Laboratory research on evaluating the rutting resistance of natural asphalt concrete mixture

The modification mechanism of modified asphalt with natural asphalt was analyzed through Fourier transform infrared spectrum. The results show that the modification mechanism of both the natural asphalt and petroleum asphalt is mainly a physical blending process. The polar functional groups contained in natural asphalt make modified asphalt with natural asphalt have characteristic good scaling resistance and water stability. Subsequently, the carbon emissions of each link of asphalt production stage were quantified, and the influence of mining, transportation, and processing on the total carbon emissions were all analyzed by establishing the carbon emission calculation model of asphalt production. The calculation results of GREET model showed that the equivalent carbon dioxide emission (CO2e) of rock asphalt mining was only 9.4% of that of crude oil production. At the same time, the CO2e of modified asphalt with natural asphalt processing was 44.7% lower than that of petroleum asphalt, and the carbon emission of rock asphalt transportation accounted for only 1/3 of that of petroleum asphalt transportation. Furthermore, the increased energy consumption caused by petroleum asphalt transportation and modified asphalt with natural asphalt processing will partially offset the contribution of natural asphalt to reducing carbon emissions. Meanwhile, the CO2e of modified asphalt with natural asphalt was lower than that of petroleum asphalt when the content of natural asphalt exceeded 18%. Thereafter, the analytic hierarchy process calculation results showed that petroleum asphalt processing and transportation had the largest weight of carbon emissions in the production stage of modified asphalt with natural asphalt. Ultimately, it is significant to further reduce carbon emissions by increasing the content of natural asphalt, which will then inevitably lead to the reduction in the production and transportation energy consumption of petroleum asphalt.

For over a century, the global consumption of asphalt binder in asphalt mixture production has been substantial. In the Heet region (west of Iraq), two distinct forms of natural asphalt (NA) deposits exist: rock asphalt and sulfur spring asphalt. This study focused on using NA sourced from sulfur springs. The aim was to investigate the potential of incorporating NA into local asphalt mixtures. To achieve this, NA was heated to 163°C for varying durations. After heat treatment, laboratory tests were conducted on NA. The findings suggest that by heating NA for 20 hours, it conforms to Iraqi specifications in terms of physical properties. Furthermore, compared to conventional petroleum asphalt, treated NA showed greater resistance to temperature fluctuations, making it ideal for hotter climates. The study also found that NA enhances mechanical properties significantly. Specifically, the NA mixture recorded the highest indirect tensile strength, with a tensile strength ratio of 81.2%, a slight increase of 0.37% over traditional mixes. In summary, NA mixtures exhibit commendable performance. Given its abundance and affordability in Iraq, after considering heat treatment costs and environmental impact, NA holds promise for the future of asphalt concrete production for the construction of flexible pavement.

Because of the differences in material composition and structure, different natural asphalt will lead to different road performances and technical approaches. Based on years of research data, the composition and characteristics of different natural asphalt are reviewed. It is considered that the difference of performance of different natural asphalt is closely related to asphalt content and ash content. Aging property is related to oil content and microstructure of asphaltene. Because the mineral composition of lake asphalt is mostly volcanic ash, it shows different modification effect from natural rock asphalt, and has more advantages in the comprehensive performance of asphalt mixture, especially in low temperature performance and fatigue resistance.

This research utilized natural asphalt (NA) deposits from sulfur springs in western Iraq. Laboratory tests were conducted to evaluate the performance of an asphalt mixture incorporating NA and verify its suitability for local pavement applications. To achieve this, a combination of two types of NA, namely soft SNA and hard HNA, was blended to create a binder known as Type HSNA. The resulting HSNA exhibited a penetration grade that adhered to Iraqi specifications. Various percentages of NA (20%, 40%, 60%, and 80%) were added to petroleum asphalt. The findings revealed enhanced physical properties of HSNA, which also satisfied the requirements outlined in the Iraqi specifications for asphalt cement. Consequently, HSNA can serve as an asphalt binder to produce asphalt mixtures for flexible paving construction. Notably, HSNA mixtures exhibited greater Marshall stability and stiffness index when compared to traditional mixtures. The results from indirect tensile strength (ITS) and tensile strength ratio (TSR) tests indicated that the 80NA mixture displayed the highest ITS values and a TSR of 81.36%, surpassing the TSR of the mixture incorporating petroleum asphalt by 0.57%.

Extensive diametral repeated load tests were performed on asphalt concrete specimens. Extensive repeated load triaxial tests were performed on base and subgrade materials. New resilient modulus test methods were developed for these materials and presented in the form of American Association of State Highway and Transportation Official (AASHTO) type test procedures. The repeated load test is not easy to perform and must be carried out on a carefully calibrated testing system including using synthetic specimens. To minimize human errors, a fully automated, closed loop testing and data acquisition system should be used. For asphalt concrete, the Strategic Highway Research Program (SHRP) Load Guide diametral testing device should be employed to minimize rocking. A mountable extensometer provides less variance and hence better repeatability for resilient modulus measurement. Poisson's ratio can be evaluated using a surface mounted linear variable differential transformer (LVDT) to measure vertical deformation and externally mounted LVDTs to determine horizontal deformation. The value of Poisson's ratio used to determine the resilient modulus has an important influence on its value. Poisson's ratio should be measured rather than assumed. To reliably determine resilient modulus, axial deformation of base and subgrade materials should be measured on the specimen using either (1) an optical extensometer, (2) non-contact proximity gages or (3) small LVDTs supported by lightweight clamps. The optical extensometer is highly recommended. For granular materials a vacuum triaxial test offers an excellent approach when an optical extensometer is used. An unconfined repeated load test is recommended for cohesive subgrade soils. For cohesive soils, bedding irregularities at specimen ends, specimen aging and soil structure must all be properly considered to obtain reliable resilient moduli.

Over the last decade, unexpected and sudden pavement failures have occurred in several provinces in South Korea. Some of these failures remain unexplained, further illustrating the gaps in our knowledge about binder chemistry. To prevent premature pavement distress and enhance road performance, it is imperative to provide an adequate characterization of asphalt. For this purpose, the current research aims at inspecting the chemistry, microstructure, thermal, and physico-rheological properties of two types of asphalt, namely petroleum asphalt (PA) and natural asphalt (NA). The binders were extensively investigated by using elemental analysis, thin-layer chromatography with flame ionization detection (TLC-FID), matrix-assisted laser desorption ionization time-of-fight mass spectroscopy (MALDI-TOF-MS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), Nuclear magnetic resonance spectroscopy (1H-NMR), ultraviolet and visible spectroscopy (UV-VIS), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), penetration, softening point, ductility, and viscosity tests. The findings of this research have revealed the distinct variations between the chemical compositions, microstructures, and thermo-rheological properties of the two asphalts and provided valuable knowledge into the characteristics of the binders. Such insight has been effective in predicting the performance or distress of road pavement. This paper will, therefore, be of immediate interest to materials engineers in state highway agencies and asphalt industries.

The depletion of petroleum reserves and increasing environmental concerns have driven the development of eco-friendly asphalt binders. This research investigates the performance of natural asphalt (NA) modified with waste engine oil (WEO) as a sustainable alternative to conventional petroleum asphalt (PA). The study examines NA modified with 10%, 20%, and 30% WEO by the weight of asphalt to identify an optimal blend ratio that enhances the binder’s flexibility and workability while maintaining high-temperature stability. Comprehensive testing was conducted, including penetration, softening point, viscosity, ductility, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results reveal that WEO effectively softens NA, improves ductility, and enhances workability, with the 20% WEO blend achieving the best balance of physical and rheological properties. Chemical analysis indicates that WEO increases carbon content and reduces sulfur and impurities, aligning NA’s composition closer to PA. However, excessive WEO (30%) compromises thermal stability and deformation resistance. The findings underscore the potential of WEO-modified NA for sustainable pavement applications, with 20% WEO identified as the optimal content to achieve performance comparable to conventional petroleum asphalt while promoting environmental sustainability.

Recycled Asphalt Pavement (RAP) using old aggregate asphalt mixture is manufactured by adding asphalt content and aggregates that have been lost due to fatigue or the aging process. In addition to reducing the amount of waste, the recycling process saves road maintenance costs. In the present study, recycled rubber powder, Crumb Rubber (CR), from vehicle tires is employed to improve the performance of RAP. The type of asphalt used in the study is natural asphalt from Buton Island, which is subjected to an asphalt refining process termed Refine Buton Asphalt. CR with different contents of 0.5%, 1%, 1.5%, 2%, and 4% were added to the aggregate, and subsequently mixed with asphalt through a hot mixture process. These variations in CR content corresponded to 0% and 1% additions to the RAP mixture, while the addition of waste-engine oil was determined by a penetration test. The resilient modulus of hot asphalt mixture was tested using Universal Material Testing Apparatus (UMATTA) at various temperatures. The results of the study indicate that the addition of CR increases the stability and resilient modulus of RAP.Recycled Asphalt Pavement (RAP) using old aggregate asphalt mixture is manufactured by adding asphalt content and aggregates that have been lost due to fatigue or the aging process. In addition to reducing the amount of waste, the recycling process saves road maintenance costs. In the present study, recycled rubber powder, Crumb Rubber (CR), from vehicle tires is employed to improve the performance of RAP. The type of asphalt used in the study is natural asphalt from Buton Island, which is subjected to an asphalt refining process termed Refine Buton Asphalt. CR with different contents of 0.5%, 1%, 1.5%, 2%, and 4% were added to the aggregate, and subsequently mixed with asphalt through a hot mixture process. These variations in CR content corresponded to 0% and 1% additions to the RAP mixture, while the addition of waste-engine oil was determined by a penetration test. The resilient modulus of hot asphalt mixture was tested using Universal Material Testing Apparatus (UMATTA) at various temperatures. The r...

Natural asphalts (NAs) can be an economical and environmental alternative in pavement construction. Most studies have investigated them as binder and asphalt mixture modifiers due to their high compatibility with conventional asphalts. In this article, some of the studies carried out on the use of NA in pavements are summarized and described in a chronological order. The main aspects described in the reviewed studies were the type of asphalt binder or modified mixture, the type and content of the modifier, the manufacturing processes of the asphalt or modified mixture, tests performed, and main results or conclusions. In general terms, NAs show better performance as binder and asphalt mixture modifiers in high-temperature climates. Additionally, they tend to improve water and ageing resistance. As main limitations, it is reported that NAs tend to negatively affect the workability and performance of asphalt mixtures in low-temperature climates. Finally, recommendations for future study topics are provided at the end of this paper.

The study included six bitumens, one unmodified and five modified, and their corresponding asphalt mixtures. The first bitumen was the base bitumen and further five variants were made by the authors using the same base bitumen and different combinations of modifiers which included styrene-butadiene-styrene (SBS), Fischer–Tropsch wax (FTW), ethylene vinyl acetate (EVA), reactive elastomeric terpolymer (RET), and natural asphalt (NA). The influence on the fatigue life of bitumen and asphalt due to modification, bitumen rheology, preload, water storage, and aging was studied. A new temperature range was developed—the fatigue-relevant temperature range (FRTR) for specifying fatigue test temperatures for bitumen and asphalt. A new methodology that includes preload and water storage was also done to study the active adhesion behavior between bitumen and aggregates and its influence on fatigue life. Overall, modifications showed positive influence on the fatigue behavior of bitumen and asphalt. Variants E (SBS and RET) and F (SBS and NA) showed the greatest positive influence with an increase in the fatigue life by 500% and 210% for bitumen and 200% and 375% for asphalt respectively. With water storage, the fatigue life reduced by 500% for unmodified asphalt and in the range of 333–1350% for modified ones. Due to aging, the fatigue life reduced from 700% for unmodified and between 700% and 2500% for modified asphalt mixtures.

Amorphous carbon powder (ACP), an industrial waste material, is a potential asphalt binder modifier. In this study, the effect of ACP on the rutting performance of asphalt binders and mixtures was investigated. For this purpose, the frequency sweep, and multiple stress creep recovery tests of asphalt binders and resilient modulus, dynamic creep, and wheel tracking tests of asphalt mixtures were conducted on asphalt binders and mixtures containing 3, 5, and 10% of ACP by weight of total asphalt binder. The results showed that using 10% ACP caused a substantial improvement in the rutting parameter of asphalt binders, and the non-recoverable creep compliance values at both 0.1 and 3.2 kPa stress levels decrease by about 80% when modified with 10% ACP. The asphalt mixture results indicated that the indirect tensile strength, wheel tracking, and resilient modulus at 25°C enhanced by about 25%, 43%, and 40%, respectively when 10% ACP modified asphalt binder was used. Therefore, in addition to being a positive action in environmental protection, modifying asphalt binders with 10% ACP can improve the high-temperature performance of asphalt binders and mixtures.

The Superpave indirect tension (IDT) system was modified to determine the short-loading-time stiffness of asphalt mixtures from resilient modulus, creep, and strength tests. The idea was not only to provide a more accurate method to determine the resilient modulus, but also to determine whether reasonable measures of short-loading-time stiffness could be obtained from tests that provide other properties and thereby minimize the amount of testing needed to characterize asphalt mixtures. It was found that even when evaluated at very short loading times, the stiffnesses determined from the different tests were significantly different. Detailed evaluation indicated that the differences can be explained by the differences in loading rates between the tests. In general, stiffnesses from the different tests all appeared to be reasonable and followed the same trend. However, since the rheological behavior of asphalts and mixtures varies, stiffnesses from different tests were not directly related. Therefore, although the interpretation methods developed in this study for creep and strength tests appear to provide a reasonable alternative to the resilient or dynamic modulus, the short-loading-time stiffnesses determined from these tests are not directly comparable with the resilient or dynamic modulus or with each other. The work illustrates the sensitivity of stiffness to relatively small changes in loading rate and other variables, which emphasizes the need to precisely define load pattern, load level, and data interpretation methods to determine asphalt mixture stiffness at short loading times.

The nanopowdered VP108 was selected and applied into the base asphalt binder and mixture. The Marshall binder and mixture tests were conducted to evaluate the mechanical and pavement performance of base and VP108 modified asphalt binders and mixtures. The test results present that the penetration, softening point, penetration index and ductility of VP108 modified asphalt binder improved compared to the base asphalt binder. The mixture test results display that the compression strength, water susceptibility, resilient modulus and cleavage strength of VP108 modified asphalt mixture enhance compared to the base asphalt mixture. Therefore, the overall performance of VP108 modified asphalt binder and mixture improves compared to the base asphalt binder and mixture, such as the high temperature performance, resilient modulus and water resistance property.

Nanoclay application to asphalt concrete: Characterization of polymer and linear nanocomposite-modified asphalt binder and mixture

Analysis of use of natural fibers and asphalt rubber binder in discontinuous asphalt mixtures