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

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Both standard test methods, including aggregate soaking time, cannot becompleted in a working day. It makes the tests less effective for quality controlpurposes, where results are desired as quickly as possible.3.2.4. Modifications for Determining SSD Condition of Fine AggregateMost modifications to the standard test methods have been undertaken in order to betterpinpoint the saturated surface-dry condition of fine aggregate and thereby improve theaccuracy of G sb test results. The G sb value is used to calculate the amount of asphaltbinder absorbed by the aggregate and the VMA of the HMA mixture. Thesemodifications along with their advantages and disadvantages are briefly described inTable 6.TABLE 6 Modifications of Standard Test Methods for Determining SSDCondition of Fine AggregateMethod Description Advantages DisadvantagesProvisional Fill cone mold and use 10 drops Easy and quick SameCone Test of tamperto perform shortcomings as(AASHTO T Add more FA and use 10, 3 andstandard test84 Note 2 2 drops of tamper, respectivelymethodand ASTM Level off and lift moldC128)verticallyKandhal andLeeColorimetric FA is soaked in watercontaining special dye thatchanges color when dry Easy to perform Dyes do not showwell on dark FAparticlesProcedure(AASHTO T Upon removal from water, FAhas color of wet dye Differentialdrying on particle84 Note 2 & SSD condition reached whensizeASTM material changes color TechnicianC128)judgment on colorPaper Towel(AASHTOT 84 Note 2and ASTMC128)California(CaliforniaTest 225:Option 1)Use hard-finished paper towelsto surface dry FASSD condition just achievedwhen paper towel not pickingup moisture from surface of FAPlace portion of drying FA in adry glass jar and shakeSSD condition is when FAceases to adhere to dry surfacechange required Easy to perform Technicianjudgment requiredEasy and quickto performTechnicianjudgment required8
TABLE 6 Modifications of Standard Test Methods for Determining SSDCondition of Fine Aggregate (cont.)Method Description Advantages DisadvantagesTexas(Tex 201-F)SSD condition is when 2 of 4criteria below satisfied: Criterion 1: drying FA slides insame manner as oven-dry FA Easy and quickto perform Technicianjudgment requiredslides down bottom of 45-degtilted pan Criterion 2: drying FA flowsfreely off a small masonry Easy and quickto perform Technicianjudgment requiredtrowel in same manner as ovendryFA when trowel tiltedslowly to one side Criterion 3: place water-solubleglue surface of wood block on Easy and quickto performdrying FA for 5 seconds. SSDcondition is when no more than2 particles adhere to watersoluble glue after 2 checks Criterion 4: drying FA hassame color as oven-dried FA Easy and quickto perform Technicianjudgment requiredWisconsin(Modified Minus No. 200 is removed byrinsing FA over No. 200 screen More consistentresults Technicianjudgment requiredAASHTOT 84) Does not includeminus No. 200Iowa(IM 380)FA is covered with water andplaced under 30 mm Hgvacuum for 30 min. and thenallowed to stand for another 20min. Sample is then rinsed overNo. 200 sieve. SSD conditionachieved when FA grains donot adhere to steel spatulaUsed for bothcombined andindividualaggregateNo soak timerequiredMore consistentresultsfractionTechnicianjudgment requiredDoes not includeminus No. 200fraction3.2.5. Alternatives to Standard Test MethodsSeveral alternatives to the AASHTO T 84 and ASTM C128 procedures are available todetermine fine aggregate G sb . These alternatives, along with their advantages anddisadvantages when compared to the standard test methods, are briefly described in Table7.9
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: TABLE 4 AASHTO T 84 and ASTM C128 P
Page 19 and 20: In 2000, Kandhal et al. (7) conduct
Page 21 and 22: angular fine aggregate with higher
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

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