A Review of Aggregate and Asphalt Mixture Specific Gravity ...

More documents

Recommendations

Info

good as that of AASHTO T 84, whereas other studies have shown repeatability of theCoreLok method to be better.Like the AggPlus system, the SSDetect system does not require the material beimmersed in water for at least 15 hours or for the operator to determine SSD condition.The SSDetect system was compared to the AASHTO T 84 procedure in two projects, oneconducted by Prowell and Baker (9) and the other by Cross et al. (10). Materials used andresearch plans implemented in these studies were previously described. Prowell andBaker (9) reported that G sb results using the two methods were significantly different forthree aggregates, including washed diabase, rounded natural sand, and angular naturalsand. However, these differences were less than those between the CoreLok andAASHTO T 84 G sb results. The precision of the SSDetect method was better than that ofAASHTO T 84. Cross et al. (10) also found significant differences between G sb resultsdetermined by the SSDetect and AASHTO T 84 methods. In addition, the SSDetectmethod produced the highest G sb results, followed by the CoreLok and AASHTO T 84.However, the SSDetect system has better reproducibility than the other two methods. Insummary, the two studies showed the significant differences between G sb resultsdetermined by the SSDetect and AASHTO T 84 methods. In addition, the precision of theSSDetect system was better than that of AASHTO T 84. However, the studies haddifferent conclusions on the differences in G sb results using the CoreLok, SSDetect, andAASHTO T 84 methods. These different conclusions may be due to different materialsused in the two studies.For the method using the Langley de-airing device with AASHTO T 84, onestudy was conducted by Cross et al. (10). The study compared G sb results using theAASHTO T 84 procedure with hand agitation and with a Langley de-airing device for 20minutes to remove air bubbles from the sample in the flask. They reported that the use ofthe Langley de-airing device improved the reproducibility of the test results; however, theresults were not statistically different in most cases.The Phunque method has been approved for use in New Mexico since July 1,2006. However, no published evaluation study is available at the time of this writing. Apreliminary comparison shown in an electronic presentation received by the authorsshowed that G sb results using the Phunque method were higher than those using theAASHTO T 84 method.Equipment for the Gilson Water Rapid Displacement method is currently beingdeveloped and therefore no study results are available for the method.In summary, most recent studies of alternative test methods for determining fineaggregate G sb focus on evaluating two recently developed test procedures, including theAggPlus and SSDetect methods. These methods have been developed to avoid thedetermination of SSD condition manually and to reduce the aggregate soaking time. Thestudies show that G sb results determined using alternative test methods are statisticallydifferent from those using AASHTO T 84. The differences appear to be greater for more12
angular fine aggregate with higher dust contents. Among the alternative methodsevaluated, the SSDetect has better precision than AASHTO T 84.13
Page 1 and 2: NCAT Report 12-06A REVIEW OF AGGREG
Page 3 and 4: Objective and Process of the Review
Page 5 and 6: warranted in these methods at this
Page 7 and 8: Table of Contents1. Introduction ..
Page 9 and 10: 1 INTRODUCTIONCurrent practices for
Page 11 and 12: 3 BULK SPECIFIC GRAVITY OF AGGREGAT
Page 13 and 14: TABLE 3 Advantages and Disadvantage
Page 15 and 16: TABLE 4 AASHTO T 84 and ASTM C128 P
Page 17 and 18: TABLE 6 Modifications of Standard T
Page 19: In 2000, Kandhal et al. (7) conduct
Page 23 and 24: ASTM does not specify an absorption
Page 25 and 26: 4.3. Alternatives to Current Standa
Page 27 and 28: 5 BULK SPECIFIC GRAVITY OF COMPACTE
Page 29 and 30: TABLE 15 Advantages and Disadvantag
Page 31 and 32: inaccurate sample volumes caused by
Page 33 and 34: For G sb , the specific gravity val
Page 35 and 36: line). Since it may be more desirab
Page 37 and 38: Both standard test procedures, incl
Page 39 and 40: 8 RECOMMENDATIONSBased on the revie
Page 41 and 42: REFERENCES1. The Proficiency Sample

A Review of Aggregate and Asphalt Mixture Specific Gravity ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?