Performance Of Hot Mix Asphalt Research Articles

Evaluating the effect of paper waste lignin in hot mix asphalt

Asphalt is a viscoelastic material which performs to resist rutting, fatigue cracking, and moisture susceptibility under different loading and temperature conditions. The use of innovative and renewable pavement construction materials is inevitable due to high axle loads, rapidly increasing traffic volumes, and varying climatic conditions. This study aims to assess the effect as well as the optimum dosage of paper waste lignin for use in hot mix asphalt (HMA). Lignin from the paper industry with dosage ratios of 5, 10, 15, and 20%, was utilized to study the effect of the addition of lignin to the asphalt binder. Virgin and lignin-modified binder samples, before and after the aging process, were subjected to physical testing through penetration, softening point, ductility, viscosity and specific gravity and rheological characteristics through dynamic shear rheometer (DSR), bending beam rheometer (BBR), and rational viscometer (RV). The fractional composition was assessed through saturates, aromatics, resins and asphaltenes (SARA) fractional composition technique. Statistical analysis was also performed to find correlation of different physical and rheological parameters. Furthermore, based on optimum dosage, the performance of asphalt mixtures was studied against rutting, fatigue cracking, and moisture susceptibility. The results indicated that the addition of lignin has improved the physical properties significantly. The amount of asphaltene decreased and aromatics increased in SARA fractional analysis. Moreover, the Colloidal Instability Index (CII) has also indicated a stable structure of the binder. The rheological characteristics are improved after modification. The asphalt mixture tests revealed that addition of lignin with optimum dosage (10%) has improved the performance against rutting, fatigue cracking and moisture susceptibility. Statistical analysis indicated good co-relation among different physical and rheological parameters. This study concludes that 10% dosage is the optimum dosage that can successfully replace the virgin asphalt binder for performance of hot mix asphalt.

EVALUATION OF LOCUST BEAN POD ASH AS MINERAL FILLER IN HOT MIX ASPHALT

An increase in the consumption of agricultural products generates large quantities of waste daily. The husks of the locust bean seeds when removed from the plant are littered in the environment which negatively affects the environment. In this research, locust bean pod ash (LBPA) was used as a mineral filler in hot mix asphalt. Physical and chemical tests were done on the aggregate, bitumen and LBPA, showing adequacy for use in asphalt concrete production. All tests were conducted in accordance with relevant standards. LBPA was admixed with granite dust from 0–50% (at intervals of 10%) with varying bitumen content from 4–7% (at 0.5% intervals). For this experiment, the Marshall mix design method was used. The Marshall stability of samples containing LBPA improved by 19%, from 8.16kN to 9.67kN. Similarly, Marshall flow decreased by 19% from 3.4 mm to 2.75 mm. The density-void analysis of the asphalt samples also revealed an improvement. The microstructural examination revealed an enhanced structural arrangement due to the flocculation of the LBPA particles. Overall, the hot mix asphalt samples meet the Federal Ministry of Works and Housing specifications for flexible pavement-wearing courses. It was determined by the study that adding 40% LBPA with 60% granite dust at 5% bitumen content would improve the performance of hot mix asphalt.

Effect of specimen size on mode I fracture performance of hot mix asphalt at the low temperature

The size of test specimens plays a significant role in determining the fracture characteristics of asphalt mixtures. Nonetheless, current research exploring how specimen dimensions affect the fracture behavior of asphalt concrete remains somewhat scant. This investigation employed a sequence of laboratory-based semi-circular bending (SCB) tests to examine the effect of specimen diameter on the fracture characteristics of two distinct asphalt mixtures at −10 °C. The study assessed specimens across four varying diameters − 76 mm, 100 mm, 125 mm, and 150 mm - paired with two notch-to-radius ratios of α = 0.2 and 0.4. To assess the fracture resistance, key parameters including the stress intensity factor (KIC), stiffness, and various energy metrics – fracture energy (GF), elastic storage energy (Ue), dissipated energy (Ud), and post-peak energy (Up) - were meticulously measured. Results indicated that for both AC10 and AC16 mixtures, there was a consistent increase in KIC corresponding with larger diameters for all examined notch-to-radius ratios. Additionally, this progressive rise in KIC with increasing diameter demonstrated a decreasing rate of growth, particularly noticeable as diameters approached the 150 mm mark. Maintaining a constant notch-to-radius ratio (α), the fracture energy was observed to increase in step with specimen size. With α fixed at 0.2, enlarging the diameter from 76 mm to 150 mm resulted in considerable gains in fracture energy – 53.7 % for the AC10 mixture and an even more striking 70.5 % for the AC16 mixture. With the increase in specimen size, an initial uptick followed by a subsequent decrease in stiffness was observed. This pattern is attributed to the interplay between the fracture process zone and variations in porosity distribution. The increase in α led to a discernible reduction in the magnitudes of Ue as well as its relative contribution for specimens of equivalent size. Simultaneously, as specimen sizes expanded, there was a consistent climb in the proportion of Ue, usually culminating at a specimen diameter of 125 mm, and then decreased when the specimen diameter continuously increased to 150 mm. Besides, the evolutions of Gf, Ue, and Ud were analyzed to acquire the effects of specimen size and notch-to-radius ratio (α). Statistical analysis showed that specimen size, and notch-to-radius ratio were both significant factors affecting KIC and GF, while mixture type did not emerge as a substantial factor influencing these properties within the scope of this study.

Investigation of the fracture performance of reclaimed asphalt mixture at the intermediate temperature using multi-parameters

Fracture energy (Gf) and J-integral are two widely used parameters to evaluate the intermediate-temperature fracture performance of hot mix asphalt. Other parameters, such as balanced cracking index (BCI), cracking resistance index (CRI), cracking tolerance index (CTindex) and toughness index (TI), were proposed to characterize the fracture performance subtly. However, these parameters generally could not generate consistent fracture performance. In this study, six indices (Gf, J-integral, BCI, CRI, CTindex and TI) were selected to characterize the intermediate-temperature fracture performance of HMA to address the effects of RAP and rejuvenator on the fracture resistance. The overall fracture performance of all mixtures was evaluated using all these parameters using a scoring method. Pairwise correlation analysis was conducted among the variables. In addition, coefficients of variability (COV) were also measured. The results showed that all facture parameters indicated that a certain amount of RAP could enhance the fracture performance. However, the optimal contents of RAP were inconsistent among different fracture parameters. Rejuvenator could improve the fracture resistance. The fracture score of HMA with 50% RAP was highest, indicating the fracture resistance of HMA with 50% RAP was superior considering all the fracture variables. Pairwise correlation analysis showed that Gf presented poor correlations with all other variables. BCI, CTindex and TI showed large COVs, while Gf, J-integral and CRI showed low COVs.

ASPHALT BINDERS EMPLOY VARIOUS ORGANIC ADDITIVES: PHYSICAL AND RHEOLOGICAL QUALITIE

Several studies aim to reduce surface temperatures and improve the performance of hot mix asphalt. These studies have occurred to reduce the global warming phenomena and economic concerns. We're researching how organic materials affect the viscosity of modified asphalt. Asphaltan A, Asphaltan B, Asphaltan C, and T-grade are organic additives. temperatures with the asphalt binder were employed in the current study. These organic additives were used to improve the characteristics of hot-mix asphalt. In addition, it increases the durability, and lifespan of pavement and reduces mixing and compaction temperatures. A penetration grade bitumen of 40/50 was used in this study. Then, pure bitumen was added to the organic additives to modify binders containing varying concentrations of each additive. Physical properties were performance at different levels of additives. In the research, conventional bitumen/asphalt should be adjusted due to climate conditions, strong traffic loads, and growing axial loads. As a result, asphalt mixtures comprehending bitumen with a high penetration index are less prone to low-temperature cracking and irreversible deformation. Traditional asphalt studies found that bitumen samples with the softening point of warm mix asphalt additives were greater rate, and were less susceptible to temperature changes. The introduction of organic compounds increased the penetration and softening point of the asphalt substantially. This indicated that the stiffness and thermal expansion of the binder had gotten better.

Evaluation of the Healing Performance of Hot-Mix Asphalt Containing Waste Steel Shavings under Different Microwave Induction Healing Cycles

Evaluation of the Healing Performance of Hot-Mix Asphalt Containing Waste Steel Shavings under Different Microwave Induction Healing Cycles

Modulus of recycled hot mix asphalt: Micromechanical modeling and experimental approaches

To improve the availability of reclaimed asphalt pavement (RAP) in recycled hot mix asphalt (HMA), this study is focused on the mechanical performance of recycled HMA, which is beneficial for environmental conservation and consistent with the concept of sustainability. To alleviate the heterogeneity of the material composition of recycled HMA and enhance the usability and applicability of research means, micromechanical modeling is used to examine the modulus of recycled HMA, which is a critical parameter for asphalt pavement analysis. In this investigation, a four-layer built-in micromechanical model was constructed and derived to characterize recycled HMA. The micromechanical model indicated that the modulus of recycled asphalt was the main factor influencing the modulus of recycled HMA. Thus, the following study took the modulus of recycled asphalt as the main study subject. The frequency sweep test and three-point flexure beam test for recycled asphalt were designed and conducted to clarify the change trend of influence factors and further verify the reasonability and feasibility of the micromechanical model. Considering the diffusion behavior of the rejuvenator, the change trends of the factors are explored. The curing time apparently influences the modulus of recycled asphalt, followed by the curing temperature and the rejuvenator proportion. Finally, analytical results from micromechanical model matched well with the experimental results. The results of this study may be valuable for predicting the dynamic moduli of recycled HMA.

Pure modes I and II fracture behavior of Modified-Hot mix asphalt (HMA) under Long-Term aging condition

Top-down crack (TDC) as one of the pavement distresses, has a significant contribution to the quality of pavement service. Low-temperature top-down crack, which are subcategories of low-temperature crack (LTC) is representative of the cracks located on the pavement's surface and are directly affected by different environmental conditions such as temperature, air (oxygen), and light. Therefore, in the pavement body, this type of crack is more affected by long-term aging (LTA) than other cracks. To make sustainable mixtures, this research, it was tried to assess the long- and short-term fracture performance of hot mix asphalt (HMA) and HMA reinforced with different percentages of hospital waste pyrolysis carbon black (HWPCB) and hospital waste pyrolysis hydrocarbon (HWPHC) under mode I and II. The symmetrical specimen SCB and modified specimen SCB-2 geometries are utilized to simulate pavement crack behavior under tensile (opening) deformation and shear (sliding) deformations, respectively. For simulating the cracking behavior of semi-circular bending (SCB) samples in the laboratory with the pavement cracking behavior under the LTA process, an LTA condition, which was equivalent to a 12-year failure, was applied. Then, the long- and short-term fracture performance of the samples was examined using different fracture indices at temperatures of −15 °C. The results revealed that adding HWPCB and HWPHC to the HMA sample improved the fracture energy (GIIF and GIF) and fracture toughness (KIIC and KIC) of the HMA mixture under modes II and I (at −15 °C). Also, the improvement of the fracture stiffness and reduction of fracture brittleness of HMA specimens reinforced with HWPCB and HWPHC was concluded in long- and short-term conditions at the studied temperature (under modes II and I). From an operational point of view, the HMA mixtures reinforced with lower percentages of HWPCB and HWPHC are recommended for use in areas with an average temperature of about −15 °C and medium-heavy vehicle volumes. Also, the HMA mixtures reinforced with higher percentages of HWPCB and HWPHC are recommended for use in areas with medium temperatures and medium-heavy vehicle volumes. Moreover, the mixture containing both additives (HWPCB + HWPHC) is recommended for areas with medium temperature and high heavy vehicle volumes.

Investigation on heat transfer mechanism of asphalt pavement in winter transportation: An experimental and numerical study

The asphalt pavement is prone to temperature segregation. Most current studies focus on the temperature variation of hot-mix asphalt (HMA) during the paving stage in normal conditions. However, there is a lack of investigation on the performance of HMA during transportation process in winter. Insulation layers are necessary to prevent the change of HMA property, being equipped on the transportation truck. Field tests are performed on a highway to estimate the feasibility of insulation materials by monitoring the temperature variation of HMA throughout the transportation process. A Multiphysics finite element model is developed in COMSOL. The sensitivity analysis is conducted in terms of the properties of HMA. The insulation layer is effective in impeding heat transfer and keep the temperature of HMA. This improvement is more intense at larger depths. The environmental condition is less influential than the HMA properties. Recommendations are provided to moderate driving routes and locations of the mixing station by determining the worst cooling rate. This study aims to reveal the performance of insulation material and HMA in winter constructions for a typical highway. A theoretical basis is provided to optimize the construction sequences based on the investigation of the heat transfer mechanism.

Influence of Compaction Energy on the Mechanical Performance of Hot Mix Asphalt with a Reclaimed Asphalt Pavement (RAP) and Rejuvenating Additive

Influence of Compaction Energy on the Mechanical Performance of Hot Mix Asphalt with a Reclaimed Asphalt Pavement (RAP) and Rejuvenating Additive

Effect of design parameters on degree of blending and performance of recycled hot-mix asphalt incorporating fine reclaimed asphalt pavement particles

Due to the rich binder content and high economic benefits of fine reclaimed asphalt pavement (RAP) particle, more and more attention has been paid to the effective design of recycled hot-mix asphalt (HMA) incorporating this material. This research explored the effect of design parameters on degree of blending (DoB) and performance of recycled HMAs incorporating fine RAP particles. Six groups of mixes were designed, including one no blending group, four experimental groups, and one full blending group. The different parameters of preheating temperature, compaction effort, asphalt content (AC), and blending duration, were involved in this research. It can be found that the recycled HMAs incorporating fine RAP particles under the traditional design proved to the risks in water stability and low-temperature performance. By rising the preheating temperature, decreasing compaction effort and increasing AC, or extending the blending duration, more RAP binder would be activated and blended with the virgin binder, and the poor rheological performance of recycled HMAs can be restored. The different design parameters have different effects on the performance. Besides, the actual contribution of DoB to performance was quantified. With an increase in DoB by 10%, the tensile strength ratio, shear strength, fracture energy, fracture strength, and abrasion loss percentage of recycled mixes can improve by around 15%∼28%, 0.15–0.34 MPa, 180–1969 J·m2, 0.25–0.34 MPa, and 7–18%, respectively. In addition, design incorporating fine RAP particles generally can bring significant advantages in energy consumption and CO2 emission.

Improving the Performance of Hot Mix Asphalt Using Rock Asphalt as a Fine Aggregate

Improving the Performance of Hot Mix Asphalt Using Rock Asphalt as a Fine Aggregate

Recyclability of reclaimed asphalt rubber pavement

Rubberized asphalt technology has been developed and applied in the production of hot-mix asphalt (HMA) for several years, as it represents a profitable solution to dispose of the waste rubber from end-of-life tires and to improve bitumen rheological and mechanical behaviour. However, the question about the recyclability of reclaimed asphalt rubber pavement (RARP) into new HMA has not been still solved. To this aim, the present study dealt with characterization of HMA including 30% RARP, in comparison with reference mixtures with 30% of ordinary reclaimed asphalt pavement (RAP) and with only virgin materials. The experimental programme included the preliminary analysis of RARP and RAP binders, then the HMA design and testing in terms of strength, stiffness, linear viscoelastic properties and fatigue resistance. The results demonstrated that RARP can be recycled into new mixtures without negatively influencing the overall HMA performance. In particular, the RARP entailed an increase of mix stiffness and brittleness, but with a lower severity with respect to RAP. The use of a rejuvenating agent allowed achieving a mechanical behaviour similar to that of the reference mix with only virgin components.

Stiffening effects of LFS slags reused as filler in asphalt mixtures

Nowadays, the use of Ladle Furnace Steel (LFS) is spreading in the field of asphalt pavements. LFS are generally used as filler in Hot Mix Asphalt (HMA). The main purpose of this study is to analyse and understand the role of LFS characteristics on the possible stiffening effects of asphalt materials. Different characteristics of LFSs, such as particle size distribution, specific surface area (SSA), chemical and mineralogical properties were evaluated in addition to the performance of HMAs on different scales (mastic and HMA). One type of LFS, one standard limestone and their blends were mixed with two different asphalt binders, one pure and one 3.5% Styrene–Butadiene–Styrene (SBS) cross-linked modified. The results showed no significant correlations between the physical properties of the LFS and the performance levels of the HMAs, but it was pointed out that the LFS content in the filler blend should not exceed 30%.

Investigation on Fracture Performance of Hot-Mix Asphalt with Reclaimed Asphalt Pavement under Fatigue Loading

Reclaimed asphalt pavement (RAP) has been widely used in asphalt pavement. However, the fatigue performance of hot-mix asphalt (HMA) with RAP is a critical factor to ensure durability. In this study, fatigue tests using an Overlay Tester (OT) were conducted using a novel load-controlled mode. RAP contents were 0, 25% and 50%, respectively. In the cyclic loading, fatigue life and energy parameters were measured. Results indicated that RAP decreased both the fracture energy and tensile strength. Fatigue life was determined using two methods. RAP was proved to be beneficial in prolonging the fatigue life using the two methods at 25 °C. However, opposite conclusions were made about the effect of RAP on fatigue life at −10 °C. At −10 °C, compared to HMA without RAP, the cumulative dissipated energies decreased by 49.1% and 77.3% when RAP contents were 25% and 50%, respectively. At 25 °C, compared to HMA without RAP, the inclusion of 25% RAP increased the cumulative energy by 31.1%, while 50% RAP decreased the cumulative energy by 41.2%. The developments of the dissipated energy and the cumulative energy were consistent with the fatigue life results determined by the first method.

Appraising the synergistic use of recycled asphalt pavement and recycled concrete aggregate for the production of sustainable asphalt concrete

Material obtained from the demolition of concrete structures and milling of flexible pavements has the highest potential for recyclability. This study aimed to evaluate the performance of hot mix asphalt with the concurrent use of recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA). Contents of RAP and RCA were varied from 0% to 50% by fixing the total recycling materials percentage to 50%. Penetration grade 40/50 virgin binder and waste engine oil (WEO) as rejuvenator were used in the present study. A series of tests, such as Scanning electron microscopy (SEM), Marshall stability, indirect tensile strength test, IDEAL CT, uniaxial compression test, and resilient modulus test, were carried out to assess the performance of the prepared recycled asphalt mixtures. SEM images revealed the presence of the medium to fine particles on RCA indicating the rough surface texture. Except RAP10 (10% RAP plus 40% RCA) and RAP50 (50% RAP) mixes, all mixes had Marshall stability value greater than the control mix, the highest for RAP40 (40% RAP plus 10% RCA) mix followed by RAP0 (50% RCA) mix. In the case of resilient modulus, the effect of RAP is more pronounced till 40% resulting in an almost linear increase in values. Also, RAP40 exhibited the highest rutting and fatigue resistance. As far as moisture sensitivity is concerned, all the mixes performed satisfactorily as the tensile strength ratio (TSR) was greater than 80%. Overall, the major factors affecting the performance of recycled mixes were surface roughness, stiffness of the aged binder and rejuvenator.

Evaluation of HMA Modified with Titan Polymer

Improving the quality of the road pavement and ensuring the safety of the drivers on the road are issues of paramount importance. Cracking and rutting are two of the most common damages that occur to asphalt pavement due to environmental effects and traffic. Utilizing a modified binder is a solution for improving the pavement's resistance to these damages and enhancing pavement durability. This study investigates the performance of Hot Mix Asphalt (HMA) modified with Titan7205 polymers and then compares it with that of a control mix of modified HMA with Styrene-Butadiene-Styrene (SBS) or crumb rubber (CR). Two percentages of Titan7205 were utilized to find out which dose provided better performance. HMA was prepared by adding polymers with different percentages (3% and 5% Titan7205, 4% SBS, and 8% CR). After preparing the samples, they were tested (unconditioned and AASHTO R30) for Dynamic Shear Rheometer (DSR) testing, Cantabro Mass Loss (CML), Tensile Strength Ratio (TSR), and Indirect Tensile Tension (IDT). The results showed that the mix with 3% of Titan7205 has a similar or better performance than the mixes with the other polymer additives utilized in this study.

Effects of Coarse Aggregate Rap Content on the Mechanical and Shear Performance of HMA by the UPT Method

Abstract In recent years, the use of materials derived from recycled asphalt has attracted the attention of airfield and highway construction researchers. Since the making of these products is economically cost-effective, one idea about how to use them is to use coarse-grained crumbs from recycled Asphalt Pavement (RAP), which are agglomerates that can be found in coarse RAP, as a replacement for virgin asphalt.The goal of the current study is to investigate the performance of hot mix asphalt created with various percents of RAP. The punching shear strength of cylindrical specimens versus the penetration of steel rods with fixed and determined diameters into an asphalt specimen is one of the tests used to study the shear strength of asphalt. Other typical tests include a test of the structural strength and resilient modulus with two rectangular and sinusoidal loading shapes, respectively, as well as the specimen's strength against different temperatures of asphalt mixtures containing 10, 20, and 30% coarse-grained RAP. The results show that the resilient strength of the samples with a maximum 30% coarse-grained RAP is within reasonable limits. Furthermore, the semi-sinusoidal loading has a higher resilience modulus than rectangular loading. It is also observed during uniaxial penetration testing (UPT) that increasing the RAP increases the penetration of the steel rod, thereby implying that the shear strength of the asphalt has decreased.

Performance of hot-mix asphalt using polymer-modified bitumen and marble dust as a filler

Marble dust waste powder generated by the marble cutting industry has a high alkalinity. In this research, the use of marble dust (MD) as a mineral filler substitute in hot mixed asphalt (HMA) was evaluated. The Marshall mix design was used to determine the optimum bitumen content (OBC) for all of the mixtures. For each of the four MD contents, i.e., 0, 2%, 4%, and 6% by weight of the total aggregates, four different bitumen percentages were used. The results of the Marshall stability test showed that the optimum filler content was 4% MD. Samples were prepared with 0 MD in the control mix and varying percentages of MD as an alternate filler. In addition, MD aided in increasing the Marshall stability, rutting resistance, and permanent deformation and reduced the fatigue life of asphalt mixtures. As the percentage of MD increases, the rutting resistance and stiffness at high temperatures both increase. As the percentage of MD increases, the fatigue life reduces. Rut resistance in high-temperature conditions can be improved by using MD in HMA as a partial substitute for stone dust (SD). In areas where extensive MD waste is present, MD can be incorporated into HMA mixtures instead of conventional fillers.

Effect of mastic specifications on the fatigue and low-temperature performance of hot mix asphalt

ABSTRACT This study aimed to evaluate the effect of mastic specifications on the intermediate and low temperatures performance of hot mix asphalt. In this research study, four different asphalt mixtures were fabricated with two types of aggregate and bitumen at three different mastic densities (defined as F/B ratios). At intermediate temperature, Four-Point Bending (4PB) beam fatigue tests were carried out at 8 Hz frequency and the strain levels of 460, 750, and 1100 microstrain. Also, the low-temperature performance of mixtures was evaluated by using Semi-Circular Bending (SCB) tests at −6°C, −18°C and −12°C, −24°C for PG 64–16 and PG 58–22 fabricated mixtures, respectively. Fatigue test results showed that the fatigue life of asphalt mixtures was more influenced by the mastic density at the lower strain level. Moreover, a minimum mastic density was necessary for improving fatigue performance. The SCB test results revealed that increasing the mastic density makes higher values in the mixture’s fracture energy, fracture toughness, cracking resistance index (CRI), and tensile strength. Also, the low-temperature performance of asphalt mixtures containing aggregate with a high abrasion value (AAV) was more dependent on the mastic density.