Deformation Of Hot Mix Asphalt Research Articles

Effect of Fine Aggregates and Mineral Fillers on the Permanent Deformation of Hot Mix Asphalt

Conventional asphalt pavement is the dominant mode of passenger and freight traffic in Pakistan. As a result, asphalt pavements suffer from various failures, where rutting, corrugation, and fatigue cracking are significant. Fine aggregates and mineral fillers play a pivotal role in providing structural integrity in asphalt pavements when subjected to traffic and the environment. The current study aims to examine the effects of various locally accessible fine aggregate and mineral filler materials on the interlocking properties of asphalt mixtures in relation to internal friction angle, rutting resistance, and controlling environmental pollution as an indirect benefit, thereby reducing wastes. Four distinct asphalt samples were prepared using cinders, stone dust, natural sand, and surkhi as fine aggregates and mineral fillers, as a full replacement, as per ASTM D1559, confirming the Asphalt Institute’s gradation for asphalt wearing course. Optimum binder contents (OBC) of 4.40%, 4.1%, 6.57%, and 6.63% by weight of Marshall specimen were concluded for asphalt samples containing stone dust, natural sand, cinder, and surkhi, respectively. The results revealed that surkhi, natural sand, stone dust, and cinder all showed a diminishing tendency in developing interlocking properties in asphalt mixtures at internal friction angles of 35°, 33.7°, 32°, and 28.4°, respectively. The wheel tracking test results revealed that the asphalt samples made with surkhi as fine aggregates and fillers have the highest rut resistance, whereas samples made with cinders as fine aggregates and fillers have the lowest rut resistance. The direct shear test showed that fine aggregates with a larger angle of internal friction are significantly more stable in terms of rut resistance than fine aggregates with a smaller angle of internal friction. The current research will help to prevent pavement rutting and corrugation by adding surkhi into asphalt pavements, with the reduction in brick kiln waste providing an indirect benefit.

Empirical correlation of the modified wheel tracker (MWT) and the dynamic creep test for evaluating the permanent deformation of hot mix asphalt (HMA)

The wheel tracking test (WTT) has been extensively used for laboratory characterization of permanent deformation of hot mix asphalt (HMA). However, the fully-confined setup of the device is unable to capture the tertiary zone where shear deformation takes place. This makes the permanent deformation resistance characteristics of HMA difficult to analyze. Hence, a modified wheel tracker (MWT), with unconfined lateral sides along the wheel tracking direction was utilized in this study, which can capture the tertiary flow (referred to as the flow number (FN)). The dynamic creep test, which yields FN, is a common laboratory test which has the ability to characterize permanent deformation considering the shear behavior. The study investigated the relationship of the MWT and the dynamic creep test utilizing the permanent deformation and permanent microstrain data from the respective tests. A novel parameter, FN-Index was explored. The permanent deformation parameters derived from the MWT were well correlated with the dynamic creep test. The MWT showed promising repeatability for the FNs.

Determination of the permanent deformation of hot mix asphalt with natural desert sand

This study attempts to evaluate the permanent effects of using natural desert sand (NDS) on the behaviour of asphalt mixtures. Previous studies have focused on the characterization of permanent properties of asphalts that use NDS. This study aims to determine the effect of using fine aggregate materials NDS and manufactured crushed sand (MCS) in hot mix asphalt (HMA) and how this affects the permanent deformation of the final HMA. The NDS samples were collected from the desert regions. The Index of Aggregate Particle Shape and Texture (IAPST), Marshall, the Rutting analyzer and the Complex Modulus tests were undertaken to analyze and compare the properties of HMA containing two different types of bitumen binders, PG70-10 and B60/70. The performance of mixtures containing PG70-10 was found to be superior in comparison with mixtures containing B60/70. These results are critical for engineers planning roadworks in hot and arid environments and allow for significant cost reductions by using locally available materials (i.e. NDS) instead of more costly MCS. With these findings, it is possible to partly use NDS in HMA for low volume roads (LVRs).

Effects of different fillers on pavement deformation of hot mix asphalt in hot climates

Permanent deformation in the form of rutting is one of the major distresses affecting flexible asphalt pavements. This is a serious issue in hot countries and is closely associated with the viscosity of the bitumen binders used. In hot countries, temperatures can exceed 45 °C. Even in the construction of primary roads, bitumen 60/70 (B60/70), which is a relatively low-grade and soft bitumen, continues to be used for Hot Mix Asphalt (HMA) construction. Libyan asphalt concrete pavement roads therefore develop extreme deformations in the form of rutting. This study tests the effects of filler materials on mechanical and volumetric HMA performance with recourse to cellulose fiber (CF) and Ordinary Portland Cement (OPC). CF and OPC were added to a B60/70 HMA mix according to Superpave design specifications. Three percentages of OPC (2%, 4%, and 6%) and three different percentages of CF (0.25%, 0.5%, and 0.75%) were used as filler; there was also a control mix with no filler (0%). Mix performance was assessed with the rutting analyzer and The Indirect Tensile Stiffness Modulus (ITSM). ITSM test were conducted at −5 °C, 10 °C, 25 °C and the rutting analyzer test was conducted at 60 °C to simulate temperatures in the region. The mixes using cellulose fiber performed better than those with OPC. The results suggest potential budgetary savings because roadworks projects can use inexpensive additives instead of more expensive bitumen binders.

Permanent Deformation of Hot Mix Asphalt (HMA) using Dynamic Modulus Simple Performance Test

Premature pavement breakdown can be caused by permanent deformation that can contribute to lower riding comfort for road users and an increase in maintenance costs. Dynamic modulus Simple Performance Test (SPT) test are considered to be significant in describing the permanent deformation of hot mix asphalt. In this study, Marshall method of mix design were used in order to prepare four asphalt mixtures comprising different content of Nanopolyacrylate (NP) polymer (0%NP, 2%NP, 4%NP and 6%NP). This study was aimed to evaluate the influence of the NP modified mixture on the permanent deformation. The Performance Grade PG64-22 was obtained by mixing the conventional bitumen (PG64-22) with nanopolyacrylate. Dynamic Shear Rheometer (DSR) at different aging condition were conducted in order to characterise the bitumen performance. While, the Simple Performance Test (SPT) was used to characterize rutting and fatigue on Marshall HMA mixes. Results from the study presented that, NP modified bitumen has a significant impact on the dynamic and rutting resistance. The addition of nanopolyacrylate significantly enhances the rheological properties of asphalt bitumen. The results revealed that 4%NP has high potential to improve rutting and fatigue resistance.

Effects of different bitumen modifiers on the rutting and cracking resistance of hot mix asphalts

ABSTRACTIn this study, four different additives (Styrene–butadiene–styrene (SBS), Trinidad Lake Asphalt (TLA), Iranian Gilsonite (IG) and American Gilsonite (AG)) were used in bitumen modification. The rheological properties of bitumen were improved with the additive usage, and the desired performance grade (PG 70-34) was achieved by using additives in pure bitumen (PG 58-34) at the indicated ratios. Wheel tracking tests and semi-circular bending tests were applied for hot mix asphalt (HMA) samples. The main results showed that all the additives increased resistance to permanent deformation of HMAs, and that TLA was the most effective additive. In addition, it was found from the semi-circular bending tests that deformation values of mixtures prepared with modified bitumens and subjected to long-term ageing decreased. As a result, long-term aged and modified bitumen mixtures exhibited more brittle behaviour. The increase in maximum load values led to an increase in the area under the load-strain curves. Thus, crack propagation resistance of mixtures prepared with modified binders was increased.

Laboratory evaluation of seashells used as fine aggregate in hot mix asphalt

ABSTRACTOyster farming annually generates millions of empty hard seashells as by-product waste in municipal landfills worldwide. Using this waste as fine and coarse aggregates as construction materials offers a low energy consumption alternative to recycling and mining of virgin materials. This research explores the use of seashell as a cost-effective replacement of virgin fine aggregate in hot mix asphalt (HMA). The properties of HMA mixtures with seashells were investigated using indirect tensile strength, permanent deformation and moisture susceptibility tests; tests used in standard practice in Perú. The results indicate that seashells can be used as fine aggregate improving the indirect tensile strength and the permanent deformation of HMA. Seashells in the asphalt mixture reduced moisture susceptibility compared to conventional HMA, with an increase of tensile strength ratio (TSR) values of 22–262%, a very important finding since with areas of Perú recently experiencing severe flooding events where seashells have the potential to reduce stripping. The laboratory study also showed that seashell sizes of 300–2.36 mm yielded highest TSR values. Replacement of fine aggregate with seashells increases total HMA cost by about 2.9–4.6%.

Effect of aggregate gradation on permanent deformation behavior of a warm mix asphalt

Abstract In this study, the rut susceptibility of warm mix asphalt (WMA) was evaluated by laboratory material characterization tests that included repeated creep testing using universal testing machine (UTM-5P) on WMA and conventional hot mix asphalt (HMA) mixtures. With regard to the fact that aggregate makes up a high proportion of volume and mass of mixtures, this parameter is considered as an important constituent of asphalt concrete. So, one aggregate source, three gradations and three different percentages of Sasobit® content were used to manufacture mixtures. Four creep parameters, namely, flow number (FN), creep stiffness (CS), creep strain slope (CSS) and secondary initial point (SIP), were used to analyze the test results. The primary objective of this research effort was to conduct a comparison between permanent deformation of HMA and WMA mixtures and also to evaluate the effect of aggregate gradation and different Sasobit® contents on introduced creep parameters. Analysis of data shows that the creep behavior of both asphalt mixtures (HMA and WMA) was influenced by aggregate gradation and also by Sasobit® content. Comparison of test results between HMA and WMA exhibits that, in general, WMA mixtures exhibit improved rut resistance compared to conventional mixtures. Also, it is concluded that creep strength of WMA mixes are more susceptible to change in aggregate gradation compared to HMA mixes, while increasing in Sasobit® content produce more stable mixtures. In addition, it is determined that finer aggregate gradations were more influenced by change in the Sasobit® content.

열분해 카본블랙 사용량에 따른 밀입도 아스팔트 혼합물 성능 평가

본 폐타이어로부터 추출한 열분해 카본블랙(PCB)을 13mm 표층용 밀입도 아스팔트 혼합물 공용성능을 평가하였다. 최적배합설계를 시행하였고, 최적아스팔트 함량은 5.8%을 이용하였다. 아스팔트 혼합물의 탄성계수 평가를 위해 자유단 공진주 시험하였다. PCB 사용량이 증가하면, 측정된 탄성계수는 감소하였다. 다만, 감쇄비 변화는 미미한 것으로 나타났다.평가시험은 간접인장강도시험, 소성변형시험 및 포장설계법을 이용한 전산해석을 이용하였다. PCB 사용시 수침 전과 후의 강도감소율이 평균 10% 이하로 나타났다. 소성변형의 경우 PCB 10% 이상 사용시 오히려 소성변형이 크게 발생하였다. 포장 설계법 전산해석으로부터, PCB 5% 사용시 Top-Down 및 Bottom-Up 균열 저항성이 증가하였고, 소성변형 저감 효과가 크게 나타났다. 열분해 카본블랙 10% 및 15% 사용시 소성변형은 적게 나타났지만, 내구성은 크게 저하되는 것으로 나타났다. 전체적으로 PCB 5%를 이용한 표층용 아스팔트 혼합물의 공용성이 가장 우수한 것으로 나타났다. Using the pyrolyzed carbon black (PCB) from waste tires, the performance of 13 mm dense-graded hot mix asphalt was evaluated. The Marshall mix design was carried out and the measured optimal asphalt content was 5.8%. The impact resonant test was conducted to obtain the elastic modulus and damping ratio of the hot mix asphalt. The elastic modulus of HMA increased with increasing amount of PCB. On the other hand, there was no significant change in the damping ratio. The Marshall mix design, indirect tensile test, permanent deformation test, and program analysis were carried out. The strength ratio of the PCB modified asphalt mixtures was within 10%. More 10% of PCB was not good for the permanent deformation of hot mix asphalt. From the pavement design program, the use of 5% PCB in hot mix asphalt showed a decrease in the top-down crack, bottom-up crack, and permanent deformation. Judging from the limited test and analysis, the use of 5% PCB is good for enhancing the pavement performance.

EFFECT OF AGGREGATE GRADATION AND TYPE ON HOT ASPHALT CONCRETE MIX PROPERTIES

Mineral aggregates make up 90 to 96% of a HMA mix by weight or approximately 75 to 85% byvolume. The properties of the mineral aggregates have significant affects in performance of ourroadways which offers the possibility of investment in these properties towards resisting differentranges of external applied loads and environmental conditions. Therefore, aggregate characteristicsdeeply affect the performance of asphalt pavements. Gradation is one of the importantcharacteristics of aggregates affecting permanent deformation of hot mix asphalt. The objective ofthis research is to investigate the impact of aggregate gradation variations on various properties ofasphalt concrete mixtures. Fine, medium and coarse gradation mixtures for different aggregate typeswere tested to investigate the effects of variation in the aggregate types and gradation on mixproperties. The asphalt contents of the mixes were maintained at the job mix design contents.Properties investigated were, Marshall Stability, Marshall Flow, unit weight, air voids, and voids inmineral aggregate. Analysis of the considering different aggregate type data revealed that the finecoarseand coarse-fine gradation variations had the greatest impact on mix.The research program concentrated on the Marshall Design criteria for bituminous mixes. Theresults indicated that optimum asphalt content (OAC) is different due to aggregate type A coarsegrading with 25 mm maximum size is found to give the most satisfactory result from the stand pointof stability, stiffness, and voids characteristics. Test results reveal that the bituminous concrete withWCA can give satisfactory results when they are constructed using coarse gradation.

Effect of Aggregate Gradation on Rutting of Asphalt Pavements

Permanent deformation (i.e. rutting) of asphalt pavements is one of major types of distress modes experienced in the service life of pavements. Aggregates are one of the key building materials used in the construction industry and the largest portion of an asphalt pavement. Therefore, aggregate characteristics impressively affect the performance of asphalt pavements. Gradation is one of the important characteristics of aggregates affecting permanent deformation of hot mix asphalt. The objective of this research is to investigate the impact of aggregate gradation variations on rutting characteristics of asphalt concrete mixtures.

Time-Temperature and Time-Aggregate Gradation Superposition in Asphalt Mixes

ABSTRACT This study was devoted to evaluate the effect of aggregate gradation, temperature, and type of asphalt cement on the permanent deformation of Hot-Mix Asphalt (HMA). An experimental program was conducted to characterize the viscoelastic deformation response of asphalt mixture using the static creep test. The specimen was exposed to a constant vertical stress of 100 KPa and the vertical deformation of the specimen was monitored through linear variable differential transducers (LVDTs). All tests were conducted within a temperature-controlled chamber to keep the temperature constant throughout the test. Time-temperature and time-aggregate gradation shift factors for each evaluated type of HMA were estimated using plots of log time versus log creep compliance. If the deformations under reference temperature or reference gradation are known, those under given temperature or any given gradation can be obtained using shift factor. Also, viscoelastic models were developed to represent the deformation behavior of HMA under constant stress. The collected data was analyzed to study the effects of aggregate gradation, testing temperature, and asphalt consistency on creep behavior. The effect of temperature variation on creep behavior was found to be more significant at low temperatures and long loading time than those at high temperatures and short loading time. Moreover, aggregate gradation found to has a significant effect on creep behavior, the lowest creep deformation was for HMA prepared using ASTM upper limit gradation. While HMA prepared using ASTM mid-limits aggregate gradation was the least affected by temperature variation.

Use of Georgia Loaded Wheel Tester to Evaluate Rutting of Asphalt Samples Prepared by Superpave Gyratory Compactor

The Georgia loaded wheel tester (LWT) developed by the Georgia Department of Transportation has been used since 1985 in the laboratory during the design stage to evaluate rutting susceptibility of asphalt concrete mixtures. In the LWT testing, asphaltic concrete is subjected to an elevated temperature in a loaded wheel system under repetitive loading conditions, and the permanent deformation induced under the wheelpath is measured. This approach to assess rutting susceptibility was thought to be much more representative than the current test methods and can provide a fast and more accurate means of assessing rutting susceptibility of asphalt concrete under actual field conditions. The asphaltic beam samples used for the LWT testing are prepared by a rolling compaction machine. The new LWT developed in 1992 is described. To promote the concept of using Georgia LWT as a supplement to the Superpave Level 1 design procedure for evaluating permanent deformation of hot-mix asphalt (HMA), a test method utilizing...