Next Article in Journal
Compression Law and Settlement Calculation Method of Over-Wet Soil Based on Large Samples
Previous Article in Journal
A Synchronous Tuning Control System for Very Low Frequency Communication Based on Real-Time Impedance Detection
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Applied Sciences
Volume 14
Issue 22
10.3390/app142210246
applsci-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

A Review of Sustainability in Hot Asphalt Production: Greenhouse Gas Emissions and Energy Consumption

by
Yancheng Liu
1,2,*,
Zhengyi Liu
1,
Youwei Zhu
2 and
Haitao Zhang
1
1
School of Civil Engineering and Transportation, Northeast Forestry University, Harbin 150040, China
2
Longjian Road & Bridge Co., Ltd., Harbin 150040, China
*
Author to whom correspondence should be addressed.
Appl. Sci. 2024, 14(22), 10246; https://doi.org/10.3390/app142210246
Submission received: 9 September 2024 / Revised: 26 October 2024 / Accepted: 3 November 2024 / Published: 7 November 2024
(This article belongs to the Section Green Sustainable Science and Technology)
Browse Figures
Versions Notes

Abstract

:
This study conducted a thorough analysis of energy consumption and greenhouse gas (GHG) emissions in the production of hot mix asphalt. The primary sources of energy usage in asphalt mixes are the heating of aggregates, asphalt, and burners, with aggregate heating accounting for a remarkable 97% of the total energy consumption. The results indicate that low-temperature asphalt mixes offer significant benefits over conventional hot mix asphalt in terms of energy efficiency and GHG emissions, with reductions in carbon dioxide emissions ranging from 18% to 36% and energy savings between 15% and 87%. Additionally, the use of recycled asphalt pavement led to a 12% decrease in carbon dioxide emissions and a 15% reduction in energy consumption. The study further explored the effects of various fuel types on emissions, revealing that replacing fuel oil with natural gas can effectively diminish the carbon footprint of the production process. By optimizing production temperatures and selecting cleaner fuel alternatives, this research highlights the potential for considerable energy savings and emission reductions within the asphalt production sector. These strategies not only promote sustainable road construction practices but also play a vital role in environmental protection and climate change mitigation, advocating for the adoption of innovative technologies in asphalt pavement production.

1. Introduction

The increasing volume of vehicular traffic on highways inherently leads to heavier representative vehicles, thereby placing a growing burden on highway bridges. It is imperative to construct high-quality pavements that can accommodate the demands of increasingly heavy traffic. A roadway consists of four distinct layers: the road base, subgrade, intermediate layer, and pavement. The pavement primarily comprises cement concrete, asphalt concrete, asphalt-crushed stone, and gravel. The type and thickness of the pavement materials are determined based on the anticipated traffic density [1,2,3]. Asphalt concrete pavements represent approximately 90% of the global total, while cement concrete pavements account for around 10% [4]. Figure 1 illustrates the global production of asphalt mixtures [5,6].
Asphalt pavement is composed of asphalt, which is derived from petroleum, and bonded together with aggregate. This product offers numerous advantages, including reduced fuel consumption, low noise levels, excellent skid resistance, and minimal vehicle wear [7,8,9]. Moreover, it can be adapted to meet varying performances and environmental specifications. The production of asphalt concrete requires significant quantities of high-quality stone and petroleum asphalt, along with substantial amounts of diesel, heavy oil, and other fuels. Furthermore, the high-temperature production and construction processes result in the release of certain harmful gases [10,11,12]. The introduction of more stringent environmental regulations has led to the closure of numerous stone mines, thereby reducing the availability of high-quality stone. Additionally, the cost of road construction has risen considerably due to the increasing price of asphalt and the escalating expenses associated with road development. The rise in road mileage and density has led to a corresponding increase in environmental pollution. Consequently, there is a pressing need to reduce energy consumption and greenhouse gas emissions [13,14].
The production of asphalt mixtures necessitates a considerable input of heat, which is derived from non-renewable energy sources. A reduction in energy consumption will result in a concomitant decrease in carbon emissions. This is one of the principal objectives of energy conservation and emission reduction. It has been established that between 60% and 85% of carbon emissions generated during the construction phase originate from earthworks activities [15,16]. Thus, advancements in technology in this area are crucial for ensuring the sustainable development of road infrastructure.
Although existing studies have focused on the environmental impacts of asphalt mixtures, there is still a lack of systematic analysis regarding the various factors in the production process, particularly concerning the specific effects of different heating technologies and fuel types on energy consumption and carbon emissions. This paper aims to fill this research gap by thoroughly investigating how these factors influence the production efficiency and environmental sustainability of asphalt mixtures. The study analyzed the energy consumption and carbon emissions associated with asphalt mixture production, particularly in the context of hot mix asphalt production. Furthermore, the effects of aggregate moisture content, combustion type, and energy source on energy consumption and carbon emissions were evaluated. The energy consumption and carbon emissions of asphalt mixes were assessed for different heating technologies, green raw materials, and heating energy types. The primary objective of this study was to evaluate and analyze the main sources of energy consumption and greenhouse gas emissions in order to identify effective measures for reducing environmental impact. The specific goals were as follows: (i) assessing energy consumption: analyzing the energy demands of different asphalt mixture production technologies (such as hot mix and warm mix) to identify high-energy consumption stages; (ii) analyzing environmental impact: reviewing the resource utilization, emissions, and potential environmental impacts associated with the production of asphalt mixtures, and emphasizing the importance of effective management and technological innovation in achieving energy conservation and sustainable development; (iii) proposing improvement measures: investigating how to reduce carbon emissions through the enhancement of raw materials, heating technologies, and the use of clean energy sources (such as substituting natural gas for fuel oil), with the aim of identifying construction materials that minimize their impact on the human environment, thereby promoting human health and contributing to the green development of asphalt concrete. This research holds significant importance in the field of road engineering.
The following outlines the structure of this paper. Section 2 introduces the research approach and methods employed in this study. Section 3 provides foundational knowledge on road types, emphasizing the importance of assessing the energy consumption and greenhouse gas emissions associated with asphalt road surfaces. Next, Section 4 clarifies the impact of temperature on the energy consumption and gas emissions of asphalt mixtures. In Section 5, a detailed overview of the energy requirements and gas emissions during the different production processes of asphalt mixtures is presented. Section 6 reviews the energy consumption of asphalt and highlights the necessity of implementing measures to reduce the carbon footprint for sustainable development. Subsequently, Section 7 discusses low-carbon green development of road asphalt from the perspectives of recycled materials (recycled asphalt, recycled shredded rubber, and biochar) and clean energy. Finally, Section 8 summarizes the main conclusions of this investigation and proposes recommendations for future research directions.

2. Methodology

This study employed a research methodology comprising three parts: (i) a comprehensive review of asphalt mixtures from the perspectives of energy consumption and gas emissions; (ii) an exploration of low-carbon development technologies; and (iii) the conclusions of this research.
First, we defined the research focus as the energy consumption and gas emissions of asphalt mixtures, categorizing it into five areas: pavement types, temperature effects, production processes, energy consumption, and low-carbon development. This framework ensures the relevance and systematic nature of the literature review. We systematically reviewed the existing literature using the Web of Science and Scopus databases, conducting an initial analysis of high-quality studies published between 2010 and 2024 related to the energy consumption and gas emissions of asphalt pavements. The keywords employed in the search included “energy consumption” + “asphalt”, “gas emissions” + “asphalt”, “energy consumption” + “pavement”, and “green development” + “asphalt”. This process was supplemented by manual searches. The selection strategy identified 103 high-quality articles (i.e., peer-reviewed indexed research articles). These works enabled the authors to critically examine the latest technologies to address the research questions. Ultimately, five sections were established to analyze and categorize the energy consumption and greenhouse gas emission characteristics of asphalt mixtures. Through a detailed analysis of each research aspect, key insights were derived, as outlined below:
  • Pavement types: analyzing the impact of different pavement types on energy consumption and emissions, highlighting their significance.
  • Temperature effects: investigating the influence of temperature on the performance and production efficiency of asphalt mixtures, noting the energy consumption and emissions issues associated with high-temperature production.
  • Production processes: providing a detailed description of the production process of asphalt mixtures, emphasizing the energy consumption and emission characteristics at each stage.
  • Energy consumption: evaluating the overall energy consumption of asphalt mixtures, identifying high-energy consumption segments, and exploring methods to reduce energy usage.
Additionally, we assessed green technologies and material recycling in the context of recycled materials and clean energy, focusing on their roles in reducing carbon emissions and achieving sustainable development. Finally, we distilled conclusions and recommendations that summarize the main findings across all aspects, emphasizing the importance of asphalt mixtures in environmental impact assessments and proposing future research directions that encourage the exploration of new technologies and materials (see also Figure 2).

3. Road Pavement Types

A road is defined as a layered structure comprising a range of road construction materials, laid on top of a road base layer for vehicular traffic. The functions of a road include the carriage of vehicle loads, the resistance of wheel friction, and the maintenance of continuity of the road surface. Accordingly, the pavement must possess elevated tensile strength, optimal structural stability, superior leveling, adequate anti-slip properties, and minimal dust generation during vehicle traversal [17,18,19,20]. The objective is to minimize damage to the pavement and vehicle components, ensure clear visibility, and reduce environmental pollution. The mechanical properties of the pavement determine its classification as rigid, flexible, or semi-rigid. The flexural strength of rigid pavements, such as those constructed from Portland cement concrete, is high due to the plate action that occurs under vehicle loads. In contrast, flexible pavements have low flexural strength and rely mainly on compressive and shear strengths to withstand vehicle loads. Repeated loads result in residual deformation, as is the case with asphalt and gravel pavements [21,22]. As an intermediate type between rigid and flexible pavements, semi-rigid pavements combine the advantages of both, exhibiting good flexural strength while its structural design allows it to withstand a certain degree of deformation. Semi-rigid pavements typically utilize cement-stabilized materials as a base layer, enhancing their load-bearing capacity and reducing the damage caused by repeated loading to some extent. Consequently, semi-rigid pavements provide more stable and durable performance under varying traffic conditions, making them a significant choice in modern road engineering [23,24,25].
As shown in Figure 3, the asphalt concrete pavement structure comprises multiple layers, including a hot mix asphalt surface layer, a pavement base, a sub-base, and a road base [26,27]. The surface layer serves as a structural component, providing resilience against repeated wheel loads and the effects of natural elements. It may consist of one to three sub-layers. In accordance with usage requirements, the surface layer should feature a non-slip, wear-resistant, dense, and stable asphalt layer. Hot mix asphalt is a combination of various aggregates and asphalt cement, created by heating asphalt to high temperatures. The grading of the particles used in the mix determines the classification of hot mix asphalt into four types: dense-graded, semi-open-graded, open-graded, and intermittent-graded. Rigid pavements are constructed using hydraulic cement concrete, which comprises cement (specifically Portland cement and supplementary cementitious materials such as fly ash and ground granulated blast furnace slag), sand, stone, water, and admixtures [28]. Unlike asphalt mixtures, Portland cement mixtures do not require the aggregates to be dried before mixing, as additional moisture can be incorporated into the mixture design [29]. Consequently, the energy consumed in the production of Portland cement mixes, aside from the energy required for the production of raw materials, is primarily utilized for the transportation of these materials, with a minor proportion allocated for the operation of the aggregate crushing plant. In contrast, the production and transportation of asphalt mixes necessitate an evaluation of energy consumption and greenhouse gas emissions. A significant number of researchers have investigated the high performance and durability of flexible pavements while emphasizing their implications for green sustainability. They have highlighted the importance of utilizing recycled or waste materials as aggregates or components wherever feasible, aiming to reduce oil consumption [8,30,31,32].

4. Effect of Temperature on Asphalt Mixtures

Asphalt mixtures are composite materials, commonly referred to as hot mix asphalt or conventional mix asphalt. These mixtures primarily consist of aggregates (both sand and coarse aggregates), fillers, and asphalt cement [33]. In some cases, additives such as binder mobilisers [34], modifiers [35,36] or fibers [37,38] are added to improve the product properties. Asphalt mixtures can be classified based on several criteria, including production temperature, mineral composition, and the incorporation of recycled materials. They are widely used in the construction and maintenance of highways, urban roads, airports, and parking lots. Figure 4 illustrates the categorization of hot mix asphalt according to its production temperature [39]. Cold mix asphalt is produced at temperatures below 60 °C, while semi-temperature mixing is typically conducted between 70 °C and 95 °C under conditions below 100 °C. Warm mix asphalt is produced at temperatures ranging from 110 °C to 140 °C, whereas hot mix asphalt is produced at temperatures between 150 °C and 170 °C [40].
It is common practice in hot mix asphalt production and paving operations to emit complex hydrocarbon aerosols, vapors, and gaseous mixtures consisting of combustion products, volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs) into the atmosphere [13,41,42,43]. This occurs during all phases of the production and paving process. The use of low-temperature blended asphalt represents a novel and sustainable technology that significantly decreases production and application temperatures. This approach encompasses a range of blended asphalts, including cold mix, semi-temperature mix, and warm mix asphalt. The innovative asphalt production plant effectively reduces harmful emissions and fumes, thereby improving working conditions for those employed at the plant, including operators and other personnel [44,45].
Autelitano et al. [46] discovered that incorporating organic waxes and other additives into warm mix asphalt mixtures utilized in road construction could potentially reduce the required production temperature by approximately 30 °C, thus minimizing asphalt emissions. This outcome is particularly significant when temperatures approach or exceed the melting point of waxes (110 °C). A 10 °C reduction in asphalt production temperature has been found to result in a 1 L reduction in fuel consumption and a 1 kg/ton reduction in equivalent CO2 emissions, according to data from the World Bank [47]. The use of warm mix asphalt mixtures enhances processability and extends transportation distances, with these benefits being in addition to those associated with lower production temperatures. Furthermore, the reduction in energy consumption that results from lower production temperatures impacts overall production costs [48,49].
Using reclaimed asphalt is another effective strategy for reducing energy consumption and pollutant emissions [50]. The term “Reclaimed Asphalt Pavement (RAP)” refers to the product of a pavement maintenance program or the full-depth demolition and rehabilitation of a pavement [51]. In recent years, RAP has been recognized as an important source of recycled material for pavement construction. Recycled asphalt mixes and aggregates are supplied to asphalt production plants for reuse. This practice has the dual benefit of reducing energy consumption in the production process and limiting the extraction of virgin aggregate and waste. Among the numerous RAP hybrid technologies, the parallel drum dryer has demonstrated superior environmental compatibility and energy efficiency, establishing it as a leading contender in this field. The primary factors influencing fuel consumption are the temperature and moisture content of the RAP mixture [52,53].

5. Asphalt Mixture Production

The primary function of an asphalt mixing plant is to produce substantial quantities of asphalt, which is then utilized in the construction of motorways, local roads, and other road projects. The principal components of an asphalt mixing plant include a batching system, which adjusts the proportion of raw materials to meet the specifications of the construction project; a drying system, which eliminates moisture from the raw materials; a vibrating screen, which pulverizes large particles of the raw materials; a weighing and mixing system, which ensures the accuracy of the production process; and a dust collection system, which minimizes the emission of pollutants during production. The categorization of mixing plants depends on their production capacity, with classifications including small, medium, and large; portable, semi-permanent, and permanent facilities [54].
Figure 5 illustrates the asphalt mixing process flow with emission sources. Prior to incorporation into the mixer, the asphalt mix mineral powder is stored, transported, de-dusted on two occasions, and metered with precision. Aggregates are moved from the warehouse to the drying room, where they are heated to a temperature range of 150–170 °C. They are then screened, stored, and accurately dosed before entering the mixing system. Following the melting, dewatering, and elevation of the asphalt to the requisite production standards, the material undergoes a heating process, is held at a constant temperature, and is measured with great precision. It is then introduced into the mixing system. The selection of suitable additives follows; these additives are stored, transported, and measured accurately before being added to the mixing system. The production team then initiates the mixing process, and once the internal composition of the mixing system has been verified, the final asphalt product is transported to the finished silo for use [55].
The fuel used for heating and drying materials in the production process is the primary source of emissions, accounting for 80% of total CO2 emissions, while electricity contributes the remaining 20%. The vast majority (97%) of thermal energy is utilized for heating and drying aggregates. Therefore, managing the moisture content of these aggregates is critical for energy conservation. At a moisture content of 4%, the energy required for drying aggregates increases by 60% [56]. Furthermore, the removal of 1% moisture from a mineral mixture necessitates an input of 7.34 kWh of thermal energy [33], as illustrated in Table 1.
The solar aggregate inventory method is employed to decrease moisture content [6]. The primary objective of designing solar energy storage systems is to harness high-quality thermal energy from solar radiation when mineral mixtures are exposed. Figure 6 presents an experiment conducted in Croatia to analyze the impact of varying sunlight on the thermal storage performance of mineral mixtures in solar aggregate silos across different seasons (summer and autumn). Three solar aggregate inventory test models, along with one reference model simulating uncovered and unprepared surface storage conditions, were constructed. It was observed that utilizing solar energy aggregate inventory can lead to the preheating of aggregates and a reduction in their moisture content. This approach has the potential to improve energy efficiency and thermal storage performance while addressing challenges associated with variable sunlight conditions throughout the seasons. Androjic et al. [39] discuss the potential energy savings and the ability to predict the temperature of aggregate piles to achieve sustainability using an artificial neural network (ANN) model. The modeling results indicate that the ANN can successfully predict the temperature of aggregate piles during production and storage as part of the entire asphalt mixture production process.

6. Asphalt Mixture Energy Consumption

All stages of road development, from construction to operation, result in the consumption of significant amounts of ecosystem goods and services, as well as the generation of waste and emissions. The energy consumption of asphalt in the manufacturing process primarily depends on diesel and electricity usage during the operation of the asphalt plant. The transportation of asphalt materials, plant operations, transportation of mixtures to the construction site, and placement on the road surface all rely on diesel fuel produced by refineries. Electricity is supplied by the generation and distribution sectors and is primarily consumed during the operation of hot mix asphalt mixing plants [54,61]. Generally, the two main stages of energy consumption during pavement construction are material production and construction. The most commonly used paving material is hot mix asphalt, which involves heating the aggregate and asphalt at high temperatures, resulting in substantial energy consumption. In many modified asphalt mixtures, the asphalt is continuously stirred and heated during the modification process. Higher temperatures not only significantly increase energy consumption but also lead to the release of smoke during mixing and laying [62]. A considerable amount of CO2, CH4, NO2, and other greenhouse gases are emitted concurrently with energy consumption. The carbon emission evaluation model can assess the carbon emission status of existing asphalt pavement construction, providing a quantitative description of current emissions. This model also serves as a reference for transforming asphalt pavement construction from a high-carbon emission mode to a low-carbon emission mode. The selection of carbon emission evaluation indicators is based on investigations and calculations at each stage, with the objective of accurately reflecting the project’s actual situation being the chosen index [63]. Peng et al. [42] introduced a calculation model for energy consumption emissions to break down carbon emissions into two components: energy consumption emissions in the pavement construction process and volatile emissions from the asphalt mixture itself. As shown in Figure 7a, their findings indicate that aggregate heating and asphalt heating are the primary sources of carbon emissions resulting from energy consumption, accounting for an astonishing 92.08% of total carbon emissions generated during this stage. Additionally, Figure 7b depicts that the rolling and spreading processes are the main sources of carbon emissions from asphalt mixture volatilization, accounting for a significant 98.53% of total emissions in this category. Hence, these two processes are identified as the primary sources of carbon emissions stemming from asphalt mixture volatilization. Cao et al. [64] established a quantitative model for greenhouse gas emissions during the construction of asphalt pavements for different energy types, and evaluated carbon emissions during the construction period. The results showed that the high-emission links during the construction of asphalt pavements were aggregate heating, asphalt heating, and asphalt mixture mixing, accounting for 64.66%, 14.63%, and 13.21% of the total energy consumption and greenhouse gas emissions, respectively. In summary, the construction of asphalt pavements necessitates substantial quantities of materials, technology, and fuel, leading to significant CO2 emissions. Given the pressing need to reduce these emissions, it is imperative to lower the carbon emission levels associated with asphalt pavements and to implement effective mitigation materials and technologies. Such measures will not only contribute to the achievement of sustainability goals but also mitigate the ecological impact of asphalt pavement construction and maintenance.

7. Low-Carbon Green Development of Asphalt Mixtures

Low-carbon and green development in asphalt pavement construction is a crucial aspect of alleviating the pressure on environmental resources. Global warming, primarily driven by greenhouse gases such as carbon dioxide, poses a critical environmental issue. It is essential to modify raw materials and implement emission reduction measures in heating technology, as well as to modify raw materials, heating energy types, and other aspects to reduce greenhouse gas emissions from energy consumption during the construction process [65]. In response to this challenge, many countries have committed to achieving net-zero emissions by 2050, with over 125 nations establishing long-term reduction targets that reflect a global commitment to addressing environmental change [66]. While traditional asphalt is widely used due to its durability and cost-effectiveness, its production and usage contribute to greenhouse gas emissions and biodiversity loss [2,67]. Consequently, the utilization of recycled waste and innovative materials, such as recycled materials, has become essential. These new materials not only reduce dependence on conventional materials but also provide viable solutions for achieving low-carbon emissions [59,68].
In light of the pressing need to reduce emissions, it is crucial to lower the carbon footprint of asphalt pavements. This not only aids in meeting sustainable development goals but also mitigates the ecological impact of construction and maintenance activities. Sustainable asphalt pavement practices offer significant advantages: the use of recycled materials can reduce greenhouse gas emissions, decrease maintenance costs over the long term, and enhance pavement durability [69,70]. The adoption of green low-carbon technologies, such as the utilization of recycled materials and the integration of clean energy sources, will further advance the sustainable development of asphalt pavements and contribute to the construction of more environmentally friendly transportation infrastructure.

7.1. Recycled Material

The application of recycled materials (such as recycled asphalt pavement, biochar, and crumb rubber) and advanced technologies in asphalt pavement can significantly reduce negative environmental impacts, including greenhouse gas emissions and the depletion of fossil fuel resources [49]. This approach also promotes effective waste management and decreases the need for dumping sites.

7.1.1. Recycled Asphalt

Reusing milling material from old asphalt pavement in the construction of new roads can significantly reduce waste disposal, which typically consumes land resources. This practice minimizes the need for mining new materials, conserves energy, and facilitates the recycling of materials.
The reutilization of milling material derived from old asphalt pavement offers numerous environmental benefits. It not only alleviates the land requirements associated with waste disposal but also reduces the need for extracting new materials. This approach conserves energy and promotes material recycling while minimizing overall environmental impact. Giani et al. [71] conducted a study analyzing the environmental benefits of using recycled asphalt pavement. Their research demonstrated that when recycled asphalt pavement (RAP) is mixed with new asphalt, it can decrease carbon emissions by up to 6.8%. Furthermore, the combination of RAP and warm mix asphalt (WMA) technology has resulted in a 12% reduction in CO2 emissions and a 15% decrease in energy consumption throughout the road’s life cycle. Gulotta et al. [72] also demonstrated the substantial benefits of combining recycled asphalt pavement (RAP) with warm mix asphalt (WMA) in mitigating CO2 emissions. This approach not only enhances the sustainability of asphalt mixtures but also contributes to the overall reduction in the carbon footprint associated with road construction and maintenance. Furthermore, Wang et al. [73] investigated the carbon emissions associated with the construction of foam asphalt cold-recycled pavement. Their findings revealed that when producing 1 ton of asphalt mixtures, the foam asphalt cold regeneration technology significantly curtails energy consumption, saving 28.984 kg of standard coal and resulting in a decrease of 71.206 kg in CO2 emissions. This is a remarkable 47.1% reduction compared to the emissions generated during the production of asphalt-stabilized gravel, highlighting the significant energy-saving benefits of this technology. Feng et al. conducted a comprehensive evaluation of the sustainability of recycled asphalt pavements (RAPs) from three key perspectives: cost, energy, and environmental impact. The study found that, particularly in the context of thin asphalt overlays, the use of RAP represents a more economically efficient and environmentally feasible alternative [74].
The combination of 100% recycled asphalt with crumb rubber and waste engine oil (WEO) is considered the most environmentally friendly type of asphalt. This mixture results in a 49% reduction in carbon dioxide (CO2) emissions, a 97% reduction in volatile organic compounds (VOCs), a 97% reduction in nitrogen oxides (NOx), a 22% reduction in methane (CH4), and a 39% reduction in sulfur dioxide (SO2) emissions. The production energy consumption of the R100-CRM-x-WEO mixture is 52% lower than that of the original mixture, with 99% of the materials derived from buried waste, significantly improving environmental quality [75]. Additionally, the use of recycled asphalt as a base layer can reduce phosphorus compound emissions in water by 45 g/m3, outperforming hot mix asphalt (HMA). In terms of ecotoxicity and human non-carcinogenic toxicity, the indicators for the CMRAJ mixture are 60% lower than those for HMA. The incorporation of recycled asphalt pavements (RAPs), non-conforming fly ash (OFA), and food waste bio-oil (FWBO) further reduces environmental impacts [76]. In summary, the introduction of sustainable asphalt mixtures and innovative material combinations not only effectively reduces the emissions of various pollutants but also promotes the widespread application of environmentally friendly asphalt, significantly enhancing the environmental benefits of road construction.

7.1.2. Recycled Shredded Rubber

Crumb rubber, a recycled material derived from discarded tires, has the potential to become a sustainable asphalt pavement when mixed with asphalt mix through both wet and dry processes. This innovative approach to waste material utilization offers a promising future for sustainable road construction. Tushar et al. [77] investigated the environmental impact of utilizing crumb rubber (CR) particles as a polymer additive to enhance asphalt performance. Their findings revealed that recycling waste tire rubber can significantly reduce carbon dioxide (CO2) emissions by 71.9% compared to landfilling or incineration. When adding 2% CR to the asphalt mixtures, the resulting reduction in carbon emissions is 23.20%. These findings emphasize the importance of recycling waste materials and the potential of sustainable asphalt pavements. Furthermore, Wang et al. [78] investigated the performance of crumb rubber-modified asphalt in 1-ton asphalt mixtures. As illustrated in Table 2, their findings revealed that this sustainable pavement material resulted in a reduction in carbon emissions ranging from 18% to 36%, while also achieving energy savings between 15% and 87%. These impressive figures demonstrate the significant environmental benefits of using recycled tire rubber in asphalt mixtures. Wang et al. [79] compared the performance of clastic rubber modified asphalt with SBS modified asphalt, specifically focusing on their respective energy-saving and emission reduction capabilities. The results of their study revealed that the detrital rubber modifier can significantly reduce energy consumption by 86.24–89.50% and CO2 emissions by 89.5%. This finding highlights the potential of using the CR modifier as a sustainable replacement for SBS modifier in asphalt mixtures. Moghimi et al. modified warm mix asphalt with different levels of crumb rubber (10%, 15%, and 20%) and demonstrated that 10% crumb rubber-modified asphalt exhibited optimal rutting, moisture sensitivity, and fatigue resistance, and a 22% increase in tensile strength ratio relative to the 10% specimen [80]. The reduction in emissions and optimization of performance can be primarily attributed to the balance between the physical properties of crumb rubber materials and their chemical interactions. On the one hand, the incorporation of crumb rubber enhances the elasticity and crack resistance of asphalt, thereby improving the durability and lifespan of the pavement. On the other hand, the characteristics of rubber contribute to the reduction in asphalt volatility at elevated temperatures, leading to decreased emissions of volatile organic compounds (VOCs) and other pollutants. Consequently, the synergistic effects of this material achieve a favorable balance between environmental benefits and performance enhancement. However, the scarcity of shredded rubber, an important renewable resource in the recycling of end-of-life vehicles, has become increasingly pronounced. This scarcity not only arises from the inherent limitations of the resource and the challenges associated with its recycling, but is also profoundly influenced by factors such as the recycling rates of old vehicles and variations in legislative frameworks across countries. Increasing the recycling rates of end-of-life vehicles can significantly increase the supply of shredded rubber. However, notable disparities in the legislation, technological capabilities, and policy incentives related to end-of-life vehicle recycling among different countries result in inconsistent recycling rates. Countries such as those in Europe have established relatively sophisticated recycling systems, implementing a series of effective policies and regulations to promote the recovery of waste tires [81]. In contrast, although China has the highest levels of rubber production and consumption, there are no standardized technical and quality criteria for the recycled products of waste rubber [82,83,84]. On the other hand, differences in the comprehensiveness of the legal frameworks for end-of-life vehicle recycling, the strength of policy incentives, and the robustness of regulatory enforcement across nations also directly affect the effective recovery and reuse of shredded rubber resources, thereby exacerbating their scarcity [85,86,87]. Therefore, addressing these challenges is crucial for maximizing the potential of crumb rubber in sustainable asphalt pavement applications and ensuring a stable supply of this valuable resource.

7.1.3. Biochar

In recent years, there has been an increasing focus within the pavement industry on reducing carbon footprints and providing new strategies to address climate change. Biochar, as a renewable resource, has garnered significant research interest due to its potential in soil enhancement and carbon sequestration. Biochar is a carbon-rich material produced through the pyrolysis of biomass, primarily derived from agricultural residues (such as rice husks and corn stalks), forestry waste (such as branches and bark), and food processing by-products (such as fruit pits and vegetable scraps) [88,89,90]. Researchers have explored the use of biochar as an additive in asphalt mixtures to reduce overall carbon emissions. Zhou et al. [91] found that the energy consumption of biochar-modified bioasphalt (BMBA) is only 25% of that of conventional asphalt, with energy savings of 25% and 38% during the production and preparation stages, respectively. The greenhouse gas (GHG) emissions reported in this study range from 0.16 to 0.19 kg CO2 equivalent per kg of BMBA. By partially substituting traditional mineral fillers with biochar, it is possible to effectively reduce the carbon intensity of materials while enhancing the performance and durability of asphalt. However, the production process of asphalt pavements inevitably releases volatile organic compounds (VOCs), posing health risks to construction workers [92]. To address this issue, some researchers have begun to investigate the application of biochar for the removal of VOCs from asphalt. Studies have shown that biochar can reduce VOC emissions by approximately 50%, with its adsorption efficacy closely related to the type of biochar used [93,94]. For instance, biochar derived from straw or wood primarily interacts with VOCs through chemical adsorption, whereas biochar derived from pig manure relies more on physical adsorption [95]. By increasing the specific surface area, pore volume, and number of surface chemical functional groups of biochar while simultaneously reducing pore size, the adsorption capacity of biochar in asphalt can be significantly enhanced [96]. Despite the promising potential of biochar in VOC removal, research on the synergistic effects between biochar’s efficiency in VOC elimination and the enhancement of asphalt performance remains relatively scarce. Furthermore, the annual production of 373 million tons of biochar from agricultural waste has the potential to sequester approximately 500 million tons of carbon dioxide each year, equivalent to 1.5% of the global annual CO2 emissions [97,98]. These findings suggest that biochar, as an alternative material, can provide effective solutions for the sustainable development of the pavement industry while simultaneously achieving the dual benefits of environmental and economic improvements.

7.2. Clean Energy

In the production of asphalt mixture equipment, heavy oil is typically used as the primary source of heating energy. However, through technological advancements, cleaner energy sources can be identified and implemented as substitutes for heavy oil. By finding a fuel that is equally effective in heating the aggregate but with lower pollution and emissions, we can take a significant step toward the development of a cleaner society. This approach aligns with the direction of environmental protection and sustainable development. Peng et al. [42] compared the energy emission reduction effects of using coal and natural gas for heating asphalt during the processes of aggregate and asphalt heating. The results indicated that natural gas significantly reduced carbon emissions by 40.92% compared to coal. Moreover, natural gas was also effective in reducing carbon emissions by 27.68% during the aggregate heating process. These findings demonstrate the potential of using natural gas as a cleaner alternative to coal in these high-carbon emission processes. As illustrated in Figure 8, Almeida et al. [99] conducted a comparative study on the CO2 emissions of high-modulus asphalt concrete and crude oil asphalt concrete. They found that converting fossil fuels to natural gas can significantly reduce energy consumption while simultaneously decreasing CO2 emissions and lowering the release of other harmful gases and particulates. Notably, the fuel-related portion constituted only 36% of the total emissions. Paranhos et al. [100] employed a regression model to identify the optimal mixing conditions for reducing energy consumption and emissions from hot mix asphalt (HMA). Their findings revealed that CO2 emissions from natural gas plants were only half of those from fuel oil plants, while nitrogen oxide emissions were reduced by a factor of nine, and CO2 emissions were diminished by a factor of eighteen. Furthermore, small plants were found to have an advantage over large plants in terms of NOx and CO2 emissions. Therefore, changing fuel types clearly helps to reduce carbon emissions and improve energy efficiency in asphalt production processes. Abdalla et al. [101] demonstrated that there are significant environmental advantages to be gained from switching from asphalt-mixed BTS fuel to natural gas in place of heavy fuel oil. The impact on the different environmental impacts of operating an asphalt mixing plant with natural gas compared to the baseline scenario with HFO is shown in Figure 9. Using natural gas instead of HFO is associated with a sustained reduction in environmental impact, as shown by negative relative values indicating a lower risk of environmental impact from AS1 compared to baseline. The most significant relative reductions were observed for acidification, ozone depletion and effects on the respiratory tract in the LC80-A and the LC100-A. Switching the fuel type to natural gas, recognized as the most environmentally friendly fuel, not only significantly reduces carbon emissions but also enhances the energy efficiency of asphalt production. This underscores the importance of transitioning to cleaner energy sources to mitigate the environmental impacts associated with asphalt pavements.

8. Conclusions

This paper examined the use of asphalt pavement for construction purposes, focusing on its impact on energy consumption and carbon dioxide emissions. Over recent decades, there has been a considerable increase in the demand for road infrastructure, accompanied by growing concerns about its detrimental effects on the environment. Consequently, efforts are being made to mitigate the adverse effects of road construction. Based on a review of the relevant literature, the following conclusions can be drawn:
Energy consumption in asphalt mixtures predominantly occurs during three distinct production stages: the heating of aggregates, the heating of asphalt, and the mixing of the asphalt mixtures. The combustion of fuel in asphalt production is the primary source of greenhouse gas emissions. Indeed, aggregate heating accounts for 97% of the energy consumed during this process. Therefore, it is crucial to consider the role of moisture content in the aggregates used. The temperature at which the asphalt mixture is produced directly impacts both manufacturing costs and energy consumption, subsequently affecting greenhouse gas emissions. The use of low-temperature asphalt pavement, compared to hot mix asphalt, results in significant reductions in both energy consumption and greenhouse gas emissions. This, in turn, leads to improved working conditions for plant operators and workers, representing a new and sustainable technology with a positive environmental impact.
The consumption of asphalt during the transportation of materials, the operation of the plant, the transport of mixtures to the construction site, and the placement of these mixtures on the road surface result in considerable environmental impacts, including the production of greenhouse gases such as CO2, CH4, and NO2. The adverse effects of asphalt plant emissions on the ecological environment can be effectively reduced by modifying raw materials, improving heating technology, utilizing alternative heating energy sources, and implementing green emission reduction measures. The use of recycled waste significantly reduces gas emissions, conserves energy, and facilitates material recycling. Additionally, using natural gas instead of fuel oil provides a comparable heating effect for aggregates while significantly reducing carbon emissions. This represents a fundamental transition toward cleaner energy sources that will lead to a sustainable society. The construction of green roads is not only a goal for future infrastructure but also an essential requirement for safeguarding our living environment.
Future research directions should emphasize the application of artificial intelligence (AI) technologies to enhance carbon dioxide emission assessment. By leveraging AI for the modeling and optimization of sustainable low-carbon technologies, significant improvements can be made in evaluating emissions and energy demands associated with various strategies. This approach not only facilitates independent analyses but also strengthens the integration of multiple assessment methods, ultimately leading to more robust and standardized evaluation protocols that adequately account for inherent uncertainties.
Additionally, in the study of sustainable asphalt pavements, analyzing the energy consumption and toxic substance emissions associated with recycled materials is crucial. A thorough exploration of the life cycle impacts of recycled asphalt pavements (RAPs), bioasphalts, and waste tire materials is essential for understanding their environmental implications. The production of these materials often entails significant energy consumption and harmful emissions, making it necessary to assess their environmental impact throughout their entire life cycle. Notably, hazardous substances such as sulfur and zinc present in waste rubber may leach into soil and water, threatening the sustainability of ecological resources. Therefore, prioritizing research on material recovery and ecological protection strategies is essential to mitigate these potential risks.

Author Contributions

Resources and data curation, Y.L.; writing—original draft preparation and writing—review and editing, Z.L.; visualization, Y.Z.; supervision and project administration, H.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

Authors Yancheng Liu and Zhu Youwei were employed by the company Longjian Road & Bridge Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Gkyrtis, K.; Pomoni, M. An Overview of the Recyclability of Alternative Materials for Building Surface Courses at Pavement Structures. Buildings 2024, 14, 1571. [Google Scholar] [CrossRef]
  2. Aryan, Y.; Dikshit, A.K.; Shinde, A.M. A critical review of the life cycle assessment studies on road pavements and road infrastructures. J. Environ. Manag. 2023, 336, 117697. [Google Scholar] [CrossRef]
  3. Jiang, W.; Huang, Y.; Sha, A. A review of eco-friendly functional road materials. Constr. Build. Mater. 2018, 191, 1082–1092. [Google Scholar] [CrossRef]
  4. Rosli, M.H.M.; Chew, J.-W.; Jamshidi, A.; Yang, X.; Hamzah, M.O. Review of sustainability, pretreatment, and engineering considerations of asphalt modifiers from the industrial solid wastes. J. Traffic Transp. Eng. (Engl. Ed.) 2019, 6, 209–244. [Google Scholar]
  5. Sivilevičius, H.; Skrickij, V.; Skačkauskas, P. The Correlation between the Number of Asphalt Mixing Plants and the Production of Asphalt Mixtures in European Countries and the Baltic States. Appl. Sci. 2021, 11, 9375. [Google Scholar] [CrossRef]
  6. Androjic, I.; Kaluder, G.; Androjic, J. Influence of the sun exposure surface area of the solar aggregate stockpiles on the accumulated heat of the stored mineral mixture. Energy 2017, 135, 75–82. [Google Scholar] [CrossRef]
  7. Almeida, A.; Picado-Santos, L. Asphalt Road Pavements to Address Climate Change Challenges-An Overview. Appl. Sci. 2022, 12, 12515. [Google Scholar] [CrossRef]
  8. Azadgoleh, M.A.; Mohammadi, M.M.; Ghodrati, A.; Sharifi, S.S.; Palizban, S.M.M.; Ahmadi, A.; Vahidi, E.; Ayar, P. Characterization of contaminant leaching from asphalt pavements: A critical review of measurement methods, reclaimed asphalt pavement, porous asphalt, and waste-modified asphalt mixtures. Water Res. 2022, 219, 118584. [Google Scholar] [CrossRef]
  9. Yu, X.; Zhang, Z.; Luo, R.; Huang, T.; Xiao, M. Asphalt content prediction model of asphalt mixtures based on dielectric properties. Mater. Struct. 2023, 56, 10. [Google Scholar] [CrossRef]
  10. Zhao, Y.; Hu, Y.; Wu, F.; Zhou, J.; Leng, H. Experimental Study on the Effect of Bottom Ash Powder on the Performance of Porous Asphalt Mixture. J. Chongqing Jiaotong Univ. Nat. Sci. 2022, 41, 93–99. [Google Scholar]
  11. Lehmusto, J.; Tesfaye, F.; Karlstro, O.; Hupa, L. Ashes from challenging fuels in the circular economy. Waste Manag. 2024, 177, 211–231. [Google Scholar] [CrossRef]
  12. Xiao, X.; Liu, T.; Zhao, P.; Luo, G.Z.; Deng, Y. Effect of odour-less additive on asphalt flue gas emission and performance of asphalt and asphalt mixture. Case Stud. Constr. Mater. 2024, 20, e03006. [Google Scholar] [CrossRef]
  13. Li, X.Q.; Wu, S.P.; Wang, F.S.; You, L.Y.; Yang, C.; Cui, P.D.; Zhang, X.M. Quantitative assessments of GHG and VOCs emissions of asphalt pavement contained steel slag. Constr. Build. Mater. 2023, 369, 130606. [Google Scholar] [CrossRef]
  14. Ma, F.; Sha, A.M.; Lin, R.Y.; Huang, Y.; Wang, C. Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China. Int. J. Environ. Res. Public Health 2016, 13, 351. [Google Scholar] [CrossRef] [PubMed]
  15. Liu, Q.; Yi, X.Y.; Falchetto, A.C.; Wang, D.; Yu, B.; Qin, S.Y. Carbon emissions quantification and different models comparison throughout the life cycle of asphalt pavements. Constr. Build. Mater. 2024, 411, 134323. [Google Scholar] [CrossRef]
  16. Azarijafari, H.; Yahia, A.; Ben Amor, M. Life cycle assessment of pavements: Reviewing research challenges and opportunities. J. Clean. Prod. 2015, 112, 2187–2197. [Google Scholar] [CrossRef]
  17. Xiang, Q.; Xiao, F.P. Applications of epoxy materials in pavement engineering. Constr. Build. Mater. 2020, 235, 117529. [Google Scholar] [CrossRef]
  18. Vaitkus, A.; Grazulyte, J.; Sernas, O.; Karbocius, M.; Mickevic, R. Concrete Modular Pavement Structures with Optimized Thickness Based on Characteristics of High Performance Concrete Mixtures with Fibers and Silica Fume. Materials 2021, 14, 3423. [Google Scholar] [CrossRef]
  19. Yuan, Y.; Chen, J.; Lang, H.; Lu, J. Exploring the Efficacy of Sparse Feature in Pavement Distress Image Classification: A Focus on Pavement-Specific Knowledge. Appl. Sci. 2023, 13, 9996. [Google Scholar] [CrossRef]
  20. Yao, K.; Yan, S.Y.; Li, F.J.; Wei, Y.Y.; Tran, C.C. Exploring the effects of road type on drivers’ eye behavior and workload. Int. J. Occup. Saf. Ergon. 2023, 29, 31–35. [Google Scholar] [CrossRef]
  21. Paplauskas, P.; Vaitkus, A. Dependency of Pavement Roughness Level on The Type of Road Works. Balt. J. Road Bridge Eng. 2022, 17, 74–97. [Google Scholar] [CrossRef]
  22. Khan, M.; Rehman, A.; Ali, M. Efficiency of silica-fume content in plain and natural fiber reinforced concrete for concrete road. Constr. Build. Mater. 2020, 244, 118382. [Google Scholar] [CrossRef]
  23. Jiang, B.; Xu, L.; Cao, Z.; Yang, Y.; Sun, Z.; Xiao, F. Interlayer distress characteristics and evaluations of semi-rigid base asphalt pavements: A review. Constr. Build. Mater. 2024, 431, 136441. [Google Scholar] [CrossRef]
  24. Zhao, M.; Xu, X.; Liu, Y.; Wu, C.; Sun, Q.; Pei, Y. Microcracking treatment mechanism of semi-rigid base asphalt pavement with discrete-continuous coupling simulation. Case Stud. Constr. Mater. 2024, 20, e02850. [Google Scholar] [CrossRef]
  25. Zhihao, Y.; Linbing, W.; Dongwei, C.; Yinghao, M.; Hailu, Y. Structural optimization design of semi-rigid base asphalt pavement using modulus matching criterion and multi-indicator range analysis. J. Traffic Transp. Eng. (Engl. Ed.) 2024, 11, 131–159. [Google Scholar]
  26. Vaitkus, A.; Grazulyte, J.; Kleiziene, R.; Vorobjovas, V.; Sernas, O. Concrete Modular Pavements—Types, Issues And Challenges. Balt. J. Road Bridge Eng. 2019, 14, 80–103. [Google Scholar] [CrossRef]
  27. Sahis, M.K.; Biswas, P.P.; Sadhukhan, S.; Saha, G. Mechanistic-empirical Design of Perpetual Road Pavement Using Strain-based Design Approach. Period. Polytech.-Civ. Eng. 2023, 67, 1105–1114. [Google Scholar] [CrossRef]
  28. Kedar, H.N.; Patel, S. Effect of hydraulic binders on engineering properties of coal ash for utilization in pavement layers. Clean Technol. Environ. Policy 2024, 26, 3313–3331. [Google Scholar] [CrossRef]
  29. Pan, Q.X.; Hu, J.; Zheng, J.L.; Lv, S.T.; Zhang, J.H.; Wen, P.H.; Song, X.J. Poisson’s ratio testing method and multi-factor influence quantification model of asphalt pavement materials. Constr. Build. Mater. 2024, 425, 136025. [Google Scholar] [CrossRef]
  30. Xiao, F.P.; Xu, L.; Zhao, Z.F.; Hou, X.D. Recent applications and developments of reclaimed asphalt pavement in China, 2010-2021. Sustain. Mater. Technol. 2023, 37, e00697. [Google Scholar] [CrossRef]
  31. Araneda, M.E.; Pradena, M.; Silva, R.; Pardo, M. Sustainable paving alternative for low-volume roads using cold recycled asphalt. Proc. Inst. Civ. Eng.-Eng. Sustain. 2022, 175, 293–301. [Google Scholar] [CrossRef]
  32. Al-Atroush, M.E. Structural behavior of the geothermo-electrical asphalt pavement: A critical review concerning climate change. Heliyon 2022, 8, e12107. [Google Scholar] [CrossRef] [PubMed]
  33. Androjic, I.; Alduk, Z.D.; Dimter, S.; Rukavina, T. Analysis of impact of aggregate moisture content on energy demand during the production of hot mix asphalt (HMA). J. Clean. Prod. 2020, 244, 118868. [Google Scholar] [CrossRef]
  34. Antunes, V.; Freire, A.C.; Neves, J. Investigating aged binder mobilization and performance of RAP mixtures for surface courses. Constr. Build. Mater. 2021, 271, 121511. [Google Scholar] [CrossRef]
  35. Liu, J.N.; Wang, Z.J.; Jing, H.S.; Jia, H.Y.; Zhou, L.; Chen, H.; Zhang, L. Microwave self-healing characteristics of bituminous mixtures with different steel slag aggregate and waste ferrite filler. Constr. Build. Mater. 2023, 407, 133304. [Google Scholar] [CrossRef]
  36. Hong, Z.; Yan, K.Z.; Wang, M.; Zhang, X.Y. Performance investigation of phenol-formaldehyde resin (PF) and organic montmorillonite (OMMT) compound-modified bituminous mixture. Int. J. Pavement Eng. 2024, 25, 2301451. [Google Scholar] [CrossRef]
  37. Khater, A.; Luo, D.; Abdelsalam, M.; Yue, Y.C.; Hou, Y.Q.; Ghazy, M. Laboratory Evaluation of Asphalt Mixture Performance Using Composite Admixtures of Lignin and Glass Fibers. Appl. Sci. 2021, 11, 364. [Google Scholar] [CrossRef]
  38. Enieb, M.; Diab, A.; Yang, X. Short- and long-term properties of glass fiber reinforced asphalt mixtures. Int. J. Pavement Eng. 2021, 22, 64–76. [Google Scholar] [CrossRef]
  39. Androjic, I.; Marovic, I.; Kaluder, J.; Kaluder, G. Achieving sustainability through the temperature prediction of aggregate stockpiles. J. Clean. Prod. 2019, 219, 451–460. [Google Scholar] [CrossRef]
  40. Rubio, M.D.; Moreno, F.; Martínez-Echevarría, M.J.; Martínez, G.; Vázquez, J.M. Comparative analysis of emissions from the manufacture and use of hot and half-warm mix asphalt. J. Clean. Prod. 2013, 41, 1–6. [Google Scholar] [CrossRef]
  41. Espinoza, J.; Medina, C.; Calabi-Floody, A.; Sanchez-Alonso, E.; Valdes, G.; Quiroz, A. Evaluation of Reductions in Fume Emissions (VOCs and SVOCs) from Warm Mix Asphalt Incorporating Natural Zeolite and Reclaimed Asphalt Pavement for Sustainable Pavements. Sustainability 2020, 12, 9546. [Google Scholar] [CrossRef]
  42. Peng, B.; Tong, X.; Cao, S.; Li, W.; Xu, G. Carbon Emission Calculation Method and Low-Carbon Technology for Use in Expressway Construction. Sustainability 2020, 12, 3219. [Google Scholar] [CrossRef]
  43. Zhang, R.; Tang, N.; Zhu, H.; Xi, Y.; Sheng, W.; Li, Z. Short-term emission behavior and evolution law of organic emissions from asphalt binder materials. Constr. Build. Mater. 2024, 433, 136498. [Google Scholar] [CrossRef]
  44. Martin, H.; Kerstin, Z.; Joachim, M. Reduced emissions of warm mix asphalt during construction. Road Mater. Pavement Des. Int. J. 2019, 20, S568–S577. [Google Scholar] [CrossRef]
  45. Kumar, R.; Saboo, N.; Kumar, P.; Chandra, S. Effect of warm mix additives on creep and recovery response of conventional and polymer modified asphalt binders. Constr. Build. Mater. 2017, 138, 352–362. [Google Scholar] [CrossRef]
  46. Autelitano, F.; Bianchi, F.; Giuliani, F. Airborne emissions of asphalt/wax blends for warm mix asphalt production. J. Clean. Prod. 2017, 164, 749–756. [Google Scholar] [CrossRef]
  47. Jamshidi, A.; Hamzah, M.O.; You, Z. Performance of Warm Mix Asphalt containing Sasobit (R): State-of-the-art. Constr. Build. Mater. 2013, 38, 530–553. [Google Scholar] [CrossRef]
  48. Ranieri, V.; Kowalski, K.J.; Berloco, N.; Colonna, P.; Perrone, P. Influence of wax additives on the properties of porous asphalts. Constr. Build. Mater. 2017, 145, 261–271. [Google Scholar] [CrossRef]
  49. Hasan, M.R.M.; You, Z.; Yang, X. A comprehensive review of theory, development, and implementation of warm mix asphalt using foaming techniques. Constr. Build. Mater. 2017, 152, 115–133. [Google Scholar] [CrossRef]
  50. Zaumanis, M.; Mallick, R.B.; Frank, R. 100% recycled hot mix asphalt: A review and analysis. Resour. Conserv. Recycl. 2014, 92, 230–245. [Google Scholar] [CrossRef]
  51. Huynh, A.T.; Magee, B.; Woodward, D. A Preliminary Characterisation of Innovative Semi-Flexible Composite Pavement Comprising Geopolymer Grout and Reclaimed Asphalt Planings. Materials 2020, 13, 3644. [Google Scholar] [CrossRef] [PubMed]
  52. He, J.X.; Ma, Y.T.; Zheng, K.P.; Cheng, Z.Q.; Xie, S.J.; Xiao, R.; Huang, B.S. Quantifying the agglomeration effect of reclaimed asphalt pavement on performance of recycled hot mix asphalt. J. Clean. Prod. 2024, 442, 141044. [Google Scholar] [CrossRef]
  53. Nanda, H.; Siddagangaiah, A.K. Effect of RAP fractionation and dosage on design and mechanical behaviour of cold asphalt mixes. Constr. Build. Mater. 2024, 422, 135773. [Google Scholar] [CrossRef]
  54. Franzitta, V.; Longo, S.; Sollazzo, G.; Cellura, M.; Celauro, C. Primary Data Collection and Environmental/Energy Audit of Hot Mix Asphalt Production. Energies 2020, 13, 2045. [Google Scholar] [CrossRef]
  55. Kharat, D. Emissions from Hot Mix Asphalt Plants and their Impact on Ambient Air Quality. Water Air Soil Pollut. 2022, 233, 464. [Google Scholar] [CrossRef]
  56. Peinado, D.; Vega, M.D.; García-Hernando, N.; Marugán-Cruz, C. Energy and exergy analysis in an asphalt plant’s rotary dryer. Appl. Therm. Eng. 2011, 31, 1039–1049. [Google Scholar] [CrossRef]
  57. Androjic, I.; Kaluder, G. Usage of solar aggregate stockpiles in the production of hot mix asphalt. Appl. Therm. Eng. 2016, 108, 131–139. [Google Scholar] [CrossRef]
  58. Androjic, I.; Marovic, I.; Kaluder, G.; Androjic, J. Application of solar aggregate stockpiles in the process of storing recycled materials. Int. J. Energy Res. 2019, 43, 6269–6282. [Google Scholar] [CrossRef]
  59. Gruber, M.R.; Hofko, B. Life Cycle Assessment of Greenhouse Gas Emissions from Recycled Asphalt Pavement Production. Sustainability 2023, 15, 4629. [Google Scholar] [CrossRef]
  60. Ferrotti, G.; Mancinelli, E.; Passerini, G.; Canestrari, F. Comparison of energy and environmental performance between warm and hot mix asphalt concrete production: A case study. Constr. Build. Mater. 2024, 418, 135453. [Google Scholar] [CrossRef]
  61. Schoenauer, P.; Gruber, M.R.; Hofko, B. Case study of a batch asphalt mix plant: Energy consumption and emission allocation based on primary data. Case Stud. Constr. Mater. 2024, 21, e03669. [Google Scholar] [CrossRef]
  62. Martisius, M.; Sivilevicius, H. The Modelling of Emissions Evaluation at Asphalt Mixing Plant in Hot Recycling. Transport 2022, 37, 137–144. [Google Scholar] [CrossRef]
  63. Khare, P.; Machesky, J.; Soto, R.; He, M.G.; Presto, A.A.; Gentner, D.R. Asphalt-related emissions are a major missing nontraditional source of secondary organic aerosol precursors. Sci. Adv. 2020, 6, eabb9785. [Google Scholar] [CrossRef] [PubMed]
  64. Cao, S.; Peng, B.; Zhang, B.; Long, K.; Cheng, Z.; Qi, Y. Study of quantitative methods for emission of greenhouse gases during construction period of asphalt pavement and emission reduction countermeasures. J. Dalian Univ. Technol. 2019, 59, 385–392. [Google Scholar]
  65. Yingli, H.; Zhenhua, Q.; Ying, Z.; Haitao, Z. Life-cycle assessment of carbon dioxide emissions of asphalt pavements in China. Proc. Inst. Civ. Eng.—Eng. Sustain. 2020, 173, 228–240. [Google Scholar] [CrossRef]
  66. Yaro, N.S.A.; Sutanto, M.H.; Baloo, L.; Habib, N.Z.; Usman, A.; Yousafzai, A.K.; Ahmad, A.; Birniwa, A.H.; Jagaba, A.H.; Noor, A. A Comprehensive Overview of the Utilization of Recycled Waste Materials and Technologies in Asphalt Pavements: Towards Environmental and Sustainable Low-Carbon Roads. Processes 2023, 11, 2095. [Google Scholar] [CrossRef]
  67. Liu, Y.; Li, H.; Wang, H.; Wang, Y.; Han, S. Integrated Life Cycle Analysis of Cost and CO2 Emissions from Vehicles and Construction Work Activities in Highway Pavement Service Life. Atmosphere 2023, 14, 194. [Google Scholar] [CrossRef]
  68. Yaro, N.S.A.; Sutanto, M.H.; Habib, N.Z.; Usman, A.; Kaura, J.M.; Murana, A.A.; Birniwa, A.H.; Jagaba, A.H. A Comprehensive Review of Biochar Utilization for Low-Carbon Flexible Asphalt Pavements. Sustainability 2023, 15, 6729. [Google Scholar] [CrossRef]
  69. Medina, T.; Calmon, J.L.; Vieira, D.; Bravo, A.; Vieira, T. Life Cycle Assessment of Road Pavements That Incorporate Waste Reuse: A Systematic Review and Guidelines Proposal. Sustainability 2023, 15, 14892. [Google Scholar] [CrossRef]
  70. Ruiz, A.; Guevara, J. Sustainable Decision-Making in Road Development: Analysis of Road Preservation Policies. Sustainability 2020, 12, 872. [Google Scholar] [CrossRef]
  71. Giani, M.I.; Dotelli, G.; Brandini, N.; Zampori, L. Comparative life cycle assessment of asphalt pavements using reclaimed asphalt, warm mix technology and cold in-place recycling. Resour. Conserv. Recycl. 2015, 104, 224–238. [Google Scholar] [CrossRef]
  72. Gulotta, T.M.; Mistretta, M.; Pratico, F.G. A life cycle scenario analysis of different pavement technologies for urban roads. Sci. Total Environ. 2019, 673, 585–593. [Google Scholar] [CrossRef] [PubMed]
  73. Wang, Q.; Xu, D.; Huang, J.; Wan, J. Energy Saving and Emission Reduction Benefit Evaluation of Cold Recycling Technology with Foam Asphalt. Environ. Eng. 2018, 36, 179–183. [Google Scholar]
  74. Feng, H.; Prozzi, J.A. Evaluation of recycled asphalt pavement using economic, environmental, and energy metrics based on long-term pavement performance sections. Road Mater. Pavement Des. 2018, 19, 1816–1831. [Google Scholar] [CrossRef]
  75. Jahanbakhsh, H.; Karimi, M.M.; Naseri, H.; Moghadas Nejad, F. Sustainable asphalt concrete containing high reclaimed asphalt pavements and recycling agents: Performance assessment, cost analysis, and environmental impact. J. Clean. Prod. 2020, 244, 118837. [Google Scholar] [CrossRef]
  76. Oreto, C.; Veropalumbo, R.; Viscione, N.; Biancardo, S.A.; Russo, F. Investigating the environmental impacts and engineering performance of road asphalt pavement mixtures made up of jet grouting waste and reclaimed asphalt pavement. Environ. Res. 2021, 198, 111277. [Google Scholar] [CrossRef]
  77. Tushar, Q.; Santos, J.; Zhang, G.M.; Bhuiyan, M.A.; Giustozzi, F. Recycling waste vehicle tyres into crumb rubber and the transition to renewable energy sources: A comprehensive life cycle assessment. J. Environ. Manag. 2022, 323, 116289. [Google Scholar] [CrossRef]
  78. Wang, Q.-Z.; Chen, Z.-D.; Lin, K.-P.; Wang, C.-H. Estimation and Analysis of Energy Conservation and Emissions Reduction Effects of Warm-Mix Crumb Rubber-Modified Asphalts during Construction Period. Sustainability 2018, 10, 4521. [Google Scholar] [CrossRef]
  79. Wang, Q.-Z.; Wang, N.-N.; Tseng, M.-L.; Huang, Y.-M.; Li, N.-L. Waste tire recycling assessment: Road application potential and carbon emissions reduction analysis of crumb rubber modified asphalt in China. J. Clean. Prod. 2019, 249, 119411. [Google Scholar] [CrossRef]
  80. Moghimi, S.; Shafabakhsh, G.; Divandari, H. Evaluation of Rutting, Fatigue, and Moisture Resistance of Low-Energy Asphalt Mixtures Modified by Crumb Rubber. Adv. Civ. Eng. 2023, 2023, 1–21. [Google Scholar] [CrossRef]
  81. Shulman, V.L. 1—An introduction to tires and recycling. In Tire Waste and Recycling; Letcher, T.M., Shulman, V.L., Amirkhanian, S., Eds.; Academic Press: Cambridge, MA, USA, 2021; pp. 3–14. [Google Scholar]
  82. Cui, D.; Bi, Z.; Wang, Y.; Gu, Y.; Wang, H.; Gao, X.; Wang, P.; Sun, X.; Chen, W.-Q. Scenario analysis of waste tires from China’s vehicles future. J. Clean. Prod. 2024, 478, 143940. [Google Scholar] [CrossRef]
  83. Chen, B.; Zheng, D.; Xu, R.; Leng, S.; Han, L.; Zhang, Q.; Liu, N.; Dai, C.; Wu, B.; Yu, G.; et al. Disposal methods for used passenger car tires: One of the fastest growing solid wastes in China. Green Energy Environ. 2022, 7, 1298–1309. [Google Scholar] [CrossRef]
  84. Hu, H.; Liu, J.; Zhu, Q.; Chen, Q. An integrated supply chain management system for end-of-life tires in China and its promotion barriers: A stakeholder perspective. Resour. Conserv. Recycl. 2021, 164, 105214. [Google Scholar] [CrossRef]
  85. Wang, L.; Zhu, S.; Evans, S.; Zhang, Z.; Xia, X.; Guo, Y. Automobile recycling for remanufacturing in China: A systematic review on recycling legislations, models and methods. Sustain. Prod. Consum. 2023, 36, 369–385. [Google Scholar] [CrossRef]
  86. Zhao, Q.; Chen, M. A comparison of ELV recycling system in China and Japan and China’s strategies. Resour. Conserv. Recycl. 2011, 57, 15–21. [Google Scholar] [CrossRef]
  87. Soo, V.K.; Doolan, M.; Compston, P.; Duflou, J.R.; Peeters, J.; Umeda, Y. The influence of end-of-life regulation on vehicle material circularity: A comparison of Europe, Japan, Australia and the US. Resour. Conserv. Recycl. 2021, 168, 105294. [Google Scholar] [CrossRef]
  88. Lu, Y.; Hussein, A.; Lauzon-Gauthier, J.; Ollevier, T.; Alamdari, H. Biochar as an Additive to Modify Biopitch Binder for Carbon Anodes. Acs Sustain. Chem. Eng. 2021, 9, 12406–12414. [Google Scholar] [CrossRef]
  89. Saadeh, S.; Al-Zubi, Y.; Katawal, P.; Zaatarah, B.; Fini, E. Biochar effects on the performance of conventional and rubberized HMA. Road Mater. Pavement Des. 2023, 24, 156–172. [Google Scholar] [CrossRef]
  90. Tripathi, N.; Hills, C.D.; Singh, R.S.; Atkinson, C.J. Biomass waste utilisation in low-carbon products: Harnessing a major potential resource. npj Clim. Atmos. Sci. 2019, 2, 35. [Google Scholar] [CrossRef]
  91. Zhou, X.; Moghaddam, T.B.; Chen, M.; Wu, S.; Adhikari, S.; Xu, S.; Yang, C. Life Cycle Assessment of Biochar Modified Bioasphalt Derived from Biomass. Acs Sustain. Chem. Eng. 2020, 8, 14568–14575. [Google Scholar] [CrossRef]
  92. Cui, P.; Schito, G.; Cui, Q. VOC emissions from asphalt pavement and health risks to construction workers. J. Clean. Prod. 2020, 244, 118757. [Google Scholar] [CrossRef]
  93. Zhou, A.; Tam, L.-h.; Yu, Z.; Lau, D. Effect of moisture on the mechanical properties of CFRP–wood composite: An experimental and atomistic investigation. Compos. Part B Eng. 2015, 71, 63–73. [Google Scholar] [CrossRef]
  94. Osman, A.I.; Fawzy, S.; Farghali, M.; El-Azazy, M.; Elgarahy, A.M.; Fahim, R.A.; Maksoud, M.I.A.A.; Ajlan, A.A.; Yousry, M.; Saleem, Y.; et al. Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: A review. Environ. Chem. Lett. 2022, 20, 2385–2485. [Google Scholar] [CrossRef] [PubMed]
  95. Zhang, X.; Xiang, W.; Wang, B.; Fang, J.; Zou, W.; He, F.; Li, Y.; Tsang, D.C.W.; Ok, Y.S.; Gao, B. Adsorption of acetone and cyclohexane onto CO2 activated hydrochars. Chemosphere 2020, 245, 125664. [Google Scholar] [CrossRef] [PubMed]
  96. Li, X.; Zhang, L.; Yang, Z.; Wang, P.; Yan, Y.; Ran, J. Adsorption materials for volatile organic compounds (VOCs) and the key factors for VOCs adsorption process: A review. Sep. Purif. Technol. 2020, 235, 116213. [Google Scholar] [CrossRef]
  97. Yang, J.; Tang, L.-S.; Bai, L.; Bao, R.-Y.; Liu, Z.-Y.; Xie, B.-H.; Yang, M.-B.; Yang, W. High-performance composite phase change materials for energy conversion based on macroscopically three-dimensional structural materials. Mater. Horiz. 2019, 6, 250–273. [Google Scholar] [CrossRef]
  98. Lehmann, J.; Cowie, A.; Masiello, C.A.; Kammann, C.; Woolf, D.; Amonette, J.E.; Cayuela, M.L.; Camps-Arbestain, M.; Whitman, T. Biochar in climate change mitigation. Nat. Geosci. 2021, 14, 883–892. [Google Scholar] [CrossRef]
  99. Almeida-Costa, A.; Benta, A. Economic and environmental impact study of warm mix asphalt compared to hot mix asphalt. J. Clean. Prod. 2016, 112, 2308–2317. [Google Scholar] [CrossRef]
  100. Paranhos, R.S.; Petter, C.O. Multivariate data analysis applied in Hot-Mix asphalt plants. Resour. Conserv. Recycl. 2013, 73, 1–10. [Google Scholar] [CrossRef]
  101. Abdalla, A.; Faheem, A.F.; Walters, E. Life cycle assessment of eco-friendly asphalt pavement involving multi-recycled materials: A comparative study. J. Clean. Prod. 2022, 362, 132471. [Google Scholar] [CrossRef]
Applsci 14 10246 g001
Figure 1. Annual production of asphalt mixtures [5,6].
Figure 1. Annual production of asphalt mixtures [5,6].
Applsci 14 10246 g001
Applsci 14 10246 g002
Figure 2. Research methodology.
Figure 2. Research methodology.
Applsci 14 10246 g002
Applsci 14 10246 g003
Figure 3. The asphalt concrete pavement structure.
Figure 3. The asphalt concrete pavement structure.
Applsci 14 10246 g003
Applsci 14 10246 g004
Figure 4. Classification by temperature range and potential energy savings [39].
Figure 4. Classification by temperature range and potential energy savings [39].
Applsci 14 10246 g004
Applsci 14 10246 g005
Figure 5. Emissions from hot mix asphalt plants and their effect on ambient air quality [55].
Figure 5. Emissions from hot mix asphalt plants and their effect on ambient air quality [55].
Applsci 14 10246 g005
Applsci 14 10246 g006
Figure 6. Relationship between the exposed ceiling surface area and the temperature of the mineral mixture. The ceiling glass window areas are as follows: Model A: 0.36 × 0.36 m; Model B: 0.25 × 0.25 m; Model C: 0.10 × 0.10 m; Model R: 0.6 m in diameter [6].
Figure 6. Relationship between the exposed ceiling surface area and the temperature of the mineral mixture. The ceiling glass window areas are as follows: Model A: 0.36 × 0.36 m; Model B: 0.25 × 0.25 m; Model C: 0.10 × 0.10 m; Model R: 0.6 m in diameter [6].
Applsci 14 10246 g006
Applsci 14 10246 g007
Figure 7. Carbon emissions of 12 expressways [42]: (a) carbon emissions from energy consumption; (b) asphalt mixture carbon emissions. (A: Jingqin Expressway; B: Jishan Expressway; C: Huangyan Expressway; D: Sancha Expressway; E: Xixian Expressway; F: Pengteng Expressway; G: Liaoyu Expressway; H: G3014; I: G310; J: Yanyan Expressway; K: West Copper Expressway; and L: Binhai Expressway).
Figure 7. Carbon emissions of 12 expressways [42]: (a) carbon emissions from energy consumption; (b) asphalt mixture carbon emissions. (A: Jingqin Expressway; B: Jishan Expressway; C: Huangyan Expressway; D: Sancha Expressway; E: Xixian Expressway; F: Pengteng Expressway; G: Liaoyu Expressway; H: G3014; I: G310; J: Yanyan Expressway; K: West Copper Expressway; and L: Binhai Expressway).
Applsci 14 10246 g007
Applsci 14 10246 g008
Figure 8. CO2 emissions from fuel combustion during synthetic HMAC production [99].
Figure 8. CO2 emissions from fuel combustion during synthetic HMAC production [99].
Applsci 14 10246 g008
Applsci 14 10246 g009
Figure 9. The variation of the LCIA results of utilizing natural gas in the asphalt mixture production as an alternative scenario relative to the baseline scenario [101].
Figure 9. The variation of the LCIA results of utilizing natural gas in the asphalt mixture production as an alternative scenario relative to the baseline scenario [101].
Applsci 14 10246 g009
Table 1. Heating and drying of materials in the hot mix asphalt production process as studied in previous research.
Table 1. Heating and drying of materials in the hot mix asphalt production process as studied in previous research.
ReferenceYear and Area of AnalysisResult
Androjić and KaluCer [57]2016 Effect of variable insulation thickness on the use of solar panels.Solar aggregate piles preheat the mineral mix and reduce moisture content, reducing the energy required to produce warm mix asphalt.
Androjić et al. [6]2017 Use of the stockpiles of solar aggregates—influence of the variable surface area of the stockpiles of solar aggregates exposed to the sun.Influence of the variable solar surface area of a solar pile on the heat accumulation results of mineral mixtures in different seasons (summer–autumn). For every 10 °C increase in temperature, a potential energy saving of 3.7 kWh can be calculated.
Androjić et al. [58]2019 Utilization of solar aggregate stockpiles—storage of recycled materials.Influence of time spent in sunlight, type of material stored, method of storage, and time stored.
Androjić et al. [39]2019 Predicting the temperature of stored materials—using solar thermal storage.Temperature prediction of stored materials using solar aggregate reserve storage. Lower temperatures were predicted for mixtures stored at 0 °C air temperature and higher values at 30 °C air temperature.
Androjić et al. [33]2019 The energy consumption of asphalt mixes is significantly influenced by the moisture content of the aggregates.Removing 1% water from a mineral mixture requires 7.34 kWh of thermal energy.
Gruber and Hofko [59]2023 Effect of aggregate moisture content on greenhouse gas emissions.Total greenhouse gas emissions are 47.1 kg CO2e/t for natural aggregates with a moisture content of 5% (0%: 36.6 kg CO2e/t).
Ferrotti et al. [60]2024 Unit drying/heating reduces fuel oil consumption.Drying/heating units cut PM, Nox, and VOC emissions by around 18 percent, 22 percent, and 35 percent, respectively.
Table 2. Energy and heavy oil consumption of different mix CRMAs [78].
Table 2. Energy and heavy oil consumption of different mix CRMAs [78].
Asphalt MixturesTotal Energy Consumption (MJ)Energy Conserved (%)Heavy Oil Consumption (kg)Heavy Oil Conserved (kg)
Hot mixingCRMA300.89—7.65—
Sa-CRMA238.6220.696.071.58
Warm mixingEv-DAT CRMA192.3336.084.892.67
TOR-CRMA245.8318.306.251.40
Asp-CRMA245.8718.286.251.40
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Liu, Y.; Liu, Z.; Zhu, Y.; Zhang, H. A Review of Sustainability in Hot Asphalt Production: Greenhouse Gas Emissions and Energy Consumption. Appl. Sci. 2024, 14, 10246. https://doi.org/10.3390/app142210246

AMA Style

Liu Y, Liu Z, Zhu Y, Zhang H. A Review of Sustainability in Hot Asphalt Production: Greenhouse Gas Emissions and Energy Consumption. Applied Sciences. 2024; 14(22):10246. https://doi.org/10.3390/app142210246

Chicago/Turabian Style

Liu, Yancheng, Zhengyi Liu, Youwei Zhu, and Haitao Zhang. 2024. "A Review of Sustainability in Hot Asphalt Production: Greenhouse Gas Emissions and Energy Consumption" Applied Sciences 14, no. 22: 10246. https://doi.org/10.3390/app142210246

APA Style

Liu, Y., Liu, Z., Zhu, Y., & Zhang, H. (2024). A Review of Sustainability in Hot Asphalt Production: Greenhouse Gas Emissions and Energy Consumption. Applied Sciences, 14(22), 10246. https://doi.org/10.3390/app142210246

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop