Sand Properties. understanding common tests. School of Civil and Environmental Engineering Particulate Media Research Laboratory

Transcription

1 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

2 Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties

3 Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties

4 Sieve Analysis

5 Computing Particle Size Distribution Percent passing [%] % Sieve opening [mm] 0.01 D 10

6 Important Particle Size Parameters Percent passing [%] Sieve opening [mm] Gap Graded Well Graded Poorly Graded 0.01 Coefficient of curvature Cc = Cu = ( D D D D D ) Uniformity coefficient

7 Size Distribution Packing Density porosity, n D/d=2 D/d= % volume fraction of small particles Guyon et al. (1987)

8 Caution: Capillarity BBC News In pictures Visions of Science

9 Capillarity Holds!

10 Caution: Electrical Forces

11 Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties

12 mm μm μm mm (The Diatoms 1990) Ottawa sand kaolinite diatom table salt crushed granite marl diatom lentil sintered lead precipitated carbonate foraminiferan rice

13 Why Shape? Formation History

14 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

15 Test Loading Configurations 4-point load Brazilian point load long load compression

16 Fines Generation Fines Produced (%) Loaded Area (%)

17 Shape: Cubicity 1 cubic short / intermediate rod-like point load flaky compression long load and Brazilian intermediate / long

18 Crushing Mode: Shape and Fines point load fines 4-point load cubicity compression fines fines cubicity cubicity

19 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

20 Particle Shape: See & Match sphericity roundness (Krumbein and Sloss, 1963)

21 Crater on Mars (April 21, 2004 ) red on left NASA/JPL

22 "Berries" on Mars (February 12, 2004) red on left NASA/JPL

23 Core Martian Rock (August 18, 2004) red on left NASA/JPL

24 Rice red on right

25 Table Salt

26 Ottawa Sand

27 Ottawa Sand

28 Crushed Carbonate

29 Mica

30 Threaded Rubber red on right

31 Particle size Particle shape / crushing e min e max Friction angle Flow test Strength P-wave velocity Thermal properties

32 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

33 e max ρ d min = M V S e max ρwgs = 1 ρ d min

34 e min ρ d max = M V S e min ρwgs = 1 ρ d max

35 Size and Shape Packing Density 1.2 minimum e min maximum e max coefficient of uniformity, C u (Youd, 1973)

36 Mica: bridging & ordering ordering ordering ordering bridging bridging

37 Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties

38 Slope Stability Geotechnical Engineering Photo Album

39 Slope Stability Geotechnical Engineering Photo Album

40 Friction Angle in Sands: Simple!

41 Measure the Angle of Repose

42 Why Friction Angle? rotational frustration? 50 CS friction angle φ cv = R Roundness R

43 Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties

44 Flow Test: Devices

45 Flow Test: Procedure

46 Flow Test: Evolution and Analysis 25 F D D 0 = 0 D 100[%]

47 "Wetness" Crushed granite type III FA/c w/c

48 "Wetness" GDOT standard natural sand FA/c w/c

49 Increase Flow? Add More Paste 200. GDOT Crushed granite sand I 150 Flow [%] too dry V P /V VFA

50 How Much Paste? V Paste / V VFA V Paste / V VFA < 1.0 V Paste / V VFA ~ 1.0 V Paste / V VFA > G controlled by e P C max = VVFA emax ( FA ) V G FA + W C C

51 Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties

52 Strength Compression Loading

53 Before and After Crushing

54 Strength: Add Paste but not too much! 6000 GDOT Standard Sand 6000 Crushed Granite Sand II Strength (psi) too much Strength (psi) too much V P /V VFA V P /V VFA

55 Strength and Flow dry wet flow + correlation strength V Paste / V VFA

56 Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties

57 P-wave velocity

58 P-wave Signals

59 P-wave Velocity vs. Compressive Strength 5000 Strong positive correlation between P-wave and strength 4000 P-wave velocity [m/s] 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

60 Particle size Particle shape / crushing e min, e max Friction angle Flow test Strength P-wave velocity Thermal properties

61 Cities = Thermal Islands

62 Baton Rouge, Louisiana science.nasa.gov

63 Sacramento, California science.nasa.gov

64 Salt lake City, Utah science.nasa.gov

65 Thermal Conductivity: Determination DC Power supply Amp-meter Volt-meter Thermocouple Heating wire

66 Thermal Conductivity: Dry Soils k [W m -1 K -1 ] Ottawa 20/30 sand F110 sand Blasting sand Δk/Δn = Δk/Δn = Δk/Δn = n min n max n min n max n min n max Porosity, n Porosity, n Porosity, n k [W m -1 K -1 ] Crushed sand-i Crushed sand-ii Crushed sand-iii Δk/Δn = Δk/Δn = Δk/Δn = n max n max n max Porosity, n Porosity, n Porosity, n

67 Thermal conductivity: Dry vs. Wet Soils 10 quartz 8.4 Thermal conductivity [W/m.K] 1 ice 2.21 water 0.72 saturated dry Effective vertical stress [kpa]

68 closing thoughts

69 Georgia Tech Research Team

70 Thank You