Previous Article in Journal
Application of Radar for Diagnosis of Defects in Concrete Structures: A Structured Image-Based Approach
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
CivilEng
Volume 6
Issue 3
10.3390/civileng6030046
civileng-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
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Mechanical Properties and Microstructure of High-Performance Cold Mix Asphalt Modified with Portland Cement

by
Anmar Dulaimi
1,2,*,
Yasir N. Kadhim
1,
Qassim Ali Al Quraishy
3,
Hayder Al Hawesah
4,
Tiago Pinto Ribeiro
5 and
Luís Filipe Almeida Bernardo
6,*
1
Department of Civil Engineering, College of Engineering, University of Kerbala, Karbala 56001, Iraq
2
School of Civil Engineering and Built Environment, Liverpool John Moores University, Liverpool L3 2ET, UK
3
College of Engineering, University of Warith Al-Anbiyaa, Karbala 56001, Iraq
4
University Centre, Wigan & Leigh College, Wigan WN1 1RS, UK
5
Paterson & Cooke (UK) Ltd., Wheal Jane Earth Science Park, Baldhu, Cornwall TR3 6EE, UK
6
Department of Civil Engineering and Architecture, University of Beira Interior, 6201-001 Covilhã, Portugal
*
Authors to whom correspondence should be addressed.
CivilEng 2025, 6(3), 46; https://doi.org/10.3390/civileng6030046
Submission received: 11 July 2025 / Revised: 10 August 2025 / Accepted: 20 August 2025 / Published: 27 August 2025
(This article belongs to the Section Construction and Material Engineering)
Browse Figures
Versions Notes

Abstract

The use of hot mix asphalt (HMA) has several drawbacks, such as the emission of harmful gases into the atmosphere, difficulties in maintaining temperature over long distances, and the requirement for high energy consumption during preparation and installation. In order to solve these issues, this research aimed to produce High-Performance Cold Mix Asphalt (HP-CMA), in which Ordinary Portland Cement (OPC) is used as a filler to replace limestone filler at 0%, 1.5%, 3%, 4.5%, and 6% of the aggregate weight. Indirect Tensile Stiffness Modulus (ITSM), moisture susceptibility, temperature susceptibility, and microstructural analysis tests were carried out. The results showed that the ITSM was considerably enhanced when OPC was utilized. When comparing HP-CMA with 3% OPC to the control HMA (100–150 pen), the ITSM increased by approximately 80% after three days. In contrast, HP-CMA with 4.5% OPC achieved the same ITSM as the control HMA (40–60 pen) after seven days. Moreover, the ITSM of the HMA 40–60 pen decreased by 91.93% when the temperature rose from 20 °C to 45 °C, whereas the ITSM of the HP-CMA with 6% OPC decreased by 42.47% over the same temperature range. This suggests that HP-CMA is more stable than the HMA 40–60 pen at elevated temperatures. The superior performance of the HP-CMA can be attributed to two essential factors: the improved binding effect due to the demulsification of the asphalt emulsion used as a binder, and the formation of hydration products from the added cement.

1. Introduction

The primary requirements for the current development of the road industry on a global scale are cost effectiveness and environmental sustainability [1,2]. According to Abdulrahman, et al. [3], the sector that uses the most energy is road construction. Road transportation alone accounts for 72% of the total greenhouse gas emissions within the transportation sector [4]. Typically, high temperatures ranging from 150 °C and 180 °C are used to manufacture hot mix asphalt (HMA), a type of traditional pavement. Owing to the high energy consumption associated with this requirement, it is costly and significantly contributes to greenhouse gas emissions [5]. Therefore, academics are focusing more on energy consumption and improving environmental protections to ensure sustainability and cost effectiveness, as these are the two main issues facing the global road sector [6]. To address these economic and environmental concerns, new low-carbon technologies, such as cold mix asphalt (CMA), are being used worldwide in road construction. CMA, which uses bitumen emulsions as a binder, outperforms HMA technology in terms of energy consumption, economic effectiveness, and environmental friendliness [2,7].
CMA, which uses bitumen emulsions as a binder, outperforms HMA technology in terms of energy consumption, economic effectiveness, and environmental friendliness [2,7]. However, some studies highlighted specific weaknesses of CMA in comparison with conventional HMA, including its lower strength, higher air void content, and longer curing time [8,9]. It was reported that water in the CMA mix contributes significantly to suspending the strength improvement of the mix throughout the curing period [10]. So, CMA is typically limited to surface treatments and the maintenance of road pavement, such as pothole repairs and patching [11]. This means that the above limitations restrict the CMA use in high-grade road layers or high-performance roads. In this study, the term “high-performance” is used to denote the significant improvements in mechanical strength, stiffness, and microstructure achieved through Portland cement modification. These enhancements, as demonstrated in the experimental results, exceed those typically reported for conventional CMA in the literature, enabling its potential application in higher-grade pavement layers.
HMA is widely used in pavement construction due to its well-established performance and load-bearing capacity. However, its production and placement require high temperatures (typically 140–180 °C), which results in high energy consumption, increased production costs, and significant greenhouse gas emissions. Moreover, the need for high-temperature compaction limits HMA’s suitability for remote locations or situations requiring rapid, low-temperature construction. In contrast, CMA can be produced and placed at ambient temperatures, offering clear environmental and logistical advantages. These include lower energy demands, reduced emissions, improved safety for workers, and the potential for staged construction without reheating. Nevertheless, CMA has traditionally exhibited lower early strength, slower curing rates, and higher moisture susceptibility compared to HMA, which has limited its use in high-performance pavement layers. Addressing these shortcomings is essential to unlocking CMA’s full potential for sustainable infrastructure applications [12].
HP-CMA, as developed in this study, is designed to overcome the performance limitations of conventional CMA by incorporating Portland cement. This modification promotes the formation of cement hydration products, which accelerate strength development, reduce air voids, and enhance stiffness, moisture resistance, and temperature stability. While conventional CMA is typically limited to low-volume or temporary pavement applications, HP-CMA offers mechanical and durability characteristics suitable for more demanding service conditions, including higher traffic loads and longer design lives.
Unlike HMA, CMA is manufactured and applied at ambient temperature [13]. The emulsified binder used in CMA has a lower binder viscosity, which results in a sixfold decrease in the energy required compared to HMA [14]. The physical properties of the bitumen binder used in emulsions can be modified to address the performance limitations of CMA.
Recently, CMA mixtures have garnered increasing attention from researchers. Three types of cold-mixed asphalt binders—solvents, foams, and emulsifiers—have been thoroughly studied by Thanaya [15] for their influence on the performance of CMA mixtures. Based on these results, the emulsified asphalt binder was found to be the most compatible with CMA, and the key factor influencing its construction workability and road performance was its adherence to mineral materials. The addition of cement can considerably enhance an emulsified asphalt mixture’s high-temperature performance and water stability, but it negatively impacts the mixture’s low-temperature performance, according to Xiao, et al. [16].
Cement-emulsified asphalt mortar (CEAM), which has high fluidity, low energy consumption, and effective construction performance, was created by researchers to address this issue [17]. The necessary toughness in the CEAM system is provided by the demulsification of emulsified asphalt, whereas the necessary strength is provided by cement hydration [18]. The cement component most frequently used in the CEAM system is Ordinary Portland Cement (OPC), which has a slow hardening time and generates significant carbon emissions [17]. With an asphalt-to-cement (A/C) ratio of 0.35, Shi, et al. [19] produced CEAM using calcium sulfoaluminate cement, a rapidly hardening cement component with a setting time of 210–250 min and a 1-day compressive strength of 4.5–5.0 MPa. A cement-emulsified asphalt mix is prepared by mixing emulsified asphalt and aggregates at room temperature with cement. To create a new engineering material, the cement hydrates, crystallizes, and solidifies in combination, while the emulsified asphalt aggregates and demulsifies [16]. While emulsified asphalt is liquid at room temperature, demulsification occurs when it is mixed, paved, and compacted with aggregate and cement [20]. A portion of the moisture generated during demulsification is utilized by the cement hydration process, whereas the other portion dissipates through evaporation. The interaction between the cement and asphalt emulsion can significantly affect the demulsification process of the asphalt emulsion. The process of asphalt droplet flocculation, coalescence, and subsequent asphalt film production is accelerated by cement–asphalt adsorption and asphalt emulsion destabilization [21]. Mercado, et al. [22] reported that the demulsification mechanisms of asphalt emulsion are primarily divided into two groups when combined with solids: The first mechanism is the coalescence of droplets generated from the destabilization of the asphalt emulsion, followed by adhesion to the solid surface. The second mechanism initiates with the droplets first adhering to the solid surface, after which, coalescence occurs. Ouyang, et al. [23] showed that although both phases are essential demulsification behaviours, the droplet’s direct adherence to the cement surface dominates the mixing process due to the cement’s potent adsorption capacity.
Energy consumption and carbon emissions during construction are significantly reduced because the asphalt and aggregate heating process is avoided, thereby preventing the emission of asphalt smoke associated with heating [24]. As a result, the use of cement–emulsified asphalt in civil engineering, particularly in pavement engineering, has increased steadily. The attributes of a cement-emulsified asphalt mixture fall between those of cement and emulsified asphalt, as it combines two materials with different technical characteristics [25].
Owing to their numerous uses in the fields of asphalt pavement maintenance and repair [26], cement asphalt emulsion mixtures (CAEMs) have garnered significant attention in contemporary civil engineering [27]. The modulus and physical characteristics of CAEM, an inorganic–organic composite [28], fall between those of cement concrete and asphalt mixtures. According to Ayar Ayar [29], Castañeda López, et al. [30], Ouyang, et al. [31], and others, CAEMs combine the benefits of cement concrete and asphalt mixtures, with compressive strength comparable to that of cement concrete and flexibility comparable to that of asphalt mixtures. To optimize material design, recent global efforts have focused on improving the strength and curing process of CAEMs [32,33]. Examples of these efforts include adjusting aggregate gradations [34] and the A/C ratio [35]. It has been reported that the early-age strength of CAEMs can be enhanced by cement through the production of cement hydrates and the acceleration of asphalt emulsion demulsification [36]. Cement has also been shown to act as an inorganic filler. Furthermore, research findings suggest that the primary cause of the enhanced microstructure observed in CAEMs is increased pore homogeneity [37]. In addition to improving the resistance of the CMA mixture to rutting, fatigue, and water susceptibility, Dulaimi, et al. [38] also significantly decreased its temperature sensitivity. When creating a CMA mixture, Ling and Bahia Ling and Bahia [39] suggested a mixing technique to ensure blend homogeneity between the aggregate and emulsified bitumen. Building on efficient compaction operations, Zhang, et al. [40] developed a prediction model for the compaction process of cement-emulsified asphalt mixtures. As previously stated, nonetheless, the aforementioned CMA mixture is unable to meet the performance requirements of high-grade road structural layers.
The goal of the present study is to develop and evaluate a HP-CMA modified with Portland cement, with the aim of overcoming the common limitations of conventional CMA and enabling its potential use in higher-grade pavement layers. The performance of the proposed mixtures is assessed through Indirect Tensile Stiffness Modulus (ITSM), moisture susceptibility, temperature susceptibility, and microstructural analyses. These tests were selected to provide a focused assessment of the material’s mechanical strength, resistance to moisture damage, and thermal stability. It should be noted that this study was designed with a primary focus on these parameters, as they were the key performance indicators targeted in the initial phase of the research.

2. Methodology

2.1. Materials

In this work, crushed granite aggregate, which is commonly used to produce hot mix asphalt concrete, was used. As per BS EN 13108-1 [41], the aggregate grade corresponded to a 14 mm asphalt concrete surface course. After the aggregate was sieved in accordance with BS EN 933–1 [42], it was riffled, dried, bagged, and then re-sieved (see Table 1). The aggregate properties are presented in Table 2. This study used a slow-setting cationic emulsion (supplied by Jobling Purser, Newcastle, United Kingdom) designated CAB50, based on a 50 penetration-grade bitumen, (Table 3). The 100/150 and 40/60 penetration grades were employed for HMA. Traditional limestone filler (TLF) was obtained from Francis Flower in the United Kingdom.

2.2. Sample Preparation and Conditioning

The process and preparation for cold bitumen emulsion mixtures comprise the following steps: determining the aggregate gradation, defining the initial residual bitumen content (IRBC) and initial emulsion content (IEC), and determining the premixing water content (PMWC). These steps were established following the Asphalt Institute MS-14 design procedure [48], which estimates IEC from the target residual bitumen content, the emulsion’s bitumen content, and the aggregate’s absorption capacity.
The IRBC was calculated using the empirical equation suggested by MS-14 [48]. This equation is as follows:
P = (0.05A + 0.1B + 0.5C) × 0.7
where P: the percentage of initial residual bitumen content by the total weight of dried aggregate; A: the percentage of aggregate retained on a 2.36 mm sieve; B: the percentage of aggregate passing through a 2.36 mm sieve but retained on a 0.075 mm sieve; C: the percentage of aggregate passing through a 0.075 mm sieve.
The value of P was calculated to be 6.16%. The IEC was determined by dividing P by the percentage of bitumen content in the emulsion as below:
IBEC (%) = P/X
where X: the bitumen content of the emulsion, 50%; IEC = 6.16/0.5 = 12.32% of aggregate weight, which is rounded to be 12.5%. In this study, the IEC is consistent with values reported for dense-graded cold mix asphalt and cationic slow-setting emulsions [13,49].
The coating of aggregates by the bitumen emulsion is effectively controlled by the PMWC. The fine particles ball in the bitumen, resulting in an undesirable coating when insufficient pre-wetting water applied. The coating test as per the MS-14 [48] was performed to determine the PMWC. Various samples of aggregate and emulsion mixes were prepared, keeping the same quantity of bitumen emulsion content (as calculated by Equation (2)), with variable water content. Five percentages of pre-wetting water content—2.5%, 3%, 3.5%, 4% and 4.5% of the total weight of aggregate—were examined, and the aim was to select the lowest pre-wetting water content that ensured the maximum coating of aggregates, where the mix was neither too sloppy nor too stiff. According to visual assessment, 3% was selected as the PMWC.
The PMWC was determined from the aggregate’s water absorption and the workability of the mixture during blending, yielding an optimum value of 3%, which falls within the 2–4% range recommended by MS-14 [48] for comparable aggregate types.
According to BS EN 12697-26 [50], the ITSM test is used to evaluate the stiffness of asphalt mixtures, particularly their resistance to deformation under indirect tensile loading. OPC, in various percentages by aggregate weight (0%, 1.5%, 3%, 4.5%, and 6%), was used to prepare the HP-CMA samples. These percentages correspond to limestone filler replacements of 25%, 50%, 75%, and 100% by filler weight, not the total aggregate weight. The performance of these mixtures was compared with that of standard HMA containing limestone filler. Each sample, for both cold and hot mixes, was prepared using a Marshall compaction hammer.
In the laboratory, samples of HP-CMA and HMA were combined and compacted at 20–25 °C and 160–170 °C, respectively. Using a Hobart mixer, the aggregate and filler material were combined with prewetting water (3% by weight of the aggregate) and mixed slowly for one minute. After a 30 min rest period, the bitumen emulsion (12.5% by weight of the aggregate) was added at the same low speed (approximately 72 RPM), and mixing continued for an additional two minutes. Thus, a total of three minutes was required to fully mix the bitumen emulsion and prewetting water. The mixture was then placed into the mold using a spatula and manually compacted. Finally, the mold containing the mixture was compacted using a standard Marshall hammer (impact compactor), with 50 blows applied to each face of the specimen. At a temperature of 20 °C, the 100 mm diameter samples were subsequently allowed to cure in their molds for 24 h. Following curing, the samples were extruded using a hydraulic demoulding apparatus.
Two steps were involved in the sample conditioning for ITSM testing: In accordance with the Asphalt Institute technique, the samples were kept in the mold for one day to prevent specimen disintegration, which constituted the initial conditioning stage. For the second stage, the samples were demoulded the next day and kept in a vented oven at 40 °C for an additional day. In compliance with BS EN 12697–26 [50], the samples required for indirect tensile stiffness testing were extruded and tested at 3, 7, 28, and 56 days of age after remaining in their molds in the laboratory for 24 h at a temperature of 20 °C. For each test condition, the average values of three samples were used as the basis for all reported results. Table 4 provides detailed compositional information for all mixes.

2.3. Testing Programme

Figure 1 shows the methodology adopted in this study.

2.3.1. Indirect Tensile Stiffness Modulus (ITSM) Test

According to Li, et al. [51] and Jiang, et al. [52], asphalt pavements are susceptible to surface distress caused by rutting, fatigue cracking, thermal cracking, and moisture damage, when subjected to significant traffic loads. The stiffness of the asphalt mixture at moderate temperatures was evaluated via the Indirect Tensile Stiffness Modulus (ITSM) method (BS EN 12697-26). The ITSM quantifies mixture stiffness and structural support. In general, the ITSM test was applied to evaluate stiffness performance. In accordance with BS EN 12697-26 [50], the test was conducted using the Cooper Research Technology HYD 25 testing apparatus. Each sample measured 100 ± 3 mm in diameter and 63 ± 3 mm in height. The testing conditions for the ITSM procedure are listed in Table 5.

2.3.2. Moisture Susceptibility Test

Moisture susceptibility is a characteristic of bitumen mixtures that reflects their ability to withstand damage caused by water. Accordingly, the resistance of HP-CMA to moisture damage was assessed. The European Committee for Standardization [53] specifies that test samples for moisture susceptibility should measure 100 mm in diameter and 62.5 mm in thickness. Eight samples were prepared and divided into two groups. In the first group, laboratory-made samples were left in their molds for one day before being removed and allowed to dry for seven days at 20 °C. In the second group, the samples were removed from the molds the next day and cured in the laboratory at 20 °C for four days. Following EN 12697-26 [50], the samples were submerged in water for 30 min, placed under vacuum at an absolute pressure of 6.7 kPa, and then submerged in water at 40 °C for three days. The ratio of the stiffness modulus after conditioning to the stiffness modulus prior to conditioning, or the Stiffness Modulus Ratio (SMR), was calculated to evaluate moisture sensitivity. Once the samples had been vacuumed for 30 min at 6.7 kPa, they were partially submerged in water and conditioned in water at 40 °C for 72 h. They were then held for four days in the laboratory. The ITSMs of all the samples, both conditioned and unconditioned, were measured at 20 °C. The samples were subsequently held for 96 h in the laboratory. After that, the conditioned samples’ ITSM values could be computed. The formula SMR = (wet ITSM/dry ITSM) × 100 was used to calculate the SMR.

2.3.3. Temperature Susceptibility Test

The ITSM test was also adopted to assess the temperature resistance performance of asphalt mixtures under environmental and loading conditions that simulate real field conditions. Three samples of each mixture type were used under loading conditions at temperatures of 5 °C, 20 °C, and 45 °C.

2.3.4. Microstructure Measurements

The morphology of the CMA was examined via SEM–EDS analysis using a Quanta 200 microscope equipped with an EDX Oxford INCA X-Act sensor, operated at an accelerating voltage of 5–20 kV. Prior to testing, the sample surfaces were coated with a thin layer of gold or platinum to improve conductivity.

3. Results and Discussion

3.1. Effect of OPC Addition on the ITSM Results

ITSM tests were conducted to evaluate the resistance of asphalt mixtures to tensile fracture failure. Figure 2 presents the results of adding OPC to HP-CMA mixtures prepared with different percentages of OPC at various curing times, compared with the control mixtures. As shown in Figure 2, the stiffness rate of the HP-CMA mixtures at early ages clearly increased with higher OPC content. For all the HP-CMA mixtures containing OPC—especially at higher doses—the ITSM increased significantly with curing time due to the chemical activity of the OPC. In contrast, the control mix showed only minor changes in the ITSM over time. After only three days, the ITSM of HP-CMA with only 1.5% OPC increased by approximately ten times compared with that of the control mixture. Both curing duration and OPC content influenced ITSM development, with the rate of strength gain varying for each mix type. Across all the curing periods, the ITSM values of the 3%, 4.5%, and 6% OPC mixtures were greater than those of the soft HMA mixtures, except for the 0% and 1.5% OPC mixtures, which had the lowest ITSM values among all HP-CMA mixtures. The mixtures with 3% OPC at all curing ages and 4.5% OPC at 3, 7, and 28 days exhibited ITSM values higher than those of the soft HMA mixture, but lower than those of the hard HMA mixture. Meanwhile, 4.5% OPC at 28 and 56 days, and 6% OPC at all curing ages, produced greater stiffness than both HMA mixtures. This suggests that, under static stress, mixtures with cement have greater tensile strength at failure. Additionally, the modified mixtures appear capable of withstanding higher tensile stresses before breaking [54]. The ITSM of the control 0% OPC mix after 56 days was 566 MPa, whereas the 1.5% OPC mix reached 1023 MPa, confirming a more than twofold increase Additional enhancements were detected with elevated OPC content: 3% OPC reached 3954 MPa, 4.5% OPC achieved 5126 MPa, and 6% OPC peaked at 7000+ MPa, approaching and even becoming superior to the traditional HMA mixes (e.g., HMA 40/60 at approximatively 4450 MPa and HMA 100/150 at approximatively 1500 MPa).
Although the ITSM provides a standardized stiffness metric for both CMA and HMA, these materials differ fundamentally in composition, microstructure, curing behavior, and performance objectives. CMA incorporates a hydraulic binder (cement) and is intended for applications where cold placement and staged strength gain are advantageous, whereas HMA is a thermoplastic mixture compacted at high temperatures to achieve immediate load-bearing capacity. Consequently, the ITSM values are not intended to imply direct interchangeability of these materials in all applications, but rather to provide a comparative indication of stiffness performance under the tested conditions.
The improvement in ITSM is attributed to the hydraulic reaction of OPC. This reaction reduces the water content in HP-CMA through the hydration process of the secondary cementitious filler (SCF), decreases the void content —as in conventional CMA—and generates hydration binding products (mortar paste) that bond the internal ingredients of HP-CMA together. According to Dołżycki, et al. [55], the demulsification of bitumen emulsions is accelerated in the presence of cementitious components, which can increase the strength of HP-CMA. These results are in agreement with those reported by Dołżycki, Jaczewski, and Szydłowski Dołżycki, Jaczewski and Szydłowski [55] and Habeeb and Al-Hdabi Habeeb and Al-Hdabi [49].
The interfacial bonding between asphalt emulsion and cement hydration products significantly contributes to the increased stiffness of the mixture, further supported by microstructural interactions among the aggregates, binder, and filler.

3.2. Effect of OPC Addition on Moisture Susceptibility

Figure 3 shows the cold mix-conditioned ITSM, unconditioned ITSM, and SMR. For comparison, the moisture susceptibility of HMA mixtures was also evaluated. Following conditioning, the ITSM of HP-CMA showed minimal variation. While most mixes experienced a decrease in ITSM after water conditioning, the ITSM for the 4.5% and 6% OPC mixes exhibited an increase. The ITSM values of the 3%, 4.5%, and 6% OPC mixtures—both conditioned and unconditioned—were consistently above the soft HMA thresholds for bituminous mixtures. Before and after conditioning, the 6% OPC mixture achieved the highest ITSM. Its SMR exceeded 100%, surpassing the standard for hard HMA. The SMR improved steadily with increasing OPC content, from 73% at 0% OPC to approximately 96%, 97%, 101%, and 102% for 1.5%, 3%, 4.5%, and 6% OPC mixes, respectively. This trend indicates the improved moisture resistance of CMA modified with OPC, with the 6% OPC mix surpassing 100%, demonstrating enhanced performance after conditioning. In light of these results, there is little concern regarding the moisture susceptibility of the HP-CMA mixture containing 6% OPC. Compared with the control mixture, the use of OPC improved the degree of bonding between the coarse aggregates. This improvement occurs because mixtures containing OPC react with water trapped in the bituminous emulsion to form hydration products. When samples are submerged in water, the hydration process is accelerated, producing a mixture with a stronger internal microstructure and greater resistance to moisture damage [56]. Consequently, increasing the proportion of OPC not only meets the specifications for this specific test, but also enhances performance in terms of moisture susceptibility. These results are consistent with the findings of [57].

3.3. Effect of OPC Addition on the Temperature Susceptibility

Asphalt is viscoelastic–plastic material that becomes more susceptible to deformation as temperature increases [58]. This phenomenon increases the likelihood of rutting distress and raises road maintenance costs, particularly under heavy traffic conditions [59,60]. One major issue affecting the successful operation and construction of highways is the low durability of asphalt pavements, with high-temperature stability being a key factor influencing this durability [61]. Asphalt pavement is prone to rutting during warm months when traffic loads are high or concentrated. If rutting area and depth exceed allowable limits, it can lead to early pavement failure or an increased risk of traffic accidents [62].
Figure 4 shows ITSM performance at different testing temperatures. The control mixture with limestone filler failed at 45 °C as a result of the reduced strength of the mixture at high temperatures. The rate of change in ITSM for the HP-CMA mixture was lower than that for both grades of HMA. This indicates that the HP-CMA mixture performs better than traditional HMAs when temperature changes occur. The superior performance of HP-CMA in fluctuating temperatures is attributed to its cement–asphalt composite network. ITSM results demonstrate that HP-CMA maintained more stable mechanical properties across the tested temperature range, while HMA experienced greater stiffness degradation. This improvement in HP-CMA is due to the synergistic effect of hydration products and asphalt emulsion, which enhanced its durability.

3.4. SEM–EDS Observations

The results of the cement paste mixed with asphalt emulsion, which was used to investigate the microstructure of HP-CMA at 3 and 28 days, are shown in Figure 5, Figure 6, Figure 7 and Figure 8. The formation of major hydration products, such as ettringite and calcium silicate hydrate (C–S–H), is highlighted. The highlighted areas were designated as C–S–H based on their distinctive morphological characteristics seen under a scanning electron microscope, particularly the fibrous and foil-like structures, as well as dense masses or clusters of tiny crystals typically associated with C–S–H phases, Additionally, EDS analysis revealed a dominant presence of calcium, silicon, and oxygen in proportions consistent with the known elemental composition of C–S–H. A closer inspection of Figure 5 reveals that certain needle-like crystals had filled the voids created by the evaporation of water during the CMA curing process. Moreover, the original large voids were divided into several small voids, and some crystals even penetrated the asphalt film, suggesting that the interpenetrating network of cement hydrates and asphalt film improved the engineering properties of the mixture. The abundance of needle-shaped ettringite (produced during early-stage hydration) is one of the major traits identified in these SEM images. While ettringite development is typically associated with setting time, early strength is also provided by this hydration product [63,64]. Figure 6 shows that the samples cured for 28 days had a comparatively smaller amount of needle-shaped ettringite. This difference can be attributed to the conversion of ettringite to monosulfate (calcium aluminate monosulfate) over time. A more uniform and denser microstructure with many cement hydrates was created, as shown by the SEM images of the samples. The dense structure resulted from the formation of a network structure by the hydration products and asphalt films, which gave CMA excellent strength. Furthermore, the predominant phase comprising the regular and compact microstructure was C–S–H. Cement grains and asphalt emulsion are distributed in suspension during the first phase of hydration. The continuous asphalt layer is gradually applied to the surfaces of both hydration products and unhydrated cement grains as a result of the demulsification of the asphalt emulsion and the creation of hydration products. Eventually, a cement–asphalt composite network structure is formed [21].
The molecular-level interactions between asphalt emulsion and cement hydration products are responsible for the observed increases in mechanical properties. Cement hydrates produce ettringite and C–S–H gel, both of which contribute to the development of strength. By affecting the dispersion of hydration products and strengthening the bond between the asphalt and the mineral matrix, the asphalt emulsion influences the hydration process.
Figure 7 and Figure 8 show the EDS data for the two distinct gel product morphologies in the hardened samples at 3 and 28 days. At all curing ages, the basic constituent elements identified via EDS were C, O, Ca, Si, and Al, with traces of K, S, Mg, and Fe. The irregular protrusions were identified as asphalt particles, according to the EDS analysis. The asphalt emulsion and cement grains are initially scattered in suspension during the first phase of hydration. As the asphalt emulsion demulsifies and hydration products form, a continuous asphalt layer gradually coats the surfaces of both the unhydrated cement grains and hydration products, ultimately forming a cement–asphalt composite network structure. According to Sadique and Al-Nageim [65], the stability and density of the cementitious product are reflected in the calcium content of the C–S–H gel. The figures demonstrate that there was a significant Ca concentration throughout all curing periods, resulting in a very stable C–S–H gel. The raw ingredients were sufficiently hydrated and dissolved to provide high Ca concentrations in the gel products. Further evidence of continuing C–S–H gel formation—which greatly increases the strength of the binder—is the presence of high Ca and Si contents at various curing ages. There is evidence of coarse particle agglomeration, with black patches that the study recognized as carbon and possibly other elements. The EDS data show the presence of aluminum, which suggests the formation of needle-like ettringite. It should be noted that the appearance of platinum (Pt) in the EDS results (Figure 8) is likely due to the platinum coating applied to the sample surface during SEM sample preparation to improve conductivity and imaging quality. In addition, the absence of iron (Fe) in this figure may be attributed to the specific localized area analyzed in this paste sample, which may not have included any iron-bearing phases or particles—unlike the area analyzed in Figure 7, which likely included a portion of the OPC with trace Fe content.

4. Conclusions

The purpose of this study was to investigate the use of varying percentages of OPC to enhance the performance of conventional CMA. Within the scope of the parameters measured in this study (ITSM, moisture susceptibility, and temperature susceptibility), the four novel CMAs demonstrated higher stiffness and favorable moisture and temperature susceptibility compared to traditional HMAs at 3, 7, and 28 days. However, given the fundamental differences in material composition, microstructure, curing behavior, and intended applications, these results should be interpreted as comparative indicators rather than evidence of direct interchangeability. ITSM values were higher in mixtures with 3% OPC at all curing ages and in mixtures with 4.5% OPC at 3, 7, and 28 days, compared to the soft HMA mix. In contrast to both HMA mixtures, the 4.5% OPC mix at 28 and 56 days, and the 6% OPC mix at all curing ages, exhibited greater stiffness. Owing to their enhanced performance over typical HMAs, the results of water sensitivity tests for the four new CMA combinations are promising. Following water conditioning, ITSM increased for the 4.5% and 6% OPC mixtures, whereas it decreased for the other mixes. Under temperature fluctuations, these HP-CMA mixtures demonstrated better performance than conventional HMAs. The OPC participates in hydration processes that accelerate the demulsification of the asphalt emulsion, resulting in a greater quantity of hydration products and a denser, more uniform microstructure. These products consist mainly of needle-like ettringite and amorphous C–S–H gel.
This study was limited to the evaluation of stiffness (ITSM), moisture susceptibility, and temperature susceptibility. Additional performance characteristics—such as rutting resistance, fatigue resistance, compaction behavior, and long-term durability—were not assessed at this stage. These further evaluations will provide a more comprehensive basis for mix design recommendations and practical implementation.
Further research on performance indicators for the developed mixes, including flexural strength and freeze–thaw resistance, is also strongly recommended. These tests are essential for evaluating the durability and long-term performance of HP-CMA in practical applications. One advantage of using HP-CMA in large-scale road construction projects is the ability to mix it on-site, eliminating the need for complex transportation logistics. Furthermore, its installation flexibility allows for easier adaptation to specific site conditions, enabling precise control over the mixing and compaction processes.
In addition, understanding the correlations between ITSM, moisture susceptibility, and temperature stability could offer a more comprehensive assessment of long-term performance under varying ecological and loading conditions. Consequently, future research is recommended to also examine statistical correlations among mechanical and durability indicators and thermal behavior to further enhance the performance of cold mix asphalt.

Author Contributions

A.D.: Conceptualization, methodology, validation, investigation, resources, writing-original draft, writing—review and editing, project administration, supervision, and funding acquisition. Y.N.K.: writing—original draft, writing—review and editing. Q.A.A.Q.: Conceptualization, methodology, writing—original draft, writing—review and editing, project administration. H.A.H.: resources, writing—original draft, writing—review and editing. T.P.R.: Visualization, writing—review and editing. L.F.A.B.: Visualization, resources, writing—review and editing. 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

The authors declare that the data supporting the findings of this study are available within the paper.

Acknowledgments

The authors express sincere gratitude for the support received from Kerbala University in Iraq.

Conflicts of Interest

Tiago Pinto Ribeiro was employed by the company Paterson & Cooke (UK), Ltd. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Anmar Dulaimi, Yasir N. Kadhim, Qassim Ali Al Quraishy, Hayder Al Hawesah and Luís Filipe Almeida Bernardo declare no conflicts of interest.

References

  1. Ansari, A.H.; Jakarni, F.M.; Muniandy, R.; Hassim, S.b.; Elahi, Z. Natural rubber as a renewable and sustainable bio-modifier for pavement applications: A review. J. Clean. Prod. 2021, 289, 125727. [Google Scholar] [CrossRef]
  2. Jain, S.; Singh, B. Cold mix asphalt: An overview. J. Clean. Prod. 2021, 280, 124378. [Google Scholar] [CrossRef]
  3. Abdulrahman, S.; Hainin, M.R.; Idham Mohd Satar, M.K.; Hassan, N.A.; Usman, A. Mechanical performance and global warming potential of unaged warm cup lump modified asphalt. J. Clean. Prod. 2021, 297, 126653. [Google Scholar] [CrossRef]
  4. Fan, Y.V.; Perry, S.; Klemeš, J.J.; Lee, C.T. A review on air emissions assessment: Transportation. J. Clean. Prod. 2018, 194, 673–684. [Google Scholar] [CrossRef]
  5. Dulaimi, A.; Al Nageim, H.; Ruddock, F.; Seton, L. Assessment the Performance of Cold Bituminous Emulsion Mixtures with Cement and Supplementary Cementitious Material for Binder Course Mixture. In Proceedings of the 38th International Conference on Cement Microscopy, Lyon, France, 17–21 April 2016; pp. 283–296. [Google Scholar]
  6. Al-Sabaeei, A.M.; Napiah, M.B.; Sutanto, M.H.; Alaloul, W.S.; Usman, A. A systematic review of bio-asphalt for flexible pavement applications: Coherent taxonomy, motivations, challenges and future directions. J. Clean. Prod. 2020, 249, 119357. [Google Scholar] [CrossRef]
  7. Dash, S.S.; Chandrappa, A.K.; Sahoo, U.C. Design and performance of cold mix asphalt—A review. Constr. Build. Mater. 2022, 315, 125687. [Google Scholar] [CrossRef]
  8. Alenezi, T.; Norambuena-Contreras, J.; Dawson, A.; Garcia, A. A novel type cold mix pavement material made with calcium-alginate and aggregates. J. Clean. Prod. 2019, 212, 37–45. [Google Scholar] [CrossRef]
  9. Thanaya, I.N.A.; Zoorob, S.E.; Forth, J.P. A laboratory study on cold-mix, cold-lay emulsion mixtures. Proc. Inst. Civ. Eng. Transp. 2009, 162, 47–55. [Google Scholar] [CrossRef]
  10. Ziari, H.; Nasiriamiri, E.; Ayar, P. Effect of encapsulated waste oils and compaction method on the curing and strength of cold mix asphalt. Sci. Rep. 2025, 15, 26687. [Google Scholar] [CrossRef] [PubMed]
  11. Shanbara, H.K.; Ruddock, F.M.; Atherton, W. Airfield and Highway Pavements 2017. In Proceedings of the International Conference on Highway Pavements and Airfield Technology 2017, Philadelphia, PA, USA, 27–30 August 2017. [Google Scholar]
  12. Abdel-Wahed, T.; Dulaimi, A.; Shanbara, H.K.; Al Nageim, H. The Impact of Cement Kiln Dust and Cement on Cold Mix Asphalt Characteristics at Different Climate. Sustainability 2022, 14, 4173. [Google Scholar] [CrossRef]
  13. Al Nageim, H.; Dulaimi, A.; Ruddock, F.; Seton, L. Development of a new cementitious filler for use in fast-curing cold binder course in pavement application. In Proceedings of the 38th International Conference on Cement Microscopy, Lyon, France, 17–21 April 2016; pp. 167–180. [Google Scholar]
  14. Day, D.; Lancaster, I.M.; McKay, D. Emulsion cold mix asphalt in the UK: A decade of site and laboratory experience. J. Traffic Transp. Eng. (Engl. Ed.) 2019, 6, 359–365. [Google Scholar] [CrossRef]
  15. Thanaya, I.N.A. Improving the Performance of Cold Bituminous Emulsion Mixtures Incorporating Waste Materials. Ph.D. Thesis, University of Leeds, Leeds, UK, 2003. [Google Scholar]
  16. Xiao, J.; Jiang, W.; Ye, W.; Shan, J.; Wang, Z. Effect of cement and emulsified asphalt contents on the performance of cement-emulsified asphalt mixture. Constr. Build. Mater. 2019, 220, 577–586. [Google Scholar] [CrossRef]
  17. Miljković, M.; Radenberg, M.; Fang, X.; Lura, P. Influence of emulsifier content on cement hydration and mechanical performance of bitumen emulsion mortar. Mater. Struct. 2017, 50, 185. [Google Scholar] [CrossRef]
  18. Liu, B.; Liang, D. Effect of mass ratio of asphalt to cement on the properties of cement modified asphalt emulsion mortar. Constr. Build. Mater. 2017, 134, 39–43. [Google Scholar] [CrossRef]
  19. Shi, J.; Liu, B.; Tan, J.; Dai, J.; Chen, J.; Ji, R. Experimental Studies and Microstructure Analysis for Rapid-Hardening Cement Emulsified Asphalt Mortar. J. Constr. Eng. Manag. Asce 2020, 146, 04020130. [Google Scholar] [CrossRef]
  20. Ouyang, J.; Tan, Y.; Li, Y.; Zhao, J. Demulsification process of asphalt emulsion in fresh cement-asphalt emulsion paste. Mater. Struct. 2015, 48, 3875–3883. [Google Scholar] [CrossRef]
  21. Fang, L.; Zhou, J.; Yang, Z.; Yuan, Q.; Que, Y. Interaction between cement and asphalt emulsion and its influences on asphalt emulsion demulsification, cement hydration and rheology. Constr. Build. Mater. 2022, 329, 127220. [Google Scholar] [CrossRef]
  22. Mercado, R.A.; Sadtler, V.; Marchal, P.; Choplin, L.; Salager, J.L. Heteroflocculation of a cationic oil-in-water emulsion resulting from Fontainebleau’s sandstone powder addition as a model for asphalt emulsion breakup. Ind. Eng. Chem. Res. 2012, 51, 11688–11694. [Google Scholar] [CrossRef]
  23. Ouyang, J.; Tan, Y.; Corr, D.J.; Shah, S.P. Investigation on the mixing stability of asphalt emulsion with cement through viscosity. J. Mater. Civ. Eng. 2016, 28, 04016149. [Google Scholar] [CrossRef]
  24. Taherkhani, H.; Firoozei, F.; Bolouri Bazaz, J. Evaluation of the mechanical properties of the cement treated cold-in-place recycled asphalt mixtures. Int. J. Transp. Eng. 2016, 3, 301–312. [Google Scholar]
  25. Guo, M.; Tan, Y. Interaction between asphalt and mineral fillers and its correlation to mastics’ viscoelasticity. Int. J. Pavement Eng. 2021, 22, 1–10. [Google Scholar] [CrossRef]
  26. Tian, Y.; Lu, D.; Ma, R.; Zhang, J.; Li, W.; Yan, X. Effects of cement contents on the performance of cement asphalt emulsion mixtures with rapidly developed early-age strength. Constr. Build. Mater. 2020, 244, 118365. [Google Scholar] [CrossRef]
  27. Dulaimi, A.; Al Nageim, H.; Ruddock, F.; Seton, L. Microanalysis of Alkali-Activated Binary Blended Cementitious Filler in a Novel Cold Binder Course Mixture. In Proceedings of the The 38th International Conference on Cement Microscopy, Lyon, France, 17–21 April 2016; pp. 189–205. [Google Scholar]
  28. Li, W.; Hong, J.; Zhu, X.; Yang, D.; Bai, Y.; Liu, J.; Miao, C. Retardation mechanism of anionic asphalt emulsion on the hydration of Portland cement. Constr. Build. Mater. 2018, 163, 714–723. [Google Scholar] [CrossRef]
  29. Ayar, P. Effects of additives on the mechanical performance in recycled mixtures with bitumen emulsion: An overview. Constr. Build. Mater. 2018, 178, 551–561. [Google Scholar] [CrossRef]
  30. Castañeda López, M.A.; Fedrigo, W.; Kleinert, T.R.; Matuella, M.F.; Núñez, W.P.; Ceratti, J.A.P. Flexural fatigue evaluation of cement-treated mixtures of reclaimed asphalt pavement and crushed aggregates. Constr. Build. Mater. 2018, 158, 320–325. [Google Scholar] [CrossRef]
  31. Ouyang, J.; Li, H.; Han, B. The rheological properties and mechanisms of cement asphalt emulsion paste with different charge types of emulsion. Constr. Build. Mater. 2017, 147, 566–575. [Google Scholar] [CrossRef]
  32. Dodds, W.; Christodoulou, C.; Goodier, C.; Austin, S.; Dunne, D. Durability performance of sustainable structural concrete: Effect of coarse crushed concrete aggregate on rapid chloride migration and accelerated corrosion. Constr. Build. Mater. 2017, 155, 511–521. [Google Scholar] [CrossRef]
  33. Yan, J.; Leng, Z.; Li, F.; Zhu, H.; Bao, S. Early-age strength and long-term performance of asphalt emulsion cold recycled mixes with various cement contents. Constr. Build. Mater. 2017, 137, 153–159. [Google Scholar] [CrossRef]
  34. Zhu, C.; Zhang, H.; Guo, H.; Wu, C.; Wei, C. Effect of gradations on the final and long-term performance of asphalt emulsion cold recycled mixture. J. Clean. Prod. 2019, 217, 95–104. [Google Scholar] [CrossRef]
  35. Lu, D.; Wang, Y.; Leng, Z.; Zhong, J. Influence of ternary blended cementitious fillers in a cold mix asphalt mixture. J. Clean. Prod. 2021, 318, 128421. [Google Scholar] [CrossRef]
  36. Du, S. Effect of curing conditions on properties of cement asphalt emulsion mixture. Constr. Build. Mater. 2018, 164, 84–93. [Google Scholar] [CrossRef]
  37. Dołżycki, B.; Jaczewski, M.; Szydłowski, C. The long-term properties of mineral-cement-emulsion mixtures. Constr. Build. Mater. 2017, 156, 799–808. [Google Scholar] [CrossRef]
  38. Dulaimi, A.; Nageim, H.A.; Ruddock, F.; Seton, L. Laboratory studies to examine the properties of a novel cold-asphalt concrete binder course mixture containing binary blended cementitious filler. J. Mater. Civ. Eng. 2017, 29, 04017139. [Google Scholar] [CrossRef]
  39. Ling, C.; Bahia, H.U. Development of a volumetric mix design protocol for dense-graded cold mix asphalt. Journal of Transportation Engineering, Part B: Pavements 2018, 144, 04018039. [Google Scholar] [CrossRef]
  40. Zhang, C.; Cao, X.; Xi, W.; Wei, W. Prediction model of compaction process parameters for pavement of cement emulsified asphalt mixture based on effective compaction work. Constr. Build. Mater. 2021, 280, 122403. [Google Scholar] [CrossRef]
  41. PD 6691:2010; Guidance on the Use of BS EN 13108: Bituminous Mixtures–Material Specifications. BSI: London, UK, 2010.
  42. BS EN 933-1; Tests for Geometrical Properties of Aggregates: Part 1. Determination of Particle Size Distribution. Sieving Method. British Standards Institution: London, UK, 2021.
  43. EN 1426:2015; BS EN 1426: Bitumen and Bituminous Binders—Determination of Needle Penetration. European Committee for Standardization: Brussels, Belgium, 2015.
  44. EN 1428:2012; BS EN 1428: Bitumen and Bituminous Binders—Determination of Water Content in Bituminous Emulsions—Azeotropic Distillation Method. European Committee for Standardization: Brussels, Belgium, 2012.
  45. EN 1430:2009; BS EN 1430: Bitumen and Bituminous Binders—Determination of Particle Polarity of Bituminous Emulsions. European Committee for Standardization: Brussels, Belgium, 2009.
  46. EN 1427:2015; BS EN 1427: Bitumen and Bituminous Binders—Determination of the Softening Point—Ring and Ball Method. European Committee for Standardization: Brussels, Belgium, 2015.
  47. EN 13614:2021; BS EN13614: Bitumen and Bituminous Binders—Determination of Adhesivity of Bituminous Emulsions by Water Immersion Test. European Committee for Standardization: Brussels, Belgium, 2021.
  48. Asphalt Institute. Asphalt Cold Mix Manual, Manual Series No. 14(MS-14), 3rd ed.; Asphalt Institute: Lexington, KY, USA, 1989. [Google Scholar]
  49. Habeeb, Z.H.; Al-Hdabi, A. Cold Asphalt Mixtures Characteristics with Cement and Sugar Industry Waste Material as Mineral Filler. IOP Conf. Ser. Mater. Sci. Eng. 2021, 1090, 012137. [Google Scholar] [CrossRef]
  50. BS EN 12697: Part 26; Bituminous Mixtures-Test Methods for Hot Mix Asphalt- Stiffness. British Standards Institution: London, UK, 2012.
  51. Li, R.; Leng, Z.; Wang, Y.; Zou, F. Characterization and correlation analysis of mechanical properties and electrical resistance of asphalt emulsion cold-mix asphalt. Constr. Build. Mater. 2020, 263, 119974. [Google Scholar] [CrossRef]
  52. Jiang, J.; Li, Y.; Zhang, Y.; Bahia, H. Distribution of mortar film thickness and its relationship to mixture cracking resistance. Int. J. Pavement Eng. 2020, 23, 824–833. [Google Scholar] [CrossRef]
  53. BS EN 12697: Part 12; Bituminous Mixtures-Test Methods for Hot Mix Asphalt-Determination of the Water Sensitivity of Bituminous Specimens. British Standard Institution: London, UK, 2008.
  54. Singh, B.; Jain, S. Effect of lime and cement fillers on moisture susceptibility of cold mix asphalt. Road Mater. Pavement Des. 2022, 23, 2433–2449. [Google Scholar] [CrossRef]
  55. Dołżycki, B.; Jaczewski, M.; Szydłowski, C. The influence of binding agents on stiffness of mineral-cement-emulsion mixtures. Procedia Eng. 2017, 172, 239–246. [Google Scholar] [CrossRef]
  56. Ouyang, J.; Yang, W.; Chen, J.; Han, B. Effect of Superplasticizer and Wetting Agent on Pavement Properties of Cold Recycled Mixture with Bitumen Emulsion and Cement. J. Mater. Civ. Eng. 2020, 32, 04020136. [Google Scholar] [CrossRef]
  57. Dong, Q.; Yuan, J.; Chen, X.; Ma, X. Reduction of moisture susceptibility of cold asphalt mixture with Portland cement and bentonite nanoclay additives. J. Clean. Prod. 2018, 176, 320–328. [Google Scholar] [CrossRef]
  58. Yadykova, A.Y.; Strelets, L.A.; Ilyin, S.O. Infrared Spectral Classification of Natural Bitumens for Their Rheological and Thermophysical Characterization. Molecules 2023, 28, 2065. [Google Scholar] [CrossRef] [PubMed]
  59. Zhang, H.; Chen, Z.; Xu, G.; Shi, C. Evaluation of aging behaviors of asphalt binders through different rheological indices. Fuel 2018, 221, 78–88. [Google Scholar] [CrossRef]
  60. Liu, Y.; Qian, Z.; Hu, H. Thermal field characteristic analysis of steel bridge deck during high-temperature asphalt pavement paving. KSCE J. Civ. Eng. 2016, 20, 2811–2821. [Google Scholar] [CrossRef]
  61. Lu, P.; Ma, Y.; Ye, K.; Huang, S. Analysis of high-temperature performance of polymer-modified asphalts through molecular dynamics simulations and experiments. Constr. Build. Mater. 2022, 350, 128903. [Google Scholar] [CrossRef]
  62. Li, P.; Jiang, K.; Li, H. High-temperature stability of asphalt mixture with the influence of styrene butadiene styrene. Procedia-Soc. Behav. Sci. 2012, 43, 842–848. [Google Scholar] [CrossRef]
  63. Zhong, K.; Sun, M.; Zhang, M.; Qin, Y.; Li, Y. Interfacial and mechanical performance of grouted open-graded asphalt concrete with latex modified cement mortar. Constr. Build. Mater. 2020, 234, 117394. [Google Scholar] [CrossRef]
  64. Jiang, X.; Zhu, H.; Yan, Z.; Zhang, F.; Ye, F.; Li, P.; Zhang, X.; Dai, Z.; Bai, Y.; Huang, B. A state-of-art review on development and progress of backfill grouting materials for shield tunneling. Dev. Built Environ. 2023, 16, 100250. [Google Scholar] [CrossRef]
  65. Sadique, M.; Al-Nageim, H. Hydration Kinetics of a Low Carbon Cementitious Material Produced by Physico-Chemical Activation of High Calcium Fly Ash. J. Adv. Concr. Technol. 2012, 10, 254–263. [Google Scholar] [CrossRef]
Civileng 06 00046 g001
Figure 1. Adopted methodology.
Figure 1. Adopted methodology.
Civileng 06 00046 g001
Civileng 06 00046 g002
Figure 2. ITSM results.
Figure 2. ITSM results.
Civileng 06 00046 g002
Civileng 06 00046 g003
Figure 3. Moisture susceptibility results.
Figure 3. Moisture susceptibility results.
Civileng 06 00046 g003
Civileng 06 00046 g004
Figure 4. Temperature susceptibility results.
Figure 4. Temperature susceptibility results.
Civileng 06 00046 g004
Civileng 06 00046 g005aCivileng 06 00046 g005b
Figure 5. Morphology details at 3 days for cement paste mixed with asphalt emulsion.
Figure 5. Morphology details at 3 days for cement paste mixed with asphalt emulsion.
Civileng 06 00046 g005aCivileng 06 00046 g005b
Civileng 06 00046 g006
Figure 6. Morphology details at 28 days for cement paste mixed with asphalt emulsion.
Figure 6. Morphology details at 28 days for cement paste mixed with asphalt emulsion.
Civileng 06 00046 g006
Civileng 06 00046 g007aCivileng 06 00046 g007b
Figure 7. EDX analysis results at 3 days for cement paste mixed with asphalt emulsion.
Figure 7. EDX analysis results at 3 days for cement paste mixed with asphalt emulsion.
Civileng 06 00046 g007aCivileng 06 00046 g007b
Civileng 06 00046 g008
Figure 8. EDX analysis results at 28 days for cement paste mixed with asphalt emulsion.
Figure 8. EDX analysis results at 28 days for cement paste mixed with asphalt emulsion.
Civileng 06 00046 g008
Table 1. Gradation of the 14 mm asphalt concrete surface course.
Table 1. Gradation of the 14 mm asphalt concrete surface course.
Sieve Size (mm)% Passing
(Specification Limits)		% Passing (Midpoint of the Specification Limits)
14100100
1077–8380
6.352–5855
225–3128
114–2620
0.06366
Table 2. Physical properties of the aggregate.
Table 2. Physical properties of the aggregate.
PropertiesValue
Coarse aggregates
Water absorption (%)0.7
Bulk specific gravity (g/cm3)2.60
Apparent specific gravity (g/cm3)2.65
Fine aggregates
Water absorption (%)1.5
Bulk specific gravity (g/cm3)2.53
Apparent specific gravity (g/cm3)2.64
Table 3. Properties of bitumen emulsion.
Table 3. Properties of bitumen emulsion.
PropertiesBitumen EmulsionStandard
TypeCationic
AppearanceBlack to dark brown liquid
Base bitumen Penetration, 0.1 mm50EN 1426 [43]
Viscosity—Efflux time 4 mm at 50 °C, s15–70
Bitumen content, %50EN 1428 [44]
Particle surface electric chargepositiveEN 1430 [45]
Boiling Point, °C100
Softening Point, °C50EN 1427 [46]
Adhesiveness≤90%EN 13614 [47]
Density, g/cm31.016
Table 4. Compositional information for all mixes.
Table 4. Compositional information for all mixes.
Mix IDLimestone, %OPC, %PMWCBitumen Emulsion, %
0% OPC6%0%3%12.5%
1.5% OPC4.5%1.5%3%12.5%
3% OPC3%3%3%12.5%
4.5% OPC1.5%4.5%3%12.5%
6% OPC0%6%3%12.5%
Table 5. Conditions for the ITSM test.
Table 5. Conditions for the ITSM test.
ItemValue
Rise time (ms)124 ± 4
Transient peak horizontal deformation (μm)5
Loading time (s)3–300
Poisson’s ratio0.35
No. of test plus5
No. of conditioning plus10
Test temperature (°C)20 ± 0.5
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

Dulaimi, A.; Kadhim, Y.N.; Quraishy, Q.A.A.; Hawesah, H.A.; Ribeiro, T.P.; Bernardo, L.F.A. Mechanical Properties and Microstructure of High-Performance Cold Mix Asphalt Modified with Portland Cement. CivilEng 2025, 6, 46. https://doi.org/10.3390/civileng6030046

AMA Style

Dulaimi A, Kadhim YN, Quraishy QAA, Hawesah HA, Ribeiro TP, Bernardo LFA. Mechanical Properties and Microstructure of High-Performance Cold Mix Asphalt Modified with Portland Cement. CivilEng. 2025; 6(3):46. https://doi.org/10.3390/civileng6030046

Chicago/Turabian Style

Dulaimi, Anmar, Yasir N. Kadhim, Qassim Ali Al Quraishy, Hayder Al Hawesah, Tiago Pinto Ribeiro, and Luís Filipe Almeida Bernardo. 2025. "Mechanical Properties and Microstructure of High-Performance Cold Mix Asphalt Modified with Portland Cement" CivilEng 6, no. 3: 46. https://doi.org/10.3390/civileng6030046

APA Style

Dulaimi, A., Kadhim, Y. N., Quraishy, Q. A. A., Hawesah, H. A., Ribeiro, T. P., & Bernardo, L. F. A. (2025). Mechanical Properties and Microstructure of High-Performance Cold Mix Asphalt Modified with Portland Cement. CivilEng, 6(3), 46. https://doi.org/10.3390/civileng6030046

Article Metrics

Back to TopTop