Number Of Gyrations Research Articles

Influence of the Compaction Method on Mineral-Cement Emulsion Mixture Properties

AbstractThe present study describes the reuse of mineral-cement emulsion (MCE) mixtures from old and damaged pavements. Different recycling and compaction methods are presented and evaluated using strength tests to find the optimal composition. Marshall, gyratory, and static compaction methods were used and the results were analyzed. The methodology included measurements of Marshall stability and flow, compressive strength, frost resistance, and air void content. Analysis of the results showed a strong correlation between the compaction method used and the final result. The data show that a comparison of compaction methods is possible only when the methods are modified appropriately and the corresponding adjustments of MCE mixtures were proposed. The modifications included variations in compaction conditions. The optimal number of gyrations and the minimal height of the specimen were determined as a recommendation for future comparison with the Marshall method. Tests of the MCE mixtures showed that by imp...

Performance Characteristics Comparisons of Various Asphalt Mixture Technologies

Abstract A laboratory investigation was carried out to study the effects of various compaction technologies on moisture susceptibility, rutting resistance, and fatigue characteristics of various asphalt mixtures. The methodologies used in this study included three technologies such as common hot mix asphalt (HMA), warm mix (WMA), and half-warm mix asphalt (HWMA) technologies. In addition, in terms of WMA and HWMA mixtures, a foaming technology was used to produce the samples. The experimental design for WMA and HWMA included one aggregate moisture contents (∼0.5 % by weight of the dry mass of the aggregate), three lime contents (0 %, 1 % and 2 % lime by weight of dry aggregate), and 2 % foaming water content. For HMA, 1 % lime content and completely dried aggregate were used. Three aggregate sources (designated as A, B, and C) and one PG 64-22 binder were used in this study. A total of 9 Superpave mix designs and 21 mixtures were completed. A total of 84 indirect tensile strength (ITS) samples, 126 asphalt pavement analyzer (APA) samples, and 30 fatigue beams were tested in this research. The major properties such as gyration number, ITS, tensile strength ratio (TSR), rut depth, deformation, toughness, as well as fatigue life were measured and computed for all mixtures. The test results indicated that various compaction technologies would slightly affect the Superpave mix design and obviously have an influence on gyration number, ITS values, rut depth, flow, toughness, and fatigue life of various mixtures regardless of aggregate source and lime content. In addition, the aggregate source significantly affected the ITS and rutting resistance in this study.

Laboratory characterization of compaction and damping properties of Stone Matrix Asphalt

Stone Matrix Asphalt (SMA) is referred to gap graded Hot Mix Asphalt (HMA) that is designed to maximize rutting resistance and durability by using a structural basis of stone-on-stone contact. SMA mixture designs with gap graded aggregate gradations and polymer modified binders often have special field compaction requirements. To better understand differences in compaction behavior between SMA and dense graded HMA mixtures, laboratory tests were conducted on field collected loose samples at typical field densities and loading conditions. The goal of the first phase of this study was to investigate the growth of density and the mobilized shear stress in the specimen as a function of applied normal stress, gyration numbers, and the compactive effort. In the second phase, damping ratio tests were performed on the compacted samples at close to field compaction temperatures by applying dynamic loading at various frequencies and different confining pressures to determine the mixture damping properties. The test results indicated that SMA mixtures with the gap graded aggregate structure achieved higher densities in comparison to HMA mixtures. The frequency of dynamic loading had a significant effect on the damping ratios of the SMA mixtures and the effect of confining pressure, linked to proper lift thicknesses in the field, was found to be dependent on compaction pressure levels as well as mixture properties.

Characterizing Compactability of High RAP and Warm Mix Asphalt Mixtures in the Superpave Gyratory Compactor.

Abstract Compactability of asphalt concrete mixtures is critical for successful long-term performance in the field. Laboratory samples are necessary for volumetric analysis and performance testing during the design process, so the ability to quantify compactability during specimen production in the lab would be highly beneficial. While there has been significant work in defining compaction characteristics of asphalt concrete, most of this work has revolved around traditional Hot Mix Asphalt (HMA), and little work has been done with Warm Mix Asphalt (WMA) or high percentage Recycled Asphalt Pavement (RAP) mixtures. This research examined HMA without RAP (HMA Virgin), HMA with 35 % RAP (HMA RAP), and two WMA technologies with 35 % RAP (WMA 1 and WMA 2). Four compactability metrics were evaluated, including number of gyrations to 92 % density (N92), Construction Densification Index (CDI), the Construction Force Index (CFI), and the newly introduced Normalized Shear Index (NSI). This research found that the WMA technologies improved the compactability of asphalt concrete, as did the addition of RAP. In general, the WMA 1 showed better compactability than WMA 2, but this could be partially attributed to a softer binder grade, higher asphalt binder content, and the potential for a tender mix, as indicated by the normalized shear curve. The HMA RAP mixture also had a higher asphalt binder content compared to HMA Virgin, which could have contributed to the improved compactability. The NSI metric consistently showed the lowest Coefficient of Variation (COV) values and has the potential to distinguish tender mixtures.

Cold In-Place Recycling as a Sustainable Pavement Practice

Pavement rehabilitation and reconstruction methods with CIR (cold in-place recycling) are alternatives that can effectively reduce the high stresses and waste produced by conventional pavement strategies. An attempt was made to predict the performance, particularly low-temperature cracking resistance characteristics of CIR mixtures. These were prepared with the mix design procedure developed at the URI (University of Rhode Island) for the FHW A (Federal Highway Administration) to reduce wide variations in the application ofCIR mixtures production. This standard was applied to RAP (reclaimed asphalt pavement) to produce CIR mixtures with CSS-lh asphalt emulsion as the additive. By adjusting the number of gyrations of the SGC (Superpave gyratory compactor) for compaction, the field density of 130 pcf was represented accurately. To secure a base line, HMA (hot mix asphalt) samples were produced according to the Superpave volumetric mix design procedure. The specimens were tested using the IDT (indirect tensile) tester according to the procedure of AASHTO T 322 procedure at temperatures of -20, -10 and 0 °C ( -4, 14, and 32 Gp, respectively). The obtained results for the creep compliance and tensile strength were used as input data for the MEPDG (mechanistic empirical pavement design gnide ). The analysis results indicated that no thermal or low-temperature cracking is expected over the entire analysis period of 20 years for both HMA and CIR mixtures. Thus, it appears that CIR is a sustainable rehabilitation technique which is also suitable for colder climates, and it is reconunended to conduct further investigation ofload-related distresses such as rotting and fatigue cracking.

Feasibility Research on Superpave Gyratory Compactor Method Design Mix of Stone Mastic Asphalt

This paper analyzed the limitation of the stone mastic asphalt (SMA) mixture designing methods in China, then the Superpave Gyratory Compactor(SGC) method for SMA mixture where designing applicable and feasibility was analyzed, and SGC method was introduced to promote the application in SMA mixture design. It is found that the compaction work determined by the SGC design procedure was remarkably increased compared to that by Marshall design when the number of gyrations is 100. It is recommended that the number of gyrations should be decreased instead of 100 when SGC is used to design SMA mixture in China.

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.

A Performance-based Evaluation of Superpave Design Gyrations for High Traffic Surface Mixes

The number of design gyrations (Ndes) is an extremely important parameter in the asphalt concrete mix design procedure using the Superpave method. The choice of Ndes is a function of total traffic during the pavement service life, expressed in ESALs. Asphalt concrete mixes for higher traffic levels are compacted to a higher Ndes as a denser mix resists rutting more effectively. However, this leads to a lower design asphalt content, which decreases fatigue performance of the mix. Therefore, a performance-oriented approach to determine Ndes was developed that optimizes mix performance with respect to both rutting and fatigue cracking.In this paper, the research methodology adopted to compare the relative performance of surface mixes with 12.5mm nominal maximum aggregate size is presented, along with recommended Ndes values for C and D-level mixes, designed to handle traffic levels of 3-30 Million and greater than 30 Million ESALs, respectively. Asphalt concrete mixes were designed at Ndes levels of 50, 75, 100 and 125 gyrations to determine asphalt content using Superpave design method. Dynamic modulus (E*) was measured at design asphalt content for different gyration levels using the Asphalt Mixture Performance Tester device. The E* data and corresponding binder properties were used as input in the AASHTO Darwin-ME software to predict rutting and fatigue performance of the mixes by assuming a model pavement section and appropriate traffic levels. Relative performance indicators were developed for both rutting and fatigue, and plotted against the asphalt content to determine optimum Ndes. For both surface mixes, the optimum Ndes value was determined to be 85 gyrations.

An artificial neural network model for virtual Superpave asphalt mixture design

This study presents an artificial neural network (ANN) model to predict the asphalt mixture volumetrics at Superpave gyration levels. The input data-set needed by the algorithm is composed of gradation of the mix, bulk specific gravity of aggregates, low- and high-performance grade of the binder, binder content of the mix and the target number of gyrations (i.e. Nini, Ndes and Nmax). The proposed ANN model uses a three-layer scaled conjugate gradient back-propagation (feed-forward) network. The ANN was trained using data obtained from numerous roads with a total of 1817 different mix designs. Results revealed that the ANN was able to predict Va within Va (measured) ± 1.0% range 85–93% of the time and within Va (measured) ± 0.5% range 60–70% of the time. Currently with the developed ANN model, Superpave mix design can take approximately between 1.5 and 4.5 days, which corresponds to 3–6 days of savings.

Rutting analysis of 100 mm diameter polypropylene modified asphalt specimens using gyratory and Marshall compactors

Compaction technique used in Marshall design does not model the process of actual rolling procedures on site exactly. Carrying out laboratory compaction of dense bituminous mixtures with Superpave gyratory compactors is a more realistic way of simulating actual compaction. In this study, mechanical differences of reference and polypropylene modified asphalt mixtures were compared using Superpave gyratory and Marshall compaction methods by carrying out repeated creep tests utilising universal testing machine. In addition, there is no standard Superpave design procedure for 100 mm diameter samples till date. The other purpose of this study is to propose new standards for the compaction and testing procedures of these 100 mm specimens. Indeed, extensive studies have shown that the design gyration number should be 40 for reference and 33 for polypropylene modified specimens under medium traffic conditions for the similar and specific type of aggregate sources, bitumen, aggregate gradation, mix proportioning, modification technique and laboratory conditions. Moreover, it was shown that, the asphalt samples produced by Superpave gyratory compactor were much resistant to destructive rutting effects than the asphalt specimens prepared by Marshall design.

Development of a gyratory compaction procedure for laterite gravels treated with foamed bitumen

Determining of the optimum density of the compacted foamed bitumen-treated materials is an important part of determining the field placement conditions. Laterite gravels tend to be highly susceptible to breakdown during laboratory compaction with the standard Proctor hammer, which may not be representative of field conditions. In this paper, a new method is presented for determining the optimal compaction characteristics of laterite gravels–foamed bitumen mixes. A gyratory compactor was used for compaction. The modified locking point concept was used to determine the number of gyrations to compact mixes of laterite gravels and foamed bitumen. The optimal compaction moisture content was subsequently established at this point. The average number of gyrations that gave the locking point was 44; optimum moisture content (OMC) for compaction varied from 86% to 92% for gravels only. The modified locking point seems to be suitable for determining the optimal compaction characteristics of these mixes.

Performance Characterization of Asphalt Mixtures at High Asphalt Binder Replacement with Recycled Asphalt Shingles

Recycled materials can be used effectively in asphalt mixtures to replace virgin asphalt binder or virgin aggregates. Virgin material (asphalt binder or aggregate) can be replaced with reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in asphalt mixtures. The study presented in this paper examined the effect of high asphalt binder replacement (ABR) for an asphalt mixture with a low number of design gyrations (a low N-design) and RAP and RAS on performance indicators (e.g., permanent deformation, fracture, fatigue potentials, stiffness). A developed experimental program included complex modulus, fracture, overlay reflective cracking resistance, low-temperature cracking, wheel track permanent deformations, and push–pull fatigue tests. The ABR, combinations of RAS and RAP asphalt binder, and levels in the mix ranged from 43% to 64%. Potential permanent deformation resistance of the mixtures was improved in the presence of RAS. Fracture tests at low temperature revealed no significant difference between the specimens prepared at varying percentages of ABR. Fatigue potential of mixtures increased with an increase in RAS content and ABR. The specimens prepared with 2.5% RAS and PG 46-34 showed the best fatigue potential performance. The impact of asphalt binder bumping was highlighted by the results of all tests. The improvement in fatigue life and fracture energy was noticeable when the asphalt binder type was changed from PG 58-28 to PG 46-34 at the highest ABR level. The complex modulus test results can provide crucial information about the mix viscoelastic properties, such as relaxation potential and long-term stiffness. These results can be used, along with fracture test results, to evaluate mix brittleness at relatively high ABR levels.

Application of discrete element method to Superpave gyratory compaction

Superpave mix design method is one of the major asphalt mixture design methods and has been widely used worldwide. However, the Superpave laboratory mix design process is time-consuming and requires significant human and material resources. In this study, the discrete element method (DEM) was used to simulate the compaction of hot-mix asphalt (HMA) with the Superpave gyratory compactor (SGC). The open source DEM code, YADE, was modified and implemented with C++programming language to conduct virtual SGC compaction. The effects of aggregate gradation, gyration number, gyration angle, and parameters of contact model during the SGC compaction were investigated. Also, the clump technique was utilised to study the effect of aggregate shape. To verify the DEM simulation results, a laboratory SGC compaction was conducted. The results from the DEM virtual compaction were generally in agreement with the experimental data, indicating that DEM provides a feasible way to simulate asphalt mixture compaction. With further research, DEM has the potential to be a helpful tool for aggregate selection in asphalt mix design.

Laboratory investigation of compaction characteristics and performance of warm mix asphalt containing chemical additives

This paper focuses on the compaction characteristics and performance of warm mix asphalt containing chemical additive. Viscosity tests indicated the used chemical additive had a limited effect on viscosity reduction. Investigation into the ease of compaction showed that asphalt mixtures containing 2% chemical additive allowed compacting at lower temperatures and mixture compactability was less dependent on bitumen viscosity. It was demonstrated that the compactability of warm mix asphalt could be well ranked by using various indicators including the number of gyrations to achieve a design void content, the slope of accumulated compaction energy against the number of gyrations as well as compaction energy indices at various compaction phases. Data obtained from immersion wheel tracking tests indicated that warm mix asphalt containing chemical additive did not have a performance comparable to that of hot mix asphalt. Rutting and stripping were found to be the main causes resulting in poor performance.

Effect of Compaction Temperature on Rutting and Moisture Resistance of Foamed Warm-Mix-Asphalt Mixtures

AbstractA laboratory investigation was carried out to study the effects of various compaction temperatures on moisture susceptibility and rutting resistance of warm-mix-asphalt (WMA) mixtures containing moist aggregates using a foaming technology. The experimental design included two aggregate moisture contents (0 and ∼0.5% by weight of aggregate dry mass), one lime content (1% lime by weight of dry aggregate), two foaming water contents (2 and 3%) with control, and two aggregate sources. The major properties, such as the gyration number of various samples, indirect tensile strength (ITS), tensile strength ratio, rut depths of dry and conditioned specimens, and deformation (flow), were measured for all mixtures. The test results indicated that the aggregate source significantly affected the ITS and rutting resistance regardless of the foaming water content, compaction temperature, and aggregate moisture content. In addition, mixtures from moist aggregate had lower gyration numbers regardless of aggregate ...

Numerical Simulation of a Helical Pipe Coalescence Device

A model of coalescing helical pipe is established through the analysis to the oil phase in continuous water phase inside a helical pipe, by using Fluent software. The influence of structural parameters and operation parameters of helical pipes on oil droplet coalescing effect is verified. Results show that the oil drop coalescing effect increases with the rise of gyration radius and number of turns of helical pipe, and decreases with the rise of the helical pipe diameter and inlet velocity.

Criteria for using the Superpave gyratory compactor to design airport HMA mixtures

Asphalt concrete pavements for commercial airport applications in the USA are constructed according to guidelines in Item P-401, ‘Plant Mix Bituminous Pavements’, Federal Aviation Administration (FAA) Advisory Circular 150/5370-10E. Item P-401 specifies the material characteristics and construction requirements for airport asphalt pavements, but does not currently provide guidance for using the Superpave gyratory compactor (SGC) in the preparation of specimens used in the design of hot mix asphalt (HMA) mixtures. Nearly all state departments of transportation in the USA use the SGC along with the Superpave mix design procedure. Since most HMA mixes are used in roadways, many asphalt contractors no longer maintain expertise and equipment for conducting the Marshall mix design procedure currently used by the FAA. The lack of contractors familiar with the Marshall method may become a significant problem for the FAA in the future. This paper describes a laboratory study of the HMA mix design for airport pavements, which uses the SGC. The purpose of the study was to determine the number of gyrations with the SGC needed to design asphalt pavement mixtures for airports. A value of 70 gyrations is recommended for further evaluations based on the comparisons of volumetric measurements of HMA mixture specimens compacted using Marshall compaction with specimens from the same mixture compacted using Superpave gyratory compaction.

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.

HMA와 WMA 혼합물의 선회 다짐횟수 적정성 검토 연구

본 연구에서는 국토해양부 기준으로 제시된 선회 다짐횟수를 가열아스팔트 혼합물과 중온아스팔트 혼합물을 이용하여 검증하는데 그 목적이 있다. 다짐횟수 검증을 위하여 굵은골재최대치수 13mm와 19mm 1등급 골재와 가열아스팔트 혼합물용 PG64-22와 PG76-22, 중온아스팔트 혼합물용 PG70-22 아스팔트를 사용하였다. 또한, 각각의 바인더 별로 권장 다짐온도를 기준으로 4가지 온도에서 선회다짐 100회와 마샬다짐 75회의 다짐량을 비교하였다. 두 다짐기를 공극률 상으로 평가할 때 전반적으로는 선회다짐기의 다짐이 다소 더 잘 되었다. 공극률에 대한 분산분석 결과 두 다짐기 사이에 19mm 혼합물에서는 통계적 유의차가 나타났고 13mm의 경우 유의차가 나타나지 않았다. 특히 일정 다짐온도 이하에서 다졌을 경우 두 다짐기 모두 다짐이 불량하여 다짐온도를 확보하여 다짐하는 것이 매우 중요한 것으로 나타났다. 따라서, "가열 아스팔트 혼합물의 생산 및 시공"에서 제시한 선회 다짐횟수 100회는 지침에서 제시한 아스팔트 혼합물의 다짐온도를 준수한다면 마샬다짐기 양면 75회 다짐과 유사하거나 다소 좋은 다짐 량을 나타내는 것을 알 수 있었다. The objective of this study is to validate the number of gyrations of Superpave gyratory compactor(SGC) for compaction of hot-mix asphalt (HMA) and warm-mix asphalt(WMA) mixtures. Marshall compaction was also used for comparison purpose. The 13mm and 19mm aggregates of 1st class quality shape were used. A PG64-22 and a PG76-22 for HMA and a PG70-22 for WMA. Four compaction temperatures based on the suggested value were used for each binder using 100 gyrations for SGC and 75 blows per side for Marshall compactor. It was found that SGC compaction was somewhat better than Marshall compaction. The analysis of variance showed that two compactors were significantly different in air voids of 19mm mixtures at <TEX>${\alpha}=0.05$</TEX> level. The 13mm mixture did not show a significant statistical difference. When compacted at the temperature below a certain level, however, the compaction of two compactors were fond to be proor. Therefore, observing compaction temperature above the minimum level is important to secure proper compaction work. If the minimum temperatures were maintained, 100 gyrations, which was given for HMA of arterial road pavement by the Korean Guide, was found to be appropriate compaction, showing similar or better compaction work than 75 blows per side of Marshall compaction.

Effects of Moist Aggregates on the Performance of Warm Mix Asphalt Mixtures Containing Non-Foaming Additives

Abstract The objective was to conduct a laboratory investigation of moisture susceptibility and rutting resistance of non-foaming warm mix asphalt (WMA) mixtures containing moist aggregates. Gyration number and weight loss of various samples, indirect tensile strength (ITS), tensile strength ratio (TSR), rut depths of dry and moisture conditioned specimens, as well as failed temperatures and rutting factors of recovered binders were measured for all mixtures. The experimental design included two aggregate moisture contents (0 and ∼0.5 % by weight of the dry mass of the aggregate), two lime contents (1 and 2 % lime by weight of dry aggregate) and one liquid anti-stripping agent (ASA), three non-foaming WMA additives (Cecabase®, Evotherm®, and Rediset®) with control, and two aggregate sources. A total of 34 mixtures were designed and a total of 340 specimens were tested in this study. The test results indicated that the aggregate source significantly affects the ITS and rutting resistance regardless of the WMA additive, ASA, and moisture content. In addition, the ITS and rut depth of the non-foaming WMA mixtures containing moist aggregates generally satisfied the demand of pavement without additional treatment. The mixtures with three WMA additives exhibited similar rutting resistance under dry and wet conditions. The liquid ASA, used in this study, for moisture resistance is not recommended to use in WMA mixtures containing moist aggregates as the aggregate is sensitive to moisture.