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One of the primary causes of premature pavement deterioration in Asphalt Concrete (AC) mixtures is the breaking of the adhesive bond between the aggregate and the binder. The purpose of this study is to assess the performance characteristics of AC mixture utilizing the Rediset LQ-1200 additive. In order to achieve this goal, tests such as the Marshall Stability (MS), Marshall Stability Ratio (MSR), Indirect Tensile (IDT), indirect tensile cracking, and Wheel Tracking (WT) were deployed to evaluate the mechanical properties of AC mixtures. The findings demonstrated a considerable improvement in the physical parameters of the AC mixture with the Rediset LQ-1200 additive compared to the base AC mixture. The MS and MSR were improved by about 28% and 13%, respectively, while the AC mixture's resistance to rutting and cracking was efficiently increased. [ABSTRACT FROM AUTHOR]

Buton Asphalt is natural asphalt originating from Buton Island (Indonesia), with the potential deposit amount reaching up to 662 million tons. This substantial domestic mining potential must be utilized for domestic road needs and to boost the country's economy. However, Buton asphalt's utilization is minimal compared with imported oil asphalt, which reached a usage rate of up to 94 % in 2022. Therefore, as a form of a solution-oriented policy, Buton asphalt is included as one of the 21 commodities in the Strategic Roadmap for Downstream Investment in Indonesia, followed by various supportive regulations for developing this Buton asphalt product. One of the leading products the government targets is natural pure Buton asphalt. This product consists of >99 % bitumen content after extraction, also called Pure Buton Asphalt. The idea was to modify pure Buton asphalt with coconut coir to increase the Marshall Stability and Dynamic Stability values to make the asphalt mixture more resistant to vehicle loads and rutting. The tests were conducted to determine the optimum asphalt content (OAC) of the mixtures, Marshall's Stability comparison, and the dynamic stability test using a Wheel Tracking Machine to identify the comparison of permanent deformation. This study analyzed the Marshall characteristics and dynamic stability characteristics with variations in coconut coir content of 0.5 %, 0.75 %, and 1 % by weight of asphalt and variations in coconut coir length of 0.5 cm, 1 cm, and 1.5 cm. Based on the results of this study, the optimum asphalt content in this study is 6.76 %, where pure Buton Asphalt modified with coconut coir has an increase in Marshall's stability value and dynamic stability value compared to pure Buton asphalt without additional coconut coir [ABSTRACT FROM AUTHOR]

The study evaluated and compared the influence of bitumen modification for sustainable as- phalt using waste plastic (Polyethylene Terephthalate, PET) and waste Polystyrene (PS) at 5–50% modification levels. Rice husk ash (RHA) and desilted sand were used as filler and fine aggregate with crushed granite as coarse aggregate. Tests conducted include; penetration, viscosity, flash point, fire point, specific gravity, ductility and marshal stability test on asphalt. For PET modi- fied-binder a decrease in penetration and ductility was observed while the specific gravity, vis- cosity, flash and fire points of the binder increased. For the PS modified-binder, the penetration, ductility, viscosity and specific gravity decreased with an increase in PS while the flash and fire point increased. Marshall Stability results showed an optimal of 20% PET modification was ade- quate for medium traffic surfaing with stability, flow, density, air void, void in mineral aggregates (VMA), and Void filled with binder (VFB) of 4875N, 3.53 mm, 2.460 g/cm3, 3.30%, 18.20%, and 81.87% respectively. For 10% PS modification content, the stability, flow, density, air void, void in mineral aggregates (VMA), and Void filled with binder (VFB) were found to be 6825N, 3.33 mm, 2.362 g/cm3, 4.52%, 18.21%, and 75.18% respectively which was found to be adequate for heavy traffic surfacing. Hence, it was concluded that the investigated waste plastics could be used in Asphalt pavement courses. If applied, these results could provide low-cost materials for paving roads while also reducing waste-related pollution and environmental issues.

Cold emulsion asphalts have advantages and disadvantages. The advantages of this type of mixture are related to the low temperature of production, environmental considerations, and its portability to long distances. One of the main reasons for the poor performance of this type of asphalt is its moisture content. The water penetration hinders the fracture of emulsion bitumen, and after that, the mixture's resistance to moisture is reduced. The present research used the modified Marshall method to determine the optimal bitumen percentage. For this reason, one to three percent by weight of the asphalt-cement mixture and 0.3 to 0.5 percent by weight of fiber mixture containing fatty arbocell were added. The resulting samples were subjected to the Marshall strength, Marshall index modified Lottman and Nicholson tests. Based on the results, the Marshall strength was 47.88%, the Marshall index was 139%, adhesion was 41%, the ratio of indirect tensile strength was 21%, and the fluidity was 36.47%. According to the data obtained from this research, it is suggested that 3% cement and 0.3% fatty arbocell fibers should apply in cold asphalt mixtures.

In the present study, various soft computing techniques were employed for predicting the Marshall stability (MS) of asphalt concrete reinforced with polypropylene fibre, namely Multiple Linear Regression (MLR), Reduced Error Pruning (REP), Random tree (RT), Random Forest (RF), M5P_pruned and M5P_unpruned-based models, and the performance of these models was evaluated statistically. A total data set of 138 samples has been collected from various reliable and authentic published experimental researches, out of which 96 samples are used for training and 42 samples for testing using 70:30 split ratio. For each soft computing technique, coefficient of correlation (CC), Wilmott index (WI), mean absolute error (MAE), root-mean-square error (RMSE), Nash–Sutcliffe model efficiency coefficient (NSE), scattering index (SI) and mean absolute percentage error (MAPE) were calculated as the statistical indicators for analysing the performance of each soft computing technique. The RF model's dominance over the other models was confirmed by statistical indicators with values of CC as 0.9141, WI as 0.950, MAE as 1.1028, RMSE as 1.661, NSE as 1.0006, SI as 0.12077 and MAPE as 7.802, while the RT model also has shown competitive prediction ability over the M5P_pruned and M5P_unpruned, REP and MLR models. A sensitivity analysis presented that the bitumen content was the most effective parameter for predicting the Marshall stability using RF-based model. The results of this computational evaluation clearly showed that the applied soft-computing technique was capable of accurately calculating the Marshall stability of the asphalt concrete. [ABSTRACT FROM AUTHOR]

This research discusses the asphalt mix design with electronic waste aggregates. Plastic is increasing day by day and it is an environmental hazard. Its disposal is a very serious issue. Electronic Waste can cause adverse effects on the environment. To deal with this problem we used Electronic Waste as a replacement for natural aggregates. In this research we used electronic waste in place of natural aggregates upto15%. We prepared 6 samples with 0,5,10 and 15% E-waste and performed Marshall Stability and Flow test. We also performed Bulk Specific gravity test. The Marshall Stability value at 0% is 1262.53kg, 5% is 1256.4kg, 10% is 1230.32kg and 15% is 1204.24. The Flow value at 0% is 7.5mm, 5%is 7.86mm, 10% is 8.1mm and 15% is 8.5mm. The bulk specific gravity at 0% is 2.324, 5% is 2.236, 10% is 2.091 and 15% is 2.027. The Marshall Stability and bulk specific gravity decrease with an increase in E-Waste% while Flow value increase with increase in E-Waste%. [ABSTRACT FROM AUTHOR]

Pavement engineering has always relied on asphalt concrete as the primary material. As a result, increasing the quality of asphalt concrete for greater performance and longer durability has remained a focus of research. The present paper aims to assess the potential of soft computing-based models, such as Artificial neural networks, Support vector machines, Gaussian process, M5P tree, Random forest, and Random tree-based models, used for the prediction of Marshall Stability of carbon–fiber asphalt mix. Five different statistical indices are used to evaluate the performance of each model with different input variables, such as Bitumen content (BC), Carbon fiber (CF), Bitumen grade (VG), Fiber length (FL), and Fiber diameter (FD), Specific gravity coarse aggregate (SG(CA)), Water absorption coarse aggregate (WA(CA)) and Specific Gravity of bitumen (SG(B)), to get the Marshall Stability (MS) as an output. Five statistical indices were used to assess the effectiveness of the applied models i.e., Coefficient of correlation (CC), Mean absolute error (MAE), Root mean square error (RMSE), Relative absolute error (RAE) and Root relative squared error (RRSE). According to performance evaluation results, it has been found that the ANN-based model has outperformed all the applied models for predicting the Marshall Stability of asphalt concrete using carbon fiber with CC value as 0.9287 and 0.9126, R2 value as 0.8624 and 0.8328, MAE value as 1.7527 and 1.8702, RMSE value as 2.3305 and 2.4438, RAE value as 32.51 and 39.64% and RRSE values as 37.30 and 43.59% for both the training and testing stages respectively. Taylor's diagram suggests that the ANN model outperforms the other applied models. Sensitivity analysis shows that the bitumen content (BC) is the more sensitive parameter in the carbon–fiber asphalt mix. Furthermore, carbon fiber is comparable to the sensitivity of the bitumen content which shows the significance of the carbon fiber in the asphalt mix in predicting the Marshall Stability. [ABSTRACT FROM AUTHOR]

Cold emulsion asphalts have advantages and disadvantages. The advantages of this type of mixture are related to the low temperature of production, environmental considerations, and its portability to long distances. One of the main reasons for the poor performance of this type of asphalt is its moisture content. The water penetration hinders the fracture of emulsion bitumen, and after that, the mixture's resistance to moisture is reduced. The present research used the modified Marshall method to determine the optimal bitumen percentage. For this reason, one to three percent by weight of the asphalt-cement mixture and 0.3 to 0.5 percent by weight of fiber mixture containing fatty arbocell were added. The resulting samples were subjected to the Marshall strength, Marshall index modified Lottman and Nicholson tests. Based on the results, the Marshall strength was 47.88%, the Marshall index was 139%, adhesion was 41%, the ratio of indirect tensile strength was 21%, and the fluidity was 36.47%. According to the data obtained from this research, it is suggested that 3% cement and 0.3% fatty arbocell fibers should apply in cold asphalt mixtures. [ABSTRACT FROM AUTHOR]

Basalt Fiber Asphalt Concrete (BFAC) is an environmentally friendly and durable material with potential road, bridge, and infrastructure construction applications. This study investigates the application of Machine Learning (ML) models, specifically the classical Gradient Boosting (CGB) algorithm, in conjunction with metaheuristic algorithms, to predict the Marshall Stability (MS) and optimize the design of BFAC mixtures. The model is trained and tested on a comprehensive dataset of experimental samples, taking into account various input parameters, including basalt fiber (BF) properties, asphalt binder characteristics, and aggregate gradation. Hyperparameter tuning is employed to enhance the model's predictive performance using metaheuristic algorithms such as Particle Swarm Optimization (PSO), Hunger Games Search (HGS), and Bald Eagle Search (BES) and compared regarding the convergence and computational efficiency. The findings demonstrate that BES outperforms other algorithms, achieving the highest performance. The CGB-BES model is then applied to three optimization scenarios, focusing on maximizing the MS while minimizing BF and asphalt binder content. Post-processing and interpretation of the results reveal the importance of combining ML and materials engineering expertise. By highlighting the synergy between CGB-BES model and domain-specific knowledge, materials engineers can effectively optimize the mixtures and improve the design and performance of BFAC.

Stone mastic asphalt is a type of hot mix asphalt that requires much coarse aggregate, so substitution waste aggregate, such as steel slag, will be an economic reason. The problem is that there are still many things that have not been consistent in various studies related to the moisture resistance of steel slag. The study aimed to compare the effect of CA(OH)2 on the moisture resistance of the steel-slag stone mastic asphalt mixture and to determine the optimal CA(OH)2 dosage for improving the mixture resistance. This study employs basalt aggregate, steel slag from Krakatau Steel Company, 60/70 penetration asphalt, a stabilizing substance made of bamboo fiber, and CA(OH)2. The Texas boiling and the static immersed methods are used to test the adhesion on a loose mixture. The retained Marshall stability and indirect tensile strength are used to test the adhesion on the compacted mix. Testing result of Krakatau steel slag shows that steel slag has a much higher Fe2O3 content than steel slag in general and has low water absorption; a poor affinity for asphalt results from this. The result of the Texas boiling method showed a decrease in the percentage adhesion value between steel slag and asphalt compared to natural basalt aggregates and asphalt. Marshall Stability Ratio and Tensile Strength Ratio increased after mixing the asphalt with CA(OH)2. Marshall test results show decreased stability in mixtures with steel slag substitution. Adding CA(OH)2 increased stability and resistance to moisture significantly. This indicated that CA(OH)2 enhances moisture resistance on stone mastic asphalt with modified steel slag. Stability, Marshall stability ratio, indirect tensile strength ratio, particle loss, and Texas boiling test significantly improved with adding CA(OH)2. [ABSTRACT FROM AUTHOR]

With rapid increase in energy consumption around the world, usage of petroleum-based products has also been on the rise. Bitumen, a product of petroleum distillation is being widely used as the pavement material all around the world. Petroleum being a non-renewable source of energy and also an environment pollutant, there must be an alternative way to reduce its consumption. India is the world's largest producer of waste, specifically biowaste. Many industries are reducing the amount of waste in the atmosphere, which pollutes the environment. That is also why we use this waste as a substitute material for pavement construction. Sugar cane biowaste is 100 million metric tons per year produced, and that is why we use pyrolysis, which is the process of transforming biowaste to biochar using a binder as flexible pavement construction. This study aims to find out alternate materials in flexible pavement construction, focused on one potential replacement: Biochar, which is produced through pyrolysis of sugarcane waste. Biochar is replaced with bitumen in 0%,5%,10%,15%, and 20% and then tested to validate the performance of the Marshall specimens. However, it is important to ensure that the biochar used in the process meets the required standards for road construction. Henceforth the test results are evaluated on key properties like stability, flow and mix density. [ABSTRACT FROM AUTHOR]

Split Mastic Asphalt (SMA) is an open-graded mixture with a high filler content. There have been many types of additives used in an effort to improve the performance of mixtures. Limestone is one of the filler options for asphalt pavements and is a mineral resource that has a large amount in Indonesia, estimated at 2,160 billion tons [1]. There were three types of lime used in this study, abundantly available in west Sumatra, i.e. Palupuh (PL), Kamang Mudiak (KM) and Padang Panjang (PP) lime. The significance of this study is to determine the effect of each replacement filler on the characteristics of the split mastic asphalt 0/11 (SMA 0/11) mixture based on the Marshall test. PP lime with a lime content of 7% and an asphalt content of 6.7% to 7% produced the highest stability value of 1,020.0 kg. Thus, it can be concluded that PP lime is the most suitable as a filler for SMA pavement and PP lime content of 7% has a high stability value and other Marshall parameters has followed to the standards required. [ABSTRACT FROM AUTHOR]

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In this study, an attempt has been made to assess the influence of Corn Cob Ash (CCA) as filler in asphalt concrete mix. The effect of corn cob ash on mechanical properties of the asphalt concrete such as Marshall stability, flow, volumetric properties, and indirect tensile strength of asphalt concrete for heavy traffic roads has been evaluated. A total of thirty (30) asphalt concrete specimens were prepared with basaltic stone dust (BSD) and corn cob ash as a filler with bitumen content between 3.5% and 5.5% at varying increments of 0.5% and the Marshall stability test was performed on full mixes to determine the Optimum Bitumen Content (OBC) of the mixtures. From the test results, it is seen that specimens made with corn cob ash and basaltic stone dust are found to have satisfactory Marshall properties and moisture susceptibility showed that mixes using CCA filler provide better resistance to moisture effect than mixtures using BSD filler. Optimum bitumen content of CCA, and BSD were found out as 4.69%, and 4.86%, respectively. It is seen that maximum stability is observed by CCA filler materials. The value of stability of the asphalt concrete mixture using CCA and BSD is 11.4kN and 10.9kN, respectively, which satisfies the limiting value of 8.006 kN. Research findings indicated that the Indirect Tensile Strength Ratio (ITSR) of the paving mixes using basaltic stone dust was 93.71%, and corn cob ash was 97.04% which satisfies the criteria provided in the Ethiopian Road Authority (ERA) and Asphalt Institute Standard Specifications. Hence, it is generally concluded that the corn cob ash can effectively be used as filler in paving mixes in place of the most commonly used filler such as basaltic stone dust. Corn cob ash is a viable agriculture waste product that can be used as filler materials in the production of asphaltic concrete for heavy-trafficked roads. Overall, the use of corn cob ash as filler in hot mix asphalt concrete partly solves the significant agricultural waste disposal problem of the environment. [ABSTRACT FROM AUTHOR]

Marshall properties are one of the major requirements for designing hot asphalt mixtures. These properties need to be evaluated to make sure that asphalt pavement performs well over its service life. The evaluation of the Marshall properties of asphalt mixtures containing coarse recycled concrete aggregates (RCA) was the study's main target. RCA properties differ from virgin aggregate in the presence of cement mortar. To improve RCA properties, two methods were adopted. The first, termed pre-soak treatment, consisted of soaking RCA in acetic acid for 24 hours at a concentration of 0.1 M. The second one, termed mechanical treatment, involved placing RCA inside the Los Angeles machine with balls and running it for 500 cycles. RCA was incorporated into asphalt mixtures at percentages 20, 40, 60, 80, and 100% of coarse virgin aggregate. The results of the study showed that replacing virgin aggregate with RCA led to economic feasibility. Despite the amount of asphalt binder increasing as coarse RCA content increased, the characteristics of HMA were not significantly altered except for Marshall stability. The maximum increase in Marshall stability happened in the mixture containing 60% untreated RCA; it was 14.78% greater than the control mixture. [ABSTRACT FROM AUTHOR]

This study investigates the effect of carbon fibers when added to HMA containing recycled concrete aggregate on Marshall properties. It is included to identify the optimum asphalt contents according to the Marshall design method for mixtures containing 20, 40, 60, 80, and 100% coarse recycled concrete replaced with coarse virgin aggregate. Two lengths of 10 and 20 mm of carbon fibers had been added with three percentages of 0.15, 0.25, and 0.35% to the total weight of the mixture. The results showed all mixtures containing recycled concrete aggregate met SCRB 2003 Iraqi standard requirements for wearing coarse type IIIA. Replacement of virgin aggregate by recycled concrete aggregate led to an increase in optimum asphalt contents, in which the maximum increase reached 10.78% over the control mixture when 100% of coarse recycled concrete aggregate was utilized. The Marshall characteristics were altered with carbon fiber, which increased stability. The highest level of stability reached about 38.89% over the control mixture when using 60% recycled concrete aggregate and reinforced by 0.35% carbon fibers had a length of 20mm.

In this research, the properties of two tailings solvent recovery unit (TSRU) samples, one bitumen froth sample and two aggregates, are evaluated using various laboratory tests. The TSRU-modified mixtures are prepared at different concentrations of bitumen froth (0%–6% of weight of mixture increasing in 1% intervals) where TSRU materials were added based on optimum moisture content of the mixture. The properties of the mixtures are investigated using indirect tensile strength and Marshall stability tests. The results show that TSRU modification results in a higher tensile strength. The granular layer thickness can be reduced by 42% and 60% for modified samples made with both aggregates. It should be noted that the modified samples fail to meet the soaked indirect tensile strength requirement. A potential solution to improve the indirect tensile strength of the soaked mixture is using cementitious additives such as Portland cement. [ABSTRACT FROM AUTHOR]

The usage of polymer-modified asphalt binders has increased as a result of the significant increase in the number of conventional cars operating on Iraqi roads in recent years. This has resulted in increased strains being placed on pavement structures and materials. Global exploration has focused on the development of stabilizing Stone Mastic Asphalt mixtures for improved pavement behavior. Numerous effective efforts were made to stabilize stone mastic asphalt mixes with polymers and fibers. Iraq produces a considerable amount of waste polymer materials each year. Usually, they are sent to landfills for disposal. These wastes are dumped, occupying a sizable portion of landfill space and creating various serious environmental issues. The study focuses on how waste polymer additions, such as recycled plastic bottles, shopping boxes, and tire crumb rubber, affect the mechanical performance and durability of stone mastic asphalt mixtures. The mechanical performance attributes were assessed. It is evident from the findings that the drain-down amounts were within the permissible requirement range. The findings also showed that the indirect tensile strength, Marshall Stability, moisture damage resistance, and resistance for permanent deformation of stone mastic asphalt mixtures have all increased as a result of the use of waste polymer components. The recycled polymer-modified mixes are the combinations that are most resistant to rutting, according to the results of the repeated load axial creep tests. Iraq may have new options to employ the significant volumes of recycled polymers that are becoming accessible as a result of recycling waste polymers. [ABSTRACT FROM AUTHOR]

In the present work, an attempt is made to find the most suitable prediction model for Marshall Stability and the optimistic Bitumen Content (BC) in carbon fiber reinforced asphalt concrete for flexible pavements by performing Marshall Stability tests. Further the prediction analysis is performed by taking the cognizance of the published research articles. Twofold approaches are adopted; first, to find the most suitable model to predict the Marshall Stability and second to obtain the optimum binder content responsible for the highest strength. Further, to find the most suitable model for closer prediction of Marshall Stability, eighteen input parameters i.e., Binder Content (BC with fifteen variations); 4.20%, 4.30%, 4.50%, 4.90%, 5.00%, 5.10%, 5.15%, 5.20%, 5.23%, 5.30%, 5.34%, 5.40%, 5.50%, 6.00%, 6.50%, and three others i.e., Carbon fiber, Bitumen grade and Fiber length are applied in the modelling algorithm. Five Machine learning techniques viz., Support Vector Machine, Gaussian Process, Random Forest, Random Tree, and M5P model were employed to find the most suitable prediction model. Seven statistical metrices i.e., Coefficient of correlation (CC), Mean absolute error (MAE), Root mean squared error (RMSE), Relative absolute error (RAE), Root relative squared error (RRSE), Willmott's index (WI), and Nash- Sutcliffe coefficient (NSE) were used to evaluate the performance of the applied models. After performing modelling analysis, it has been found that the Random Forest-based model is outperforming amongst all applied models with CC as 0.9735, MAE as 1.1755, RMSE as 1.5046, RAE as 25.68%, RRSE as 26.93%, WI values as 0.9351, and NSE values as 0.9272 in the testing stage. The Taylor diagram of the testing dataset also conforms to the results of RF-based model. The sensitivity analysis demonstrates that binder content (BC) of about 5.0% has a significant influence on the Marshall Stability in the asphalt mix used with carbon fibers.

The temperature and stress caused by the load can be cited as two main parameters leading to breakage in asphalt pavement, especially rutting (permanent deformation). So, to reduce the problems of rutting of roads, several actions have been taken, including improving pavement quality and the structure design methods. The increase in the attention of respective engineers in the last few years to modify and improve the asphalt performance through providing different types of additives and replacing the raw materials of asphalt mixture with recycled materials to improve the environment and reduce the cost of modified pavement mixture. This study discussed the use of low-density waste polyethylene as an asphalt modifier in percentages of (2, 4, and 6) % by the weight of asphalt and their impact on the performance of asphalt mixtures at high temperatures. This study showed that using plastic waste (low-density polyethylene) as a bitumen modifier improved the performance of asphalt mixtures at different high temperatures. This was achieved by reducing the rut depth by (80.5) % and (82.3) % at temperatures of 50 C and 60 C, respectively, using low-density polyethylene waste at an optimum value of about 4% by weight of asphalt in addition to enhancing the Marshall stability by using this percentage of polymer.

In recent years, Open Graded Friction Course OGFC is becoming more common in some countries. It is applied to improve surface frictional resistance, minimize hydroplaning, reduce water spray, improve night visibility, and lower pavement noise levels. These functions are carried out primarily by removing water from the pavement surface during a period of rain. Also, it has many disadvantages which as poor resistance to permanent deformation, low fatigue strength, high stripping, and moisture susceptibility. The paper aims to investigate the probability of using Cellulose Fiber (CF) as a modifier to improve the properties of OGFC asphalt mixture. In this research, one type of asphalt grade (40-50) and one gradation (19 mm Maximum Aggregate Size MAS) were used. Three percentages of CF (2%, 4%, and 6%) were added to asphalt cement to obtain the modified mixtures. Optimum asphalt content was selected by evaluating the following criteria: air voids content, asphalt drain down, abrasion resistance, and permeability. Several laboratory tests such as Indirect Tensile Strength (ITS), moisture susceptibility, Marshall stability, and flow were evaluated for modified samples, and their results were compared to the original open-graded asphalt mixture. The outcomes indicated that cellulose fiber greatly enhanced the mechanical properties of OGFC mixtures, increasing moisture damage resistance by 19.4%. Furthermore, Marshall stability improved by 38.92 % as the abrasion loss is decreased by 15.85% with adding of CF for aged samples.

Increased production of wastes from different companies and agricultural areas creates severe surrounding trouble in terms of management and removal in Ethiopia. The utilization of agricultural waste products and residue in construction work is an excellent alternative solution in reducing the solid waste disposal problem of the environment. In this research, the application of maize cob ash (MCA) in asphalt concrete production is investigated as filler material in hot mix asphalt for binder course. Physical and chemical tests were investigated for MCA. Asphalt specimen prepared using crushed stone dust (CSD) as filler without maize cob ash used as a control material. The content of CSD filler was replaced with MCA at a rate of 0%, 25%, 50%, 75%, and 100% by weight of CSD. A total of thirty (30) mix specimens were prepared, fifteen asphalt concrete samples were prepared by a 6% of CSD as filler by weight of aggregate with bitumen content between 4.5 and 6.5% at varying increments of 0.5% by total weight of the mix to determine the optimum bitumen content (OBC). The remaining specimen was prepared at 5.30% OBC to find out the optimum replacement rate of MCA. The values of Marshall stability, flow, unit weight, air voids, and voids in mineral aggregate and voids filled with asphalt at 75% replacement of CSD with MCA were, 11.7 KN, 3.13 mm, 2.360 g/cm3, 4.0%, 14.58%, and 72.56%, respectively. Research findings indicated an optimum value of MCA could be replaced the CSD is 75% by weight of CSD filler or 4.5% (by weight of aggregate in the production of hot mix asphalt binder course for heavy-trafficked roads. Results also indicated that agriculture waste materials used in this investigation can be constructively used as partial replacement of CSD fillers in the hot mix asphalt binder course. Overall, it is established that MCA is a viable agriculture waste product that can be used as filler materials at a specified percentage in the production of asphaltic binder courses for heavy-trafficked roads. [ABSTRACT FROM AUTHOR]

Cold-mixed epoxy asphalt (CEA) is an emerging energy-saving and environment-friendly material for steel bridge decks, overload roads, and airfield pavement. Occasionally, CEA suffers from impact with high strain rates, which will be extremely detrimental to the pavement's safety and stability. Since little research deals with this dynamic mechanical behavior, this study aims to clarify the dynamic mechanical performance of CEA mixtures (CEAM) under high strain rates. First, this study evaluated the quasi-static strength evolution by Marshall stability tests. The Marshall stability of CEAM more than quadrupled within the first 20 h and 1.6 times up again when exposed at 60°C, while its flow value showed the opposite trend. Then, the dynamic mechanical behavior under different high strain rates and temperatures was investigated by split Hopkinson pressure bar tests. Results showed that the peak strain rate (146–316 s−1) was 1.7–2.0 times greater than the average strain rate (84–162 s−1). The strain–stress curves became steep as the temperature and the pressure ascended. Under the same test conditions, the peak stress and the peak dynamic modulus of CEAM were 1.7 times larger than that of cement concrete. CEAM absorbed more energy below 25°C than 60°C. All the CEAM had binder failure, and the crushed specimens had aggregates broken. The constitutive model of CEAM was established based on the statistical damage theory and the modified Weibull distribution function. Besides, multiparametric regression analysis proved a demarcation point during the impact. [ABSTRACT FROM AUTHOR]

Chloride-based deicing salts are considered to be cost-effective and highly efficient in ensuring safe and efficient roadway and/or aircraft operation during snowy pavement conditions. However, it brings inevitable detrimental effects on the asphalt pavement. This study seeks to elucidate the influence of deicing salt type, concentration, and exposed environment on moisture susceptibility of an asphalt mixture. Immersion Marshall stability testing and freezing-thawing splitting tensile testing were employed to evaluate the moisture susceptibility of the asphalt mixture under drying-wetting and freezing-thawing cycling. Two types of compound deicing agents and three concentrations of 3%, 10%, and 20% of each salt were used to examine and compare their degrees of deterioration on the asphalt mixture. Statistical analysis was performed to establish the relationship between key indicators of moisture susceptibility and the main factors of the asphalt mixture. Microstructure analysis was carried out to elucidate the effects of those factors on the moisture susceptibility of the asphalt mixture using x-ray diffraction (XRD) analysis and scanning electron microscope (SEM) observation. Test results indicated that the moisture susceptibility of the asphalt mixture was greatly influenced by the salt concentration and conditioned drying-wetting (D/W) or freezing-thawing (F/T) cycles. With the increase of D/W or F/T cycles, the Marshall stability, Marshall modulus, and splitting tensile strength decreased while the flow value increased. The 3% salt concentration showed a significant effect on moisture susceptibility, followed by 10% and then 20%. The proposed models can effectively predict the key indicators of moisture susceptibility with high correlation coefficients over 0.9. As confirmed by the microstructural analyses, the deterioration of the asphalt mixture under simulated environmental conditions was attributed to decreased asphalt-aggregate adhesion from water ingress, salt crystallization, and/or ice formation pressure. [ABSTRACT FROM AUTHOR]

In this study, asphalt binders were modified with polymeric triethylene glycol-based polyboron (PTEGB) and organic-based magnesium oxide (OBMO) at different concentrations. The materials used as additives were synthesized under our laboratory conditions. All modified and unmodified binders were aged by Thin Film Oven Test. (TFOT). The modified and unmodified asphalt binders firstly were evaluated by viscosity aging index obtained from a rotational viscometer. Then, all aged binders were subjected to Fourier transform infrared spectroscopy for obtaining the degree of oxidation. Also, the physical properties of the PTEGB and the OBMO-modified asphalt binders were detected through traditional tests. Marshall stability test was also applied to all aged and non-aged asphalt mixtures to understand mechanical performance and aging effects of the additives on asphalt mixtures. As a result, the optimum PTEGB percentage has been obtained as 2% (w/w), and the optimum OBMO percentage has been obtained as 1% (w/w) according to the aging indexes. The PTEGB and the OBMO additives decreased the TFOT aging of asphalts by 56.7% and 50.6%, respectively. It was also found out that the Marshall stability value of the hot mix asphalt decreased by 23% with the TFOT aging of the original asphalt binder. However, the same value was found as 7% at the OBMO-modified asphalt binder and 8.8% at the PTEGB-modified asphalt binder. [ABSTRACT FROM AUTHOR]

The usage of polymer-modified asphalt binders has increased as a result of the significant increase in the number of conventional cars operating on Iraqi roads in recent years. This has resulted in increased strains being placed on pavement structures and materials. Global exploration has focused on the development of stabilizing Stone Mastic Asphalt mixtures for improved pavement behavior. Numerous effective efforts were made to stabilize stone mastic asphalt mixes with polymers and fibers. Iraq produces a considerable amount of waste polymer materials each year. Usually, they are sent to landfills for disposal. These wastes are dumped, occupying a sizable portion of landfill space and creating various serious environmental issues. The study focuses on how waste polymer additions, such as recycled plastic bottles, shopping boxes, and tire crumb rubber, affect the mechanical performance and durability of stone mastic asphalt mixtures. The mechanical performance attributes were assessed. It is evident from the findings that the drain-down amounts were within the permissible requirement range. The findings also showed that the indirect tensile strength, Marshall Stability, moisture damage resistance, and resistance for permanent deformation of stone mastic asphalt mixtures have all increased as a result of the use of waste polymer components. The recycled polymer-modified mixes are the combinations that are most resistant to rutting, according to the results of the repeated load axial creep tests. Iraq may have new options to employ the significant volumes of recycled polymers that are becoming accessible as a result of recycling waste polymers.