Gyratory Compaction Method Research Articles

Design of High-Modulus Asphalt Concrete for the Middle Layer of Asphalt Pavement

This article investigates the application of high-modulus asphalt mixtures (HMM-13) in the intermediate layer of pavement, addressing rutting issues in asphalt pavements subjected to heavy traffic and high temperatures. The study utilized a 1% dosage of high-modulus modifier, and initially, the mix design of HMM-13 was determined using the gyratory compaction method. Subsequently, this study evaluated the road performance of HMM-13 through tests, including the −10 °C beam bending test, rutting tests at 60 and 70 °C, the freeze–thaw splitting test, and the single-axis compression dynamic modulus test. To ensure the effectiveness of the mixture’s on-site application, this study validated the raw material specifications at the construction site and adjusted the mix design accordingly. Water stability tests were also conducted. Finally, a survey of the mixing plant at the construction site was carried out, establishing the relationship between each bin’s flow rate and speed ratio. The suitable speed for the production of HMM-13 was calculated. The research results indicate that the optimal asphalt-to-aggregate ratio for HMM-13 is 4.2% (with a comprehensive asphalt-to-aggregate ratio of 5.2%), and the freeze–thaw splitting strength ratio can reach 84.2%. The dynamic stability is 11,217 cycles/mm at 60 °C and 6167 cycles/mm at 70 °C. The stiffness modulus at −10 °C is 5438 MPa, with a failure strain of 2049 με. At 10 Hz and 15 °C, the dynamic modulus is 15,488 MPa, and at 45 °C, it is 3872 MPa. All these indicators meet the requirements for construction technology and pavement performance.

The influence of recycled asphalt pavement materials on low and intermediate fracture behavior of asphalt concrete (AC) after exposing to different thawing and freezing periods

The effects of compaction process, mixture type and environmental conditions on mode I cracking resistance of asphalt concrete (AC) materials was investigated experimentally. To do that, a large number of edge notched disc bend specimens containing 0, 25 and 50% recycled asphalt mixture (RAP) material and exposed to different numbers of thawing and freezing cycles (0 to 10 cycles) were fractured. The critical values of stress intensity factor and fracture energy indexes were obtained for the AC mixtures at three test temperatures of −25, 0 and + 25 °C. Based on the results, the fracture resistance capacity of the AC mixture was decreased by increasing the RAP content, number of thawing/freezing cycles and decreasing the test temperature. The effect of thawing/freezing cycles on decreasing the cracking resistance was more pronounced for the first cycles and the variations of fracture toughness and fracture energy values with the numbers of thawing/freezing cycles showed a plateau form for higher numbers of cycles. The fracture curves of the tested samples manufactured using the Gyratory compaction method was upper than the related curves of samples made by Marshall compaction method. The sensitivity of fracture results (i.e., gradient of reduction in the fracture resistance versus freeze/thaw cycles) became low by increasing the test temperature.

Accelerated laboratory evaluation of the effect of deicing condition on fracture characteristics of Silane-based modified asphalt mixtures

Winter maintenance of roads with inappropriate deicers causes much damage to road infrastructures. Researchers have always looked for suitable alternatives to salts or methods to increase the resistance of asphalt mixtures against chloride-based deicers. In this research, an accelerated laboratory method was used to investigate the effect of different deicers on nano-modified silane-based asphalt mixtures. Asphalt mixture samples were made by gyratory compaction method, and after core extraction, they were exposed to moisture and a solution of salt, Calcium Magnesium Acetate (CMA), and Potassium Acetate (KAc) for 96 h at 60 °C. Afterward, their fracture characteristics were measured at low and intermediate temperatures, and the results were statistically analyzed using two-way ANOVA and Tukey test. Statistical analysis showed that although there is no significant difference between the fracture toughness of asphalt mixtures at 0 °C in the presence of distilled water, CMA, and KAc, the reduction in the fracture toughness of samples is much greater in the presence of brine solution so that the fracture toughness of this mixture experienced a 30% reduction compared to the dry sample. Submerging the specimens in the brine solution reduces the resistance of asphalt mixture to cracking at both low and intermediate temperatures, while KAc has the least damaging effect on the fracture toughness of asphalt mixtures. Based on visual inspection and test results, CMA causes additional stress and cracking in asphalt specimens and reduces their resistance to fracture at intermediate temperatures. The silane-based anti-stripper, maintains the fracture toughness of asphalt mixture samples submerged in distilled water and the deicers at 0 °C at almost constant levels but reduces the Jc parameter in all samples. Also, conditioning in the deicers has a greater effect than binder type on the fracture toughness of asphalt mixtures at 0 °C. Besides, there is a strong interaction between binder and deicer type on stress intensity factor, K1c, of asphalt mixtures.

Effect of marshal and gyratory compaction methods on cracking characteristics of hot mix asphalt concrete materials under all three basic modes of fracture

Asphalt mixtures in the laboratory scale studies are often compacted and manufactured using two well-known methods namely gyratory and marshal methods. Due to differences in compaction procedure, employing any of these methods can affect the overall strength and mechanical properties (such as the fracture toughness and cracking resistance) of hot mix asphalt (HMA) materials. Understanding the effect of compaction method on cracking behavior of asphalt mixtures can provide good insights for estimating the long-term performance of pavements and roads. Therefore, in this research the effect of HMA compaction method is studied experimentally on modes I, II and III cracking behavior and fracture toughness values using the edge notch disc bend (ENDB) specimen. In addition, the effect of adding recycled asphalt pavement (RAP) material is also studied on the fracture behavior. Accordingly several HMA mixtures compacted with both marshal and gyratory methods and containing 0 and 50 % RAP material are tested at a fixed low temperature of −25 °C and the corresponding values of KIc, KIIc and KIIIc as well as the work of fracture values under all three basic modes of loading are obtained. The experimental results show the noticeable effects of loading mode, RAP content and compaction method on the fracture behavior of tested HMA materials. In general, adding RAP material reduces the fracture toughness values for all loading modes. However, compaction method has different effects on the fracture toughness values. While the KIc value obtained from gyratory compaction method is higher than the sample made of marshal method, opposite trends are seen for the shear type fracture modes (i.e. KIIc and KIIIc). The tensile mode over shear type mode fracture toughness ratios (KIIc/ KIc and KIIIc/KIc) as well as the effective fracture toughness and effective work of fracture values for the tested HMA mixtures are also presented and analyzed.

Design Method and Evaluation Criteria on Gyratory Compaction Based Cold-Mixed and Cold-Laid Recycled Asphalt Mixture

Cold-mixed recycled asphalt mixture is widely used due to the advantages of good eco-friendliness, resource conservation, and convenient construction. In order to further improve the mixing ratio design theory of cold-mixed recycled mixture, this paper has presented the research on design method and evaluation criteria of cold-mixed and cold-laid recycled asphalt mixture based on gyratory compaction. Research has shown that fine aggregate and mineral powder adhere to asphalt and exist in the form of agglomeration in the Reclaim Asphalt Pavement (RAP), which will cause the gradation of the milling plan material to decay after extraction. According to the viscosity characteristics of cold mixed asphalt, it is recommended that the mixing temperature of the mixture should be greater than 25°C, the compaction of cold-mixed recycled mixtures is easier to achieve by using gyratory compaction method. The paper proposes a test method to determine the optimal asphalt content based on initial strength and sweep test, and proposes a test method for controlling the strength of the mixture by the number of compactions and the forming temperature, establishes evaluation system of initial strength and final strength of cold-mixed recycled mixture, and corrects the evaluation method of high temperature stability and water stability of cold-mixed recycled mixture. The results show that the cold-mixed recycled mixture has low initial strength, insufficient high-temperature stability and water stability. With the volatilization of the diluent, the strength, high temperature stability and water stability of the mixture have been significantly improved.

Fracture Damage Properties of SBS-Modified Asphalt Mixtures Reinforced with Basalt Fiber after Freeze-Thaw Cycles Using the Acoustic Emission Approach

This paper focuses on the fracture damage characteristics of styrene-butadiene-styrene (SBS)-modified SMA-13 specimens with basalt fiber under various freeze-thaw (F-T) cycles. SBS-modified stone mastic asphalt (SMA)-13 specimens with basalt fiber were prepared, first, using the superpave gyratory compaction method. Then, asphalt mixture specimens processed with 0–21 F-T cycles were adopted for the high-temperature compression and low-temperature splitting tests. Meanwhile, the acoustic emission (AE) test was conducted to evaluate the fracture characteristics of the asphalt mixture during loading. The results showed that the AE parameters could effectively reflect the damage fracture characteristics of the asphalt mixture specimen during the high-temperature compression and low-temperature splitting processes. The fracture damage of the asphalt mixture specimens during compression or splitting are classified into three stages based on the variation of the AE signals, i.e., when the load level is below 0.1~0.2 during the first stage and the load level is 0.1–0.9 or 0.2–0.8 during the second stage. The AE signal amplitude and count show clear correlations with the compression and splitting load levels. Meanwhile, the AE signal clarifies the formation, development, and failure of internal damage for the asphalt mixture specimens during the compression and splitting processes. The intensity (value and density) of the AE signal parameters of asphalt mixture decreases with increasing F-T cycles. It is evident that the F-T cycle has a significant adverse effect on the mechanical strength of asphalt mixture, which makes asphalt mixtures more likely to cause early failure.

Field and Laboratory Properties of Roller-Compacted Concrete Pavements

Roller-compacted concrete (RCC) pavements present three primary challenges relative to conventional concrete pavement: mixture design, structural design details, and construction process and verification. An investigation was initiated to reconcile the discrepancy between the field and laboratory properties of RCC pavements because of differences in laboratory mixture design procedures and field construction processes. Four RCC pavement projects in Illinois were selected for field coring along with sampling of RCC constituent materials for replication of the laboratory mixture design. Density measurements of field cores indicated that density decreased with depth into the pavement structure and the relative density at paving-lane joints could be as low as 80%. Statistical differences in compressive strength and fracture properties between field and laboratory samples were observed and result from differences in density. A 4% difference in density between field and laboratory samples resulted in an approximate 45% difference in compressive strength. The reduction in field RCC strength and fracture properties relative to the values obtained in the laboratory will result in decreased slab flexural capacity and field performance. Application of the gyratory compactor demonstrated that it can be used repeatedly to compact most RCC mixtures to similar target densities as the modified Proctor method and field-extracted cores. The gap between field and laboratory properties of RCC can be reduced by application of high-density pavers; improvement in mixture design procedure with the gyratory compaction method; a foundation layer beneath the RCC that is stiffer, thicker, or both; reduced RCC lift thicknesses to achieve specified density; or all of these.

Influence of foaming water content on foam asphalt mixtures

Warm mix asphalt technology using foamed bitumen is being used widely despite the fact that high air void content and poor coating of large aggregate remain major drawbacks require enhancement. This paper manly focuses on the investigation of water content influence on the foamed bitumen and the asphalt mixture. Influence of the water content in combination with compaction temperature has been investigated using gyratory compaction method. AC11N foam asphalt mixture is produced in the lab using lab foamer. Marshall stability and indirect tensile test was used to evaluate the foam asphalt mixture performance. The investigation revealed that the Marshall stability of foam asphalt mixture is highly influenced by compaction temperature compared to water content. Moreover, increasing the water content helps in coating large aggregates when the mixture is produced at low temperature, nevertheless using high water content reduces the Marshall stability to certain extent. In addition the amount of water trapped in the mixture after the mixing process was determined using thermogravimetric analysis. The amount of water remaining in the asphalt mixture is less than 1% relative to the bitumen mass.

Laboratory Mix Design Procedure for Foamed Bitumen Mixtures

The primary objective of this study was to propose a practical and consistent mix design procedure for foamed bitumen mixture (FBM). The main focus of the proposed methodology was the use of the gyratory compaction method. The study maximized the mix design parameters, such as mixing water content (MWC) and compaction effort. The study was initially carried out on FBMs with virgin limestone aggregate without reclaimed asphalt pavement (RAP) material, and a mix design procedure was proposed. The proposed methodology was validated on FBMs with 50% RAP and 75% RAP. Efforts were also made to optimize the foamed bitumen (FB) content in FBMs with and without RAP. Optimum MWC was achieved by optimizing mechanical properties such as indirect tensile stiffness modulus and indirect tensile strength (ITS-dry and ITS-wet). A rational range of 75% to 85% optimum water content was obtained by the modified Proctor test and found to be the optimum range of MWC that gave optimum mechanical properties for FBMs. The study used a gyratory compactor for FBM compaction and found that a unique, mixture-specific number of gyrations that was independent of the FB content could be established. The study also found that the presence of RAP influenced the design's FB content: treating RAP as black rock in FBM mix design was not appropriate.

Optimal polypropylene fiber amount determination by using gyratory compaction, static creep and Marshall stability and flow analyses

Utilizing gyratory compaction technique for the preparation of asphalt specimens with 100mm diameter moulds is an effective and realistic way of pavement laboratory testing. In fact, Marshall compaction is not a suitable way of modelling in situ conditions in the laboratory environment. Therefore, there has to be some means especially for the determination of the optimal addition of modifier amount which is multifilament 3mm polypropylene (PP) fibers in this case for asphalt specimens prepared via gyratory compaction. Mechanical differences of reference and various amounts of PP modified asphalt mixtures were compared using Superpave gyratory compaction method by carrying out static creep tests utilizing Universal testing machine and standard physical properties, Marshall stability and flow analyses. Also, these test results were compared with the results previously obtained for similar sets of asphalt specimens compacted by 50 blows of Marshall hammer. By carrying out extensive analyses, it was not only seen that the utilization of PP fibers improves the physical and mechanical properties of the resultant mixture mainly by improving the permanent deformation resistance, but also the optimal amount of addition of the aforementioned PP fibers was found to be again 5.5‰ by the weight of aggregate which is the same with the previous Marshall compaction test results. Finally, it is proven that the optimal fiber addition is independent of compaction technique which is very important for repeatability and reproducibility of the test results.

Strategic Highway Research Program gyratory compaction for predicting air voids of Saskatchewan SPS-9A asphalt mixes after 10 years of performance in the field

Many Saskatchewan provincial highways exhibit permanent deformation that is mostly attributed to reduction in air voids in hot mix asphalt concrete surfacing. The Saskatchewan Ministry of Highways and Infrastructure (MHI) currently use the Marshall compaction method for hot mix asphalt concrete (HMAC) design and placement quality control and quality assurance. It has been found that the Marshall compaction method does not accurately predict field air voids. Therefore, MHI identified the need to evaluate the SuperpaveTM gyratory compaction method to predict field air voids of typical Saskatchewan asphalt mixes. This paper presents a summary of laboratory and field volumetric as well as rapid triaxial mechanistic material properties of typical Saskatchewan asphalt mixes. This research considered seven asphalt mixes from the Radisson Specific Pavement Study (SPS)-9A test site comprising two conventional Saskatchewan Marshall Type 71 mixes, five SuperpaveTM mixes, and a SuperpaveTM recycled mix. This research determined that Marshall compaction and the gyratory compaction at 1.25° gyration angle underestimate the collapse of field air voids. This research also showed that the gyratory compaction method at 2.00° angle of gyration more accurately predicted field air voids of the asphalt mixes constructed as part of test site.

The Study of the Effect of Temperature, Binder Content and Compaction on Resilient Modulus of HMA

In this study, the effect of temperature, binder content and compaction on the resilient modulus of hot mix asphalt (HMA) were studied. The samples were prepared by using gyratory compaction method. The resilient modulus of samples that were prepared with different binder content and compaction effort were determined by Indirect Tensile Method (ASTM – D4123). To increase the accuracy, the tests were conducted on two similar samples and the results were discussed by using both tests. The results show that with increasing temperature, decreasing binder content and increasing compaction effort, the resilient modulus of hot mix asphalt increase. Based on the results of this study, the variation of resilient modulus with temperature, binder content and gyration number was estimated by using a mathematical model. Comparison of the prediction of this model with experimental results shows that the model is acceptable.

Design method and performance for large stone porous asphalt mixtures

Design method for large stone porous asphalt mixtures (LSPM) was analyzed to avoid the early distresses of semi-rigid asphalt pavements. Based on stone-to-stone skeleton structure concept, processes of LSPM gradation design was given. The gradation composite design for LSPM shows that the LSPM nominal maximum size (NMS) should be larger than 26.5 mm, and the NMS sieve passing percentage should be greater than 50%. Through experiments and calculations on the volume properties of the aggregate, the range of aggregate gradation curve of LSPM was given. In terms of asphalt binder’s normalized test results, MAC-70 and SBS modified asphalt were selected as the asphalt binders. The applicability of large scale Marshall Method and gyratory compaction method to shape specimens was investigated. Based on the asphalt mixture performance evaluation, the optimum asphalt content range (3.1%–3.6%), the bitumen film’s thickness range (13–16 μm) and the air void range (135–18%) were recommended. Finally, LSPM was tested by the laboratory performance tests including rutting resistance test, fatigue test and water stability test. The theoretic and practical analysis shows that LSPM has a good performance on water permeability, rutting resistance and reflection crack resistance.

Some Characteristics of Foamed Bitumen Mixes

A study was conducted at the School of Engineering of Griffith University on characterization of a range of foamed bitumen stabilized mixes in the laboratory. Marshall and servo-controlled gyratory compactors were used in specimen preparation. A closed-loop, servo-controlled dynamic loading system was utilized to determine the resilient modulus. It was found that the Marshall compaction method produced higher resilient modulus values compared with the gyratory compaction method. Moreover, Marshall compaction showed an optimum bitumen content associated with the maximum density. The gyratory compactor produced specimens that were less dependent on bitumen content but had higher density values. The temperature used to cure the specimens was also examined. An accelerated curing temperature of 60°C was found to be too high, resulting in an over-estimation of the resilient modulus compared with specimens cured at an ambient temperature. Furthermore, the resilience test results also showed that the resilient modulus was significantly affected by the applied strain; with higher strain, a lower modulus resulted. Because of its relatively low bitumen content and use of lime additive, the resilient modulus of foamed bitumen mixes is affected by temperature variation less than that of typical hot-mix asphalt concrete mixes.