Aggregate-Bitumen Interface Enhancement Mechanism of Utilization of Oil Shale Waste as Fine Aggregate in Open Grade Friction Course

Meng

et al. 2020

Materials

Rutting has always been considered the main disease in asphalt pavement. Dealing with rutting disease would be benefitted by understanding the formation of rutting and testing the rutting performance of mixtures more reasonably. The objective of this paper is to systematically investigate the rutting mechanism by employing a self-designed rutting tester along with the corresponding numerical simulations. The deformation of different positions of the existing tracking tester was found to be inconsistent, and the loading was not in line with reality. Accordingly, a more practical tester was proposed: the reduced scale circular tracking (RSCT) tester integrates the functions of asphalt mixture fabrication and rutting monitoring. The results demonstrated that the loading of the new tester is closer to the actual situation. In addition, determining the stress and displacement characteristics of particles in the asphalt mixture was found to be difficult due to the limitations of the testing methods. Therefore, a two-dimensional virtual rutting test based on the RSCT was built using PFC2D (Particle Flow Code 2 Dimension) to investigate the mechanism of formation in rutting and to obtain the corresponding guidance. The numerical simulation showed that all particles of the specimen tended to move away from the load location. The main cause of rutting formation was the eddy current flow of asphalt mastic driven by coarse aggregates. The aggregates with diameters ranging from 9.5 to 4.75 mm were observed to have the greatest contribution to rutting deformation. Therefore, the aggregate amount of these spans should be focused on in the design of mixture grading.

Section: Basic Assumptionsmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Investigation on the Micro Deformation Mechanism of Asphalt Mixtures under High Temperatures Based on a Self-Developed Laboratory Test

Meng

et al. 2020

Materials

“…After magnifying observation, it was found that the surface of oil shale waste is rough, that oil shale waste has a large number of micron-sized pores, and the edge of the pores is surrounded by mossy and petal-like protrusions. Such a unique microscopic appearance can achieve a larger bonding area when combined with asphalt, reduce the content of surplus asphalt, and effectively reshape the combination mode of asphalt and aggregate [37].…”

Section: Oil Shale Wastementioning

confidence: 99%

“…In a previous study, in order to determine a promising solution to minimize environmental pollution by sinking the accumulation of waste materials and improve the strength durability of permeable pavement, a novel OGFC material, named COF-OGFC, using oil shale waste as a fine aggregate in OGFC, was designed to meet the requirements of sponge city construction in Siping City (Jilin province, China). The test results showed that the overall properties of COF-OGFC were about 30% better than those of a conventional asphalt mixture, and it could effectively reduce construction costs and environmental pollution by industrial waste [37,38]. However, the permeability durability when using oil shale waste as a fine aggregate in OGFC in seasonal frozen regions is unclear.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Evaluation of the Permeability Durability of Utilization of Oil Shale Waste as Fine Aggregate in Open Grade Friction Course in Seasonal Frozen Regions

Chen

et al. 2020

Applied Sciences

Open graded friction course (OGFC), as a highly permeable mixture, has the characteristics of good friction and splash-and-spray reduction during rainstorms. The limitations of the use of such mixtures include the fact that they are affected by poor durability, including strength and permeability durability issues. In a previous study, oil shale waste, as a fine aggregate in the mixture (with a particle size less than 4.75 mm), could effectively improve the overall properties of OGFC, but the permeability durability was not clear. Thus, a comprehensive investigation of the permeability durability of oil shale waste as a fine aggregate is essential to achieving a better understanding in order to promote its engineering application. In this paper, the long-term permeability when using oil shale waste as a fine aggregate in OGFC was systematically investigated based on a self-developed laboratory physical clogging procedure. The test results illustrated the effectiveness of the utilization of oil shale waste as a fine aggregate in terms of permeability durability. A comprehensive index of the clogging coefficient containing mass, porosity and permeability coefficient was proposed based on gray relation entropy theory, the physical clogging model of COF-OGFC (OGFC containing oil shale waste filler) was established and the clogging speed of COF-OGFC was quantified based on the Mistcherlich growth model. The analysis showed that there is an essential difference in the clogging behavior of permeable pavement in the spring and summer. The maximum clogging degree of the permeable pavement in summer is about 40% higher than that in spring, while the clogging rate is much lower than in the spring, at only about 14%, which indicates that the clogging behavior of permeable asphalt pavement in spring is mostly in the rapid clogging mode, and that in summer is mostly in a slow deposition clogging mode. Moreover, the test results showed that the most important influences on the spring clogging behavior of COF-OGFC were the sandy clogging materials and particle sizes ranging from 150 μm to 1180 μm, which can be used to provide a reference for the design of anti-slip sand.

“…Asphalt pavement is the most widely used advanced pavement in global pavement construction due to the special properties such as low noise, high comfort and strong repairability [1][2][3]. More than 94% of the 2.7 million miles of paved roads in the United States are surfaced with asphalt [4,5].…”

Section: Introductionmentioning

confidence: 99%

Laboratory Investigation on Physical, Rheological Thermal and Microscopic Characteristics of Water-Foamed Asphalt under Three Environmental Conditions

Li³

et al. 2020

Coatings

Applications of water-foamed binders have received widespread attention due to its environmental and economic benefits. This study aims to evaluate the properties of water-foamed asphalt under three environmental conditions (high-temperature evaporation, low-temperature frozen and the freeze–thaw cycle). Conventional physical properties tests, dynamic shear rheometer test (DSR), differential scanning calorimetry test (DSC) and scanning electron microscope test (SEM) are employed to assess the physical, rheological thermal and microscopic characteristics of samples. Conventional physical properties test results showed that the performance of a foamed binder had declined under three environmental processes and the foamed asphalt gradually returned to the characteristics before being foamed, with the increase of process time. A comprehensive evaluation index, deterioration degree was proposed based on the test results and entropy theory, and the deterioration process of the foamed binder under three environmental conditions was quantified. Moreover, freeze–thaw (F–T) cycles had been proved to have the most significant influence on the performance of a foamed binder among three environmental factors, which was a key issue that limits the application and promotion of foamed asphalt in seasonal frozen regions. The DSR test showed that the resistance to high-temperature permanent deformation of the foamed binder was improved after F–T cycles, and the fatigue resistance became worse. The sensitivity analysis of complex modulus and frequency illustrated that foamed asphalt after F–T cycles were more sensitive to the loading frequency and less sensitive to the temperature. The DSC test indicated that the thermal stability of foamed asphalt was improved after F–T cycles. The disappearance of circular “cavitation” observed through SEM test revealed that moisture of foamed asphalt was gradually precipitated and self-healing phenomenon occurred during F–T cycles.