effects of blasting and the engineering properties of aggregates

8/3/2019 Effects of Blasting and the Engineering Properties of Aggregates

1/62

Effects of Blasting on the

Engineering Properties ofAggregates

Stan VittonAssociate Professor

Civil & Environmental Engineering

Michigan Technological University


2/62

Effects of Blasting on theEngineering Properties of

Aggregates

Introduction

High Strain Rate Effects

Crushing & Grinding

Dynamic Fracture

Conclusions


3/62

Jakes Law

Anything hit with a big

enough hammer will fallapart


4/62

Project Plowshare 1950sPeaceful use of nuclear weapons


5/62

Related Dynamic AggregateResearch

Petroleum Coke Crushing

Aggregate Interlock PCC Pavements

Vibration Effects of Green Concrete


6/62

Aggregate Interlock Test Setup

0.50 inch

3 kip

3 kip

NormalForceReaction

Test Frame


7/62

Concrete Fracture Device


8/62

Aggregate Interlock System

Vertical Actuator(Shear loading)

Horizontal Actuator(Normal resistance)

a

a

projectedface

Load-bearing holder


9/62



10/62



11/62

Blasting Effects on GreenConcrete

Little is known about the effects of blast vibrationson green concrete (less than 24 hours old)

Specification limitations: Engineers want a project done correctly

Contractors want to make money and be safe

Owners want a project done quickly, correctly, and

inexpensively

Politicians want to ensure public safety and protectpublic interests, while cutting budgets and personnel


12/62

Reasons

Fast track scheduling

Construction areas arebecoming more dense

Quarries are subjected tourban encroachment

Society is becoming morelitigious


13/62

Previous Studies

Hulshizer No critical limitfound, but set max to 2-4 in/sdepending on age

Hong Kong - Damage happensat large intensities by impact(100+ in/s)

OriardDoesnt see damagebut sets limit to 4 to 6 in/s, onage and distance

Howes 5 in/s had nodetrimental affect


14/62

Time of Concrete Mixing

Used thermocouplesPlaced in concretecylinders

Compare to ambienttemperature

Maturity occurs wheninternal temperaturereturns to ambient


15/62

Concrete Maturity Curve

60

70

80

90

0 5 10 15 20 25 30 35

Time (Hrs)

Temp(F)

Cylinder #2 Cylinder #1 Cylinder #3 Cylinder #4 Ambient

Open

Door


16/62

Project Site: Turunen Quarry

Located Near Pelkie, MI

Active Limestone/Dolomite Quarry

Work Area


17/62

Blast Components

BlastingCaps

Explosives

Hole Loading

Seismometers


18/62

Site Characterization

Load Hole

Place

Seismometers

DetonateShot

Cleanup


19/62

Sample Preparation - Field Batch

Components

MixComponents5-2-4 Minutes

ConsolidateConcrete at10,500 rpm

(175 Hz)

PlaceContainers atAppropriateSite


20/62

Conclusions

There is generally no difference in the meansof the data

More evidence supports a gain of strength at

2 hours than a loss at any other age Weak bonds may be broken and concrete

experiences self-healing

Vibrations up to 10.6 in/s MPRV have little orno detrimental affect on this mixof greenconcrete


21/62


Aggregates

Introduction


Crushing & Grinding

Dynamic Fracture

Conclusions


22/62

Strain Rate Sensitivity?

Aluminum

Steel

Geologic Materials

Ceramics


23/62

Dynamic Effects??Strain Rate??

o

L

Strain L

StrainStrain Rate Time

L

Lo


24/62

Dynamic Strength

Strain Rate

Strength

10-6/second

ASTM Concrete

Testing

102/second

Blasting

100/sec


25/62


26/62

Why?

Slow Fast


27/62

Why?

Slow Fast


28/62

Split Hopkinson Pressure BarEquipment Setup

StrikerBar

Incident Bar Transmission Bar

Specimen

Nicolet Digital Oscilloscope

WheatstoneBridge


29/62

Three-inch Split Hopkinson Pressure Bar


30/62

Split Hopkinson Pressure Bar

Transmission Bar Incident Bar Striker

Concrete Specimen

Strain Gages


31/62

Dynamic Compression Testing

SHPB was used

35psi chamber pressurefired striker bar

Pennies were used totransform square wave totriangular wave

Specimens completelycrushed

Data collected usingoscilloscope

60 Specimens tested


32/62


Aggregates

Introduction


Crushing & Grinding

Dynamic Fracture

Conclusions


33/62


34/62

Various Crushing & GrindingUnits


35/62

Cone, Jaw, Hammer Crushers


36/62

Vertical Shaft Impact (VSI)Crusher


37/62

Crushing & Grinding - Aggregate

Crushing

Hammer

Cone Jaw

VSI

Grinding

LA Abrasion

Micro-Deval

Aggregate Interlock(PCC)

Handling & Storage

Resilient Modulus

Friction-Polishing

Effects of Blasting on Rock


38/62

Effects of Blasting on RockRecent International Society of ExplosiveEngineers (2001-2004):

The Effects of Blasting on Crushing and GrindingEfficiency and Energy Consumption

Effects of Blasting on the Strength of Rock Fragmentation

Small Scale Study of Damage Due to Blasting andImplication on Crushing and Grinding

Effects of Blasting on the Strength of Rock Fragments

Degree of Fragmentation Under High Strain Rates

Blasting Induced Rock Fragmentation Prediction Usingthe RHT Constitutive Model for Brittle Materials

Damage to Rocks and Cementitous Materials from SolidImpact Erosion (wear) of rock and concrete

Autogenous


39/62

Abrasion(Wear)Crushing

Differential

BreakageR

ate

SizeLarge (


40/62


41/62

General Conclusions:

Increased evidence indicates that blastinghas a significant impact on crushing andgrinding

Blasting affects both the physical and rockmechanics properties

An important component of optimum

fragmentation appears to be micro-fracturingwithin individual fragments


42/62


Aggregates

Introduction


Crushing & Grinding

Dynamic Fracture

Conclusions


43/62

Aggregate Location

Ontario TraprockQuarry

Algoma Steel Co.Moyle Quarry

Port InlandQuarry Cedarville

QuarryPresque Isle StoneBay County RoadCommission Quarry

EDW. C. Levy Company

Rockwood Stone Quarry

France Stone Co.DennistonFarms Quarry

MichiganUSA

OntarioCanadaLake Superior


44/62

Aggregate Type and Specific Gravity

#Source(MDOT ID) Material Type

Orientation toBedding Gab GB GB,SSD

Porosity(%)

1.Algoma Steel

Air-Cooled Blast

Furnace Slag

Porous Region

Dense Region

2.973

2.888

2.09

2.40

2.41

2.57

30

17

2 Algoma Steel Water Quenched BlastFurnace Slag Random 2.942 2.43 2.61 17

3 Levy Co. Water Quenched BlastFurnace Slag Random 2.985 2.42 2.61 19

4 Presque Isle StoneLimestone Random 2.687 2.51 2.58 6

5 Bay CountyLimestone Perpendicular 2.697 2.63 2.68 2

6 Port InlandLimestone Random 2.69 2.68 2.68


45/62

Air-Cooled Slag


46/62

Water-quenched Slag


47/62

Presque Isle Limestone


48/62

Bay County Limestone


49/62

Port Inland Limestone


50/62

Cedarville Dolomite


51/62

Dennison Farms Dolomite


52/62

France Stone Dolomite


53/62

Basalt - Rapid Geologic Cooling(Flood Basalt)


54/62

Diabase - Slower Geologic Cooling(Traprock)


55/62

Dynamic & Static CompressionStrength Results

0 1 2 3 4 5 6 7 8 9 10 11 12 13

Sample Type

0

100

200

300

400

500

600

700

FailureStrength(MPa)

Dry Rock

1.5

2.5

3.5

AggregateBulkDensityB(g/cm

3)

Dynamic

Static

Bulk Density

A

B

CD

E

A' -- Super High Strength

A -- Very High Strength

B -- High Strength

C -- Medium Strength

D -- Low Strength

E -- Very Low Strength

A'

Sla g Lime stone Dolomite Igneous

next geometric progression

Slag

Limestone

Dolomite

Igneous


56/62

Dynamic to Static Strength Ratio, D/S

d

s

Dynamic Strength D

Static Strength S

d sf

d

s

dd(log )

log

Strain Rate Sensitivity Factor,


57/62

Dynamic to Static Strength Ratios

Material Dynamic/Static(Dry) Dynamic/Static(Saturated)Slag 1.93 2.68Limestone 2.30 2.23Dolomite

1.64 1.83Igneous 1.78 2.55


58/62

Strain Rate Sensitivity ValuesIDNumber

Strain Rate Sensitivity, Aggregate Average

1.0 Algoma air cooled blast furnace slag

porous section 3.00

4.2

1.2 Algoma air-cooled blast furnace slag dense section 9.81

2 Algoma water-quenched blast furnace slag 2.93

3 Levy water-quenched blast furnace slag 1.27

4 Limestone, Presque Isle 9.975 Limestone, Bay County 13.59 16.46 Limestone, Port Inland 25.52

7 Dolomite, Cedarville 10.27

8.6

8 Dolomite, Denniston

8.779 Dolomite, Rockwood 4.52

10 Dolomite, France Stone 10.81

11 Basalt, Portage Lake Lava Series, Moyle 26.90

29.112 Diabase, Ontario Traprock 31.30


59/62

Aggregate Dynamic & StaticStrength Conclusions

D/S: Ranged from 1.3 to 2.7 Slag and igneous had similar D/S and were affected by saturation

Carbonates: limestone had a significantly higher D/S than dolomite

while neither were affected by saturation

Strain Rate Sensitivity Parameter, : Igneous: = 29.1

Limestone: = 16.4

Dolomite: = 8.6

Slag: = 4.2

Variations in appear to be due to the aggregate's microstructure,e.g., Limestone primary precipitate

Dolomite secondary replacement

Eff t f Bl ti th


60/62


Aggregates

Introduction


Crushing & Grinding

Dynamic Fracture

Conclusions/Thoughts


61/62

Conclusions/Thoughts

Aggregate materials are rate sensitive

The D/S ratio appears to indicates the typeof crystalline structure

The rate sensitivity parameter appears tocorrelate with microstructure

Dynamic fracture testing may provide a

means to test micro-structure to betterunderstand friction and other properties


62/62

effects of blasting and the engineering properties of aggregates

Documents