Panneer (2016) during the study of transition from Marshall

Panneer (2016) during the study of transition from Marshall to Superpave Mix Design evaluated the performance of both methods. The Marshall method of mix design had been used for many years and those pavements have performed well, however, with increased traffic and heavier axle loads, it was decided that an improved method of design was needed. The Superpave mix design method was developed to fill this need. A Superpave design system implemented at three levels. The level one method relied totally on volumetric analysis to determine mix proportions. The other levels of Superpave analyses require complex equipment and have not been implemented. The purpose of any asphalt mix design method is to determine the optimum proportions of aggregate and asphalt cement to be used in an asphalt pavement mix. Two empirical mix designs methods are traditionally used. These are Marshall and Hveem Methods. Superpave method developed by the Strategic Highway Research Program (SHRP), is being considered for full implementation as a design method. The main advantage of Superpave over currently used mix design methods is that it is performance-based method that implies a direct relationship between Laboratory analysis and field performance after construction. Other design methods are empirical and therefore cannot accurately predict how a pavement will perform after construction. Juaidah (2014) evaluated permanent deformation of Superpave and Marshall Mix using SPT Dynamic Modulus Test. The low VMA (Voids in Mineral Aggregates) of Superpave mixes can generally be contributed to the increased compactive effort by Superpave gyratory compactor. This has led to the increased use of coarser asphalt mixes (gradations near the lower control points). The inference made was the minimum VMA requirements in Superpave volumetric mix design for these coarse mixes are the same as those developed for the dense mixes designed by the Marshall method. Di Mino (2007) conducted a research on the volumetric mix-design of porous asphalt. The Superpave mix-design of asphalt mixtures using the gyratory compactor is a procedure used to define the proportion of materials on the basis of specific volumetric parameters. In Superpave, the number of gyrations, Ndesign, is important because it represents the compactive effort that produces a test sample with voids properties similar to those that the same mix would experience in the field. Aravind (2009) evaluated the hot recycled mix asphalt for the determination of its optimal proportioning under Superpave mix design technique. Increased traffic, axle loads and tire pressures, coupled with limited financial resources have resulted in commonly occurring overstressed asphalt pavements. These conditions have forced asphalt engineers and researchers to reconsider the current mix design approaches. The proper selection of the aggregates and the asphalt binder can improve pavement performance, depending upon the environmental and traffic conditions to which the pavement is exposed. However, the asphalt concrete mix will not perform as required if the proper compaction procedure is not followed. Alani (2010) selected Fifteen Hveem mix designs from around the state that are often used in their region were used as the basis of this study. The 15 selected mix designs vary in binder Performance Grading (PG-grade), binder type (unmodified, rubber, and polymer), aggregate gradation and mineralogy, and Reclaimed Asphalt Pavement (RAP) percentage. Based on the Hveem mix designs, Superpave volumetric mix designs were developed for each mix and comparisons were made between mixes developed from both methods. Specifically, the mixes were evaluated to meet the draft Caltrans Superpave volumetric mix design specification which includes the design air-void content, percent VMA, percent VFA (Voids Filled with Asphalt binder) and dust proportion as major design components.Zaynab (2017) evaluated the performance of different aggregate-asphalt binder blends. The Superpave method, like other mix design methods, creates several trial aggregate-asphalt binder blends, each with different asphalt binder content. Then, by evaluating each trial blend’s performance, optimum asphalt binder content can be selected.Cooley (2007) said that the trial blends must contain a range of asphalt contents both above and below the optimum asphalt content. Therefore, the first step in sample preparation is to estimate optimum asphalt content. Trial blend asphalt contents are then determined from this estimate. The Superpave gyratory compactor was developed to improve mix design’s ability to simulate actual field compaction particle orientation with laboratory equipment.Al-Mistarehi (2014) did a research on calculating design number of gyrations. Each sample is heated to the anticipated mixing temperature, aged for a short time (up to 4 hours) and compacted with the gyratory compactor, a device that applies pressure to a sample through a hydraulically or mechanically operated load. Mixing and compaction temperatures are chosen according to asphalt binder properties so that compaction occurs at the same viscosity level for different mixes. Key parameters of the gyratory compactor are: ? Sample size = 150 mm (6-inch) diameter cylinder and 115 mm (4.5 inches) in height.? Load = Flat and circular with a diameter of 149.5 mm (5.89 inches) and area of 175.5 cm2 (27.24in2).? Compaction pressure = Typically 600 KPa (87 psi).? Number of blows = varies.? Simulation method = the load is applied to the sample top and covers almost the entire sample top area. The sample is inclined at 1.25o and rotates at 30 revolutions per minute as the load is continuously applied. This helps achieve a sample particle orientation that is somewhat like that achieved in the field after roller compaction.Panneer (2016) studied the effect of compaction method on the performance of HMA. Superpave Gyratory Compactor was used to find the design number of gyrations. The Superpave gyratory compactor establishes three different gyration numbers:1. Ninitial. The number of gyrations used as a measure of mixture compactability during construction. Mixes that compact too quickly (air voids at Ninitial are too low) may be tender during construction and unstable when subjected to traffic. Often, this is a good indication of aggregate quality – HMA with excess natural sand will frequently fail the Ninitial requirement. A mixture designed for greater than or equal to 3 million ESALs with 4 percent air voids at Ndesign should have at least 11 percent air voids at Ninitial.2. Ndesign. This is the design number of gyrations required to produce a sample with the same density as that expected in the field after the indicated amount of traffic. A mix with 4 percent air voids at Ndesign is desired in mix design.3. Nmax. The number of gyrations required to produce a laboratory density that should never be exceeded in the field. If the air voids at Nmax are too low, then the field mixture may compact too much under traffic resulting in excessively low air voids and potential rutting. The air void content at Nmax should never be below 2 percent air voids.Ahmad (2014) used local materials to find their suitability for performance based evaluation and performed different tests to determine their resistance against rutting. The local material satisfies the Superpave consensus and source aggregate properties criteria and is therefore suitable for use in the Superpave system. Superpave-designed mixtures are more superior and least susceptible to permanent deformation compared to Marshall-designed mixtures based on pavement performance tests. The Simple Performance Test (SPT) dynamic modulus test has the potential to replace the resilient modulus test, wheel tracking test, dynamic creep test to evaluate rutting deformation. Rutting can be better performed using the SPT dynamic modulus test and most of the correlations between these tests are moderate to strong which indicates that the SPT dynamic modulus test is viable and reliable in predicting rutting performance. As such, a large amount of specimen fabrication can be minimized to be used for different testing methods. Therefore, the dynamic modulus test is highly recommended for Superpave mixture characterization under tropical climatic conditions since this test provides full characterization of the mix over a broad range of temperatures and loading frequencies.To investigate the performance characteristics of Superpave and Marshall Method design HMA mixtures in tropical climatic conditions. Laboratory tests were conducted to evaluate the rutting (permanent deformation) and resilient modulus of different Superpave and Marshall mixes. In addition, dynamic modulus tests by means of the Simple Performance Test (SPT) were also conducted. The relationships between the SPT dynamic modulus test and other performance test results were also examined. It was found that the Superpave-mix design showed far superior performance compared to the Marshall-mix design based on all types of testing in this study. Since the dynamic modulus test provides full characterization of the mix over a broad range of temperatures and loading frequencies, this test is highly recommended for Superpave mixture characterization under tropical climatic conditions. Ibrahim (2012) conducted in Taiwan to compare the volumetric and mechanical performance properties of Superpave mixtures and Typical Taiwan Mixtures (TTM) using the Marshall method. It was found that the binder contents of the Superpave-designed mixtures are lower than the TTM Marshall-designed mixtures. It was found that the Superpave mix design procedure recommended, for the local environmental and loading conditions, lower asphalt content than that predicted by Marshall Mix design procedure. In addition, it was found that using the presently recommended local aggregate gradation for heavy traffic in the Superpave design method gave dust proportion higher than the maximum specified limit by the Superpave procedure. High dust proportion will usually lead to brittleness of the mixes. Therefore, shifting to the Superpave design procedure might help in solving the bleeding problem and some of the distresses common in the local asphalt structures.Aziz (2012) studied the volumetric characteristics of Hot Mix Asphalt (HMA) samples which were prepared using Superpave Gyratory Compactor (SGC). Superpave uses volumetric analysis for the mix design and follows three major steps in the testing and analysis process. The unique feature of Superpave system is that it is a performance-based specification. The tests and analysis have direct relationships to field performance. The Superpave mix design procedure involves selecting of asphalt and aggregate materials that meet the Superpave specifications and then conducting a volumetric analysis of mix specimen compacted with the Superpave gyratory compactor.Zumrawi (2016) did a research on the compaction method of HMA samples preparation. During this research, the impact of using Gyratory compactor on the performance of HMA was studied. The Gyratory Testing Machine (GTM) developed by US Corps of Engineers. This machine has the capability to compact HMA mixtures using a kneading process that simulates the action of rollers during construction. The GTM was operated at vertical pressure of 8.2 kg/cm2, which was approximately equal to the truck tyre inflation pressures, the gyration angle degree and 300 revolutions. The GTM can be used for achieving the ultimate density is obtained in the actual field. It was observed that the design asphalt content for Superpave and Marshall Mixes were found to be 5.3 and 5.5 percent (by weight of mix) respectively. It was concluded that, higher density in Superpave is due to Superpave Gyration Compactor compactive effort. From the study it was concluded that, performance based Superpave mixes performed better than Marshall Mixes.