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Zusammenfassung Hintergrund: Hausmittel (HM) gelten als Ressource der Selbstfürsorge bei chronischen Erkrankungen. In der BMBF-geförderten, cluster-randomisierten HoPES3-Studie wurde die Nutzung von HM durch ältere Patient/-innen untersucht. Ziel war es, die Aspekte Spiritualität, soziale Aktivität und Selbstfürsorge (durch Beratung zu HM) in der hausärztlichen Versorgung zu stärken. Fragestellungen: Welche Maßnahmen sind zur Selbstfürsorge älterer Menschen geeignet? Wie hoch ist die Anzahl der HM Nutzer/-innen? Welche HM Arten werden angewendet? Welche Einstellungen und Beweggründe haben ältere Patient/-innen hinsichtlich HM Anwendung? Methode: Entwicklung von Infozepten (Anleitungen zur Selbstanwendung von Hausmitteln), Fragebogengestützte Erhebung der teilnehmenden Patient/-innen (n= 297). Leitfadengestützte Interviews mit Patient/-innen (n=29). Ergebnisse: Es wurden 17 Infozepte entwickelt. Zu Studienbeginn nutzten 33 % der Patient/-innen der Interventionsgruppe (IG) und 39 % der Kontrollgruppe (KG) HM. Nach sechs Monaten waren es 47 % (IG) und 35 % (KG). Zentrale Beweggründe scheinen die Stärkung der Selbstwirksamkeit, das Gefühl der Selbstbestimmtheit im Umgang mit der eigenen Gesundheit und die Vermeidung von Medikamenten zu sein. Diskussion und Schlussfolgerung: Die Ergebnisse können dazu beitragen die Ressource HM besser in die Therapieentscheidung bei älteren Patient/-innen einzubeziehen. Die Beratung zu HM in der hausärztlichen Praxis könnte eine niederschwellige Maßnahme zur gezielten Stärkung der Selbstwirksamkeit und Lebensqualität von älteren Patient/-innen sein.

To cope with the global climate crisis and assist in achieving the carbon neutrality, the use of biomass materials to fully or partially replace petroleum-based products and unrenewable resources is expected to become a widespread solution. Based on the analysis of the existing literature, this paper firstly classified biomass materials with potential application prospects in pavement engineering according to their application and summarized their respective preparation methods and characteristics. The pavement performance of asphalt mixtures with biomass materials was analyzed and summarized, and the economic and environmental benefits of bio-asphalt binder were evaluated. The analysis shows that pavement biomass materials with potential for practical appli-cation can be divided into three categories: bio-oil, bio-fiber, and bio-filler. Adding bio-oil to modify or extend the virgin asphalt binder can mostly improve the low temperature performance of asphalt binder. Adding styrene-butadienestyrene (SBS) or other preferable bio-components for composite modification will have a further improved effect. Most of the asphalt mixtures prepared by using bio-oil modified asphalt binders have improved the low temperature crack resistance and fatigue resistance of asphalt mixtures, but the high tem-perature stability and moisture resistance may decrease. As a rejuvenator, most bio-oils can restore the high and low temperature performance of aged asphalt and recycled asphalt mixture, and improve fatigue resistance. Adding bio-fiber could significantly improve the high temperature stability, low temperature crack resistance and moisture resistance of asphalt mixtures. Biochar as a bio-filler can slow down the asphalt aging process and some other bio-fillers can improve the high temperature stability and fatigue resistance of asphalt binders. Through calculation, it is found that the cost performance of bio-asphalt has the ability to surpass conventional asphalt and has economic benefits. The use of biomass materials for pavements not only reduces pollutants, but also reduces the dependence on petroleum-based products. It has significant environmental benefits and development potential.

Recently, environmental concerns have become a primary driving force in most countries and industries dealing with natural resources. As a part of this category, asphalt pavement industry is trying to implement more green and sustainable features in its products, while maintaining the mechanical and performance-based properties of the resulting asphalt mixtures. Among potential recycled materials, vehicle tires and aged asphalt pavement have been demonstrated to show economic, ecological, and behavioral improvements in the mixtures. However, mixtures with a high content of reclaimed asphalt (RA) and crumb rubber present some limitations. Therefore, using another group of additives, i.e., a warm mix asphalt (WMA) additive, has been considered. The presented paper investigates the use of an elevated content of RA with different crumb rubber modified binders and (in some mixtures) a warm mix additive in an asphalt concrete (AC) binder mix. Regular empirical tests have been conducted and more advanced performance or functional characteristics, i.e., stiffness, thermal induced cracking, resistance to permanent deformation, complex modulus have been determined and evaluated. Selected results are presented in the paper.

Since the internet has gained importance as a business platform, the world has seen an influx of ideas and new online tools. Internet as well as digitalisation have significantly altered the business landscape in many industries. One of the new tools that has been entering the market for several years now is the chatbot. The possibilities of chatbot technology are already quite well recognised in terms of its use as a service bot that answers simple recurring questions. However, for shopper marketing it is still a very new and hardly explored technology. The aim of this bachelor thesis is to assess the possibilities of chatbot technology in online shopper marketing. The fashion industry has been chosen as the target market for this research. For this purpose, an insight into the fashion industry is first given. In the course of this, it will be explained why online shopper marketing has gained such an importance for the fashion industry in recent years, as well as what activities are included in it. In this context the chatbot solution will be introduced. It will be dealt with the question how to maximise the utilisation of chatbot technology in order to improve online shopper marketing. In the course of this work, a survey will be conducted to clarify the acceptance of Germans towards chatbot technology as well as desired chatbot characteristics. The conclusion will provide guidance on how a chatbot should look like in the German fashion market and can be used by companies as a reference for the implementation of chatbot technology.

In the framework of this study, compressed earth blocks (CEB) were produced using waste materials and various parameters. Material parameters included waste soil, recycled concrete, fly ash, cement, admixtures and water contents. Manufacturing parameters were vibration during manufacturing, confinement pressure, curing environment and curing time. Specimens used in this study were cubes and compressive strength testing was used to evaluate different mixtures and manufacturing methods. In terms of compressive strength, compressed earth blocks made of these materials could be used for manufacturing bricks and other structural elements.

This paper presents a study about a Machine Learning approach for modeling the stiffness of different high-modulus asphalt concretes (HMAC) prepared in the laboratory with harder paving grades or polymer-modified bitumen which were designed with or without reclaimed asphalt (RA) content. Notably, the mixtures considered in this study are not part of purposeful experimentation in support of modeling, but practical solutions developed in actual mix design processes. Since Machine Learning models require a careful definition of the network hyperparameters, a Bayesian optimization process was used to identify the neural topology, as well as the transfer function, optimal for the type of modeling needed. By employing different performance metrics, it was possible to compare the optimal models obtained by diversifying the type of inputs. Using variables related to the mix composition, namely bitumen content, air voids, maximum and average bulk density, along with a categorical variable that distinguishes the bitumen type and RAP percentages, successful predictions of the Stiffness have been obtained, with a determination coefficient (R2) value equal to 0.9909. Nevertheless, the use of additional input, namely the Marshall stability or quotient, allows the Stiffness prediction to be further improved, with R2 values equal to 0.9938 or 0.9922, respectively. However, the cost and time involved in the Marshall test may not justify such a slight prediction improvement.

In this study a novel procedure is presented for an efficient development of predictive models of road pavement asphalt concretes mechanical characteristics and volumetric properties, using shallow artificial neural networks. The problems of properly assessing the actual generalization feature of a model and avoiding the effects induced by a fixed training-test data split are addressed. Since machine learning models require a careful definition of the network hyperparameters, a Bayesian approach is presented to set the optimal model configuration. The case study covered a set of 92 asphalt concrete specimens for thin wearing layers.

In recent years, the attention of many researchers in the field of pavement engineering has focused on the search for alternative fillers that could replace Portland cement and traditional limestone in the production of asphalt mixtures. In addition, from a Czech perspective, there was the need to determine the quality of asphalt mixtures prepared with selected fillers provided by different local quarries and suppliers. This paper discusses an experimental investigation and a machine learning modeling carried out by a decision tree CatBoost approach, based on experimentally determined volumetric and mechanical properties of fine-grained asphalt concretes prepared with selected quarry fillers used as an alternative to traditional limestone and Portland cement. Air voids content and stiffness modulus at 15 °C were predicted on the basis of seven input variables, including bulk density, a categorical variable distinguishing the aggregates’ quarry of origin, and five main filler-oxide contents determined by means of X-ray fluorescence spectrometry. All mixtures were prepared by fixing the filler content at 10% by mass, with a bitumen content of 6% (PG 160/220), and with roughly the same grading curve. Model predictive performance was evaluated in terms of six different evaluation metrics with Pearson correlation and coefficient of determination always higher than 0.96 and 0.92, respectively. Based on the results obtained, this study could represent a forward feasibility study on the mathematical prediction of the asphalt mixtures’ mechanical behavior on the basis of its filler mineralogical composition.

In this research study, selected fillers originating as stone dust or as back fillers have been used as potential substitutes to normally used limestone filler. They have been analyzed by XRF spectroscopy, density or quality of fine particles. These parameters might influence the effect of used fillers on asphalt mortar properties and mix performance. Two types of aggregates have been selected and alternative fillers have been added to asphalt mix of AC8 type according to modified procedure described by the standard EN 1744-4. For each asphalt mix containing alternative filler stiffness, Marshall stability and resistance to water immersion were determined to indicate the potentials of such substitution to asphalt mix durability and resistance to permanent deformation. From the results it is obvious that the chemical composition might have influence on the asphalt mix stiffness and the resistance to water immersion, similarly the physical properties of fillers will influence the asphalt mortar quality which is crucial for asphalt mix resistance to permanent deformation and moisture susceptibility.

The use of reclaimed asphalt has become a common practice and necessity in many developed countries whereas there are several options how to deal with elevated content of such material which is typical for some level of degradation and heterogeneity. Well-developed and widely used are solutions where reclaimed asphalt is cold fed by up to 20%. Higher portions of reclaimed asphalt are still challenging and need additional focus. Quite common in last few years is use of rejuvenators which are understood as special chemical compounds which help to partly restore the degraded bitumen and secure sufficient performance behavior of asphalt mix containing higher portions of reclaimed asphalt. Recent study focused on use of several market established rejuvenators and some newly developed variants which are predominantly based on renewable materials. A typical asphalt concrete AC16 has been selected and 50% natural aggregate was replaced by reclaimed asphalt of 0/8 mm grading. Rejuvenators were added in a content of 5–7% of the bitumen content presented in the reclaimed asphalt. Several tests have been performed focusing on water susceptibility, deformation behavior (stiffness) and resistance to crack propagation. At the same time bitumen extracted from the reclaimed asphalt was mixed with rejuvenator and selected bitumen tests were done to find some relation between binder and asphalt mix behavior.

In addition to bituminous binders (bituminous emulsion, foamed bitumen), hydraulic binders are applied in cold recycling technologies to increase the strength of a final structural layer as well as to increase its resistance to water and frost impacts. This paper deals with the use of energy by-products from fluidized bed coal combustion and mineral waste and their modification into reactive material with the potential of replacing commonly used hydraulic binders. The increase in the reactive potential takes place through a high-speed milling process where the mechanical-chemical activation of the material takes place. This process is associated with the refinement of the material, a higher proportion of micro and nanoparticles, an increased surface area, opening of particles, etc. The material treated exhibits binding properties, and it can be used as an active filler that allows for the partial or complete substitution of hydraulic binders. The experimental part is focused on the application of alternative binders to cold recycling mixtures and their assessment according to valid technical regulations, i.e., an assessment of their indirect tensile strength and water susceptibility as well as compressive strength and resistance to the effects of water and frost.

High modulus asphalt concrete (HMAC) presents a concept of an asphalt mixture with advanced performance which is suitable mainly for heavy loaded pavement structures. The mix concept was developed more than 25 years ago in France and became a standard in many countries. In the Czech Republic this type of asphalt mixtures is used since the early years of this millennium, when original technical requirements have been set. After almost 20 years a volunteer technical assessment started to validate whether the technical requirement set mainly for stiffness values and partly also for flexural strength or resistance to crack propagation are still up-to-date or if some reasonable modification is needed like was done several years ago in France when high modulus asphalt concrete of so called EME II or GP5 generation were brought to the practice. Based on this a study with focus on stiffness determination for more than 40 different HMACs was started. The stiffness was tested at different temperatures. At the same time virgin and aged asphalt mixtures were compared. Results from this study are presented by the paper.

The paper describes the situation in BIM implementation in public projects in the transport sector within global powers and the Czech Republic, emphasising the specificities of the construction market and legislation base in the Czech Republic. The specialised part presents the proposed methodology of BIM implementation in road construction, and demonstrates the different levels of detail and information using a BIM model. Last but not least, there is a risk analysis and the risks identified are briefly introduced.

Cold recycling techniques are known for decades in pavement engineering as a suitable rehabilitation method mainly for existing asphalt pavements. Traditionally the most common solution is to use bituminous emulsion or foamed bitumen as a binder usually in combination with small amount of cement or lime as active fillers. In some countries cement or hydraulic road binders are preferred instead of bitumen based options since it is believed that hydraulic binders can increase the bearing capacity of cold recycled layer especially for pavements with underestimated structures which were designed >40 years ago. Based on that the Faculty of Civil Engineering, CTU Prague is for more than 10 years evaluating and developing further alternatives for the cement-based approach of cold recycled mixtures. In the past experience with fly-ashes or activated fly-ash based alternative binders were presented. Presently the focus is concentrating on the potentials of using blast furnace slags which are not generally usable for the cement industry (e.g. because of limited content of glassy compounds which are very typical mainly for granulated blast furnace slags). Air-cooled blast furnace slags were selected and activated by high-speed milling to get a material with latent hydraulic properties. This modified slag was applied in several options to cold recycled mixtures and standard strength and deformation tests were performed, including the determination of resistance to water immersion. Separately pastes based on used treated fine-grained slags were tested and evaluated. Data of the pastes are discussed jointly with the results for experimentally tested cold recycled mixtures.

The paper presents the influence of laboratory aging simulation on fracture properties determined on 150 variants of asphalt mixtures. The fracture properties were determined by two different test approaches—semi-circular bending test (SCB test) and three-point bending test on beam specimens (3-PB test). The aging was simulated according to one of the methods defined in EN 12697-52 (storage of test specimens in chamber at temperature of 85 °C for 5 days). The evaluated group of variants covered asphalt mixtures for all road layers. The group was further divided according to used bituminous binder (unmodified vs. modified) and reclaimed asphalt content. The results showed that strength parameters (flexural strength and fracture toughness) increase with aging. It further shows that fracture work provides more complex information about the cracking behavior. For the aging indexes, it was found that for mixtures with modified binders and mixtures which did not contain reclaimed asphalt (RA), the values were higher. The aging indexes for fracture work showed different results for both performed tests.

In general terms, an artificial neural network is a distributed processor that consists of elementary computational units interconnected. Such structure is inspired by the functioning principles of the biological nervous system and has proven to be effective in identifying complex relationships between an assigned input features vector and an experimental- investigated target vector for any scientific problem. The current paper represents a forward feasibility study on predicting the mechanical response of asphalt concretes prepared with different quarry fillers used as alternatives for traditional limestone filler or portland cement by Machine Learning approaches which consider the chemical properties of the selected fillers and the quarry aggregate types as input variables. In fact, the case study involved several fillers and stone aggregates that were used to produce Marshall specimens of a specific fine-grained asphalt concretes designed originally for the assessment of filler suitability in terms of adhesion phenomenon. The asphalt concrete variants had the same material composition and mix design: all specimens were compacted by 2x50 blows using impact compactor, filler content was fixed at 10% by mass of the mix, the grading curve is roughly the same, the employed bitumen has a 160/220 penetration grade and is about 6% by mass of the mix. The mineralogical composition was investigated by X-ray fluorescence spectrophotometry tests. It represents a non-destructive laboratory analysis that allowed to specify and compare the main oxides composition associated with the employed natural fillers to be identified. Based on the results thus obtained and applying a categorical variable that distinguishes the stone aggregate type, a neural model has been developed that can predict the stiffness modulus of asphalt mixtures: therefore, this study presents a possible procedure for the development of predictive models that can help or improve the mix design process, when different fillers and stone aggregates are available.

Since the beginning of modern road construction, there have been effort to make durable, long life pavements. But no one pavement can fulfil designed purpose forever. On the other hand, some natural resources are limited, so it is important to maximize use of renewable resources. In recent years, there is a visible pursuit of this trend, in road construction represented mostly by use of waste materials, such as industrial by-products or recycled asphalt pavement itself. Within the effort, fibrous additives were established on the market to prolong life of pavement layers. Some commercial ones are synthetic polymer based, so it does not go well with the renewable part of pavement life cycle if we want to secure sustainable future. This paper describes use of fibres from natural renewable resource, specifically jute plant (Corchorus). Three asphalt mix variants with jute fibres were designed and further compared. Fibre content was 0.1 %, 0.2 % and 0.3 % by weight. Several tests were conducted to examine the effect of fibres on mixture properties, with aim on stiffness modulus (IT-CY) and crack propagation (SCB). Furthermore, indirect tensile strength ratio was calculated as a parameter showing performance of the mixture under the wet conditions. Control mixtures with paving grade and polymer modified bitumen were tested for better comparison and evaluation of the results.

The lifetime cost and environmental footprint of asphalt pavements hugely depend on their durability. It is widely accepted that water action plays a crucial role in the deterioration of hot mix asphalt concretes. Researchers seek solutions for promoting adhesion between bituminous binders and aggregate to avoid debonding (stripping) due to the presence of water and mechanical loading. In this research study, five different adhesion promoters were studied at multiple scales. The impacts on bituminous binders, their interactions with water and aggregates, and macroscopic properties of a selected type of asphalt concrete were assessed using both custom and standardized experimental test methods. The study revealed that the performance of additives cannot be assessed based on the results of a single test. A correlation was found between bituminous binder adhesion to aggregates, fracture-mechanical properties of asphalt concretes, and their susceptibility to deterioration in mechanical properties. The results indicate that silane-based adhesion promoter holds the biggest promise for increasing the resistance to stripping in asphalt concrete pavements.

Molecular dynamics is used to simulate the self-healing process of asphalts mixed with a healing agent. Sulfoxide functional groups were introduced into the virgin asphalt to produce a short-term-aged asphalt model. The model is validated by comparing density, diffusion coefficient, solubility parameter, and viscosity with real measurements. Plant oil and Aromatic oil are chosen as typical healing agents. The molecular models of asphalt and healing agent are integrated into a micro-crack model, and the healing process is simulated with molecular dynamics. The results show that Plant oil is a better choice for improving the healing rate of virgin asphalt, while Aromatic oil is better for improving the healing rate of short-term aged asphalt. The higher the temperature is, the better effect the healing agent will have on the asphalt. Healing is maximized above 15 degrees C for virgin asphalt and above 45 degrees C for short-term-aged asphalt. Molecular simulations show that the healing process depends on the diffusion of the healing agent and asphalt into the micro-crack. After the crack is filled, bitumen and oil molecules continue to mix. Aromatic oil produces a better mixing that leads to a more uniform composition and better mechanical properties. (c) 2021 Elsevier Ltd. All rights reserved.

Sleep is important for the development of preterm infants. During sleep, neural connections are formed and the development of brain regions is triggered. In general, various rudimentary sleep states can be identified in the preterm infant, namely active sleep (AS), quiet sleep (QS) and intermediate sleep (IS). As the infant develops, sleep states change in length and organization, with these changes as important indicators of brain development. As a result, several methods have been deployed to distinguish between the different preterm infant sleep states, among which polysomnography (PSG) is the most frequently used. However, this method is limited by the use of adhesive electrodes or patches that are attached to the body by numerous cables that can disturb sleep. Given the importance of sleep, this review explores more unobtrusive methods that can identify sleep states without disturbing the infant. To this end, after a brief introduction to preterm sleep states, an analysis of the physiological characteristics associated with the different sleep states is provided and various methods of measuring these physiological characteristics are explored. Finally, the advantages and disadvantages of each of these methods are evaluated and recommendations for neonatal sleep monitoring proposed.

This paper presents an experimental verification of the alternative options for using by-products or mineral waste materials applied to cold recycled mixtures with low level of stabilisation intended for low-volume road structures. To achieve the necessary refinement and a certain level of reactivity potential, the by-products were activated mechanically, i.e. pulverized in a high-speed disintegrator with respect to the lowest possible energy demands of the process and to the level of wear-and-tear of the working components in the milling machine. Such refined material, with average particle size of 10-15 μm, is applies as an active filler component allowing to partly substitute hydraulic binder in cold recycled mixtures. The application of such materials in structural pavement layers should increase the environmental benefits and result in added economic value. The experimental measurements taken focused on cold recycled mixtures with low level of stabilisation, modified by a combination of binders, or namely cement, mechanically activated concrete from reclaimed concrete pavement slabs originating from the Czech backbone D1 highway modernisation, mechanical-chemically activated fluid ashes from the Pilsen heat plant and foamed bitumen. Both basic volumetric properties and strength and deformation parameters were set for the purposes of evaluation of the characteristic measured in the experimental mixes.

Deterioration of asphalt pavements by water immersion and increased moisture content, presents one of the principal issues for pavement technologists. Especially if concentrating on initial phases of the life-cycle of a pavement. Water in the form of rain precipitation and natural air moisture can be harmful to the bonds between bitumen and aggregate particles, which occurs through the medium deteriorated adhesion on the interface of those phases, or the overall deterioration of the adhesion. Even if it might look at the first glance that bituminous binder creates perfectly impermeable layer of particular aggregate particles, in reality the bitumen film makes unstable coating of aggregates in unequal thicknesses and frequencies. Those weakened areas are far more susceptible to water and moisture affects, which enter the asphalt layer on the boundary of aggregates and bituminous binder. To improve the adhesion between bitumen and aggregates and to get in general better functional characteristics of asphalt mixtures large number of available additives exists in civil engineering. First group can be defined as additives which are added directly to the bituminous binder and provides a kind of bitumen modification. Second group includes mineral additives, which may partially or completely replaced fine-grained particles, normally in the form of filler. In this article the objective was set to qualify effect of mechanically activated microfiller originating from limestone by-products or from recycled concrete as a substitute to fine-grained active filler in asphalt mixtures. The research targeted to utilize waste materials and to contribute to the reduction of overall negative impacts to the environment.

Knowing the relationship between the stiffness modulus and the empirical mechanical characteristics of asphalt concrete, road engineers may predict the expected results of costly laboratory tests and save both time and financial resources in the mix design phase. In fact, such a model would make it possible to assess a priori whether the stiffness of a specific mixture, characterised in the laboratory only by the common Marshall test, is suitable for the level of service required by the road pavement under analysis. In this study, 54 Marshall test specimens of high modulus asphalt concrete were prepared and tested in the laboratory to determine an empirical relationship between the stiffness modulus and Marshall stability by means of shallow artificial neural networks. Part out of these mixtures was characterised by different types of bitumen (20/30 or 50/70 penetration grade) and percentages of used reclaimed asphalt (RAP at 20% or 30%); a polymer modified bitumen was used in the preparation of the remaining Marshall test specimens, which do not contain RAP. For the complex and laborious identification of the neural model hyperparameters, which define its architecture and algorithmic functioning, the Bayesian optimization approach has been adopted. Although the results of this methodology depend on the predefined hyperparameters variability ranges, it allows an unbiased definition of the optimal neural model characteristics to be performed by minimizing (or maximizing) a loss function. In this study, the mean square error on 5 validation folds was used as a loss function, in order to avoid a poor performance evaluation due to the small number of samples. In addition, 3 different neural training algorithms were applied to compare results and convergence times. The procedure presented in this study is a valuable guide for the development of predictive models of asphalt concretes’ behaviour, even for different types of bitumen and aggregates considered here.

The use of rubber powders in rubber concrete mixtures are gaining importance. In this study, the effect of the modified rubbers on the surface characteristics of rubber concrete is investigated, together with their engineering practicability by different rubber modification methods. The surface changes of rubber modified by sodium hydroxide, sulfonation, and urea were studied by contact angle and infrared spectroscopy. The basic mechanical properties and impact resistance of modified rubber concrete were studied and related by Scanning Electron Microscope image analysis. The results show that the selected rubber modification can improve the interaction between cement paste and rubber and improve the adhesion between them. Compared with ordinary rubber concrete, the compressive strength of rubber concrete treated with sodium hydroxide was only slightly improved, but its flexural strength, tensile splitting strength, and impact resistance were greatly improved. After the rubber was modified by urea or sulfonation, a variety of polar groups were introduced on the rubber surface. That led to an increase in the mutual attraction between rubber particles and cement paste, and improved the compressive strength, the tensile splitting strength, the flexural strength, and the impact resistance of rubber concrete. Furthermore, the strength loss of rubber concrete was greatly reduced. Rubber modification improves the performance of rubber concrete, showing good application potential.

High-modulus asphalt concrete is a specific type of asphalt mixture which is used for several decades in pavement engineering. It was originally invented as a solution which should help to minimize the effects of permanent deformation caused mainly by heavy traffic and mainly during the periods with elevated temperatures. These mixtures are used either in binder or base courses, whereas for base courses, it is important to combine reasonably the high stiffness with good fatigue life to avoid premature pavement failures not caused by rutting but by fatigue cracking. In this respect, various types of HMAC used and designed in the Czech Republic were tested first and foremost to determine stiffness. The stiffness modules were tested according to EN 12607-26, test method IT-CY, at selected temperatures representing cold, moderate and high service temperatures. The susceptibility to temperature change can be shown by thermal susceptibility for each mixture. In the parallel test, specimens were laboratory age to identify the changes in stiffness caused by thermo-oxidative ageing. This allows calculating a simple measure of the ageing index. Not presented in this paper but performed as a very last test was resistance to crack propagation.

The molecular model of asphalt binder was established by means of molecular dynamics (MD). The MD model was validated with respect of density, glass transition temperature, viscosity and solubility parameters. An interface system was created by inserting a vacuum pad of 50 A between 2 groups of asphalt binders to study the self-healing behavior of the asphalt binder, e.g. internal volume, diffusion rate of each component and energy variation of the model. The molecular diffusion of aged asphalt binder, SBS modified asphalt binder, and virgin asphalt binder are studied. The results show that the “compression” of asphalt binder volume and the “stretching” of the asphalt binder molecules is responsible for the disappearance of vacuum micro-cracks inside the asphalt binder. When the model volume is “compressed”, the volume of the asphalt model decreases until the micro-cracks in the asphalt binder disappear completely. The molecular volume of asphalt decreases greatly at the beginning of the MD simulation, and then becomes stable. The length of asphalt model increases in the OZ direction, while the length of the OX and OY directions decreases, indicating that asphalt “stretces” during the self-healing process. During the self-healing process, the diffusion coefficient of asphaltene molecule is the lowest, while the diffusion coefficient of the saturates is the highest at 360 K, aromatics and resins are close to the average value 6.227 × 10−4 cm2/s in the MD model. Self-healing is mainly based on the Van der Waals forces between non-bonded molecules. The aging of asphalt molecules reduces the diffusion rate of the asphalt model, and the SBS additive indirectly enhances the diffusion rate of asphalt.

As a developing nation that moves towards the sustainability, initiatives had been taken to address the solid waste disposal problem by incorporating them into asphalt pavement construction. This study integrates the recycled material named Recycled Paper Mill Sludge (RPMS) into the production of asphalt mixture as modifier through the partial substitution of mineral filler. The usage of solid waste material in pavement construction could substantially reduce the waste production and reduces the possibility of those waste materials ending up on landfills. This paper evaluates the microscopic analysis such as XRD, XRF and the mechanical properties of asphalt mixture with the incorporation of Recycled Paper Mill Sludge (RPMS). Mechanical properties that were evaluated were indirect tensile strength (ITS), moisture sensitivity, resilient modulus, Leutner shear and dynamic creep. RPMS was added to the asphalt mixture through dry process at the rate of 0.5% and 1%. Addition of RPMS at specific rate improved the mechanical properties such as resilient modulus, Leutner shear and dynamic creep of asphalt mixture. The lapped antenna like fibre of RPMS improved the resilient modulus of asphalt mixture by acting as a reinforcing material. Furthermore, RPMS contains calcite compounds that promote the adhesion bonding between asphalt binder and aggregates which significantly improved the performance in Leutner shear test and dynamic creep test.

The ever-increasing requirements on quality and life-span of asphalt layers present a reasonable motivation to explore new approaches and technologies. For many years, the technical options have included modification of regular paving grade bituminous binders. This paper focuses on the possible use of bituminous binders used; both activated and chemically improved by selected modifiers, in mastic asphalt as well as on their potential beneficial effects on selected parameters of the mixtures tested. The modification of reference paving grade bitumen 20/30 involved micromilled (pulverized) recycled crumb rubber as well as a new generation of synthetic waxes or even combination of the two types of additives. Potential benefit can be seen in the improved deformation characteristics and in the possibility to reduce the manufacturing temperature including potential improvements in mix workability. The paper presents the experimental assessment in the form of the indentation test, compression strength test, 3-point bending beam strength test, stiffness and creep characteristics. The properties of mastic asphalt mixtures are complemented by parameters of the bituminous binders applied (complex modulus, viscosity etc.).

The usage of certain amount of reclaimed asphalt (RA) is a well-established trend, which can be seen in many developed countries. Regrettably there are some countries or regions which still have very strict standard restrictions about RA usage in asphalt mixtures, mainly in surface layers. For example in current technical standards in the Czech Republic the use of RA in stone mastic asphalt mixtures or asphalt concrete for premium surface layers is banned. Recycling of construction materials saves direct primary costs like new material purchasing and at the same time also facilitates savings of other costs like energy, material disposal and transport etc. Those factors are connected to environment-friendly approaches, primarily in the case of emission and greenhouse gas production reduction. Material disposal can subsequently be reduced solely to waste or by-product materials which have no way of further utilization.

In developed countries there is a clear shift from new pavement structures to rehabilitation works which usually use the mill and fill method by replacing some of the asphalt layers. This process on one hand creates material which has to be milled and on the other hand requires new material for producing asphalt mixtures which are used back to the pavement structure. To improve the economic efficiency and reduce environmental impacts reuse or recycling are presently supported in elevated extent. To make the highest possible use of reclaimed asphalt rejuvenation is seen as one of the options. On the other hand excessive heating of reclaimed asphalt should be avoided to not overburn the bitumen or even to avoid additional ageing of already aged material. Combining effects of rejuvenation and warm mix technologies seems as an interesting option. In this respect a trial section was designed including 13 different options of warm mix asphalt with 0–50% reclaimed asphalt. The asphalt mixtures differed in amount of used reclaimed asphalt (RA) 0/11 mm (0%, 30% and 50%), the gradation of used paving grade bitumen (50/70,70/100) and warm mix asphalt additives or used techniques. In asphalt mixtures there were used bituminous binders with selected low temperature additive, which have primarily the function of reducing the production temperature, or the benefit in terms of improving the properties of the asphalt mixture, the adhesion improvement (in some cases) and in at least one of the cases the potential for reducing the characteristic odor of asphalt mixtures. Additives based on organo-silanes and different types of synthetic waxes (FT paraffin, amide wax, PE wax) have been used. Additionally foamed bitumen technology was applied as well. The asphalt mix performance was assessed by term of stiffness, resistance to permanent deformation, water susceptibility and thermal induced as well as fatigue cracking. The key findings will be presented by the paper.

Utilization of a high percentage of reclaimed asphalt pavement (RAP) requires higher production temperatures and consumes more energy. High production temperature expedites the aging of bitumen in RAP, which could affect the mixture performance. Warm mix asphalt (WMA) additive enables reduced production temperatures as a result of viscosity reduction. This paper evaluates the integration of a high percentage of RAP with a WMA additive known as RH-WMA. The optimum dosage of RH-WMA was determined from basic properties tests. A total of 0%, 30% and 50% RAP contents from two roads sources were modified with RH-WMA. The modified RAP bitumen were examined for viscosity, stiffness, rutting resistance and greenhouse gas emissions. The addition of RH-WMA improved the flow of bitumen by reducing the viscosity, and thus, decreased the construction temperature. The stiffness of the RAP modified bitumen reduced with the incorporation of RH-WMA. The positive improvement in rutting resistance was observed on bitumen with the addition of RAP and RH-WMA in comparison with control. It was estimated that the addition of RH-WMA could potentially reduce fuel usage and GHG emissions by 22 %. Hence, the synergy of RAP and WMA technology can be an alternative in green road construction.