Cold Mix Research Articles

Design and evaluation of semi self-compacting cold mix polyurethane mixture for steel bridge deck pavement

To enhance the environmental sustainability and pavement performance of steel bridge deck paving, a novel semi self-compacting cold mix polyurethane mixture (CMPU-10) for steel bridge deck paving was specifically designed and evaluated. Herein, this study presents the first comprehensive documentation of the research process involved in the mix design of CMPU-10. Initially, based on the theory of maximum density curve, a gradation with a Talbot index (n) of 0.40 was identified as the preliminary gradation for designing CMPU-10 by void ratio, compressive strength and slump tests. Subsequently, the aggregate grade-by-grade filling test revealed the critical influence of sieve sizes (0.075 mm, 0.6 mm, and 2.36 mm) on the mixture dense degree. From these findings, an in-depth analysis of the effects of aggregate passage under the key sieve on the degree of mixture density, compressive strengths, and flow properties led to the determination of the gradation range of CMPU-10. The optimum binder-aggregate ratio for the median gradation was determined to be 9.2%. Finally, wheel tracking, semi-circular bending (SCB) and freeze-thaw splitting tests showed that the designed CMPU-10 exhibits superior high-temperature stability performance, low-temperature cracking resistance and moisture susceptibility compared to the TAF epoxy asphalt mixture (EA-10). This paper not only provides a new potential low-carbon material for steel bridge deck paving projects, but also establishes a theoretical foundation for the optimization design and promotion polyurethane mixture.

WASTEWATER SLUDGE ASH IN THE PRODUCTION OF A NOVEL COLD MIX ASPHALT (CMA): DURABILITY, AGING AND TOXICITY CHARACTERISTICS

New Sustainable with no CO2 emission cold mix asphalt (CMA) for road and highways surfacing is successfully developed from wastewater sludge ash normally sent to landfills. The Paper reports; durability in terms of water sensitivity, aging and contamination levels of heavy metals of the new developed novel CMA containing upgraded fly and bottom ash secondary cementitious materials from United Utilities fly and bottom ashes. Road engineers currently restricted the use of conventional CMA containing conventional limestone fillers (LF) for use in walkways and light trafficked roads only, as these mixtures needs from 2 to 24 months for curing. Conventional CMA mixtures also have high voidage contents and thus low traffic bearing capacity. The durability of these mixes is low especially in the UK and European countries where the climate is predominantly wet and cold.In Germany and France, ordinary Portland cement (OPC) replaced the filler used in traditional CMA. Although this allows the new CMA to be used in roads for light and heavy trafficked loads. The materials are not environmentally friendly, as one tone of cement releases approximately one tone of CO2 emission during their manufacturing process. The results of the new developed CMA are satisfying the British and European codes of practices requirements. The new novel mixtures are also; highly cost-effective compared with the use of Hot Mix Asphalt (HMA), has no CO2 emission during mixing construction, and has no health and safety issues compared with the HMA manufacturing and application process.

Investigation of cracking resistance of cold asphalt mixture designed for ultra-thin asphalt layer

Ultra-thin asphalt layers are mostly constructed at high producing temperatures of 165–180 ℃, which results in high energy consumption and extra aging of asphalt binders. Those influences could be eliminated by employing the cold-mix process. However, the reduced cracking resistance of cold asphalt mixtures should be addressed. The objective of this study is to design a preferable cold mix asphalt mixture which can be used for ultra-thin asphalt layer. A cold mix ultra-thin asphalt layer (GT-10 C) with comparable anti-cracking performance was developed through the use of high-performance binder, basalt fibers, and specially designed aggregate gradation. Several cracking resistance tests were employed including the low-temperature bending test, impact toughness test, and semi-circular bending test. In addition, a specified test method was developed for determining cracking resistance and durability of the ultra-thin asphalt layers by using compounded slabs. The testing results were compared with the performance of a conventional hot mix ultra-thin asphalt layer (Hot-UA) and a common micro-surfacing layer with cold mix (Cold-UA). It was found that GT-10 C had larger ultimate tensile strain, impact and fracture toughness than Hot-UA and Cold-UA, and a better fracture life in the thin layer cracking resistance test as well. This research provides a potential technology for producing cold mix ultra-thin asphalt layers.

Optimised mix design for cold mix asphalt considering various curing parameters of loose mixture

Several research works have been carried out to improve cold mix asphalt (CMA), being an eco-friendly construction; however, very few attempts have been made on curing of loose CMA mixture before the compaction process for preparing the specimens that simulate the actual field condition. The present study aims to assess the effect of various curing parameters (curing temperature, curing duration and curing condition) on loose CMA mixture for improvement in the curing rate and strength of compacted samples. The curing rate of the loose mixture was satisfactory in the temperature range of 40–60°C; however, curing in the oven at 50°C closely simulated the local field condition in normal weather. After investigating different processes for effective curing of the loose mix, the protocol with initial 1% moisture loss in the air at room temperature, followed by 3% moisture loss in the oven at 50°C resulted in the optimum CMA properties.

Mechanical properties of cold mixed asphalt

The mechanical and performance characteristics of cold mix asphalt derived from straight-run bitumen blended with dissolved polythene were assessed to determine the engineering, environmental, and economic feasibility of a recently developed product for pavement maintenance. The cold mix asphalt binder was created by treating a portion of straight-run bitumen with chemically dissolved polythene waste sachets at a temperature of approximately 80°C, employing an alkaline emulsifier, chemical surfactant, and water. The formulation for the cold mix asphalt involved 35% coarse aggregates, 65% fine aggregate, and 10% mineral filler, with an optimal binder content of 8.3%. Standard laboratory Marshall tests, static loading/unloading in both laboratory and field settings, and real-time traffic loads were applied to the cold asphalt mixes to establish comparative performance. The Marshall Stability, flow, and density of the experimental cold mix asphalt were determined as 5.08 kN, 4.0 mm, and 1.98 g/cm3, respectively. In comparison, the corresponding values for the other three commercially available cold asphalt mixes ranged from 0 to 4.27 kN, 0 to 5.5 mm, and 1.60 to 1.85 g/cm3. The rate of deformation of experimental cold mix with respect to time and traffic load respectively 0.0086mm/week and 0.00877mm/standard 80 kN standard axle, which are more favorable than the corresponding values for the commercial mixes.

Effect of triangular ribs on the flow and heat transfer characteristics of heat exchanger tube

To improve the heat exchange tube?s comprehensive performance and achieve enhanced heat transfer with lower flow resistance. The flow and heat transfer characteristics of a newly enhanced tube with triangular ribs were studied by numerical simulation. The results show that the multi-vortex longitudinal swirl developed in the triangular rib enhanced tube can enhance the cold and hot fluid mixing, and make the temperature distribution in the tube more uniform. The field synergy of velocity and temperature gradient was improved and the heat transfer capacity was enhanced. In the triangular rib enhanced tube, reducing the dimensionless pitch ratio of triangular ribs (P* = 0.5, 0.75, 1, and 1.25) and appropriately increasing the area of triangular ribs (A = 8, 12, 16, and 20 mm2) can improve the performance evaluation criteria (PEC). When Re = 8475, P* = 0.5, and A = 20 mm2, the maximum PEC = 1.324 is obtained.

Pyrolysis characteristics analysis of cold mix asphalt mixture based on TG-FTIR-GC/MS

This study aims at the pyrolytic behavior of cold mix asphalt mixture (CMAM), and addressing the existing knowledge gap related to their thermal stability in fire-risk scenarios. Based on a combined TG-FTIR-GC/MS approach, the pyrolysis behavior of CMAM was analyzed at heating rates of 10, 20, and 30 K·min−1. Pyrolysis kinetic parameters were calculated and the reaction mechanism function was determined employing both linear and nonlinear methods. The results show that the main phase of pyrolysis weight loss in CMAM occurs within the temperature range of 600–860 ℃, implying weight loss ranging from 41.4% to 41.7%. Activation energy values, determined by the Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) methods, exhibited substantial similarity. Furthermore, the Vyazovkin method was used to confirm the activation energy value. The main peak activation energy, calculated through the Kissinger method, was 172.4473 kJ·mol−1. Moreover, the Coats Redfern (CR) method was used to determine the pyrolysis mechanism model of CMAM as R3. Analysis via infrared spectroscopy indicated that the main small molecule product is CO2. Experimental data from gas mass spectrometry suggested the potential generation of 9 products. This study provided significant reference for a deeper comprehension of the thermal stability and fire safety characteristic of CMAM.

Effect of Mechanical Properties on Performance of Cold Mix Asphalt with Recycled Aggregates Incorporating Filler Additives

The utilization of recycled asphalt pavement in the construction and maintenance of flexible pavement with asphalt emulsion is advantageous and environmentally friendly. It saves energy due to zero heat loss during the mixing and laying of pavement compared to hot mix asphalt. Recycled asphalt pavement (RAP) is a sustainable material in place of virgin aggregates in road construction. The focus of this study is (i) virgin aggregate production, (ii) the utilization of waste material (additive), (iii) reducing the production temperature, and (iv) recycled RAP material in the pavement. This paper attempts to create a venue for using RAP greater than 50% during pavement construction. Cold mix asphalt (CMA) containing 0%, 50%, and 100% RAP materials with different dosages of cement, fly ash, and Stabil-road at 1%, 2%, and 3% of dry aggregate weight were used for ascertaining the mechanical and volumetric properties of mixtures. The mechanical properties for CMA samples, such as stability, tensile strength, moisture susceptibility, stiffness modulus, and the abrasion loss of CMA samples, were evaluated with and without RAP incorporation. Present laboratory studies revealed that a cold mix containing 50% RAP materials produced a higher stability value than the control mix, irrespective of the types of additives in its contents. All the additives can potentially resist moisture damage in the mix. Also, a significant improvement in the resilient modulus was considered for RAP-incorporated mixtures with the additives.

Mitigation approach of plastic and microplastic pollution through recycling of fishing nets at the end of life

Plastic and microplastic pollution in the marine environment is a global issue and lost or discarded fishing nets (FNs) represent a relevant part of the marine litter. This type of waste is very harmful to marine organisms due to ghost fishing and microplastics release. Furthermore, nets are difficult to dispose because they take up a lot of space at landfill sites and are expensive to transport. Therefore, the development of recovery and recycling strategies represents one of the solutions for this problem. In the present work, a multifilament, knotted, twisted waste FN, composed of nylon 6,6, was recycled realizing composite materials in combination with recycled expanded polystyrene (EPS) or poly(acrylonitrile-butadiene-styrene) (ABS) matrices. The composites were realized exploiting a cold mixing approach, mixing the FN, either as a pre-ground short fiber filler or as mats, with the polymers swollen in an organic solvent. Several compositions were explored by these approaches and the composites were characterized by means of thermal, spectroscopic, mechanical and morphological analyses. Finally, a qualitative assessment of the economic impact of fishing net recycling was conducted. Results showed that the proposed recycling approaches allow to realize composite materials with interesting properties, opening new routes for recycling the FNs at the end of life improving the circular economy of plastics and reducing their ecological, ecosystem service and social and economic impacts.

Investigation on strength characteristics and mechanism of cold mix based on geopolymerization reaction

Cold mix asphalt is an energy-efficient and eco-friendly pavement material, yet its early strength is deficient. This study investigated the strength augment of cold mix asphalt through modification with geopolymer additives. Macro-strength was assessed via Marshall stability testing under varied geopolymer contents, curing durations, and water immersion conditions. Microscale analysis encompassed fluorescence microscopy to discern geopolymer-asphalt interactions and discrete element modeling to simulate the compression process. Results showed that stability rose and then fell as geopolymer content increased, with an optimal ratio of 4:3 between base asphalt and additive. Stability increased rapidly in the first 3 days of curing and accumulated at a slower rate afterwards. Fluorescence microscopy revealed that geopolymer bonded the asphalt to the aggregate surfaces. Modeling exhibited geopolymer resisted vertical loads and confined the aggregate. In summation, geopolymerization enhances cold mix strength by improving adhesion and generating a rigid 3D network encompassing aggregate particles. The discoveries provide guidance on formulating durable cold mix asphalt utilizing geopolymer additives.

Laboratory Investigation and Machine Learning Modeling of Road Pavement Asphalt Mixtures Prepared with Construction and Demolition Waste and RAP

Due to the decreasing availability of virgin materials coupled with an increased awareness of environmental sustainability issues, many researchers have focused their efforts on investigating innovative technological solutions in the civil engineering domain. This paper aims to evaluate the suitability of construction and demolition waste (C and DW) and reclaimed asphalt pavement (RAP) reused within asphalt mixtures (AMs) prepared for the binder layer of road pavements. Both hot and cold mixing methodologies were investigated. The technical assessment was based on the volumetric and mechanical suitability, according to saturated surface dry voids (SSDV) and indirect tensile strength (ITS) tests carried out at 10 °C, respectively. Laboratory findings showed that all the hot AMs matched the desired target SSDV at the design gyrations number at different optimum bitumen content levels, alternatively showing a non-significant variation or a significant increase in ITS compared to conventional hot mix asphalt. Conversely, the cold AMs with cement and emulsion bitumen showed a greater volume of voids and moisture sensitivity, and lower temperature susceptibility compared to hot AMs, reaching, on average, 11% lower ITS when using coarse C and DW aggregates and 43% lower ITS when using filler from C and DW. These volumetric and mechanical properties were modeled by means of support vector machines and categorical boosting (CatBoost) machine learning algorithms. The results proved to be satisfactory, with CatBoost determination coefficients R2 referring to SSDV and ITS equal to 0.8678 and 0.9916, respectively. This allowed for the mechanical performance of these sustainable mixtures to be predicted with high accuracy and implemented within conventional mix design procedures.

Fracture toughness of colored slurry seal at low temperatures and different loading Modes: Comparative study with warm and hot mix asphalt materials

Sustainable pavement, including colored slurry seal, was treated by crack growth under different traffic loads and temperatures. The current research examined colored slurry seals’ fracture toughness at various temperatures under mixed modes I/II and I/III. Three-point bend fixtures were used to prepare edge-notched disk bend (ENDB) disk specimens with edge cracks along one side of the specimens. Then, different temperatures and complete range mode mixity, including I/II and I/III, were used to determine fracture toughness data as well as the critical stress-intensity factor. Results indicated that the samples’ fracture resistance initially declined followed by an increment by an increment in the shear load in I/II mixed mode. From pure mode I to III, colored mixture resistances decreased with crack growth by raising mode III fraction at the crack tip. Moreover, lower temperatures led to better fracture performance between mixtures, especially at −20 °C. Mixtures’ fracture performance was positively influenced by temperature reduction due to bitumen strength characteristics. Comparison of fracture envelopes of cold mix asphalts (CMAs) in I/II and I/III mode mixities with other types of asphalt concrete, such as warm and hot mix asphalt (WMA and HMA), showed higher susceptibility of CMA mixture to cracking failure mode, making it noticeably weaker than WMA and HMA mixtures.

Investigating the Impact of Polymer and Portland Cement on the Crack Resistance of Half-Warm Bituminous Emulsion Mixtures

Cold mix asphalt (CMA) is emerging as an environmentally friendly alternative to traditional hot mix asphalt (HMA). It offers advantages such as lower costs, reduced energy demands, decreased environmental impacts, and improved safety aspects. Among the various types of CMA, the cold bitumen emulsion mixture (CBEM) stands out. The CBEM involves diluting bitumen through emulsification, resulting in lower bitumen viscosity. However, this process has certain drawbacks, including extended setting (curing) times, lower early strength, increased porosity, and susceptibility to moisture. This study focuses on enhancing CBEM properties through the utilization of low-energy heat techniques, such as microwave technology, and the incorporation of a polymeric additive, specifically acrylic. These innovations led to the development of a novel paving technology known as a half-warm bitumen emulsion mixture (HWBEM). The research was conducted in two phases. First, the study assessed the impact of low-energy heating on the CBEM. Subsequently, it explored the combined effects of low-energy heating and the addition of an acrylic polymer. CBEM samples containing ordinary Portland cement (OPC) as an active filler were utilized in the sample manufacturing process. The effectiveness of these techniques in enhancing crack resistance was evaluated by analysing the results of the indirect tensile strength test. Notably, CBEM samples containing an amount of 2.5% of acrylic polymer and OPC exhibited the highest resistance to cracking. Furthermore, significant improvements were observed in their volumetric and mechanical properties, comparable to those of HMA.

Performance-related methods for the characterization of cold mix patching materials used in asphalt pavements maintenance

Cold mix patching materials (CMPMs) are commonly used as an alternative to hot mix asphalt (HMA) for repairing road pavement potholes, especially in cold and wet seasons. Currently, the acceptance criteria and expectations for the mechanical strength and durability of CMPMs are often compared or related to those adopted for traditional HMA pavements without considering the specific performance characteristics of CMPMs required to ensure their effectiveness. In response to this, the authors proposed innovative solutions derived from pre-existing methodologies to evaluate CMPMs. Several parameters, indicative of CMPMs' structural and functional performance, were measured to optimize the mix design and systematize the quality assurance/quality control (QA/QC) process at various service life stages and under different boundary conditions. Besides the standard Marshall stability and indirect tensile strength (ITS), which were chosen as references, Hubbard-Field and indentation stability tests were reintroduced, suggesting modified procedures specifically tailored to CMPM stability evaluation. Similarly, brush, Leutner, and locking point test methods were customized for analyzing the raveling potential, bonding properties, and workability of the patching materials. The research outcome showed that Hubbard-Field and indentation stability tests provided more accurate stability assessments, even for materials unsuitable for testing using Marshall stability and ITS methods. Modified brush and Leutner tests effectively replicated real-world conditions, enhancing the relevance of laboratory findings to practical applications. Furthermore, the locking point method enabled mixture workability classification. These findings contribute to a better understanding of CMPM performance and can inform more targeted and effective road repair strategies.

Characterization of Oil and Diesel Waste Modifiers in Lasbutag Asphalt Cold Mix (Aggregated Buton Asphalt Layer)

One of the uses of Buton Asphalt is LASBUTAG which is a road surface with a mixture of Asbuton, modifier and aggregate. Currently, heavy oil as a modifier is scarce in the market, so it is necessary to consider other alternatives as a modifier, one of which can be used, namely waste oil motor vehicle or other machinery. The aim of this study is to analyze the ideal modifier variation in Lasbutag blends using Lombah oil and diesel fuel as modifiers. This research is a quantitative research using experimental methods conducted in the laboratory. The use of the modifier with waste oil and diesel fuel for Lasbutag cold mix pavements can meet the Marshall characteristics required in the special Lasbutag specifications. The stability required in the Lasbutag special specifications is met by using a modifier content of 4.2% to 6.8%, VIM can be achieved at different modifier levels between 4.8% and 7.2%, Cavity Parameters Between Mineral Aggregates (VMA) can be achieved using modifiers from 4% to 7.0% and Melt Value (Flux) can be achieved using modifiers from 4% to 6 .2%. The cold-mixed Lasbutag characteristics required in the Lasbutag special specifications can be met using a modifier between 4.8% and 6.2%, so the most ideal modifier is achieved at 5.5%.

The Potential Usage of Bitumen Cold Mix and Tire Chips as Stabilization Material on Clay Soil Strength Characteristics

Clay is a soil with fine particle size less than 0.002 mm, low permeability, cohession, high swelling, and slow consolidation process. Due to that problem it needs some improvement to stabilize the condition of soil before the process of construction conducted. The purpose of this study is to determine the effect of adding shredded tire and cold mix bitumen as the value of shear strength changing are cohession, friction angle, and shear strength with triaxial unconsolidated undrained test. To see the effect of those mixture, this study uses 48 soil samples with 4 variation of shredded tired (0%, 1%, 1,5%, and 2%) and 4 variation of cold mix bitumen (0%, 1%, 2%, dan 3%). The result of this study showed that the adding of shredded tired and cold mix bitumen in soil compositition can increase parameters of soil. The optimum cohession is on variation 1% SB+2% B (T99B2SB1) with the value 0.61 kg/cm2. Meanwhile the optimum value of friction angle is on variation 1.5% SB+ 1% B (T98.5B1SB1.5) with the value 7.43o. The shear strength as the sum of cohession and friction angle tends to increase with the optimum value about 0.995 kg/cm2 in variation 2% bitumen and 1% shredded tire (T99B1SB1). From the study, the adding of shredded tired and cold mix bitumen improve the shear strength. The optimum value of shear strength is on variation 2% B+1% SB (T99B1SB1) with the value 0.995 kg/cm2. This study shows that stabilization material used in this research can be an alternative material for soil stabilization.

Investigation of the combination of microwave heating and calcium alginate capsule rejuvenation healing methods for cold mix asphalt considering the type of compaction effort

Healing behavior of asphalt mixes can affect the pavement life and life cycle cost. Effects of encapsulated rejuvenators and microwave heating methods (as two approaches to improve self-healing behavior) on the cold mix asphalt (CMA) were studied separately and simultaneously at different compaction conditions (i.e., different types and levels of compaction). For this aim, capsules of calcium alginate (CAG) loaded with waste sunflower oil (WSO) and waste engine oil (WEO) were used as encapsulated rejuvenators and iron (Fe) powder was used as a heat conductive material to spread microwave heating into the samples. Moreover, the synergetic effect of powder-based heat-absorbing additives and encapsulated rejuvenators on the healing performance (HP) was also investigated. The chemical test results showed that the Fe powder is compatible with the bitumen emulsion. Pre- and post-healing semi-circular bending (SCB) fracture experiments were conducted before and after healing to check for the effect of the healing method and compaction effort on the HP of CMA. The results indicated higher effectiveness of the microwave heating rather than the encapsulated rejuvenators for facilitating the healing of cracked areas in asphalt mixes. Combining microwave heating and encapsulated rejuvenation methods was not successful in improving the HP, and the healing index was reduced 10 to 15% when both methods were combined. Compaction condition was more influential than the healing method, and the adverse impact of inadequate compaction could not be compensated with any healing methods. It was shown that the healing index can be improved by more than 10% when a proper compaction was applied to the specimens.

Evaluation of asphalt pavement maintenance using recycled asphalt pavement with asphalt binders

Road maintenance projects require innovative, economical, and environmental solutions. This study evaluated recycled asphalt pavement (RAP) as a greener aggregate alternative to natural aggregate for the maintenance of asphalt concrete in flexible pavements. The mechanistic performance of warm mix and cold mix asphalt concretes using recycled asphalt pavement (RAP) was furthermore investigated in this study. The bitumen binders used were asphalt cement AC60/70 for warm mix asphalt concrete and asphalt emulsion CMS-2 h for cold mix asphalt concrete. Laboratory tests undertaken include Marshall stability and flow, indirect tensile strength, indirect resilient modulus, indirect tensile fatigue, and permanent deformation were performed to ascertain the true performance of RAP-AC60/70 and RAP-CMS-2 h mixtures as maintenance asphalt concretes. The laboratory test results of RAP-AC60/70 and RAP-CMS-2 h mixtures were compared with those of a conventional warm mix asphalt concrete using limestone and asphalt cement AC60/70. The results indicated that the overall performance of both RAP-AC60/70 and RAP-CMS-2 h mixtures was comparable to the Limestone-AC60/70 mixtures. The total material cost of RAP-60/70 and RAP-CMS-2 h mixtures was approximately 60% lower than Limestone-AC60/70 mixture. However, the RAP-CMS-2 h mixture had more advantages than RAP-60/70 in terms of maintenance operation and carbon footprint emission. The usage of RAP with both CMS-2 h for repairing pavement deterioration was found to provide a more cost-effective and greener solution.

Development of a novel infrared methodology to assess the degree of blending in cold and warm recycled asphalt mixtures incorporating a bituminous or bio-based virgin binder

2/3 of the reclaimed asphalt pavement (RAP) amount is used for recycling of European asphalt mixtures. An issue that remains unresolved is the blending between the RAP binder and the new binder. Using infrared microscopy, the binder blending is assessed in low-energy mixtures using a bituminous or bio-based binder. Infrared data were acquired and quantified using average and standard deviation indicators; their evolution is monitored over 3 months. A relationship between the average and the binder concentration is highlighted. Binders homogeneity depends on the RAP content and virgin binder. On cold mixes, infrared data evolve over time, highlighting emulsion curing.

Cold mix asphalt with polymeric stone for low traffic volume roads

The use of polymer-based household waste in the wearing course of flexible pavements has been analysed, either as an asphalt bitumen modifier or as a dry additive. However, there are not enough records in which this waste is used to make up the aggregate to be used in an asphalt mix. This article presents the development carried out at LEMaC, consisting of pieces made from the mixture of household waste polymers and soils, which has been called Polymeric Stone. This material is used to design a cold-mix asphalt, and its use has been validated after evaluating a series of properties.