1. CON 121
Concrete Aggregate
Session 4
Aggregate Testing

2. Aggregate Characteristics and
Tests
 The majority of the tests and characteristics
listed are referenced in ASTM C 33 (AASHTO
M 6/M 80).

3. Aggregate Characteristics and Tests (1)
Characteristic Test
ASTM C 131 (AASHTO T 96), ASTM C 535,
Abrasion resistance
ASTM C 779
F-T resistance ASTM C 666 (AASHTO T 161), ASTM C 682
Sulfate resistance ASTM C 88 (AASHTO T 104)
Particle shape and
ASTM C 295, ASTM D 3398
surface texture
Grading ASTM C 117 (AASHTO T 11), ASTM C 136
Void content ASTM C 1252 (AASHTO T 304)
Bulk density ASTM C 29 (AASHTO T 19)

4. Aggregate Characteristics and Tests (2)
Characteristic Test
ASTM C 127 (AASHTO T 85)—fine aggregate ASTM C
Relative density 128 (AASHTO T 84)—coarse aggregate
Absorption and ASTM C 70, ASTM C 127 (AASHTO T 85), ASTM C 128
surface moisture (AASHTO T 84), ASTM C 566 (AASHTO
Strength ASTM C 39 (AASHTO T 22), ASTM C 78
ASTM C 40 (AASHTO T 21), ASTM C 87 (AASHTO T 71),
Aggregate
ASTM C 117 (AASHTO T 11), ASTM C 123 (AASHTO T
constituents 113), ASTM C 142 (AASHTO T 112), ASTM C 295
ASTM C 227, ASTM C 289, ASTM C 295, ASTM C 342,
Alkali Resistance ASTM C 586, ASTM C 1260 (AASHTO T 303), ASTM C
1293

5. Harmful Impurities
 Organic Impurities
 Silt
 Clay
 Shale
 Iron Oxide
 Coal and Lignite Particles
 Lightweight and Soft Particles

6. Harmful Materials (1)
Substances Effect on Concrete Test Designation
Affects setting and hardening, & ASTM C40
Organic impurities
deterioration ASTM C 87
Materials finer than
Affects bond, increases water
the 75-µm (No. ASTM C117
requirement
200) sieve
Coal, lignite, or Lt- Affects durability, stains and
ASTM C123
materials popouts
Soft particles Affects durability ASTM C235

7. Harmful Materials (2)
Substances Effects on Concrete Test Designation
Clay lumps and Affects workability,
ASTM C 142 (AASHTO T 112)
friable particles durability, popout
Chert of <2.40 Affects durability, ASTM C 123 (AASHTO T 113)
relative density may cause popouts ASTM C 295
Causes abnormal ASTM C 227, C 289, C 295, C
Alkali-reactive expansion, map 342, C 586 C 1260, C 1293
aggregates cracking, and
popouts

8. Organic Impurities
 Delay Setting
 Reduce Strength Gain
 Materials Finer than 200 mesh may form
coating on aggregate particles
 Weaken Bond between paste and aggregate
 Increase Water Demand

9. Clay and Shale Impurities
 Absorb Mixing Water
 Cause Pop-Outs
 Affect Durability
 Affect Wear Resistance
 Break up during mixing and Increase water
demand
 Iron oxide particles will cause unsightly stains

10. Coal and Lignite Impurities
 Affect Durability of Concrete causing
Pop-Outs, Stains
 Affect Wear Resistance
 Soft Particles or friable particles break-up
during mixing
 Increased Water Demand

11. Particle Shape and Surface Texture
 Rough-textured, angular, elongated Particles
 Demand More Water
 Better Bonding
 Cause Pumping Problems
 Smooth and rounded Particles
 Less Bond
 Demand Less Water
 Void content between aggregates increase with
angularity

12. Fine Aggregate
 Particle Shape/Surface Texture

13. Bulk Density or Unit Weight
 Mass or weight of an aggregate per a specified unit
volume
 Normal weight concrete range 75-110 lb/cuft
 Void Content between particles affects paste content
 Coarse aggregate 30%-45%
 Fine aggregate 40%-50%

14. Relative Density or Specific Weight
 Ratio of aggregate mass to a mass of equal
absolute volume of water
 Used for mixture proportioning and control
 Natural aggregate relative density range 2.4-2.9
 Relative Density determined oven-dry or
saturated surface-dry (SSD)

15. Frost Resistance
 Important characteristic related porosity, absorption,
permeability, and pore structure
 Hydraulic pressure caused by freezing of water,
results in expansion causing disintegration of
concrete
 Cracking of concrete pavements to F-T deterioration
of aggregate is called D-cracking

16. D-Cracking
 D-cracking along a
transverse joint caused by
failure of carbonate coarse
aggregate.
 Fractured carbonate
aggregate particle as a
source of distress in D-
cracking.
 Cracking of concrete
pavements caused by the
freeze-thaw deterioration
of the aggregate within
concrete is called D-
cracking.

17. D-Cracking

18. Absorption and Surface Moisture
 Internal structure of an aggregate particle is made up
of solid matter and voids
 Various moisture conditions
 Oven dry-fully absorbent
 Air dry-dry at particle surface, but containing interior
moisture
 Saturated surface dry-neither absorbing or contributing
water
 Damp or wet-containing excess water
 Coarse and fine aggregates range 0.2%-4% and 0.2%-
2%, respectively

19. Moisture Conditions

20. Bulking of Sand
 Bulking is the increase total volume of moist
fine aggregate over the same dry mass
 Surface tension in the moisture holds particles
apart
 Caused when moved in a damp condition
 Weighting sand and adjusting for moisture
content when proportioning concrete

21. Bulking of Sand
 Surface moisture on
fine aggregate can
cause considerable
bulking; the amount
varies with the amount
of moisture and the
aggregate grading.

22. Alkali- Aggregate Reactivity
( AAR )
 is a reaction between the active mineral
constituents of some aggregates and the
sodium and potassium alkali hydroxides and
calcium hydroxide in the concrete.
 Harmful only when it produces significant
expansion
 Alkali-Silica Reaction (ASR)
 Alkali-Carbonate Reaction (ACR )

23. Alkali-Silica Reaction (ASR)
 Visual Symptoms
 Network of cracks
 Closed or spalled
joints
 Relative
displacements
 Cracking of concrete
from alkali-silica
reactivity

24. Alkali-Silica Reaction (ASR)

25. Harmful Reactive Substances
 Some Potentially Harmful Reactive Minerals,
Rock, and Synthetic Materials
 Several of the rocks listed (granite gneiss and
certain quartz formations for example) react very
slowly and may not show evidence of any
harmful degree of reactivity until the concrete is
over 20 years old.
 Only certain sources of these materials have
shown reactivity.

26. Harmful Reactive Substances
Alkali-silica reactive substances
Andesites Glassy or crypto- Quartzoses
Argillites crystalline Cherts
Certain siliceous volcanics Rhyolites
limestones and Granite gneiss Schists
dolomites Graywackes Siliceous shales
Chalcedonic cherts Opal Strained quartz and
Chalcedony Opaline shales certain other forms of
Cristobalite Phylites quartz
Dacites Quartzites Synthetic and natural
silicious glass

27. Harmful Reactive Substances
Alkali-carbonate reactive
substances
Calcitic dolomites
Dolomitic limestones
Fine-grained dolomites

28. Popouts
 A popout is the
breaking away of a
small fragment of
concrete surface due to
internal pressure that
leaves a shallow,
typically conical
depression.

29. Alkali-Silica Reaction (ASR)
 Visual Symptoms (cont.)
 Fragments breaking out of the
surface (popouts)
 Popouts cased by ASR of sand-
sized particles. Inset shows
close-up of a popout.
 Mechanism
1. Alkali hydroxide + reactive
silica gel reaction
product (alkali-silica gel)
2. Gel reaction product +
moisture expansion

30. Alkali-Silica Reaction (ASR)
 Polished section view of an alkali
reactive aggregate in concrete.
 Observe the alkali-silica reaction
rim around the reactive
aggregate and the crack
formation.
 Influencing Factors
 Reactive forms of silica in the
aggregate,
 High-alkali (pH) pore solution
 Sufficient moisture
If one of these conditions is absent ― ASR cannot occur.

31. Alkali-Silica Reaction (ASR)
Test Methods
Mortar-Bar Method ASTM 227
Chemical Method ASTM C 289
Petrographic Examination ASTM C 295
Rapid Mortar-Bar Test ASTM C 1260 OR AASHTOT 303
Concrete Prism Test ASTM C 1293

32. Alkali-Silica Reaction (ASR)
 Controlling ASR
 Non-reactive aggregates
 Supplementary cementing materials or blended
cements
 Limit alkali loading
 Lithium-based admixtures
 Limestone sweetening (~30% replacement of
reactive aggregate with crushed limestone

33. Alkali-Carbonate Reaction (ACR)
 Influencing factors
 Clay content, or insoluble residue content, in the
range of 5% to 25%
 Calcite-to-dolomite ratio of approximately 1:1
 Increase in the dolomite volume
 Small size of the discrete dolomite crystals
(rhombs) suspended in a clay matrix

34. Alkali-Carbonate Reaction
 Test methods
 Petrographic examination (ASTM C 295)
 Rock cylinder method (ASTM C 586)
 Concrete prism test (ASTM C 1105)

35. Alkali-Carbonate Reaction
 Controlling ACR
 Selective quarrying to avoid reactive aggregate
 Blend aggregate according to Appendix in
ASTM C 1105
 Limit aggregate size to smallest practical

36. Aggregate Testing
Please return to Blackboard and watch the
following videos:
 Video 1: Particle Shape and Surface Texture
 Video 2: Specific Gravity
 Video 3: Unit Weight & Voids
 Video 4: Absorption