Geomaterial Characterization Sub-topics • Need for Geomaterial characterization • Geotechnical • Micro-biological (Bio-geo Interface) • Mineralogy • Morphology • Physical • Chemical Pore-solution sampling Corrosion potential Sorption-Desorption • Thermal • Electrical • Magnetic • Radiological
MINERALOGICAL CHARACTERIZATION • X-Ray Diffraction (XRD) • Scanning Electron Microscope (SEM)
SEM micrographs of Silica Fumes & Ground Granulated Blast Furnace Slag (GGBFS/BFS) SF BFS
Determination of fabric structure of fine-grained soils Using SEM Compacted sample Cubic specimen Specimen preparation (Challenges): • Removal of pore fluid from the specimen without disturbing its microstructure. • Freeze-drying technique (for swelling/shrinking type of soils) • Air-drying technique (for non swelling/shrinking type of soils) • Specimen should be able to withstand the vacuum inside the microscope. • As illumination is with electrons, specimen should be made to conduct electricity. • Specimen are coated with a very thin layer of Gold or Carbon (a sputter coater). • Gold coating film can absorb X-ray signal generated into the specimen. • For obtaining X-ray spectrum of a non-conducting sample a coating material very transparent to the X-ray (Carbon) must be utilized.
Mercury Intrusion Porosimetry (MIP) Geomaterials are composed of wide range of particle sizes and shapes and are porous in nature. A knowledge of pore structure of these materials is important as it can give insight in to both the microstructure and the performance. Rather than measuring the porosity, It becomes more informative if the manner in which volume is distributed With respect to pore size. Inter-connected Closed Passing Dead end
Morphological characterization Confocal micrographs (2-Dimensional) SS1 SS3 CS3 Optical micrographs (3 D) SS1 Glass beads SS2 & SS3
r max in r min-cir S Sphericity, S , r min cir r i N r i i 1 N Roundness, R , R r max in r i r max-in =( R + S )/2 Regularity, , R Sample S 0.715 SS1 0.82 0.61 0.675 SS2 0.76 0.60 0.625 SS3 0.75 0.49 CS1 1.0 0.94 0.89 1.0 0.96 CS2 0.92 1.0 0.95 CS3 0.90
PHYSICAL CHARACTERIZATION Image Analysis System
Gradational analysis 100 100 OLA ALA6 80 80 60 60 % finer 40 40 20 20 0 0 1E-3 1E-3 0.01 0.01 0.1 0.1 1 1 10 10 Particle size (mm) Ultra-sieves
Soft Imaging (Laser Particle Scanning) 5000 4500 4000 SF 3500 3000 2500 2000 1500 Number of particles 1000 500 0 1600 1400 FA 3 1200 1000 BFS 800 600 400 200 0 1400 1200 FA 1 1000 FA 2 800 600 400 200 0 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 Particle size ( m)
Property FA 1 FA 2 FA 3 GGBFS SF G 2.03 2.3 2.38 2.84 2.1 Specific surface area 2988 3602 5048 4073 200000 (cm 2 /g) Sand size (>4.75 mm) % 0 0 0 0 ** Silt size (0.002-0.075 mm) % 100 95 90 97 ** Clay size (<0.002 mm) % 0 5 10 3 ** ** Not applicable Number of particles Percentage of particles Particle size FA-1 FA-2 FA-3 GGBFS SF FA-1 FA-2 FA-3 GGBFS SF Range ( m) 0.0-3.0 944 1295 1410 789 4451 47.6 53.0 53.1 40.3 90.6 3.0-6.0 709 989 1061 816 343 35.8 40.5 39.9 41.7 7.0 6.0-9.0 228 116 148 247 48 11.5 4.8 5.6 12.6 1.0 9.0-12.0 57 17 21 59 33 2.9 0.7 0.8 3.0 0.7 12.0-15.0 24 11 4 16 17 1.2 0.5 0.2 0.8 0.3 15.0-18.0 6 2 2 9 6 0.3 0.1 0.1 0.5 0.1 18.0-21.0 4 1 1 5 2 0.2 0 0 0.3 0.0 21.0-24.0 2 0 0 5 3 0.1 0 0 0.3 0.1 24.0-27.0 1 1 0 2 3 0.1 0 0 0.1 0.1 27.0-30.0 2 1 1 5 2 0.1 0 0 0.3 0.0 30.0-33.0 2 6 3 3 4 0.1 0.2 0.1 0.2 0.1 33.0-36.0 2 1 2 3 2 0.1 0 0.1 0.2 0 36.0-39.0 1 0 0 0 0 0.1 0 0 0 0
Specific Surface Area Determination BET nitrogen adsorption Absorption of Ethylene Glycol Monoethyle Ether (EGME) method Methylene blue (MB) dye method Mercury Intrusion Porosimetry (MIP) He gas pycnometer Blaine’s apparatus
MIP He gas pycnometer
Blaine’s Air Permeability Apparatus (ASTM C 204) Portland cement as a standard reference material Specific-surface area (S B ) 3 S (1 e ) e T S s S B 3 e T (1 e) s s S s is the SSA of cement (= 0.346 m 2 /g) e is the void ratio of the sample e s is the void ratio of cement (= 0.5) T s is the time of manometer drop for cement (= 77.18 s) T is the time of manometer drop for the sample
Thermo Gravimetric Analysis
0 TGA Exo. 20 Weight loss (%) Temp. difference ( T) (Dry air atmosphere) 40 DTA 60 Endo. 80 OLA ALA6 TGA and DTA curve 100 for OLA and ALA6 0 samples 20 40 60 (Inert atmosphere) 80 100 800 400 600 200
0 -3.0 FA-3 0 C) -3.2 DSC TGA Temperature difference( , FA-3 20 -3.4 Weight loss (%) -3.6 Heat flow (mW) 40 -3.8 Exo. -4.0 60 -4.2 DTA -4.4 Endo. 80 -4.6 -4.8 100 -5.0 0 200 400 600 800 0 100 200 300 400 500 600 0 C) Temperature ( 0 C) Temperature (
CHEMICAL CHARACTERIZATION • X-Ray Fluorescence (XRF) • Inductively Coupled Plasma (ICP) • pH value • Cation Exchange Capacity (CEC) • Pore solution analysis
XRF Pallets
Inductively Coupled Plasma Unit AAS
Calibration of XRF- Setup XRF Studies Physical Calibartion Chemical Calibration Elemental Composition (% by weight) of Materials Material Element CS WC IC RSS BSS FA-I FA-II C-I C-II GGBFS Si 15.78 20.32 11.52 39.21 40.71 25.53 28.30 24.65 23.62 15.56 Al 5.75 17.77 1.67 2.65 3.29 15.95 15.92 20.70 21.92 8.59 Fe 8.23 1.09 1.19 0.50 0.94 2.51 2.31 1.38 1.81 0.25 Ti 1.53 2.88 0.03 0.22 0.14 2.12 1.45 1.15 1.02 0.37 S - - 0.1 - - 0.01 0.23 0.11 0.03 0.39 Ca 4.58 0.27 38.9 001 0.01 3.20 0.11 0.06 0.10 26.50 K 0.54 0.06 0.13 2.42 1.49 0.77 0.55 1.07 1.14 0.19 Mg 0.99 0.45 0.48 0.09 0.19 0.33 0.24 0.41 0.24 5.52 P 0.07 0.02 5.0 0.01 0.02 0.18 0.25 0.12 0.06 0.02 Sr 0.02 0.00 0.14 - - 0.06 0.07 0.08 0.05 0.08 Ba - - - - - 0.66 0.07 0.11 0.12 0.06 Na 1.49 0.13 - 0.04 - 0.09 0.04 0.08 0.02 0.05 Mn 0.12 0.04 0.01 - 0.04 0.03 0.01 0.01 0.01 0.01 Si +Al+Fe 29.76 39.18 14.39 42.35 44.94 43.98 46.54 46.74 47.35 24.41
variation of pH of the sample 8.0 7.8 7.6 L/S pH 5 10 20 7.4 30 40 7.2 7.0 0 5 10 15 20 25 30 Time (days)
Cation-exchange Capacity Material CEC(meq./100g) 2 Concentrat ion of Ca ( g/ml) 100 Vol. of extract (ml) CEC CS 18.6 Equivalent weight of the cation 1000 wt. of sample (g) WC 5.0 IC 12.6 RSS 3.5 IS:2720 BSS 3.4 FA-I 4.5 FA-II 5.2 C-I 3.9 C-II 4.1 GGBFS Not applicable
Micro-biological Characterization (Bio-geo interface)
IIT Bombay Environmental Geomechanics 28 Lecture No. 5 D N Singh
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