Cold Mix Asphalt Research Articles

Self-healing Cold Mix Asphalt Containing Steel Slag: A Sustainable Solution to Cleaner Production

Cold-mix asphalt, produced at ambient temperatures, generates significantly lower CO2 emissions compared to hot-mix asphalt, which requires high-temperature mixing and compaction. However, concerns have arisen regarding the lower durability of cold-mix asphalt when exposed to various environmental stressors, leading to the formation of cracks. This paper explores the benefits of a hybrid application of coarse and powdered slag to enhance crack healing in cold-mix asphalt through the use of microwave radiation. To do so, we quantified extent of microwave-induced healing in dry, wet and freeze-thaw conditioned cold mix asphalt containing steel slags. Latter healing is facilitated by heat generated via absorption of electromagnetic waves. Heat distribution within the specimens and crack zone found to be more uniform when the coarse slag (>4.75mm) was supplemented with slag powder (∼0.075mm) as evidenced by thermography analysis. It was further found that freeze-thaw conditioned specimens significantly benefited from microwave-induced healing as evidenced by a 74% recovery in semi-circular bending strength. This enhancement is attributed to the increased diffusion and contact area at heated crack surfaces. Overall, microwave treatment of cold mix asphalt specimens showed an increase in binder wettability and aggregate coating, resulting in improved performance. Notably, the most significant improvements were observed in the stiffness modulus, with increases of 23%, 46%, and 70% for dry, wet, and freeze-thaw conditioned specimens, respectively. Study outcomes support the vision toward the NetZero carbon emission pavements by promoting the durability of cold-mix asphalt to be a viable alternative to hot-mix asphalt.

Coal-derived electrically conductive asphalt pavements for snow/ice melting: From laboratory to field

Timely removal of ice and snow from roads is critical to safe, fast, and uninterrupted transportation networks in cold regions. Constructing electrically conductive asphalt pavements to melt the ice and snow on the roads through resistive heating is an emerging alternative technology to traditional snow/ice removal approaches such as utilizing snowplow machines and deicing chemicals. Carbon-based fibers and fillers including carbon fiber and graphite have been widely reported to make electrically conductive hot mix asphalt mixtures for pavement snow/ice-melting applications. This study aimed to develop and demonstrate a novel type of electrically conductive asphalt pavements for snow/ice-melting, which utilizes electrically conductive cold mix asphalt (CMA) mixtures incorporating coal-derived carbon-based coke aggregate as resistive heating elements. Both laboratory experiments and field tests were conducted to investigate the electrical, mechanical, and thermal properties of such electrically conductive asphalt mixtures and pavements. The laboratory experiment results indicated that the electrically conductive CMA mixtures incorporating coke aggregate had sufficiently high electrical conductivity and satisfactory mechanical performance and the pavement prototype slab utilizing a thin layer of such CMA mixtures could successfully raise the pavement surface temperatures to 8.3–11.7 °C from a low temperature of −5 °C with an input power density of 473 W/m2. The field test results showed that the full-scale coal-derived electrically conductive asphalt pavements were able to increase the pavement surface temperatures when electricity was applied, but the magnitude of temperature increase was highly dependent on the power density. Therefore, it is promising to use coke aggregate to construct coal-derived electrically conductive asphalt pavements for snow/ice melting.

Steel slag aggregate property improvement in cold mixed asphalt mixtures through surface modification treatment

Expanding the resource utilization of solid waste steel slag (SS) is necessary to reduce the environmental impact of stockpiling and disposal. However, SS has the shortcomings of poor volume stability and poor water damage resistance, which limits its application in pavement engineering, especially in cold mixed asphalt mixtures. In this work, hexamethylene diisocyanate biuret (containing -NCO) and hydroxyl acrylic resin (containing -OH) were utilized as raw materials to prepare NCO-OH composite modifier (NOCM) by regulating NCO/OH (0.75, 1.00, 1.25, and 1.50) for SS surface modification. Surface morphology, adhesion properties, aggregate properties, and prepared mixture properties of SS before and after modification were investigated, respectively, and the curing mechanism of NOCM and action mechanism were analyzed. Results show that the cured NOCM forms a dense modified film on the SS surface, and the rough surface and large pores of SS were blocked, which effectively hindered the free oxides in SS from coming into contact with water. NOCM reduced the apparent relative density, water absorption, and wear loss of SS. NOCM with NCO/OH = 1.25 was recommended to modify SS to obtain the most balanced properties, at which time MSS has a roughest surface to mechanically interlock with asphalt, and there are excess -NCO groups to chemically bond with polar components in asphalt. Mixtures prepared at the optimum NCO/OH had good water damage resistance, freeze-thaw cycle resistance, and volume stability. Applying NOCM-modified SS in environment-friendly cold mixed asphalt mixtures can effectively improve pavement durability and bring good environmental benefits.

Fabrication of High-Performance Asphalt Mixture Using Waterborne Epoxy-Acrylate Resin Modified Emulsified Asphalt (WEREA)

Existing research shows that using waterborne epoxy resin (WER) instead of emulsified asphalt as the binder for cold mix asphalt (CMA) can enhance the rutting resistance, high-temperature performance, fracture performance, and early performance of CMA. In order to eliminate the potential drawbacks such as insufficient strength and low-temperature performance of CMA during application, a novel method was proposed in this study for the preparation of waterborne epoxy-acrylate resin (WER), specifically tailored to modify emulsified asphalt, resulting in waterborne epoxy-acrylate resin emulsified asphalt (WEREA). The modification effect of WER on emulsified asphalt was evaluated through rheological tests and direct tensile tests. A modified design method based on the conventional Marshall design method was proposed to determine the optimal mix proportions, including the key parameters of specimen compaction and curing. The results revealed that the incorporation of WER led to a substantial improvement in the complex shear modulus and a concurrent decrease in the phase angle. When the temperature exceeded 60 °C, the phase angle exhibited a diminishing trend, indicative of a reduced viscosity as temperatures escalated. As the WER content increased, a decrease in the direct tensile strain rate was observed, accompanied by a substantial elevation in direct tensile strength. At various stress levels, the shear strain of WEREA decreases with increased content of WER, indicating that the incorporation of WER can enhance the hardness of emulsified asphalt and improve its deformation resistance. The results from MSCR tests indicate that WER could significantly improve the elasticity and hardness of emulsified asphalt, transitioning it from a viscoelastic material to an elastic material, thereby improving its deformation resistance, resistance to rutting, and high-temperature performance. The results of fatigue life are consistent with those of the amplitude sweep, both reflecting the improvement of resistance to deformation of emulsified asphalt by WER. This indicates that WER has a significant improving effect on the fatigue resistance of emulsified asphalt. Furthermore, the Marshall design tests further confirmed the advantages of WEREA in asphalt mixtures. The optimal preparation for the WEREA mixture was proposed as follows: double-sided compaction for 50 times each, aging at 60 °C for 48 h, optimal moisture content of 5.14%, cement content of 2.5%, and emulsion content of 8.4%. The optimal mix proportions identified through these tests yielded asphalt mixtures with significantly improved stability, reduced flow value, and enhanced rutting resistance compared to the hot-mix asphalt mixture (HMA) of AC-16. These findings suggest that WEREA has the potential to significantly enhance the durability and longevity of asphalt pavements. For future applications, it can be explored for use in producing cold recycled asphalt mixtures. In addition to designing the WEREA mixture according to AC-16 gradation, consideration can also be given to using a gradation with a smaller nominal maximum aggregate size for the application in the surface layer or ultra-thin wearing course.

The effect of anionic emulsifiers’ diversity and manufacturing processes on the stability and mechanical properties of the water-based epoxy-emulsified asphalt

Emulsified asphalt mixtures’ cold mix and paving features facilitate asphalt pavements in fulfilling dual-carbon and energy-saving demands. Anionic emulsifiers can enhance emulsion stability, ensure uniform dispersion of oil and water, possess good decompression viscosity, thickening, and lubricating properties, and maintain good stability under acidic conditions. Nevertheless, anionic emulsified asphalt is restricted in engineering applications due to problems like its storage stability. In this paper, eight anionic emulsifiers and two preparation procedures were chosen for stability tests. Through static tests, storage tests, sieve residue tests, and laser particle size tests, the impacts of emulsifiers on the storage stability and dispersion of asphalt were analyzed. Waterborne epoxy resin exhibits excellent adhesive properties, mechanical properties, chemical resistance, and heat stability. A fluorescence microscope test, static and storage test, laser particle size test, and cementation test were employed to explore the effects of different preparation processes and waterborne epoxy mixing ratios on emulsified asphalt’s storage stability, dispersion stability, and structural stability. The results showed that: (1) the emulsified asphalt prepared with the BWH-02 emulsifier exhibits the best storage stability, and blending with 20% of the waterborne epoxy modifier can notably enhance the bonding properties; (2) the shear strength of the BWH-02 waterborne epoxy emulsified asphalt prepared can reach 1.543 MPa, and the tensile viscosity can reach 0.848 MPa; (3), The emulsified asphalt prepared by the process of modification has better storage stability than that prepared by the side of the emulsification process. Moreover, the storage stability of emulsified asphalt prepared by emulsification and modification is superior to that of the emulsification and modification process. This research provides theoretical and technical support for popularizing and applying cold-mixed cold-paving asphalt mixtures.

Rheological behavior analysis of emulsified cutback composite cold-mixed epoxy asphalt binder based on apparent viscosity

In this paper, a composite cold-mixed epoxy asphalt binder (CCEAB) is made using diluted epoxy resin (DER) and cold-mixed solvent (CMS). The rheological behavior of CCEAB is analyzed by rotary viscosimeter at different temperatures, curing times, shear rates, DER and CMS contents. The fluid type of the CCEAB is identified, and its flow curve is modeled. The parallel phenomenon of apparent viscosity curves is revealed, and the shift factor is analyzed. The results showed that temperature, CMS content and shear rate are negatively correlated with viscosity, while time and DER content are positively correlated with it. CCEAB has typical shear thinning behavior and is a pseudoplastic fluid without yield stress. When the shear rate is greater than 18.6 s−1, the viscosity curves trend stable, and the final viscosity is about 60 % of the initial viscosity. The 5 variables have been added to the power law model to establish the flow curve of CCEAB, whose parameters are identified by the generalized inverse matrix. The parallel of viscosity curves follows the time-temperature superposition, and the shift factor function with 4 variables describes the conversion of viscosity curves. The flow curve of CCEAB has the same form and essence as the shift factor function, meaning the flow curve also describes the parallel. If the shift factor is regarded as a viscosity prediction method, it is not as accurate as the flow curve.

Design and Microwave Absorption Performance Study of SiC-Fe3O4 Emulsified Asphalt Mixture.

To address the challenges of slow curing speed and suboptimal microwave absorption during the paving of cold-mixed and cold-laid asphalt mixtures, this study introduces SiC-Fe3O4 composite material (SF) into emulsified asphalt mixtures to enhance microwave absorption and accelerate curing via microwave heating. Initially, based on the maximum density curve theory, an appropriate mineral aggregate gradation was designed, and the optimal ratio of emulsified asphalt mixture was determined through mixing tests, cohesion tests, wet wheel wear tests, and load wheel sand adhesion tests. Subsequently, the influence of SF content on the mixing performance of emulsified asphalt mixtures was analyzed through mixing and consistency tests. Finally, the microwave absorption performance of the mixture was evaluated by designing microwave heating tests under different conditions, using temperature indicators and quality indicators. The experimental results indicate that when SF content ranges from 0% to 4%, the mixing performance of the emulsified asphalt mixture meets specification requirements. The dosage of SF, SF composite ratio, and microwave power significantly impact microwave absorption performance, whereas environmental temperature has a relatively minor effect. The optimal mix ratio for the emulsified asphalt mixture is mineral aggregate:modified emulsified asphalt:water:cement = 100:12.8:6:1. The ideal SF dosage is 4%, with an optimal SiC to Fe3O4 composite ratio of 1:1, and a suitable microwave power range of 600-1000 W.

Application of solid waste materials in cold bitumen emulsion mixtures for cleaner pavement industry: a comprehensive review.

There is a global concern with continuous waste production, and efforts are underway to use these wastes in the construction sector. The negative effects of excessive waste production and the use of virgin materials and energy in Hot Mix Asphalt (HMA) construction are challenging and require attention. The right step towards developing resilient road infrastructure is using cold bitumen emulsion mixtures (CBEMs), a cold mix asphalt (CMA). A long-term fix to issues with waste generation and the creation of flexible pavements with HMA can be found by incorporating wastes into CMA. This work reviews the utilization of numerous wastes from different sectors (agricultural, industrial, construction and demolition, and municipal) that are well-known but underutilized and could be used as potential fillers in cold asphalt mixtures. Focus is given to the critical analysis of wastes' physiochemical characteristics and how these affected the effectiveness of mixtures against primary distresses like stability, stiffness, rutting, cracking, fatigue, and moisture susceptibility. Almost all waste materials incorporation reported enhancement in the mechanical performance of CBEM mixes concerning conventional CBEM mixes. The paper sums up the impact on various mechanical properties of CBEM mixes utilizing waste material filler, presents research gaps and a way forward to inspire researchers, and serves as a guideline for using waste materials as fillers in CBEM mixes. This will improve environmental quality and promote sustainability in the paving industry.

Property improvement of epoxy emulsified asphalt modified by waterborne polyurethane in consideration of environmental benefits

Waterborne epoxy modified emulsified asphalt (EMEA) has the shortcomings of insufficient toughness and poor aging resistance, which limits its application of low-carbon cold-paving technology in plateau zones. To obtain a cold-mix asphalt binder with excellent performance, waterborne polyurethane (WPU) was utilized to modify EMEA in this work. Properties, modification mechanism, action process, environmental benefits, and cost-benefit of composite-modified emulsified asphalt (CMEA) were analyzed. Results show that CMEA had good rutting resistance, low-temperature rheological, tensile toughness, adhesion with aggregate and moisture damage resistance, and aging resistance properties. These were closely related in that WPU was cross-linked with the waterborne epoxy resin (WER) to form an interpenetrating polymer network (IPN) structure, when the space network structure of WER and the soft and hard segments of WPU worked together. Based on the above results, it was recommended that EA containing 4.0 wt% WER was modified by 7.5 wt% WPU to achieve the best pavement properties. Furthermore, it was discovered that a physical process by which WER and WPU modified EA, served as a skeleton connection and toughening agent. CMEA has excellent performance and is especially suitable for use in low-temperature and strong aging areas, while can bring good environmental benefits.

Study on the micromorphologies and structural evolution in cold-mixed epoxy asphalt

Cold-mixed epoxy asphalt (CMEA) is a high performance paving material that can be constructed and cured at room temperature. It forms thermal and mechanical performances during curing process. In this study, the phase state and structural evolution characteristics of CMEA during curing were evaluated by curing rheological behavior, mechanical properties, and micromorphology. Viscosity tests and dynamic mechanical analyses (DMA) were applied to study the curing rheological behavior, and tensile tests were used to determine the mechanical properties. Moreover, fluorescence microscopy (FM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were implemented to investigate the micromorphological and molecular structure evolution. The results showed that the curing reaction behavior of CMEA was closely related to temperature. The viscosity–time curves of CMEA satisfied the Arrhenius equation above 45 ℃ and followed a linear trend at low temperature. During the curing of CMEA, the toughness increased in three stages: the toughness growth stage, toughness stability stage and toughness decay stage. Furthermore, the presence of asphalt and its solvent weakened the curing reaction of epoxy asphalt. However, increasing the reaction temperature could increase the epoxy group conversion rate. When the curing reaction was complete, a considerable amount of asphalt solvent mixed with the asphalt and was uniformly distributed within the three-dimensional network structure of the epoxy resin. This mixture adversely affected the toughness of the cured CMEA.

Evaluation of the electrochemical interaction in the asphalt emulsion-aggregate system of cold mix asphalt through zeta potential and surface free energy analysis

ABSTRACT The interaction in the emulsion-aggregate system is well known and influences the Cold Mix Asphalt (CMA) performance. However, the electrochemical interaction indexes for the emulsion-aggregate systems are still not well understood. Therefore, the present investigation focussed on evaluating the electrochemical interaction in the Asphalt Emulsion-Aggregate system (AEA-S) of Cold Mix Asphalt (CMA). Zeta Potential (ZP), X-ray diffraction (XRD), and Surface Free Energy (SFE) analysis were carried out in three slow-setting cationic asphalt emulsions and three common Colombian aggregates (alluvial and quarried) to determine the electrical potential and interaction in the emulsion-aggregate system. Zeta Potential analysis shows both dependence on the chemical compounds of the aggregates and variation in pH conditions. Moreover, Zeta Potential shows negative values for all three aggregates in the entire pH range variation and decreases with asphalt emulsions pH associated with SiO 2 / Al 2 O 3 ratio. Through chemical identification and electrokinetic forces is feasible to conclude that high Zeta Potential (ZP) and Surface Free Energy (SFE) values improve the electrochemical ad of the asphalt emulsion-aggregate system (AEA-S), demonstrating that high polarity is an essential factor in Cold Mix Asphalts (CMA).

Effect of Binary Blended Fillers on the Durability Performance of Recycled Cold-Mix Asphalt

Cold-mix asphalt is a greener alternative to pavement construction, processed at 10–40 °C, which is typically lower than other techniques like warm-mix asphalt and hot-mix asphalt. Huge amounts of construction and demolition waste, such as broken bricks, recycled concrete aggregates, reclaimed asphalt pavement, ceramic waste, etc., are generated every year due to the acceleration in infrastructure development. The production of such massive amounts causes landfilling issues, and their disposal is a serious issue nowadays. This study examines the effect of binary blended fillers on the performance of cold asphalt mixes using emulsified binders and 50% reclaimed asphalt pavement materials. Moreover, three types of binary blended fillers (BBFs), cement, fly ash, and Stabil Road, were used at different dosages. Overall, 500 samples were prepared for the mix design, and the optimum emulsion content was determined as 11% and 9% for the CM and 50R mixes, respectively, based on the Marshall stability peak value and volumetric properties such as voids in the mineral aggregates, total voids, and dry density. The moisture susceptibility of the recycled cold-mix asphalt (RCMA) mixture was evaluated using the tensile strength ratio. Cantabro abrasion loss was used to assess the cohesion resistance of the mixtures. The dynamic response of the mixes to the applied load was evaluated using the resilient modulus. The results of the present study reveal that using BBFs in the RCMA improved the inter-particle bonding and strength. Furthermore, BBF incorporation enhanced the performance of the recycled cold-mix asphalt.

Epoxy-ended hyperbranched polymer-grafted graphene oxide for cold-mixed epoxy asphalt modification

ABSTRACT To improve the compatibility of asphalt-epoxy and mechanical properties of cold-mixed epoxy asphalt (CEA), epoxy-ended hyperbranched polymer (EHBP) was grafted on the surface of graphene oxide (GO) nanoplates to synthesize GOEHBP as a compatilizer. The chemical structures and micromorphology of GOEHBP were analysed through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermo gravimetric analysis and transmission electron microscopy. The CEA modified by EHBP and GOEHBP was investigated by tensile test, dynamic thermomechanical analysis, viscosity test, fluorescence microscope experiment, FTIR analysis and XPS analysis. The results showed that the EHBP was successfully grafted onto the surface of GO via chemical reaction, and the GO was partially reduced. The mechanical properties of CEA modified by EHBP are obviously improved, and the elongation at break was increased by 74.5%. The glass transition temperature of CEA modified by GOEHBP was increased to 62.58°C. At high temperature (≥40°C), the E′ of CEA modified by GOEHBP was larger than that of the CEA, indicating that GOEHBP can improve the high-temperature deformation resistance of CEA. The addition of GOEHBP can improve the compatibility of asphalt-epoxy, thus improving the toughness of CEA.

Mechanical performance of cold mix asphalt containing cup lump rubber as a sustainable bio-modifier

The road construction industry aims to contribute to the protection of already compromised environment. Cold mix asphalt (CMA) is a measure initiated by the road industry to protect the environment and preserve energy. Despite having additional benefits, CMA has attracted little attention due to its inferior performance. CMA's performance is enhanced using a sustainable binder bio-modifier, natural cup lump rubber (CLR) is one of them. This study evaluated the tensile properties, rutting, moisture susceptibility, and adhesion properties of CLR-modified CMA (CMA-CR). The tensile property was enhanced by 26% due to CLR modification. CMA-CR had excellent rutting resistance of less than 2 mm rut depth at 10,000 load cycles, showing 70% improvement compared with conventional CMA. Moisture susceptibility evaluation indicated that CMA-CR had tensile strength ratio (TSR) value of 104%, satisfying the minimum 80% requirement of AASHTO T283. It also retained more than 96% bitumen coating. The moisture damage resistance was improved by 12% and 10% in terms of TSR and stripping, respectively. The durability results revealed that the CMA-CR mixture prevented higher mass loss, representing 14% improvement compared with conventional CMA.

Eco-efficient asphalt recycling for urban slow mobility

Cycling infrastructures contribute to advancing zero-impact transport systems, aligning with the European Commission’s proactive climate change mitigation policies. This paper explores the potential of innovative and sustainable pavements for cycling paths with mixtures composed of road-milling materials. This investigation involves low-environmental-impact bituminous-based mixtures differing from recipe, mixing method, and laying. Up to 100% secondary aggregates are used as alternative materials to design the Grande Raccordo Anulare delle Biciclette (GRAB), a 44-km cycling ring in Rome. According to the European standard EN 15804, their “from cradle to gate” life cycle analysis allows a comprehensive assessment and comparison of the environmental impact. Core and additional environmental impact categories and resource use indicators were quantified using primary data from asphalt producers and secondary data from the Ecoinvent database in the SimaPro software. Within the H2020 InfraROB project (grant agreement no. 955337), which aims at enhancing road infrastructure integrity, performance, and safety through autonomous robotic solutions and modularization, experimental sections have been constructed using a cold-mixed asphalt composed entirely of recycled asphalt and a rejuvenating additive. The results underscore the potential of the examined low-impact approach in conserving Earth’s resources, ensuring long-lasting infrastructure for vulnerable urban populations and fostering sustainable environmental management.

Comparative analysis of cold-mixed epoxy asphalt models for molecular dynamics simulation: structural, curing and mechanical properties

Comparative analysis of cold-mixed epoxy asphalt models for molecular dynamics simulation: structural, curing and mechanical properties

Optimization of Alkali Activator on the Strength Properties of Fly Ash Based Geopolymer Repair Materials

Flexible and rigid road pavement deteriorates over time and needs high-performance patching repair materials. Cold mix asphalt patching is an easy and inexpensive repair material to repair potholes and other damaged roads. However, the repaired road pavement fails because it doesn’t have adequate compressive and bonding strength to the substrate. Thus, this research uses high-performance geopolymer repair materials to patch against road pavement potholes substrate. Geopolymer repair materials could improve the bonding strength, making them suitable for road repair purposes. For making geopolymer repair materials, the main materials used were high calcium aluminosilicate source materials such as fly ash, sodium hydroxide, sodium silicate, and water. This study tested the compressive and bonding strength of geopolymer repair materials after 1, 7, 14, and 28 days. This study found that the compressive strength of 90 g of alkali activator was the highest, at 37.0 MPa. The bonding strength improved gradually from day 1 to day 14, and then considerably on day 28. The compressive strength and bonding strength both increase in direct proportion to the amount of alkali activator present. Alkali activator is optimal at 90 grams for compressive strength and bonding strength of geopolymer repair materials.

Investigation on the influence of gradation design on the road performance of cold mixed epoxy asphalt mixture based on microstructure evaluation

Cold mixed epoxy asphalt mixture (CMEAM) has excellent anti-deformation and fatigue performance which shows remarkable superiority on bridge pavements. Previous studies have done comprehensive researches on its properties through macroscopic experiments. However, few studies revealed the impact of gradation design on the road property of CMEAM through microscopic method. Thus, in this paper, X-Ray computed tomography (X-ray CT), nanoindentation (NI), field emission scanning electron microscopy (FESEM) and mercury intrusion porosimetry (MIP) are introduced to investigate the coarse aggregates contact degree, the thickness and elastic modulus of interfacial transition zone (ITZ) and the pore diameter distribution of CMEAM. Results showed that the contact points of coarse aggregates in EA-05 mixture are around 40 while those in EA-10 mixture are around 20. (40°, 50°) is the key inclination angle interval for EA-10 mixture type while (70°, 80°) and (10°, 20°) are of significance for EA-05 mixture type. The contact points and inclination angles are positively and inversely proportional to Marshall stability, respectively. In addition, the ITZ thickness of EA-05 and EA-10 mixture is below 10 μm and above 40 μm, respectively. The ITZ elastic modulus of EA-10 mixture is approximately 1.5 times than that of EA-05. The thickness and elastic modulus of ITZ are inversely proportional to low-temperature indirect tensile strain (εT). Meanwhile, EA-05 mixture has higher proportion in gel micropores and middle capillary pores while EA-10 mixture has higher proportion in mesopores and large capillary pores. Mesopores has the highest correlation coefficients with tensile strength ratio (TSR), followed by large capillary pores. The suggested proportion for above two type pores is around 21.5% and 51.0%, respectively.

Performance of Cold-Mix Asphalt with Calcined Eggshell Powder–Activated GGBFS Filler

Performance of Cold-Mix Asphalt with Calcined Eggshell Powder–Activated GGBFS Filler

Waste Cooking Oil as Eco-Friendly Rejuvenator for Reclaimed Asphalt Pavement.

Over 50 MioT of Waste Cooking Oil (WCO) was collected worldwide in 2020 from domestic and industrial activities, constituting a potential hazard for both water and land environments, and requiring appropriate disposal management strategies. In line with the principles of circular economy and eco-design, in this paper an innovative methodology for the valorisation of WCO as a rejuvenating agent for bitumen 50/70 coming from Reclaimed Asphalt Pavement (RAP) is reported. In particular, WCO or hydrolysed WCO (HWCO) was modified by transesterification or amidation reactions to achieve various WCO esters and amides. All samples were characterised by nuclear magnetic resonance, melting, and boiling point. Since rejuvenating agents for RAP Cold Mix Asphalt require a melting point ≤0 °C, only WCO esters could further be tested. Efficiency of WCO esters was assessed by means of the Asphaltenes Dispersant Test and the Heithaus Parameter. In particular, bitumen blends containing 25 wt% of WCO modified with 2-phenylethyl alcohol, showed high dispersing capacity in n-heptane even after a week, compared to bitumen alone (1 h). Additionally, the Heithaus Parameter of this bitumen blend was almost three times higher than bitumen alone, further demonstrating beneficial effects deriving from the use of WCO esters as rejuvenating agents.