Evaluation of Evaluation of Conventional, InfraConventional, Infra--red, red, and Vacuum Sealing and Vacuum Sealing methods for Specific methods for Specific Gravity measurementsGravity measurements

Presentation outlinePresentation outlineBackground.Background.Current methods for testing Specific Current methods for testing Specific Gravity.Gravity.Problem Statement.Problem Statement.Objective.Objective.Scope.Scope.Newly proposed methods.Newly proposed methods.Results.Results.Summary and Conclusion.Summary and Conclusion.Questions.Questions.

SignificanceSignificance

Mass/volume relation is key Mass/volume relation is key 0.01 change in gravity = .6 lb/cubic ft 0.01 change in gravity = .6 lb/cubic ft change in densitychange in density0.6 lb / cubic ft change = 0.5% 0.6 lb / cubic ft change = 0.5%

change in voidschange in voidsFine aggregates normally account for Fine aggregates normally account for 35 to 50% of the mix.35 to 50% of the mix.

Specific GravitySpecific Gravity

Provides a relation ship between mass and Provides a relation ship between mass and volume .volume .It is the ratio of the weight of the aggregate It is the ratio of the weight of the aggregate to the volume of the aggregate.to the volume of the aggregate.

Specific Gravity is an indicator of how heavy Specific Gravity is an indicator of how heavy a material is. a material is.

w VolumeMass G

γ=

Specific GravitySpecific Gravity(Aggregates)(Aggregates)

Dimensional measurements is Dimensional measurements is difficult, since aggregates have difficult, since aggregates have irregular shapes.irregular shapes.

VVbulkbulk = (= (WWssdssd –– WWsubmergedsubmerged) ) γγwaterwater

VVAppApp = (W= (WODOD –– WWsubmergedsubmerged) ) γγwaterwater

Volume is determined by the volume Volume is determined by the volume of water it displaces .of water it displaces .

Specific GravitySpecific Gravity(Mixture Maximum Specific (Mixture Maximum Specific Gravity)Gravity)Maximum Theoretical Specific Gravity Maximum Theoretical Specific Gravity

((GmmGmm): ): mass per volume of material mass per volume of material containing no air voids, compared to containing no air voids, compared to unit volume of waterunit volume of water

w VolumeMass G

γ=mm

Current methods for Current methods for measuring Gravitymeasuring GravityAggregatesAggregates

Fine aggregate Fine aggregate -- AASHTO T 84AASHTO T 84

Saturated Surface DrySaturated Surface Dry(SSD)(SSD)

Aggregate is well soaked.Aggregate is well soaked.Capillary pores saturated with water.Capillary pores saturated with water.Surface is dry.Surface is dry.

Conventional method Conventional method Fine AggregatesFine Aggregates

Problems with Problems with Conventional MethodConventional Method

Achieving proper SSD Condition.Achieving proper SSD Condition.Long testing time.Long testing time.

ObjectiveObjective

The objective of this study is:The objective of this study is:Evaluate alternative test methods to Evaluate alternative test methods to

determine the Specific Gravities of fine determine the Specific Gravities of fine aggregatesaggregates

ScopeScope

Materials Materials Fine aggregate:Fine aggregate:

1.1. #11 #11 LimeStoneLimeStone..2.2. #11 #11 SandStoneSandStone..3.3. Coarse Sand.Coarse Sand.

Alternative methods for testing Alternative methods for testing specific gravity of aggregatespecific gravity of aggregate

••Vacuum Sealing.Vacuum Sealing.••InfraInfra--redred

Vacuum SealingVacuum Sealing

InfraInfra--redred

RESULTSRESULTS

Comparison of Specific Gravity of fine Comparison of Specific Gravity of fine Aggregates:Aggregates: #11 LS#11 LS

#11 LS

2.580

2.633 2.632

2.450

2.550

2.650

2.750

Gsb

(dry

)

ConventionalSSDetectCorelok

BA A

#11 LS

2.714 2.690 2.690

2.450

2.550

2.650

2.750

Gsa

(dry

)

ConventionalSSDetectCorelok

A A A

#11 LS

1.913

0.800 0.835

0.000

0.500

1.000

1.500

2.000

2.500

% W

ater

Abs

orpt

ion

ConventionalSSDetectCorelok

A B B

Comparison of Specific Gravity of Comparison of Specific Gravity of fine Aggregates:fine Aggregates: #11 SS#11 SS

#11 SS

2.5372.565

2.534

2.350

2.450

2.550

2.650

Gsb

(dry

)ConventionalSSDetectCorelok

A AA

#11 SS

2.6792.653

2.663

2.450

2.550

2.650

2.750

Gsa

(dry

)

ConventionalSSDetectCorelok

A AA

#11 SS

2.093 1.267 1.918

0.000

1.000

2.000

3.000

4.000

% W

ater

Abs

orpt

ion

ConventionalSSDetectCorelok

A BA

Comparison of Specific Gravity of Comparison of Specific Gravity of fine Aggregates:fine Aggregates: Coarse SandCoarse Sand

C.Sand

2.614 2.6102.613

2.450

2.550

2.650

2.750

Gsb

(dry

)

ConventionalSSDetectCorelok

AA A

C.Sand

2.6452.646 2.653

2.450

2.550

2.650

2.750

Gsa

(dry

)

ConventionalSSDetectCorelok

A A A

C.Sand

0.60.4 0.5

0.0

0.2

0.4

0.6

0.8

1.0

% W

ater

Abs

orpt

ion

ConventionalSSDetectCorelok

A/BB A