Aggregate

Pic.. In aggregate working

introduction Aggregate can be defined as a

material that is used as filler for filling up the voids during construction. It comprises of a broad category of coarse material that is used in construction. Aggregates are the most mined category of minerals in the world. They have been in use for thousands of years with significant use taking place back during the Roman Empire. The invention of concrete resulted in demand for aggregate since it is a crucial material for preparation of concrete.

principale

Working Principle of AggregateAggregates impart strength by reinforcing

the composite material, that is to say, they fill up the voids to form a substance that has more compressive strength. By filling up the space that is available, aggregate ensures that the structure doesn’t fail when load is applied to the structure.

Main Types of aggregate

Types of Aggregate SandGravelSlagGeo-synthetic Aggregates andCrushed stoneGranular materialRecycled concrete

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Application

Applications of Aggregate FoundationsFrench DrainsSeptic Drain FieldsRetaining Wall DrainsFoundationsRoadsRailroadsConcrete Constituent

Measures of aggregate size

Precautionary Measures Make sure that

segregation of aggregate does not occur.

Depending upon its usage, it should be dry/wet.

Make sure that it has passed the sieve size test and is correctly graded.

Different applications require different standards of aggregates; be wary of that.

AggregateAggregate

Based on Unit weight

Normal

Sand, gravel, crushed rocks, granite, basalt

Light weight

Broken bricks, air cooled slag, bloated clay

Hevy weight

Barite, Magenetite , limonite, hematite

Based on size

Fine

coarse

Based on shape

Rounded, irreguler, angular falky, elongated

Based on texure

Glassy, smooth, grannuler, crystaline etc..

Types of aggegates

o Classification of aggregate based on unit weight

1. Normal weight aggregates 2. Light weight aggregates 3.Hevy weight aggregateso Classification of based on size 1. fine aggregate 2. coarse aggregate

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o Classification based on shape 1.Rounded aggregate 2.irreguler aggregate 3.Flaky aggregate 4.Elongated aggregateo Classification based on texure Glassy : black , fint smooth: chert , slaet , marble , some

rhyolite Granular: sandstone , oolites crystalline: fine ,midiume , coarse Honeycombed and prous: scoria , pumice

trass

Classification of aggregate based on unit weight

1. Normal aggregates Normal weight aggregate can be used in all

types of works. The specific grevity of these aggregate is about

1.5 to 2.7. The density of concrete produce using is about

2300kg/m3 to 2600kg/m3 . Natural aggregates

SandGravel

crushed rock as greniteBasaltQuartziltSandston

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Artificial aggregatesBroken bricksAir cooled slagsintered fly-ashBloated clay

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2. Light weight aggregate Natural agg. pumiee scoria

rise husksaw dust

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Aetificial aggregatefoamed slagbloated clayexpanded shalesintered fly ash

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3. Hevy weight aggregatebaritemagnetitelimonitehematite

Classification based on size

1.Fine aggregate (F.A) The size of aggregate 4.75mm and

smaller is called fine aggregate2. Coarse aggregate (C.A) The size of aggregate bigger then 4.75

mm is called coarse aggregate

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Fine aggregate

•Size <4.75 mm• Bulking is more (up to 40%)•F.A fills voids between C.A•Eg. Natural sand, stone Coarse

aggregate

•Size >4.75 mm•Bulking is very small & neglected.•C.A gives strength to concrete•Eg. Gravel , crushed stone