This document discusses concrete aggregates, which are divided into fine and coarse sizes. Fine aggregates are less than 5 mm and usually make up 35-45% of concrete. Coarse aggregates are larger than 5 mm. Aggregates come from various rock and mineral sources including igneous, sedimentary, and metamorphic rocks. Normal weight aggregates produce concrete weighing 2200-2400 kg/m3. Lightweight aggregates produce lower density concrete. Processing involves crushing, screening, washing, and techniques like heavy media separation to beneficiate aggregates.

1. CON 121
Concrete Aggregate
Session 1
Introduction

2. Range of Aggregate Sizes
Range of particle sizes found in aggregate for use in concrete

3. Fine Aggregate
 Sand and/or crushed
stone
 < 5 mm (0.2 in.)
 F.A. content usually
35% to 45% by mass or
volume of total
aggregate

4. Coarse Aggregate
 Coarse aggregate.
Rounded gravel (left)
and crushed stone
(right)
 Gravel and crushed
stone
 5 mm (0.2 in.)
 typically between 9.5
and 37.5 mm (3/8 and
1½ in.)

5. Rock and Mineral Constituents
in Aggregates
1. Minerals
2. Igneous rocks
3. Metamorphic rocks
4. Sedimentary rocks

6. Rock and Mineral Constituents in Aggregates
(Minerals)
 Silica  Sulfate
 Quartz, Opal  Gypsum, Anhydrite
 Silicates  Iron sulfide
 Pyrite, Marcasite
 Feldspar, Clay
 Iron oxide
 Carbonate
 Magnetite, Hematite
 Calcite, Dolomite

7. Rock and Mineral Constituents in Aggregates
(Igneous Rocks)
 Granite  Pegmatite
 Syenite  Volcanic glass
 Diorite  Felsite
 Gabbro  Basalt
 Peridotite

8. Rock and Mineral Constituents in Aggregates
(Sedimentary rocks)
 Conglomerate
 Sandstone
 Claystone, siltstone,
argillite, and shale
 Carbonates
 Chert

9. Rock and Mineral Constituents in Aggregates
(Metamorphic rocks)
 Marble  Amphibolite
 Metaquartzite  Hornfels
 Slate  Gneiss
 Phyllite  Serpentinite
 Schist

10. Normal-Weight Aggregate
ASTM C 33
Most common
aggregates
 Sand Produce normal-weight concrete
2200 to 2400 kg/m3 (140 to 150 lb/ft3)
 Gravel
 Crushed stone

11. Lightweight Aggregate (1)
ASTM C 330
Expanded
 Shale
 Clay
 Slate
 Slag
Produce structural lightweight concrete
1350 to 1850 kg/m3 (90 to 120 lb/ft3)

12. Lightweight Aggregate (2)
 Pumice
 Scoria
Produce lightweight insulating
 Perlite concrete— 250 to 1450 kg/m3
 Vermiculite (15 to 90 lb/ft3)
 Diatomite

13. Heavyweight Aggregate
ASTM C 637, C 638 (Radiation Shielding)
 Barite
 Limonite Produce high-density concrete up
 Magnetite to 6400 kg/m3 (400 lb/ft3)
 Ilmenite
 Hematite
 Iron
 Steel punchings or shot

14. Aggregate Processing
 Basic Processing
 Crushing
 Screening
 Washing
 Benefication
 Heavy media separation
 Jigging
 Rising-current classification
 Crushing

15. Concrete Aggregates
Please return to Blackboard and watch the
following videos:
 Video 1: Concrete Aggregates
 Video 2: Aggregate Benefication