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... However, the soaked conditioning at 60°C for 24 h may be too harsh for CBEM due to the high air void and inappropriate curing. As a result, the AASHTO T 283 (2022) was utilized with specific alterations as suggested by past studies (Ling 2013, Daneshvar et al 2020 ...
Rutting is a worldwide recognized distress in bituminous pavement caused by repetitive passage of traffic loads at high temperature. High air voids and poor early strength of cold bitumen emulsion mix (CBEM) can cause rutting deformation even at lower temperatures, making it undesirable to practitioners. The CBEM can be effectively modified by using hydraulic materials as filler. The present study examines the effect of ground granulated blast furnace slag (GGBFS) and lime as fillers on rutting characteristics of CBEM at varying temperatures (i.e., 40, 50, 60 °C). The conventional stone dust (SD) filler was partially replaced by GGBFS. For further modification, lime was added in CBEM containing GGBFS. Initially mix were selected for rutting test based on the results obtained by Marshall stability, indirect tensile strength, retained Marshall stability, and tensile strength ratio tests. Based on these results, 80% of GGBFS was optimized for CBEM production. Incorporating 20% lime with 80% GGBFS in CBEM further improved the properties mentioned above. Both mixes were selected for the rutting test, along with CBEM containing 100% SD and CBEM containing 20% lime, which were also selected for comparison purposes. Wheel tracking device was used for rutting test on CBEM at varying temperatures. Based on results, it was found that increasing testing temperature increases the rutting deformation. However, the CBEM containing GGBFS and lime by 80% and 20% of total weight of filler in the mix, respectively, gave better rutting resistance at each testing temperature and provide less temperature sensitivity. So, this paper introduces the blended GGBFS and lime as a new composition in CBEM that provides improved laboratory strength, moisture susceptibility resistance, and rutting resistance.
... Minimum voids attained by 50R mixes among three mixes show that there were more 50R bonds between the aggregate and binder than the other mixes. RAP material has more fines than cold mixes without RAP mixes; therefore, voids are filled with fines, and less stripping occurs due to moisture [49,50]. ...
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.
... Digital images of the mixtures before and after the boiling test were captured and subjected to image processing. Recent studies have provided several image processing methods to assess the experimental results based on ASTM D3625, turning the subjective observation into an objective measurement (5,44,45). In this study, a newly developed color image processing method was utilized to separate the aggregate pixels representing the stripped areas. ...
The surface energy of aggregate in asphalt pavements has a huge impact on its moisture susceptibility. The commercial antistripping agents widely used in asphalt may not be effective enough to enhance the moisture resistance if large quantities of acidic aggregates exist in pavements. This is also the reason why moisture damage is still an issue in many U.S. regions primarily supplied with ''problematic'' aggregates. In this regard, a promising solution is to use waste-plastic-coated aggregate, the surface of which is fundamentally modified and has a high affinity with asphalt because of the hydro-phobic nature of plastic. However, it has not been widely promoted in the industry since there needs to be a practical and reliable method for uniform coating and avoiding the agglomeration of fine aggregate. To this end, an entirely new coating technology (thermoplastic polyethylene powder coating [TPPC]) was developed to coat aggregate using polyethy-lene (PE) powder. This technology utilizes a cheap but highly wettable fluidized bed to stably disperse the hydrophobic PE powder. Then, the dispersion liquid is sprayed onto the hot aggregate where the fluidized bed will evaporate fast while the PE particles stay, melt, and coat the aggregate surface. The microstructures of the coated aggregate were directly observed by scanning electron microscopy. Surface energy-based thermodynamic parameters were used to demonstrate the effect of TPPC on the moisture resistance of asphalt mixtures. This technology can be extended to other types of waste plastic if suitable fluidized beds are developed.
... However, their applicability is somewhat limited due to their lower early strength. This is primarily due to the presence of water in the mixture, which interferes with the adhesion and cohesion properties of the binder [7][8][9][10]. Water in bitumen emulsion and adding water to dry aggregates before mixing with the binder are possible sources of water in CBEM. ...
... Ling and Bahia 2018 [31] introduced some new volumetric parameters, i.e., absorbed water volume by aggregates (VWA) and voids filled with water (VFW), based on different phases for CBEM with other parameters of HMA, i.e., air void (VA), total binder volume (VB), absorbed binder volume (VBA), effective binder volume (VBE), voids in mineral aggregates (VMA) and voids filled with bitumen (VFB). The volumetric parameters of CBEM are expressed from equation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12), corresponding to both phases. Where ITS s and ITS u are the averages ITS value of soaked conditioned samples and unsoaked conditioned samples in kPa, respectively. ...
Cold bitumen emulsion mix (CBEM) is an emerging sustainable material for constructing the base or surface layer of flexible pavements, reducing energy consumption and global warming effects compared to hot mix asphalt. The main challenges associated with CBEM are low initial strength, moisture susceptibility, etc. This is primarily due to water encapsulation. The curing process allows the water to evaporate gradually over time, improving mechanical properties. This study investigates CBEM’s volumetric and mechanical properties under different curing conditions. CBEMs were prepared using low (50 blows) and high (75 blows) compaction efforts and cured at 25, 40, and 55 °C for 1 to 28 days. In volumetric characteristics, the air voids and voids in mineral aggregates decreased slightly with curing, while total binder volume decreased. Effective binder volume and voids filled with binder increased slightly, then decreased. The mechanical properties, i.e., Marshal Stability, Marshal Quotient, Indirect Tensile Strength (ITS), and Moisture Susceptibility parameters like the Indirect Tensile Strength Ratio (ITSR) and Retained Marshal Stability (RMS), were found to improve over time at each curing temperature. Using a high curing temperature further improved the mechanical characteristics of CBEM. The curing process was decelerated in case of CBEM prepared by high compactive efforts compared to CBEM prepared by low compactive efforts. The Michaelis-Menten model can be used to analyze moisture loss growth and the development of mechanical properties over time. The strength-maturity model can be developed by using ITS as strength parameters. There was a strong correlation between all mechanical characteristics and moisture loss.
... However, CMA mixtures have been reported to have low early strength and high porosity (Al-Busaltan et al. 2017). This inadequacy can be because of the presence of water in cold bitumen emulsion (Ling 2013). Attempts have been made to improve mechanical properties of CMA mixtures using hydraulic binder like lime and cement (Niazi and Jalili 2009). ...
The generation of waste materials is a global concern and attempts are being made to utilize these wastes in the construction industry. The development of road infrastructure everywhere is going at a fast pace which increases the environmental degradation, fossil fuel consumption, global warming, and depletion of natural materials because of hot mix asphalt (HMA) usage. The detrimental effects of generation of waste in large quantities at a global scale and virgin material/energy consumption in HMA construction are of prime concern and need to be addressed. The construction/maintenance of pavement must be environmentally, economically, and socially sustainable. Use of cold bitumen emulsion mixtures (CBEMs), a type of cold mix asphalt (CMA), is a way forward for development of sustainable road infrastructure. The incorporation of wastes in CMA can be a sustainable solution to problems linked to waste generation and development of flexible pavements with HMA. This work summarizes the staging evaluation of CBEMs incorporated with waste glass (WG) and fly ash (FA) utilizing mechanical characteristics, water sensitivity and environmental impact, critical gaps in the literature, and recommendations to address those gaps. A detailed analysis on CBEMs using WG as a replacement of fine aggregate showed comparable stability/stiffness and multifold resistance to rutting than HMA. Fly ash filler in CBEMs reported extraordinary increase in stability, stiffness, rutting resistance, and water sensitivity than reference CBEM/HMA. The focus of the research area should continue on the exploration of waste materials for use in CBEMs to achieve a better environment for society and to promote sustainability in the pavement industry.
... Similarly, the intensity of grey images ranges from 0 to 255 (Fig. 2b). During the binary image conversion, a threshold value should be chosen, and the intensities of pixels higher the threshold value will be converted to 255 (pure white) while the intensities lower than the threshold will be changed to 0 (pure black) (Fig. 2b) [19,33]. ...
... In a recent study by [40], the k-means clustering and machine learning-based classification were utilized to estimate the coating quality of asphalt on aggregate. Although this method was conducted to analyze the samples by static immersion method, the test specimens by static immersion and boiling water test are actually similar [6,33]. Therefore, the new image processing method can still be used to analyze the loose mixtures tested by boiling water test. ...
Boiling water test (ASTM D3626) has been utilized to investigate the moisture susceptibility of asphalt mixture for decades. It was originally intended to compare the relative moisture resistance of a few mixtures, and the degree of stripping after the boiling was recorded based on visual observations. In recent years, several digital imaging-assisted modified boiling tests have been proposed, which significantly improved the accuracy of test results. This paper reviewed the recent advancements (2009–2022) in different test methods by digital imaging. The limitations and challenges of each method were also discussed and compared to each other. In addition, further experiments were performed to investigate the effect of aging, boiling time and water quality on the coating ratios. The boiling test results of sixty loose mixtures were compared to the tensile strength ratios (TSRs). Based on the results, the boiling water test with enhanced accuracy by image processing can be potentially developed as a measure of field performance. More importantly, the test should be conducted immediately after the mixing of asphalt and aggregate, and the aging of asphalt mixtures could significantly increase the results of coating ratios up to 100%, which made the boiling test unable to identify moisture susceptibility. It was found that the boiling water could not strip asphalt from aggregate after a long time of aging even though the moisture damage occurred and weakened the bond between asphalt and aggregate. In addition, the water quality could considerably influence the boiling test results, and the use of distilled water might underestimate the moisture damage of asphalt mixtures subjected to acid rain.
... The average time required to prepare the tight specimens is about 3 h, while the loose specimens can be prepared in less than 1 h. The percentage of gaps between the aggregates for each specimen was quantified using the image processing technique recommended by Ling (2013) and Saghafi et al. (2019). Based on the binary images, 3% of the area of the tight specimen and 8% and 10% of the two loose specimens were comprised of voids. ...
AASHTO has provisionally endorsed the use of a three-wheel polishing device (TWPD) for polishing and the dynamic friction tester (DFT) for measuring the friction of the coarse aggregates used in hot mix asphalt (HMA). Despite ample studies showing the feasibility of such a system for HMA specimens, research efforts related to quantifying the coarse aggregates that are used in those mixes have been less common. The results of a study to accelerate the test and to decrease the tedium of specimen preparation for aggregates are reported here. Three identical TWPD devices that complied with the AASHTO provisional specification were fabricated. A new specimen preparation method was introduced to reduce the associated time and cost. Several operational parameters that can impact the repeatability and repro-ducibility of the process, such as tire type and tread condition, specimen preparation, and DFT rubber pad thickness, were investigated. This study verified that the TWPD/DFT test method can delineate the polishing/friction performance of different aggregates with acceptable repeatability and reproducibility. The TWPD/DFT test time and cost can potentially be decreased considerably by using the proposed practical and analysis modifications.
... CBEMs will offer weak early strength and raise in porosity [6], [7]. The disadvantages that mentioned it can be attributed to the presence of water in the mixture [8]. So their uses are very limited due to the long period needed for such materials to arrive on their full strength after paving. ...
Cold mix asphalt is bituminous material that produced at ambient temperatures. Many advantages can be obtained from cold mix asphalt especially, economic and environmental aspects this come from no need to heat of aggregate and bitumen for purpose the production and laying mix which are remain necessary demand to hot mix asphalt production. However, cold mix asphalt show inferior performance at early life and high porosity. This lab investigation focuses on improving the Cold Bitumen Emulsion Mixtures (CBEMs) containing 2% ordinary Portland cement (OPC) by adding Sugar industry Waste (SW) with different percentages i.e. 2, 4, 6 by total mass of aggregate. The optimum SW content was selected based on Indirect Tensile Strength (ITS) test which was 4%. ITS for the modified mix increased significantly to more than 55% and 32% in comparison with the untreated mixtures and CAEM with 2% OPC, respectively. On the other hand, the results of tests for Marshall Stability (MS), Marshall flow (MF) and index of retained strength (IRS) tests were encouraged. The value of MS and MF for mixtures with 4% SW increased about 140% and 38% respectively while, IRS improved about 45% in comparison with untreated mix. Finally, this research has gave highly improved cold bituminous emulsion mixtures (CBEMs) with SW in addition to environmental and economic benefits.
... Among different green technologies, the use of cold mix asphalt (CMA) in the pavement surface layer has gained increasing popularity in recent years. Lower energy consumption in asphalt production phase, reduced greenhouse gas emissions, improved safety working conditions, possibility of storing mixture after production, and ease of use are among the major benefits of CMA compared to HMA and WMA technologies (Gómez-Meijide & Pérez, 2014;Ling, 2013). According to Chappat and Bilal (2003), the total energy needed to prepare a ton of hot mix asphalt (HMA) is 680 MJ, while CMA requires 457 MJ per ton, which is approximately 33% reduction in energy consumption. ...
... They also estimated that a ton of HMA produces 54 kg of pollutants and greenhouse gas emissions, whereas it is 36 kg per ton for CMA. However, it should also be noted that low early-life strength, stiffness and creep modulus, long curing time, high porosity of the compacted mixtures and high moisture susceptibility are the main drawbacks of the CMAs restricting their application only to low traffic roads and walkways (Ling, 2013;Needham, 1996). ...
... Physical properties of aggregates are presented in Table 1. Due to the weak resistance of CMAs against moisture damages, dense-graded gradation was used to provide more durability by preventing water ingress into the mixture (FHWA 128, 2001;Ling, 2013). As shown in Figure 1, the aggregate gradation used in this study complies with the ASTM D 4215-07 (2013) specification. ...
Due to environmental and economic advantages, cold mix asphalt (CMA) can be considered as a good alternative to conventional hot mix asphalt (HMA). Nevertheless, it has inferior performance compared to HMA, so that the application of CMA is not recommended in the surface layer of pavements subjected to high traffic volume and/or regions with very cold or hot climate. Considering the high potential of distress occurring in the CMAs, this research is aimed at investigating the effect of crumb rubber (CR) on fracture and moisture damage resistance of the CMAs. Different CR percentages were applied through two different modification methods and, then by means of Semi-Circular Bending (SCB) test, the fracture energy and flexibility index (FI) of modified CMAs were obtained and compared with the unmodified HMA and CMA. The moisture sensitivity of the modified CMAs was also evaluated using modified AASHTO T 283. Moreover, the effects of the addition of cement along with CR were investigated. The results show that simultaneous use of 14% CR and 2% cement in the CMA can considerably improve the fracture and moisture damage resistance so that it has comparable performance to the conventional HMAs.
... Water sensitivity of cold mix is measured by indirect tensile strength ratio (ITSR), indirect tensile stiffness modulus ratio (SMR) and boiling test Ling et al., 2013Ling et al., , 2014Ling et al., , 2016Niazi and Jalili, 2009). Moisture susceptibility and durability are the main problem in cold mix due to presence of water in mix (Cheng, 2013;Khalid and Monney, 2009;Yilmaz and Sargin, 2012). CMA shows higher permanent deformation and moisture susceptibility (Schmidt et al., 1973). ...
Global warming is one of the biggest challenges that we are facing today. The construction industry is also contributing to the problem by emitting greenhouse gases. In order to deal with this issue, sustainable products are being adopted by all the industries. Similarly, the highway industry is also adopting several measures to reduce its carbon footprint. One of such measures is cold mix asphalt technology (CMA). CMA does not require any heating of the material. This is achieved by using asphalt emulsion and cutback as binding material. Since these materials are liquid at room temperature, they do not require any heating for mixing and compaction. This gives many environmental and economic benefits to CMA over hot mix asphalt (HMA). Despite having these advantages, the inferior performance makes CMA undesirable to be used in the construction of roads having high density traffic. Although some studies have been taken to improve the performance of CMA but those are limited in their scope. The present paper gives an overview of the different aspects of CMA technology. It discusses materials, design procedure, field utilisation, performance, effect of different performance enhancing measures of CMA. In the end benefits, drawbacks, and future scope of CMA are also presented.
