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Material for Civil Engineering

aggregates

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Definition

Materials (for construction) Inert material which, when bound together into a

conglomerated mass by a matrix, form: -concrete, -mastic mortar, -plaster.

An aggregation of sand, gravel, crushed stone, slag or other material composition used in combination with a binding medium to form: -bituminous and Portland cement, -concrete, -macadam, -mastic, -mortar cement, -plaster, or alone as: -railroad ballast, -filter beds, and -various manufacturing processes such as fluxing

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Classification

Natural Aggregate

Manufactured Aggregate

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Natural Aggregates

Taken from natural deposits without change in their nature during production, with the exception of crushing, sizing, grading or washing

Includes: pumice, shells, iron ore, lime rock

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Manufactured Aggregates

Aggregates produced as a direct product, rather than as a by-product of a manufacturing process

Includes: Blast furnace slag Clay Shale; Light weight aggregates

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Synthetic – Artificial Aggregates

By-product of an industrial process

Product of process developed to manufactured aggregate with special properties

Reclaimed or waste construction materials

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Classification based on Size

FINE Aggregate passing 9.5mm (3/8”) sieve, passing sieve no 4 (4.75mm)

and predominantly retained on 75u (no 200) sieve Aggregate passing no 4 and retained on the no 200 (75um) sieve

COARSE

Aggregate predominantly retained on the no 4 sieve (for Portland Cement Concrete)

The no 8 or no 10 sieve (for bituminous concrete)

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Composition & Structures

Natural Aggregates

Consist of naturally occurring material of mineral composition

Derived from rocks with single mineral or several different mineral

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NATURAL AGGREGATES

METAMORPHIC ROCK

IGNEOUS ROCK

SEDIMENTARY ROCK

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Composition & Structures

IGNEOUS ROCK

COOL MELTING FORMED (ABOVE OR BELOW THE

EARTH’S SURFACE)

CONSISTS OF CRYSTAL OR MINERALS IN A

CRYSTALLINE (OR GLOSSY) MATRIX

SIZE IS A FUNCTION OF COOLING RATE

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Composition & Structures

SEDIMENTARY ROCK

FORMED BY THE CONSOLIDATION OF

DEPOSITS, - WEATHERING PRODUCTS AND

EROSION OF ROCKS (EARTH SURFACE)

LESS MECHANICAL COMPACTIONS

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Composition & Structures

METAMORPHIC ROCK

FORMED BY THE APPLICATION OF INTENSE HEAT

AND PRESSURE TO SEDIMENTARY ROCKS

LESS POROUS, STRONG MATRIX

(RECRYSTALLIZATION)

STRONGED AND LESS ANISOTROPIC COMPACTED

TO SEDIMENTARY ROCKS

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ROCKS TYPE Specific Gravity

POROSITY (% - vol)

IGNEOUS BasaltGranite

2.6 – 3.02.6 – 3.0

50 – 200100 – 250

SEDIMENTARY ShaleLimestoneSandstone

2.0 – 2.72.3 – 2.82.2 – 2.7

10 – 100 35 – 250 20 – 175

METAMORPHIC StateMarbleQuartzite

2.6 – 2.92.6 – 2.82.6 – 2.7

100 – 200100 – 250100 - 300

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Principles and Procedures

The use and process: QUALITY : high (estimate) COST : low (estimate)

The procedures: Excavation Transportation Washing Crushing Sizing

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procedures

Processing plant

Site

Transportation (truck, rail, conveyor belt)

Washing : before and/or after

Excavator: digging

Removal of organic material (silt; clay; leaves; mud)

Method: blasting; dragging; pumping

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Sizing and screening

1. Sizing: by crusher

2. Proper and desirable size

3. Crusher type:

size of designed aggregate

Sieve : vibratory screen

Set of sieves with designated diameter

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d

sieve

d

D

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Sieve analysis

h

D

X gram

(X- z) gram

Retained = coarser

X’ gram coarser

X” gram finer

X”‘ gram finer

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Grain distribution

10 1 0.1 0.01 0.0.01

0

20

60

80

100%

by w

eig

ht

finer

Diameter, log, mm

40

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End of session