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Flexible pavements stand out as the most commonly used worldwide, compared to rigid and composite pavements, owing to their versatility and widespread application. The use of hot mix asphalt (HMA) in flexible pavements causes significant environmental concerns due to high CO2 emissions and energy consumption, whereas warm mix asphalt (WMA) technologies have gained popularity in recent decades, offering a more sustainable alternative by enabling asphalt production at lower temperatures. WMA technologies can be categorized into three main groups: foaming, organic additives, and chemical additives, with each offering distinct benefits for performance and environmental impact. One of the chemical additives used in WMA production is Cecabase RT BIO10. In this study, virgin bitumen with 50/70 penetration was modified by adding Cecabase RT BIO10 at four levels: 0%, 0.3%, 0.4%, and 0.5% by weight. The experimental design employed a Taguchi L16 orthogonal array to systematically evaluate the effects of various factors on modified bitumen performance. Binders were prepared at four temperatures (110 °C, 120 °C, 130 °C, and 140 °C), four mixing durations (15, 20, 25, and 30 min), and four mixing speeds (1000, 2000, 3000, and 4000 rpm), enabling an efficient analysis of each parameter's impact. The prepared binders were subjected to a series of tests, including penetration, softening point, flash point, rotational thin film oven test (RTFOT), elastic recovery, Marshall stability, ultrasonic pulse velocity (UPV), and FTIR analysis. These tests were conducted to investigate the effects of various parameters and levels on the binder properties. Additionally, stiffness and seismic modules were evaluated to provide a more comprehensive understanding of the binder's performance. The experiment results revealed that the penetration, elastic recovery percentage, and Marshall stability increased with increasing additive content while the softening point and RTFOT mass loss decreased. At a high service temperature of 40 °C, the stiffness modulus of the modified bitumen decreased slightly. At a low service temperature of −10 °C, it decreased further. Additionally, the incorporation of Cecabase RT BIO10 led to an increase in the seismic modulus. Through optimization using the Taguchi method, the optimal levels were determined to be a 0.4% Cecabase RT BIO10 ratio, 140 °C mixing temperature, 30 min mixing time, and 1000 RPM mixing speed. The optimal responses for each test were identified and integrated into a unified optimal response, resulting in a comprehensive design guide with 95% confidence level estimates for all possible level combinations. [ABSTRACT FROM AUTHOR]

A significant amount of reclaimed asphalt pavement must be used to address the growing demand for sustainable road-building materials. One of the problems of employing RAP in mixes is that it makes them more rigid. The guideline specifies that when the amount of RAP is greater than 15%, softer-grade asphalt should be used; however, the asphalt used in Baghdad is 40–50 grade, and its high viscosity makes it challenging to mix when adding RAP. Sometimes, softer grades are not readily available and must be made upon request. Therefore, using some waste oil as a rejuvenator was the task. It is more economical and environmentally friendly. In this study, three asphalt grades (40-50, 60-70, and 85-100) are used, and three distinct types of fillers; hydrated lime, Portland cement, and limestone dust; with an aggregate gradation of maximum size (12.5 mm). Three percentages of recycled asphalt pavement (RAP) materials, 10%, 20%, and 30%, are used. Based on Marshal graphs, the optimum asphalt cement content for each grade was calculated. The samples in all blends were subjected to volumetric analysis, Marshall Stability, flow, and water sensitivity testing. The findings of this study showed that adding hydrated lime enhanced Marshall properties and reduced the sensitivity of asphalt mixes to moisture. Stability increases as the proportion of RAP increases. Asphalt (40-50) with 4% waste oil showed improved stability than the original asphalt mix and presented better Marshall properties than the softer grade (85-100). Additionally, mixes containing RAP may be less moisture-resistant than conventional mixtures.

The main material used in the construction of roads is asphalt. Therefore, the recognition of asphalt's mechanical aspects is very important. One of the important features of asphalt is its shear strength, which should be measured accurately. However, the methods that have been presented to measure this important factor of asphalt always encounter weaknesses. So, it is necessary to find a suitable method to determine the shear strength of asphalt with more accurate results and high compatibility with reality. In this regard, the purpose of the present research was to design jaws in order to measure the shear strength in the direction and opposite direction of the traffic path and provide a model to predict shear strength using Marshall stability resulting from invented jaws. In order to examine the accuracy of the designed jaw in this study, two different types of asphalt, Binder 0–25 and Topeka 0–19 grading, were used. For this purpose, Marshall stability and shear strength tests in the direction and opposite direction of the Marshall were conducted with 12 repetitions on these samples. Also, the genetic programming (GP) evolutionary algorithm was applied in this study to provide a prediction model of shear strength. The results of this study indicated that there was a significant relationship between the Marshall stability and the shear strength in the direction and opposite direction of the Marshall applying the invented jaws in both asphalt types, and the coefficient of determination (R2) for the Binder and Topeka were 0.93 and 0.97 in the Marshall's direction and 0.96 and 0.95 for the Marshall's opposite direction, respectively. Also, the results of the GP method indicated that the relationships between predicted and actual values of shear strength for Binder and Topeka asphalt types were appropriately described by R2 of 99.47% and 99.21% with RMSE of 8.0177 and 5.0143 in the traffic direction, and R2 of 97.45% and 98.08% with RMSE of 1.2684 and 0.7035 in the traffic opposite direction, respectively. Therefore, GP provided a more suitable fit of all experimental data for both Binder and Topeka asphalts, and it can be said that with the help of new designed jaws, the shear strength in the direction and opposite direction of the Marshall can be estimated with high accuracy. [ABSTRACT FROM AUTHOR]

Industries produce large amounts of electric induction furnace steel slag (EIF) and copper slag (CuS) as waste, and their disposal poses serious economic and environmental issues. The use of these slags in pavement could ease environmental concerns and promote the conservation of non-renewable resources. This paper is based on an experimental investigation into the potential for employing EIF and CuS at 0, 5, 10, 15, 20, and 25% as a partial replacement of fine Natural Granite Aggregate (NGA), whose size ranges from 4.75 mm to 0.075 mm, in producing dense Hot Mix Asphalt (HMA) mixes. The physical, chemical, morphological, and expansive properties of EIF and CuS were investigated. The Marshall method of mix design was adopted to produce HMA mixes. The results showed that for EIF-based HMA mixes, stability, Indirect Tensile Strength (ITS), and rutting resistance increased, whereas for CuS-based HMA mixes, these properties decreased but satisfied their required permissible criteria. The Tensile Strength Ratio (TSR) of EIF and CuS-based HMA mixes was found to be increased. The findings of this study indicated a high possibility for using EIF and CuS as aggregates, and a replacement level of 20% of these slags in HMA mixes was suggested as optimal. [ABSTRACT FROM AUTHOR]

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]

The asphalt pavements in Pakistan suffer from various failures where rutting and fatigue cracking are significant. These failures may occur due to uncertainty in predicting actual traffic, material properties, poor construction methods, and poor mix design. As per existing literature, polypropylene fibers (PPF) have been extensively used in pavement engineering for many years to cope with the pavement failures. These PPF are effectively used in asphalt concrete due to the adequate adhesion between PPF, bitumen, and aggregate. Therefore, in the current study, the asphalt concrete specimens for Marshall Stability, Rut resistance, and Moisture damage, modified with PPF, ranging from 2% to 10% by weight of optimum binder content (OBC), were produced at a mixing temperature of 160o C and tested as per ASTM D1559, ASTM D8292, and ASTM D6931 protocols, respectively. An OBC of 4.42% by weight of the Marshall specimen for the conventional mix was concluded in terms of Marshall Stability and flow. The PPF of 8%, by weight of OBC, used as per the wet method in the asphalt mixture, was concluded to be optimum in terms of Marshall Stability of 15.2 KN and flow value of 2.2 mm. The modified asphalt mixtures at PPF content of 8% leads to a least rut depth of 3.44 mm as compared to conventional specimens having rut depth of 7.35 mm, particularly due to the PPF's long-lasting integrity formed in the modified asphalt mixture at an 8% PPF content, supporting the asphalt mixture's ability to sustain repeated wheel loads. The values of TSR showed an increasing trend with the increase in PPF content from 2% to 8%, particularly due to the adequate mobility and dispersion of the PPF in the asphalt mixture and cohesion due to the optimum coating in the asphalt mixture. The TSR value of the asphalt mixture decreased at 10% PPF content as compared to conventional asphalt mixtures because of excessive rigidity or a lack of the required marginal flexibility in the asphalt mixture because of excessive PPF content. Therefore, the asphalt mixture modified with 8% PPF fibers as per wet method is recommended to be used in the construction industry to control permanent deformation and moisture damage in asphalt mixtures. [ABSTRACT FROM AUTHOR]

The traditional method for determining the Marshall stability (MS) and Marshall flow (MF) of asphalt pavements is laborious, time consuming, and costly. This study aims to predict these parameters using explainable machine-learning techniques. A comprehensive database comprising 721 hot mix asphalt (HMA) data points was established, including variables such as aggregate percentage, asphalt content, and specific gravity. Models were constructed using the PyCaret Python library, and their performance was assessed using metrics such as the mean absolute error (MAE) and coefficient of determination (R²). The CatBoost regression model outperformed the other models, achieving R² values of 0.835 and 0.845 for MS and MF, respectively. Additionally, Shapley values were used to quantify the variable effects on the predictions. This approach enables the efficient preselection of design variables, reducing the need for extensive laboratory testing and promoting sustainable construction practices.

Flexible pavements stand out as the most commonly used worldwide, compared to rigid and composite pavements, owing to their versatility and widespread application. The use of hot mix asphalt (HMA) in flexible pavements causes significant environmental concerns due to high CO2 emissions and energy consumption, whereas warm mix asphalt (WMA) technologies have gained popularity in recent decades, offering a more sustainable alternative by enabling asphalt production at lower temperatures. WMA technologies can be categorized into three main groups: foaming, organic additives, and chemical additives, with each offering distinct benefits for performance and environmental impact. One of the chemical additives used in WMA production is Cecabase RT BIO10. In this study, virgin bitumen with 50/70 penetration was modified by adding Cecabase RT BIO10 at four levels: 0%, 0.3%, 0.4%, and 0.5% by weight. The experimental design employed a Taguchi L16 orthogonal array to systematically evaluate the effects of various factors on modified bitumen performance. Binders were prepared at four temperatures (110 °C, 120 °C, 130 °C, and 140 °C), four mixing durations (15, 20, 25, and 30 min), and four mixing speeds (1000, 2000, 3000, and 4000 rpm), enabling an efficient analysis of each parameter’s impact. The prepared binders were subjected to a series of tests, including penetration, softening point, flash point, rotational thin film oven test (RTFOT), elastic recovery, Marshall stability, ultrasonic pulse velocity (UPV), and FTIR analysis. These tests were conducted to investigate the effects of various parameters and levels on the binder properties. Additionally, stiffness and seismic modules were evaluated to provide a more comprehensive understanding of the binder’s performance. The experiment results revealed that the penetration, elastic recovery percentage, and Marshall stability increased with increasing additive content while the softening point and RTFOT mass loss decreased. At a high service temperature of 40 °C, the stiffness modulus of the modified bitumen decreased slightly. At a low service temperature of −10 °C, it decreased further. Additionally, the incorporation of Cecabase RT BIO10 led to an increase in the seismic modulus. Through optimization using the Taguchi method, the optimal levels were determined to be a 0.4% Cecabase RT BIO10 ratio, 140 °C mixing temperature, 30 min mixing time, and 1000 RPM mixing speed. The optimal responses for each test were identified and integrated into a unified optimal response, resulting in a comprehensive design guide with 95% confidence level estimates for all possible level combinations.

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]

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]

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]

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]

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 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.

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.

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]

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]