Hot Asphalt Mixtures Research Articles

Analysis of the grouting fullness and road performance of hot-recycled semi-flexible pavement materials

In order to enhance the utilization efficiency of reclaimed asphalt pavement (RAP) and contribute to sustainable waste management, the implementation of hot recycling technique is employed to produce semi-flexible pavement materials. This research endeavor aims to scrutinize the performance characteristics of semi-flexible pavement materials manufactured through hot recycling. To attain this objective, the grout construction issue is simulated with the aid of ABAQUS software, enabling a comprehensive investigation into the impact of various load positions, surface areas, and grout heights on the horizontal and bending features of the pavement. The findings of the study indicate that the judicious incorporation of reclaimed asphalt pavement (RAP) into the hot recycled asphalt mixture as a semi-flexible pavement material exhibits an acceptable grouting rate, outstanding resistance to high temperatures, water stability, and fatigue resistance. Such exceptional properties render these materials qualified for usage in road surfaces under heavy traffic conditions, elevated summer temperatures, and other challenging utilization scenarios [1]. Moreover, it is demonstrated that higher grouting fullness contributes to superior road performance characteristics in the context of semi-flexible pavement.

A Review Study on the Improving the Hot Mixture Asphalt Properties by Using Different Types of Polymers as Additive for Asphalt Material

By integrating the design of high-performance material with solid structural design, flexible pavement performance can be increased and the service life extended. In the context of creating highways the topic of asphalt polymer modification and the incorporation of polymers in asphalt material by mechanical mixing or chemical reaction, has received substantial scholarly coverage. A wide range of polymers types are used in the method of changing asphalt material and subsequently enhancing hot mixed asphalt. The main objective of this paper is to review prior research on employing polymer materials to develop the qualities of asphalt cement and hot mixed asphalt. This study reviews three different types of polymers. These polymers are Styrene-butadiene-styrene (SBS), polytetrafluoroethylene (PTFE), and polyvinyl chloride polymers (PVC). According to earlier studies in this area, these polymers are elastomers and plastomers that are utilized to enhance the mechanical properties of hot-mix asphalt while also increasing the stability, elasticity, and stiffness of asphalt binders. The overall performance of asphalt pavement can be achieved by reducing the possibility of rutting in the summer and cracking in the winter.

Laboratory Investigation and Machine Learning Modeling of Road Pavement Asphalt Mixtures Prepared with Construction and Demolition Waste and RAP

Due to the decreasing availability of virgin materials coupled with an increased awareness of environmental sustainability issues, many researchers have focused their efforts on investigating innovative technological solutions in the civil engineering domain. This paper aims to evaluate the suitability of construction and demolition waste (C and DW) and reclaimed asphalt pavement (RAP) reused within asphalt mixtures (AMs) prepared for the binder layer of road pavements. Both hot and cold mixing methodologies were investigated. The technical assessment was based on the volumetric and mechanical suitability, according to saturated surface dry voids (SSDV) and indirect tensile strength (ITS) tests carried out at 10 °C, respectively. Laboratory findings showed that all the hot AMs matched the desired target SSDV at the design gyrations number at different optimum bitumen content levels, alternatively showing a non-significant variation or a significant increase in ITS compared to conventional hot mix asphalt. Conversely, the cold AMs with cement and emulsion bitumen showed a greater volume of voids and moisture sensitivity, and lower temperature susceptibility compared to hot AMs, reaching, on average, 11% lower ITS when using coarse C and DW aggregates and 43% lower ITS when using filler from C and DW. These volumetric and mechanical properties were modeled by means of support vector machines and categorical boosting (CatBoost) machine learning algorithms. The results proved to be satisfactory, with CatBoost determination coefficients R2 referring to SSDV and ITS equal to 0.8678 and 0.9916, respectively. This allowed for the mechanical performance of these sustainable mixtures to be predicted with high accuracy and implemented within conventional mix design procedures.

THE EFFECT OF SEAWATER SOAKING ON THE STABILITY OF AC-WC MIXTURES USING KOYA AGGREGATE, JAYAPURA CITY

Roads are the basic infrastructure in driving the regional economy, so a good pavement structure is needed. One of the factors of road damage is standing water, for roads around the coast are likely to be inundated by sea water. Asphalt Concrete Wearing Course (AC-WC) is one of the concrete asphalt layer which is able to provide good carrying capacity and waterproof layer for road structures. Some areas in kota Jayapura such as Koya have a large number of local aggregates. This study used oil asphalt as a binder, local aggregate for hot asphalt mixture, and saw the effect of sea water immersion in the asphalt mixture. The purpose of this study is to determine the volumetric value and Marshall value of the Laston AC-WC mixture against sea water immersion and without immersion. The material used is oil asphalt from PT. Pertamina and local aggregates from the Koya area. The research carried out is an experimental test in the laboratory, where the resulting asphalt concrete mixture (AC-WC) will be treated with sea water immersion, then Marshall characteristics testing will be carried out to determine its durability value. Based on the tests carried out, the results showed that the volumetric value and the marshall value of the samples treated with immersion did not provide a significant difference in values compared to normal samples. The results of the marshall value, namely the stability of all asphalt levels meet the specifications, while for flow only the asphalt content of 5.5% and 6% both by soaking and without soaking.

Effect of differently treated recycled concrete aggregates on Marshall properties and cost-benefit of asphalt mixtures

Marshall properties are one of the major requirements for designing hot asphalt mixtures. These properties need to be evaluated to make sure that asphalt pavement performs well over its service life. The evaluation of the Marshall properties of asphalt mixtures containing coarse recycled concrete aggregates (RCA) was the study's main target. RCA properties differ from virgin aggregate in the presence of cement mortar. To improve RCA properties, two methods were adopted. The first, termed pre-soak treatment, consisted of soaking RCA in acetic acid for 24 hours at a concentration of 0.1 M. The second one, termed mechanical treatment, involved placing RCA inside the Los Angeles machine with balls and running it for 500 cycles. RCA was incorporated into asphalt mixtures at percentages 20, 40, 60, 80, and 100% of coarse virgin aggregate. The results of the study showed that replacing virgin aggregate with RCA led to economic feasibility. Despite the amount of asphalt binder increasing as coarse RCA content increased, the characteristics of HMA were not significantly altered except for Marshall stability. The maximum increase in Marshall stability happened in the mixture containing 60% untreated RCA; it was 14.78% greater than the control mixture.

Rock Wool Fiber-Reinforced and Recycled Concrete Aggregate-Imbued Hot Asphalt Mixtures: Design and Moisture Susceptibility Evaluation

Designing asphalt mixtures for pavement construction by controlling the moisture-mediated damage remains challenging. With the progression of time, this type of damage can accelerate deterioration via fatigue cracking and rutting unless inhibited. In this study, two types of hot asphalt mixtures (HAMs) were made by incorporating recycled concrete aggregates (RCAs), which were reinforced with rock wool fibers (RWFs). The first specimen was a normal mixture with a completely virgin aggregate, and the second one was a sustainable mixture with 30% RCAs. The proposed mixes were thoroughly characterized to assess the impact of RWF incorporation at various contents (0.5, 1, 1.5, and 2%) on moisture resistance. The optimal asphalt concentration (OAC) and volumetric parameters of the mixes were determined using the Marshall technique. The moisture susceptibility of the obtained HAMs was evaluated in terms of the tensile strength ratio (TSR). The results revealed that the moisture resistance, Marshall stability, flow, and volumetric parameters of the HAMs were improved due to the reinforcement by RWFs, indicating a reduction in the moisture sensitivity and an increase in TSR%. In addition, the HAMs designed with 1.5% RWFs displayed the highest TSR% (11.37) and Marshall stability compared to the control mix. The observed improvement in the moisture resistance and Marshall attributes of the prepared HAMs was ascribed to the uniform distribution of the RWFs that caused a well-interconnected structure and tightening in the asphalt concrete matrix. It is asserted that the proposed HAMs can be nominated for the construction of durable high-performance pavements.

Utilizing marble and granite industry waste in asphalt mixtures for enhanced road performance and sustainability

Incorporating waste into highway construction has shown to be a promising approach for mitigating environmental impacts and reducing production costs by decreasing the consumption of virgin raw materials. In this context, this study investigated the feasibility of using marble and granite industry waste as a partial and total substitute for filler in hot asphalt mixtures. Physical analyses of the constituents were carried out, and the asphalt mixtures were designed using the SUPERPAVE methodology. The filler content obtained was 2 % for the upper gradation curve determined during the dosage process. Subsequently, the marble and granite residue was added in proportions of 50 % and 100 % by weight, replacing the commonly used filler, hydrated lime. The asphalt mixtures were evaluated for their mechanical performance through tests for tensile strength and resilient modulus. The data obtained were subjected to statistical analysis using the Student's t-test with a significance level of 5 %. The results indicated that asphalt mixtures with marble and granite waste exhibited slightly superior mechanical performance compared to the control mixture (with 0 % residue). The statistical test revealed no significant differences between the mixtures for the conducted tests. Additionally, the production costs per ton and per kilometer of highway were practically the same for all three types of evaluated mixtures. In conclusion, the addition of marble and granite industry waste as filler, both partially and entirely, is feasible from both technical and economic perspectives, as it demonstrated equivalent performance to the control mixture. This approach also represents a means to minimize environmental impacts by reducing the demand for raw materials (hydrated lime) and contributing to the proper disposal of waste generated by the ornamental rocks industry.

Recycling of industrial and construction waste materials in roads construction

ABSTRACT Usually, aggregates used for asphalt mixtures consist mainly of natural aggregates. Sometimes the natural aggregates are substituted with limited amounts of industrial and construction wastes. The current paper deals with evaluating the mechanical performance of new developed hot asphalt mixtures made of up to 98% industrial and construction by products. In this project, different types of industrial by-products, namely, RAP, foundry sand, and steel slag in addition to biobased rejuvenators have been used to find the composition of the best asphalt mixtures made mainly of wastes that can substitute the asphalt mixtures made of natural aggregates. Fourteen selected asphalt mixtures have been evaluated using the circular road simulator test at VTI. The CRS testing program has been set up to allow different measurements, e.g. surface deterioration and wear, friction, and visual inspection. The test results demonstrated that it is possible to obtain paving mixtures with high content of recycled materials.

Effect of Blending Behavior on the Performance of Hot Recycled Asphalt Mixtures

Blending behavior is the main factor influencing hot recycled asphalt mixtures’ actual and design performance. The following steps were taken to investigate the above issues. Firstly, the component changes of asphalt mixtures were studied by thin-layer chromatography, with flame ionization detection to obtain the mechanism of asphalt aging and recycling. Secondly, according to the difference in the recycled asphalt components, the hot recycled asphalt mixtures were optimized based on the Marshall design method. Lastly, the hot recycled asphalt mixtures for the three mixing processes were prepared using the optimized design method described above. Laboratory tests were conducted to evaluate the correlation between the degree of blending (DoB) and the high-temperature stability, low-temperature crack resistance, water stability, and fatigue performance. The test results indicate that reducing light components (saturates and aromatics) and increasing heavy components (asphaltenes and resins) are the main reasons for asphalt aging, and asphalt recycling is an inverse process. Additionally, the performance of hot recycled asphalt mixtures is improved with an increase in DoB. Specifically, the DoB is only 50% to 60% under a normal mixing process, but by adjusting parameters the DoB will increase to 80% to 90%.

The Effect of Wetfix and Nanohydrated Lime Additives on Bitumen Aging and the Cohesion and Adhesion Failure Mechanisms of Hot Asphalt Mixtures

Aging due to sunlight and the passage of time is an effective element in the occurrence of moisture damage in hot asphalt mixtures. Still, the effects of this parameter are scarcely considered in the experiments examining the moisture damage potential. Accordingly, this study investigated the effect of aging on the performance of hot asphalt mixtures and examined the improvement of moisture damage performance by using antistripping additives via mechanism and functional tests. Two types of aggregates (limestone and granite) with different degrees of moisture sensitivity, two types of bitumen (PG64-16 and PG58-22) with different performances, and two additives (Wetfix liquid additive and nanohydrated lime) as bitumen modifiers were used. Bitumen samples and asphalt mixtures were subjected to short- and long-term aging. The pull-off test was performed to explore the aging effect on different failure mechanisms (cohesion and adhesion), and the indirect tensile stiffness modulus (ITSM) test was conducted to study the asphalt mixture’s performance against moisture damage. The results specify that aging, in terms of hot asphalt mixture hardening in dry and wet conditions, decreased the MSR (resilient modulus wet to resilient modulus dry ratio), and this decline was greater in long-term aging. The pull-off test results exhibited that aging, especially in the long term, decreased the asphalt mixture’s adhesive strength in dry and wet conditions; this decline in adhesion was greater in the wet than in the dry state, and this difference decreased the wet-to-dry adhesion strength ratio (the pull-off ratio). The additives relatively improved the yield modulus of the asphalt mixture, but their effect was greater in the wet state. A comparison of the pull-off test results in cohesion and adhesion failure demonstrated that Wetfix was more effective in improving bitumen–aggregate adhesion, whereas nanohydrated lime was more effective in enhancing bitumen adhesion. The resilient modulus (Mr) ratio in wet-to-dry conditions indicated that nanohydrated lime had better effects on the overall performance of the aged asphalt mixture against moisture damage. To investigate the effect of additives on the performance of asphalt mixtures, a t-test was performed in all modes of control, short-term aging, and long-term aging. The findings showed the effect of Wetfix and nanohydrated lime on increasing the modulus of elasticity of the samples.

Pengaruh Karet Remah Terhadap Stabilitas Campuran Beraspal Laston AC-WC Menggunakan Metode Dry Mix

Roads must have the appropriate mix of thickness and design to protect the subgrade from damage and to accommodate the load pressure on the road. The purpose of this research is to investigate the effects of adding crumb rubber to the hot asphalt mixture of the Laston AC-WC type. The research was conducted in two stages, involving the creation of test specimens. In the first stage, the bitumen content of the specimens included 5%, 5.5%, 6%, 6.5%, and 7%. In the second stage, In the second stage, crumb rubber was added to the mixture at percentages: 0%, 5%, 10%, 15%, and 20%. The crumb rubber was mixed using the dry mix method. Several parameters were considered based on the results of the Marshall Test, in accordance with the General Highways specifications (VFA, VIM, VMA, Stability, Meltability and MQ). characteristics analysis aims to determine the impact of crumb rubber content on the elasticity, durability, and other properties of the asphalt mixture. Of all the variations of the hot mix asphalt type Laston AC-WC mixed with crumb rubber; the optimum level of crumb rubber mixture was obtained at 5% for the hot mix asphalt type Laston AC-WC. From the research results, when 5% crumb rubber was added to the asphalt mixture, the following values were obtained: 856.1 kg stability, 3.07 mm flow and 290.40 kg/mm MQ. In contrast, the stability value of hot asphalt concrete asphalt concrete type AC-WC with 5% asphalt has 813.7 kg stability, 3.03 mm flow and 268.30 kg/mm MQ.

Characterization of Asphalt Mixtures with Addition of Drill-Well Gravel

One of the by-products of the oil industry that is disposed of in nature as waste is oil well gravel. When improperly disposed of, it pollutes the soil, deteriorates the urban landscape, and constitutes an environmental liability if it is destined for landfills without prior treatment. As a way of reusing gravel from oil wells, this research proposed using gravel as a filler in hot asphalt mixtures. This study evaluated hot asphalt mixtures dosed with 2% filler by the Superpave methodology. The 2% filler was partially replaced by the oil well gravel (1% gravel and 1% lime) and totally (2% gravel), compared to the use of 2% lime as a commonly used filler in traditional blends. Rheological tests such as rotational viscosity, performance grade (PG), creep and recovery under multiple stresses (MSCR), and linear sweep amplitude of strain (LAS) were carried out in order to investigate the effects on asphalt mastic when incorporating oil well gravel in the contents proposed. The asphalt mixtures were evaluated through mechanical tests: tensile strength, modulus of resilience, dynamic modulus, flow number, and modified Lottman. The rheological evaluation could prove the gain in viscosity and stiffness of the asphalt binder, showing less susceptibility to thermal variation and, consequently, an increase in the resistance to permanent deformation. It was also found that the incorporation of the gravel residue caused a reduction in the resistance to damage and shorter fatigue life to the binder at the highest deformation amplitudes. The use of gravel from oil wells did not cause a significant change in the mechanical performance of the asphalt mixtures at the tested contents, presenting itself as a sustainable option for use mainly in regions with low rainfall, such as the Northeast region of Brazil.

Viability of Asphalt Mixtures with Iron Ore Tailings as a Partial Substitute for Fine Aggregate

Dark colors aggravate the absorption and accumulation of heat in urban centers in the layers of asphalt coating. These problems can be minimized by incorporating materials that increase the albedo on these pavements. The use of waste in the industry has been encouraged, and an alternative is iron ore tailing (IoT), whose material comes from processing iron ore. The circular economy encourages a change in waste disposal after project decommissioning, encouraging the transformation, reuse, and recycling of waste. Therefore, this research investigated the influence of percentages of IoT in the contents (7.5%, 10.0%, and 12.5%) as a substitute for fine natural aggregate on hot asphalt mixtures’ mechanical and thermal performance. The statistical variance test (ANOVA) was used to validate the obtained data. An economic analysis concerning the costs of production and recovery of asphalt mixtures was carried out using the Present Net Value. Asphalt mixtures with IoT were evaluated with regard to the environmental aspect using the circularity index. Among the asphalt mixtures analyzed, the one produced with 12.5% was the most viable. The results showed a gain in mechanical performance concerning tensile strength, resilient modulus, fatigue, and permanent deformation of this mixture, as well as a reduction in production costs per kilometer of highway. The use of 12.5% provided a greater circularity and a reduction of the surface temperature of the pavement by 2.9°C. IoT is viable in constructing highways close to places that produce iron ore.

Performance and cost evaluations of 100% recycled hot asphalt mixtures for pothole patching applications in flexible pavements

Fixing the potholes using bituminous patching mixtures is a critical and costly pavement maintenance activity. The patching mixture's quality significantly affects patch durability and performance; always using the best material available is advisable. This study investigated the feasibility of using 100% hot recycled asphalt pavements (RAP) as a possible patching material by comparing the performance results with cold patching mixtures (CPM) as well as Superpave hot mix asphalt (SHMA) mixtures. Four different RAP mixtures, two fine-graded and two coarse-graded, from two distinct sources, are obtained. RAP mixtures were handled in a laboratory environment to obtain the hot recycled patching materials. Three different rejuvenators were incorporated into hot-recycled pavement material (HRPM) at manufacturer-recommended dosages to determine the best rejuvenator type. Performances of the mixtures are evaluated in terms of linear viscoelastic characterization, permanent deformation, and low-temperature thermal cracking potentials using dynamic modulus, flow number, and indirect tensile strength tests, respectively. The results show that RAP mixtures with any RAP source, gradation, and rejuvenator type outperformed CPM in performance tests and behaved similarly to SHMA mixtures.

Effect of Additive Addition on RAP (Reclaimed Asphalt Pavement) as an Aggregate Substitution Against the Upper Surface Layer of The Road

As development in the field of infrastructure increases, it will require more materials of natural origin. The availability of materials from nature will be reduced and more limited. Meanwhile, the construction of infrastructure continues to run every year for the improvement and comfort of the community. With this, the importation of goods will also increase, especially for bulk asphalt materials, and it is possible that later the stone that becomes one of the main materials for hot asphalt mixture will also bring in from abroad. If waste from peeled asphalt (RAP) can be reused, it will automatically reduce the use of materials from nature and reduce import activities of goods which results in reduced state expenditure. The thesis task will discuss the reuse of peeled asphalt (milling) on the highway, starting from the benefits of RAP, the advantages of RAP, testing RAP materials and new materials, and how to produce RAP asphalt at the Asphalt Mixing Plant. The composition of the RAP used is 60% with SW1 rejunevile material of 3.8%, the addition of new aggregates of 40%, and the addition of new asphalt of 3.3%. The results of the compaction experiment in the field (trial compaction) which will be used for work reference are initial compaction (tandem roller 2 passing), intermediate compaction (tire roller 16 passing), and final compaction (tandem roller 1 passing), and the resulting density of hot mix beds of 98.36%.

The effect of asphalt emulsion type on the characteristics of cold asphalt emulsion mixtures

The need for road infrastructure continues to increase affecting the increase of hot asphalt mixtures. Hot asphalt requires a lot of energy to use because it goes through a heating process, so Cold Emulsion Asphalt Mixture (CAEM) is widely studied to be an eco-friendly alternative to hot asphalt mixtures. This study used a type of mixture IV Asphalt Emulsion Mixture with 4 types of emulsified asphalt, which are Cationic Slow Setting-1 hard (CSS-1h), Cationic Medium Setting-2 (CMS-2), Cationic Rapid Setting-2 (CRS- 2), and Cationic Quick Setting-1 hard (CQS-1h). The test was carried out using the Marshall Test method and the parameters value of each type of emulsified asphalt was calculated. The test results are compared with their characteristics to determine the most suitable type of emulsified asphalt for heavy traffic in Indonesia. The results showed that CRS-2 emulsified asphalt was not recommended because it had low stability and did not meet the parameter requirements. The use of CQS-1h is recommended because at an early age it can produce high stability value and meet all requirements.

Increasing the Content of Reclaimed Asphalt in Asphalt Mixture by using Rejuvenators

Recycling pavements is beneficial on various levels, since using reclaimed asphalt (RA) has a positive effect on the economy and environmental protection at the same time. Removed old asphalt pavement is no longer considered as a waste material, which has to be landfilled, but a useful material for further applications. Leading to a reduction of the need for virgin materials and preserve the planet. At the start, RA was used for construction of embankments and unbound granular layers, later cold recycling became another effective solution. After years of experiments, the rate of RA has increased to reach even the 100 %. But typical RA content in hot asphalt mixtures is between 25 % to 40 %. The presence of RA in the asphalt mixture has a negative effect on the mixture properties. Two alternatives were used in order to soften the aged bitumen – use of softer binder or special additives, i.e., rejuvenators. This study evaluated the possibility of increasing the RA content (30 % and 50 %) in asphalt mixture by adding mainly bio-based alternative rejuvenators. Mechanical performance was evaluated by means of laboratory investigations for typical characteristics dedicated to durability, stiffness, and cracking potential.

Fatigue Performance of Recycled Asphalt Mixtures: Viscoelastic Continuum Damage Approach and Cost Analysis

This study aims to evaluate the fatigue phenomenon in recycled hot asphalt mixture for an asphalt surface layer. Eight mixtures were evaluated in the laboratory, and the samples were divided into two major groups: four mixtures containing neat binder and RAP from source 1 (RAP with neat binder) and four mixtures containing SBS-modified binder and RAP from source 2 (RAP with SBS-modified binder). The levels of RAP incorporation were 0%, 10%, 20%, and 30% in relation to the total weight of the mixtures. The mixtures followed the Marshall mix design methodology. The results indicate that mixtures with polymer-modified binder presented better performance, whereas the addition of RAP slightly decreased the resistance to fatigue cracking. In terms of economic analysis, the use of RAP, for all cases, leads to a reduction in production costs due to the reduction of the binder and aggregate added, with savings of up to 14.1% in the case of 30% of RAP for the SBS binder. When evaluating the economic impact of inserting RAP and its relationship with fatigue performance in the long term, it can be observed that the type of binder added impacts the results: mixtures with SBS binder present economic gains within acceptable quality parameters up to 30% RAP insertion; for mixtures with neat binder, the percentage of up to 10% RAP is advantageous.

Recycling of polymer modified bituminous mixes with reclaimed asphalt pavement – An experimental study

Recycling is an attempt to effectively utilize the used material to manufacture new material of acceptable or if possible superior quality materials. Recycling promotes resource preservation, energy efficiency, and cost-effectiveness in manufacturing. Recycling can be effectively applied for bituminous pavements. The scarified bituminous material from the surface course can be mixed with fresh aggregates and/or fresh binder to relay new pavements performing the same function as in the original application. Thus scarified bituminous material, which is milled from asphalt surface is recycled in hot mix asphalt. Hot mix recycling has shown to be an effective method due to its low cost and capacity to produce mix of a high calibre. Thus, reclaimed asphalt pavement recycling is necessary for use for technical, economical, and environmental reasons. The purpose of the study is to assess the effectiveness of hot asphalt mixtures using recycled asphalt pavement (RAP). Bituminous material that had been scarified was obtained for the current investigation from a national highway in Belagavi, India. It was discovered that the project location has a BC-II and PMB-40 gradation. The site-recycled material underwent a bitumen extraction test to determine its gradation and binder concentration. In the current laboratory experiment, four different sorts of mixes were created and put to the test. New bituminous mixes were made using the BC-II gradation. Two mixes were proportioned, and recycled materials were used to partially replace the coarse and fine aggregates in the BC-II mix, respectively. The mixes were produced using the Marshall approach and the MS-2 criterion. The mixes were investigated in terms of their Marshall properties, moisture susceptibility through ITS & TSR tests. The recycled mix when combined with fresh aggregates and binder to compensate for loss in gradation and ageing of binder respectively results in a mix of properties similar and even better than fresh bituminous mix.

ENVIRONMENTAL IMPACTS OF USING FOAMED ASPHALT

Introduction. There has been a world-wide tendency, a global trend to reduce energy demand using a wide variety of methods. With this, on the one hand, the goal is to conserve the limited available and increasingly expensive energy carriers, and on the other hand, it is strived to reduce the emission of greenhouse gases and thereby fight against climate change. Problem statement. In the field of road construction, the most widespread manifestation of this sustainability endeavour is the goal of replacing high-energy, hot asphalt mixtures (HMA) with variants of suitable quality. It is a common experience that in this field, the so-called warm asphalt mixtures (WMA) can be the most effective solution. Purpose. The purpose of this article is to examine the environmental effects of the WMA. The authors of the article also deal with whether the type of substitute asphalt mixture does not represent a (long-term) performance reduction in the asphalt layers. Materials and methods. Environmental safety of asphalt mixing plants is a growing concern nowadays due to the high temperature of asphalt mixture production requiring a lot of energy, and resulting in much air pollutants released into the air. The comparison between hot mix asphalt (HMA) and warm mix asphalt (WMA) was performed using BEES (Building for Environmental and Economic Sustainability) 4.0 model; just now the environmental features of the two asphalt mixture types was concentrated on. (The model has also an economic element).