Production Of Asphalt Mixtures Research Articles

GMA material design and construction quality control for asphalt pavement of steel box girder: Case study of the Hong Kong–Zhuhai–Macau Bridge

To improve the quality of the Hong Kong–Zhuhai–Macao Bridge paving project, a new paving layer material, Guss-mastic asphalt (GMA), was proposed in this paper by combining the advantages of two types of cast asphalt mixtures: mastic asphalt (MA) and Guss asphalt (GA). Based on the characteristics of GMA, to simulate its actual production process, this study developed a small-simulated cooker mixing equipment. Moreover, the flow degree, 60 ​°C dynamic stability, and impact toughness were proposed to be used to evaluate the construction and ease, high temperature stability, and fatigue resistance of GMA cast asphalt mixtures, respectively. Moreover, the quality control standards for GMA paving materials by indoor tests, field trial mix GMA material performance tests, and accelerated loading tests were finalized. The study showed that the developed simulated cooker yielded consistent mixing results in the same working environment as the engineering cooker device. Increasing the coarse aggregate incorporation rate, coarsening the mastic epure (ME) gradation composition, and using a smaller oil to stone ratio can reduce the flowability of the GMA materials to varying degrees. The four-point bending fatigue life and impact toughness of the different GMA materials are correlated well. A mobility of <20 ​s, 60 ​°C dynamic stability of 400–800 ​times/mm, 15 ​°C impact toughness of ≥400 ​N·mm, and cooker car mixing temperature control standard of 210 ​°C–230 ​°C form an appropriate control index system for the design and production of GMA cast asphalt mixtures. Simultaneously, accelerated loading tests verified the accuracy and reliability of the quality control index system that has been used in the GMA paving project of the Hong Kong–Zhuhai–Macao Bridge deck and has achieved good application results.

Detection of Reclaimed Asphalt Pavement Presence in Asphalt Mixtures Using a Method of Successive Asphalt Binder Extraction

The work deals with the detection of presence of RAP (reclaimed asphalt pavement) in asphalt mixtures. Information about the presence of RAP in an asphalt layer can be technically advantageous, for example, when planning further recycling of the layer. The method described in the paper can also be used to verify the success of a treatment of an aged binder in RAP, which is dosed in the production of new asphalt mixtures. The asphalt binder was obtained by a method of successive extraction from asphalt mixtures with different RAP content. Basic empirical tests of the asphalt binder (needle penetration and softening point) were chosen to detect the presence of RAP. The complex shear modulus G* was further determined on the extracted binders using a dynamic shear rheometer (DSR).

Laboratory simulation and mechanical performance of asphalt materials under the action of saline

Conventional asphalt mixture performs well in most asphalt pavement applications. However, blistering, which is a common phenomenon in semi-arid areas, is one distress mechanism caused by various detrimental salts resulting in the loss of adhesion at the interface of aggregates and bitumen. When moisture reaches this delaminated interface, it can lead to blistering under the action of heat and thermal expansion. There is heightened interest in the semi-arid areas to modify bitumen and enhance the mechanical properties of asphalt mixtures to address durability and cost-effectiveness issues. One of the approaches being investigated includes using renewable additives to promote a more environmentally friendly production of asphalt mixtures. In this study, two bitumens of penetration grades 40/60 and 50/70 were modified with various percentages of Teak (TK) fibre contents to prolong the service life of asphalt pavements in the semi-arid areas. The properties, including rheological information of base and TK fibre-modified bitumens, were obtained through rutting, penetration, thermal conductivity, and multiple stress creep recovery (MSCR) tests. Base and TK fibre-modified bitumens were soaked in different sodium hydrogen carbonate (NaHCO3) solution concentrations for varying durations. The MSCR test was used to investigate the mechanical performance of the bitumen and binder mastics under salt action. TK fibre modified bitumens demonstrated better rutting resistance, reduced penetration and lower thermal conductivity. The test results indicated that all binder mastics with TK fibres had reduced shear strain, higher recovery, and higher non-recoverable creep compliance than the base bitumen. The TK fibre-modified binders showed better resistance to the action of salt than the base bitumen but exhibited an increase in shear strain, reduction in recovery and increase in non-recoverable creep compliance for soaked samples with increasing salt content. Both base bitumens exhibited excessive softening and showed negative recovery at stress levels from 0.5 kPa with increased soaking duration and salt content. These results show that the optimum level of TK fibres was 2% by weight of bitumen. The results from this study are encouraging for the potential use of TK fibres to improve the performance of asphalt mixtures in semi-arid field conditions where the presence of salt, and specifically NaHCO3, is expected.

The Correlation between the Number of Asphalt Mixing Plants and the Production of Asphalt Mixtures in European Countries and the Baltic States

The transport infrastructure’s pavement is made of asphalt layers, placed and compacted. The asphalt mixture is produced in an asphalt mixing plant (AMP) using expensive technological equipment which, when it becomes obsolete and worn out, is replaced with new equipment. One of the main problems related to the replacement process is that when it comes to purchasing new AMPs, the decision making involved is, in most cases, highly intuitive due to a lack of clearly defined criteria. In order to remedy this situation, this work presents an analysis of the correlation between the number of AMPs and the production of asphalt mixtures. Firstly, a correlation analysis was performed based on the European Asphalt Pavement Association (EAPA) data. Secondly, the current situation with the AMPs in European countries was analysed. Furthermore, a case study was performed and a system of nine criteria was created to identify why/when road construction companies operating in the Baltic States buy new AMPs. The weights of the criteria have been established by applying the Analytic Hierarchy Process (AHP) method. It was found that the most important criterion during the decision-making process for road construction companies is increased requirements for improving the quality of the asphalt mixture produced (criteria weight 25.0%). With a weight of 20.6%, the second vital criterion is the possibility of receiving support from European funds. The third criterion is the expectation of having a sizeable asphalt-paving site (weight 20.4%). The other six criteria are also significant, their weights varying between 1.6% and 13.5%. The industrial companies can use the obtained results for designing, producing and selling AMPs and adjusting strategic business plans.

ДОСЛІДЖЕННЯ ЗОЛИ-ВИНЕСЕННЯ ЕЛЕКТРОГЕНЕРУЮЧИХ ПІДПРИЄМСТВ З МЕТОЮ ЇЇ ВИКОРИСТАННЯ ЯК АЛЬТЕРНАТИВИ ВАПНЯКОВОМУ МІНЕРАЛЬНОМУ ПОРОШКУ ДЛЯ ВИРОБНИЦТВА АСФАЛЬТОБЕТОННИХ СУМІШЕЙ

Introduction. Asphalt mixtures are one of the most widely used materials in the construction of roads. For the production of these mixtures, mainly conditioned mineral materials are used — coarse aggregate, fine aggregate and filler, and bitumen is used as a binder. Problem statement. In Ukraine, the filler is mainly used material obtained by grinding the carbonate rocks, which is established in DSTU B V.2.7-119 and DSTU B V.2.7-121. At the same time, as a result of coal combustion, millions of tons of dusty waste are generated at power generating plants of Ukraine - fly ashes and ashes from the hydraulic mine dump. These materials are close by grading to the requirements for the filler in accordance with DSTU B V.2.7-121 and probably can be used for the production of asphalt mixtures. Purpose. Determination of the possibility of using the fly ashes for the production of asphalt mixtures. Materials and methods. Type B asphalt concrete and mineral fillers of different origins were used during the research. Results. Test results showed that the studied fly ashes can be used for the production of asphalt mixtures, because the complete replacement of limestone filler with fly ashes from the thermal power plants does not lead to the deterioration of asphalt mixtures properties.

FINANCIAL ASPECT OF THE USING THE ASPHALT GRANULATE IN MIXTURES DESIGNED FOR ROAD SUBSTRUCTURES

Asphalt granulate is a valuable building material suitable for the production of asphalt mixtures. Its use in modern road building is profitable not only for environmental reasons but also because of the economic aspect of saving natural aggregates and asphalt and saving road pavement construction costs. The purpose of the cost analyses was to determine the financial benefits resulting from using the asphalt granulate in asphalt mixtures. The cost calculations concerned the basic components of asphalt mixtures and the costs of constructing the pavement structure layer for which the mixtures had been intended. The analyses covered asphalt mixtures of asphalt concrete type AC 22P with different content of asphalt granulate purchased at different prices, intended for road pavement substructure layers loaded with traffic of KR3 and KR4 categories.

Characterization of quarry dusts and industrial by-products as potential substitutes for traditional fillers and their impact on water susceptibility of asphalt concrete

Mixing, paving, and compaction of hot asphalt mixtures results in the formation of a three-phase system in which aggregates are represented in different fractions including subsieve particles (<0.063 mm), referred to as filler material. Larger particles interlock and form a skeleton, while the bituminous binder bonds individual grains together. Two filler types are commonly used for the production of asphalt mixtures: (i) lime, hydrated lime, or portland cement and (ii) fine particles retained in the separation units of a mixing plant (known as back/back-house filler) or those separated during aggregate production in quarries (quarry dust). We investigated the impact of several quarry dusts or back fillers as well as of selected treated by-products such as blast furnace slag, finely ground waste gypsum boards, or recycled concrete, all potentially applicable as alternative fillers. Different approaches were adopted to characterize these fillers and assess their impact on the adhesion between bitumen and aggregate in the presence of water, stripping resistance, and effect on the stiffness of the asphalt mixture. The results indicate that the effect of blast furnace slag or recycled concrete is superior to some conventional fillers and that mixing quarry dusts with portland cement or talc is beneficial for rendering the originally hydrophilic dusts more hydrophobic.

Influence of ternary blended cementitious fillers in a cold mix asphalt mixture

The manufacture of conventional hot mix asphalt (HMA) for paving has a substantial environmental footprint, and the production of clean asphalt mixture with good engineering performance is critically important. The introduction of cementitious filler is a promising approach to achieve outstanding mechanical properties for cold mix asphalt (CMA) as a clean paving material. This study aims to develop a novel CMA formulation through the combination of ordinary Portland cement (OPC) with two industrial by-products: fly ash (FA) and ground-granulated blast furnace slag (GGBS), which could make CMA even cleaner. To achieve this objective, the effects of ternary blended cementitious fillers on the early-age strength, engineering performance, and microstructural properties of CMA are characterized through comprehensive laboratory tests. The experimental results indicated that the indirect tensile strength of CMA-B containing 2% OPC, 1% FA, and 1% GGBS is approximately 20% higher than that of the mixture with 2% OPC (CMA-2% OPC). The residual Marshall stability ratio of CMA-B was increased to about 95% and its dynamic stability was approximately 10 times that of CMA-2% OPC. Employing blended cementitious fillers in CMA facilitates the formation of hydration products with excellent stiffness, reduces the air voids, and enhances interface bonding between aggregate and asphalt matrix, and thus suitable for applications in road pavements subjected to harsh service conditions in terms of moisture and temperature.

The Influence of Mixing Conditions on the Macro-Scale Homogeneity of Asphalt Mixtures Blended with Reclaimed Asphalt Pavement (RAP).

The homogeneity of asphalt mixtures blended with reclaimed asphalt pavement (RAP) is affected by many factors. Due to the complicated compositions of recycled asphalt mixtures, the inhomogeneity issue might cause insufficient mechanical properties of asphalt mixtures, even though a design method was appropriately adopted. Therefore, it is of great significance to study the influence of mixing conditions on the homogeneity of asphalt mixtures blended with RAP materials. This study focused on the macro-scale homogeneity of produced asphalt mixtures. Specifically, asphalt mixtures incorporated with 40% RAP content were produced in a laboratory using different mixing times and mixing temperatures. A multi-direction indirect tensile stiffness modulus (ITSM) test was proposed to quantify the homogeneity of produced samples. In addition, the digital image processing (DIP) method was used to identify the distribution of aggregates and RAP binder. The results indicated that the influence of mixing time on the macro-homogeneity of asphalt mixtures indicated that a longer mixing time was favorable for the material dispersion. The influence of mixing temperature mainly rested on two perspectives. One was that the temperature variation induced the change of binder viscosity. The other was that the temperature influences the diffusion process between RAP binder and new bitumen, which further affected the mechanical performance of produced asphalt mixtures.

Overview of methods of application of waste car tires in the production of asphalt mixtures and the possibility of application in Montenegro

The use of waste car tires in the production of asphalt mixtures has been used successfully for over 50 years around the world, starting with the USA, Australia, South Africa, many European countries, and progress in this area can be found in the region, especially Hungary. The aim of this paper is to get familiar with the methods of application of waste car tires in the production of asphalt mixtures that are used in the world, introduction to the basic terms, equipment and machinery necessary for production, construction and testing of mixtures, and analysis of basic conditions for possible application in Montenegro.

Rheological, physicochemical, and microstructural properties of asphalt binder modified by fumed silica nanoparticles

Warm mix asphalt (WMA) is gaining increased attention in the asphalt paving industry as an eco-friendly and sustainable technology. WMA technologies are favorable in producing asphalt mixtures at temperatures 20–60 °C lower in comparison to conventional hot mix asphalt. This saves non-renewable fossil fuels, reduces energy consumption, and minimizes vapors and greenhouse gas emissions in the production, placement and conservation processes of asphalt mixtures. At the same time, this temperature reduction must not reduce the performance of asphalt pavements in-field. Low aging resistance, high moisture susceptibility, and low durability are generally seen as substantial drawbacks of WMA, which can lead to inferior pavement performance, and increased maintenance costs. This is partly due to the fact that low production temperature may increase the amount of water molecules trapped in the asphalt mixture. As a potential remedy, here we use fumed silica nanoparticles (FSN) have shown excellent potential in enhancing moisture and aging susceptibility of asphalt binders. In this study, asphalt binder modification by means of FSN was investigated, considering the effects of short-term and long-term aging on the rheological, thermal, and microstructural binder properties. This research paves the way for optimizing WMA by nanoparticles to present enhanced green asphalt technology.

Production of asphalt mixes with copper industry wastes: Use of copper slag as raw material replacement

Copper slag is a waste obtained from copper production and it has a limited use, being mainly accumulated in landfills on a massive scale. This material presents a high hardness and it has hydrophobic properties, so it can be used as aggregate replacement in the production of asphalt mixtures. However, each size of copper slag behaves differently when used in asphalt mixes, especially under changing conditions of moisture or temperature. Precisely these climatic factors directly affect the service life of asphalt pavements. In this research, semi-dense graded asphalt mixtures were produced with copper slag as replacement of aggregates, varying the particle sizes used in the range from 2.5 to 0.08 mm to determine the size of copper slag with the best performance. Indirect tensile strength tests were used to analyze samples subjected to different moisture and temperature conditions and ageing degrees. The results show that copper slag can be used as aggregate replacement in asphalt mixes when the proper size is selected. The strength of the asphalt mixture increased as the size of the copper slag increased, especially under variable moisture and ageing conditions. Superior behaviour compared to a reference mixture was obtained when replacing the size of aggregate No. 8 with copper slag, increasing its indirect tensile strength and retained strength, reducing its stiffness under all the ageing periods, and being equally effective at the different temperatures, which results in mixtures with improved durability and delayed cracking. Furthermore, it would help to reduce between 15 and 20% of the virgin aggregate needed to produce asphalt mixes and it would also allow reducing the accumulated volume of this waste, decreasing the environmental impact of both industries.

Functional and environmental impacts of the use of reclaimed asphalt pavement materials and of foamed asphalt

Environmental safety related to asphalt mixing plants has been a growing concern due to the high temperature of asphalt mixture production resulting in a lot of energy used and much air pollutants released. Asphalt mixtures with foamed bitumen and RAP can reduce this problem. This paper deals with their functional and environmental effects. In the paper, it was introduced that the hot mix asphalt mixtures bound by foamed bitumen and containing RAP materials provides a good workability, in comparison to “traditional” hot mix asphalt mixtures. However, producing foamed bitumen needs special technological steps before using it as asphalt binder. The use of RAP materials reduces environmental harm and construction costs, besides it preserves the limited resources of stone, sand and gravel.

Preparation and performance of microcapsules for asphalt pavements using interfacial polymerization

Microcapsules for asphalt pavement containing asphalt rejuvenator as the core material were prepared via interfacial polymerization using high-speed shearing. Isophorone di-isocyanate (IPDI) and distilled water were used as the reaction monomers of the oil and water phases, respectively. Polyvinyl alcohol (PVA) was used as an emulsifier. The preparation process was optimized based on the type and concentration of the emulsifier, shearing speed, shell-core ratio, and reaction temperature. The technical properties of the asphalt pavement microcapsules prepared via the optimal preparation process were evaluated by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), laser particle size analyzer, and Thermogravimetric analysis (TGA) from the aspects of micromorphology, particle size, shell thickness, and thermal stability. Results showed that PVA possesses satisfactory emulsifying and shell-forming properties, which made it a suitable emulsifier in the oil phase. The optimized conditions of the microcapsule preparation are as follows: the concentration of the emulsifier solution was 0.4%, the shearing speed was 5000 RPM, the shell-core ratio was 0.6, and the range of reaction temperature was 60–70 °C. The diameter of the optimal microcapsules was primarily distributed between 10 and 17 µm. Furthermore, the average particle size was 14.26 µm; the microcapsule shell thickness was relatively uniform (2–3 µm). The results of FT-IR and TGA demonstrated that the asphalt pavement microcapsules maintain good chemical and quality stability at high temperature, indicating that the microcapsules can withstand the high temperature during the asphalt-mixture production process. The results of salt tolerance test showed that microcapsules have certain salt tolerance. The mean elastic modulus and hardness of microcapsules were 466.86 MPa and 56.27 MPa, respectively obtained by nano indentation test.

The influence of characteristics of aggregates on performance of asphalt mixtures

Under the current conditions of road traffic growth, importance should be given to the use of construction products whose technical characteristics have to be tested and to comply with the regulations in force. In our country at present there is the European standard EN 13043:2003 regarding the conditions that natural and artificial aggregates must meet in order to be used in asphalt mixtures. As is well known, these conditions are presented in the form of categories of values to be set by the designer to result in an asphalt mix with certain characteristics. However, this standard does not contain a national annex with specifications on the aggregate categories depending on the type of asphalt mix correlated with the technical class / road / street technical category. The majority of beneficiaries that use aggregates in the production of asphalt mixtures have problems on the national market because there is no correlation between this standard and the national provisions in force, namely the AND 605/2016 (version in force on this date). This paper analyzes the conditions that the natural aggregates for the bituminous mixtures must have and correlates the performance of the aggregates with the performance of the asphalt mix.

Environmental potentials of asphalt mixtures fabricated with red mud and fly ash

Several studies evaluated the feasibility of using residues to compose asphalt mixtures. However, the demand for treatments are often neglected in determining the environmental impacts. This study aims to elucidate the decision-making process over the application of residues (e.g., red mud and fly ash) to produce asphalt mixtures. For comparison purposes, limestone and dolomite are used as reference fillers. The cradle-to-gate approach is applied within three scenarios. In the first scenario, the treatment of the residues is included in the modelling, the second excludes treatment, and the third scenario evaluates the environmental impacts of the residues deposited in landfills. To perform the analysis, indicators such as Global Warming Potential, Acidification, and Cumulative Energy Demand are applied. The results show that the treatment provided to the residues strongly influences the environmental impacts of the production of asphalt mixtures and may be crucial to define the feasibility of the residues application.

Дослідження властивостей пилуватих відходів з електрогенеруючих підприємств України

Introduction. Disposal of recycled materials is targeted at saving the natural resources and reducing the volume of wastes that have to be disposed of in special landfills. Disposal is encouraged by many countries of the European Union. A key element in promoting of wastes recycling is the «polluter pays» principle, which has been included in all Community directives regarding management of safe and hazardous wastes. In order to encourage recycling, many Member States have adopted specific environmental legislation, in particular, the wastes disposal tax.Problem statement. Today, in Ukraine the issue of utilization of industrial wastes has not been solved, that is why a considerable part of them are in the dumps and pose a great risk for the environment; and only a small part of them is utilized in the construction projects [1], although there exists the «State Target Economic Program for the Development of Public Roads of National Significance for 2018–2022» [2] and the Order of the Cabinet of Ministers of Ukraine [3] which regulate the use of local materials, including industrial waste during the construction of motor roads. At the same time, millions of tons of dusty wastes are being produced at the Ukrainian power plants as a result of coal combustion — fly ash and ash from a tailings dam.Purpose. Carrying out of research of ash from a tailings dam and a mixture of limestone material with the ash from the tailings dam on conformity with the requirements to fillers.Materials and methods. The ash from a tailings dam, a mixture of limestone material with the ash from a tailings dam and commercially produced limestone filler have been selected for the study.Results. The results of the research on establishing the possibility of using the dusty waste products from power generating plants for the production of asphalt mixtures are presented. Experimental studies have been performed to determine the physical and mechanical properties of the ash from the tailings dam with partial replacement by limestone material. The conformity of the studied materials to the requirements of national standards was determined.Conclusions. Studies for determination of grading, porosity, swelling and structuring ability showed that the tested ash does not meet the requirements of Table No.5 of DSTU B V.2.7-121 for porosity in the case of compaction of 40 MPa; a mixture 80:20 — for swelling of samples of the filler with bitumen; and the mixture 50:50 meets the established requirements by defined indicators. A significant swelling increase of the samples from the mixture of filler with bitumen may be the result of high content of clay impurities in the test materials.Keywords: industrial wastes, limestone material, ash, filler. physical and mechanical properties.

Evaluation the Physical Properties and Marshall Stability for Asphalt Modified with Waste Polypropylene and Nanosilica Powder

Recently, Nanotechnology was being widely accepted in many fields due to its unique properties in enhancing the characteristics of many different kinds of materials, including asphalt binder. On the other hand, the usage of polymer nanocomposites for the production of durable asphalt mixtures has steadily replaced the use of polymer-modified binders. This study investigates the influence of nanosilica particles (NS) on rheological properties and mixture performance of asphalt modified with 2% waste polypropylene polymer (WPP). IN laboratory work, NS/WPP composite modified asphalt samples have been produced by adding three different percentages of NS particles (0.5, 1, and 2%) by weight of binder and 2 % WPP to control asphalt (60-70) penetration grade using a mechanical mixer and a homogenizer shear mixer with shear rate 27000 rpm for 10 min at mixing temperature (165 ±5) °C. The physical tests and Marshall stability were used to evaluate the NS/WPP composite modified asphalt binder properties and mixtures performance characteristics. This study found that 2 % of NS particles decrease the temperature sensitivity of WPP modified asphalt by 13% due to improving the hardness of the NS/WPP composite modified binder. The results also showed that the Marshall stability values of NS/WPP composite modified asphalt mixtures improved by 34.2% and 9.71% at 2 % NS compared with the control and WPP modified asphalt mixtures respectively. This suggests that the composite NS/WPP composite has a noticeable effect on the performance of the flexible pavement, thus increase paving’s service life.

Extended aging performance of high RAP mixtures and the role of softening oils

ABSTRACT Recently, there is a growing interest in increasing content of reclaimed asphalt pavement (RAP) material in the production of Hot Mix Asphalt (HMA) pavements to further reduce material costs and to preserve non-renewable resources. This study aims to evaluate the long-term performance of high RAP mixtures containing various softening oils. Both petroleum-based and bio-based oils were applied in preparing the 30% RAP and 50% RAP mixtures. The mixtures were subjected to the short-term oven aging (4 h), long-term oven aging (8 h), and extended-term aging (16 h) in the laboratory. Their performance, including the rutting, fatigue cracking at intermediate temperature, and low temperature cracking, were measured and compared with the control mixtures. The results indicate that the softening oils in this study can be used to produce asphalt mixtures containing high percentages of RAP with similar performance to a virgin mixture utilising the same aggregates and mixture design. In addition, the results show that making decisions to compare, qualify, or otherwise accept mixtures using the short-term aging results alone can be very risky. It is clearly shown in this study that relative ranking of mixture performance can change based on the level of aging.

Study on carbon emission accounting of warm mix asphalt mixture

At present, the international community emphasizes reducing carbon emissions, and the national level includes carbon peaking and carbon neutralization as development goals. As a landmark material for energy conservation and emission reduction in road engineering, the research on carbon emission accounting needs to be further refined. Based on the introduction of the basic concept, development process and current situation of carbon emission accounting of warm mix asphalt mixture, this paper focuses on the most novel and recognized energy consumption accounting method and carbon emission calculation method at home and abroad. The research results of carbon emission accounting in the production, transportation and construction of warm mix asphalt mixture are introduced in detail. Finally, the research on carbon emission accounting of this material is evaluated at the present stage and prospected in the future.