Rutting Resistance Of Mixtures Research Articles

Resurface of rubber modified asphalt mixture with stress absorbing membrane interlayer: From laboratory to field application

The increasing concern over tire pollution, exacerbated by the improper disposal of waste tires, serves as the backdrop for this research, which aims to explore the efficacy of incorporating ground tire rubber (GTR) into asphalt mixtures enhanced with a stress-absorbing membrane interlayer (SAMI). In this study, three variations of Hot Mix Asphalt (HMA) were evaluated: a conventional mix, a rubber-modified asphalt mixture (RMA), and a trans-polyoctenamer rubber (TOR) modified asphalt mixture in the laboratory. The assessment focused on the high and low-temperature performance of the asphalt mix and binder. Key findings from the laboratory tests indicate that the integration of a SAMI layer and GTR as additives markedly boosts the crack resistance of the asphalt mixture. Despite a reduction in fracture energy across all three HMA types following long-term aging, the GTR-modified HMA maintained superior fracture energy relative to the conventional mix. Initially, the inclusion of GTR adversely affected the mixture's rutting resistance. However, after undergoing long-term aging, both the conventional and GTR-modified HMAs exhibited exceptional rutting and moisture damage resistance. Field noise assessments further demonstrated that GTR-enhanced pavements produced noise levels approximately 2 dB lower than those of standard asphalt pavements. Additionally, pavements lacking a SAMI layer manifested low-severity cracking, with an average cracking frequency occurring every 2 ∼ 6 m, whereas pavements equipped with a SAMI layer exhibited no cracking following two winter seasons. The rubber asphalt overlay may increase the leaching of 6PPD-quinone, but the SAMI layer helps reduce tire wear particle generation by preventing road cracking. Rubber asphalt overlay leaching tests resulted in 6PPD-quinone concentrations lower than currently available toxicity data (LC50 for Coho Salmon, 0.095 ug/L). In conclusion, the utilization of dry-processed rubber asphalt mixes alongside a SAMI layer in pavement construction not only has the potential to extend the service life of pavements but also contributes to the production of quieter road surfaces. This study underscores the environmental and functional benefits of incorporating rubber modifications into asphalt pavements, presenting a viable strategy for mitigating tire pollution through the reuse of waste tires in infrastructure.

Experimental investigation of performance properties of asphalt binder and stone matrix asphalt mixture using waste material and warm mix additive

Many distresses occur in the pavement due to the increase in traffic and changes in weather conditions through the year (hot to cold). Asphalt binder modification is the best way to control these stresses. On the other hand, utilization of warm mix asphalt additives has significant environmental benefits. This research investigates the influence of simultaneous usage of two waste material (ground tire rubber (5%, 10% 15%, and 20% by weight of asphalt binder) and natural bitumen (10%, 20%, 30%, and 40% by weight of asphalt binder)) on performance behavior of asphalt binders and mixtures containing warm mix asphalt additive. Performance behavior of binders and mixtures were evaluated by several tests such as; conventional asphalt binder tests, linear Amplitude Sweep (LAS), Multiple Stress Creep Recovery (MSCR), Bending Beam Rheometer (BBR), Dynamic Shear Rheometer (DSR), storage stability, resilient modulus, indirect tensile strength, dynamic creep, hamburg wheel track, and four point beam fatigue (FPB) tests. The statistical analysis was performed to investigate the additives have significant effect or not. Results revealed that fatigue and rutting performance of samples were improved by combination of waste materials. Addition of waste natural bitumen led to decreases the low-temperature behavior of asphalt binder, while addition of waste ground tire rubber improves the resistance against low-temperature cracking. Addition of natural bitumen up to 10% has positive impact on storage stability of binder and by adding more content of additive, phase separation occurred. Warm mix additives improve the fatigue and rutting resistance of mixtures containing waste materials. Adding 20% CR to 30% Gilsonite -modified binder causes an enhanced the high temperature characteristics of about 34%. Based on outcomes, waste ground tire rubber enhances the fatigue resistance of mixtures containing natural bitumen. In general, utilization of waste materials in combination with warm mix additives improve the performance properties of asphalt binder and mixture. Mr of mixtures, containing 40% Gilsonite, was 52% greater compared to base mixture. Nonetheless, 30% Gilsonite as well as 5% CR had Mr values nearly 44% higher compared to base mixture. Also, based on statistical analysis, addition of mentioned additives has significant effect on improving the performance of specimens.

Performance Evaluation of SMA Mixtures Modified by Nanoclay

Abstract Fatigue cracking and permanent deformation are two major distresses that occur in asphalt pavements. Several studies in that past have indicated that utilization of nanomaterials, especially nanoclays, has a significant influence on enhancing the performance of pavement. Therefore, the aim of the current paper is to evaluate the influence of montmorillonite nanoclay on intermediate and high-temperature performance of an original binder and mixture modified by styrene-butadiene-styrene (SBS). Different percentages of nanoclay were added to the original binder (1, 2, 3 and 4 % by the weight of the binder). The fatigue and rutting behavior of binders were evaluated through linear amplitude sweep and multiple stress creep recovery (MSCR) tests. To investigate the performance of mixtures, several mixture tests were implemented, such as static and dynamic creep, wheel track, and four-point beam fatigue tests. The results of the MSCR test revealed that the addition of nanoclay and polymer improves the rutting resistance of the binder, and among modified binders, binder modified with 4 % nanoclay and 5 % SBS has the lowest Jnr and highest percent recovery value. Based on the mixture performance tests results, by the addition of nanoclay, the fatigue and rutting resistance of mixtures increased up to 3 %, and by the addition of more nanoclay, a decreasing trend was observed.

Laboratory investigation on warm mix asphalt incorporating organo-silane additive

Warm mix asphalt (WMA) was developed to reduce asphalt production temperatures and energy consumption. Production of toxic gas emissions can be reduced considerably. However, lowered production temperature results in the presence of trapped moisture in the aggregates that could lead to stripping and subsequently moisture susceptibility problems, and which can be mitigated by using additives. Asphalt mixtures incorporating such additive must exhibit at least similar performance to conventional hot mix asphalts (HMA) which produce at higher temperatures. This paper evaluates the engineering properties and moisture susceptibility of asphalt mixtures incorporating Organo-Silane additive for use as WMA and anti-stripping agent. WMA samples were compacted at 125 °C and 115 °C and their performance were compared with control HMA specimens. The asphalt mixtures were prepared using similar aggregate gradation and binder types. Mixture workability was quantified in terms of the Compaction Energy Index (CEI) that was measured by integrating the area under the densification curve between gyration 8 and 92% theoretical maximum density. Lower CEI implies a more workable mixture. The CEI of WMA was 76.4, which was much less than the corresponding value for HMA. Samples were also tested for Marshal stability, resilient modulus and wheel tracking (WTT) tests according to ASTM D6927, ASTM D4123 and BS EN12697-22 procedures, respectively. The control samples perform better in the stability test. The resilient modulus of WMA was only about 10% lower compared to HMA. Resistance to permanent deformation was measured from the dynamic stability (DS) or the number of wheel passes per 1 mm rut depth over the last 15 minutes in a 60-minute tracking test. The DS of HMA, WMA compacted at 125 °C and 115 °C were 3138, 3044 and 2837, respectively. From the rutting resistance standpoint, the results are not significantly different. Hence, incorporation of the additive does not adversely affect mixture rutting resistance despite the lowered production temperature.

Influence of ageing on high content polymer modified asphalt mixture stripping, cracking and rutting performances

The outstanding properties of High Content Polymer Modified Asphalt (HCPMA) have been widely recognised, but there are only scattered studies have investigated the influence of ageing on HCPMA properties, and even fewer researches have discussed this at the mixture level. This study seeks to evaluate the HCPMA mixture performance with the influence of ageing taken into consideration. Mixture stripping, cracking and rutting resistances were evaluated by the means of Cantabro loss test, Semi-Circular Bend (SCB) test and Hamburg Wheel-Tracking (HWT) test, respectively. Both laboratory short-term ageing and long-term ageing were conducted and different ageing durations/temperatures were investigated. Results indicated that an unaged HCPMA mixture (7.5% SBS) has much improved overall performance over conventional modified mixture (4.5% SBS). However, it is also more ageing susceptible. All three types of performances evaluated in this study were negatively influenced by ageing. Stripping and rutting resistance were more sensitive to higher ageing temperatures while cracking resistance was sensitive to both higher ageing temperatures and longer ageing duration. Mixture rutting performance after ageing is seldom considered as a critical performance. However, in the case of HCPMA mixture, it may need extra attention and related specification should be developed. Moreover, binders extracted from the aged mixtures were examined and the results well agreed with the mixture ageing behavior except for the inconsistency between the 210°C_2 h aged mixture’s deepest rutting depth and its smallest Jnr3.2 value, which pointed out the possibility that Jnr3.2 parameter from MSCR may overestimate the contribution of binder elasticity on mixture rutting resistance.

Modelling of aggregates’ contact mechanics to study roles of binders and aggregates in asphalt mixtures rutting

Rutting resistance is one of the essential needs in the design of asphalt mixtures. Volumteric properties, binder modification, aggregates properties, and performance tests such as the triaxial test and wheel tracking test are used today to qualify the rutting resistance in practice. However, these tools are used on a trial and error basis and are mostly based on experience to achieve better resistance. With all the experience available today, it is still not clear what is the contribution of aggregate structure, what air-voids content should be used, and if plastomeric or elastomeric modifiers are preferred for better resistance. While compiling larger databases and expanding the types of aggregates and binders used in testing could help, a more fundamental understanding of how aggregate contacts are formed and how binders can contribute to actual mechanics of rutting resistance is a better path for designing of mixtures. In the last decade, a significant improvement in imaging and multi-scale modelling has been achieved, which allows looking closer at how binders and aggregates could affect rutting resistance. One of the most challenging aspects of this modelling effort is dealing with aggregates proximity zones or contacts and how the response of mixture changes when aggregates come into contact. This paper includes a proposal for addressing this challenge and provides a solution that is simple yet effective in better simulating of measured rutting in the laboratory. The paper also includes an application of the model to simulate mixtures produced with plastomeric and elastomeric modifiers with different viscoelastic properties. The mixtures include different gradations to represent fine and coarse gradations of aggregates. Results demonstrate that packing of the aggregates is significantly affected by the binder modifiers as some additives can result in a better-packed aggregate internal structure that is much more effective in improving rutting resistance of mixtures. It is expected that the improved modelling of contact zones will aid in more rational selection of aggregates and modification techniques in the mix design phase to enhance the rutting resistance of asphalt pavements.

Influence of Environmental Conditions on the Performance of Bituminous Mixtures

Abstract Aging and moisture damage are considered as major environmental factors which affect the performance of bituminous mixtures. This study investigated the effect of aging and moisture invasion on the performance of bituminous mixtures in terms of tensile strength and rutting resistance. Two different types of aggregates sources and one unmodified bituminous binder with and without warm additive were used. Bituminous mixtures were subjected to two levels of aging conditions (short-term and long-term aged) and two levels of moisture conditions (1 and 3 freeze-thaw cycles). A total of 24 different combinations were investigated for tensile strength and permanent deformation characteristics. Mineralogical investigations characterized the crushed stone as calcareous and bank run as siliceous aggregates. Results from this study demonstrate that levels of aging had a significant impact on the tensile strength of bituminous mixtures with warm mix additive as compared to conventional bituminous mixtures. Fracture work density, a surrogate cracking parameter was able to adequately capture the influence of aggregate mineralogy on the moisture susceptibility of long term aged mixtures. In addition, moisture conditioning was found to influence fracture work density of mixtures more than aging. Further, the rutting resistance of mixtures was determined in terms of flow numbers obtained using Francken model. In general, the rutting resistance of conventional mixtures was relatively higher than a mixture with warm mix additive. As expected, the flow number of conventional mixtures increased with aging and further reduced with moisture conditioning. Interestingly, the flow numbers of bituminous mixtures with warm mix additive was not negatively impacted by moisture at short term aged conditions. However, flow number of both mixtures after long term aging exhibited a similar trend. Additionally, statistical analysis showed that an increase in freeze-thaw cycles from one to three did not significantly impact the tensile characteristics of the mixtures.

INVESTIGATION ON INDICES OF WORKABILITY AND RUTTING RESISTANCE FOR WEARING COURSE MIXTURES

Simple indices easily help to evaluate a performance of hot mix asphalt mixtures. This study aimed to develop a simple workability index and rutting resistance index for wearing course mixtures. Seven aggregate gradations were prepared to investigate dense, coarse, and fine-graded hot mix asphalt mixtures. The study used the Marshall compactor to fabricate specimens. The Superpave Gyratory Compaction was employed to measure the workability of the seven blends, namely the workability energy parameter of asphalt mixtures. The study also conducted Wheel Tracking Test to evaluate rutting resistance of those mixtures. The results showed a strong relationship between the workability index and the workability energy of hot mix asphalt mixtures, namely increasing the workability energy of mixtures with increasing the workability index value. The workability energy value of an asphalt mixture may be high when the area of continuous maximum density for a proportion of stone, which illustrates a degree of far away from the Fuller maximum density line, is low. Moreover, the rutting resistance index correlated well with rutting resistance of the hot mix asphalt mixtures.

Effects of phosphorus slag powder and polyester fiber on performance characteristics of asphalt binders and resultant mixtures

The objective of this study was to investigate the effect of phosphorus slag powder (PSP) and polyester fiber (PF) on the rheological properties of asphalt binder and performance characteristics of resultant mixtures. It is also of great interest to determine whether the PSP can be used to replace conventional filler (i.e., limestone powder) without negatively affecting the mixture performance. A laboratory experiment was developed which included characterization of PSP and PF, determinations of the optimum content of PF and optimum PSP-binder ratio, and performance evaluation of asphalt mixtures with various combinations of PF, PSP and limestone powder. The PSP behaved effectively as a mineral filler such that it increased the binder viscosity resulting in enhanced mixture rutting resistance. The use of PF significantly improved the mixture resistance to low-temperature cracking and moisture damage as indicated by the flexural strain and tensile strength ratio results. Overall, mixture with 3% PF at the PSP-binder ratio of 1.0 outperformed the others with limestone powder and/or PF, indicating the feasibility of recycling PSP and PF into asphalt mixtures for satisfactory mixture performance.

Characterization of rutting resistance of EBS-modified asphalt mixtures

ABSTRACTDriven by Kyoto protocol to reduce the gas emission, warm mix asphalt (WMA) as an alternative of hot mix asphalt has gained huge interest among researchers. Despite many advantages, rutting resistance of WMAs is always questionable. In this study, ethylene bis(stearamide) (EBS) was used as a wax-based additive to produce WMAs. Samples were produced at three different compaction temperatures. To evaluate rutting resistance of mixtures, all cylindrical specimens were tested by dynamic creep and dynamic modulus tests at various compaction temperatures. Results indicate that rutting resistance of EBS-modified samples are remarkable, especially when compaction temperature is low.

Flow number predictive models from volumetric and binder properties

This study was conducted to develop flow number (FN) predictive models for asphalt concrete mixtures (AC) using Superpave volumetric and binder properties. The FN test is the recommended procedure for evaluating rutting resistance of AC mixtures under the AASHTO mechanistic empirical pavement design guide (MEPDG). FN tests were conducted at 54°C on 13 plant-produced laboratory-compacted AC mixtures using repeated creep loads of magnitude 206kPa for 10,000cycles or until an accumulated strain of five percent. The results were compared with key Superpave mixture volumetrics and binder specification parameters. First-order multiple regression models were developed to describe the relationship among FN, mixture volumetrics, and Superpave rutting parameter (G*/sinδ). The results showed that FN was strongly correlated (R2=0.94) to G*/sinδ, effective binder content, air voids, and dust to effective binder ratio. The results demonstrate a clear link between FN and mixture volumetric and binder properties and suggest FN could be considered as potential rutting specification parameter for QC/QA purposes in the field. The results may also be useful for optimizing the laboratory mix design process by directly relating certain Superpave specification parameters to mixture rutting resistance.

Investigation of Simple Performance Characteristics of Plant-Produced Asphalt Mixtures in Tennessee

With the recent adoption of the dynamic modulus, flow number, and flow time tests as simple performance tests (SPTs) to complement the Super-pave® volumetric mixture design and the selection of dynamic modulus as a basic material property input in the new AASHTO 2002 M-E design guide, SPTs have been receiving more attention and have been more often used in the asphalt community. This paper presents the results from a laboratory study with the asphalt mixtures used in Tennessee obtained by SPTs. Eleven plant-produced mixtures with asphalt cements with different PGs and different aggregates were evaluated by the dynamic modulus and flow number tests. The asphalt pavement analyzer (APA) test was also included in this study to characterize the rutting resistance of asphalt mixtures. The results indicated that generally repeatable data can be obtained from the dynamic modulus test. The flow number test was able to identify the effects of both asphalt cement and aggregate in the rutting resistance of mixtures. The SPTs and APA test produced consistent results in this study.

Comparison of rutting resistance of unmodified and SBS-modified Superpave mixtures by accelerated pavement testing

Superpave asphalt mixtures have been used in highway pavements in the US since the late 1990s. Modified binders have also been used in some of the Superpave mixtures in an effort to increase the cracking and rutting resistance of these mixtures. Due to the short history of these mixtures, it is still too early to assess the long-term performance of these Superpave mixtures and the benefits from the use of the modified binders. This paper presents the results of a full-scale pavement-testing program to evaluate the rutting resistance of Superpave mixtures with and without polymer modification using a Heavy Vehicle Simulator. Results from the HVS tests showed that the pavement sections with two 5-cm lifts of SBS-modified mixture clearly outperformed those with two 5-cm lifts of unmodified mixture, which had two to two and a half times the rut rate. The pavement sections with a lift of SBS-modified mixture over a lift of unmodified mixture practically had about the same performance as the sections with two lifts of SBS-modified mixture when tested at ambient temperature, and had only about 20% higher rutting than those with two lifts of modified mixture when tested at 50 °C. The test section with two lifts of SBS-modified mixture and tested at 65 °C still outperformed the test sections with two lifts of unmodified mixture and tested at 50 °C. Rutting of the unmodified mixture was observed to be due to a combination of densification and shoving, while that of the SBS-modified mixture was due primarily to densification.

Use of Superpave Gyratory Compaction Data for Rutting Prediction

This paper presents the estimation results of an improved nonlinear rutting progression model for asphalt concrete mixes. Rutting is modeled as a function of traffic, temperature, and mix characteristics, including voids filled with asphalt, asphalt content, in-place air voids, surface area, and the densification slope. Mixed effects, an advanced statistical technique that allows the consideration of several sources of randomness and autocorrelated disturbances, is used for the estimation of the model parameters. The estimation results with measurements from WesTrack indicate that the model is statistically significant. Further, the model correctly anticipates the dramatic failure of the WesTrack replacement sections (approximately 10–20 mm in a few days). Mixture rutting resistance is linked to the aggregate resistance to densification, as measured by the densification slope in the Superpave gyratory compactor. The model may provide a basis for identification of probable mix performance in the field with...

Performance of Modified Asphalt Binders with Identical High-Temperature Performance Grades but Varied Polymer Chemistries

The rutting resistances of mixtures that contain polymer-modified asphalt binders with identical performance grades but varied polymer chemistries were evaluated. Eleven asphalt binders were obtained for this study: two unmodified asphalt binders, an air-blown asphalt binder, and eight polymer-modified asphalt binders. Five binders used in a prior study also were included. Asphalt binder properties were measured with a dynamic shear rheometer. Mixture rutting resistance was measured by ( a) the shear modulus, G*, and the Superpave® binder rutting factor, G*/sinδ; ( b) cumulative permanent shear strain (CPSS); ( c) the rut depths from the French pavement rutting tester (French PRT); and ( d) the creep slopes from the Hamburg wheel-tracking device. CPSS and rut depths from the French PRT were the primary mixture tests because they were specifically developed to measure rutting resistance under dry conditions. The high-temperature properties of the 11 asphalt binders had a high correlation to mixture rutting resistance as measured by the CPSSs. A weak correlation was found using the French PRT. Both correlations were high when the data from all 16 asphalt binders and mixtures were analyzed. The number of discrepancies between the high-temperature properties of the asphalt binders and mixture rutting resistance was low. A change in high-temperature performance grade from 70 to 76 significantly increased rutting resistance based on both mixture tests.

Zero-Shear Viscosity of Bituminous Binder and Its Relation to Bituminous Mixture's Rutting Resistance

When testing viscosity of polymer-bitumen systems a question arises about interpretation of results as those systems behave as non-Newtonian liquids. A simple equation modeling non-Newtonian behavior of polymer-bitumens was proposed (which is a simplified version of the CROSS model). The equation used enables the calculation of zero-shear viscosity η0 from viscosity measurements conducted under various shear conditions, that is, with rotational viscometer at different shear rates (stresses). Test results are presented of several polymer-modified bituminous binders before and after Thin film oven test aging and discussion of non-Newtonian behavior. The wheel tracking test (Laboratoric Central des Ponts et Chaussées) was conducted for asphalt concrete with several bituminous binders, either plain bitumens or polymer modified. To estimate bituminous mixture's rutting resistance, a new relationship has been proposed to calculate N10 (wheel passes number to rut depth 10 mm). Close correlation was found between N10 and zero-shear (or absolute) viscosity of binders at 60°C, both conventional and polymer modified.

Zero-Shear Viscosity of Bituminous Binder and Its Relation to Bituminous Mixture's Rutting Resistance

When testing viscosity of polymer-bitumen systems a question arises about interpretation of results as those systems behave as non-Newtonian liquids. A simple equation modeling non-Newtonian behavior of polymer-bitumens was proposed (which is a simplified version of the CROSS model). The equation used enables the calculation of zero-shear viscosity η0 from viscosity measurements conducted under various shear conditions, that is, with rotational viscometer at different shear rates (stresses). Test results are presented of several polymer-modified bituminous binders before and after Thin film oven test aging and discussion of non-Newtonian behavior. The wheel tracking test (Laboratoric Central des Ponts et Chaussees) was conducted for asphalt concrete with several bituminous binders, either plain bitumens or polymer modified. To estimate bituminous mixture's rutting resistance, a new relationship has been proposed to calculate N10 (wheel passes number to rut depth 10 mm). Close correlation was found between...

Relationship between absolute viscosity of polymer-modified bitumens and rutting resistance of pavement

New polymer-modified bituminous binders require verification of the relationship between binder properties and road pavement performance, formerly found for conventional road bitumens. The paper deals with one particular problem of polymer-bitumen (PB) viscosity and bituminous mixture rutting resistance. Non-Newtonian, shear-dependent behaviour of PB in a viscosity meassurement has been characterized by a new equation proposed by the author. This equation enables calculation of the absolute (zero shear rate) viscosity of PB and is applied for evaluation of test results at 60and 90°C. The absolute viscosity of PB at 60°C has been correlated with the bituminous mixture's rutting resistance at 45°C. Correlation with other rheological properties of PB is also examined by means of multiple regression analysis.