1 aggregate

Aggregates for Concrete

ByProf. Adel El Kordi

&Dr. Meheddene Machaka

Structural Engineering DepartmentFaculty of EngineeringBeirut Arab University

CVLE 321

1

Fine Aggregate Sand and/or

crushed stone

< 5 mm (0.2 in.)

F.A. content usually35% to 45% bymass or volume oftotal aggregate

2

Coarse Aggregate

Gravel andcrushed stone

5 mm (0.2 in.) typically between

9.5 and 37.5 mm(3/8 and 1½ in.)

3

Rock and MineralConstituents in Aggregates

1. Minerals2. Igneous rocks3. Metamorphic rocks4. Sedimentary rocks

4


Silica Quartz, Opal

Silicates Feldspar, Clay

Carbonate Calcite, Dolomite

1. Minerals

5


SulfateGypsum, Anhydrite

Iron sulfide Pyrite, Marcasite

Iron oxide Magnetite, Hematite

1. Minerals

6


Granite Syenite Diorite Gabbro Peridotite

Pegmatite Volcanic

glass Felsite Basalt

2. Igneous rocks

7


Conglomerate Sandstone Claystone, siltstone,

argillite, and shale Carbonates Chert

3. Sedimentary rocks

8


Marble Metaquartzite Slate Phyllite Schist

4. Metamorphic rocks

Amphibolite Hornfels Gneiss Serpentinite

9

Normal-Weight Aggregate

Most common aggregates Sand Gravel Crushed stone

ASTM C 33

Produce normal-weight concrete2200 to 2400 kg/m3 (140 to 150 lb/ft3)

10

Lightweight Aggregate (1)

Expanded ShaleClay Slate Slag

ASTM C 330

Produce structural lightweight concrete1350 to 1850 kg/m3 (90 to 120 lb/ft3)

11

Lightweight Aggregate (2) Pumice Scoria Perlite Vermiculite Diatomite

Produce lightweight insulatingconcrete— 250 to 1450 kg/m3

(15 to 90 lb/ft3)12

Heavyweight Aggregate

Barite Limonite Magnetite Ilmenite Hematite Iron Steel punchings or shot

ASTM C 637, C 638 (Radiation Shielding)

Produce high-density concrete upto 6400 kg/m3 (400 lb/ft3) 13

Particle shape

Classify coarse aggregates according to their particle shape

14

Aggregate Characteristics and Tests (1)Characteristic TestAbrasion resistance ASTM C 131 (AASHTO T 96), ASTM C 535, ASTM C 779Freeze-thawresistance

ASTM C 666 (AASHTO T 161), ASTM C 682,AASHTO T 103

Sulfate resistance ASTM C 88 (AASHTO T 104)Particle shape andsurface texture ASTM C 295, ASTM D 3398

Grading ASTM C 117 (AASHTO T 11), ASTM C 136 (AASHTO T27)

Fine aggregatedegradation ASTM C 1137

Void content ASTM C 1252 (AASHTO T 304)Bulk density ASTM C 29 (AASHTO T 19)

15

Aggregate Characteristics and Tests (2)Characteristic TestRelative density ASTM C 127 (AASHTO T 85)—fine aggregate

ASTM C 128 (AASHTO T 84)—coarse aggregateAbsorption andsurface moisture

ASTM C 70, ASTM C 127 (AASHTO T 85), ASTM C 128(AASHTO T 84), ASTM C 566 (AASHTO T 255)

Strength ASTM C 39 (AASHTO T 22), ASTM C 78 (AASHTO T 97)Def. of constituents ASTM C 125, ASTM C 294

Aggregateconstituents

ASTM C 40 (AASHTO T 21), ASTM C 87 (AASHTO T 71),ASTM C 117 (AASHTO T 11), ASTM C 123 (AASHTO T113), ASTM C 142 (AASHTO T 112), ASTM C 295

Alkali Resistance ASTM C 227, ASTM C 289, ASTM C 295, ASTM C 342, ASTM C586, ASTM C 1260 (AASHTO T 303), ASTM C 1293

16

Grading of Aggregate―Grading is the particle-size distribution

of an aggregate as determined by asieve analysis using wire mesh sieveswith square openings.

ASTM C 33

Fine aggregate―7 standard sieves withopenings from 150 μm to 9.5 mm

(No. 100 to 3/8in.)

Coarse aggregate―13 sieves withopenings from 1.18 mm to 100 mm

(0.046 in. to 4 in.) 17

Range of Particle Sizes

18

Specific Gravity Flask for Fine Aggregate

Sieve Shakers for Testing Sieves

SievesLos Angeles Abrasion Machine

Specific Gravity Bench Set

Sample Splitter

Discuss briefly what you see in the following photographs:

19

Fine-Aggregate Grading LimitsSieve size Percent passing by mass

9.5 mm (3/8 in.) 1004.75 mm (No. 4) 95 to 1002.36 mm (No. 8) 80 to 1001.18 mm (No. 16) 50 to 85

600 µm (No. 30) 25 to 60300 µm (No. 50) 5 to 30 (AASHTO 10 to 30)150 µm (No. 100) 0 to 10 (AASHTO 2 to 10)

20

Maximum Size vs. NominalMaximum Size of Aggregate

Maximum size ― is the smallestsieve that all of a particularaggregate must pass through.

Nominal maximum size ― is thestandard sieve openingimmediately smaller than thesmallest through which all of theaggregate must pass.

The nominal maximum-size sievemay retain 5% to 15%

21

Nominal Maximum Size ofAggregate

1/5 then narrowest dimensionbetween sides of forms

3/4 clear spacing betweenrebars and between rebars andthe form

1/3 depth of slabs

Size should not exceed ―

22

Coarse Aggregate Grading

Sieve size Percent passingby mass

37.5 mm (1½ in.) 10025.0 mm (1 in.) 95 to 10012.5 mm (½ in.) 25 to 604.75 mm (No. 4) 0 to 102.36 mm (No. 8) 0 to 5

Size No. 5725 to 4.75 mm [1 in. to No. 4]

23

Grading Limits

24

Grading of coarse aggregate

% Passing% RetainedCumulativegm.

Retainedgm.

Sieve Size

8855.5141-

1244.58699-

120044508600990010000

1200325041501300100

3/2¾3/8

3/16Pan

25

Grading of Fine aggregate


Retainedgm.

Sieve Size

90755037198-

102550638192-

321

100250500630810920

1000

10015025013018011080

3/168163050

100PanTotal

Fineness Modulus (FM) = 321/100=3.2126

ExampleIt is required to deliver 5000 m3 of the all-in aggregate. The sieve

analysis of the used sand, gravel, and specification limits of the all-inaggregate are given in the following table. The unit weights of gravel,sand, and all-in aggregate are 1.70, 1.75 and 1.78 t/m3. The costs of 1.0 m3

of gravel and sand are 20 and 10 $, respectively. Calculate:1- The mixing ratio of sand to gravel to obtain the desired all-in agg.2- The amount and costs of sand and gravel.

10052251473/16"3/8"3/4"1"Sieve size----1000600094003200400Gravel (gm)53070809296100100100% Passing of sand

0-5-3-30--20-5040-7075-9595-100All-in aggregate,

Specifications' Limits(% passing)

27

% passing - Sand % passing - Gravel

% Sand/mix

100% 100%

0.0% 0.0%

0.0%100% 50% 30%

28


Retainedgm.

Sieve Size

98823550

2186595100

400360013000190002000056000

4003200940060001000

1¾3/8

3/16N0.8

chart method (Ratio of sand/gravel = 30% : 70%Sand = 0.30 x 5000 =1500m3 x 10 = 15000$Gravel = 0.70 x 5000 = 3500m3 x 20$ = 70000$Total coast = 85000$

10052251473/16"3/8"3/4"1"Sieve size000005358298%passing of gravel53070809296100100100% Passing of sand

0-5-3-30--20-5040-7075-9595-100All-in aggregate,

Specifications' Limits(% passing)

29

Reduction of Voids

•Explain why using sand only or gravel only as a concrete aggregate• may result in a low strength concrete? Draw and discuss:

30

Dispersion of Aggregates

31

Fineness Modulus (FM) Obtained by adding the sum of the

cumulative percentages by mass of asample aggregate retained on eachof a specified series of sieves anddividing the sum by 100.

The specified sieves are: 150 µm(No. 100), 300 µm (No. 50), 600 µm(No. 30), 1.18 mm (No. 16), 2.36 mm(No. 8), 4.75 mm (No. 4), 9.5 mm(3/8 in.), 19.0 mm (3/4 in.), 37.5 mm(1½ in.), 75 mm (3 in.), and 150 mm(6 in.).

32

Sieve Analysis and FM of Sand

Sieve size

Percentage ofindividual fractionretained, by mass

Percentagepassing,by mass

Cumulativepercentage re-tained, by mass

9.5 mm (3/8 in.) 0 100 04.75 mm (No. 4) 2 98 22.36 mm (No. 8) 13 85 151.18 mm (No. 16) 20 65 35600 µm (No. 30) 20 45 55300 µm (No. 50) 24 21 79150 µm (No. 100) 18 3 97

Pan 3 0 —Total 100 283

Fineness modulus = 283 ÷ 100 = 2.8333

Maximum Aggregate Size and Water Requirement

Draw and discus the relationship between the Maximum nominal Size of aggregate(on the horizontal axis) and water content (on the vertical axis).

34

Maximum Aggregate Size and Cement Requirement

Draw and discus the relationship between the Maximum nominal Size ofaggregate (on the horizontal axis) and Cement content (on the vertical axis).

35

Combined Aggregate Grading

36

Videograder

37

Moisture Conditions

Classify coarse aggregate according to their moisture conditions

38

Bulking of Sand

Explain the term Bulking of sand

39

40

D-Cracking

41

Drying Shrinkage

42

Harmful Materials (1)Substances Effect on concrete Test designation

Organicimpurities

Affects setting andhardening, maycause deterioration

ASTM C 40ASTM C 87

(AASHTO T 21)(AASHTO T 71)

Materials finerthan the 75-µm(No. 200) sieve

Affects bond,increases waterrequirement

ASTM C 117 (AASHTO T 11)

Coal, lignite, orother lightweightmaterials

Affects durability,may cause stainsand popouts


Soft particles Affects durability ASTM C 235

43

Harmful Materials (2)Substances Effect on concrete Test designation

Clay lumps andfriableparticles

Affects workabilityand durability, maycause popouts


Chert of lessthan 2.40relative density

Affects durability,may cause popouts

ASTM C 123ASTM C 295

(AASHTO T 113)

Alkali-reactiveaggregates

Causes abnormalexpansion, mapcracking, andpopouts

ASTM C 227,C 289, C 295,C 342, C 586C 1260, C 1293 (AASHTO T 303)

44

Popouts

45

Iron Particles in Aggregates

46

Alkali- AggregateReactivity ( AAR )

— is a reaction between the activemineral constituents of someaggregates and the sodium andpotassium alkali hydroxides andcalcium hydroxide in the concrete.

Alkali-Silica Reaction (ASR) Alkali-Carbonate Reaction (ACR )

47

Alkali-Silica Reaction (ASR) Visual Symptoms

Network of cracks Closed or spalled joints Relative displacements

48

Visual Symptoms (cont.) Fragments breaking out of

the surface (popouts)

Mechanism1. Alkali hydroxide + reactive

silica gel reactionproduct (alkali-silica gel)

2. Gel reaction product +moisture expansion

Alkali-Silica Reaction (ASR)

49

Influencing Factors Reactive forms of silica

in the aggregate, High-alkali (pH) pore

solution Sufficient moisture

If one of these conditions isabsent ― ASR cannot occur.


50

Test Methods Mortar-Bar Method

(ASTM 227) Chemical Method

(ASTM C 289) Petrographic Examination

(ASTM C 295) Rapid Mortar-Bar Test

(ASTM C 1260 or AASHTO T 303) Concrete Prism Test

(ASTM C 1293 )


51

Controlling ASR Non-reactive aggregates Supplementary cementing materials

or blended cements Limit alkali loading Lithium-based admixtures Limestone sweetening (~30%

replacement of reactive aggregatewith crushed limestone


52

Effect of SupplementaryCementing Materials on ASR

53

Alkali-Carbonate Reaction (ACR) Influencing factors

Clay content, or insoluble residuecontent, in the range of 5% to 25%

Calcite-to-dolomite ratio ofapproximately 1:1

Increase in the dolomite volume Small size of the discrete dolomite

crystals (rhombs) suspended in aclay matrix

54

Alkali-Carbonate Reaction

Test methods Petrographic examination

(ASTM C 295)Rock cylinder method (ASTM

C 586)Concrete prism test (ASTM C

1105)

55

Alkali-Carbonate Reaction

Controlling ACR Selective quarrying to avoid

reactive aggregate Blend aggregate according to

Appendix in ASTM C 1105 Limit aggregate size to smallest

practical

56

Handling and StoringAggregates

57

Recycled-ConcreteAggregate

58

59

Water Absorption

60

Videos 1/6

Aggregates Grading curves

61

Videos 2/6

Void content Fineness modulus

62

Videos 3/6

Gap graded aggregate Particle shape

63

Videos 4/6

Bulk Density (Unit Weight) Specific Gravity

64

Videos 5/6

Absorption Beneficiation

65

Videos 6/6

Handling and Storing

66