ML12153A332
| ML12153A332 | |
| Person / Time | |
|---|---|
| Issue date: | 06/01/2012 |
| From: | Office of the Chief Human Capital Officer |
| To: | |
| References | |
| Download: ML12153A332 (87) | |
Text
s Codes Codes gy and gy and Aggregate Geology Aggregate Geology hnolog hnolog and Classification and Classification te Tech te Tech Concret Concret C
Aggregate Geology and Aggregate Geology and Classification Brief concrete overview Aggregate mineralogy and geology Aggregate mineralogy and geology Aggregate production Physical properties of aggregates
Cement Water Air Fine Aggregate 60 60 75%
f l
75%
f l
60 60 -- 75% of volume 75% of volume is stone & sand is stone & sand Coarse Aggregate
ACI 221R Guide for Use of Normal Weight and Heavyweight Aggregates in Concrete in Concrete Aggregates, the major constituent of concrete, influence the properties and performance of both influence the properties and performance of both freshly mixed and hardened concrete. In addition to serving as an inexpensive filler, they impart certain b
f h
d b d h
d positive benefits that are described in this guide.
When they perform below expectation, unsatisfactory concrete may result. Their important role is frequently y
p f
q y
over-looked because of their relatively low cost as compared to that of cementitious materials.
Aggregate in Concrete Coarse Aggregate Aggregate in Concrete (stone or gravel)
> 5 mm (0.2 in.)
Largest particles may range from 0.5 mm ( in.) to 37.5 mm (11/2 in.) or more Fine Aggregate (sand)
(sand)
< 5 mm (0.2 in.)
Influence of Aggregate on h
Fresh Concrete Properties Aggregate Property Concrete Property Aggregate Property Concrete Property Particle size distribution (grading)
Workability Water demand Particle shape Particle texture Presence of fine material Paste content (silt & clay)
Organic impurities Setting behavior
Influence of Aggregate on Hardened Concrete Properties Aggregate Property Concrete Property Aggregate Property Concrete Property Size and shape Strength Mechanical behaviour Strength Stiffness Organic impurities Modulus of elasticity Shrinkage Coefficient of thermal expansion Coefficient of thermal expansion Thermal conductivity Thermal conductivity Specific heat Specific heat Thermal diffusivity Thermal diffusivity
Influence of Aggregate on Hardened Concrete Properties Aggregate Property Concrete Property Aggregate Property Concrete Property Soundness Frost resistance Resistance to freezing and thawing Particle size Presence of alkali-reactive minerals Resistance to alkali-aggregate reaction Density Porosity l
b l Abrasion resistance Frictional properties (pavements) h Volume stability Mineral composition Aesthetics Economics
Aggregate Geology Aggregate Geology
Aggregate Geology Aggregate Geology Mi l
lid t lli b t Mineral-solid crystalline substance, formed by natural, and usually inorganic, processes processes Homogeneous physical properties Distinctive chemical composition Distinctive chemical composition Distinct crystal structure Rock-natural assemblage of one or more Rock - natural assemblage of one or more minerals
Mineral Classification C
t ll h
Mineral Classification Crystallography Physical properties Crystal habit Cleavage Density Optical properties Hardness Color Electrical properties Magnetic properties Chemical composition
Mineral Classification by Chemical Composition Systematic Mineralogy Native elements Halides Nitrates Carbonates Borates Organic Substances Phosphates Arsenates Vanadates Silicates Sulfides Oxides Hydroxides Sulfates Chromates Tungstates Molybdates
Mineral Classification by Chemical Composition Systematic Mineralogy Native elements Halides Nitrates Carbonates Borates Organic Substances Phosphates Arsenates Vanadates Silicates Sulfides Oxides Hydroxides Sulfates Chromates Tungstates Molybdates
Rock Classification Rock Classification R
k l
ifi d b d
f f ti Rocks classified by mode of formation Igneous Sedimentary Metamorphic
Igneous Rocks Igneous Rocks F
d b lidifi ti d
t lli ti f
Formed by solidification and crystallization of cooling magma (intrusive) or lava (extrusive)
Igneous Rocks Igneous Rocks I t i
i k
Intrusive igneous rocks form slowly h
i d t t
have a coarse-grained texture Extrusive igneous rocks l d f dl solidify more rapidly have a fine-grained texture
Igneous Rocks Igneous Rocks Intrusive Extrusive Major Minerals Minor Minerals Granite Rhyolite Quartz, K-feldspar, Na-feldspar Muscovite, biotite, amphibole p
p Syenite Trachyte K-feldspar, Na-feldspar Quartz, muscovite, biotite, amphibole Q
t N f ld K f ld C
Granodiorite Dacite Quartz, Na-feldspar, amphibole K-feldspar, Ca-feldspar, biotite Diorite Andesite Na-feldspar, Ca-f ld hib l Pyroxene, biotite feldspar, amphibole y
Gabbro/
Diabase Basalt Ca-feldspar, pyroxene, olivine Na-feldspar, amphibole
Sedimentary Rocks Sedimentary Rocks D t it l di t
k Detrital sedimentary rocks Chemical sedimentary rocks
Sedimentary Rocks Sedimentary Rocks D t it l di t
k Detrital sedimentary rocks Formed by deposition and lithification of k
d i
l f t
rock and mineral fragments Deposition results from weathering and t
t f i ti k
transport of existing rocks Lithification occurs through compaction d/
t ti and/or cementation Classified mainly by particle size
Sedimentary Rocks Sedimentary Rocks l
(
)
Particle Name Size (mm)
Boulder
> 256 Cobbles64-256 Pebble 4-64 Granule 2-4 Sand 0.062-2 Silt 0.004-0.062 Clay
< 0.004
Sedimentary Rocks Sedimentary Rocks Sediment Particle Name Size (mm)
Sediment Name Detrital Rock Boulder
> 256 Conglomerate Gravel Conglomerate (rounded particles)
Breccia
(
l i l
)
Cobbles64-256 Pebble 4-64 (angular particles)
Granule 2-4 Sand 0.062-2 Sand Sandstone Silt 0.004-0.062 Mud Siltstone Claystone Argillite Mudstone Clay
< 0 004 g
Shale Clay
< 0.004
Sedimentary Rocks Sedimentary Rocks Sandstones classified by:
Sandstones classified by:
Particle sorting P
ti l h
Particle shape Particle mineralogy l
Cementing material calcite silica silica iron oxide
Sedimentary Rocks Sedimentary Rocks D t it l di t
k Detrital sedimentary rocks Chemical sedimentary rocks Inorganic Organic
Sedimentary Rocks Sedimentary Rocks Chemical sedimentary rocks Inorganic Precipitation of dissolved Precipitation of dissolved material from solution (calm lakes and seas) limestone-travertine, oolitic limestone dolostone dolostone chert rock salt (halite) rock gypsum
Sedimentary Rocks Sedimentary Rocks Chemical sedimentary rocks Organic Biochemical sediment Biochemical sediment formed by skeletons of marine organisms coquina chalk coral reefs coral reefs chert Coal peat anthracite
Metamorphic Rocks Metamorphic Rocks F
d b t f
ti f
i ti Formed by transformation of preexisting rocks exposed to immense heat and/or pressure pressure Original rock undergoes mineralogical and textural changes textural changes Granite Gneiss
Rock Classification Rock Classification Rocks Igneous Sedimentary Metamorphic Intrusive Extrusive Detrital Chemical Intrusive Extrusive Detrital Chemical Inorganic Organic
The Rock Cycle The Rock Cycle Magma Melting Cooling and solidification (Crystallization)
Igneous Rock Metamorphic R
k Heat and pressure Rock Rock Weathering, t
t ti transportation, and deposition Heat and pressure (Metamorphism)
Sedimentary Rock Sediment Weathering, transportation, deposition Cementation and compaction (Lithification)
Rocks for Use in Concrete Rocks for Use in Concrete ASTM C294 St d
d D i ti ASTM C294: Standard Descriptive Nomenclature for Constituents of Concrete Aggregates granite diorite gabbro limestone Aggregates Common, naturally occurring rock types granite, diorite, gabbro fine-grained volcanic rocks basalt (traprock) l d
limestone chert marble
(
)
conglomerate, sandstone, (ortho)quartzite, arkose graywacke (meta)quartzite gneiss slate, phyllite, schist siltstone, claystone, shale
Rocks for Use in Concrete Rocks for Use in Concrete ASTM C295 St d
d G id f ASTM C295: Standard Guide for Petrographic Examination of Aggregates for Concrete Concrete X-ray diffraction X
fl X-ray fluorescence
Potentially Deleterious Constituents Ch l d
i h
t Chalcedonic chert (ASR)
Argillaceous dolomitic limestone (ACR)
Aggregate Production
Aggregate Production Aggregate Production N t l
d d
l Natural sand and gravel Crushed rock
Aggregate Production Aggregate Production N t l
d d
l Natural sand and gravel usually dug or dredged from pits, rivers, lakes or seabeds lakes or seabeds often require minimal processing tend to be smooth and rounded tend to be smooth and rounded
Aggregate Production Aggregate Production C
h d k
Crushed rock typically produced by crushing quarried rock or cobbles and boulders rock or cobbles and boulders tend to be sharp and angular
Aggregate Production Aggregate Production Crushed Rock Initial processing to obtain suitable grading, uniformity and cleanliness uniformity and cleanliness
- 1. Crushing 2
Screening
- 2. Screening
- 3. Washing A
t Aggregate beneficiation
Aggregate Production Aggregate Production Crushed Rock
- 1. Crushing
Aggregate Production Aggregate Production Crushed Rock
- 1. Crushing
Aggregate Production Aggregate Production Crushed Rock
- 1. Crushing
Aggregate Production Aggregate Production Crushed Rock
- 2. Screening-Vibrating screens
Aggregate Production Aggregate Production Crushed Rock
- 2. Screening-Cylindrical revolving screens
Aggregate Production Aggregate Production Crushed Rock
- 3. Washing
Aggregate Production Aggregate Production Crushed Rock Aggregate beneficiation l i i
h d d
applying processing methods to upgrade the quality of the aggregates typically involves removal of undesirable typically involves removal of undesirable or deleterious particles
Aggregate Production Aggregate Production Crushed Rock Aggregate beneficiation Treatment Objective Crushing Remove friable particles Heavy media separation Remove lightweight particles Reverse air or water flow Remove lightweight particles Hydraulic jigging Remove lightweight particles Elastic fractionation (bounce)
Remove lightweight and soft particles Washing and scrubbing Remove coating and fines Blending Control deleterious components Screening Control gradation
Aggregate Production Aggregate Production Crushed Rock Aggregate beneficiation
Aggregate Storage and Aggregate Storage and Handling Build stockpiles in thin layers of uniform thickness thickness
Aggregate Storage and Aggregate Storage and Handling Retrieve samples from edges of pile, bottom to top bottom to top
Aggregate Storage and Aggregate Storage and Handling Stockpiling separate size fractions can minimize segregation of coarse aggregates minimize segregation of coarse aggregates
Aggregate Storage and Aggregate Storage and Handling Damp sand segregates less than dry sand
Aggregate Storage and Aggregate Storage and Handling Crushed aggregate segregates less than rounded aggregate rounded aggregate
Aggregate Storage and Aggregate Storage and Handling Bulkheads or dividers minimize cross-contamination of stockpiles contamination of stockpiles
Aggregate Physical Aggregate Physical Properties Properties
Aggregate Physical Aggregate Physical Properties p
Particle shape and surface texture Bulk density and relative density Bulk density and relative density Absorption and surface moisture Shrinkage g
Strength and hardness Thermal properties Grading Resistance to freezing and thawing Volume stability Volume stability Abrasion and skid resistance Resistance to corrosive substances
Particle Shape Particle Shape Cl ifi i
Classifications Rounded Irregular Angular g
Flat Elongated Elongated Flat and elongated
Particle Shape Particle Shape
Particle Shape Particle Shape Discoidal Sub Spherical Sub Prismoidal Discoidal Sub-discoidal Spherical Sub-prismoidal Prismoidal FLAT ELONGATED
Particle Shape Particle Shape Fl d l d
i l Flat and elongated particles Significantly affect workability and pumpability May trap bleedwater and contribute to mortar flaking mortar flaking Limited to less than 15% of total aggregate 15% of total aggregate mass
Surface Texture Surface Texture Cl ifi i
Classifications Glassy Smooth Granular Rough Crystalline Crystalline Honeycomb
Surface Texture Surface Texture Smooth Surface
Surface Texture Surface Texture Rough Surface
Particle Shape & Surface Particle Shape & Surface Texture Can significantly affect fresh concrete properties R
h l
ti l Rough, angular particles:
Have more interparticle interaction and greater resistance to movement
Require more lubrication (paste & water)
Have larger surface-to-volume ratio R
i t t t
t
Requires more paste to coat aggregate
Generally achieve improved bond with cement paste
Generally provide greater flexural strength
Particle Shape & Surface Particle Shape & Surface Texture ASTM D4791: Standard Test Method for Flat Particles Elongated Particles or Flat and Elongated Particles, Elongated Particles, or Flat and Elongated Particles in Coarse Aggregate
Particle Shape & Surface Particle Shape & Surface Texture ASTM C1252: Standard Test Method for Uncompacted Method for Uncompacted Void Content of Fine Aggregate (as Influenced by P
ti l Sh S
f Particle Shape, Surface Texture, and Grading)
Bulk Density Bulk Density Al ll d it i ht Also called unit weight Mass or weight of t
it l
aggregate per unit volume Volume occupied by both aggregate ti l d
id b t ti l particles and voids between particles Void content:
30 to 45% for coarse aggregate 40 to 50% for fine aggregate
Bulk Density Bulk Density A
l it i id t
t Angularity increases void content Large top size, even gradation decreases id i
b lk d it voids, increases bulk density Normal-weight: 1200 to 1700 kg/m3 (75 t 110 lb/ft3)
(75 to 110 lb/ft3)
ASTM C29: Standard Test Method for Bulk D
it (U it W i ht) d V id i Density (Unit Weight) and Voids in Aggregate
Bulk Density Bulk Density
Relative Density Relative Density Al ll d ifi it Also called specific gravity Ratio of mass of aggregate to equal volume f
t of water Used in absolute volume method of mix d
i design Normal-weight: 2.4 to 2.9
Relative Density Relative Density (Mass Density)
Mass density is product of specific gravity and density of water y
O H
agg 2
Density x
S.G.
Density
=
3 3
3 agg ft lb 156 m
kg 2500 m
kg 1000 x
2.5 Density
=
=
=
Normal-weight: 2400 to 2900 kg/m3 (150 to 181 lb/ft3)
(150 to 181 lb/ft )
Mass density does not account for volume of voids between particles of voids between particles
Relative Density Relative Density ASTM C127 St d
d T t M th d f ASTM C127: Standard Test Method for Density, Relative Density (Specific Gravity),
and Absorption of Coarse Aggregate and Absorption of Coarse Aggregate ASTM C128: Standard Test Method for Density Relative Density (Specific Gravity)
Density, Relative Density (Specific Gravity),
and Absorption of Fine Aggregate
Absorption and Surface Absorption and Surface Moisture Oven dry Aggregate contains Saturated surface dry (SSD) gg g
no moisture (pores are empty)
Fully absorbent dry (SSD)
Aggregate is saturated (pores are filled), but there is no free water th f
on the surface At equilibrium Air dry Aggregate contains some moisture, but is t
t t d (
Damp or wet Aggregate is saturated (pores are filled), and th i
f not saturated (pores are partially filled)
Somewhat absorbent there is an excess of water on the surface Contributing free water
Absorption and Surface Absorption and Surface Moisture Moisture conditions Mix water ASTM C127 and C128 Absorption mass % of water to reach SSD Coarse aggregate: 0.2 to 4%
Fine aggregate: 0.2 to 2%
Free water content of moist aggregates Coarse aggregate: 0.5 to 2%
Fine aggregate: 2 to 6%
Absorption and Surface Absorption and Surface Moisture Bulking Increase in total volume of fine aggregate when moist d
compared to same mass when dry Stockpile dry Stockpile partially saturated Stockpile saturated
Absorption and Surface Absorption and Surface Moisture Bulking Can cause batching errors Effect more prominent with fi d
i finer gradations
Shrinkage-Aggregates Shrinkage-Aggregates Often related to absorption characteristics Often related to absorption characteristics High absorption high shrinkage Low shrinkage aggregates Low shrinkage aggregates Quartz Limestone Feldspar Dolomite Granite High shrinkage aggregates Sandstone Shale Slate Graywacke Hornblende Hornblende
Shrinkage-Concrete Shrinkage-Concrete
Shrinkage-Concrete Shrinkage-Concrete I fl d b t
h t
i ti Influenced by many aggregate characteristics Stiffness, compressibility, modulus of elasticity G
di ti l h
t t i
Grading, particle shape, aggregate top size Paste-aggregate bond (texture, porosity)
Presence of clay on or within aggregate Presence of clay on or within aggregate
Aggregate Strength Aggregate Strength C
i 65 t 270 M (10 000 t Compressive: 65 to 270 Mpa (10,000 to 40,000 psi)
T il 2 t 15 M (300 t 2 300 i)
Tensile: 2 to 15 Mpa (300 to 2,300 psi)
Does not usually influence normal-strength t
concrete Rarely tested directly Paste hardness and paste-aggregate bond more critical
Aggregate Hardness Aggregate Hardness Mohs scale for minerals Mohs scale for minerals Relative Scale Mineral Common Object Hardest 10 Diamond 9
Corundum 8
Topaz 7
Quartz 6
Potassium feldspar Glass, pocket knife (5.5) 5 Apatite 4
Fluorite 3
Calcite Copper penny (3) 2 Gypsum Fingernail (2.5)
Softest 1
Talc
Aggregate Hardness Aggregate Hardness H
d t tif f k
Hard to quantify for rocks Varies with rock type Soft and friable particles Prone to crumbling Increase fines content ASTM C33 limits mass %
Will affect abrasion resistance
Aggregate Thermal Aggregate Thermal Properties p
Coefficient of thermal expansion (CTE) 1 16 10 6/°C ( 2 29 10 6/° )
~1 to 16 x10-6/°C (~2 to 29 x10-6/°F)
CTE of paste and aggregate vary greatly St l i fl CTE f t
Strongly influences CTE of concrete Conductivity Diffusivity Properties depend somewhat on aggregate mineralogy
Aggregate and Fire Aggregate and Fire Resistance Manufactured and lightweight aggregates have better insulating properties have better insulating properties provide greater fire resistance resistance Quartz expands 0.85%
at ~570°C (1060°F) at 570 C (1060 F) concrete with calcareous coarse aggregate often exhibits less damage after fire than concrete with siliceous aggregate
Summary Summary A
t i
60 t 75% f t
Aggregates comprise 60 to 75% of concrete volume A
t i fl f
h d h d
d Aggregates influence fresh and hardened concrete properties
Summary Summary R
k t
ll i
bl Rocks are naturally occurring assemblages of one or more minerals R
k d b d
f f ti Rocks grouped by mode of formation Igneous S di t
Sedimentary Metamorphic
Summary Summary A
t t ft t
l d
d Aggregates most often natural sand and gravel, or crushed rock A
t i ft d t hi Aggregate is often processed to achieve desired quality, uniformity, and gradation
Summary Summary Ph i
l ti f
t i l d Physical properties of aggregate include:
Particle shape and surface texture B lk d it d
l ti d
it Bulk density and relative density Absorption and surface moisture Shrinkage Shrinkage Strength and hardness Thermal properties Thermal properties
Summary Summary Ph i
l ti f
t Physical properties of aggregate may influence mix design process and overall properties of concrete properties of concrete