Georgia Construction Aggregate Association Workshop 2008 Sand Properties understanding common tests Douglas Cortes Carlos Santamarina School of Civil and Environmental Engineering Particulate Media Research Laboratory
Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties
Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties
Sieve Analysis
Computing Particle Size Distribution 100 80 Percent passing [%] 60 40 10% 20 0 10 1 0.1 Sieve opening [mm] 0.01 D 10
Important Particle Size Parameters Percent passing [%] 100 80 60 40 20 0 10 1 0.1 Sieve opening [mm] Gap Graded Well Graded Poorly Graded 0.01 Coefficient of curvature Cc = Cu = ( D D D D D 10 60 10 ) 2 30 60 Uniformity coefficient
Size Distribution Packing Density porosity, n 0.36 0.32 0.28 0.24 D/d=2 D/d=10 0 20 40 60 80 100% volume fraction of small particles Guyon et al. (1987)
Caution: Capillarity BBC News In pictures Visions of Science
Capillarity Holds!
Caution: Electrical Forces www.phys.virginia.edu
Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties
mm μm μm mm (The Diatoms 1990) Ottawa sand kaolinite diatom table salt crushed granite marl diatom lentil sintered lead precipitated carbonate foraminiferan rice
Why Shape? Formation History
Crushers: Fines and Shape GDOT Aggregate # 4 material base material # 5 material blasting crusher screen crusher # 6 material crusher screen screen # 7 material # 89 material M10 High Fines Asphalt Sand Gyratory Jaw Cone 3:1 to 10:1 4:1 to 9:1 4:1 to 6:1 sand pool In GA: 2 to 7 In GA: 2 to 8 washed sand < # 200 pond screening
Test Loading Configurations 4-point load Brazilian point load long load compression
Fines Generation Fines Produced (%) 60 50 40 30 20 10 0 0 25 50 75 100 Loaded Area (%)
Shape: Cubicity 1 cubic short / intermediate 0.8 0.6 0.4 0.2 rod-like point load flaky compression long load and Brazilian 0 0 0.2 0.4 0.6 0.8 1 intermediate / long
Crushing Mode: Shape and Fines point load fines 4-point load cubicity compression fines fines cubicity cubicity
Particle Shape - Microphotographs Crushed Granite Sieve 4 Sieve 16 Sieve 50 Sieve 100 Sieve 200 Crushed Limestone Sieve 4 Sieve 16 Sieve 50 Sieve 100 Sieve 200 GDOT Standard Natural Sand Sieve 4 Sieve 16 Sieve 50 Sieve 100 Sieve 200
Particle Shape: See & Match sphericity roundness (Krumbein and Sloss, 1963)
Crater on Mars (April 21, 2004 ) red on left NASA/JPL
"Berries" on Mars (February 12, 2004) red on left NASA/JPL
Core Martian Rock (August 18, 2004) red on left NASA/JPL
Rice red on right
Table Salt
Ottawa Sand
Ottawa Sand
Crushed Carbonate
Mica
Threaded Rubber red on right
Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties
Volumetric Gravimetric Relations ρ = M V e Vv n = = V 1 n s ρ dry M = = V T G ρ s s w 1+ e
e max ρ d min = M V S e max ρwgs = 1 ρ d min
e min ρ d max = M V S e min ρwgs = 1 ρ d max
Size and Shape Packing Density 1.2 minimum e min maximum e max 1.0 0.8 0.6 0.8 0.6 0.4 0.2 1 2 3 4 6 10 coefficient of uniformity, C u (Youd, 1973)
Mica: bridging & ordering ordering ordering ordering bridging bridging
Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties
Slope Stability Geotechnical Engineering Photo Album
Slope Stability Geotechnical Engineering Photo Album
Friction Angle in Sands: Simple!
Measure the Angle of Repose
Why Friction Angle? rotational frustration? 50 CS friction angle 40 30 20 φ cv = 42 17 R 10 0 0.2 0.4 0.6 0.8 1 Roundness R
Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties
Flow Test: Devices
Flow Test: Procedure
Flow Test: Evolution and Analysis 25 F D D 0 = 0 D 100[%]
"Wetness" Crushed granite type III FA/c 2.00 2.75 3.25 4.00 0.42 0.46 0.50 0.54 w/c
"Wetness" GDOT standard natural sand FA/c 2.00 2.75 3.25 4.00 0.42 0.46 0.50 0.54 w/c
Increase Flow? Add More Paste 200. GDOT Crushed granite sand I 150 Flow [%] 100 50 0 too dry 0.5 1.0 1.5 2.0 V P /V VFA
How Much Paste? V Paste / V VFA V Paste / V VFA < 1.0 V Paste / V VFA ~ 1.0 V Paste / V VFA > 1.0 1 G controlled by e P C max = VVFA emax ( FA ) V G FA + W C C
Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties
Strength Compression Loading
Before and After Crushing
Strength: Add Paste but not too much! 6000 GDOT Standard Sand 6000 Crushed Granite Sand II Strength (psi) 4000 2000 too much Strength (psi) 4000 2000 too much 0 0.5 1.0 1.5 2.0 V P /V VFA 0 0.5 1.0 1.5 2.0 V P /V VFA
Strength and Flow dry wet flow + correlation strength V Paste / V VFA
Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties
P-wave velocity
P-wave Signals
P-wave Velocity vs. Compressive Strength 5000 Strong positive correlation between P-wave and strength 4000 P-wave velocity [m/s]. 3000 2000 1000 0 0 1000 2000 3000 4000 5000 6000 Compressive strength [psi] Crushed granite sand type I Crushed granite sand type II Crushed granite sand type III Non-GA natural sand Crushed limestone sand GDOT standard sand Unfailed specimen
Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties
Cities = Thermal Islands http://www.asusmart.com/urbanclimate.php
Baton Rouge, Louisiana science.nasa.gov
Sacramento, California science.nasa.gov
Salt lake City, Utah science.nasa.gov
Thermal Conductivity: Determination DC Power supply Amp-meter Volt-meter Thermocouple Heating wire
Thermal Conductivity: Dry Soils k [W m -1 K -1 ] 0.40 0.35 0.30 0.25 0.40 0.40 Ottawa 20/30 sand F110 sand Blasting sand 0.35 0.35 Δk/Δn =0.908 0.30 Δk/Δn =0.95 0.30 Δk/Δn =0.654 0.25 0.25 n min n max n min n max n min n max 0.20 0.20 0.20 0.30 0.35 0.40 0.45 0.50 0.55 0.30 0.35 0.40 0.45 0.50 0.55 0.30 0.35 0.40 0.45 0.50 0.55 Porosity, n Porosity, n Porosity, n k [W m -1 K -1 ] 0.40 0.35 0.30 0.25 0.40 0.40 Crushed sand-i Crushed sand-ii Crushed sand-iii 0.35 0.35 Δk/Δn =0.935 0.30 Δk/Δn =0.811 0.30 Δk/Δn =1.014 0.25 0.25 0.20 n max 0.30 0.35 0.40 0.45 0.50 0.55 0.20 n max 0.30 0.35 0.40 0.45 0.50 0.55 0.20 n max 0.30 0.35 0.40 0.45 0.50 0.55 Porosity, n Porosity, n Porosity, n
Thermal conductivity: Dry vs. Wet Soils 10 quartz 8.4 Thermal conductivity [W/m.K] 1 ice 2.21 water 0.72 saturated dry 0.1 10 100 1000 10000 Effective vertical stress [kpa]
closing thoughts
Georgia Tech Research Team
Thank You