Durability Of Asphalt Pavement Research Articles

A novel approach to determine mode II fracture toughness of hot mix asphalt

Fracture behaviors of hot mix asphalt (HMA) are critical to the durability of asphalt pavement, especially at low temperatures. This study proposed a method to test the mode II fracture behaviors of HMA, which is inspired by the mode II test of cement concrete. In this method, compressive tests were conducted on two types of specimens, including the double-edged notch specimen and the cubic specimen. The shear action resulting in the mode II fracture was extracted from the energy difference between the load–displacement curves of the two types of specimens. The stress intensity factor (KII) and fracture energy (GF) were calculated from the theory of energy consumption. On the other hand, the effects of reclaimed asphalt pavement (RAP) and rejuvenator were examined on the mode II fracture performance of HMA. Meanwhile, asymmetric semi-circular bending (SCB) tests were also conducted to obtain the mode II KII and GF, which were used to verify the feasibility of the method proposed in this study. Results indicated that with the increase of RAP, KII and GF both decreased remarkably. When RAP content was 100%, KII and GF were reduced by 42.8% and 55.8%, respectively. When the rejuvenator and 75% RAP were added, the fracture performance was enhanced compared to HMA with 75% RAP only, indicating rejuvenator benefited the mode II fracture resistance. The result comparison between the double-edge notched specimens and the SCB specimens verified the feasibility of the method proposed in this study.

Study on Rheological Properties of Graphene Oxide/Rubber Crowd Composite-Modified Asphalt.

In order to improve the durability of asphalt pavement and prolong the service life of heavy traffic asphalt pavement, graphene oxide (GO) and rubber powder (RP) were used as composite modifiers to modify matrix asphalt. The high-temperature rheological properties of composite-modified asphalt at different temperatures and frequencies were analyzed. The influence of different stress levels on the viscoelastic properties of composite-modified asphalt was evaluated. The low-temperature rheological properties of composite-modified asphalt were studied. The difference between RP-modified asphalt and GO/RP composite-modified asphalt was analyzed, and the mechanism of GO and RP on asphalt modification was explored. The results show that the composite-modified asphalt has good rheological properties at low temperature, relatively smooth surface and stable network structure, which improves the segregation problem of RP in matrix asphalt. At present, GO and RP are rarely used as composite modifiers to modify matrix asphalt at home and abroad, which is an innovation in material selection.

Incorporating New Technologies in Road Industry: Test Track in Antwerp, Belgium

Numerous factors may disrupt pavement construction including human errors and unforeseen changes in the environmental conditions. These incidents can shorten pavement life span. New technologies recently came to the aid of contractors and road agencies to detect and possibly mitigate undesirable impacts of unpredictable incidents during the asphalt paving process as well as monitoring pavement performance during pavements service life. In this study, several technologies including layer thickness assessment (using both MIT-scan device coupled with metal plates and conventional topographical technique), infrared thermal camera, intelligent roller compactors, and density gauge devices were utilized to develop a coherent construction system and improve the durability of asphalt pavements in Antwerp, Belgium. The data collected in situ were compared with the characterized cores in the laboratory. It was clear that several factors can influence the outcome of the employed devices. For instance, surface temperatures obtained from an infrared camera fluctuated when the camera tilted from the perpendicular axis. Such discrepancies may be associated with the changes in the distance and environmental condition that affect the refraction of the infrared spectra. It was also found that an elaborated data collection format is essential to clearly understand the correlations between the results of the employed technologies.

Study on the Change Law of Performance and Regeneration Mechanism of Aging SBS Modified Asphalt

This paper starts from the research status of SBS modified asphalt aging and regeneration mechanism at home and abroad , and summarizes the performance change law and regeneration mechanism of SBS modified asphalt. Asphalt aging is the main factor that affects the durability of asphalt pavement, and then reduces the service life of the pavement. Through the analysis of the aging status of SBS modified asphalt, the performance change law of aging SBS modified asphalt is analyzed from the microscopic and macroscopic perspectives. The influence factors of multiple aging, rejuvenating agent and regeneration method on the regeneration mechanism of aging SBS modified asphalt . The study of asphalt performance provides reference and reference.

Evaluation of Fatigue Behavior of Asphalt Layers Containing Nanosilica Modified Tack Coat

Generally, the maintenance of asphalt pavements contributes a significant portion of the national capital of the countries. Rutting and cracking cause extensive damage to asphalt pavements, although fatigue cracks are more common in asphalt pavements. Adhesion and bonding between asphalt layers are among the factors that affect the durability of asphalt pavement and play a major function in maintaining the integrity of the pavement. On the other hand, using nanomaterials is regarded as one of the options to improve the properties and performance of bitumen. Therefore, this study aimed to evaluate the fatigue behavior of asphalt layers containing nanosilica modified tack coat (NSMTC). To this aim, it was used a four-point bending (4 PB) beam fatigue test. The loading is the semisinusoidal type with 10 Hz frequency, without rest, and at a temperature of 20°C. The controlled strain state (at three strain levels of 400, 550, and 700 με) is implemented. The results revealed the increased fatigue life in the specimen of asphalt beam containing NSMTC. At different strain levels (i.e., 400, 550, and 700 με), the fatigue life of beams with NSMTC increased by 18, 15, and 57%, respectively. Furthermore, the cumulative dissipated energy of specimens containing NSMTC increased by 37, 42, and 60% compared to specimens containing unmodified tack coat (UMTC) for strain levels of 400, 550, and 700 με, respectively.

Evaluation of cracking resistance of warm mix asphalt incorporating high reclaimed asphalt pavement content

Incorporating high Reclaimed Asphalt Pavement (RAP) content in manufacturing Warm Mix Asphalt (WMA) is more commonly used thanks to its economic efficiency and environmental effectiveness. However, when high RAP content is incorporated, the mixture's cracking tolerance needs to be controlled to achieve the durability of asphalt pavement. The present experimental work investigates the cracking tolerance of asphalt mixtures through a Flexibility Index (FI) and a Cracking Tolerance Index (CTIndex). For this purpose, warm-mix asphalt mixtures using Sasobit and Zycotherm additives are produced with RAP content at 30%, 40%, and 50%, respectively. The obtained results are also compared with Hot Mix Asphalt (HMA) with RAP content at 0% and 30%. The results show that, compared with HMA using 30% RAP, WMA using Sasobit has lower FI (12.1%), and WMA using Zycotherm exhibits higher FI (58.64%). Similarly, WMA using Sasobit has a lower CTIndex (12.8%), and using Zycotherm has a higher CTIndex (105.6%), compared with HMA using the same RAP content. Moreover, the results also show that the FI and CTIndex of WMA using Zycotherm are higher than Sasobit with similar RAP content. These values decrease with increasing RAP content. Lastly, the RAP content that ensures cracking tolerance could reach 40% in WMA mixtures using Zycotherm.

Preparation and Temperature Susceptibility Evaluation of Crumb Rubber Modified Asphalt Applied in Alpine Regions

In alpine regions, the durability of asphalt pavement is worse due to the harsh climate. However, crumb rubber modified asphalt has the potential to improve the durability of pavement. Based on matrix asphalt, crumb rubber, Trans-Polyoctenamer Rubber Reactive Modifier (TOR), and an orthogonal test, the preparation scheme of crumb rubber modified asphalt suitable for alpine regions was obtained. The crumb rubber was selected 30 mesh, and the content of crumb rubber was 24% of the quality of matrix asphalt. Shearing time was 60 min, and preparation temperature was 205 °C. Shearing rate was 5000 r/min, and optimum TOR content was set as 4.5% of the quality of crumb rubber. The temperature susceptibility of matrix asphalt (JZ), crumb rubber modified asphalt (AR), crumb rubber modified asphalt mixed with TOR (TAR) was investigated. The high temperature performance indexes, including phase angle, the complex modulus index, and rutting factor, and the low temperature performance indexes including creep rate and stiffness modulus, the ratio of creep rate and stiffness modulus, Burgers model parameters, dissipated energy ratio, and the derivative of creep compliance were analyzed in depth with multiple parameters. Meanwhile, the mechanisms of prepared AR and TAR were explored. The results indicate that the PG grading is PG64-22 of JZ, PG70-34 of AR, and PG82-28 of TAR. The deformation resistance of TAR at high temperature is superior to AR. The addition of crumb rubber not only improves the temperature susceptibility, but also enhances its viscoelasticity at low temperatures. After the crumb rubber swell in the asphalt system, the network structures are crosslinked and the physical and chemical effects are produced, such as cracking and repolymerization in the asphalt system. TOR can further enhance the swelling and network crosslinking effects of rubber-asphalt. The TAR has the strongest weather resistance. The study provides guidance for AR and TAR to be used in alpine regions.

Asphalt Pavement Compaction Control: Relevance of Laboratory and Non-Destructive Testing Methods of Density

Assurance of asphalt pavement layer compaction, expressed by air voids ratio between field and laboratory bulk density, is one of the main criteria of the asphalt pavement durability. Thus, destructive measures should be applied, and many asphalt samples should be taken on site in order to determine the representative compaction level of constructed pavement. With the fast development of technologies, new methods should be considered for fast, non-destructive and accurate determination of asphalt bulk density on site. As there are quite few non-destructive methods related to asphalt pavement density measurement, there is a need to make comparison of such methods. Currently, when GPR methods are used to determine the density, calibration cores are used in all cases to estimate the unknown or unmeasured variables or conditions that may affect the results of dielectric value measurements. The aim of this study is to develop a regression model that can predict the bulk density of the compacted asphalt layer without coring, using the design values of the bulk density determined in the type tests of asphalt mixtures or other currently used non-destructive testing technologies (in this case PQI and NDG) and GPR measured dielectric constant values.

Study on the Durability of Acid Rain Erosion-Resistant Asphalt Mixtures.

Acid erosion can accelerate the process of early damage of asphalt pavement and decrease the durability of asphalt pavement. However, there are limited research results for asphalt mixtures that can resist acid rain erosion. To systematically evaluate the impact and action law of acid rain erosion on the durability of asphalt mixtures, three gradation schemes were used: periodic dry–wet cycle immersion test, contact angle test and road performance test. The acid rain erosion resistance of epoxy asphalt mixture, SBS-modified asphalt mixture and 70# matrix asphalt mixture were tested from three aspects of anti-aging performance, freeze–thaw cycle performance and fatigue performance. The results show that the erosion of acid rain can significantly decrease the adhesion between asphalt and aggregate, and affects the road performance of the asphalt mixture. Acid rain erosion can significantly decrease the mechanical properties, adhesion and durability of asphalt mixtures. Epoxy asphalt has better physical properties, adhesion and acid rain erosion resistance than 70# matrix asphalt and SBS-modified asphalt. Epoxy asphalt has excellent adhesion due to its polar group, high cohesion and thermosetting resin with low shrinkage, which can effectively resist moisture erosion, spalling and temperature stress cracking, thereby effectively resisting the erosion of acid rain. Epoxy asphalt mixture has the strongest acid rain erosion resistance, which can be further enhanced when used together with waste rubber powder and modified bamboo fiber. On the whole, asphalt mixture with high-density structure and thicker asphalt film can effectively resist acid rain erosion. The durability of asphalt concrete (AC)-type gradation mixture and stone mastic asphalt (SMA)-type gradation mixture are equivalent, and both are superior to open-graded friction courses (OGFC)-type gradation mixture. The gradation of asphalt mixtures and the type of asphalt binder have great influence on their acid rain erosion resistance and durability. In order to realize the directional control of the acid rain erosion resistance and durability of different asphalt mixtures, a multi-parameter comprehensive assessment indicator system between the type and property of asphalt, the gradation of asphalt mixture, and the acid rain resistance and durability of the mixture need to be established in the future.

Development of Cost-Effective High-Modulus Asphalt Concrete Mixtures Using Crumb Rubber and Local Construction Materials in Louisiana

One of the emerging solutions to enhance the durability of asphalt pavements is the use of a French asphalt mix known as “High-Modulus Asphalt Concrete (HMAC).” This mix uses a hard asphalt binder, high binder content (about 6%), and low air voids content as compared with Superpave mixtures. The key objective of this study was to develop a cost-effective HMAC mixture using crumb rubber and local materials in Louisiana. To achieve this objective, four HMAC mixtures were prepared using two asphalt binders (PG 82-22 and PG 76-22 plus 10% crumb rubber) and two Reclaimed Asphalt Pavement (RAP) contents (20% and 40%); additionally, a conventional Superpave mixture in Louisiana was prepared as a control mixture. The laboratory performance of these five mixtures was evaluated in relation to workability, dynamic modulus, rutting resistance, and cracking resistance. The AASHTOWare Pavement ME Design software was also used to estimate the long-term field performance of these mixtures. Results indicated that the HMAC mixture prepared with 10% crumb rubber and 20% RAP successfully met the French mix design specifications for HMAC and LaDOTD specifications. This HMAC mix outperformed the control Superpave mix in relation to dynamic modulus, rutting resistance, and cracking resistance. Additionally, this HMAC mixture can reduce the required asphalt thickness by 1.5 or 2 in. based on traffic level. The cost-effectiveness analysis indicated that this HMAC mixture was more cost-effective than conventional Superpave mixtures in Louisiana. In addition, this mixture is environmentally friendly as it can reduce the disposal of scrap tires in landfills.

Investigation on Fatigue Performance of Diatomite/Basalt Fiber Composite Modified Asphalt Mixture.

The fatigue resistance of asphalt mixture is an important indicator to evaluate the durability of asphalt pavement. In order to improve the fatigue properties of asphalt mixture, diatomite and environmental basalt fiber were added. Four types of asphalt mixtures, ordinary asphalt mixture (AM), diatomite modified asphalt mixture (DAM), basalt fiber modified asphalt mixture (BFAM) and diatomite/basalt fiber composite modified asphalt mixture (DBFAM), were chosen, whose optimum asphalt–aggregate ratio, optimum content of diatomite and optimum content of basalt fiber could be determined by Marshall test and response surface methodology (RSM). The multi-functional pneumatic servo Cooper test machine was carried out by a four-point bending fatigue test. Through the comparative analysis of flexural-tensile stiffness modulus (S), initial stiffness modulus(S0), residual stiffness modulus ratio, lag angle (ϕ) and cumulative dissipation energy (ECD), the fatigue resistance of asphalt mixture can be effectively improved by adding diatomite and basalt fiber. Grey correlation analysis was also used to analyze the degree of correlation between the fatigue life and the influencing factors such as VV, VMA, VFA, OAC, S, and ECD. The analysis results indicate that ECD has the greatest impact on the fatigue life of the asphalt mixture.

Evaluation of rheological and aging behavior of modified asphalt based on activation energy of viscous flow

Styrene–butadiene–styrene (SBS) is one of the most widely used polymer modifiers for the improvement of the durability of asphalt pavement. SBS functionalization can improve the low-and high-temperature performance and aging resistance of asphalt binders. This paper systematically explores the feasibility of the activation energy of viscous flow (Ea) in evaluating the rheological and aging behavior of functionalized SBS-modified asphalt binders, including SBS-, styrene–ethylene/butylene–styrene (SEBS)-, SEBS-grafted maleic anhydride (MAH)-, and SBS/organic montmorillonite (OMMT) nanocomposites- modified asphalts (SBS-A, SEBS-A, MAH-A, and OSBS-A for short). The Ea values of different functionalized materials were calculated by Arrhenius equation based on Dynamic Shear Rheometer (DSR) and Rotational Viscosimeter (RV) tests, which means that the viscous flow behavior were analyzed at different temperature ranges. Ea based on RV test, the rutting factor and rutting factor aging index came to the same conclusion, that is, SEBS-A and OSBS-A with higher Ea values (lower temperature sensitivity) show excellent rheological properties and better aging resistance, followed by SBS-A, MAH-A, and base asphalt (BA). Besides, Ea based on DSR test was higher than Ea based on RV test, which is related to physical phase (visco-elastic phase and viscous phase). From the perspective of the viscous flow behavior of the binders, Ea based on RV test provides scientific and effective methods for probing the effect of SBS functionalization and designing high capability materials for pavement.

Relating Ndesign to Field Compaction: A Case Study in Minnesota

High field density helps in increasing the durability of asphalt pavements. In a current research effort, the University of Minnesota and the Minnesota Department of Transportation (MnDOT) have been working on designing asphalt mixtures with higher field densities. One critical issue is the determination of the Ndesign values for these mixtures. The physical meaning of Ndesign is discussed first. Instead of the traditional approach, in which Ndesign represents a measure of rutting resistance, Ndesign is interpreted as an indication of the compactability of mixtures. The field density data from some recent Minnesota pavement projects are analyzed. A clear negative correlation between Ndesign and field density level is identified, which confirms the significant effect of Ndesign on the compactability and consequently on the field density of mixtures. To achieve consistency between the laboratory and field compaction, it is proposed that Ndesign should be determined to reflect the real field compaction effort. A parameter called the equivalent number of gyrations to field compaction effort (Nequ) is proposed to quantify the field compaction effort, and the Nequ values for some recent Minnesota pavement projects are calculated. The results indicate that the field compaction effort for the current Minnesota projects evaluated corresponds to about 30 gyrations of gyratory compaction. The computed Nequ is then used as the Ndesign for a Superpave 5 mixture placed in a paving project, for which field density data and laboratory performance test results are obtained. The data analysis shows that both the field density and pavement performance of the Superpave 5 mixture are significantly improved compared with the traditional mixtures. The results indicate that Nequ provides a reasonable estimation of field compaction effort, and that Nequ can be used as the Ndesign for achieving higher field densities.

Analysis of Segregation Tendency of Aggregates Based on Composite Geometric Characteristics

AbstractAggregate segregation is an important factor affecting the early distress and durability of asphalt pavement. To analyze the segregation tendency of aggregates on the mesoscopic scale, firs...

Effect of aging and rejuvenation on adhesion properties of modified asphalt binder based on AFM.

The adhesion between asphalt binder and aggregate is very important to the performance and durability of asphalt pavement. In order to explore the characterisation of modified asphalt binder in microstructure during aging and rejuvenation, the virgin asphalt binder and three kinds of modified asphalt binder (styrene-butadiene-styrene block copolymer (SBS), rubber powder and high viscosity and high elasticity [HVHE] modifier) in different aging and rejuvenation condition were prepared. The micromorphology and surface adhesion were measured by atomic force microscopy. The average roughness value was used as the index to evaluate the micromorphology of asphalt binder. The surface adhesion was used as the index to evaluate the adhesion properties of asphalt binder. Results show that the "bee" structure of SBS-modified asphalt binder increased slightly after long-term aging, and the recovery effect of aromatics oil was the closest to that of the unaged one. The rubber powder-modified asphalt binder and HVHE-modified asphalt binder showed the spot structure. And no matter for short-term aging or long-term aging, aromatics oil had the best recovery effect on micro morphology. The adhesion of the three modified asphalts would decrease gradually after aging. The effects of three kinds of rejuvenator on the adhesion of SBS-modified asphalt binder and rubber powder-modified asphalt binder were different. Rejuvenator, aromatic oil and warm mix asphalt mixture (WMA) additive could rejuvenate the loss of adhesion of HVHE-modified asphalt binder to a certain extent.

Modelling the stiffness development in asphalt concrete to obtain fatigue failure criteria

The study of fatigue is critical to good usability and durability of asphalt pavements. Inaccurate calculation of the fatigue failure criteria can cause incorrect evaluation of the fatigue performance, leading to inaccurate prediction of the pavement performance and poor maintenance planning. This paper develops a stiffness change tendency method (SCTM) that can be used to model the stiffness evolution in asphalt concrete and determine critical laboratory fatigue failure points to characterise different fatigue damage stages. A logistic model was selected to represent the relationship between the log of the stiffness (E) and the log of the number of cycles (N) obtained from two-point bending (2PB) fatigue tests. The measured stiffness reduction versus loading curves were determined for a range of asphalt mixtures in unaged, aged and moisture damaged conditions by testing at various temperatures and strains. By analysing the derivatives of the logistic model, it is possible to identify three transition points associated with fatigue progression. There is good agreement between the laboratory data and the logistic model proposed, confirming that the logistic model is a good approximation to the stiffness reduction curves. The number of loading cycles associated with the first two transition points in the SCTM (NP1 and NP2) were compared to the value of N1 and Nfm obtained from the energy ratio (ER) method and the ratio of dissipated energy change (RDEC) method, respectively. There are no statistically-significant differences between the SCTM and two energy-based methods, proving that P1 can be viewed as the number of cycles to micro-crack initiation and propagation, and P2 can be defined as the macro-crack generation point (the true failure point). Three different mixtures are subjected to four-point bending (4PB) fatigue tests to demonstrate the applicability of the SCTM with different bitumen types, mixture grades and test methods. The SCTM provides a method to model stiffness development, obtain different fatigue failure criteria and characterise different fatigue damage stages, which could be useful in a simulation of pavement deterioration.

Effectiveness of Loaded Wheel Tracking Test to Ascertain Moisture Susceptibility of Asphalt Mixtures

Moisture damage of asphalt mixtures is a major distress affecting the durability of asphalt pavements. The loaded wheel tracking (LWT) test is gaining popularity in determining moisture damage because of its ability to relate laboratory performance to field performance. However, the accuracy of LWT’s “pass/fail” criteria for screening mixtures is limited. The objective of this study was to evaluate the capability of the LWT test to identify moisture susceptibility of asphalt mixtures with different moisture conditioning protocols. Seven 12.5 mm asphalt mixtures with two asphalt binder types (unmodified PG 67-22 and modified PG 70-22), and three aggregate types (limestone, crushed gravel, and a semi-crushed gravel) were utilized. Asphalt binder and mixture samples were subjected to five conditioning levels, namely, a control; single freeze–thaw-; triple freeze–thaw-; MiST 3500 cycles; and MiST 7000 cycles. Frequency sweep at multiple temperatures and frequencies, and multiple stress creep recovery tests were performed to evaluate asphalt binders. LWT test was used to evaluate the asphalt mixture samples. Freeze–thaw and MiST conditioning resulted in an increase in stiffness in the asphalt binders as compared with the control. Further, freeze–thaw and MiST conditioning resulted in an increase in rut depth compared with the control asphalt mixture. The conditioning protocols evaluated were effective in exposing moisture-sensitive mixtures, which initially showed compliance with Louisiana asphalt mixture design specifications.

Improved Adhesion Bond between Asphalt Binder-Aggregate as Indicator to Reduced Moisture Damage

Improving the adhesion bonding strength between asphalt-aggregate combinations has a significant influence on the field performance and durability of asphalt pavement and minimizing the moisture damage that can appear in form of losing adhesion in asphalt-aggregate system by using modifiers will increase the service life of pavements.The work of adhesion, de-bonding work, wettability and energy ratios were estimated based on surface free energy theory to evaluate the potential moisture-induced damage of combinations of pure and modified asphalt binders by (Styrene–Butadiene Styrene (SBS), Butyl Rubber (BR), and anti-stripping agent BG plus) with different types of aggregate. The sessile drop method is used to determine the components of the surface energy of different aggregate and asphalt binder types by performing direct contact angle measurements.The experimental results showed that in general, the addition of SBS and BR modifiers will increase adhesion work and decrease de-bonding work and decrease ER2 and wettability for both types of asphalt binders and aggregates while the addition of an anti-stripping agent (BG plus) caused a reduction in adhesion work and de-bonding work and increase ER2 and wettability between the asphalt binder and aggregate surface and that will provide a better possible aggregate-asphalt binder bond strength and asphalt mixture’s resistance to moisture-induced damage.

Assessment of the effect of the use of highly-modified binder on the viscoelastic and functional properties of bituminous mixtures illustrated with the example of asphalt concrete for the binder course

Polymer-modified binders (PMB) have been known and used for many years to increase asphalt pavement durability. The most commonly used polymer is the SBS elastomer (styrene–butadienestyrene). Its content in the classic polymer-modified binder ranges from 2 to 4% m/m (by weight). In such a case, it fills up to 40% of the binder’s volume to form a polymer network. In highly-modified asphalt binder (HiMA), the amount of polymer is twice as large and reaches a level of 7–8% m/m, which means that the polymer phase in binder volume dominates the asphalt phase. The extensive continuous polymer network additionally causes significant changes in the properties of the binder. Highly-modified binders have been available on the Polish market for several years. This article assesses the impact of the use of highly-modified binder on the properties of asphalt concrete for the binder course. As reference, a test programme also included three other bituminous binders used in Poland. The assessment took into account the basic and functional properties of mixtures over a wide temperature range, as well as failure mechanisms most relevant for the binder course. Testing included resistance to water, complex modulus, resistance to permanent deformations, resistance to low temperature cracking and tensile strength. Other important characteristics such as fatigue resistance have been tested for mixes for the base course, which is outside the scope of this article. Test results were subject to analysis, which indicated that the use of HiMA for the asphalt concrete mixture significantly alters the viscoelastic properties and has a positive effect on strength and functional properties of the mixture. Analyses were carried out to show distinct relationships between viscoelastic characteristics and other properties.

Effects of crystalline wax and asphaltene on thermoreversible aging of asphalt binder

ABSTRACT Thermoreversible aging is an important factor that affects the durability of asphalt pavement in cold and high altitude areas. Although there has been increasing attention to the significance of thermoreversible aging in recent years, the contribution of asphalt components to thermoreversible aging remains unclear in the existing literature. To this end, potential components that may affect the thermoreversible aging of asphalt binders were regarded as additives in this study. The extended bending beam rheological test (ExBBR), thermal stress calculation, and modulated differential scanning calorimetry (MDSC) analysis were employed to study the effects of two kinds of crystalline waxes with different carbon atoms and one asphaltene type as additives on the thermoreversible aging properties of asphalt binder. The findings showed that under conventional 1-hr conditioning cold storage, adding 1% or 3% C20H42 significantly improved the low-temperature rheological properties and reduced base asphalt's thermal stresses. However, no significant effect of the C20H42 additive on thermal stress reduction was observed when considering the asphalt binder's thermoreversible aging. Both low-temperature rheological tests and thermal analysis confirmed that C20H42 significantly increased thermoreversible aging in the base binder; however, C32H66 and asphaltene additives did not produce a similar effect.