Foamed Bitumen Research Articles

Application of NaP1 Zeolite Modified with Silanes in Bitumen Foaming Process

In recent years, global climate change has caused worldwide trends in science and industry toward a focus on the development of modern technologies with reduced environmental impact, including reduced CO2 emissions into the atmosphere. The technology for producing asphalt mixtures (AM) at lower temperatures (WMA—warm asphalt mix) using zeolite materials for the bitumen foaming process fits perfectly into these trends. Therefore, towards the development of this technology, the research presented in this paper presents the modification process of zeolite NaP1 from fly ash with silanes of different chemical structures (TEOS, MPTS, TESPT) and their application in the foaming process of bitumen modified with polymers (PMB 45/80-55). The scope of the work includes two main novelty elements: (1) the use of zeolite–silane composites in bitumen foaming and (2) polymer-modified bitumen foaming. Chemical characterisation carried out by EDS-XRF, FTIR, and XPS analysis clearly demonstrated the success of the zeolite matrix modification process, which directly resulted in textural changes. Simultaneously, mineralogical analysis carried out by XRD showed the complete retention of the initial phase composition of zeolite matrix. Further studies have shown that the application of zeolite–oxide composites results in less PMB 45/80-55 stiffening without imposing negative effects on its softening point and dynamic viscosity.

Development of Bitumen Selection Criteria for Cold Recycled Bituminous Mixes with Foamed Bitumen

Development of Bitumen Selection Criteria for Cold Recycled Bituminous Mixes with Foamed Bitumen

ТЕХНОЛОГІЇ ХОЛОДНОГО РЕСАЙКЛІНГУ ДЛЯ ГЛИБОКОЇ РЕГЕНЕРАЦІЇ НЕЖОРСТКОГО ДОРОЖНЬОГО ОДЯГУ

ntroduction. In the introduction to the article, the briefly performed comparative analysis of the road asphalt concrete cold recycling technologies was adduced and also the actuality of the implementation of widened nomenclature of such technologies in the Ukraine was outlined. Problem statement. The issue of the article concerns processes and materials for technologies of the full-depth reclamation of flexible road pavements using cold recycling trough full depth of asphalt layer/layers including the underlying layers of granular materials as required. Purpose. The aim of the article is to analyze the technological parameters of processes of full-depth reclamation (FDR) and also general requirements for reclaimed materials especially those concerning the estimation of their thermorheological properties. Results. The methods of the reclaimed materials stabilization were examined which, in accordance with the FDR technologies, should be divided in mechanical and those performed with the stabilizing agents. The types of pavement defects were defined under presence of which the application of FDR technologies has been recognized highly effective. The concise analysis of general requirements for reclaimed materials was performed with setting off the materials subjected to special requirements for grading. Also, the technological particularities of processes of the full-depth reclamation were stated which should be attributed to the technical characteristics of road equipment, the road pavement condition, and reclaimed mixtures quantitative proportions as well. According to the analysis of the test methods of reclaimed materials stabilized by bitumen using foamed bitumen, the role of the thermoreological uniformity of cold recycled mixtures for their proper design was shown.

Influence of physical properties and chemical compositions of bitumen on foam characteristics

This study explores the influence of intrinsic bitumen properties on foam characteristics, considering physical properties (penetration, softening point, viscosity), chemical compositions (SARA components, FTIR indices), and physico-chemical characteristics [surface free energy (SFE)]. Ten distinct bitumen samples from two different sources were analyzed. The results reveal that physical properties alone do not sufficiently account for variations in foaming potential among bitumen types. However, chemical compositions and SFE proved to be more informative, explaining the differences in maximum expansion ratio and foam index, specifically for bitumen from the same source. In contrast, when bitumen originates from different sources, none of these intrinsic properties can clarify foaming potential. Notably, intrinsic bitumen properties fail to elucidate the variability in the half-life of foamed bitumen, even when the bitumen types share the same source. These findings underscore the significance of considering multiple factors when assessing bitumen's foam characteristics, particularly when evaluating materials from diverse sources.

Effectiveness of different conditioning procedures for moisture susceptibility evaluation of foamed bitumen stabilised mixes

ABSTRACT The primary objective of the present study is to evaluate the effectiveness of the widely used moisture conditioning methods for moisture susceptibility evaluation while designing the Foamed Bitumen Stabilised Mixes (FBMs). The effectiveness of three different moisture conditioning methods, such as the conventional 24 h of water soaking, vacuum saturation (AASHTO T283), and ASTM D7870 conditioning (hydrostatic pore pressure) were compared based on their ability to distinguish between moisture susceptible and moisture damage resistant FBMs. It was observed that the ASTM D7870 moisture conditioning method could distinguish between moisture-resistant and moisture-susceptible mixes more effectively compared to the existing 24 h of water-soaking method, and can potentially be a more suitable conditioning method for moisture susceptibility evaluation of FBMs. The study also recommended threshold moisture susceptibility criteria in terms of retained tensile strength (TSR) for the ASTM D7870 conditioning method based on the existing moisture susceptibility criteria for 24 h of water soaking by performing Receiver Operation Characteristics (ROC) analysis on the TSR results. For different TSR criteria of 80%, 70%, and 60% for 24 h of water soaking, the equivalent TSR threshold for ASTM D7870 conditioning is recommended as 60%, 55%, and 50% respectively.

The effect of active filler type, compaction method and slag-based geopolymer on volumetric and mechanical properties of cold foamed bitumen mixes with 100% RAP

Cold in-situ recycling with foamed bitumen has become one of the most cost-effective and sustainable technologies due to working with low heating energy, less transport, and decreasing the use of new materials. This paper presents a benchmark laboratory study of the volumetric and mechanical properties of cold recycled foamed bitumen mixes blended with 100% reclaimed asphalt pavement (RAP) in the granular base layer. The air void content, indirect tensile strength, and resistance to moisture damage are tested to evaluate the impact of active filler, compaction technique, and geopolymer. It was found that the addition of active filler, regardless of the type, increased the moisture resistance between 30% and 35% compared to the mixture with no active filler. Moreover, the addition of slag-based geopolymer resulted in a substantial increase in tensile strength from 434 kPa to 823 kPa while leading to a sharp decrease from 70% to 38% in moisture resistance.

Use of a machine learning-based framework to approximate the input features of an intrinsic cohesive zone model of recycled asphalt mixes tested at low temperatures

Although the cohesive zone model (CZM) provides numerous advancements in simulating the crack initiation and evolution in asphalt mixes, its efficiency and applicability are still challenging. This is because asphalt mixes are principally assumed to be homogeneous in CZM modeling despite intrinsic heterogeneity. Therefore, it is essential to calibrate the CZM model, by adjusting the input factors, aiming at alleviating this inconsistency between the model and reality. Accordingly, this research was aimed at presenting a model to approximate the calibrated input features as a function of a wide variety in testing conditions and mix criteria. To this end, an experimental dataset was collected by investigating the fracture mechanic responses of various recycled warm asphalt mixtures (prepared using three categories using organic and chemical materials, and using foam bitumen technology). Mixes were consisted of virgin aggregates and those containing up to 70% recycled asphalt pavement particles (i.e. 0, 30, 50, and 70%). Mixes were subjected to freeze and thaw cycles (i.e. 0, 1, and 3 cycles) and semi-circular bending test was conducted at subzero temperatures (i.e. 0, −10, and −20℃). Experimental results were analyzed using machine learning (ML) algorithms including random forest, gradient boosting regression, and multi-output regression methods. The results proved the efficiency of the random forest regression model in predicting the required input factors of CZM model. The ML model was also validated by predicting the input factors (of CZM model) for another fracture dataset, demonstrating that this ML model can be promisingly used as an approximation tool.

The Influence of Recycled Materials on Cold Mix with Foamed Bitumen Properties.

The utilization of recycled materials is an important issue in the context of environmental protection. The large amounts of recycled material recovered from the demolition of asphalt road structures indicate the need to find new ways of utilizing them. In the case of road renovation projects, large amounts of recycled materials are, in most cases, recovered in the form of reclaimed asphalt pavement (RAP), reclaimed concrete (RC) and recycled aggregate (RA). To focus on the effects of the use of recovered materials (RAP, RC and RA), the same composition was used for all of the analyzed mixtures in terms of foamed bitumen (FB) and Portland cement (CEM) content. The scope of laboratory tests included the specification of the following parameters: the amount of air void content Vm, the determination of axial compression strength at +25 °C, indirect tensile strength (ITS) at +25 °C, water resistance, TSR, water and frost resistance, WRW+M stiffness modulus (IT-CY) at 13 °C, dynamic dynamicmodulus. The plan of the experiment assumed addition recycled material in quantities between 20% and 80% in increments of 20%. The obtained results indicate that both the type and quantity of recycled material significantly affect the properties of the cold-recycled mixture with foamed bitumen. Using reclaimed asphalt pavement and recycled cement concrete guarantees high levels of stiffness in the recycled mixture. Howeverin the case of recycled aggregate, the authors did not observe any visible changes in the dynamicdynamic modulus, irrespective of the loading conditions. It was also indicated that it is necessary to reduce the quantity of reclaimed asphalt pavement in the composition of the FB-RCM mix to maintain the required air void content.

Investigation of Cold Recycling of Bituminous Surface Treatment with Foam Bitumen

The course of turned of bituminous pavement layers into hot mix asphalt (HMA) layers has been increasing day by day all over the world. Bituminous surface treatment that contains consirable amount of aggregate and bitumen, is an important source of recycling that offers a great amount of pavement materials intead of virgin material usage on pavement consruction. In the study, it was aimed to investigate the usability of bituminous surface layer treatment in the base layers of the HMA roads by mixing with foam bitumen and active filler materials in order to eliminate the potential performance degradation that will be encountered when it is recycled due to the low bitumen percentage compared to hot mix asphalt and the wear of the aggregate due to climatic conditions and traffic loads over time. The study conducted that intends to technically evaluate the cold recycling of bituminous surface treatment of roads with foam bitumen and active filler materials; for 70/100 bitumen grade, 5 different bitumen mixes were prepared and ideal bitumen percentage was investigated for this bitumen grade. The effect of bitumen percentage on mixture performance was evaluated with 50/70-100/150-160/220 bitumen grades and mixtures were prepared in single bitumen ratio (2.5%). It was investigated that active fillers will give suitable results for foam bituminous mixtures by preparing mixtures for three different active fillers; cement, hydrated lime and fly ash. To evaluate all these productions, ITS, unconfined compressive strenght, triaxial resilient modulus and asphalt permanent deformation tests were performed. The results obtained showed that production made using 2% foam bitumen and 1% was found suitable for moisture sensitivity and structural stability. Recycling of bituminous surface treatment using foam bitumen and cement is an environmentally and economically beneficial method by reducing both waste and raw material consumption.

Investigation of the Usability of Foamed Bituminous Mixtures as Bituminous Base Course

Materials recycled with foam bitumen are promising materials for pavements economically and environmentally. However, there are different opinions in the literature about how these materials are positioned in the pavement. It is clear that their performances will not be suitable for the wearing course, but that they are used for the plant mixture base course because they contain bitumen, and that these materials will be neglected in the evaluation of these materials. In the study, 4 different foam bituminous mixes prepared with a recycled pavement material and a standard bituminous base course mix were compared in terms of the resilient modulus obtained from the uniaxial indirect tensile resilient modulus test. Gradation is the same for three of the mixtures, two of them use cement as a mineral binder, but 70/100 grade bitumen in one of these two productions and 50/70 grade bitumen in the other. In the third mixture, 70/100 grade bitumen and hydrated lime (HL)+fly ash (FA) were used. In the final mixture, 70/100 grade bitumen and cement were used as mineral binders, but gradation was changed. In addition, permanent deformation control for the final production was carried out with a triaxial cyclic compression test. It was concluded that all these variables affect the results, but the resilience modulus values obtained for all were quite close to those obtained from the bituminous base sample. Considering that the foamed bituminous mixtures will be thicker than the bituminous base course in practice, it is considered structurally appropriate to use this layer instead of the bituminous base course.

Optimum Fluid Content in Pavement Cold In-Place Recycling Containing Waste Materials

The planning of road infrastructure undergoes major changes, especially in terms of sustainable development. Recycling of pavement structures involves the reuse of materials from existing pavement structures due to its timesaving and environmental benefits, as well as cost reduction. According to the recycling temperature, recycling can be hot and cold. This paper deals with cold in-place recycling and the determination of the optimum fluid content for by-product materials in mixtures compared with one containing natural zeolite. The content of bitumen emulsion and cement—which are the most used materials so far in cold recycling along with foam bitumen—was replaced with fly ash, slag or natural zeolite, and bakelite, respectively, while recycled asphalt pavement from Serbia (Žabalj) was used. Six different mixtures were made. The mixture with the addition of fly ash had the highest optimum fluid content (7.6%) compared with all test mixtures. Mixtures with slag, natural zeolite, and bakelite were in the range of a mixture containing 2% cement. Furthermore, the mixture with 3% cement had the lowest optimum fluid content (5.7%) in comparison to all the mixtures that were tested.

Warm Mix Asphalt Binder Utilizing Water Foaming and Fluxing Using Bio-Derived Agent.

The present paper investigates the effects of simultaneous mechanical foaming using water and fluxing with a bio-derived agent on the properties of three distinct asphalt binders: 50/70 paving-grade bitumen, 45/80-55 polymer-modified bitumen, and 45/80-80 highly modified asphalt binder. The testing involved classical tests for assessing binder consistency (penetration at 25 °C, ring and ball softening point, Fraass breaking point, and dynamic viscosity) as well as performance tests (high and low Superpave critical temperatures and multiple stress creep recovery). The tests included assessment directly after asphalt binder foaming and were repeated after a 14-day period. It was shown that bitumen foaming had only short-term effects on the asphalt binders, which did not persist in the repeated tests after 14 days. The fluxing agent that was utilized caused significant changes in the consistency of all asphalt binders. The changes in the performance characteristics of the 50/70 and 45/80-55 binders were severe and amounted to a significant decrease in high-temperature performance of these binders. On the other hand, an improvement in all performance characteristics in the case of the 45/80-80 asphalt binder was observed as a result of the applied processes, particularly when measured 14 days after foaming. This study shows that the simultaneous use of foaming and the fluxing additive decreased the dynamic viscosity of the 45/80-80 binder, while improving its properties relating the pavement performance.

Technical Investigation of the Usability for Foamed Bitumen Stabilized Materials inAsphalt Pavements

Asphalt recycling efforts are increasing in order to reduce the effects of high energy and rawmaterial consumption in the asphalt sector. One of the most common methods for using oldasphalt material, which still retains some value, is recycling with foam bitumen.In practice, for the preparation and evaluation of cold mixes produced using foam bitumen, ITS(Indirect Tensile Strength) and MR (Resilient Modulus) methods are generally used. Amongthese methods, ITS is mostly applied for the evaluation of the materials optimum percentagesvalues and MR test is also used for the evaluation of mixture performance.In the experimental study, firstly for the cold mixes prepared with foam bitumen, optimum foambitumen values of the production series were determined by ITS test. Then, reproductions weremade for these optimum values and resilient modulus values were determined. It was found thatthe ITS and MR values were significantly affected by the material gradation and this showedthe opposite tendency for the materials with the same gradation. The type of active filler waseffective the same as the values of the mixtures on ITS and MR. Especially, the MR resultswere affected by the bitumen grade. As a result of the study, evaluation limit values; 225 kPafor ITSDRY value, 150 kPa for ITSWET value and 70% for TSR, 400 MPa resilient modulus valueand 0.21 layer coefficient value are recommended for FBSM (Foam Bitumen StabilizedMaterial).

Influence of bitumen foam characteristics on moisture susceptibility of foamed bitumen stabilised mixes

ABSTRACT The objective of the present study is to investigate the effect of foam characteristics of bitumen such as maximum expansion ratio (ERm) and half-life (HL) on the moisture susceptibility of foamed bitumen stabilised mixes (FBMs). The study investigated the individual as well as the interaction effect of ERm and HL on moisture susceptibility of FBMs. Considering the individual effect of ERm, it was observed that for a given HL, the beneficial effect of ERm on the moisture susceptibility of FBMs exists up to a certain level of ERm, beyond which the performance of the FBMs was found to be compromised. On the other hand, at controlled ERm, the higher HL was found to have beneficial effect on the moisture susceptibility of FBMs, provided the controlled ERm was sufficiently high. When the interaction effect of ERm and HL was considered, the FBMs were found to have higher moisture damage resistance with the increase in ERm as long as the HL was above a certain threshold level. The study also proposed performance-based minimum threshold limits for ERm and HL based on the Receiver Operation Characteristics (ROC) analysis on the retained tensile strength (TSR) results obtained for the FBMs prepared at varying foam characteristics.

A Study of Foam Bitumen Preparation for Effective Recycling of Pavement Layers

Foamed asphalt recycling technology can effectively recover waste asphalt pavement materials and achieve the sustainable utilization of resources. This technology’s core equipment is asphalt foaming equipment. Since the asphalt foaming device’s fault data are uncertain, this work proposes a method for evaluating the device’s reliability, combining triangular intuitionistic fuzzy numbers, trapezoidal intuitionistic fuzzy numbers, and expert knowledge. Using the proposed evaluation method, the failure probability of the asphalt foaming device and the importance of the bottom event were calculated. The obtained model results were found to be consistent with the actual collected data, verifying the reliability and validity of the model. Furthermore, the asphalt viscosity is one of the key factors affecting the asphalt foaming recycling technology. In this work, the influence of different viscosities on the asphalt foaming mechanism was investigated using a theoretical analysis. Then, a computational fluid dynamics (CFD) analysis method was employed to simulate the different viscosity asphalt foaming processes, aiming to identify the most suitable one for the production of high-quality foam asphalt in the foaming asphalt viscosity range. Finally, experiments were carried out to verify the results of the analysis. The results show that the asphalt foaming device’s failure probability was around 7.512 × 10−2, and the best foaming asphalt viscosity was in the range of 0.3~0.5 Pa·s.

Experimental investigation of reclaimed asphalt foamed bituminous mix: a cold mix technique

PurposeNatural good-quality sources of aggregates are depleting, whereas large amount of reclaimed asphalt pavement (RAP) is produced annually. Safe disposal and use of RAP in the cold in-place recycling (CIR) using foamed bitumen could be sustainable approach where milling and mixing operations are accomplished simultaneously. This will not only help in minimizing contamination (probability) and transportation cost but also reduces the carbon footprints. Therefore, this study aims to investigate the scope of RAP utilization up to 100% and further its effect on the behavior of reclaimed asphalt foamed bituminous mix.Design/methodology/approachReclaimed asphalt foamed bituminous mix (FBM) is still a new technique. The evidence of performance of 100% recycled pavement (CIR) is only anecdotal and lacks in systematic guidelines and literatures. Foam binder coating around the aggregates is also a concern. Therefore, this study is mainly emphasized to investigate the scope of RAP use in the FBM up to 100%. RAP content is varied in each trial, i.e. 70, 85, 100 and 0% (only fresh aggregates), to make the FBM. RAP use and its effect on the behavior of FBM in terms of resilient modulus, variation in resilient modulus with curing, rutting performance and the potential of resistance against the moisture damage are addressed.FindingsConsidering the laboratory studies, it can be accomplished that mechanistic properties and performance of FBM are largely influenced by RAP material and portray less susceptible characteristics against the moisture damage. FBM containing 70% RAP content exhibits maximum resilient modulus. However, use of RAP up to 100% in FBM is satisfying the minimum required specification.Originality/valueOverall, the study may be helpful to highway professionals and could generate another possible option of 100% RAP replacing fresh aggregates in the flexible pavements.

Characterisation of foam bitumen mixes with diffrent RAP content at elevated mixing temperature using design of experiment (DOE) approach

ABSTRACT Cold recycling using foam bitumen is one of the most popular rehabilitation techniques for bituminous pavements. Effect on mixing temperature reclaimed asphalt pavement (RAP) material content and foam binder content on the performance of foam bitumen mix (FBM) has been evaluated in the present study. This paper discusses the statistical approach adopted for FBM design and the development of the model consisting of three factors which are mixing temperature, foam bitumen content, and RAP material content. The experiment was designed according to the 23 factorial design using the central composite design (CCD) method and the desirability approach was adopted for determining the optimum parameter. Dry and wet indirect tensile strength parameters were considered as responses to optimise the input parameters. Results show that with increasing the mixing temperature of FBM, the performance of FBM improves at lesser binder content. The developed quadratic models using the response surface methodology (RSM) optimisation tool have higher determination coefficients for dry IDT and wet IDT indicating a good model fit between the actual and predicted values. A scanning electron microscope analysis was conducted to evaluate the impact of RAP content and mixing temperature on the dispersion of bitumen in the FBM matrix.

Strength and permanent deformation properties of demolition wastes, glass, and plastics stabilized with foamed bitumen for pavement bases

Foamed bitumen (FB) stabilization is an in-place soil improvement technique that has become popular in recent times. Nevertheless, a lack of understanding exists about the strength and deformation responses of FB stabilized recycled demolition wastes in pavements. This paper aims to introduce the application of FB stabilized recycled demolition waste blends with glass and plastic in the pavement base layer. A suite of laboratory tests was undertaken to evaluate the indirect tensile strength, unconfined compressive strength, California bearing ratio, and permanent deformation behavior of FB stabilized blends. Recycled concrete aggregate (RCA) was blended with recycled glass (RG), recycled plastic (RP), and reclaimed asphalt pavement (RAP) in various percentages and the performance of the FB stabilized blends were characterized through extensive experimental testing. A multi-stage repeated load triaxial (RLT) testing procedure was adopted to evaluate the permanent deformation behavior of the unbound and FB stabilized blends under various stress levels. The ITS, UCS, and CBR values exhibited decreasing trends with increasing the RAP, RG, and RP contents. The permanent deformation of the blends was found to be reduced as a result of FB stabilization, most notably for the blends with higher percentages of RAP, RG, and RP. The permanent deformation responses of the blends were ranked using the shakedown concept that indicated the FB stabilized demolition wastes exhibited relatively stable responses under cyclic loads. The deformation response of the blends with 50%RAP and 7%RP changed from incremental collapse to plastic creep as a result of FB stabilization. The results indicated that the FB stabilization of recycled aggregates is a suitable practice for developing more sustainable roads with enhanced ductility and resistance to rutting.

Exploring the role of extreme thermal conditions and freeze–thaw cycling on crack growth resistance of WMA mixes: an analytical and statistical analysis

ABSTRACT Significance of premature failures, such as thermal cracking, on the in-service performance of asphalt pavements, resulted in exploring how cracking resistance of Warm Mix Asphalt (WMA) is affected by its inherent characteristics. Three WMA technologies consisting of the application of organic materials, chemical agents, and foam bitumen technique, coupled with conventional Hot Mix Asphalt (HMA) were used to prepare WMA mixes. Semi-circular bending test was used to investigate cracking potential of the selected WMA mixes. Statistical analysis, comprising of ANOVA, Tukey pairwise, and Spearman’s ranking-order, showed that indices such as WeibullCRI, RDCI, and FI can be adequately used for ranking WMA mixes. Weibull probability distribution function (Weibull PDF) analysis was also applied to determine effects of the testing factors on their failure probability. Results showed that temperature reduction towards −20°C increases probability of fracture failure. Fracture happened more in Sasobit and Foam WMA mixes. However, effects of moisture level and FT cycles on crack evolution was negligible. Finally, failure probability curves of the various WMA mixes were predicted based on the actual probability curves of the control HMA.

ABOUT MODERN POSSIBILITIES OF REUSING ROAD-BUILDING MATERIALS WHEN REPAIRING ROAD PAVEMENTS OF AN IMPROVED LIGHTWEIGHT TYPE

At present, when developing design solutions for the repair of non-rigid road pavements of an improved lightweight type, they provide for the device of a base layer using cold recycling technology or from a crushed stone-sand mixture treated with a mineral or complex binder, and two layers of asphalt concrete are laid on top. Based on the results of exploratory studies aimed at wider reuse of road building materials, it is proposed, when repairing a road surface of an improved lightweight type, instead of the top layer of a base made of asphalt concrete, arrange a layer of road material made by the technology of cold recycling ” in the mixer” using an organic binder, and the bottom layer of the base should be made of road material made by the technology of cold recycling “on the road” using a mineral or complex binder. Considering that Ukraine has insufficient experience in preparing mixtures using cold recycling technology using foamed bitumen or bitumen emulsion, the features of their manufacture are given. After milling the asphalt concrete, the bottom layer of the base is reinforced from the road material made using the cold recycling technology “on the road” using a mineral or complex binder. Layers of materials arranged according to the technology of cold recycling, due to processing with a small amount of binders, have insufficient resistance to the action of the wheels of vehicles, and therefore, on top of these layers, it is necessary to arrange a coating layer of materials that provide resistance to dynamic action. The given approach allows to obtain a reduction in the cost of pavement repair due to a decrease in energy consumption for the preparation of asphalt concrete, since the production of materials using cold recycling technologies does not provide for heating the material.