aggregates

Material for Civil Engineering

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Aggregate gradation

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UNIFORM G A P CONTINUOUS

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Gradation and Aggregate Building

• Aggregate gradation affects the workability of portland cement concrete mixes, and the stability and durability of bituminous concrete mixes, also affects the stability, drainage and frost resistance of base course

• Aggregate grading: dense; gap; uniform; open graded

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Gradation and Aggregate Building

• Fuller method: P = 100 d/D

p = percentage finer than sieveD = maximum size aggregate to be used (top size)d = sieve size in questionN = coefficient of adjustment which adjusts the curve for

fineness or coarseness

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Fuller curve

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100

90

80

70

60

50

40

30

20

10

0

Pe

rce

nt

fine

r b

y w

eig

ht

Diameter in mm – log scale

n = 0.3

n = 0.5

n = 0.7

10 1 0.1

Fine aggregates limits

SIEVE SIZE PASSINGmm inch %

9.50 3/8 100

4.75 No. 4 95 - 100

2.36 No. 8 80 - 100

1.18 No. 16 50 - 85

600 m No. 30 25 - 60

300 m No. 50 10 - 30

150 m No. 100 2 - 10

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Graphical distribution

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CONTINUOUS

UNIFORM

Increasing particle size (sieve opening)

Incr

easi

ng c

umul

ativ

e p

erc

enta

ge p

assi

ng

G A P

Sieve test result

Sieve Size (mm)

no Weight retained (gr)

% retained Cumulative retained (%)

Cumulative passing (%)

4.75 4 0 0 0 100

2.36 8 241.9 11.9 11.9 90.6

1.18 16 388.9 19.1 31.0 74.0

0.60 30 505.5 24.9 55.9 51.7

0.30 50 543.4 26.7 82.6 25.1

0.15 100 340.8 16.8 99.4 8.4

pan 11.3 0.6 100.0 0

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Sieve Test Result

0

20

40

60

80

100

120

no 4 no 8 no 16 no 30 no 50 no 100 pan

cumm retained

cumm passing

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TYPICAL GRADATION

Sieve

designation

Percent finer than

A B C

2 in 100 100 100

1 ½ in 100 95 90 – 100

¾ in 63 85 65 – 80

No. 4 25 50 30 – 45

No. 10 15 36 20 – 35

No. 200 3 7 0 - 5

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TYPICAL GRADATION

0

20

40

60

80

100

120

2 in 1 ½ in ¾ in No. 4 No. 10 No. 200

abcc1

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Binding aggregates (2 materials)

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Percent aggregate A

Percent aggregate B

Pe

rce

nt

pa

ssin

g a

gg

reg

ate

A

Pe

rce

nt

pa

ssin

g a

gg

reg

ate

B

0 20 40 60 80 100

0 20 40 60 80 100

020

4060

8010

0

020

4060

8010

0

1.5”

3/4”

No. 4

No. 10

No. 200

Aggregates Moisture Phase

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Oven Dry Air Dry Saturated surface dry W e t

Absorption Capacity

Effective Absorption

Surface moisture

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Absorption Capacity WSSD - WOD

WOD

X 100

Effective Absorption

Moisture Content

Surface Moisture

WAGG - WOD

WOD

X 100

WWET - WSSD

WSSD

X 100

WSSD - WAD

WSSD

X 100

SPECIFIC GRAVITY

Ratio between mass (weight in air) to the mass of an equal volume of water (for a specific temperature)

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WOD

WSSD - WSW

WSSD

WSSD - WSW

WOD

WOD - WSW

Bulk Specific Gravity, Gb =

Bulk Specific Gravity, Gbsd =Saturated surface dry

Apparent Specific Gravity, Ga =

Flexible Pavement

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Asphalt concrete

Base course

Sub Base course

Sub Grade

TYPICAL CROSS SECTION

Aggregate for Pavement Base

• GRADATION

• PARTICLE STRENGTH

• PARTICLE SHAPE

• SURFACE TEXTURE

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Gradation

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Fine CoarseMedium

GRADATION

• Gradation affects: stability, drainage, and frost susceptibility;

• The type of gradation: dense graded (maximum stability), open graded (maximum drainage or frost protection);

• The hardness of the aggregate (ie.; aggregate degradation)

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Aggregate without fines

Void filled with fines Void overfilling by fines

STRENGTH Grain to grain contact only

Grain contact increase

Resistance to deform increase

Contact reduced the strength of mixture

Aggregate float in fines

DENSITY Varies (relatively low)

Pervious

Density increase Density decrease Practically impervious

STABILITY High in confine structure

Low in unconfined structure

High for confine and unconfined structure

Low stability

COMPACTION Hard to compact Relatively easy to compact

No problem

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Particle Strength

• To resist the load without breakdown, minimize degradation

• Requires: strength and toughness

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Particle Shape

• Angular aggregate characteristics give aggregate interlock properties; increase the stability of open graded materials.

• Rounded aggregate: Herrin and Goetz: crushing rounded gravels add significantly only to the

stability of one size aggregate mixes, to open graded mixes a very little,

and to dense mixes not at all • Thin and elongated aggregate: Size segregation; low strength

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Particle Texture (surface)

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Aggregate for Bituminous Mixture

• Gradation and Size:

(High volume of traffic: dense graded aggr., with sufficient void to leave room for fine and asphalt)

• Strength and Toughness: To prevent aggregate breakdown under traffic and subsequent los of

stability)

• Particle shape (angular aggr. gives aggr., interlock properties increasing stability of open

graded materials)

• Porosity

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Gradation for typical sand asphaltSieve

designation

passing

Percentage of total by weight

Grading A Grading B Grading C

½” 100 100 100

No. 4 95 – 100 95 – 100 90 – 100

No. 10 80 – 100 80 – 100 50 – 100

No. 40 50 – 80 50 – 95 35 – 70

No. 80 10 – 30 5 – 30 5 – 30

No. 200 0 – 8 0 – 8 0 – 8

Bitumen 4.0 – 6.0 4.0 – 6.0 4.5 – 6.5

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• This is en of session

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Assignment

1. Jenis batuan yang paling cocok untuk perkerasan jalan adalah “igneous rock”. Mohon komentar dan penjelasan mengenai keterangan tersebut.

2. Bagaimana bentuk (shape) dari partikel mempengaruhi penggunaannya untuk: -beton semen; -beton aspal?

3. Apa yang dimaksud dengan gradasi batuan?

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Sieve Size 4 8 16 30 50 100

Weight Retained (gr)

26 130 240 252 210 138

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1. Analisis saringan dari 1.000 gram batuan halus (fine) menghasilkan data sebagai berikut pada tabel. Mohon saudara gambarkan grafik gradasinya dan hitung modulus kehalusan (fineness modulus) dan apa saran saudara terhadap gradasi tersebut

Assignment

1. Pelajari dan gambarkan grafik gradasinya dari beberapa standar teknis (technical specification) mengacu kepada ASTM standar untuk gradasi batuan yang digunakan untuk:

campuran beton aspal campuran beton semen

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