Voids In Aggregate Research Articles

Functional and structural assessment of an experimental section gap graded modified with sugarcane bagasse ash

Gap-graded aggregate combined with asphalt rubber presents a high-performance alternative for roads with heavy traffic loads, offering advantages over conventional mixtures in terms of permanent deformation (rutting), fatigue life, and texture. In this study, the conventional filler in the well-established mixture was substituted with sugarcane bagasse bottom ash (SCBA) at a proportion of 5% of the total mineral aggregates. The objective was to enhance the mechanical performance of the asphalt coating while ensuring proper disposal of this waste material. Compared to conventional filler, SCBA is less dense, has smaller dimensions, and exhibits greater roughness, thereby affecting the volumetric parameters of the Marshall mix design. Consequently, the volume of voids in mineral aggregates and voids filled with asphalt increased while maintaining the same volume of air voids (5.3%). Consequently, there was a notable increase in Marshall Stability (40%) and Indirect Tensile Test (22%) mechanical parameters. Following laboratory analysis, the modified mixtures were applied as asphalt coating on a high-traffic highway (BR-158). Field specimens revealed an 18% increase in the Resilience Modulus (4088 MPa; 3478 MPa). Additionally, its Flow Number exhibited a 73% increase (16,707; 9681), and its permanent deformation rate was 28% lower within 10,000 cycles in the dynamic creep test. This was further supported by an 11% reduction in permanent deformation rate in the Hamburg Wheel Tracking Device (HWTD) within 20,000 cycles (3.2 mm; 3.6 mm). In conclusion, the partial replacement of conventional filler with sugarcane bagasse ash within the established granulometric range has demonstrated technical feasibility both in laboratory and field settings.

Analisis Pengaruh Serbuk Besi Sebagai Substitusi Agregat Halus pada Lataston Lapis Aus (HRS-WC) Terhadap Kinerja Jalan Beraspal

Damage to flexible pavements is still commonly found in Indonesia. As technology develops, there is some research regarding using iron powder as an alternative replacement material for asphalt mixtures. This research used iron powder waste as a substitute for fine aggregate in Hot Rolled Sheet–Wearing Course with levels of 0%,15%,30%, and 45%. The purpose of this research to determine the Optimum Asphalt Content (OAC) and optimum percentage of iron powder waste addition as a substitute for fine aggregate to the indicator of Marshall test based on The General Specification of Bina Marga 2018 (Revision 2). Based on Marshall testing that has been carried out, the OAC values are 7,5% with an average of stability 2040,46 kg, flow 3,40 mm, MQ 600,24 kg/mm, voids in mix 4,69%, voids in mineral aggregate 18,30%, and voids filled with asphalt 74,39%. While the optimum percentage of iron powder value is 13% with an average of stability 2091,90 kg, flow 3,17 mm, MQ 662,79 kg/mm, voids in mix 3,92%, voids in mineral aggregate 17,59%, and voids filled with asphalt 77,72%. The result met the General Specification of Bina Marga 2018 (Revision 2). The addition of iron powder as a substitute for fine aggregate in HRS-WC is can increase stability but reduce air voids in the asphalt mixture. This result makes the asphalt mixture more impermeable and plastic.

Effect of High Polymer, Crumb Rubber, and Epoxy-Modified Asphalt Binders on Laboratory Performance of Open-Graded Friction Course Mixtures

Open-graded friction course (OGFC) is a thin asphalt mixture surface layer. It is gap-graded with a high percentage of coarse aggregates that are nearly uniform in size, resulting in a high percentage of interconnected air voids and asphalt binder, which provides improved skid resistance, visibility, and decreased pavement–tire noise. However, construction personnel at the Louisiana Department of Transportation and Development reported that conventional OGFC mixtures have durability issues and shorter service life, compared with thin asphalt mixture lifts. Hence, effects of different asphalt binder types on the performance of OGFC mixtures were evaluated. Five types of asphalt binder were utilized: conventional styrene-butadiene-styrene (SBS) asphalt binder PG 76-22M; high SBS content asphalt binder PG 88-28; diluted epoxy asphalt (EA) binder with two different dosages (25% and 50%); and a hybrid modified asphalt binder prepared with SBS and crumb rubber modifier PG 76-22G. The optimal aggregate structures were determined based on minimum required air voids and voids in coarse aggregate. Physical and mechanical tests were conducted to assess the performance of OGFC mixtures, including draindown, permeability, loaded wheel track, and Cantabro abrasion loss. Results indicate that OGFC mixtures incorporating diluted EA binder exhibited lower draindown values than mixtures containing PG 76-22M and PG 88-28. Moreover, mixtures with PG 88-28 and 50% EA binders demonstrated improved resistance to rutting. Mixtures with 50% EA and PG 88-28 binders demonstrated improved durability, compared with mixtures with PG 76-22M for unaged and aged conditioning, as measured by Cantabro abrasion loss values.

Evaluating the influence of volumetric properties on back-calculated asphalt layer moduli using falling weight deflectometer data

The back-calculation process performed in pavement systems is the numerical analysis of captured deflections to estimate layer stiffness parameters. Prediction of fatigue performance in terms of back-calculated asphalt layer moduli by using a Falling Weight Deflectometer (FWD) has specific challenges in terms of testing protocol, skillset, and complex back-calculation analysis. The performance of the asphalt layer is primarily governed by extrinsic parameters such as temperature, vehicular transient loading characteristics, moisture content, and intrinsic parameters such as binder properties and aggregate mix properties. The role of volumetric properties of asphalt mixes contributes significantly to the back-calculated asphalt layer moduli in terms of the overall life of the structure. The asphalt layer moduli value is dependent on the traditional volumetric properties of asphalt mixes such as air voids in the mix, voids in mineral aggregate, and the percentage of bitumen mix. In this study, a total of 60 in-service pavement sections are identified from three different categories of roads to perform FWD tests and collection of asphalt layer core samples. A detailed laboratory investigation has been carried out to estimate the volumetric properties of different core samples. This study uses field investigations to determine the degree of interdependency between the volumetric characteristics of asphalt mixtures and temperature on the back-calculated layer moduli. Furthermore, the findings from this study are utilized to establish several correlations at the aggregate level, demonstrating strong relationships with R2 values ranging from 0.84 to 0.875. The developed model is validated and depicted in good agreement with the actual values.

Optimizing asphalt mix design through predicting volumetric properties using interpretable machine learning

Traditional asphalt mix design methods primarily rely on experience, consuming immense time and resources. Currently, advanced machine learning (ML) method can accelerate the asphalt mix design procedure. However, historical data on asphalt mix design exhibit high variability, and the outputs of ML models are often challenging to interpret. To address these issues, this study selectively utilized outlier detection algorithms for data preprocessing and employed interpretable ML to predict and explain the volumetric properties of the mixtures, achieving an automated and rapid mix design method. A database (1525 sets of data) of volumetric properties was established based on experimental data of the engineering site. Z-score, KDE (kernel density estimation) and LOF (local outlier factor) methods were employed to detect outliers of the database. Three ML models were trained to predict the volumetric properties of mixture (air void and voids in mineral aggregate), based on material proportion, gradation morphological and material performance features. The SHAP method was used to interpret the extreme gradient boosting (XGB) model, quantifying feature importance, and aiding in decision-making. Finally, an asphalt mix design framework was proposed. The results indicate that the combination of KDE and LOF methods for outlier detection enabled the machine learning model to achieve optimal performance. The XGB model had the best prediction effect on volumetric properties. According to the SHAP method results, the influence of the critical features on the results was explained by the physical laws. The method proposed effectively reducing the design time and costs. The feasibility of the proposed design method was proved by the case study.

Enhancing asphalt mixture performance through waste plastic modification: a comprehensive analysis of optimal compositions and volumetric properties

ABSTRACT This study explores the innovative use of waste plastic, including polyethylene terephthalate (PET), high-density polyethylene (HDPE), and polyvinyl chloride (PVC), as additives in VG30-grade bitumen for road construction. The research focuses on precise proportions of plastics to achieve optimal performance, utilizing a meticulous methodology involving laboratory tests, particularly the Marshall Stability (MS) test. The investigation reveals that a 3.0 % waste plastic content, specifically with 100% PET, and 5.5 % bitumen content results in the highest MS, demonstrating a 73.07 % improvement over the control mix. Additionally, the study examines the nuanced relationships between waste plastic incorporation, bitumen content, and volumetric properties such as air voids, bitumen volume, voids in mineral aggregate, and asphalt-filled voids. The findings emphasize the importance of carefully balancing these factors to achieve the desired properties in the modified asphalt mix. Notably, the 5.5 % bitumen composition consistently demonstrates superior performance across various parameters. The research contributes valuable insights into the potential enhancements brought about by waste plastic additives, particularly 100 % PET, in asphalt mixtures. The identified optimal compositions enable the development of sustainable and high-performance asphalt materials for road construction, meeting the demand for eco-friendly solutions in infrastructure development.

Machine Learning Modeling Integrating Experimental Analysis for Predicting Compressive Strength of Concrete Containing Different Industrial Byproducts

This study aimed to develop accurate models for estimating the compressive strength (CS) of concrete using a combination of experimental testing and different machine learning (ML) approaches: baseline regression models, boosting model, bagging model, tree-based ensemble models, and average voting regression (VR). The research utilized an extensive experimental dataset with 14 input variables, including cement, limestone powder, fly ash, granulated glass blast furnace slag, silica fume, rice husk ash, marble powder, brick powder, coarse aggregate, fine aggregate, recycled coarse aggregate, water, superplasticizer, and voids in mineral aggregate. To evaluate the performance of each ML model, five metrics were used: mean absolute error (MAE), mean squared error (MSE), root mean squared error (RMSE), coefficient of determination (R2-score), and relative root mean squared error (RRMSE). The comparative analysis revealed that the VR model exhibited the highest effectiveness, displaying a strong correlation between actual and estimated outcomes. The boosting, bagging, and VR models achieved impressive R2-scores in the range of 86.69%–92.43%, with MAE ranging from 3.87 to 4.87, MSE from 21.74 to 38.37, RMSE from 4.66 to 4.87, and RRMSE between 8% and 11%. Particularly, the VR model outperformed all other models with the highest R2-score (92.43%) and the lowest error rate. The developed models demonstrated excellent generalization and prediction capabilities, providing valuable tools for practitioners, researchers, and designers to efficiently evaluate the CS of concrete. By mitigating environmental vulnerabilities and associated impacts, this research can significantly contribute to enhancing the quality and sustainability of concrete construction practices.

Performance evolution of novel palm leaf powder used for enhancing hot mix asphalt

Abstract Recently, researchers have been moving toward using local waste as an alternative for construction materials. Using these wastes to pave roads is one of the essential recycling methods, which aims to reduce the consumption of natural resources and environmental pollution resulting from the difficulty of decomposing these wastes. In the Middle East, especially in Iraq, Date Palm fiber is widely available as a local waste material. The aim of this research is to evaluate the performance of a developed asphalt mixture with palm leaf powder (PLP) as a partially substituted mineral filler. The Marshall mix design method produced the asphaltic mixes with ordinary Portland cement and PLP as mineral fillers. PLP was included in three rates denoted by 10, 20, and 30% by the weight of the mineral filler. Marshal stability, flow, bulk specific gravity, air voids, voids in mineral aggregates, voids filled with the binder, the indirect tensile strength, and the indirect tensile strength ratio of the PLP mixture were measured and compared with those of the conventional asphalt mixture. Based on the findings of this study, 20% of the Portland cement could be replaced with PLP, at which all of the properties of the enhanced mixture met the requirements of the Iraqi specifications. Then, the asphalt mix with 20% PLP was tested to assess its resistance against fatigue cracks. The results support the usage of waste PLP in pavement construction, enhancing its properties, which would also be very effective as an eco-friendly material.

Evaluation of the engineering properties of asphaltic concrete composite produced from recycled asphalt pavement and polyethylene plastic.

This study investigated the suitability of recycled asphalt pavement and polyethylene wastes as coarse aggregate in asphaltic concrete by evaluating the impact of the use of polyethylene polymer wastes and recycled asphalt pavement composite as aggregates on the physical and mechanical properties of the asphaltic concrete. The physical characteristics of the aggregate and bitumen were determined using relevant parametric tests. Recycled asphalt pavement was used to make asphaltic concrete samples using LDPE at 5%, 10%, 15%, RAP at 5% and HDPE at 5%, 10%, 15%, and a mixture of LDPE + HDPE at 5+5%, 7.5+7.5% and 10+10% RAP at 5% as additives. Marshall Stability test was conducted to assess the mechanical strength of the asphaltic concrete, and the results included information on the aggregate's stability, flow, density, voids filled with bitumen, voids filled with air, and voids in mineral aggregate. In addition, the surface and crystal structure of the aggregates was studied by carrying out a microscopic examination with a Scanning Electron Microscope (SEM) and X-Ray diffraction (XRD). The results obtained from this study demonstrated that RAP, HDPE & LDPE are viable conventional aggregate substitute for asphalt concrete production.

Industrial Waste As Filler And Pamekasan Aggregate In The Mixture Asphalt Concrete - Wearing Course In Terms Of Marshall Characteristics

Utilization of hot mix asphalt in Pamekasan has increased due to the expansion of road networks for construction and maintenance purposes. The commonly used hot asphalt is AC-WC (Asphalt Concrete - Wearing Course), which serves as the hot asphalt layer for the pavement construction. Historically, the production of hot asphalt mix in Pamekasan involved obtaining materials from outside the Madura region, leading to high production costs. In response to this issue, there is a need for innovation in the composition of hot asphalt mix materials to enhance cost efficiency, especially considering the abundant quantity of materials available in Pamekasan. An innovative approach includes using crushed stone from Pamekasan as an aggregate in hot asphalt mix and incorporating waste materials such as Batumarmar limestone powder and fly ash as fillers. The utilization of local materials from Pamekasan and waste is expected to reduce production costs. For this purpose, 45 samples were created with different percentages, and the Marshall test method was employed to determine values such as density, flow, VMA (voids in mineral aggregate), VIM (voids in mineral aggregate filled with asphalt), VFA (voids filled with asphalt), and stability. Based on the test results, the Optimum Asphalt Content (OAC) was found in a mixture with 4% filler variation and 6% asphalt, yielding a density of 2.287, stability of 917 kg, flow of 3.467 mm, Marshall Quotient of 250.09 kg/mm, VIM of 3.67%, VMA of 15.18%, and VFB (voids filled with bitumen) of 77.68%. Another optimum mixture was identified with a 6.1% asphalt and 10% filler variation, resulting in a density of 2.280, stability of 1,127 kg, flow of 4.50 mm, Marshall Quotient of 250.45 kg/mm, VIM of 3.66%, VMA of 15.16%, and VFB of 76.70%. Additionally, a 6.2% asphalt and 10% filler variation produced a density of 2.285, stability of 1,061 kg, flow of 4.00 mm, Marshall Quotient of 365.28 kg/mm, VIM of 3.31%, VMA of 15.64%, and VFB of 78.84%.

Sound Absorption and Material Properties of Asphalt Rubber Concrete Specimens

The acoustic and material properties of asphalt crumb rubber (ARC) pavement have been measured and correlated. Laboratory measurements revealed nonlinear relationships between the sound absorption coefficients and material properties of compacted specimens as a function of the percentage of crumb rubber content in conventional and modified binders. The acoustic performance of conventional asphalt and asphalt rubber concrete specimens are compared to their material properties as a function of crumb rubber content to determine how crumb rubber content influences sound absorption. The normal incidence sound absorption coefficients, porosity, percentage of voids in mineral aggregate, and absolute gas permeability are measured for specimens containing 0, 5, 10, 15, and 20% crumb rubber in the asphalt binder. The random incidence sound absorption coefficient and material property data share nonlinear distributions within some frequency ranges, as a function of crumb rubber content in the conventional and modified asphalt binders.

The possibility of reusing recycled aggregates in the production of hot mix asphalt

The use of aggregates resulting from destroying concrete as a substitute for natural aggregates in the production of hot mix asphalt for roads with high traffic loads reduces natural consumption and the amount of scattered waste. The study was conducted by designing the hot mix asphalt using the Marshall method with different proportions of recycled aggregate. The results showed an improvement in the stability, flow and indirect tensile tests of the aggregate compared to the conventional mixture. An increase in the recycle aggregate leads to an increase in the proportion of air voids, but it also leads to a decrease in the proportion of voids in the aggregate and asphalt-filled voids. The optimum bitumen content increases with the amount of recycled concrete. Recycled aggregate can be used as a substitute for natural aggregate in hot mix asphalt design successfully. The study found that increasing the percentage of recycled concrete (RCA) in hot bituminous mixtures led to an increase in air voids (VA) and a decrease in voids in mineral aggregates (VMA) and voids filled with asphalt (VFA). However, these percentages decreased with the increase in RCA due to the behavior of the recycled aggregates under load. The optimum bitumen content (OBC) also increased with the increase in RCA. The asphalt mixture's resistance to tensile stress increased with the increase in RCA up to 50% and at 25˚C and RCA 40˚C by up to 8%. The process of using recycled aggregates as an alternative to natural aggregates in hot bituminous mixtures is applicable up to a certain percentage.

Investigating the Effect of Experimental Factors on the Performance of Warm Mix Asphalt with Wax Additive using Application of the Taguchi Method

The objective of this study was to assess the impact of experimental factors on the volumetric properties and performance of warm mix asphalt (WMA) with RH-WMA using the Taguchi method. The gradations of the mixtures were based on AC 14, as specified by the Public Works Department of Malaysia. An L16 orthogonal array was employed to design the mixtures, considering three factors: compaction temperatures ranging from 95 to 140°C, RH-WMA contents ranging from 1% to 4%, and asphalt contents ranging from 3.5% to 6.5%. Sixteen mixtures were prepared according to the L16 array. The study focused on investigating several volumetric properties, including bulk-specific gravity, air voids, voids filled with asphalt, and voids in mineral aggregates. Additionally, the strength behavior of the samples was analyzed using the Taguchi method. The resilient modulus and performance of the mixtures were also evaluated. The results of the study indicate that a high RH-WMA content led to a slight decrease in the strength of the asphalt mixture and air voids. However, it increased the voids filled with asphalt (VFA) and resulted in softening of the asphalt mixtures.

Comparative Assessment of Liquid Antistripping Agents and Mineral Admixtures in Asphalt Mix Resistance to Moisture Damage

The main aim of this research was to investigate the effectiveness of liquid antistrips (LASs) as compared with mineral admixtures such as lime and cement in treating moisture sensitivity of asphalt concrete (AC) mixtures produced with aggregates that are severely susceptible to moisture damage. The study involved evaluating the moisture susceptibility of four mix designs that featured two aggregate sources, two asphalt binder types, and both cement and lime as mineral admixtures. Five different liquid antistripping additives were evaluated. Liquid antistrips were directly added to the binder, and the mineral admixtures in the mix were replaced with mineral filler. The experimental plan involved a volumetric assessment of the mixtures after the filler adjustment and baseline characterization of aggregates and mixtures used in the study. A multipoint moisture sensitivity assessment protocol with a moisture conditioning procedure that includes multiple freeze-thaw cycles was used. Moisture susceptibility was evaluated using a fracture experiment and its parameters in addition to the standard indirect tensile strength. The replacement of both mineral admixtures led to a considerable increase in the air voids and the voids in mineral aggregates for all four mixes. Cement and lime were shown to be effective in retaining strength and fracture energy after several conditioning cycles. The performance of the mixtures containing liquid antistrips showed sensitivity to the additive used. While one of the additives showed overall significant deterioration in strength and fracture energy after the first freeze-thaw cycle, a different additive retained 70% of its initial properties after up to three freeze-thaw cycles. Overall, it was shown that a compatible LAS can aid asphalt mixtures’ moisture resistance but not to the same efficiency of lime or cement for the mixtures included in the study.

Pavement performance of previous pavement materials based on CAVF design

Based on the coarse aggregate void filling method (CAVF), four kinds of permeable asphalt mixtures (PAC) with target voids of 18%, 20%, 22%, and 25% respectively were designed, and their road performance was comprehensively evaluated by a series of laboratory tests, such as permeability tests, immersion Marshalls, freeze-thaw splitting, rutting, low-temperature bending, four-point fatigue bending, and so on. The experimental results show that the CAVF method is more accurate and PAC designed by the CAVF method has more connected voids and better pavement performance. The optimal design void ratio of the PAC is 22%.

Study on the micromechanical response during permanent deformation of asphalt mixtures by discrete element modeling with real aggregate morphology

This study developed a novel 2D virtual rutting model to analyze the permanent deformation mechanism and the micromechanical response of asphalt mixtures. Digital samples of asphalt mixture were image-processed by Python-based algorithms to effectively segment coarse aggregate and asphalt mastic. The Python processed images were imported into PFC2D to establish a 2D virtual rutting model that incorporated the aggregate morphology, the aggregate gradation, and the aggregate void distribution. The feasibility and accuracy of the 2D virtual rutting model were validated by macroscopic laboratory rutting tests. The 2D virtual rutting test had 6.22% higher dynamic stability and 2.12% lower rutting deformation than the laboratory indoor rutting test. As rutting depth increased, the number of effective contacts declined to a steady value. The average Burger contact force between particles within the rutting model increased as loaded. Results demonstrated that the 2D virtual rutting test model was capable of simulating the time-dependent rutting deformation by incorporating Python-coupled algorithms to process aggregates' topography characteristics.

Influence of rice husk ash on moisture susceptibility of warm mix asphalt using chemical based additive

Warm mix Asphalt (WMA) is produced at lower temperatures as compared to hot mix asphalt (HMA). It uses several techniques that influence the viscosity property of the bitumen binder, enhances the workability and is beneficial to produce mixes at lower mixing temperatures. In the present study, the chemical-based additive namely Zycotherm used to produce WMA. The effect of rice husk ash (RHA) which is an agricultural waste was varied from 0 to 100% for the replacements of the filler material. A huge amount of RHA is produced every year in the country and disposal is a big issue. Further, hydrated lime was added to check the ability for moisture resistance as an antistripping agent. The viscosity grade (VG 30) was used as the primary binding agent to the mix. The siliceous type of aggregate was used in the warm mix preparation. Dense Bituminous Macadam (DBM) of grade 2 was adopted as an aggregate gradation from the Ministry of Road Transport and Highways (MoRTH, 2013). The Marshall Stability (MS), Retained Marshall Stability (RMS), volumetric properties such as (air voids, voids in mineral aggregates and voids filled with bitumen), Marshall Quotient (MQ) and Indirect Tensile Strength (ITS) test were used to check the strength performance. The durability was assessed by evaluating refusal density and the tensile strength ratio value as per AASHTO T 283. The results reported that the usage of RHA has shown significant improvement as compared to the control mix. The optimum content of RHA was found to be at 50% replacement of natural stone dust. Further increase in RHA content leads to a decrease in stability value. This might be due to the excess content of RHA absorbing more bitumen and insufficient bitumen has remained for coating the aggregate particles.

Analisis Sifat Dan Karakteristik Campuran Hangat Aspal Emulsi Dengan Variasi Perendaman

The purpose of this study was to analyze the properties and characteristics of the warm mixture of emulsified asphalt and to analyze the effectiveness of the characteristics of the warm mixture of emulsified asphalt with variations of immersion. The independent variable in this study is the immersion variation. The test method refers to the General Specifications of Highways 2018. The type of mixture used is Asphalt Concrete - Wearing Coarse. The performance was measured by testing Density, Stability, Flow, Marshall Quontient, voids in mixture (VIM), voids filled with asphalt (VFB), and voids in aggregate (VMA). The asphalt content used was 6.5%, then repeated immersion was carried out with variations of 3 days, 7 days, and 14 days of immersion. The results showed that the use of a warm mixture of emulsified asphalt and the length of immersion time affected the decrease in the value of the asphalt mixture properties. This is because the longer the immersion the asphalt adhesion to the mixture will decrease and the chance of losing the durability or durability of the mixture is also getting bigger. And from the results of the Marshall test using a warm mixture of asphalt emulsion, the best value for the characteristics is 3 days of immersion. Because it has a higher stability value so it will be able to withstand a greater load

Impact of curing on the volumetric and mechanical properties of cold bitumen emulsion mix

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.

Optimization of asphalt mixture design based on the compressible packing model

Traditional design methods seldom consider accumulation properties, which influence the structure of asphalt mixtures. Therefore, this study is the first to put forward a modified compressible packing model. The filling characteristics of coarse aggregate were studied. Different matrix compaction indexes η and compaction indexes K were selected to study the influence of the modified compressible model on pavement performance. Design methods based on a 4% air void and minimum voids in mineral aggregate were compared through the volumetric parameters and pavement performance based on the modified compressible packing model. The asphalt mixture performances with three gradations were analyzed. The test results showed that as the matrix compaction index η decreased, the optimum asphalt content of both methods increased, while the VMA decreased. Finally, an optimized asphalt mixture design method based on the compressible packing model was proposed, which showed good prospects for application.