This document discusses aggregates which are a key ingredient in concrete. It defines aggregates as a combination of different sized stones with a maximum size of 75mm. Aggregates are used as an underlying material for foundations and pavements and as an ingredient in concrete. The document classifies aggregates based on size, source, and density. It discusses important physical properties of aggregates such as strength, hardness, toughness, durability, porosity, and water absorption. It emphasizes that aggregates must be hard, durable, clean and free of impurities that could affect concrete hardness or damage reinforcement. Overall gradation and proper sizing of aggregates is important for quality concrete.

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AGGREGATES-
FUNCTION IN
CONCRETE
A TOPIC FROM CHAPTER CONCRETE MAKING
MATERIAL
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3. DEFINITION
• A COMBINATION OF DIFFERENT SIZES AND SHAPES
NORMALLY OF STONES.
• MAXIMUM SIZE IS 75 MM.
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4. 4

5. • AS AN UNDERLYING MATERIAL FOR FOUNDATIONS AND
PAVEMENTS
• AS AN INGREDIENTS IN PORTLAND CEMENT CONCRETE
AND ASPHALT CONCRETE.
USES OF AGGREGATES
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6. USES OF AGGREGATES
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7. • AGGREGATES SHALL BE HARD, DURABLE AND CLEAN AND
FREE FROM ADHERENT COATINGS AND ORGANIC MATTER
AND SHALL NOT CONTAIN APPRECIABLE AMOUNT OF CLAY.
• AGGREGATES SHALL NOT CONTAIN HARMFUL IMPURITIES
SUCH AS IRON PYRITES, ALKALIS, SALTS, COAL, MICA, SHALE
OR OTHER MATERIALS WHICH WILL AFFECT HARDENING AND
ATTACK REINFORCEMENT.
SELECTION OF AGGREGATES
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8. CLASSIFICATION OF AGGREGATES
BASED ON SIZE:
1. FINE AGGREGATES -
THOSE AGGREGATES WHICH PASS THROUGH 4.75 MM SIEVE OR
AGGREGATES WITH SIZE LESS THAN 5 MM.
1. COARSE AGGREGATES –
THOSE AGGREGATES PASSING THROUGH 75 MM SIEVE AND
ENTIRELY RETAINED ON 4.75 MM SIEVE OR THOSE
AGGREGATES WITH SIZE GREATER THAN 5 MM.
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9. CLASSIFICATION OF AGGREGATES
BASED ON SOURCE OR METHOD OF MANUFACTURE:
1. NATURAL AGGREGATE/UNCRUSHED AGGREGATE-
THOSE FROM THE RIVER BEDS, RIVER SAND AND EX-MINES. NORMALLY
ROUNDED IN SHAPE AND HAVE SMOOTH SURFACE TEXTURE.
1. MANUFACTURED AGGREGATE / CRUSHED AGGREGATE –
THOSE OBTAINED BY MECHANICALLY CRUSHING ROCKS, BOULDERS, OR
COBBLES. NORMALLY ANGULAR IN SHAPE AND HAVE ROUGH SURFACE
TEXTURE
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10. CLASSIFICATION OF AGGREGATES
BASED ON BASED ON SPECIFIC GRAVITY OR DENSITY MEASURED IN BULK :
1. LIGHTWEIGHT AGGREGATE
2. NORMAL-WEIGHT AGGREGATE
3. HEAVYWEIGHT AGGREGATE
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11. 1. LIGHTWEIGHT AGGREGATE
• FINE AGGREGATE AGGREGATE WITH BULK DENSITY < 1120KG/M3
• COARSE AGGREGATE ATE IS ANY AGGREGATE WITH BULK
DENSITY < 880KG/M3
• 2 TYPES OF LIGHTWEIGHT AGGREGATE:
 NATURAL LIGHTWEIGHT AGGREGATES (EG: PALM OIL SHELL, RICE
HUSK, ETC)
 MANUFACTURED (ALSO CALLED SYNTHETIC) LIGHTWEIGHT
AGGREGATES.
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12. 2. NORMAL WEIGHT AGGREGATE
• EXAMPLES : CRUSHED STONE, GRAVEL & ORDINARY SAND
• THEY ARE COMMONLY USED IN MANUFACTURE OF NORMAL
WEIGHT CONCRETE, ASPHALT CONCRETE AND ROADWAY SUB-
BASE.
• BULK DENSITY OF NORMAL WEIGHT AGGREGATE IS AROUND
1520 TO 1680KG/M3
.
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13. 3. HEAVYWEIGHT AGGREGATE
• THOSE AGGREGATE WITH HIGH DENSITY AND IS USED
PRIMARILY IN THE MANUFACTURE OF HEAVYWEIGHT
CONCRETE, EMPLOYED FOR PROTECTION AGAINST NUCLEAR
RADIATION AND AS BOMB SHELTER.
• THE UNIT WEIGHT OF HEAVYWEIGHT CONCRETE VARIES FROM
2400KG/M3
WITH S.G. RANGE FROM 4.0 TO 4.6 ..
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14. PHYSICAL PROPERTIES OF AGGREGATES
1. STRENGTH
2. HARDNESS
3. TOUGHNESS
4. DURABILITY
5. POROSITY
6. WATER ABSORPTION
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15. 1. STRENGTH OF AGGREGATES
• IN PRACTICE, MAJORITY OF NORMAL AGGREGATES ARE
CONSIDERABLY STRONGER THAN CONCRETE
• A GOOD AVERAGE VALUE OF CRUSHING STRENGTH OF
AGGREGATES IS 200N/MM2.
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16. 2. HARDNESS OF AGGREGATES
• ABILITY OF THE AGGREGATE TO WITHSTAND LOAD OR
APPLIED PRESSURE.
• THIS HARDNESS IS DEPENDING ON THE TYPE OF PARENT ROCK
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17. 3. TOUGHNESS
• IS THE RESISTANCE OF AGGREGATE TO FAILURE BY IMPACT.
• THIS CAN BE DETERMINED BY AGGREGATE IMPACT TEST.
• THE AGGREGATE IMPACT VALUE SHALL NOT EXCEED 45% BY
WEIGHT FOR AGGREGATE USED FOR CONCRETE OTHER THAN
THOSE USED FOR WEARING SURFACES AND 30% FOR CONCRETE
FOR WEARING SURFACES.
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18. 4. DURABILITY OF AGGREGATES
• ABILITY OF THE AGGREGATE TO WITHSTAND EXTERNAL OR
INTERNAL DAMAGING ATTACK OR IN OTHER WORDS THE
SOUNDNESS OF AGGREGATE.
• THIS CAN BE OBTAINED BY CARRYING OUT THE SOUNDNESS
TEST.
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19. 5. POROSITY
• AGGREGATE NORMALLY HAVE PORES OF VARIOUS SIZES.
• AGGREGATES WILL ABSORB WATER WHEN IT IS DRY BUT
NORMALLY RELEASE WATER IN THE CONCRETE MIX WHEN IT IS
WET.
• THE AMOUNT OF WATER AND ITS RATE OF PERMEATION
DEPENDS ON THE SIZE AND VOLUME OF AGGREGATE
• SINCE THE AGGREGATE COMPRISES 75% OF THE CONCRETE
VOLUME, IT IS ESSENTIAL TO NOTE THAT POROSITY OF AN
AGGREGATE CONTRIBUTE TO THE OVERALL POROSITY OF
CONCRETE.
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20. 6. GRADING OF AGGREGATES:
• COARSE AND FINE AGGREGATES TO BE USED FOR MAKING CONCRETE
SHOULD BE WELL GRADED. GRADATION MEANS THE PARTICLE SIZE
DISTRIBUTION OF AGGREGATES. TEST FOR GRADING OF AGGREGATES
IS CARRIED OUT USING THE SIEVE ANALYSIS METHOD.
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Prepared by .. .
Kaushal Mehta … .. twitter@kaushalmehta96
Jigar Patel … .. twitter@jigarpatel_jp
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