Properties Of Asphalt Concrete Research Articles

ВИКОРИСТАННЯ ГУМОВОЇ КРИХТИ ДЛЯ МОДИФІКАЦІЇ БІТУМУ

The main reason for the destruction of road wear layers is the loss of structural connections in the material of asphalt concrete layers, which is largely due to the low quality of bitumen. In order to improve the properties of binding materials, composite binders based on bitumen and modifiers are used in foreign and domestic practice for the installation and repair of road surfaces. One of the ways to improve the properties of asphalt concrete is the use of modifiers based on rubber crumb obtained from car tires that have lost consumer properties, as well as other rubber products. The problem of using tires is also of great environmental importance. Used products accumulate in places of operation (car parks, airfields, industrial enterprises, etc.). In addition, tires have a high fire hazard, and products of uncontrolled combustion have an almost irreversible impact on the environment. The paper presents a domestic and foreign analysis of the use of rubber crumb to modify bitumen in order to improve the physical and mechanical indicators of road wear. Asphalt concrete coating on transport facilities, which includes bitumen, is subject to significant influence of adverse factors (precipitation, change in environmental temperature, load from motor vehicles, etc.), which reduce its durability. Modification of road bitumen is one of the promising ways of increasing the durability of asphalt concrete pavement on artificial structures. Since the rubber crumb has an organic affinity with the components of bitumen and the physical and mechanical interaction gives a homogeneous material with significantly different characteristics from the original material.

ПЕРЕДУМОВИ ЗНЯТТЯ ОБМЕЖЕНЬ ДО РУХУ ВАНТАЖНИХ ТРАНСПОРТНИХ ЗАСОБІВ ЗА ВИСОКОЇ ТЕМПЕРАТУРИ ПОВІТРЯ

Introduction. Currently, in Ukraine, there are restrictions on the traffic of vehicles with an actual weight of more than 24 tons and an axle loading of 7 tons during the day at an air temperature above 28 °C, except for vehicles carrying dangerous, perishable goods, live animals and poultry, and as well as transportation related to the prevention or liquidation of the consequences of emergency situations. An air temperature of 28 °C is considered to be the temperature at which the road pavement structure under the influence of dynamic loadings can sharply lose its load-bearing capacity, which is one of the conditions under which a threat to traffic safety is created or roads can be damaged and destroyed. Problem statement. The analysis of the regulatory documentation showed that during designing of pavement structure, the climatic conditions of asphalt concrete performance should be taken into account and pavement must withstand the accumulation of plastic strains in summer, which requires measures to ensure its rutting resistance. At the same time, the algorithm for ensuring rut stability does not exist yet. It is quite likely that this issue can be resolved by performing appropriate research work and implementing harmonized European standards, respectively, by amending the building codes, etc. However, the question arises whether we do not perform the requirements of the regulatory documentation and design the pavement structure without considering the climatic conditions and ensuring the rut resistance of asphalt pavement, or still comply with these requirements, which should be clarified. Objective. Development of criteria for analyzing the performance conditions of asphalt concrete in the pavement structure and ensuring its rutting resistance during operation. Materials and methods. Prerequisites for the establishment of restrictions on the movement of freight vehicles at air temperatures above 28 ° C, analysis of operating conditions of asphalt concrete in the construction of pavement. Results. According to the results of the work, the influence of temperature, bitumen properties and loading time on the change of asphalt concrete properties has been established. Criteria for the analysis of climatic conditions of asphalt concrete have been developed and criteria for taking into account operating conditions have been established. Approximate bitumen grades for ensuring the asphalt concrete rutting resistance have been established on the basis of establishing the relationship between the standard properties of bitumen and operating properties. Conclusions. For evaluation of possible rut formation resistance of asphalt concrete, it is needed to perform an analysis by the bitumen grade in its composition, the total number of passes of vehicles with estimated loadings during the pavement operational term, the category of road, the type of asphalt concrete, the speed of traffic, as well as the year of pavement arrangement. In order to ensure the rut resistance of asphalt concrete, it is advisable to use the established criteria in the future during the pavement design.

Modeling the Thermal Behavior of the Viscoelastic Properties of Asphalt Concrete

The viscoelastic properties of asphalt concrete are susceptible to the variation in the pavement temperature. In the present work, asphalt concrete beam specimens were prepared at optimum binder content and tested under repeated flexural stresses for fatigue life. Three testing temperature were implemented (5, 20, and 30) ℃. The variation in the phase angle, dissipated energy, flexural stiffness, and permanent deformation due to the testing temperatures were monitored and modeled. It was concluded that the viscoelastic properties of asphalt concrete are highly sensitive to the variation in testing temperature. The phase angle and the permanent deformation increases sharply as the testing temperature rises. However, the dissipated energy and the flexural stiffness declines as the testing temperature rise. Mathematical models were obtained which can be implemented in identifying the thermal behavior of the viscoelastic properties of asphalt concrete.

Effect of Recycled Aggregate Modification on the Properties of Permeable Asphalt Concrete

This study aims to evaluate the pavement performance of permeable asphalt concrete (PAC) produced with modified recycled coarse aggregate (RCA) based on six types of single modification methods and three types of double modification methods. Firstly, the water absorption, apparent density, and crushing value of the RCA before and after modification were tested. Subsequently, the performance of PAC with these types of modified RCA was investigated, including the optimum asphalt-aggregate ratio, water stability, high-temperature performance, and low-temperature crack. The test results show that the physical properties of RCA were improved to some extent owing to the modification methods adopted, except that the water absorption of RCA-C and RCA-PC increased by 33.5% and 32.6%, respectively, compared with that of RCA. This increase in the water absorption was attributed to the high water absorption of the cement mortar. As a whole, various modification methods have different effects on the road performance of asphalt mixtures, and soaking RCA with slag powder and silane coupling agent was prominent among them. Compared with the PAC with RCA, the Marshall stability, Marshall stability of immersion, residual stability, TSR, dynamic stability and low-temperature tensile strength of PAC with RCA-SLSC were increased by 31.8%, 41.0%, 7.0%, 5.8%, 280.7% and 17.2%, respectively.

Self-Healing Properties of Asphalt Concrete with Calcium Alginate Capsules Containing Different Healing Agents.

Calcium alginate capsules encapsulating rejuvenator are a promising self-healing technology for asphalt pavement, but the effects of different healing agents on the self-healing performance of asphalt concrete has not been considered. In view of this, this paper aimed at exploring the effects of calcium alginate capsules containing different healing agents on the self-healing properties of asphalt concrete. Three types of capsules with sunflower oil, waste cooking oil and commercial rejuvenator were fabricated via the orifice-coagulation bath method and the interior structure, mechanical strength, thermal stability and oil content of the prepared capsules were characterized. The healing levels of asphalt mixtures with different capsules under different loading cycles and stress levels were evaluated. Furthermore, the saturates, aromatics, resins and asphaltenes (SARA) fractions and rheological property of extracted asphalt binder within test beams with different capsules after different loading conditions were assessed. The results indicated that all the three types of capsules meet the mechanical and thermal requirement of mixing and compaction of asphalt mixtures. The healing levels of test beams containing vegetable oil capsules were higher than that of waste cooking oil capsules and industrial rejuvenator capsules. The strength recovery ratio and fracture energy recovery ratio of test beams with vegetable oil capsules reached 82.8% and 96.6%, respectively, after 20,000 cycles of compressive loading at 1.4 MPa. The fracture energy recovery ratio of the waste cooking oil capsules also reached as high as 90%, indicating that waste cooking oil can be used as the healing agent of calcium alginate capsules to improve the self-healing property of asphalt mixture. This work provides a significant guide for the selection of healing agent for self-healing capsules in the future.

Development of a method for improving the quality of the road surface with the addition of asphalt granulate

The quality of the road surface is a fundamental criterion during the operation of the roadway. The article considers the issue of wear of the top layer of asphalt concrete coating from the wheels of vehicles during operation. The causes of premature destruction of the road surface have been determined. The physical and mechanical properties of asphalt concrete are presented as strength and deformation indicators. The goal is to increase the strength characteristics of road surfaces made of hot asphalt concrete mixtures, taking into account the use of the previous asphalt granulate in the formation of the upper layer of the roadway. To achieve this goal, the authors consider the factors affecting the change in strength and deformation characteristics in heavy traffic. The relevance of this direction lies in the development of public roads and is implemented within the framework of the national project Safe and high-quality highways. The established operational period of asphalt concrete is ensured by the correct choice of components and components for the formation of a high-quality mixture. The authors of the article consider the possibility of forming a road surface with specified characteristics by regulating the properties of asphalt concrete and its structure using crushed asphalt granulate in the technological process. The dependences of the strength of the dispersed system on the fractional size of the asphalt granulate are presented. The use of granulate in the fractional composition of two standard sizes in a ratio of 50 % to 50 % improves the strength and deformation properties of the roadway, increases the adhesion of the binder and the water resistance of the asphalt concrete coating. According to the results of experimental studies, the technological sequence of the mixture formation with the use of asphalt granulate, as well as its fractional and volumetric composition in the total volume of the mixture is proposed.

Direct tensile test evaluation and characterization for mechanical and rheological properties of polymer modified hot mix asphalt concrete

AbstractUsing polymer to modify asphalt binder for better performance has become popular in pavement engineering, for which to evaluate the effect of polymer addition on the properties of the asphalt concrete is essential for mix design. Conventional mechanical test methods, primarily using bending of beams and indirect splitting, are not only materially and timely costly and labor intensive but also provide no direct information for the viscoelastic and rheological characteristics of the materials. This paper reports a study using direct tensile test (DTT) to evaluate the effect of polymer on both mechanical and rheological properties of modified asphalt concrete. Two types of polymers, which are styrene‐butadiene‐styrene (SBS), and a mixture of SBS and polyvinyl chloride (PVC), were investigated on two mixes using fine and coarse aggregates, respectively. It has been found that SBS generates improvement for both mechanical and rheological properties of hot mix asphalt concrete. However, using a hybrid mixture of SBS and PVC shows that PVC can further improve the mechanical properties, but deteriorate the toughness of the asphalt concrete. At the end, a simple quadric polynomial model has been proposed to characterize the combined SBS and PVC effects for the sake of the guidance for mix design.

Effect of 3D aggregate shape on thermo-mechanical properties of asphalt concrete using a mesostructure-based homogenisation method

ABSTRACT Morphological characteristics of aggregates have long been recognised as an essential factor influencing the thermo-mechanical behaviour of asphalt concrete. However, studies on accurate quantification of this influence are still very limited. For this reason, the present study developed a mesoscale finite element method to investigate the effects of three-dimensional (3D) aggregate shape on the complex modulus, thermal expansion coefficient, thermal conductivity, and mesoscale responses of asphalt concrete. An upscaling homogenisation method was adopted to predict the effective thermo-mechanical properties of asphalt concrete. The 3D true sphericity (3DTS) was used as an index to characterise the aggregate shape. The computational results showed that the temperature and loading frequency significantly affect the role of aggregate shapes in determining the effective dynamic modulus of asphalt concrete. The high-angularity aggregates can increase the deformation resistance of asphalt concrete under thermal load, and thus reduces the thermal contraction coefficient of asphalt concrete. However, aggregate shape has no significant effect on the thermal conductivity of the asphalt concrete. In addition, the asphalt concretes with less angular aggregates have stronger low-temperature damage resistance, while the aggregates with high angularity can improve the rutting resistance of asphalt pavements.

Sensitivity of Viscoelastic Properties of Asphalt Concrete to the Variation in Binder Content

Sensitivity of Viscoelastic Properties of Asphalt Concrete to the Variation in Binder Content

The comparative study on the performance of bamboo fiber and sugarcane bagasse fiber as modifiers in asphalt concrete production

Highway pavement structures are expected to be adequately strong and durable for their design life which can be achieved only when the pavements are properly designed, constructed, maintained, and managed. In Ethiopia, most of the asphalt pavement is suffering from fatigue, creep, and rutting in long term. These stresses may be occurred due to the shortage in the mechanistic properties of either the binder or the asphalt mixtures as well as due to the increase in traffic loads. Failures of some roads can be attributed to the poor design of the asphalt mixes and materials being used. The properties and dosage of additive materials in hot mix asphalt affect the overall performance of pavement structure. Hence, modifying the properties of asphalt is necessary to enhance the performance of HMA. This study aims to investigate the performance of bamboo fiber and sugarcane bagasse fiber on the mechanical properties of Hot Mix Asphalt production. This research was conducted by using an experimental research design method and Non-Probability sampling techniques were adopted to collect samples. A sample preparation method of asphalt mixture specimens for asphalt mix design was performed based on AASHTO, ASTM and EN Standard specifications. The tests required were aggregate tests, a Bitumen test, Marshall test, and performance tests such Indirect Tensile Strength test and Rutting Test (RT) were conducted to evaluate a comparative study on the performance of bamboo fiber and sugarcane bagasse fiber as a modified Hot Mix Asphalt production. The preparing HMA mixes using crushed stone coarse aggregate, Fine aggregate, Mineral fillers 60/70 Bitumen, and by using bamboo and sugar cane bagasse fiber as additives were used to compare the results at a varying bitumen content of 4.5,5,5.5,6% bitumen. The Asphalt additives were used in the range from 0.2% to 0.5% of the total weight of the sample. Then, finally, the results of the laboratory were compared to standards of specifications. The optimum both fibers content obtained at 0.3% and OAC & OMF (5.2% & 4%) respectively, suggests that using both BF & SCBF fibers in asphalt concrete mixture improves the performance of asphalt pavements to resist external loads. Both fibers at 0.3% content better modify asphalt marshal stability, ITS of HMA, and Rutting resistance of AC. Finally, based on this study it was proved that the performance and properties of Asphalt concrete are affected by Fiber type and its content.

Investigation of using conductive asphalt concrete with carbon fiber additives in intelligent anti-icing systems

ABSTRACT In winter, ice on the roads causes traffic accidents and congestion. In recent years, various techniques have been developed to provide more effective, efficient, and environmentally friendly solutions to the problem of road icing. One of these is electrically conductive asphalt concrete (CAC). This study aims to develop an intelligent anti-icing system by increasing the conductivity and mechanical properties of asphalt concrete. Two different conductive asphalt series were produced. Series 1 uses a binder modified with 3% styrene butadiene styrene (SBS) block copolymer and Series 2 uses a binder modified with both 3% SBS and 14% carbon black (CB). In both series, 0.3% carbon fiber (CF) by weight was added to the dry mixture. Thermal dissipation status, ice melting performance, freezing, and electrical conductivity heating cycle tests were conducted. The long-term mechanical and conductivity performances of CAC specimens were assessed with pre-and post-cycle experiments. CAC, developed for its conductivity and mechanical properties, was integrated with the intelligent anti-icing system. A comparative cost analysis was also performed to assess conventional asphalt concrete and the CAC. The binder phase was found to contribute to the mixture conductivity. Such systems can be integrated with Intelligent Transportation Systems (ITS).

Effects of different aggregate and conductive components on the electrically conductive asphalt concrete's properties

ABSTRACT Since ancient times, the closure of roads due to ice and snow accumulation is one of the most critical problems of highway transportation. There are two different approaches to prevent icing on the road: passive and active methods. In this study, the most efficient aggregate type and the asphalt mixture combination containing electrically conductive components was determined for electrically conductive asphalt pavements which are considered among the active anti-icing methods. For this purpose, a two-stage experimental study was carried out. In the first stage, asphalt concrete (CAC) specimens with 25 different aggregate and conductive component contents were produced and their properties such as volumetric resistivity, the temperature variations under constant (30 Volt) electrical direct current (DC), heating and cooling times and thermal conductivity were determined. Marshall asphalt design was also performed for three series (2.1; 4.1, and 4.3) for the best electrical and thermal conductivity properties in the second stage of the study. Volumetric resistivity tests were performed and temperature variations under constant voltage (30 V) were determined on the Marshall specimens. As a result of the study, environmentally friendly asphalt specimens with wearing layer having high electrical conductivity properties were developed. It was concluded that not only the conductive components but also the aggregate type was reasonably effective in terms of anti-icing performance and CAC specimens could exhibit behaviour close to traditional asphalt properties.

ВИБІР БІТУМУ ДЛЯ ВИРОБНИЦТВА АСФАЛЬТОБЕТОННИХ СУМІШЕЙ З УРАХУВАННЯМ ЕКСПЛУАТАЦІЙНИХ УМОВ

Abstract Introduction. Asphalt concrete is the most common material for paving layers of roads. Significant advantages of asphalt concrete include high operational characteristics, relatively high technical values, suitability for regeneration and more. At the same time, asphalt concrete has its drawbacks, one of which is the significant dependence of strength and deformation characteristics fronm the ambient temperature. The essential role in the temperature properties of asphalt concrete is played by bitumen, the quality of which is currently evaluated by standard indicators in accordance with the penetration system. The properties of bitumen can be more accurately and objectively evaluated by rheological indicators (viscosity and cohesion) or by operational ones, which are determined depending on the climatic conditions of asphalt concrete layers. Therefore, there is a need to analyze the climatic conditions of asphalt concrete in the pavement structure. Problem statement. Today in Ukraine a penetration system uses for evaluation of bitumen properties that determines the type of bitumen and the corresponding characteristics. About 30 years ago, the United States developed a system for evaluation of bitumen operational characteristics, which combines climatic conditions and transport loadings. This approach allows to choose bitumen for assigned designing combination of high and low temperatures. Evaluation of the appropriate climatic conditions of asphalt concrete in Ukraine will allow to develop zoning on the basis of which it is possible to make the optimal choice of bitumen, which would increase the durability of asphalt concrete and pavement structure in general. Purpose. Creation of bitumen selection system during designing of pavement structure, considering the ambient temperature, transport loadings, traffic intensity, level of reliability and location of asphalt concrete in the pavement structure. Materials and methods. Collection of climatic data regarding ambient temperature according to the data of meteorological stations located in regional centers of Ukraine for the period from 2005 till 2020 and determination of the needed operational properties of bitumen. Results. The zoning of the territory of Ukraine according to the climatic conditions of asphalt concrete considering the ambient temperature, transport loadings, traffic intensity, level of reliability and location of asphalt concrete in the pavement structure is developed. Conclusions. Development and introduction of zoning of the territory of Ukraine according to the operational conditions of asphalt concrete and bitumen selection system according to operational indicators will prevent the formation of destruction in the form of plastic deformations, cracks and low-temperature cracks and thus will increase the durability of asphalt concrete. Keywords: asphalt concrete, bitumen, binding layer, operational properties, pavement structure, pavement layer, upper layer of foundation.

Thermo-piezo-rheological characterization of asphalt concrete

The linear viscoelastic (LVE) properties of asphalt concrete is investigated in this paper using a controlled-strain triaxial dynamic modulus test over wide frequency, temperature, and confining pressure ranges. The time–temperature-pressure superposition principle (TTPSP) is applied to validate the thermo-piezo-rheological simplicity of the tested materials using triaxial master curves. The LVE response is found highly stress-dependent at intermediate and high temperatures. The Prony series modeling of time-domain properties ascertains that confining pressure strongly correlates with long-term relaxation modulus, the absolute maximum slope of the relaxation modulus, and viscoelastic damage parameter. The stress triaxiality ratio concept is applied, and a new shift model is proposed that takes the triaxiality ratio as an internal state variable in the TTPSP. The model prediction agrees well with the experimental data. Moreover, a relationship between the long-term relaxation modulus and the triaxiality ratio is established. The triaxiality ratio coupled with TTPSP can accurately describe the stress-dependent response of asphalt concrete in the LVE domain.

Effect of Ageing on Self-Healing Properties of Asphalt Concrete Containing Calcium Alginate/Attapulgite Composite Capsules.

Calcium alginate capsules within asphalt concrete can gradually release interior asphalt rejuvenator under cyclic loading to repair micro cracks and rejuvenate aged asphalt in-situ. However, asphalt pavement will become aged due to environmental and traffic factors during the service period. In view of this, this paper investigated the effect of ageing on the healing properties of asphalt concrete containing calcium alginate/attapulgite composite capsules under cyclic loading. The capsules were fabricated using the orifice-bath method and the morphological structure, mechanical strength, thermal stability, oil release ratios and healing levels of capsules in fresh, short-term ageing and long-term ageing asphalt concrete were explored. The results indicated that the different ageing treatments would not damage the multi-chamber structure nor decrease the mechanical strength of capsules but would induce the capsules release oil prematurely. The premature oil released from capsules in turn can offset the ageing effect owing to ageing treatment. The short-term ageing and long-term ageing plain asphalt mixtures gained strength recovery ratios of 39.3% and 34.2% after 64,000 cycles of compression loading, while the strength recovery ratios of short-term ageing and long-term ageing asphalt mixtures containing capsules were 63.5% and 54.8%, respectively.

Evaluation of the Strength Properties of Asphalt Concrete using Natural Fibres as Reinforcing Additives

The period of maintenance and rehabilitation of asphalt concrete pavement can be increased by using fibres as reinforcement in a bituminous mix. Shredded Sisal fibre (Agave sisalana) and Sponge gourd (Luffa cylindrical) were used as reinforcements in bituminous mix. The fibres were added to hot mix asphalt in varying proportion of 0.1%, 0.2%, 0.3%, 0.4% and 0.5% by weight. The strength of fibre reinforced asphalt concrete was determined by conducting Marshall stability test. The tensile strength on 40 strands of fibre gave 167.43 N/mm2 and 24.58 N/mm2 for Sisal fibre and sponge gourd fibre respectively. Marshall Stability test results indicated that Sisal fibre gave minimum and maximum values of 4.46 kN and 5.54 kN, respectively, which exceeded the 3.5 kN minimum stability value for wearing course in the Nigerian General Specification for Roads and Bridges. The flow values obtained showed that the flow values are more than the 4 mm minimum value except for 0.1 sisal fibre dosage which has a value of 3.99 mm. The high flow values obtained was an indication of the reinforcing effects of the fibres which made the asphalt concrete stronger and hence have great resistance to plastic deformation.

Performance Evaluation of Asphalt Concrete Using Waste Blister Pack As Additive

Disposal of that large amount of wastes especially non-decaying waste materials become a problem of great concern in developed as well as in developing countries. Recycling waste into useful products is considered to be one of the most sustainable solutions for this problem. Among blister packs is one of them which are being produced in the large amount over the world. In this study waste, blister pack was used in asphalt concrete as an additive to enhance the properties of asphalt concrete. For this purpose, four different serial asphalt concrete samples were produced using shredded waste blister pack in different proportions (0%, 0.25%, 0.50%, and 0.75% by weight of total aggregate and five different percentages of asphalt (4.5%, 5.0%, 5.5%, 6.0% and 6.5% by weight of total aggregate). It has been found that using 0.5% additive has given more satisfactory results than others and also showed the highest stability. It was also observed that the optimum asphalt content has been decreased when increasing the percentage of the waste blister pack.

Study of crushed stone-mastic asphalt concrete using fiber from fly ash of thermal power plants

Enhancing the quality, improving the compositions and technology of crushed stone-mastic asphalt concrete are among the urgent problems in Ukraine. The feasibility to use modifying additives in the compositions of asphalt concrete mixtures to improve the quality of crushed stone-mastic asphalt has been defined. For the first time in Ukraine, laboratory studies were carried out on the use of fiber from fly ash from thermal power plants to reinforce hot asphalt concrete mixtures for the construction of road and airfield pavements. The features of the surface topography of the fiber under consideration, the properties of the asphalt binder are investigated, and its bitumen-holding capacity is assessed. The rheological properties of the material are determined. The influence of various powder stabilizers on the structure formation of crushed stone-mastic asphalt concrete mixtures and the properties of crushed stone-mastic asphalt concrete has been established, and fiber from fly ash from thermal power plants has been substantiated to be the most effective reinforcing additive, the most effective modifier, and has shown advantages over traditional additives.

Effectiveness Evaluation of Shredded Waste Expanded Polystyrene on the Properties of Binder and Asphalt Concrete

The disposal of massive amounts of waste, particularly nondecaying waste, is now a major issue for both developed and developing countries. One of the most sustainable solutions to this problem is to recycle garbage into valuable items. Expanded polystyrene, which is manufactured in large quantities, is one of these waste materials. This is being used globally as packaging material, construction material, and household appliances. The waste expanded polystyrene (EPS) is necessary due to its biodegradability, and aesthetically, it has a great negative impact on the environment. The goal of this research would be to see how shredded waste EPS affects the characteristics of asphalt and asphalt concrete. For this, four separate serial asphalt concrete samples were made with varying amounts of shredded expanded polystyrene waste (0.25, 0.50, 0.75, and 1% by the weight of the total aggregate) and five different percentages of asphalt (4.0, 4.5, 5.0, 5.5, and 6.0% by the weight of the total aggregate). In this study, 60/70 grade bitumen was used. Modified asphalt concrete properties were examined and compared with those of the standard specimens. The penetration, ductility, softening point, flash point, and fire point of the asphalt will all be affected by the addition of EPS plastic waste. The optimal asphalt content of the conventional specimen was 5.1 percent, and different percentages of EPS with OAC were applied. The mechanical properties of all specimens were studied in terms of Marshall properties after Marshall specimens were created with regard to OAC by adding EPS. It has been discovered that applying a 0.5% addition produces improved results than other methods. Simultaneously, as the EPS percentage increased, the stability value increased by approximately 82.61% compared to the traditional mix.

Preparation and electrical properties of conductive asphalt concretes containing graphene and carbon fibers

Graphene is a promising material applied in the field of road. In this study, graphene and carbon fiber were added in the asphalt concretes to achieve the aim of the effect of electrical conductivity and thermal conductivity. Graphene played a complementary role in the overall conduction pathway. The distribution of graphene in asphalt could be observed by fluorescence microscope. Meanwhile, preparing the conductive asphalt mastic and mixing method of the conductive asphalt concrete were also investigated. DSR test was used to test the effect of graphene on the shear deformation resistance and creep performance of bitumen. CT images were introduced into finite element program for analyzing current density distribution of conductive asphalt concrete to obtain the appropriate gradation. The optimum content of conductive medium was determined by measuring resistivity of concrete and heat conduction coefficient. Pressure sensitive characteristics were also researched to evaluate the effect of stress on electrical conductivity. Based on the results, it was found that addition of graphene reduces the resistivity of concrete and improves the thermal conductivity.