum binder content was determined as 5.20% and three samples each for five variations of polyethylene content (2%, 4%, 6%, 8% and 10%) by weight of optimum binder content. It was observed from the study, that the stability and density of asphalt increased with polyethylene content, while a linear reduction in the flow and penetration values was observed with polyethylene content. The optimum modifier content value of 8% by weight of the optimum bitumen content. Models were also developed whose predictive values corroborated well with experimental values with acceptable coefficient of correlation values. Bitumen modified with polyethylene improved the engineering properties of asphalt which therefore means that usage of this waste product in the asphalt production for roadwork is an effective and economical way of managing this waste. [ABSTRACT FROM AUTHOR]

In order to improve the low-temperature cracking resistance and durability of high-modulus asphalt mixture, this article proposes the use of Trinidad Lake Asphalt (TLA) and polyester fibre complex methods to obtain high-modulus asphalt mixture, based on indoor accelerated load, low bending temperature, freeze-thaw splitting and APA fatigue test to study the influence of TLA content on permanent deformation resistance performance, water stability, low-temperature crack resistance and fatigue resistance of high-modulus asphalt mixtures. Meanwhile, it reveals the mechanism of the TLA and polyester fibre composite modified on high-modulus asphalt mixture and recommends the best solution of high-modulus asphalt complex is 30% TLA + 3‰ polyester fibre. [ABSTRACT FROM AUTHOR]

In this study, the effect of using Polypropylene (PP) as an antistripping additive of asphalt mixtures is investigated. Here, the moisture susceptibility of asphalt mixtures is evaluated by determining the micro-mechanisms using the surface free energy (SFE) concept. The adhesion bond between the aggregate and asphalt binder and the cohesion strength of the asphalt binder are considered as the main factors that affect moisture damage of asphalt mixtures. Test results indicate that the use of PP improves the resistance of asphalt mixtures in both wet and dry conditions. Also, the results of the SFE tests showed that the modifying asphalt binder with PP increases free energy of adhesion that will improve adhesion resistance between asphalt binder-aggregates. The amount of debonding energy in the samples which are modified with PP is lower than the control samples. This shows that by modifying asphalt binders, the tendency of asphalt binder-aggregate stripping can be reduced. The results show the total SFE of the asphalt binders of the modified samples have more free energy rather than the control samples. This phenomenon shows that failure in the asphalt binder film and cohesion failure will be happened more rarely. [ABSTRACT FROM AUTHOR]

In order to investigate properties of asphalt mastic containing limestone, pumice and natural zeolite fillers with three penetration grades of asphalt (50/70, 70/100, 100/150) experiments were performed in this study. For this aim, temperature sensitivity and softening point tests were conducted to mastics. The results indicated that the, zeolite has better high-temperature properties and limestone has better low-temperature properties. The results also analyzed by ANOVA statistically using SPSS software, which showed significantly affect the related properties of asphalt mastics. [ABSTRACT FROM AUTHOR]

The red mud waste generated from the alumina refining industry, which remains high alkalinity and problematic pollutants, is occupying considerable land resource and causing significant environmental problems worldwide. Instead of landfills, the utilization of the red mud waste as a substitution of mineral filler in asphalt pavement mixtures has been investigated in this study. The physical and chemical properties of the red mud waste were first characterized. The experimental tests including softening point, penetration, dynamic shear rheometer (DSR) and multiple stress creep recovery (MSCR) were then conducted to evaluate the properties of asphalt mastic. Based on the results on leaching toxicity and radioactivity, the red mud waste had no risk to be used as a building material. Moreover, the addition of red mud waste can improve the stiffness and elasticity of asphalt mastic. The increased rutting parameter and the decreased accumulated creep strain were further found, especially the Sintering RM. In addition, the Sintering RM had the capability to improve the elastic recovery of asphalt mastic, while the Bayer RM had limited contribution to this behavior. Consequently, the red mud waste can be concerned as a secondary resource to replace the natural mineral filler for asphalt pavements. [ABSTRACT FROM AUTHOR]

One of the basic parameters upon which the occurrence of distress in hot mix asphalt depends is the amount of adhesion at the contact surface between asphalt binder and aggregate. Therefore, a number of researches have been conducted throughout the last decade to improve the adhesion between asphalt binder and aggregate using different additives. In the present study, the effects of using nano-TiO2 on the adhesion between the asphalt binder and aggregate are assessed using the surface free energy (SFE) method. The SFE components of the aggregates are determined by universal sorption device test, while SFE components of the asphalt binders are calculated using Wilhelmy plate test. The results of the SFE method indicate that nano-TiO2 increases the wettability of the asphalt binder on the aggregate and promotes the adhesion between the asphalt binder and the aggregate. Furthermore, adding nano-TiO2 leads to the decrease in the acid component of SFE and the increase in the basic component of SFE of the asphalt binder, intensifying the adhesion between the asphalt binder and the aggregate. [ABSTRACT FROM AUTHOR]