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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Evaluation of WisDOT Quality Management Program (QMP) Activities and Impacts on Pavement Performance</title>
      <link>https://trid.trb.org/View/1637718</link>
      <description><![CDATA[This project aims to evaluate the effectiveness of the quality measures employed by the Wisconsin Department of Transportation to influence the in-service performance of flexible pavements. The study involved creating a relational geo-referenced database connecting production, placement, and routine in-service performance data collected over the years for Wisconsin Projects. The database relied on geo-referencing all the data such that each individual data point is assigned a location. This approach allows for tracking the quality of the material and construction of specific segments of the roadway to the in-service performance. A subset of the projects was also included in an in-depth study using on-site distress survey and non-destructive testing using Falling Weight Deflectometer (FWD). In general, the thirty highway projects studied in this project show that transverse and longitudinal cracking are the most common distresses. Construction joint longitudinal cracking appears to be highly common in all the on-site visits. Rutting is localized but not common. Alligator cracking takes place in multiple locations. This distress appears to relate to either soft foundation or some of the quality measures. Deviations from the quality indicators’ targets show correlations with the distresses. Mix production air voids (Va), mix voids in mineral aggregate (VMA), and placement density (%Gmm) are correlated with in-service performance. Deviation from target Va by reduction of 0.25% or more, correlates with a reduction in performance. Accomplishing VMA higher than the target is associated with lower levels of distresses. For %Gmm, about 2% increase in the compacted density shows improved performance for thicker than 2” lifts. Thin lifts are more sensitive to increase in compaction effort than thicker pavements.]]></description>
      <pubDate>Mon, 22 Jul 2019 15:30:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1637718</guid>
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    <item>
      <title>Conceptualizing the asphalt film thickness to investigate the Superpave VMA criteria</title>
      <link>https://trid.trb.org/View/1540664</link>
      <description><![CDATA[Asphalt binder film thickness (FTb) is the key factor that is responsible for durability of asphalt mixtures. Mixtures with coarse aggregate gradations have difficulty meeting the Superpave minimum voids in mineral aggregate (VMA) criteria even though they tend to have thick asphalt films. In this study, the concept of asphalt binder film thickness (FTb) was used to investigate the Superpave VMA criteria. Superpave aggregate gradations of three nominal maximum aggregate sizes (NMAS): 9.5, 12.5 and 19.0 mm, were used. Aggregate gradations passing above, below, crossover through, humped, and through restricted zone were all considered. Superpave Gyratory Compactor test data of 126 compacted asphalt mixtures were used in the study. The current Superpave VMA criteria relate the mixture durability with VMA and set the same VMA value for mixtures with the same NMAS regardless of other parameters. However, a poor relationship was found between VMA and FTb (a durability measure) with an R² ≅ 0.01, and yet a relatively good relationship (R² ≅ 0.38) was found between voids filled with asphalt (VFA) and FTb although the VFA volumetric phase is part of the VMA volumetric phase in the mixture. This result was justified by the poor relationship between VFA and VMA (R² ≅ 0.13). Despite that the effective binder content (P sub be ) as a volumetric phase represents the VFA in the mixture, the relationship between FTb and P sub be  was found to be more significant (higher R²) than the relationship between FTb and VFA. In this study, asphalt mixtures that did fail the Superpave VMA criteria in some cases had adequate asphalt FTb, and mixtures that passed the criteria did not necessarily have adequate FTb. In conclusion, although the current Superpave VMA criteria are significant, findings of this study support the tendency to modify the current criteria.]]></description>
      <pubDate>Mon, 01 Oct 2018 14:39:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1540664</guid>
    </item>
    <item>
      <title>Evaluation of Methods for Determining Bulk Specific Gravity of RAP Aggregate and Voids in Mineral Aggregate During Production of Asphalt Mixtures</title>
      <link>https://trid.trb.org/View/1496284</link>
      <description><![CDATA[During asphalt mixture production, the bulk specific gravity (Gsb) of mixture aggregate is not routinely measured to determine voids in the mineral aggregate (VMA) because it requires multiple tests and extended testing time. Instead, state agencies have used several alternatives to determine VMA of plant produced asphalt mixtures. The objective of this study is to determine the effect of these methods on the VMA determination during production. This study compared the results of four methods for determining Gsb of Reclaimed Asphalt Pavement (RAP) aggregate and six methods for calculating VMA of plant-produced mixtures. Materials, including virgin aggregate, RAP, and plant mix, were sampled during production from 10 projects in Florida. Properties of the sampled materials and mixtures, including Gsb of the virgin aggregate and RAP aggregate, the maximum specific gravity (Gmm) of RAP and plant mix, the bulk specific gravity (Gmb) of compacted mix, and asphalt content, were determined through laboratory testing. The Gsb of RAP aggregates and VMA of mixtures were determined using the methods evaluated, and their effects on Gsb and VMA were investigated. The study results indicated that Gsb of ignition-extracted RAP aggregate and the total aggregate blend can be used to calculate the VMA of the mix during mix design and production if it has been adjusted to account for the effect of the ignition method on the aggregate material.]]></description>
      <pubDate>Wed, 28 Feb 2018 13:25:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1496284</guid>
    </item>
    <item>
      <title>Effect of Superpave restricted zone on volumetric and compaction properties of asphalt mixtures</title>
      <link>https://trid.trb.org/View/1487673</link>
      <description><![CDATA[The Superpave aggregate criteria originally include a restricted zone that lies along the maximum density line and through which gradations are not recommended to pass. The debate with regard to whether or not such a restriction needs to be imposed has been ongoing and inconclusive. In this study, fifteen different gradations of limestone aggregate having three nominal maximum aggregate sizes (NMAS) of 19.0, 12.5, and 9.5 mm and covering five types: above, below, crossover through, hump through, and through restricted zone (ARZ, BRZ, CRZ, HRZ, and TRZ) were used to investigate the effect of restricted zone on mixture properties. The Superpave gyratory compactor (SGC) was used to produce the asphalt mixture samples according to the Superpave system. Findings of the study showed that the CRZ, HRZ, and TRZ mixtures generally could meet the Superpave voids in mineral aggregate (VMA) criteria easier than the BRZ and ARZ mixtures. Contrary to the expected trend, the VMA values for the BRZ mixtures were found to be higher than those of the ARZ mixtures for the 19.0-mm NMAS. The HRZ mixtures similar to the ARZ and BRZ mixtures had high effective asphalt binder content. ARZ mixtures generally could violate the Superpave criteria for compaction properties (% of maximum specific gravity at the initial number of gyrations, %G sub mm at N sub initial, and % of maximum specific gravity at the maximum number of gyrations, %G sub mm at N sub maximum). The TRZ mixtures in general provided the highest dust proportion (DP) values, whereas, the BRZ mixtures provided the lowest DP values.]]></description>
      <pubDate>Mon, 13 Nov 2017 16:31:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1487673</guid>
    </item>
    <item>
      <title>Study of Type 'A' Asphaltic Concrete Surface Mix Design</title>
      <link>https://trid.trb.org/View/1392071</link>
      <description><![CDATA[In some asphaltic concrete mixes asphalt absorption in field mixes is difficult to predict by the routine mix design tests presently being used. Latent or slow absorption in hot mixes is hard to compensate for in field control due to aggregate gradations being near maximum density. If critical asphalt need could be changed by increasing voids in the mineral aggregate (VMA) so that more freedom could be exercised in compensating for the absorption, this may aid in design. The VMA can be related to composite gradation of total aggregate in a mixture, i.e., if a composite gradation of aggregate is finer than that of maximum density curve, the VMA will be greater than that of a mix of maximum density. The typical gradation of Iowa Type 'A' mixes is finer than a gradation which is near the centerline of the specification at sieves larger than the No. 30 and coarser at the lower sieve sizes. The mixes of the typical gradation will have higher VMA than those of the near centerline mixes. By studying properties of the mixes of the typical gradation and comparing them with those of the mixes of maximum density, it may aid in the modification and simplification of the present testing methods and specification requirements while still maintaining control of quality of the mix by controlling voids, stability, gradation and asphalt content.]]></description>
      <pubDate>Sun, 10 Jan 2016 17:15:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1392071</guid>
    </item>
    <item>
      <title>Structural Analysis of Aggregate Blends Using the SHRP Gyratory Compactor</title>
      <link>https://trid.trb.org/View/1391753</link>
      <description><![CDATA[The Iowa Department of Transportation (IDOT) received a Strategic Highway Research Program (SHRP) gyratory compactor in December of 1994. Since then the IDOT has been studying the ability of the compactor to analyze fundamental properties of aggregates such as shape, texture, and gradation, by studying the volumetrics of the aggregate blends under a standard load using the SHRP gyratory compactor. This method of analyzing the volumetrics of aggregate blends is similar to SHRP's fine aggregate angularity procedure, which analyzes void levels in noncompacted aggregate blends, which in turn can be used to evaluate the texture and/or shape of aggregates, what SHRP refers to as angularity. Research is showing that by splitting the aggregate blend on the 2.36 mm (#8) sieve and analyzing the volumetrics or angularity of the separated blend, important fundamental properties can be determined. Most important is structure (the degree and location of aggregate interlock). In addition, analysis of the volumes of the coarse and fine portions can predict the voids in the mineral aggregate (VMA), and the desired asphalt content. By predicting these properties it can be determined whether or not the combined aggregate blend, when mixed with asphalt cement, will produce a mix with structural adequacy to carry the designed traffic load.]]></description>
      <pubDate>Sun, 10 Jan 2016 17:15:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1391753</guid>
    </item>
    <item>
      <title>Minimum VMA in HMA Based on Gradation and Volumetric Properties</title>
      <link>https://trid.trb.org/View/1391752</link>
      <description><![CDATA[The use of voids in the mineral aggregate (VMA) criteria for proper mix design of hot mix asphalt (HMA) mixtures is a time honored and fairly successful tool. Recent developments in the field of asphalt mix design have encouraged the use of mixtures with a coarse aggregate structure to resist the affect of heavy traffic loads. By using the equations presented, which account for both aggregate gradation and the volumetric properties of the materials, the mix designer is able to judge the proper VMA requirement for each unique blend of materials. By applying the new equations, the most economical mix may be selected without great risk of reduced durability. Supporting data from field application are presented to illustrate the use of the equations.]]></description>
      <pubDate>Sun, 10 Jan 2016 17:15:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1391752</guid>
    </item>
    <item>
      <title>Use of Mechanistic Models to Investigate Fatigue Performance of Asphalt Mixtures: Effects of Asphalt Mix Design Targets and Compaction</title>
      <link>https://trid.trb.org/View/1339172</link>
      <description><![CDATA[Effects of design air void contents, design voids in mineral aggregate (VMA), and in-place air voids on the fatigue performance of asphalt mixtures were investigated with mechanistic analyses based on the viscoelastic continuum damage (VECD) analyses and the mechanistic–empirical pavement analysis using the AASHTOWare Pavement ME Design program. The VECD analyses included the simplified viscoelastic continuum damage model at the material level and two structural models: (a) layered viscoelastic analysis and (b) layered viscoelastic pavement analysis for critical distresses. The mix design of a 2013 accelerated loading facility test lane was selected to develop the volumetric mix designs with the design air voids of 3%, 4%, and 5%, design VMAs of 13%, 14%, and 15%, and in-place air void contents of 5%, 7%, and 9% with the Bailey method. Dynamic modulus and direct tension cyclic fatigue tests were performed in accordance with the AASHTO TP 107 procedure. The test results showed that the linear viscoelastic property was affected by the design VMA, design air void content, and in-place air void content in order of sensitivity. Also, the damage states at failure determined from the damage characteristic curves and the mechanistic fatigue predictions had consistent trends as observed for the design VMA, in-place air void, and design air void content in rank of sensitivity. Finally, the design VMA, in-place air void, and design air void parameters were found to be sensitive in the mechanistic analyses, whereas the parameter that was most sensitive in the pavement mechanistic–empirical analysis was the in-place air void content.]]></description>
      <pubDate>Thu, 29 Jan 2015 15:07:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1339172</guid>
    </item>
    <item>
      <title>Superpave Mix Designs for Arkansas</title>
      <link>https://trid.trb.org/View/1335500</link>
      <description><![CDATA[Superpave, an asphalt concrete mixture design procedure developed under the Strategic Highway Research Program (SHRP), is to be implemented state-wide in Arkansas in 1998. The Arkansas State Highway and Transportation Department (AHTD) sponsored TRC-9604, Superpave Mix Designs for Arkansas, to investigate potential impacts of Superpave implementation on current mix design practice. Aggregates currently used in Arkansas for hot-mix asphalt concrete (HMAC) appear to be acceptable for use in Superpave. It is recommended that AHTD retain (and slightly refine) existing specifications for aggregate source properties, and adopt Superpave specifications for aggregate consensus properties. Recommended adoption of Superpave gradation specifications may result in significant reductions in the use of sand-sized aggregates in HMAC, particularly natural (rounded) sands. HMAC volumetric analysis in Superpave is similar to current AHTD methods, with two notable differences — the method for calculating voids in the mineral aggregate (VMA), and the definition of the dust proportion ("fines to asphalt ratio"). It is recommended that AHTD adopt Superpave specifications in both instances. It is also recommended that AHTD refine its method for estimating the moisture sensitivity of an HMAC mixture (where it currently uses the Marshall stability test) to reflect current Superpave methodology — the use of the split-tensile strength to determine the effect of moisture on the mix. Overall, the transition from traditional Marshall based mix design to Superpave is certainly feasible, and can be accomplished using current Arkansas aggregates.]]></description>
      <pubDate>Mon, 22 Dec 2014 19:11:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/1335500</guid>
    </item>
    <item>
      <title>Development of Quality Control Procedures for Hot-Mix Asphalt</title>
      <link>https://trid.trb.org/View/1335248</link>
      <description><![CDATA[The Arkansas quality control/quality assurance (QC/QA) specification for hot mix asphalt (HMA) construction was initially developed from data and experience gained with the Marshall method of mix design. The full implementation of Superpave resulted in questions relating to the suitability of the QC/QA specification. Research was undertaken to revise the existing program or create a new specification. Six projects were randomly sampled and tested by three operators (the contractor, the agency, and the research team) to establish typical HMA construction variability, in terms of the pay factors used in Arkansas: air voids, voids in the mineral aggregate (VMA), binder content, and field density. The testing data were normally distributed, validating a typical assumption regarding construction. Analyses showed testing variability among the three operators could be absorbed into the overall variability of test properties, rather than being considered a distinct factor. Three levels of HMA quality were identified by the mean and standard deviation of test data. A specification for QC/QA was proposed, which features acceptance criteria based on both the mean value of a given property (similar to the existing specification) and an acceptable range of the property. The acceptance criteria for both the mean and range are based on the standard deviation of the property expected in the field; for initial implementation, it is recommended that the ‘medium’ quality level as defined by the testing program be used. A limited validation study was performed to gauge the effect of implementation. The study suggested that implementation of the proposed system would not result in drastic cases of materials/pavement rejection. Further, the study indicated that field compaction would be the current acceptance property most affected by the proposed system. It is strongly recommended a full-scale field validation study be conducted; details of such a study are included.]]></description>
      <pubDate>Tue, 16 Dec 2014 11:58:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1335248</guid>
    </item>
    <item>
      <title>Effects of Various HMA Material Properties on Pavement Performance</title>
      <link>https://trid.trb.org/View/1334571</link>
      <description><![CDATA[During hot mix asphalt (HMA) mixture design, mineral aggregates and asphalt binder are combined according to specifications with the expectation that if all requirements are met, the mix will be resistant to premature failure in the field. The volumetric properties of a mix are known to affect performance, although the specific nature of these relationships is difficult to quantify. The ability to alter mixture properties, such as voids in mineral aggregate (VMA) and gradation, in order to produce a desired outcome is perhaps one of the most useful tools a mix designer can possess. In this study, four aggregate sources were selected including limestone, sandstone, gravel, and syenite. From each aggregate source, two gradations (coarse-graded and fine-graded) surface mixtures were designed at three levels of VMA (low, medium, and high). For each of the 24 mix designs, rutting and stripping performance was measured using the University of Arkansas' Evaluator of Rutting and Stripping in Asphalt (ERSA) and Pines AFW1A Rotary Asphalt Wheel Tester (RAWT). The results of these tests were used to quantify the effects of VMA and gradation type on rutting resistance. Also, qualitative trends were developed relating other volumetric and gradation properties to performance. The results of the study indicate that VMA affects rutting performance more significantly than gradation type. Each aggregate type exhibited a "natural" range of VMA, and mixtures designed with lower levels of VMA within this range were more resistant to rutting. Stripping characteristics were affected by both VMA and gradation, such that the coarse-graded mixtures of low VMA were the best performers. Overall, it is recommended that both fine- and coarse-graded mixtures be designed with lower VMA, with possible adjustments for the bulk specific gravity of the aggregate source. With respect to mix design, additional emphasis should be placed on ensuring that mixtures are designed "at the bottom of the VMA curve". Adjusting binder content to create an increase in VMA is likely to reduce performance. Instead, changes in VMA should be made by adjusting the structure of the aggregate blend. Regression analyses were used in an attempt to mathematically correlate volumetric properties with mixture performance. While definitive models remained elusive, several trends were noted. Film thickness was calculated according to the traditional surface area factors, and this method exhibited only a moderate trend with respect to rutting performance. It is believed that restrictions on this property, if accurately determined, could be used in addition to VMA to better manage the binder content of a mix design. Methods for the measurement of film thickness should be studied further.]]></description>
      <pubDate>Wed, 10 Dec 2014 14:17:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1334571</guid>
    </item>
    <item>
      <title>Performance of Replacing Traditional Natural Aggregates in Dense Grade Asphalt Concrete with Basic Oxygen Furnace Slag</title>
      <link>https://trid.trb.org/View/1316786</link>
      <description><![CDATA[This study focuses on how the voids in mineral aggregate (VMA) and performance of dense grade asphalt concrete (DGAC) are influenced by the 100% replacement of coarse natural aggregates with basic oxygen furnace (BOF) slag. By using different mixture designs to obtain the optimal asphalt content, and then conducting performance tests and analysis of variance (ANOVA) between the test set and the comparison set, this study explores whether the replacement of coarse natural aggregate with BOF slag would reduce the durability and strength of DGAC. The mixture design results show that the BOF aggregates decreased the VMA of hot-mix asphalt; however, laboratory performance tests, especially moisture sensitivity and creep tests, showed that the lack of VMA did not adversely affect the durability of DGAC. Based on these results, 100% replacement of coarse natural aggregates with BOF slag is considered feasible and worthy of further study.]]></description>
      <pubDate>Wed, 03 Sep 2014 10:32:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1316786</guid>
    </item>
    <item>
      <title>Evaluation of Superpave Mixtures with High RAP Content</title>
      <link>https://trid.trb.org/View/1272268</link>
      <description><![CDATA[The Kansas Department of Transportation (KDOT) is currently evaluating Superpave mixture performance with higher percentage of reclaimed asphalt pavement (RAP) materials. Hamburg Wheel Tracking Device (HWTD) tests were done on Superpave mixes with high RAP content sampled from a number projects across the state. Each mixture was subjected to 20,000 repetitions or 20-mm rut depth, whichever came first. The HWTD test results were also correlated with the volumetric parameters and other potentially significant factors. The analysis results showed that the rutting performance was significantly affected by the asphalt source and binder grade regardless of RAP content. The surface mixes with higher percentage of RAP material were not significantly susceptible to rutting compared to the mixes with moderate percentage of RAP material. Volumetric mix design parameters of these mixtures, except voids in mineral aggregate (VMA), were not significant in determining rutting performance. The rut depth decreased with increasing percent VMA for the mixes with moderate percentage (25%) of RAP materials.]]></description>
      <pubDate>Mon, 14 Jul 2014 16:50:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1272268</guid>
    </item>
    <item>
      <title>Volumetric and Mechanistic Characteristics of Asphalt Mixes Containing Recycled Asphalt Pavement</title>
      <link>https://trid.trb.org/View/1272480</link>
      <description><![CDATA[This study explored the potential of using up to 40% of recycled asphalt pavement (RAP) in Oklahoma mixes by determining the change in volumetric and mechanistic (namely, dynamic modulus and creep compliance) characteristics with the addition of RAP. One RAP source was used to study the change in volumetric and mechanistic characteristics on Superpave mix (Oklahoma S3) with a nominal maximum size (NMS) of 19 mm. A total of two mixes containing 25% RAP and the other containing 40% RAP, were designed and tested. It was found that the voids in mineral aggregate (VMA) and voids filled with aggregate (VFA) of the RAP mixes increased with increasing percentage of RAP. The creep compliance results showed an increase in the stiffness and a reduction in compliance of the mix due to increase in the RAP content. The dynamic modulus test results illustrated that the asphalt mix containing a higher amount of RAP has a higher dynamic modulus value.]]></description>
      <pubDate>Mon, 14 Jul 2014 16:50:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1272480</guid>
    </item>
    <item>
      <title>Measurement Method of Critical Voids in the Mineral Aggregate of AC-20</title>
      <link>https://trid.trb.org/View/1270544</link>
      <description><![CDATA[The voids in the mineral aggregate (VMA) is considered to be the most important mix design parameter which affects the durability of the asphalt concrete mix. This has traditionally been addressed during mix design by meeting a minimum VMA requirement, based solely upon the nominal maximum aggregate size without regard to other significant aggregate-related properties. The goal of this study is to determine the validity of the minimum VMA requirement versus nominal maximum aggregate size required in Marshall volumetric mix design. Specimens were compacted using the Superpave Gyratory Compactor (SGC), conventionally tested for bulk and maximum theoretical specific gravities and physically tested using the Triaxial creep test system under a repeated load confined configuration to identify the transition state from sound to unsound. AC-20 was classified in the light of fine, dense and coarse gradation. The AC-20C, AC-20D and AC-20F asphalt mixtures were tested as the object of study. The results clearly demonstrate that the volumetric conditions of a hot mix asphalt (HMA) mixture at the stable unstable threshold are influenced by a composite measure of the aggregate size gradation. The currently defined VMA criterion, while significant, is seen to be insufficient by itself to correctly differentiate sound from unsound mixtures. Under current specifications, many otherwise sound mixtures are subject to rejection solely on the basis of failing to meet the VMA requirement. Based on the laboratory data and analysis, a new paradigm to volumetric mix design is proposed that explicitly accounts for aggregate gradation factors.]]></description>
      <pubDate>Tue, 10 Jun 2014 11:49:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1270544</guid>
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