Recycled Polyethylene Modified Asphalt Binders and Mixtures: Performance Characteristics and Environmental Impact

This study addresses the effects of recycled polyethylene (RPE) on the performances of both asphalt binders and asphalt mixtures. Whether using RPE in an asphalt mixture might leach harmful chemicals into rainwater or melted snow was also determined. Two processes, wet and dry, were used to formulate the RPE modified asphalt binders and mixtures. In the wet process, RPE was added to asphalt binder. In the dry process, it was added to heated aggregates. RPE from two sources and PG 64-22 virgin asphalt binders from two sources were used in this study. In conclusion, RPE improved the rutting resistance of the asphalt binders and asphalt mixtures. However, it had adverse effects on their resistance to intermediate-temperature and non-load associated cracking. The dry process could produce a mixture with a higher RPE dosage compared with the wet process using one virgin asphalt binder but not the other; thus, the virgin asphalt binder source was a significant factor for the dry process. Based on an embryotoxicity test, it was found that RPE can be used by the asphalt paving industry without creating any significant environmental risks.

Data Mining Statewide Department of Transportation Volumetrically Designed Asphalt Mixture Records

In recent years, the asphalt paving industry has been strained by numerous factors including increased asphalt binder costs, funding that has not kept up with material costs, increased societal pressure to recycle, and deteriorating pavement networks. Mix design should account for the market in which it is used, which is very different now than when today’s volumetric mix design practices were developed (many of the aforementioned factors were less present). Given this reality, a statewide database of all 1,452 approved mix designs in Mississippi from 2005 to 2018 was compiled and analyzed, and the objective of this paper is to present findings, trends, and unintended consequences of exclusive reliance on volumetrics. With volumetrics-only mix design, asphalt content is primarily controlled by voids in mineral aggregate (VMA), which is influenced by aggregate bulk specific gravity (Gsb). Minor Gsb deviations (i.e., within AASHTO d2 s limits), can significantly affect VMA, so much so that 99% of Mississippi’s mixes could be failing VMA while reported VMA passes. This allows mix manipulation and economization, with 0.8% asphalt content reductions possible while still meeting volumetric requirements. Recycled materials can exacerbate this issue, and common approaches to increase asphalt content (decreasing design gyration level or using finer gradations) are ineffective with fixed VMA requirements. Overall, the mix design database analysis agrees with numerous smaller studies but does so with an entire state’s actual practice. This presents a compelling case that volumetrics-only mix design has limitations, and supports ongoing efforts to reintegrate mechanical tests.

Motivational Bonus-System Based On Pavement Installation Temperatures Measurement By Thermographic System (TGS Pavement) In Estonia

Paving is one of the most crucial stage in the matter of road lifespan, since it is the surface layer that has stand up to all the external factors (weather, traffic etc.). Insufficient pavement density caused by thermal segregation during paving works can reduce the lifespan significantly, especially in Estonian climate (freeze-thaw cycles). Modern technology offers different solutions to reduce the risk of low quality in asphalt production and road paving works. Mobile asphalt plant, feeder and thermo-isolated trailers are some piece of equipment, that contractor can use to level up the minimal required quality requirements. The question is, when to use those and which to use? Moreover, is there any possibility to motivate the contractors to put in some extra effort? In Estonia, motivational bonus-system has been established to encourage innovation and reward the extra effort that has been made for quality improvements. The methodology is based on years of experience gained in different researches and pilot-projects. There are no strict rules for the road paving equipment in the methodology – for example contractor can choose himself either the feeder or/and thermo-insulated trailers are used on not. The main requirement is that the temperatures of entire paving process (surface layer) has been measured and analyzed by special thermographic system. Current presentation discusses the symbiosis of bonus-malus system and development of special thermographic system (TGS Pavement) as a multifunctional tool in asphalt paving in Estonia.

The Copolymers and their Effect on the Rheological Properties of Sulfureted Asphalt

Due to the harsh climatic conditions and the maximum loads on the original unmodified asphalt used in paving process, some defects appear over time such as cracks and deformation of roads. This calls for work to improve the rheological properties of asphalt to produce asphalt paving more resistant to the factors above. This study focuses on the use of polymeric mixtures of consumed copolymers in asphalt modification processes. These polymers were thermally treated to find out the temperature at which they could be used in the modification process. Asphalt was treated with different percentages of sulfur as a catalyst under specific conditions of temperature and reaction time, during which the optimum catalyst ratio that can be used in the modification processes was determined. Asphalt was treated with a polymer mixture consisting of (ASA and SBS) (1:1) in different weight ratios with the presence of the optimum catalyst ratio and under the above reaction conditions. Several samples were obtained and the rheological properties of the original and modified asphalt were measured by penetration, softening point, ductility and penetration index calculation as well as calculating the weight percentage of asphaltene. The best sample obtained from the above modification process was determined, and reactions were performed on it again to determine the optimal temperature and reaction time, as well as to determine the optimal percentage of sulfur as a catalyst by measuring the rheological properties of the best sample. The best sample obtained in this study was (AS9), and to find out the suitability of this sample that was selected for paving process, the Marshall, chemical immersion and aging test as well as the field emission scanning electron microscope were performed. The modified sample gave better rheological properties and a resistance greater by 56% than the original asphalt when compared with the standard specifications approved in the field of paving.

Application of Epoxy-Asphalt Composite in Asphalt Paving Industry: A Review with Emphasis on Physicochemical Properties and Pavement Performances

One of the failure mechanisms associated with asphalt paving layers, especially on steel deck bridges, is large permanent deformation, which adversely affects its long-term performance in service. Thus, epoxy resin was introduced in asphalt paving industry to tackle permanent deformation of asphalt mixtures due to its thermosetting nature. In this review, epoxy resin as a dominant component of the epoxy-asphalt composite system was first considered, followed by a discussion on its curing methods and curing mechanism. Furthermore, the physicochemical property and mechanical performance of epoxy asphalt and epoxy asphalt mixture were thoroughly examined. Crosslink density of epoxy asphalt dictates its viscosity and thus the allowable construction time. Phase separation and dispersion of asphalt particles in the epoxy matrix was observed for epoxy-asphalt composite, and it showed superior elastic behavior and deformation resistance capability when compared with conventional asphalt materials. Furthermore, epoxy asphalt mixture exhibited significantly higher compressive strength, much better rutting resistance, and superior durability and water resistance properties. However, its low-temperature cracking resistance was slightly compromised.

Predicting a Model for Modified Asphalt Cement Rutting Parameters

This paper aims to investigate the relationship between the Superpave rutting parameter of asphalt (G﹡/sin δ) by conducting Dynamic Shear Rheometer (DSR) tests with the rut depth values obtained by the wheel track device. The twenty asphalt mixtures have been prepared with twenty types of unmodified asphalts and Polymer-Modified Binders (PMBs). SBS was used to produce PMBs. The twenty base and modified asphalts have been used to prepare asphalt paving mixtures required to conduct wheel track tests. The predicted model of asphalt mixtures rut depth related to asphalt rutting parameter (G﹡/sin δ) values has been founded. Besides, the minimum limits of (G﹡/sin δ) of aged asphalt have been gotten as 3.25 kPa for Iraqi asphalt cement.

Assessment of Asphalt Mixture Behaviour Containing Recycled Concrete Aggregates

Recently, the construction industry uses the Recycled Concrete Aggregates (RCA)resulting from construction and demolition waste (CDW) to achieve sustainable requirements andeconomic benefits. In this paper, asphalt paving mixes were prepared with RCA instead of naturalaggregates for the base course in flexible road pavements and walking areas used by pedestrians andcyclists. Different asphalt mixes samples were prepared with different asphalt contents to meet therequired specifications. Additionally, several laboratory tests were carried out to assess mixturebehavior including the Marshall test. The results indicated that the mixture made with aggregates ofCDW have met all the requirements of Iraqi specifications of roads and bridges (SORB/R9). Thisinvestigation could be a useful guide for road engineers in designing asphalt mixtures from RCA.

RPAS BASED TRACKING OF MACHINERY USED IN ASPHALT PAVING PROCESS

Application of rigorous construction procedures is fundamental when it comes to road construction. Nowadays, and in particular in Chile, the asphalt paving construction process is based on tradition, craftsmanship and other implicit, experience-based methods employed during road construction. This means, that the different stages of the construction process, including the paving of the road, are not controlled on time as they should, which causes that the final product does not have the ideal characteristics for which the construction materials initially were designed and manufactured. Therefore, we propose the use of tools and methodologies that allow monitoring each of the stages of the construction process in almost real-time. Our approach aims to evaluate the use of Remotely Piloted Aircraft Systems (RPAS) during the asphalt pavement construction process by capturing images and videos during the placement of the asphalt mixture and the movement of the compaction machinery (pneumatic roller and drum roller) present in the construction site. The observations are digitally processed by mainly binarization and thresholding. As a result, the macro texture of the asphalt surface was estimated and the trajectory of the compaction rollers was visualized. In conclusion, our results reveal that the main factor that influences the quality of the roads corresponds to the performance and operations of the compaction machinery.