PROPERTIES OF AGGREGATES


 

 

 

 

 

 

 

 

 

1.  AGGREGATES: BULK DENSITY, SPECIFIC GRAVITY AND VOIDS

BULK DENSITY

River sand

Fine

1.44

Medium

1.52

Coarse

1.60

 

Beach or river shingle

1.60

Broken stone

1.60

Stone screenings

1.44

Broken Granite

1.68

 

SPECIFIC GRAVITY

Trap

2.9

Granite

2.8

Gravel

2.66

Sand

2.65

 

VOIDS, PERCENT, AVERAGE

River sand

Fine

43

Coarse

35

 

Mixed and moist

38

Mixed and dry

30

 

Broken stone, graded

25 mm maximum size

46

50 mm maximum size

45

63 mm maximum size

41

 

Stone screenings

48

 

Note: Above values are indicative only

 

 

 

 

2. AGGREGATES: LIMITING VALUES OF MECHANICAL PROPERTIES

PROPERTIES

LIMITING VALUES (PERCENTAGE)

FOR WEARING SURFACES

OTHERTHAN FOR WEARING SURFACES

Crushing value

30

45

Impact value

30

45

Abrasion value (Los Angeles)

30

50

Soundness (Average loss of weight after 5 cycles)

When tested with Na2SO4

When tested with MgSO4

Fine aggregates

10

15

Coarse aggregates

12

18

*Source- IS: 383 – 1970 

 

3. APPROXIMATE WATER ABSORPTION OF AGGREGATES, BY WEIGHT

Average sand

1.0 percent

Pebbles and crushed limestone

1.0 percent

Trap rock and granite

0.5 percent

Porous sandstone

0.5 percent

Very light and porous aggregates may absorb as much as

25 percent by weight

 

Note: The coarser the aggregate, the less free water it carries.

 

4. LIMITS OF DELETERIOUS MATERIALS (Percentage by weight, maximum)

(Clause 3.2.1 of IS: 383 – 1970)

DELETERIOUS SUBSTANCES

FINE AGGREGATES

COARSE AGGREGATES

Uncrushed

Crushed

Uncrushed

Crushed

Coal and lignite

1.00

1.00

1.00

1.00

Clay lumps

1.00

1.00

1.00

1.00

Materials finer than 75 micron sieve

2.00

15.00

3.00

3.00

Shale

1.00

-

-

-

Total of percentages of all deleterious materials **

5.00

2.00

5.00

5.00

**Mica is excluded.

 

5. BULKING OF SANDS FOR VARIOUS MOISTURE CONTENTS

Moisture, percent

Percentage bulking in

Fine sand

Medium sand

Coarse sand

1

16

8

6

2

26

16

12

3

32

22

15

4

36

27

17

5

38

29

18

6

37

28

18

8

35

26

16

10

32

22

12

12

28

19

8

15

22

12

2

17

18

7

0

20

9

0

0

27

0

0

0

 

 

6. SURFACE WATER CARRIED BY AGGREGATES

AGGREGATES

APPROXIMATE QTY OF SURFACE WATER

Percent by mass

Ltr./cu.m

Very wet sand

7.5

120

Moderately wet sand

5.0

80

Moist sand

2.5

40

Moist gravel or crushed rock

1.25 – 2.5

20 – 40

 

Note: Coarser the aggregate, less the water it will carry

Source: Table 10 of IS: 456 – 2000


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