Advancements and Challenges in the Use of Cold Mix Asphalt for Sustainable and Cost-Effective Pavement Solutions

Abstract

Even with the high advancement of the pavement industry, the use of traditional hot mix asphalt (HMA) for pavement construction and maintenance is associated with high energy consumption, greenhouse gas emissions, and production costs. As a result, researchers and industrial practitioners aspire to use cold mix asphalt (CMA) as an alternative that offers environmental and economic benefits. This paper provides an overview of the advancements and challenges in using CMA for sustainable and cost-effective pavement solutions. The paper reviews portrays, and discloses CMA’s recent benefits, such as reduced energy consumption, lower emissions, and enhanced durability. Additionally, the paper addresses the challenges associated with using CMA, including its limited application areas and potential performance issues. It discusses the strategies being developed to overcome these challenges. Furthermore, the paper concludes with recommendations for the future of research and industry development of CMA to further promotion. Meanwhile, it is finalizing the current sight for using CMA as a sustainable, cost-effective pavement solution.

Full text

Advancements and Challenges in the Use of Cold Mix Asphalt for
Sustainable and Cost-Effective Pavement Solutions
Zahraa Al-Hashimi1, a*, Shakir Al-Busaltan 1, b and Bahaa Al-Abbas1, c
1 Department of Civil Engineering, College of Engineering, University of Karbala, Karbala, Iraq
aZahraa.hashim@uokerbala.edu.iq , bs.f.al-busultan@uokerbala.edu.iq and
cbahaa.hussain@uokerbala.edu.iq
*Corresponding author
Abstract. Even with the high advancement of the pavement industry, the use of traditional hot mix asphalt
(HMA) for pavement construction and maintenance is associated with high energy consumption,
greenhouse gas emissions, and production costs. As a result, researchers and industrial practitioners
aspire to use cold mix asphalt (CMA) as an alternative that offers environmental and economic benefits.
This paper provides an overview of the advancements and challenges in using CMA for sustainable and
cost-effective pavement solutions. The paper reviews portrays, and discloses CMA's recent benefits, such
as reduced energy consumption, lower emissions, and enhanced durability. Additionally, the paper
addresses the challenges associated with using CMA, including its limited application areas and potential
performance issues. It discusses the strategies being developed to overcome these challenges.
Furthermore, the paper concludes with recommendations for the future of research and industry
development of CMA to further promotion. Meanwhile, it is finalizing the current sight for using CMA as a
sustainable, cost-effective pavement solution.
Keywords: Asphalt; Bitumen material; Challenges and Economic benefits; Cold mix asphalt; Cost-
effective pavement solutions; Sustainable pavement solutions.
1. INTRODUCTION
No doubt, pavement construction, and maintenance are significant contributors to greenhouse gas
emissions and climate change, with traditional hot mix asphalt (HMA) production and transportation being
major sources of energy consumption and carbon emissions. According to the U.S. Environmental
Protection Agency, the transportation sector is responsible for nearly 27% of the total U.S. greenhouse
gas emissions, with road transportation being the largest contributor[1]. Cold mix asphalt (CMA) has
emerged as a promising alternative to HMA for sustainable and cost-effective pavement solutions,
potentially reducing energy consumption and greenhouse gas emissions while improving pavement
performance and durability. Where CMA is produced and applied at ambient temperatures, eliminating the
need for high-temperature production and reducing energy consumption and greenhouse gas
emissions[2, 3]. In addition, CMA can be produced using a variety of materials, including recycled asphalt
pavement, which further reduces environmental impact and project costs[4-6]. Recent research has
demonstrated CMA's environmental and economic benefits, including reduced carbon footprint, lower
construction and maintenance costs, and improved sustainability [7-9].
Nevertheless, challenges remain significant in implementing CMA, including performance issues such
as rutting, cracking, and stripping, as well as quality control and testing issues, such as lack of
standardization and limited testing protocols[10]. Technological barriers, such as limited availability of
equipment and materials, limited expertise and training, and limited research and development, also pose
challenges to wider adoption and acceptance of CMA technology. This paper aims to review and analyze
the recent advancements and challenges in using CMA for sustainable and cost-effective pavement
solutions. The paper discusses the properties and benefits of CMA, such as its ability to be used in cold
weather conditions, reduced energy consumption during production, and its potential for use in low-volume
roads. The authors also examine the challenges associated with using CMA, such as its potential for lower
strength and durability compared to HMA, and the need for improved quality control during production.
Overall, the paper aims to provide insights into the use of CMA as a sustainable and cost-effective
alternative to HMA in pavement construction and to highlight areas where further research and
development are needed to enhance the performance and durability of CMA. Case studies of real-world
projects using cold-mix asphalt as a sustainable and cost-effective pavement solution will also be
presented.
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons
Attribution License 4.0 (https://creativecommons.org/licenses/by/4.0/).
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2. THE GLOBAL ADOPTION OF COLD-MIX ASPHALT
CMA technology has been in use by the pavement industry in multiple countries since the 1960s,
Grave emulsion, a cold reprofiling asphalt, was developed in France in the 1970s; this type of CMA was
standardized by Leech [11]. In France alone in the last decade, for example, annual manufacturing levels
of 1.5 million tons were achieved for these mixtures, which has contributed to the development of a
comprehensive understanding of their performance [12]. The warm and dry climate in France nominated
location facilitates the curing process of the emulsion. As a result, this technology has also gained
recognition in Spain [13], Ireland [14,15], USA [16], and Chania [17].
Interestingly, the favorable climate, in combination with the large distances between hot-mix plants
and job sites, has led to wider adoption of CMA in the USA. During the 1970s, Chevron's research on
stabilized paving mixtures with emulsified bitumen in the USA led to the development of a practical
guideline for producing such mixes [18]. Accordingly, the Asphalt Institute has suggested Hveem and
Marshall design methods for both in-situ and plant mixed materials in his designated publication MS-14
[19] in the 1980’s, while three editions of this design manual have been published.
Despite several efforts, the UK has been slow to adopt CMA on a large scale. The Highway Authorities
and Utilities Committee (HAUC) attempted to encourage the use of storable cold mixes with in-situ
performance equivalent to HMA after installation through the publication of the "New Roads and Street
Works Act" document in 1991, which included an appendix A10 specifying the requirements for
reinstatement of openings in highways[20].In addition, CMA has gained interest in several other countries,
including various European nations, South Africa, Australia, and New Zealand [21]. In Sweden, for
example, cold recycled asphalt materials are commonly utilized for flexible pavements due to the large
amount of old pavements that are recycled each year, estimated to be around 1 million tons [22]. Spain,
another example, has been utilizing emulsion mixtures since the late 1950s. As stated by Needham in
1996, these mixtures consist of either gravel or open-graded materials [7]. High viscosity, medium setting,
cationic, or anionic emulsions were used in open-graded mixtures to ensure a thick bitumen coating on
the aggregate. In South Africa, the implementation of bitumen emulsion for base construction is
spearheaded by the South African Bitumen Association (SABITA). Recognizing the advantages of this
method, SABITA released various design guidelines and standards in 1993 and 1999[7]. In China, cold
patch asphalt plays an important role in maintaining China's vast network of roads and highways[17].
In the past few years, there has been a rise in the number of research studies dedicated to exploring
(CMA) as a viable pavement solution. Several countries and regions have acknowledged the potential
advantages of employing CMA. According to Scopus, a widely recognized database [23, 24, 25], to date,
approximately 980 documents were published on CMA between 1970 and 2023. Figure 1 illustrates the
trend in the number of publications and documents per year (from 2000 to 2020) and the number of
documents by country related to CMA, as shown in Figure 2. Many conclusions can be disclosed from
these figures, mainly the steady increment in the number of research continually. Also, as expected, there
is a variety of interest in both developed and developing countries, where the developed countries are
predominated this research sector. The last is a vital indicator of the significance of this branch of
knowledge.
Figure 1: Number of research documents on cold mix asphalt by year (graph sourced from Scopus)[26].
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Figure 2: Number of research documents on cold mix asphalt by country (graph sourced from Scopus)
[26].
3. SUSTAINABILITY BENEFITS OF COLD MIX ASPHALT
CMA offers a range of sustainability benefits, making it an attractive pavement solution for
environmentally conscious projects. The use of cold-mixed asphalt reduces the amount of energy needed
during production and placement compared to HMA, as it does not require heating. When considering
energy consumption per ton of laid material, both CMA and cold in-situ recycling methods utilize less
energy compared to HMA and hot in-situ recycling methods. Specifically, the cold in-situ recycling method
has the lowest energy consumption due to its lower requirement for binder and the fact that reclaimed
aggregates are used. To manufacture one ton of laid material, HMA consumes 680 MJ of energy, while
CMA and cold in-situ recycling consume 2/3 and 1/5 of this amount, respectively. Therefore, it can be
concluded that CMA is more energy-efficient than HMA[27]. Figure 3 presents information on the total
energy utilized in constructing various asphalt mixes, including the energy consumption associated with
each component. This data is based on a study conducted by Chappat and Bilaj [28]. Since CMA is
produced at ambient temperature, using a hydraulic mixture for concrete mix or manual mixing is
preferable. Using a cold recycled mix can reduce 52% of Greenhouse Gas (GHG) emissions and 54% of
nitrogen oxide emissions. Furthermore, aggregate consumption can be reduced by up to 62%.[28]. Figure
4 displays the data on the total gas emissions produced during the construction of various asphalt mixes
and the gas emissions associated with individual components[28].
On the other side, CMA is often produced using recycled materials, such as reclaimed asphalt
pavement (RAP) and recycled asphalt shingles (RAS), which reduce waste and conserve natural
resources[6]. Using recycled materials in the cold mix as CMA asphalt production can also reduce the
need for virgin aggregates and asphalt binders, reducing environmental impact[29]. Overall, the
sustainability benefits of CMA make it a promising pavement solution for sustainable infrastructure
development.
Several recent studies have demonstrated the sustainability benefits of cold-mixed asphalt. The
National Cooperative Highway Research Program (NCHRP) published a synthesis in 2018 highlighting
the reduced environmental impact of CMA through recycled materials[30]. According to Lu et al. in 2013,
CMA is significantly superior to HMA and WMA. It is now widely used to minimize potholes, eliminating
the need for an aggregate dryer and heating mix or aggregates, resulting in considerable energy
savings[31]. Table 1, summarizing these recent studies, shows that using CMA can offer several
sustainability benefits, making it an attractive pavement solution for environmentally conscious projects.
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Figure 3: The energy required for producing various asphalt mixes type [28].
Figure 4: The GHG emission required for producing various asphalt mixes type [28].
Table 1: Recent studies on sustainability benefits of cold mix asphalt.
Author(s)
Date
Materials
Benefits
Kari [32] 1973
Use of emulsified asphalt
instead of cutback asphalt
Reduced energy consumption
Jenkins [33] 2000
Use of emulsified asphalt and
foamed bitumen
Cost savings and Reduced energy consumption
Chehovits and
Galehouse [34]
2010
Use CMA construction
technologies
Construction of CMA is 95% less energy
consumption compared to HMA and WMA
Al-Busaltan et
al. [35]
2012
Use of emulsified asphalt with
cement and fly ash
Cost savings and environmentally friendly
Hussain and
Yanjun [36]
2013
Use of reclaimed asphalt
pavement (RAP)
cost-effective and eco-friendly material.
Dondi et al. [37] 2014 Use of crumb rubber
Cost savings and environmentally friendly for
CMA than HMA
Xiao et al. [38] 2018 use of a cold recycled mix
This technology can decrease GHG, nitrogen
oxide, and sulfur dioxide emissions by 52% and
54%, respectively. Additionally, it can reduce
aggregate consumption by up to 62%.
Pasetto et al.
[39]
2019
Use of recycled asphalt
shingles (RAS)
Reduced energy consumption and carbon
dioxide emissions
Offenbacker et
al. [40]
2021
use of a recycled mix of CMA
or cold in-place recycling
(CIR) technology
Implementing this technology led to a reduction
in energy consumption by 57% to 63%, resulting
in significant cost savings of up to $10,000 to
$12,000.
Singh and Jain
[41]
2022
Use of emulsified asphalt with
cement and hydrated lime
Cost savings
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4. CHALLENGES IN IMPLEMENTING COLD MIX ASPHALT PROJECTS
CMA has several advantages as a pavement solution, but it also presents a range of challenges. The
use of CMA in some countries can pose several administrative, logistical, and technical challenges. Here
are some of these challenges in more detail:
4.1 Administrative and Logistical Challenges
The implementation of novel technologies like CMA pavement could create several administrative and
logistical hurdles for nations, according to findings conducted by authors' survey on local experts’
interviews and global governmental reports and publications. The challenges can be identified as:
1. Lack of awareness: The lack of awareness about the benefits of CMA may make it difficult for some
countries to accept and adopt this new technology.
2. Resistance to change: Normally, highway authorities value their current practice, i.e., some
authorities may resist changing their existing practices and adopting new technologies, especially if
they have invested heavily in traditional pavement construction methods.
3. Regulatory compliance: Countries may have different regulatory frameworks for using new
technologies. Therefore, obtaining the necessary permits and approvals for the use of CMA may be
challenging.
4. Training and capacity building: CMA requires specialized equipment and expertise. Highway
authorities may need to invest in training and capacity-building programs to equip their workforce
with the necessary skills and knowledge to handle this technology.
5. Supply chain issues: The supply chain for CMA materials may not be well-developed in some
countries, leading to delays and higher costs for acquiring the required materials.
4.2 Technical Challenges
In addition to administrative and logistical challenges, the use of CMA pavement can also pose several
technical challenges. Some of these challenges include:
1. Mix design: Cold mix asphalt requires a specific mix design that can vary depending on the
application and climate conditions. Developing a mix design that meets the performance
requirements can be challenging, especially if there is a lack of experience or expertise in the
country [42].
2. Shorter lifespan: One of the main challenges of CMA is its relatively shorter lifespan compared to
HMA, whereas studies have shown that the CMA pavements last for shorter periods [43].
3. Curing time: CMA requires more time to cure than HMA. In some cases, the curing time may take
several days, leading to longer road closures and disruptions [35].
4. Performance: CMA may not perform as well as HMA in terms of strength, durability, and resistance
to deformation. Its lower strength and stiffness, compared to HMA, can affect its durability and
resistance to deformation. Several studies have shown that CMA pavements have lower stiffness
and elastic modulus compared to HMA pavements [44-46]. This reduced strength can lead to
premature failure and increased maintenance costs.
5. CMA can vary significantly in composition, quality, and performance, leading to inconsistent
performance and reduced pavement life [47,48].
6. Maintenance and repair: Maintenance and repair of CMA pavements can also be challenging,
leading to increased costs and disruption of traffic flow [49].
7. Climate conditions: Cold-mixed asphalt may not perform well in extreme climate conditions, such
as very cold or very hot weather. Therefore, it may not be suitable for some countries with such
climates.
8. Testing and evaluation: CMA requires specialized testing and evaluation procedures to ensure
that it meets the required performance standards. Highway authorities may need to invest in
testing equipment and establish testing protocols to evaluate the performance of CMA.
Addressing the challenges associated with CMA and improving its adoption as a pavement solution
requires a coordinated effort between the public and private sectors, including policymakers, industry
stakeholders, and academia. Further research is needed to develop improved CMA formulations and
manufacturing processes and identify the most effective applications for CMA as a pavement solution.
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Additionally, maintenance and repair strategies are needed to improve the durability and lifespan of CMA
pavements.
5. ADVANCEMENTS IN COLD MIX ASPHALT TECHNOLOGY
In recent years, significant advancements in CMA technology have been aimed at improving its
performance and durability. These advancements have focused on using bio-based additives, recycled
materials, new binders, and production methods. One promising advancement in CMA technology is the
use of additives derived from natural or by-product sources such as lime, cement, fly ash, etc. These
additives show improvements in performance and durability, as well as reduce their environmental impact
[35,50,51]. CMA technology is advanced by using recycled materials, such as recycled asphalt pavement,
as a substitute for virgin materials. This reduces waste and environmental impact and lowers the cost of
CMA production[52, 53]. Additionally, researchers have explored the use of new binders, such as bio-oil,
as a substitute for petroleum-based binders. Bio-oil is a renewable and sustainable alternative that
improves CMA’s performance and durability. Table 2 summarizes previous studies that were carried out
on improving CMA characteristics using various methods.
Table 2: Recent studies on improving cold mix asphalt characteristics.
Year
Authors
Materials Used
Enhancement in Performance
Remarks
2005 Asi and
Assaad[54] Use Jordan oil shale ash improved the mix resistance to
moisture damage
Jordan oil shale ash is
Fly ash that can be
generated through the
direct combustion of
Jordanian oil shale.
2007 Chavez et
al.[55]
Use 1% dose of polyvinyl
acetate additives with
Cationic (Quick setting)
emulsion
increases 31% compressive
strength
Polyvinyl acetate should
be added in dry form
2009 Borhan et al.[56]
Use cylinder oil (CO)
CO improved the properties of
CMA
/
2011 Bocci et al. [57]
Use CMA with 3% cationic
emulsion, 2% cement, and
50% recycled aggregate
In comparison to HMA mixture,
the fatigue life is typically reduced
in CMA due to the higher cement
content and lower residual
bitumen content present in the
mixture.
/
2012 Al-Busaltan et
al. [46]
Use CMA with 50% fly ash
(LJMU- FA1) as a
replacement filler.
Use 50% LJMU- FA1 Increases
the stiffness modulus by 9 times
and Increases 26 times
permanent deformation
resistance
/
2014 Al-Hdabi et al.
[58]
Use 3% waste fly ash and
1% silica fume with Cationic
setting emulsion
The use of waste fly ash and
silica fume in CMA can achieve
similar stiffness as 125-pen hot-
rolled asphalt.
/
2016 Babagoli et al.
[59]
Use polymer-modified
emulsion with lime and
cement
Incorporating cement, lime, or
polymer-modified emulsion led to
a decrease in permanent
deformation.
The emulsion used is
a
slow-curing emulsion.
2016 Gomez-Meijide
and Perez [60]
Use 100% recycled
aggregate
Replacing natural aggregates
with recycled aggregates in CMA
resulted in an increase in ITS by
12.8%
/
2016 Ojum and Thom
[61]
Use RAP (20 mm pen, 5mm
pen) with Cationic emulsion
(Slow setting)
Using RAP in a cold mix
produces superior results
compared to using only virgin
aggregate, and it is even more
cost-effective.
/
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Table 2: Continued.
Year
Authors
Materials Used
Enhancement in Performance
Remarks
2017 Rezaei et al.
[49]
Use CMA with different
materials as a dense-
graded (DG) or open-
graded (OG) aggregate
mixture.
▪
DG Mixes with DG, which contain
different bitumen contents,
consistently showed lower rutting
values compared to mixes with an
OG one.
DG mixtures exhibit higher stiffness
and lower workability compared to OG
mixtures.
Use Cutback
bitumen
2017 Juntao Lin
et al. [62]
Use CMA with 3.5%
cationic slow setting
emulsion, 2% cement, and
100%recycled aggregate.
Extending the curing time can improve
the fatigue life of a material by
augmenting the effective asphalt
content and decreasing the amount of
air voids present.
Use different
curing
protocol.
2017 Dulaimi et al.
[63]
Use alkali-activated (NaOH
solution) with cementitious
filler-containing high-
calcium FA
increment in mechanical properties
and moisture resistance of CMA /
2018 Xiao et al. [38] Use 1 to 2% cement
The overall effectiveness and strength
of the cold mix were improved, as
evidenced by enhanced stiffness
(ITSM), greater resistance to creep,
and increased early strength.
/
2018 Shanbara et
al. [3] Use jute and coir fibers
The mechanical properties of cold mix
asphalt were enhanced, resulting in
improved overall performance.
/
2018 Lian et al. [64]
Use Dense-graded CMA
with Modified emulsion or
addition of cement
Improve the moisture resistance of
CMA
Use CSS-1 h
(Cationic
emulsion)
2019 Kadhim et al.
[65]
use crushed waste glass
has a comparable
gradation to virgin fine
aggregate, with a Nominal
Maximum Aggregate Size
(NMAZ) of 2.36mm.
adding crushed glass (up to 100%) as
a fine aggregate led to the
development of a new CBEM with
mechanical and durability properties
that exceed those of traditional HMA.
/
2021 Lu et al. [66]
Use CMA containing 2%
OPC, 1% FA, and 1%
GGBS
The use of blended cementitious fillers
in CMA exhibits superior stiffness,
reducing the amount of air voids, and
improving the bonding interface
between the aggregate and asphalt
matrix.
/
2021 Al-Kafaji et al.
[67]
Use CMEA containing both
ordinary Portland cement
(OPC) and an acrylic (AR)
polymer.
the addition of OPC and AR improves
water damage resistance. The CBEM
using a blend of OPC and 1.25% AR
displayed the most favorable results
with a 12% increase in resistance
compared to HMA.
/
2022 Dulaimi et al.
[68]
Use CMA with paper
sludge ash (PSA) and
cement kiln dust (CKD)
The stiffness of a mixture that includes
high-calcium fly ash is 27 times greater
than that of the reference mixture.
/
2023 Al Nageim et
al. [69]
Incorporating wastewater
sludge fly ash (UFA) and
bottom ash (UBA) CMA
mixture.
▪ At 3 days of age, using CMA with
2.1% OPC and 3.9% UFA resulted in
ITSM values that were 11 times
higher than traditional CMA.
▪ At 28 days of age, the use of CMA
with the same percentage of OPC
and a lower percentage of UFA
(3.3%) and an additional 0.6% UBA
resulted in ITSM values that were 5
times higher than traditional CMA.
/
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6. CASE STUDIES: SUCCESSFUL APPLICATIONS OF COLD MIX ASPHALT
CMA has been successfully used in various applications, including pothole repairs, patching, and
overlaying worn-out pavements. One case study published in the International Journal of Emerging
Technologies and Innovative Research described the successful application of CMA for repairing potholes
in rural roads in India. The study found that cold mix asphalt was a cost-effective and environmentally
friendly solution that could be easily applied using manual labor and minimal equipment [40]. In another
case study, cold mix asphalt was used to repair Alaska airport runways. The study found that CMA
provided a durable and long-lasting solution for repairing the runways in harsh weather conditions[70].
These case studies demonstrate the versatility and effectiveness of CMA in various applications,
highlighting its potential as a cost-effective and sustainable pavement maintenance and rehabilitation
solution.
In the United Kingdom, a park-and-ride construction scheme was supplied with material during the
spring of 2008. The project had two objectives: to showcase the speed of laying and the ability of the
CMAs to withstand sideways forces from buses in a turning circle. The material's stability under site traffic
conditions allowed for the construction of a second layer much sooner than what could be achieved with
HMA. This was seen as a significant advantage. Figures 5a and 5b depict the turning circle during
construction and after three years [71].
(a) (b)
Figure 5: a: Construction of the bus turning circle, b: Bus turning circle 3 years after construction[71].
Transport Scotland granted permission to trial the CMA material on the A90, making it the first known
use of this material on a UK trunk road. The traffic counts on this road indicated 19,500 vehicles per day,
of which 15% were multi-axle HGV vehicles. The targeted section for reconstruction was 800 meters long
and had previously been designed with 260 mm of HMA base course. This was substituted with 300 mm
of CMA, as depicted in Figure 6 [71].
Figure 6: Application of cold mix asphalt on A90 trunk road site before compaction [71].
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7. FUTURE TRENDS AND POTENTIAL DEVELOPMENTS IN COLD MIX ASPHALT TECHNOLOGY
CMA technology has been gaining popularity as a sustainable and cost-effective pavement solution.
However, this field still has much room for improvement and development. This section displays relatively
deep discussions of some of the future trends and potential developments in CMA technology.
1. Improved Durability and Performance: One of the main challenges of CMA is its relatively lower
durability and performance compared to HMA. Researchers and engineers continuously work to
improve CMA's durability and performance by developing new mix designs, incorporating additives
and modifiers, and using advanced testing methods. The aim is to develop a CMA that can provide
a similar level of performance and durability as HMA.
2. Increased Use of Recycled Materials: CMA technology is already considered a sustainable solution
due to its lower energy consumption and lower emissions compared to HMA. However, there is still
a lot of potential for increasing the sustainability of CMA by incorporating more recycled materials,
such as reclaimed asphalt pavement (RAP), recycled concrete aggregate (RCA), and other waste
materials. Using recycled materials can reduce the need for virgin aggregates and the environmental
impact of CMA production [72].
3. Development of New Binders: The binder is one of the key components of asphalt mixtures, and its
properties can significantly affect the performance and durability of the pavement. Traditional
binders, such as asphalt cement, have limitations in terms of their low-temperature performance,
aging, and susceptibility to moisture damage. Researchers are exploring new binder technologies
such as bio-based binders, polymer-modified binders, and recycled binders to improve the
performance and sustainability of CMA.
4. Advancements in Production and Placement: The production and placement of cold mix asphalt can
be challenging due to its low-temperature properties and lack of workability. Advancements in
production and placement techniques, such as foamed asphalt technology and additives, can
improve the workability and performance of cold-mixed asphalt. These advancements can also lead
to faster construction times, lower construction costs, and reduced environmental impact.
5. Integration with Intelligent Transportation Systems: Intelligent Transportation Systems (ITS) are
advanced technologies that can improve transportation systems' safety, efficiency, and
sustainability [73]. Integrating CMA with ITS can enable real-time monitoring of pavement
conditions, predict maintenance needs, and optimize pavement management strategies. This
integration can also lead to more sustainable pavement solutions by reducing the need for frequent
maintenance and rehabilitation.
8. CONCLUSIONS
The current CMA technology is still under development according to research and industrial practice,;
surveying the updated publications refer to the following as a main conclusion:
• CMA is a promising solution for sustainable and cost-effective pavement construction and
maintenance.
• CMA offers many benefits, including reduced energy consumption, lower emissions, and improved
working conditions for workers.
• CMA technology faces challenges and limitations in terms of its performance and durability.
• The future of CMA technology looks promising, with ongoing research and development focused
on improving production and placement techniques, developing new binders and additives, and
integrating CMA with intelligent transportation systems.
• Further research and development will be essential to address these challenges and ensure that
CMA continues to meet the evolving needs of the transportation industry and society.
• Overall, the potential benefits of CMA for sustainable and cost-effective pavement solutions are
clear, and its future is bright.
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