► This paper evaluates effects of steel slag on mechanical properties of CIR mixtures. ► Anionic emulsion is more compatible for production of CIR mixtures containing slag. ► Use of anionic emulsion ...improves CIR resistance to permanent deformation. ► Steel slag enhances resistance to permanent deformation of CIR mixtures.
This paper aims to evaluate the effectiveness of steel slag as a substitute for virgin aggregates on mechanical properties of cold mix recycling asphalt pavement. For this purpose, gradation requirements of two types of Reclaimed Asphalt Pavement (RAP) materials in Cold In Place Recycling (CIR) mixes were modified. Mixtures’ gradation requirements were satisfied by adding 20% and 10% of two types of new aggregates in accordance with Asphalt Institute CIR grading requirements. The results showed that the use of steel slag can enhance Marshall stability, resilient modulus, tensile strength, resistance to moisture damage and resistance to permanent deformation of CIR mixes. Use of anionic bitumen emulsion is recommended in preparing mixtures, because of its compatibility with them.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The reason for conducting this research was to examine asphalt mixtures and the influence of additives obtained from recycled Polyethylene Terephthalate (PET) on their mechanical properties. Due to ...this, after the chemical recycling of PET, the substance resulting from the chemical reaction was added to the asphalt binder in different contents. In order to evaluate the mechanical performance of mixtures containing additives, a variety of different mechanical tests were carried out. In order to accomplish this goal, tests including dynamic creep, indirect tensile strength (ITS), and indirect tensile modulus (IDTM) were carried out to determine rutting, moisture susceptibility, and resilient modulus, respectively. The SCB test is used to determine how well a material resists cracking when subjected to low temperatures. The results showed that the addition of an additive derived from recycled PET could increase the rutting resistance, significantly improve resistance against moisture damage and increase cracking resistance at low temperatures. In accordance with the findings of the indirect tensile strength tests, indirect tensile modulus and SCB was the best performance related to the asphalt mixture containing 2% recycled PET. However, this result was different in the dynamic creep test, and the asphalt mixture containing 1% additive showed the best performance. The results of data analysis with one-way analysis of variance showed that all the data obtained in this study are statistically significant considering the confidence factor of 95%, so it can be said that the addition of recycled PET additive has a significant effect on the mechanical properties of the asphalt mixture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The fatigue phenomenon significantly weakens road pavement due to repeated reloading. To enhance fatigue resistance, numerous studies have explored various additives in asphalt mixtures. This review ...focuses on key variables influencing the effectiveness of additives, including fibers, polymers, nanomaterials, waste materials, and biomaterials, in improving the fatigue performance of asphalt mixtures. The study initially identifies different additives and fatigue testing methods used for asphalt mixtures. It evaluates the impact of factors such as modifier content and size, base asphalt binder type, mixing processes, dispersion behavior, and testing conditions on the fatigue behavior of modified asphalt mixtures. The cost-effectiveness and environmental impact of additive application have also been assessed. Additionally, research gaps and future prospects for modified asphalt mixes are outlined. Existing studies demonstrate the benefits of additives like basalt fiber, polyester fiber, styrene–butadiene–styrene (SBS), nanosilica, crumb rubber, and biooils in enhancing the fatigue life of pavement constructions. However, challenges exist in the application of modifiers due to limited practical implications and insufficient knowledge. Further research is needed on factors such as additives’ dispersity, compatibility, aging resistance, economic viability, and modifying mechanisms in morphological and micromechanical aspects to enhance the fatigue performance of the modified asphalt mixture.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Studies show that warm mix asphalt (WMA) technology is a practical solution against the high production temperature of rubberized-asphalt (RA) mixtures. RA mixture containing WMA additive is ...considered as an eco-friendly technology contributing to noise reduction and performance optimization of asphalt mixtures. This study aims to introduce two organic WMA additives called slack wax (SW) and polypropylene wax (PPW) which are used to lower the production temperatures by reducing the viscosity of RA mixtures. Rotational viscosity (RV) as a common bitumen test (Equiviscous, ZSV, and S-ZSV methods), as well as tests related to mixtures including resilient modulus (
M
r
) and moisture susceptibility (TSR and MRR methods), were carried out on binder and mixture specimens. According to the results, 6% (by the binder’s weight) of both WMA additives reduced the mixing and compaction temperatures of the RA binder by about 20–25 °C. Also, CRM and both WMA additives improved the stiffness of mixtures by increasing the resilient modulus (
M
r
). In terms of moisture susceptibility, although nearly all specimens could pass the minimum requirement of SCDOT, both WMA additives and CRM caused a reduction in ITS value of wet mixtures and final TSR value. MRR test results followed a similar trend, though resilient modulus was more sensitive to moisture damage compared to ITS. The results suggest that PPW and SW are suitable and cost-effective warm additives that can be used in combination with CRM in areas with hot climates and low precipitation. Nevertheless, additional experiments should be done to further validate the performance of CRM mixtures with these two warm additives.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Rutting is one of the most common distresses in flexible pavements and can affect vehicle controlling features. Although asphalt binder constitutes a small percentage of the asphalt mixture, its ...properties play a crucial role in pavement performance and its rutting resistance. One way of improving binder properties and rutting resistance is to use additives. In this research, nanoclay and SBR polymer have been simultaneously used to modify 60–70 penetration binder to study rutting resistance of binder and asphalt mixture. To this end, the storage stability, rotational viscosity, DSR, and RCR tests on binder and marshal stability were performed, and dynamic creep and wheel track tests on asphalt mix were performed to assess rutting performance. The test and statistical analysis results indicated that nanoclay has considerably positive impact on rutting and elastic deformation of neat and SBR-modified asphalt binder and mixture.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Properties of asphalt mixture play a vital role in structural integrity and performance of flexible pavements structure. In flexible pavements, asphalt concrete surface layer consists of asphalt ...binder, aggregates and in some cases additives. In this research study styrene butadiene rubber (SBR) and recycled polyethylene terephthalate (rPET) are used to evaluate their individual and also their combinational effects on moisture susceptibly, rutting and low temperature cracking of asphalt concrete mixture. Combinations of SBR, rPET and water were vulcanized to form thermoplastic elastomer polymers as bitumen modifier. Then conventional bitumen tests including penetration grade, softening point and rotational viscosity (RV) as well as asphalt mixture tests including resilient modulus, dynamic creep, IDT fatigue and moisture susceptibility tests were performed on binders and asphalt mixture specimens. The test results indicated that SBR and rPET increase viscosity and softening point and stiffen the binders by reducing their penetration grade. Test results of specimens prepared with modified binders showed higher tensile strength and higher rutting resistance than that of control specimen. Within the content of this study it is concluded that modification of bitumen with SBR reduces low temperature stiffness of binder and hence reduces failure due to thermal cracking and modification with rPET increases rutting resistance of the mixture at high temperatures.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The aim of the current research was to develop models to predict the severity of accidents on rural roads in Tehran province, Iran. In this regard, using accident data from 2017 to 2020, the machine ...learning algorithms, including multiple logistic regression, multilayer perceptron neural network (MLPNN), and radial basis function neural network (RBFNN) models, as well as statistical methods, including Kolmogorov–Smirnov test, Friedman test, and factor analysis, were implemented to determine the contributory factors in the severity of accidents. Thus, nine variables affecting the severity of accidents were considered in modeling, and then the effect of each variable was calculated. By comparing the results of artificial neural network (ANN) models and the Friedman test, it was indicated that the human factor had a remarkable effect on accident severity. In addition, both machine learning and statistical methods can be served as guidance for safety authorities to provide safety solutions, thereby leading to reducing accidents. Finally, the performances of ANN models were analyzed by other mathematical models built by MATLAB programming.
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CEKLJ, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The study described in this paper focused on the possible use of waste products coming from the production of styrene–butadiene rubber (SBR) and polybutadiene rubber (PBR), as bitumen modifiers. ...Modified binders containing these products were prepared in the laboratory with different polymer dosages and were thereafter subjected to the evaluation of empirical and rheological properties. For comparative purposes, the study also considered SBR and PBR products of premium quality. Ageing effects were also taken into account by means of proper laboratory simulations. Obtained results indicated that the two types of polymer (SBR and PBR) have completely different effects on the rheology and expected performance of the resulting modified binders. In particular, while the two polymers showed similar effects in terms of resistance to permanent deformation, the SBR products proved to be superior from the viewpoint of fatigue resistance. However, only minor differences were found when comparing the effects produced by premium quality and waste polymers. As a result of the experimental findings, it was concluded that the use of waste SBR polymers can be an attractive solution for the production of affordable modified binders.
This study assesses the relationship that existed between various variables and their subvariables on rural roads in Qom, Iran, using statistical analysis and calculates the relationship between the ...considered factors and accident severity. A logit model was applied to determine the factors affecting the severity of accidents. In addition, two artificial neural network (ANN) models were developed using two kinds of learning methods to train neurons to select the best result. The results of modeling and analysis of accidents using various techniques revealed that each technique, depending on its purpose, examined the severity of accidents from a different point of view and represented various outcomes. Finally, the performance of the proposed models was validated utilizing other mathematical models. As a result, putting the output results together, the best measures can be suggested to increase the safety of people on rural roads. The outcomes of this study may aid these service providers in strategic planning and policy framework.
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CEKLJ, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The main objective of this research is to investigate the rutting of modified mixtures with two additives of crumb rubber and polyethylene terephthalate (PET).Therefore, ITS method, resilient modulus ...and Dynamic creep were used to investigate asphalt behaviour with these two additives in this article. Modified blends include ten blends that are made by combining crumb rubber and polyethylene terephthalate in various percentages. The modifiers are combined in two percent 10% and 15% with 60/70 penetration bitumen. Finally, with these mentioned tests, the results of the ten modified samples along with the non-modified one were compared. The results showed that the addition of polyethylene terephthalate increased the viscosity and reduced the density; therefore, addition of more polyethylene terephthalate in the modifier reduces the flow number and, on the other hand, addition of 15% modifier containing polyethylene terephthalate resilient module increases the flow number by about 66%. Ultimately, neural network method was used to predict the result of dynamic creep test; indirect tensile strength and the capability of neural network method have been measured to estimate the laboratory result. According to the results, ANFIS can estimate the laboratory data correctly.
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