Search

With the increase in asphalt mixtures sustainability, the application of waste as a bitumen modifier has been encouraged. In addition, the asphalt mixtures produced considering only the engineering properties show degradation due to repetitive traffic loading and not the performance properties. Thus, necessitate the use of an alternative mix design considering various properties and considering alternative modifiers. Also, there are limited studies on the impact of long-term water immersion on the strength of asphalt mixtures, particularly the effects of both immersion-drying (I-D) cycles on Palm oil clinker fine-modified bitumen (POCF-MB). Thus, this study employed palm oil clinker fine (POCF) as a bitumen modifier. Response surface methodology (RSM) was used to evaluate an alternative engineering and performance mix design technique for asphalt mixtures was examined. Subsequently, the durability and strength of the optimized POCF-MB asphalt mixture for both I-D cycles were evaluated. Samples were vacuum saturated and immersed for 0 (dry) 1, 3, 5, and 7 days. Then assessed in terms of Marshall quotient (MQ), retained Marshall stability (RMS), swelling index (SI), indirect tensile strength (IDT), Indirect tensile strength ratio (ITSR), and subsequently redried at ambient temperature to evaluate the retained durability and strength. The RSM findings show that the synergetic effects of POCF dosage and bitumen significantly impact performance. Based on the high coefficients of determination (R2) values (> 0.95), high adequate precision values (> 4), and low p-values for all responses, the statistical models were determined to be significant and well-fitted. The optimum values of numerical optimization were 5.86% POCF dosage and 4.65% bitumen content. The validation test shows an error margin of < 5% for all responses indicating that the model and experimental values agree well and are closely aligned. With increasing conditioning time, all samples showed increased SI, flow, and a decline in MQ, RMS, IDT, and ITSR. However, POCF-MB samples showed minimal moisture durability reduction, which can be attributed to the hydration process of the POCF, making the mixtures stiffer. After redrying POCF-MB samples show a higher recovery of their initial durability, revealing that the durability and strength properties of the asphalt mixture are recoverable. [ABSTRACT FROM AUTHOR]

Incontinence-associated dermatitis, previously and sometimes still referred to as moisture lesions or moisture damage, is a commonly seen contact dermatitis that is a reactive response of the skin to chronic contact to urine and faecal matter. Understanding the etiology is fundamental to creating a skin care plan and successfully prevention. Systemic reviews and studies have shown that the continued variability in management results from a combination of knowledge base, observation, diagnosis, and product selection. This article aims to improve clinicians' understanding of incontinence-associated dermatitis and its management. [ABSTRACT FROM AUTHOR]

Society must move towards an economy in which sustainability is its main driving force. A sustainable solution to avoid sending waste to landfill, the consumption of raw materials and, therefore, the depletion of natural resources, is the reuse or recycling of waste. Here, pavement engineering has great potential, as waste can be used for the manufacture of bituminous mixes. In particular, one of these residues is Marpol, which is generated during shipping, maintenance and cleaning operations, including wastewater and waste other than cargo waste. There are few studies on the analysis of its use in mixtures. Thus, in this work, the effect of partially replacing the binder of bituminous mixtures for another obtained from the treatment of Marpol oily waste was studied in order to contribute to environmental sustainability and circular economy. For this, water sensitivity, deformation and cracking resistance were analysed of two asphalt mixtures whose binder was partially replaced by Marpol binder. Furthermore, the binder ageing resistance was studied. The results obtained from the laboratory, plant and test section mixture were very close to those obtained for the reference. These results have demonstrated the feasibility of partially replacing the conventional binder by one obtained from Marpol waste. [ABSTRACT FROM AUTHOR]

Reclaimed asphalt pavement (RAP) mixtures reduces environmental burden by utilising existing pavement material. However, RAP percent is limited due to performance issues at higher RAP content due to improper blending. The degree of blending can be improved using rejuvenator. Waste cooking oil (WCO) is gaining attention as a potential rejuvenator in recycled mixtures. However, past studies have shown contradictory results on WCO influence in asphalt mixture and have not investigated the influence of WCO on blending. This study is devised with a methodological approach to investigate the influence of WCO on blending in asphalt mixtures. Four blending approaches were formulated with four RAP and WCO contents resulting in a total of 148 mixture combinations. The blending characteristics were evaluated by assessing the workability and moisture damage resistance. The optimum mixtures were determined by Grey relational analysis, which were further investigated. The results showed the WCO doses determined from blending equation resulted in the higher dose than optimum WCO. The mixtures with medium dose and dry mixing of WCO showed the highest resistance to moisture damage. Further, for utilising higher than 30% RAP, higher binder content is required as compared to conventional mixture to increase the functional binder in the mixture. [ABSTRACT FROM AUTHOR]

The effects of short-term aging (STA) and long-term aging (LTA) on moisture damage mechanisms were investigated using mechanical and thermodynamic methods. PG58-22 and PG64-16 asphalt binders modified with Dodecylamine (DA) and Wetfix (WT) additives and limestone and granite aggregates were used. The moisture sensitivity was assessed using the indirect tensile strength (ITS) test via the modified Lottman test and the surface free energy (SFE) method. As asphalt binder becomes harder due to aging, ITS values increase in dry conditions. However, ITS values decrease due to the texture and mineralogical properties of aggregates, the reduction of mastic cohesion and asphalt binder-aggregate adhesion because of water infiltration and weakening of the mixture in wet conditions. The tensile strength ratio (TSR) test revealed that TSR values decrease due to aging. The cohesion free energy of the PG64-16 asphalt binder increased by 8.9% in the STA state and by 29.8% in the LTA state compared to the unaged state. This rise in PG58-22 was about the same as that in PG64-16. Asphalt binder aging in all the samples reduced the adhesion energy. These variations indicated that aging reduces the probability of cohesion failure and increases the probability of adhesion failure. [ABSTRACT FROM AUTHOR]

The main objective of this study is to investigate the effect of moisture damage on the fatigue and cracking behaviors of warm mix asphalt (WMA) containing reclaimed asphalt pavement (RAP). To achieve this aim, different fatigue and cracking tests such as indirect tensile fatigue failure, four point beam fatigue, and semicircular bending tests have been conducted, and several parameters have been obtained. These parameters include tensile strength ratio (TSR) and fracture energy ratio (FER), indirect tensile fatigue ratio (IDTR), peak load ratio (PLR), J-integral ratio, and flexibility index (FI), and Nf and flexural stiffness ratios. The results showed that moisture-damaged RAP-WMA demonstrated slightly weaker fatigue and cracking resistance than other mixtures, which is not significant considering the environmental advantages of the mixture. Hence, RAP-WMA would be a proper and beneficial alternative as pavement material where there are significant problems in supplying natural aggregates, and issues like moisture damage and being environment friendly are big concerns. Also, it has been concluded that the fatigue test condition (stress and strain control modes) had a significant effect on the moisture damage investigation. [ABSTRACT FROM AUTHOR]

Reclaimed asphalt pavement (RAP) mixtures reduces environmental burden by utilising existing pavement material. However, RAP percent is limited due to performance issues at higher RAP content due to improper blending. The degree of blending can be improved using rejuvenator. Waste cooking oil (WCO) is gaining attention as a potential rejuvenator in recycled mixtures. However, past studies have shown contradictory results on WCO influence in asphalt mixture and have not investigated the influence of WCO on blending. This study is devised with a methodological approach to investigate the influence of WCO on blending in asphalt mixtures. Four blending approaches were formulated with four RAP and WCO contents resulting in a total of 148 mixture combinations. The blending characteristics were evaluated by assessing the workability and moisture damage resistance. The optimum mixtures were determined by Grey relational analysis, which were further investigated. The results showed the WCO doses determined from blending equation resulted in the higher dose than optimum WCO. The mixtures with medium dose and dry mixing of WCO showed the highest resistance to moisture damage. Further, for utilising higher than 30% RAP, higher binder content is required as compared to conventional mixture to increase the functional binder in the mixture. [ABSTRACT FROM AUTHOR]

The effects of short-term aging (STA) and long-term aging (LTA) on moisture damage mechanisms were investigated using mechanical and thermodynamic methods. PG58-22 and PG64-16 asphalt binders modified with Dodecylamine (DA) and Wetfix (WT) additives and limestone and granite aggregates were used. The moisture sensitivity was assessed using the indirect tensile strength (ITS) test via the modified Lottman test and the surface free energy (SFE) method. As asphalt binder becomes harder due to aging, ITS values increase in dry conditions. However, ITS values decrease due to the texture and mineralogical properties of aggregates, the reduction of mastic cohesion and asphalt binder-aggregate adhesion because of water infiltration and weakening of the mixture in wet conditions. The tensile strength ratio (TSR) test revealed that TSR values decrease due to aging. The cohesion free energy of the PG64-16 asphalt binder increased by 8.9% in the STA state and by 29.8% in the LTA state compared to the unaged state. This rise in PG58-22 was about the same as that in PG64-16. Asphalt binder aging in all the samples reduced the adhesion energy. These variations indicated that aging reduces the probability of cohesion failure and increases the probability of adhesion failure. [ABSTRACT FROM AUTHOR]

Stone matrix asphalt (SMA) mixtures are the most resistant type of asphalt mixtures today in which the aggregate skeleton bears the bulk load. In this study, the effect of nano hydrated lime (NHL) on the moisture sensitivity of SMA mixtures was investigated. To examine the effect of NHL, the surface free energy (SFE) method and the dynamic modulus (DM) test were applied under wet and dry conditions on mixtures constructed with limestone and granite aggregates. The SFE results indicated that the granite aggregates had a greater polar component and limestone aggregates had a higher non-polar component which shows their higher moisture resistance. The adhesion free energy (AFE) results showed that the adhesion of base bitumen and limestone aggregate was higher, and using NHL improved the AFE values. The results of DM tests indicated that as the load cycles raised, the wet to dry DM ratio reduced and using NHL increased this ratio. The reduction slope of the DM ratio in samples constructed with granite aggregates showed a faster trend compared to limestone aggregates, and using NHL improved the resistance of SMA mixtures constructed with granite aggregates to moisture more than limestone aggregates. [ABSTRACT FROM AUTHOR]

Adhesion is easily affected by moisture erosion, thus reducing pavement performance. SBS modified asphalt is widely used in road engineering due to its excellent performance. For analyzing the adhesion properties between SBS modified asphalt and aggregates under moisture damage, the macro-scale SBS modified asphalt-coated aggregates and micro-scale asphalt-aggregate adhesion models were prepared first. The moisture damage was applied to the coated aggregates and adhesion models subsequently. After that, the quantitative boiling tests and molecular dynamics (MD) simulations were carried out. Finally, the multi-scale adhesion results were analyzed using Pearson correlation analysis. The macro-scale results imply that as the degree of moisture damage increases, the stripping area of the asphalt-aggregate interface rises. The micro-scale results reveal the moisture damage mechanism that is the penetrated moisture into asphalt-aggregate interface disrupt the adhesion force by the action of hydrogen bonds and Van der Waals forces. The Pearson correlation coefficient is 0.996, which indicates that the multi-scale adhesion results present an extremely strong linear relationship. This research contributes to the analysis of moisture damage in asphalt pavements in pluvial as well as seasonal frozen regions, and also provides a reference for correlation analysis between the multi-scale results. [ABSTRACT FROM AUTHOR]

Graphene is an auspicious nanomodified material for asphalt pavements. This study aims to evaluate the effect of graphene composites (GCs) on the adhesion characteristics of asphalt based on surface-free energy (SFE) theory. The surface-free energy of graphene-modified asphalt was measured by the sessile drop method. The work of adhesion and stripping between asphalts and two kinds of aggregates were calculated through using their surface-free energy components. The macroadhesion property between asphalts and aggregates was obtained by the improved boiling method. Immersion Marshall test and freeze–thaw splitting test were conducted to verify the effectiveness of surface-free energy indexes. The results demonstrated that GC significantly increased total surface-free energy and dispersion components of asphalt but reduced the polarity components. The adhesion work between asphalt and both aggregates increased after modification, whereas the stripping work decreased after modification. GC can substantially improve the adhesion and resistance to moisture damage at the asphalt–aggregate interface, and the effect on asphalt-limestone is more obvious. There are strong correlations between macro evaluation indicators and surface-free energy calculated indexes, where the macro indicators are more strongly correlated with stripping work. Limestone is generally better at resisting moisture damage than granite. GC remarkably improved the water stability of the mixture, which further indicates that energy indexes are a good method to quantize the moisture damage resistance of hot mix asphalt (HMA). The high dosage of graphene-modified asphalt is potentially applicable to porous asphalt concrete (PAC) pavement with extra-large voids. [ABSTRACT FROM AUTHOR]

Using geopolymer as a modifier for asphalt binders and mixtures gained momentum for investigation in recent decades. Limited research investigations attempted to link the effect of temperature and traffic loading on the rheological properties and performance of geopolymer-modified asphalt binders. The primary objective of this study is to evaluate the effect of fly ash-based geopolymer (GF), styrene-butadiene-styrene (SBS), and the combination of GF with SBS on the rheological properties and performance of asphalt binders at low and intermediate temperatures. The rheological properties and performance of neat and modified asphalt binders (4%GF, 8%GF,12%GF, 2%SBS, and hybrid (2%SBS+8%GF)) were evaluated utilizing dynamic shear rheometer (DSR) and bending beam rheometer (BBR) devices. To evaluate the fatigue resistance of asphalt binders, the linear amplitude sweep (LAS) and viscoelastic continuum damage (VECD) models were applied. The dynamic or complex modulus and moisture damage resistance were measured to investigate the influence of modifiers on the performance of asphalt mixtures. The findings demonstrated that for both unaged and RTFO-aged asphalt binders, additives reduced the temperature sensitivity of both G′ and G″. When the binders were exposed to long-term aging using a pressure aging vessel (PAV), it was noticed that the 8%GF binder became more susceptible to temperature changes. The 2%SBS binder had the lowest creep stiffness compared with the neat and other modifiers, while the hybrid binder exhibited the highest resistance to fatigue distress at different temperatures compared with the other binders. The modified asphalt mixes (8%GF, 2%SBS, and hybrid) achieved the maximum tensile strength ( S t ) compared with the neat asphalt binder, with an increase of more than 80%. The S t increased from 580.4 kPa to 740.4 kPa, 884.8 kPa, and 917.4 kPa by utilising the 8%GF, 2%SBS, and hybrid binders, respectively. Furthermore, the modified asphalt mixture exhibited more ability to resist cracking, attaining the highest fracture energy in dry and freeze-thaw conditions. [ABSTRACT FROM AUTHOR]

Asphalt pavement failure is directly related to the traffic and climate effects. Temperature and moisture severely impact pavement service life. It is known that moisture changes the stiffness and stress–strain distribution and all the mechanical behaviors of the mixture/structure. There is a huge interest in studying the impact of water on the behavior of flexible pavements, mainly on freeze–thaw regions under tropical climates with high rainfall levels. The scope of the present paper was to check the susceptibility to moisture-induced damage of dense asphalt mixes produced and applied on highways in Brazil's southernmost region using different laboratory tests: visual adhesion of coarse aggregate; tensile strength ratio (TSR), and dynamic modulus ratio (DMR). Thus, this study evaluated the morphological, chemical, and mineralogical properties of aggregates from 11 quarries, as well as the interaction between aggregates and the respective bituminous binders. Rocks with high Si contents performed worse in visual adhesiveness tests; chemical ratios such as Fe/Si above 1 and Ca/K above 5, as well as the rougher texture of aggregates, considerably improved the coating, reducing the failures in adhesion. Results of TSR and DMR, after applying the induced moisture damage cycle, indicated greater susceptibility to conventional binders than mixtures containing modified binders in their composition. The action of moisture damage for most mixtures caused a reduction in strength and stiffness, warning of a decrease in the binder's ability within the mixture, completely changing the distribution of efforts within the structure. Therefore, from this study, it is possible to suggest using DMR instead of TSR to assess susceptibility to moisture damage. [ABSTRACT FROM AUTHOR]

In order to study the influence of dry-wet cycles on the anti-cracking performance of asphalt mixture, a meso numerical model of asphalt mixture was established by using digital image processing technology, and the moisture diffusion coefficients of aggregate and asphalt mortar at different temperatures were measured. Based on Fick's law, the wet state of asphalt concrete under the coupling action of temperature and dry-wet cycles is analyzed. The USDFLD subroutine was used to realize the coupling of moisture concentration and mechanical parameters, the bending failure behavior and crack development of asphalt mixture after dry-wet cycles were simulated and analyzed. The results show that the cohesive damage of asphalt mortar significantly affects the flexural strength of asphalt mixture. During the conditioning of dry-wet cycles, moisture concentration inside of the mixture increases monotonously. Moisture also diffuses to the interior in the drying stage, causing internal damage. With the increasing of dry-wet cycles, the mixture will crack at a small load level, and the propagation rate of the main crack is accelerated. [ABSTRACT FROM AUTHOR]

The asphalt mastic–aggregate interaction plays an important role in the overall properties of asphalt mixtures and their durability in service in flexible pavements. This paper aims to study the influence of the physico-chemical features of fillers and the rheological properties of asphalt mastics on the bonding behavior between asphalt and aggregate, and the interfacial deterioration mechanism when subjected to static water immersion and pressured water immersion. It was found that the filler type (limestone powder, basalt powder, and granite powder) had a certain influence on the complex modulus of asphalt mastics, and its pore volume and specific surface area had significant effects on the phase angles and permeability of asphalt mastics. The effect of water pressure can accelerate the deterioration of bond strength of the asphalt mastic–aggregate interface in the short term, indicating that the dynamic water pressure generated by the driving load promotes the water damage process in asphalt pavements. In comparison, the residual bond strength ratio of the granite–asphalt mastic aggregate was the highest, while its bond strength was lower than that of the interface between limestone–asphalt mastics and limestone aggregate. This demonstrated that a low asphalt mastic complex modulus and a high phase angle are helpful in improving the durability of asphalt mixtures subjected to static and pressured water immersion conditions. [ABSTRACT FROM AUTHOR]

Moisture-damaged buildings are a prominent issue in Finland, but with limited information on damage prevalence, degree of severity and risk factors. This paper analyses 14,996 Finnish detached and semidetached houses that have undergone a standardised moisture assessment of interior spaces and at-risk structures inside the building envelope. Confirmed damage (a binary indicator of damage presence) and a damage index (an ordinal indicator of severity) were calculated for each home and their association with different building and area characteristics estimated. Frequently damaged structures include pre-1950s log walls, walls contacting soil, wooden ground floors and false plinths. Around 15% of surveyed houses had risk structure damage, 19% had at least one confirmed damage anywhere in the house and 49% had either confirmed, likely or possible damage. The greatest risk factor for confirmed damage was house age (odds ratio = 1.48 (95% confidence interval (CI) = 1.45-1.51) for each decade since construction), with nearly half of all houses built pre-1939 damaged. Other risk factors explained a third of the effect of building age, and included log external walls, fibreboard roofs, absence of mechanical ventilation, detached properties and wind-driven rain precipitation. Results can support targeted remediation efforts, protect health and estimate exposure-response relationships for moisture damage. [ABSTRACT FROM AUTHOR]

This study aims to investigate the moisture and salt-erosion resistance of asphalt-calcined bauxite systems (ACBSs). The effects of the type of asphalt, aged asphalt, polymer modifiers, and grade of calcined bauxite on the moisture and salt-erosion resistance are evaluated by the pull-off strength and flaking rate of ACBSs after water immersion and neutral salt spray. The results show that a lower grade of asphalt is beneficial for the moisture resistance of an ACBS. Styrene-butadiene-styrene (SBS), antistripping agents, and polyphosphoric acid (PPA) improve moisture resistance, whereas rubber powder reduces it. Although the short-term thermal oxygen aging process can improve moisture resistance, high temperatures can result in the failure of the ammonia antistripping agent. The crystallization erosion from salt increases the moisture damage caused by water. The addition of modifiers and nonammonia antistripping agents can improve salt-erosion resistance; however, PPA has a weaker effect on salt-erosion resistance. Because the higher strength of the interface prevents moisture and salt erosion, an ACBS with a higher grade of calcined bauxite has higher moisture and salt-erosion resistance. [ABSTRACT FROM AUTHOR]

First, porous asphalt (PA) pavement possesses a lower strength and lifetime compared to typical dense-grade asphalt mixtures due to its large empty space structure. Second, PA pavements' fatigue life and durability are affected significantly by climate factors; the two most critical factors being aging conditions and moisture actions. Third, because of the environmental concerns connected with producing or repairing asphalt pavements using only virgin materials, studies have recommended reusing reclaimed asphalt pavement (RAP) materials. On the other hand, their use in road pavement is negative to the fatigue performance of asphalt pavements, especially PA. Therefore, modifying PA mixtures containing RAP to address the mentioned issues is necessary. Researchers have found that modifying asphalt mixes using nanotechnology is one of the more effective methods. The four-point bending beam fatigue test is one of the most dependable tests to assess the fatigue performance of asphalt mixtures, and evaluating the fatigue resistance of nano-modified PA mixes containing RAP under laboratory conditions by performing this test is essential. This study aims to investigate the fatigue behavior of different compounds of PA mixtures modified with nano zinc oxide (NZ) (0%, 2%, 4%, 6%, and 8%) containing various contents of RAP materials (0%, 25%, and 50%) under normal, long-term aging, and freeze–thaw (F–T) cycle conditions. Moreover, the self-healing capability of these PA samples was evaluated using this test by performing two 24-h recovery periods following the first and second loading. It can be inferred from the result that although adding RAP and inducting long-term aging and moisture-damaged conditions negatively influenced PA mixes' fatigue lives, incorporating NZ caused increases in these values by averages of 114%. Besides, results indicated that applied rest periods were observed to significantly impact PA specimens' self-healing capability, resulting in longer fatigue life for them. On average, conventional and NZ-modified PA mixes with/without RAP could recover up to 32 and 48% of their fatigue resistance in all conditions. [ABSTRACT FROM AUTHOR]

Freeze-thaw cycles in combination with long-term moisture exposure and traffic is a major threat to the performance of asphalt pavements. To enable characterisation and understanding of the damage process, this paper presents a new thermodynamics-based multiscale model of freeze-thaw damage in asphalt mixtures which also accounts for the damage due to moisture and traffic. The developed model consists of a microscale and a macroscale and is thereby able to account for the effect of the different microscale material components on the homogenous macroscale damage development. Additionally, the model is able to account for the acceleration of freeze-thaw damage which occurs when moisture infiltrates a damaged pavement with an increased effective air void content between freeze-thaw cycles. The novelty of the model lies in the ability to simulate the in-time acceleration of damage, the combined deteriorating effect of freeze-thaw cycles, moisture and traffic, as well as the coupling of the two scales to enable accurate predictions and understanding of the damage evolution. These features are demonstrated through a set of parametric examples which demonstrate the importance of including the effect of long-term moisture exposure and freeze-thaw cycles as well as the coupling between the different damage modes. [ABSTRACT FROM AUTHOR]

Moisture-induced stress tester (MIST) has been recently developed to simulate the dynamic stresses that cause moisture damage. In the current study, asphalt mixes containing 0%, 10%, 20%, 30%, and 40% RAP were subjected to 0, 1000, 2000, 3500, 5000, and 10,000 stress cycles of MIST and IDT strength test was conducted. The test results were analysed using the concepts of survival and atrophy to propose a damage mechanism and suggest an alternative to TSR. In unconditioned state, the control mix depicted a superior survival as compared to RAP mixes with <20% RAP, and an inferior survival as compared to RAP mixes with >20% RAP. Rate of atrophy indicated that the control mix has a higher instantaneous potential to fail (2.34 MPa in unconditioned state for control mix) than RAP mixes (0.90, 1.07, 1.13 and 1.21 MPa for 10%, 20%, 30%, and 40% RAP mix, respectively, in the unconditioned state). Stiffness and peak stress carrying capacity for control mix in unconditioned state was 310.87 and 1.47 MPa, respectively, which was higher than RAP mixes. For RAP mixes, MDRs based on rate of atrophy and TSR were > 80% thereby indicating that RAP has the potential to improve the moisture-induced damage resistivity of asphalt mixes. [ABSTRACT FROM AUTHOR]

Non-renewable resources such as natural stone and asphalt are in short supply. Recycling technology, with its lower cost, has been used as the primary approach to asphalt pavement maintenance engineering. The inclusion of reclaimed asphalt pavement materials in producing new asphalt pavements may increase the risk of cracking. The strength and toughness of the asphalt mixture can be reduced. In this study, Hamburg wheel tracking tests (HWTT) were performed on rejuvenated asphalt mixtures with distinct maintenance processes. Different kinds of fibers have been used as additives to reinforce the rejuvenated asphalt mixtures. The HWTT rutting curve was identified as having three stages, including the post-compaction stage, the creep stage, and the stripping stage. The three-stage rutting curve model was used to determine the intersection point between the creep stage and stripping stage. The other two feature points (i.e., the post-compaction point and the stripping inflection point) were redefined with a new calculation method. Then, the rutting effect and stripping effect were separated with these feature points. The performance and economic benefits of fiber-reinforced rejuvenated asphalt mixtures were investigated through grey correlation analysis under the three maintenance processes. The feature points of the HWTT curve and the cost of the corresponding maintenance process were selected as the impact factors. Finally, the optimal scheme was developed by analyzing the influence of each factor on both performance and economic benefits. [ABSTRACT FROM AUTHOR]

Modifiers such as fibers, fillers, natural and synthetic polymer extenders, oxidants and anti-oxidants, and anti-stripping agents are added to produce modified asphalt. However, polymers are the most widely utilized modifiers to enhance the function of asphalt mixtures. The objective of this research was to evaluate the mechanical properties and durability of epoxidized natural rubber (ENR)-modified asphalt mix under short- and long-term aging conditions. The physical and rheological characteristics of the base asphalt and ENR-modified asphalt (ENRMA) were tested. In order to evaluate the mechanical properties and durability of the modified mixtures, the resilient modulus of the ENR–asphalt mixtures under unaged, and short- and long-term aging conditions at various temperatures and frequencies was obtained. Furthermore, the resistance to moisture damage of asphalt mixtures was investigated. The findings showed that the stiffness of the ENR–asphalt mixes increased because of the mutual influence of short- and long-term aging on the mixes. In addition, ENR reduced the susceptibility to moisture damage. The stiffness of the mixes was influenced by the temperature and frequencies. By using mathematical modelling via the multivariable power least squares method, it was found that temperature was the dominant factor among all other factors. The results suggested that the durability of asphalt pavements is improved by using ENR. [ABSTRACT FROM AUTHOR]

Asphalt binder plays an important role in the overall resistance of asphalt mixture to the moisture damage induced by a dynamic pore water pressure environment. This study evaluates the moisture sensitivity of asphalt binder from the perspective of rheological behaviors using the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR) methods at high, medium, and low temperatures. The damage mechanism is further discussed quantitatively based on the Fourier transform infrared spectroscopy (FTIR) method. The results indicate that a longer conditioning duration is beneficial for asphalt binder to recover its adhesion at 60 °C in multiple stress creep recover (MSCR) tests, but the increasing pore water pressure magnitude of 60 psi held an opposite effect in this study. The asphalt binder's fatigue life at 20 °C in linear amplitude sweep (LAS) tests decreased obviously with conditioning duration and environmental severity, but the reducing rate gradually slowed down, while the groups of 50 psi—4000 cycles and 60 psi—4000 cycles held a comparable erosion effect. Both the stiffness and relaxation moduli at −12 °C in the BBR tests exhibited an obvious decreasing trend with conditioning duration and environmental severity. The erosion effect on the asphalt binder was gradually enhanced, but it also exhibited a slightly more viscous performance. Water conditioning induced several obvious characteristic peaks in the FTIR absorbance spectra of the asphalt binder. The functional group indexes presented a trend of non-monotonic change with conditioning duration and environmental severity, which made the asphalt binder show complicated rheological behaviors, such as non-monotonic variations in performance and the abnormal improving effect induced by dynamic pore water pressure conditioning. [ABSTRACT FROM AUTHOR]

Adhesiveness is a property that directly affects the service life of asphalt pavements. Over the years, different materials, research methods and tests have been used to investigate different adhesiveness aspects of materials. This paper investigated two asphalt binders, one with and one without amine-based anti-stripping agent, as well as two aggregate sources. The objective was to investigate the effects of rheology (stiffness and rutting) of the asphalt binder and adhesiveness of asphalt binders to different substrates on the resistance to moisture conditioning. The results indicated that moisture conditioning reduced the average stiffness of the binders by about 15% for both binders. The addition of amine-based anti-stripping agent reduced the stiffness of the neat binder by approximately 9%, and at 82°C the neat binder presented higher rutting resistance if compared to the modified binder using anti-stripping agent. The aggregate area within the HMAs in contact with asphalt binder did not show a good correlation with the pull-off tensile strength in the dry condition, but it presented good correlation after moisture conditioning. This suggests that adhesion force itself may not be greatly affected by the proper contact between aggregate and binder, but such contact does help preventing moisture damage in the interface. [ABSTRACT FROM AUTHOR]

Background and Aims: Moisture damage increases the risk for respiratory disorders in childhood. Our aim was to determine whether early age residential exposure to inspector‐observed moisture damage or mold is associated with different wheezing phenotypes later in childhood. Methods: Building inspections were performed by civil engineers, in a standardized manner, in the children's homes—mostly single family and row houses (N = 344)—in the first year of life. The children were followed up with repeated questionnaires until the age of 6 years and wheezing phenotypes—never/infrequent, transient, intermediate, late onset, and persistent—were defined using latent class analyses. The multinomial logistic regression model was used for statistical analysis. Results: A total of 63% (n = 218) had infrequent or no wheeze, 23% (n = 80) had transient and 9.6% (n = 21) had a persistent wheeze. Due to the low prevalence, results for intermediate (3.8%, n = 13) and late‐onset wheeze (3.5%, n = 12) were not further evaluated. Most consistent associations were observed with the persistent wheeze phenotype with an adjusted odds ratio (95% confidence intervals) 2.04 (0.67–6.18) for minor moisture damage with or without mold spots (present in 23.8% of homes) and 3.68 (1.04–13.05) for major damage or any moisture damage with visible mold in a child's main living areas (present in 13.4% of homes). Early‐age moisture damage or mold in the kitchen was associated with transient wheezing. Conclusion: At an early age, residential exposure to moisture damage or mold, can be dose‐dependently associated especially with persistent wheezing phenotype later in childhood. [ABSTRACT FROM AUTHOR]

Sustainability has recently gained a high profile in many felids. Construction, due to its huge demand to materials, is one of the important targets. More than 95% of roads are paved with hot mix asphalt (HMA). Production of HMA using virgin materials consumes a lot of energy and contributes to the emission of a considerably large volume of CO2. Therefore, the replacement of virgin materials with waste and extending material life is of considerable value. Half-warm bituminous emulsion mixture (HWBEM) is a cold bituminous emulsion mixture subjected to a moderate heating energy before the compaction process. This study aims to evaluate the extent of enhancement in HWBEM crack resistance using a low energy heating technique (i.e., microwave) where virgin fine aggregates within the mixture were replaced with waste crushed glass. In addition to the measurement of volumetric properties and mixture sensitivity to moisture damage, crack related tests of indirect tensile strength test (ITS), cracks resistance test (Ideal-CT test), fracture energy (Gf ), cracking resistance index (CRI) and toughness index (TI) were conducted to evaluate mixtures tensile strength. Test results showed that the procedure followed to prepare HWBEM containing waste crushed glass worked out and prevented cracking failure. It was concluded that adopting ITS is not sufficient to reflect all mixture behavior phases when resistance to the tensile cracking is the concern, as it depends on the peak load only. Other indices, such as CT-index, depend on more than one parameter and reflect a reasonably more realistic evaluation. [ABSTRACT FROM AUTHOR]

During the service period, asphalt materials are affected by various natural factors, including heat, ultraviolet light, oxygen and moisture, etc., resulting in the reduction of pavement performance, the increase of pavement distress and shortening of service life. This study aims to investigate the aging performance of asphalt under multiple aging conditions of heat, UV and aqueous solution. Thermal-oxygen aging, UV aging and hydrostatic erosion tests were carried out sequentially on asphalt. The rheological properties, chemical structure and element composition of asphalt were characterized before and after aging, and the effect mechanism of multiple conditions was discussed. The results show that the multiple conditions of heat and UV can increase the rutting resistance and weaken the cracking resistance of asphalt. However, the effect degree of UV decreases gradually with the deepening of aging degree. Additionally, the effect of water on the physicochemical properties is less than that of UV; however, water can increase the sensitivity of physicochemical properties to UV. In summary, this study explored the short-term cycling effect of heat, light and water on asphalt and provided an idea for simulation test of asphalt under multiple aging condition. [ABSTRACT FROM AUTHOR]

To enhance the moisture damage performance of hot mix asphalt (HMA), treating the aggregate surface with a suitable additive was a more convenient approach. In this research, two types of aggregate modifiers were used to study the effect of moisture damage on HMA. Three different aggregate sources were selected based on their abundance of use in HMA. To study the impact of these aggregate modifiers on moisture susceptibility of HMA, the indirect tensile strength test and indirect tensile modulus test were used as the performance tests. Moisture conditioning of specimens was carried out to simulate the effect of moisture on HMA. The prepared samples' tensile strength ratio (TSR) and stiffness modulus (Sm) results indicated a decrease in the strength of the HMA after moisture conditioning. After treating the aggregate surface with additives, an improvement was seen in dry and wet strength and stiffness. Moreover, an increasing trend was observed for both additives. The correlation between TSR and strength loss reveals a strong correlation (R2 = 0.7219). Also, the two additives indicate increased wettability of asphalt binder over aggregate, thus improving the adhesion between aggregate and asphalt binder. [ABSTRACT FROM AUTHOR]

Due to the depletion of conventional asphalt binder resources and price hiking, researchers are focused on introducing environmental friendly and sustainable materials as a replacement to the conventional binder. On the other hand, the production of a large quantity of sugarcane bagasse (SCB) leads to severe environmental problems. Therefore, effective utilisation of SCB bio-oil as a replacement to conventional binder can help in reducing the aforementioned problems. In this study, the conventional binder and mixture were modified at 5% and 10% SCB bio-oil. The rheological behaviour of the modified binder was analysed using conventional tests and dynamic shear rheometer. The performance of asphalt mixtures was then evaluated using dynamic modulus, cooper wheel tracker and four point beam fatigue test. The ability of modified mixtures against moisture damage was also assessed. The results indicate that the 10% SCB bio-oil sample possessed better fatigue resistance among all samples with insignificant effect on rutting resistance. Further, the SCB bio-oil negatively influenced moisture resistance of modified mixtures. So it can be concluded that SCB bio-oil can potentially be used to modify conventional binder and mixture. However, there is a need to improve the moisture resistance of SCB bio-oil modified binder. [ABSTRACT FROM AUTHOR]

As a by-product of steel making, the chemical composition of steel slag makes it prone to hydration, which may induce adverse impacts on steel slag asphalt mixture when exposed to moisture surroundings. In this study, a finite element model was developed to explore the effect of moisture damage considering steel slag hydration on the fracture properties of steel slag asphalt mixture. Then the numerical model was validated with experimental results. The effect of water on damage, horizontal stress distribution, as well as scalar stiffness degradation (SDEG) values were computationally analyzed. Moreover, some influencing factors such as the loading rate and aggregate morphology were considered. It is concluded that the presence of water would lead to the generation of hydration products, which results in reduced adhesion between fine aggregate matrix (FAM) and coarse aggregate. The unfavorable effect of water on strength is more significant at the FAM-coarse aggregate interface. A declined degree of 30.7% in the horizontal stress along the vertical centerline of the specimen is found by treating with water for 5 days. By changing the loading rate in the model, it could be found that immersion time has a significant impact on the proportion of damaged cohesive elements and damaged adhesive elements. While for the aggregate morphology, though the difference in aggregate morphology would lead to various degrees of stress concentration, the adverse of water has little impact on the stress concentration phenomenon. Based on mentioned above, the deterioration characteristics of water on steel slag asphalt mixture would provide guidance for the application of steel slag asphalt mixture in the future. • Fracture of steel slag asphalt mixture subjected to moisture damage was analyzed. • The adverse impact of water on interfacial strength is more significant. • The generation of hydration products would lead to a decline in adhesion. • The presence of water would lead to a rise in the proportion of cohesive damage. [ABSTRACT FROM AUTHOR]

This paper comprehensively reviews present research on the potential for repurposing primary categories of waste plastics. These include Polyethylene Terephthalate (PETE), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS), and other variants such as Acrylonitrile Butadiene Styrene (ABS), Ethylene Vinyl Acetate (EVA), Polycarbonate (PC), and Polyurethane (PU). The focus is on their use in the construction of bituminous mixes via the dry process method. This method incorporates plastic waste into bituminous mixes by modifying the mixture or replacing aggregates. This practice has consistently demonstrated improvements in pavement performance, including increased stiffness, resistance to rutting, and fatigue. When bituminous mixtures are modified with the mixture modifying approach using low melting point plastics such as LDPE, HDPE, and LLDPE, a significant reduction in OBC is observed. Furthermore, the mixture modification approach has demonstrated higher resistance to moisture damage, rutting, and fatigue damage than the aggregate replacement approach. The potential benefits of using plastics in the bituminous pavement are substantial. This includes a reduction in the amount of waste sent to landfills, a decrease in reliance on finite natural resources, and the expansion of options for constructing bituminous pavements. Economic analyses have shown that using waste plastics can reduce pavement construction costs by 10%, with a minimal probability of leaching. Despite a multifold increase in the emission of greenhouse gases, an overall reduction in environmental impact was observed from the life cycle assessment study. However, the use of PVC and dark-colored plastics is not recommended. Field studies conducted on roads constructed with waste plastic-modified bituminous pavements showed notable improvements. Most of these pavements exhibited higher Pavement Condition Index (PCI) values and lower International Roughness Index (IRI) values than conventional pavements. These findings underscore the superior riding quality and reduced deterioration associated with waste plastic incorporation. Moreover, in-plant production processes, plants require minimal modifications, as existing equipment used for feeding fibers is well-suited for adding plastics into the mixture. In conclusion, further research is essential to fully understand the impact of different types of plastics on pavement performance and to evaluate this process's potential environmental and economic implications. This paper seeks to bridge the gap in the literature by reviewing and discussing the performance of such mixes and constructed pavements in laboratory and field situations. ● The impact of different plastics on mechanical performance of bituminous mix has been reviewed. ● Plastics at OPC improves bituminous mixture's mechanical performance. ● Long term field performance studies have been reviewed. ● Pavements containing waste plastics shows better riding quality and less deterioration. ● Future studies should more focus on environmental assessment. [ABSTRACT FROM AUTHOR]

One of the major problems caused by the construction and demolition of buildings is the environmental pollution due to the disposal of the large volume of generated waste materials. In addition to the protection of environment, the recycling and reusing of the waste materials are an economical measure. In this research, the viability of using the recycled brick powder as a partial or full replacement of mineral filler in asphalt concrete has been investigated. The primary natural siliceous aggregate filler, as control filler, has been replaced in different percentages, with the secondary recycled brick powder, and the mixtures have been evaluated in terms of, Marshal Stability, flow, indirect tensile strength, moisture damage and volumetric characteristics. The results show that, the Marshal Stability increases and the flow decreases with increasing the brick powder content in the mixture. The results show that full replacement of the natural filler with brick powder results in the highest resistance against permanent deformation and indirect tensile strength. It is also shown that the mixtures containing brick powder are more resistant against moisture damage than the control mixture. The replacement of the mineral filler with the brick powder does not significantly affect the volumetric properties of the mixture. [ABSTRACT FROM AUTHOR]

The aim of the current research was to evaluate, model, and predict the water sensitivity of a mixture modified by nano TiO2 using the artificial neural network (ANN) and multiple linear regression (MLR) models. Also, the effect of nano TiO2 on the performance of asphalt binder was evaluated. The indirect tensile strength (ITS) test was used to measure the performance of different mixtures through ITS, tensile strength ratio (TSR), and fracture energy ratio (FER) parameters. To measure the effect of nano TiO2 on the performance of mixtures, five percentages of nano TiO2 (0%, 2%, 4%, 6%, and 8%) were added to the asphalt binder. In the current research, steel slag was used as a substitution of coarse aggregate not only to use waste materials but also to omit environmental emissions. Results revealed that using nano TiO2 decreased the penetration grade and ductility and increased the softening point of asphalt binders. Results revealed that addition of nano TiO2 decreased the temperature susceptibility of binder. Regarding the viscosity test results, applying nano TiO2 increased the viscosity of control asphalt binder. Moreover, the viscosity values of asphalt binders increased as the nano TiO2 percentages raised. The viscosity-temperature susceptibility (VTS) test results showed that TiO2 reduced the VTS of the control asphalt binder and lower-VTS asphalt binders had a better resistance. The results also indicated that with substitution of aggregate ITS, TSR, fracture energy (FE), and FER of asphalt mixtures reduced. Based on results, addition of nano TiO2 increased the ITS and FE of mixtures in wet and dry condition and also the TSR and FER of mixtures increased. Moreover, based on the results, by assessing and comparing the experimental and predicted values, an appropriate accuracy in the estimation of values by the ANN and MLR models was determined. Also, the ANN model had better accuracy than MLR in predicting results in all cases. [ABSTRACT FROM AUTHOR]

The mechanical performance of asphalt mixtures with high air void content – like Permeable Friction Courses (PFC) – is significantly affected by climate-related processes. Previous studies have demonstrated that ravelling (i.e. the loss of aggregates from the surface of the PFC) is related to the quality of the stone-on-stone contacts within the microstructure of these mixtures. Since the material located at these contacts is asphalt mortar, the durability of the mixtures strongly depends on the mechanical properties of this phase. This paper evaluates, for the first time, the coupled effects of ageing and moisture on the mechanical and fracture properties of the asphalt mortar of a typical PFC. The climatic conditioning processes included short and long-term ageing and dry-wet-dry moisture vapour cycles. The linear viscoelastic and fracture properties of the PFC mortar specimens were characterised using Dynamic Mechanical Analyser (DMA) and Semi-Circular Bending (SCB) tests. The results showed that ageing impacted the dynamic modulus of the mortar, while moisture had a negligible effect on this property. Also, the coupled effects of long-term ageing and moisture cycles reduced the fracture energy and other fracture parameters of the mortar between 2 and 10 times with respect to the short-term ageing condition in dry state. [ABSTRACT FROM AUTHOR]

This paper reports moisture damage analyses of recycled asphalt pavement (RAP) aggregate–enriched bituminous concrete (BC). This investigation determines the effective RAP aggregate percentage for producing a moisture-resistive 19-mm nominal-sized aggregate–enriched BC mix. To execute such a study, virgin aggregate (VA) has been replaced by 0%, 10%, 20%, 30%, 40%, 50%, 60%, 75%, and 100% RAP aggregate a on random selection basis at laboratory scale to explore the effect of each sample in BC mix. After calculating the optimum bitumen contents (OBCs) for the aforementioned BC mixes via the Marshall mix design, a moisture damage analysis was conducted using a modified Marshall immersion test. Experimental results show that 50% RAP aggregate–enriched BC mix may be used in low-volume roads in colder regions containing 0.07% less OBC than conventional BC mix. That mix may have 83.71% moisture damage resistive potency up to a 7-day immersion period. This improvement is due to the presence of a sufficient amount of carbonyl compound in the binder. Quantifying such compounds in the bitumen has been done by Fourier transform infrared analysis of the bitumen, as reported in the literature (Karmakar et al. 2018; Karmakar and Roy 2021). The moisture resistive potency of the 50% RAP aggregate–enriched BC mixes has also been confirmed by the indirect tensile strength (ITS) test, energy loss ratio test, and boiling water test. The results of those tests revealed that the presence of carbonyl compound in the binder of 50% RAP–enriched BC mix elevates the mix's flexural resistance against moisture damage for a 4-day immersion period due to having 1.15% more coating ability than a virgin binder. [ABSTRACT FROM AUTHOR]

Asphalt binder plays a vital role in the entire resistance to moisture damage for asphalt mixture. Comparing with static water immersion and freeze-thaw, the water environment of dynamic pore water pressure induced by moving vehicle loads exhibits a different damage mechanism on asphalt pavement. This study evaluated moisture sensitivity of a base asphalt binder using multi-scale experimental methods, which included bending beam rheometer (BBR) test, surface free energy (SFE) method, and Fourier transform infrared spectroscopy (FTIR) test. The results showed that both the BBR retained stiffness ratio and the water stability indexes calculated by SFE parameters declined with the conditioning duration in dynamic water environment. The water erosion effect of long-term conditioning in dynamic water environment on asphalt binder was harsher than static water immersion and almost equal to and even harsher than freeze-thaw. The FTIR spectrums showed that all water conditioning environments could cause fluctuations of transmission rate in several wavenumber ranges, while dynamic water environment showed more significant influences. The erosion effects induced by water environments of static water immersion, freeze-thaw, and dynamic pore water pressure on asphalt binder showed basically consistent ranking and regulars. However, apparent differences of the influential extents induced by water environments on functional groups and chemical bonds of asphalt binder emerged around wavenumbers of 3425, 1460, and 1376 cm- 1in the FTIR spectrums. [ABSTRACT FROM AUTHOR]

In this paper, data from the PURWheel-G2 , a rubber tire wheel tracker, was utilized alongside several techniques to better understand isolation of the effects of moisture on asphalt rutting. Techniques commonly used to interpret wheel tracking data, particularly to evaluate moisture damage, were summarized and used to evaluate over 150 PURWheel-G2 tests where wet and dry pairs of tests were conducted to directly isolate the effect of moisture on rutting. Among all the available wheel tracking analysis techniques and models for moisture evaluation, there lacks a consensus approach, and available approaches vary widely highlighting the need for a standard test method. The rubber tire wheel tracker presented in this paper aims to take a step towards developing test protocols to isolate moisture damage. The ability to measure the effects of moisture on rutting is a feature that other existing wheel tracking methods cannot do on their own. • Rubber-tire wheel tracker tests were evaluated to isolate the effects of moisture. • Over 150 PURWheel-G2 tests in wet and dry conditions were conducted. • There is no consensus on how to analyze wheel tracking data for moisture evaluation.. [ABSTRACT FROM AUTHOR]

Moisture damage is one of the major concerns of transportation agencies. Improper coating of asphalt binder over aggregate surface provides easy access at the aggregate-binder interface for moisture induced adhesive failure. Due to sheer size, there is a large difference in specific surface area of coarse and fine aggregates. During conventional mixing process, this difference in area leads to non-homogeneous distribution of binder. Fines receive thicker binder thickness and more absorption compare to coarse aggregates. Also, filler particles inhibit the binder from penetrating into micro-pores of coarse aggregate and devoid binder the opportunity to penetrate its surface deeply. Aggregate-binder interface is significantly influenced by the sequence in which aggregate and bitumen are mixed, aggregate type and moisture conditioning. The current practice in industry is to mix the entire proportion of aggregates together with bitumen in one-phase. In this study, a two-phase mixing sequence is proposed in which initially half of the binder content is premixed with coarse aggregates, followed by adding fines and remaining binder in the second step. The paper presents a novel study to evaluate the effect of two phase mixing on viscoelastic properties of dense asphalt mix. Further, effect of the proposed two-phase mixing on moisture sensitivity has been investigated using mechanical performance test. For this, conditioned dynamic modulus test was performed after 0, 1, 3 and 6 freeze-thaw cycles and then compared with tensile strength ratio test. Furthermore, the influence of moisture damage on aggregate-bitumen interface was studied using bond strength test. Granitic aggregates had higher silica content and were more moisture susceptible as compared to basalt. The interfacial failure mode in both the aggregates were cohesive in unconditioned specimens, which on conditioning drifted from cohesive to adhesive. For all the aggregates, two-phase mixing was found to significantly improve moisture damage resistance of mixes compared to the conventional one-phase mixing. [Display omitted] • Two-phase mixing process is proposed to improve moisture damage resistance of HMA. • Effect of moisture on modulus and TSR is studied at 0,1,3 and 6 FT cycles. • Two-phase mixing produced better crack resistance before and after conditioning. • Two-phase mixes had higher dynamic modulus and ITS compared to conventional mixes. • Aggregate-binder interface is significantly influenced by mixing sequence, aggregate type and moisture conditioning. [ABSTRACT FROM AUTHOR]

Moisture damage is a main factor degrading the bonding performance between asphalt binder and aggregate, playing adverse effects on the integrity of pavements, and thus reducing their serviceability substantially. The asphalt pavement is susceptible to moisture damage, exhibiting weakened durability and accelerated distress in many other formations with lower service life. In this study, moisture damage was reflected in the immersion method of Marshall test, and the deterioration potential of moisture damage on the fracture behaviors of asphalt mixture was investigated through multi-scale analysis. Pull-off tests were carried out to characterize the bonding performance between asphalt binder and aggregate considering the influence of moisture erosion, and the adhesion and cohesion results were adopted as the key mechanical parameters for the subsequent numerical analysis. Semi-circular bending (SCB) tests were conducted for the specimens with or without water immersion conditioning, and the fracture parameters, including the critical strain energy release rate (J-integral), Flexibility Index (FI), Crack Resistance Index (CRI), and Balanced Cracking Index (BCI), were obtained to provide insights into the fracture performance of the asphalt mixture. Furthermore, the mechanism of moisture affecting the fracture behavior of asphalt mixtures in meso-scale was explored through numerical analysis based on finite element modeling (FEM). A virtual SCB specimen integrated with two cohesive zone models (CZM) describing the failure of asphalt mortar and the loss of adhesion between asphalt binder and aggregate was established. The results from pull-off tests indicated that water immersion could enlarge the adhesive failure area and subsequently decrease the bonding strength between binder and aggregate. However, moisture damage had a limited effect on cohesive failure performance. Results from SCB tests showed that immersion could significantly increase the moisture damage potential and the crack development speed, weaken the fracture resistance, and reduce the flexibility of the asphalt mixture. The numerical analysis method proposed in the study was effective to interpret the effect of moisture damage on the fracture behaviors of the asphalt mixture. It was found that moisture damage led to more pronounced internal damage, and more failures at the interface of binder-aggregate were observed due to the deterioration effect of moisture erosion on the adhesion. According to the fracture development under dry and wet conditioning, the asphalt mixture would crack earlier after encountering moisture damage. The research method combining laboratory tests and numerical simulations demonstrated more comprehensively the impact of moisture damage on the fracture performance of asphalt mixture from a macro to meso perspective. • The fracture performance of asphalt mixtures was measured under the influence of moisture damage. • The cohesive failure and adhesive failure were studied under different asphalt film thicknesses. • The mesoscopic damage caused by moisture damage was measured using the FEM. [ABSTRACT FROM AUTHOR]

The current research work, examines efficacy of asphalt mixes prepared with varied proportions of nano SiO 2 and nano Al 2 O 3. The study assessed the performance of modified asphalt mixes through Marshall stability, flow, indirect tensile strength, resilient modulus, Dynamic modulus, Flow number, and 4-Point bending tests. Elevated nanomaterial dosages notably enhanced high and intermediate temperature performance, nearly tripling rutting resistance, and augmenting fatigue resistance by approximately 130%. Elevated tensile strength ratios confirmed improved moisture resilience. The statistical analysis showed that nanomaterials had a significant influence on properties of asphalt mixes. Overall, diverse test approaches underscored the potential of nanomaterials in enhancing asphalt mix properties, promising durable and long-lasting pavements. • Investigate the use of nano SiO 2 and nano Al 2 O 3 , as modifiers for asphalt mixes. • The asphalt mixes were prepared with varying proportions of the two nanomaterials. • Incorporating nanomaterials improved rutting and fatigue properties of the mixes. • Nanomodified mixes exhibited higher stiffness and improved moisture resistance. • Asphalt mixes consisting of 2% nano Al 2 O 3 , demonstrated the best performance. [ABSTRACT FROM AUTHOR]

The present study investigates the mechanism by which lignin enhances the moisture resistance of asphalt materials, employing a combination of atomic force microscopy (AFM) and molecular simulations. The research aims to understand the changes in surface morphology and adhesion properties of asphalt upon immersion, and elucidate the role of lignin modification in mitigating the reduction of adhesive forces. AFM measurements reveal that lignin-modified asphalt exhibits higher adhesion force after moisture damage, possibly attributable to less nanostructures on the surface of lignin modified asphalt. Molecular dynamics simulations are employed to study the binding energies between lignin and different asphalt constituents. The results demonstrate that lignin exhibits the strongest binding affinity with asphaltene molecules, and also displays significant binding affinity with a specific saturated molecule. Furthermore, diffusion of water molecules on asphalt surfaces is investigated, revealing that lignin-modified asphalt exhibits lower water molecule diffusion coefficients and reduced binding energies. Finally, a spherical water molecule model is employed to analyze the wetting behavior on lignin-modified asphalt surfaces, illustrating the dual mechanism of lignin molecules resisting water molecules and inhibiting the binding of polar molecules within asphalt to water molecules. The findings of this research provide insights into the enhancement of moisture resistance in asphalt materials through lignin modification. The combination of AFM and molecular simulations offers a comprehensive understanding of the morphological and adhesive changes at the nanoscale, as well as the fundamental molecular interactions involved. The results contribute to the development of strategies for designing and engineering asphalt materials with improved resistance to moisture damage. [ABSTRACT FROM AUTHOR]

Moisture-induced damage of asphalt pavements constitutes a primary distress. To quantify the extent of moisture-induced damage efficiently, a moisture-induced stress tester (MIST) was developed. This study adopts varying stress cycles of MIST to condition the asphalt mixes without and with reclaimed asphalt pavement (RAP) to ascertain their moisture-induced damage resistivity. Hence, the control mix (0% RAP) and mixes containing 10%, 20%, 30%, and 40% RAP by weight were prepared and conditioned using 0, 1,000, 2,000, 3,500, 5,000, and 10,000 stress cycles of MIST. Thereafter, an indirect tensile (IDT) strength test was conducted on the prepared mixes. Using analytical approaches, the biaxial state of stress was defined to compute the static (ES,H) and average modulus (ES,A). Increasing stress cycles of MIST decreased the stiffness of control and RAP mixes. The compressive stress–strain curve (SSC) was plotted and utilized to compute the linearity and toughness index (TI) of control and RAP mixes. Increasing stress cycles of MIST were observed to increase the ductility of control and RAP mixes, whereas prepeak linearity was observed to reduce it. The TI increased with the increase in stress cycles of MIST. New moisture damage ratios (MDRs) were computed by utilizing ES,H and ES,A and compared with the commonly adopted tensile strength ratio (TSR). Based on such MDRs, it was concluded that RAP improves the moisture-induced damage resistivity of asphalt mixes. Statistical analysis indicated that both ES,H and ES,A have the potential to be good indicators of moisture-induced damage of control and RAP mixes. [ABSTRACT FROM AUTHOR]

This paper proposes the use of phosphorous methyl compound (PMC) as a modifier in asphalt binder to improve its viscoelastic properties. Dosage of PMC was optimised using conventional and other rheological tests. Fourier transform infrared spectroscopy analysis was also conducted to assess the functional groups between asphalt binder and the PMC. Asphalt binder and mixtures were prepared and tested using performance testing to verify the effect of the PMC on their performance. Based on experimental results, an optimum dosage of 0.75% PMC by weight of asphalt binder is recommended for improvement in asphalt properties. Upon the inclusion of 0.75% dosage by weight of the PMC, the asphalt binder with performance 58 grade has performed equivalent to that of superpave PG 76 grade asphalt binder. An addition of about 0.75% PMC by weight of asphalt binder improved rutting resistance, dynamic modulus and resistance to moisture damage by around 30%. [ABSTRACT FROM AUTHOR]

Cold patch asphalt is more preferable in pavement construction compared to hot mix asphalt from the perspective of environmental conservation. However, the cold patch asphalt mixture is prone to moisture damage for production at lower temperatures and the presence of a diluent. The objective of this paper is to evaluate the moisture induce damage potential of cold patch asphalt mixture based on surface free energy theory. Three kinds of cold patch asphalts were synthesized by base asphalt, abietic resin, diesel, and anti-stripping agent, while the aggregates consisted of limestone and basalt. The surface free energy components of cold patch asphalt and aggregates were measured using the high-precision automatic Tensiometer System and Gravimetric Sorption Analyzer, respectively. The analytical computation to assess cohesive bond energy, wettability, adhesion bond energy, and energy ratio was obtained after surface free energy calculations. The results showed that the mixture of additives decreased the surface free energy of cold patch asphalt. Moreover, diesel can increase the surface free energy of pure asphalt. However, the abietic resin and anti-stripping agent have an adverse effect. Therefore, it can be concluded that the cold patch asphalt synthesized in this study has better resistance to water damage ability than base asphalt. More cold patch asphalt and aggregates are strongly suggested to validate the findings of this research. [ABSTRACT FROM AUTHOR]

In recent years, the use of reclaimed asphalt pavement (RAP) has gained much attention and is widely accepted. However, the rejuvenating agents which are usually used to reduce the rigidity of the aged asphalt are subjected to diverse climate circumstances. The present work used maltene as a rejuvenator to investigate several measurements regarding stripping failure. The evaluation of wettability and work of adhesion (WA) was assessed using the sessile drop method. Meanwhile, asphalt and asphalt-water aggregate systems were tested for acid and water resistance using chemical and water immersion tests. Next, atomic force microscopy (AFM) was used to evaluate the changes in the microstructures of the asphalt binders. The experimental results revealed that the ideal percentages of maltene which should be added to 30% and 50% aged asphalt were 8% and 16%, respectively. Meanwhile, the wettability, WA and resistance to stripping differed depending on the percentage of aged asphalt in the blend. However, the inclusion of maltene has improved samples containing high percentages of aged asphalt. On the other hand, the resistance to boiling water containing acid decreased slightly with the addition of maltene. Nevertheless, all the rejuvenated samples exhibited better results than virgin asphalt. Moreover, the AFM results were in line with the observations, suggesting the suitability of maltene for the functional application of pavement. [ABSTRACT FROM AUTHOR]

Cement Grouted Bituminous mix (CGBM) mix is a semi-flexible pavement type that essentially is an open-graded bituminous mix grouted with cement mortar comprising the advantages of both flexible and rigid pavements. CGBM is not popular and widely adopted in India so far may be due to a lack of available performance studies imparting knowledge. Therefore, an attempt has been made in this study to prepare grouting material and develop the mix design consideration first. Further, CGBM characteristics as an alternative recarpeting and/or wearing course material in the Indian scenario based on laboratory and field evaluation in comparison with bituminous concrete mix that is conventional wearing course is explored. In this regard, a trial stretch of CGBM is constructed in the urban area, and field performance is ensured with the laboratory results. Test results reveal that the CGBM mix possesses higher Marshall stability, compressive strength, tensile strength, resilient modulus, better resistance against the moisture damage and oil spillage condition, and less temperature susceptible than the conventional bituminous concrete mix. This case study of CGBM overlay is substantially increasing the remaining service life of the pavement in terms of fatigue and rutting life. [ABSTRACT FROM AUTHOR]

In this study, it has been attempted to use thermodynamics theories and the surface free energy (SFE) method to evaluate the effect of anti-stripping additives on the asphalt binder cohesion and asphalt binder–aggregate adhesion under dry and wet conditions. Two types of aggregate, granite and limestone, AC 60–70 and two additives (a polar copolymer and an ethylene copolymer with mineral asphalt binder) used are among the materials used in this study. The results indicate that the use of both types of polymer has increased the cohesion of the asphalt binder and reduced failure in the asphalt binder film. The results show that the polar copolymer increases the basic components and decreases acidic component of the asphalt binder surface free energy that increases the adhesion with acidic aggregates that are susceptible to moisture-induced damage. Ethylene copolymer material also increased the asphalt binder surface free energy that strengthens the non-polar asphalt binder–aggregate bonds. Both polymer materials have reduced the separated free energy and increased the adhesion free energy that reduces the desire for the stripping process in the asphalt mixture. The results of mechanical tests also show that the use of polymeric additives has improved the asphalt mixtures strength against moisture-induced damage. [ABSTRACT FROM AUTHOR]

Moisture damage occurs due to loss of cohesion and/or adhesion, which results in loss of stiffness and strength. Currently, the surface free energy (SFE) approach is used to calculate mixture performance in terms of various SFE parameters to assess moisture susceptibility of various newly developed binders. In the present study, the concept of SFE is used to evaluate the moisture-induced damage potential of newly modified bitumen using high-density polyethylene (HDPE) pyro-oil. For this purpose, parameters of SFE considered are work of adhesion, work of cohesion, wettability, and energy ratio (ER). HDPE pyro-oil was obtained from pyrolysis process at 750°C. For determination of surface tension properties of base and modified bitumen, this study used glycerol, formamide, and distilled water as probe liquid, and a sessile drop method was adopted to measure the static contact angle. The aggregates considered in this study were basalt, gravel, and limestone. Dispersive and polar components of aggregates were directly taken from the literature. In contrast, for base bitumen (VG30) and pyro-oil–modified bitumen (POMB), these components were determined using van Oss–Chaudhury–Good theory. Along with this, the variation in contact angle, SFE components and surface tension parameter of base and modified bitumen were studied for different time of ageing (0, 45, 85, and 150 min) using rolling thin film oven (RTFO) as per guidelines of Superpave. The investigation concludes that, for the parameters under study, the analysis of data does not show any regular pattern. Work of adhesion decreases whereas work of cohesion increases with ageing resulting in increased moisture susceptibility for pyro-oil–modified bitumen. Further, the results showed that pyro-oil was effective in enhancing the surface tension parameter as compared to the base binder for different ageing conditions. Based on the results of energy ratio, it is concluded that a combination of the binder with basalt gives higher resistance to moisture damage than limestone and gravel. [ABSTRACT FROM AUTHOR]

Moisture-induced damage in asphalt concrete is a major concern to the transportation agencies. Existing moisture sensitivity tests are mostly conducted at the macro- or micro-level and focused on the qualitative measurements only. In this study, the atomic force microscopy (AFM) technology is utilized to investigate moisture susceptibility of asphalt binders through the estimation of nano-level dissipated energy (DE). For the comparison of the AFM test results, two macro-level tests data are also used. Asphalt binders used in this study include a Performance Grade (PG) base binder (PG 64-22) along with its modified counterparts, which are blended with polyphosphoric acid (PPA), styrene–butadiene-styrene (SBS), and SBS plus PPA. Additionally, the effects of three different types of liquid anti-stripping agents (LAA) were investigated. The test specimens of these binder samples were prepared under dry and wet conditions, and their DE values were estimated from AFM tests. Results showed that the base binder and the PPA-modified binder had higher DE values than the SBS- or the SBS + PPA-modified binders. Among all the LAAs, Evotherm showed better resistance to moisture damage than the other ones. Findings of this study are expected to help highway agencies to quantify the moisture resistance of asphalt materials precisely. [ABSTRACT FROM AUTHOR]

The field cores taken from the asphalt pavement were soaked for long term after vacuum saturation. The indirect tensile strength, the failure stiffness modulus and the tensile strength ratio (TSR) of samples are determined by the indirect tensile test with or without the freeze-thaw cycles. The indirect tensile test and unconfined compressive strength test are devised to measure the unconfined compressive strength and cohesion of specimens immersed in the water for different period. Moreover, the sensitivities of each mechanical index to evaluate the moisture damage of long-term immersed asphalt mixture were compared. The test results indicate that the indirect tensile strength, failure stiffness modulus, TSR, compressive strength and cohesion of asphalt mixtures were all decreased due to the long-term action of water. After immersion for 540 days, the loss rate of unconfined compressive strength was the highest, reaching 62.6%, followed by cohesion, whose loss rate was 50.6%, indicating that under the condition of high temperature 60°C, the longer the saturation lasts, the more obviously the compressive strength and cohesion change, which are all sensitive to moisture damage. Under low temperature conditions, compared with the indirect tensile strength and TSR, the loss rate of failure stiffness modulus is 36.8%, representing its moderate sensibility to moisture damage. At early stage of 6 months, these mechanical indexes declined rapidly, and then gradually became slower. The free water remaining in the samples continuously infiltrated into the interface between asphalt film and aggregates, resulting in a decrease in the adhesion and the contact angle between them as well as a decrease in the cohesion. [ABSTRACT FROM AUTHOR]