Particle size and shape characterization distributions measurement techniques
Particle Shape Quantities and Measurement Techniques–A Review
Transcript of Particle Shape Quantities and Measurement Techniques–A Review
- 169 -
Particle Shape Quantities and Measurement Techniques–A Review
Juan M. Rodriguez
Ph.D. Student Department of Civil, Environmental and Natural resources engineering, Luleå
University of Technology, Tel: +46 920 491523, SE – 971 87, Luleå, Sweden e-mail: [email protected]
Tommy Edeskär
Assistant Professor Department of Civil, Environmental and Natural resources engineering, Luleå
University of Technology, Tel: +46 920 493065, SE – 971 87, Luleå, Sweden e-mail: [email protected]
Sven Knutsson
Professor Department of Civil, Environmental and Natural resources engineering, LuleåUniversity of Technology, Tel: +46 920 491332, SE – 971 87, Luleå, Sweden
e-mail: [email protected]
ABSTRACT It has been shown in the early 20th century that particle shape has an influence on geotechnical properties. Even if this is known, there has been only minor progress in explaining the processes behind its performance and has only partly implemented in practical geotechnical analysis. This literature review covers different methods and techniques used to determine the geometrical shape of the particles. Particle shape could be classifying in three categories; sphericity - the overall particle shape and similitude with a sphere, roundness - the description of the particle’s corners and roughness - the surface texture of the particle. The categories are scale dependent and the major scale is to sphericity while the minor belongs to roughness. The overview has shown that there is no agreement on the usage of the descriptors and is not clear which descriptor is the best. One problem has been in a large scale classify shape properties. Image analysis seems according to the review to be a promising tool, it has advantages as low time consumption or repeatability. But the resolution in the processed image needs to be considered since it influences descriptors such as e.g. the perimeter. Shape definitions and its potential role in soil mechanics are discussed.
KEYWORDS: Particle shape, Quantities, Image analysis.
Vol. 18 [2013], Bund. A 170
INTRODUCTION Effects on soil behavior from the constituent grain shape has been suggested since the earliest
1900’s when Wadell (1932), Riley (1941), Pentland (1927) and some other authors developed their own techniques to define the form and roundness of particles. Into the engineering field several research works conclude that particle shape influence technical properties of soil material and unbound aggregates (Santamarina and Cho, 2004; Mora and Kwan, 2000). Among documented properties affected by the particle shape are e.g. void ratio (porosity), internal friction angle, and hydraulic conductivity (permeability) (Rousé et al., 2008; Shinohara et al., 2000; Witt and Brauns, 1983). In geotechnical guidelines particle shape is incorporated in e.g. soil classification (Eurocode 7) and in national guidelines e.g. for evaluation of friction angle (Skredkommisionen, 1995). This classification is based on ocular inspection and quantitative judgment made by the individual practicing engineer, thus, it can result in not repeatable data. The lack of possibility to objectively describe the shape hinders the development of incorporating the effect of particle shape in geotechnical analysis.
The interest of particle shape was raised earlier in the field of geology compared to geotechnical engineering. Particle shape is considered to be the result of different agent’s transport of the rock from its original place to deposits, since the final pebble form is hardly influenced by these agents (rigor of the transport, exfoliation by temperature changes, moisture changes, etc.) in the diverse stages of their history. Furthermore, there are considerations regarding on the particle genesis itself (rock structure, mineralogy, hardness, etc.) (Wentworth 1922a). The combination of transport and mineralogy factors complicates any attempt to correlate length of transport and roundness due that soft rock result in rounded edges more rapidly than hard rock if both are transported equal distances. According to Barton & Kjaernsli (1981), rockfill materials could be classified based on origin into the following (1) quarried rock; (2) talus; (3) moraine; (4) glaci-fluvial deposits; and (5) fluvial deposits. Each of these sources produces a characteristic roundness and surface texture. Pellegrino (1965) conclude that origin of the rock have strong influence determining the shape.
To define the particle form (morphology), in order to classify and compare grains, many measures has been taken in consideration (axis lengths, perimeter, surface area, volume, etc.). Furthermore, corners also could be angular or rounded (roundness), thus, the authors also focus on develop techniques to describe them. Additionally corners can be rough or smooth (surface texture). Nowadays some authors (Mitchell & Soga, 2005; Arasan et al., 2010) are using these three sub-quantities, one and each describing the shape but a different scale (form, roundness, surface texture).
During the historical development of shape descriptors the terminology has been used differently among the published studies; terms as roundness (because the roundness could be apply in the different scales) or sphericity (how the particle approach to the shape of a sphere) were strong (Wadell, 1933; Wenworth, 1933; Teller, 1976; Barrett 1980; Hawkins, 1993), and it was necessary in order to define a common language on the particle shape field; unfortunately still today there is not agreement on the use of this terminology and sometimes it make difficult to understand the meaning of the authors, that’s why it is better to comprehend the author technique in order to misinterpret any word implication.
Several attempts to introduce methodology to measure the particle’s shape had been developed over the years. Manual measurement of the particles form is overwhelming, thus, visual charts were developed early to diminish the measuring time (Krumbein, 1941, Krumbein and Sloss, 1963; Ashenbrenner, 1956; Pye and Pye, 1943). Sieving was introduced to determine
Vol. 18 [2013], Bund. A 171 the flakiness/elongation index but it is confined only for a certain particle size due the practical considerations (Persson, 1988). More recently image analysis on computer base has been applied on sieving research (Andersson, 2010, Mora and Kwan, 2000, Persson, 1998) bringing to the industry new practical methods to determine the particle size with good results (Andersson, 2010). Particle shape with computer assisted methods are of great help reducing dramatically the measuring time (Fernlund, 2005; Kuo and Freeman 1998a; Kuo, et al., 1998b; Bowman, et al., 2001).
In the civil industry e.g. Hot Asphalt mixtures (Kuo and Freeman, 1998a; Pan, et al., 2006), Concrete (Mora et al., 1998; Quiroga and Fowle, 2003) and Ballast (Tutumluer et al., 2006) particle’s shape is of interest due the material’s performance, thus, standards had been developed (e.g. EN 933-4:2000 Tests for geometrical properties of aggregates; ASTM D 2488-90 (1996) Standard practice for description and identification of soils).
Sieving is probably the most used method to determine the particle size distribution. This traditional method, according to Andersson (2010) is time consuming and expensive. Investigations shows that the traditional sieving has deviations when particle shape is involve; the average volume of the particles retained on any sieve varies considerably with the shape (Lees, 1964b), thus, the passing of the particles depend upon the shape of the particles (Fernlund, 1998). In some industries the Image analysis is taking advantage over the traditional sieving technique regardless of the intrinsic error on image analysis due the overlapping or partial hiding of the rock particles (Andersson, 2010). In this case the weight factor is substitute by pixels (Fernlund et al., 2007). Sieving curve using image analysis is not standardized but after good results in the practice (Andersson, 2010) new methodology and soil descriptions could raise including its effects.
Describing the particle’s shape is the main objective, there are 42 different quantities in this document, and it is required to review the information about them to comprehend and interpret the implication of each quantity to determine them usability and practice.
DESCRIPTION OF SHAPE PROPERTIES Particle shape description can be classified as qualitative or quantitative. Qualitative describe
in terms of words the shape of the particle (e.g. elongated, spherical, flaky, etc.); and quantitative that relates the measured dimensions; in the engineering field the quantitative description of the particle is more important due the reproducibility.
Quantitative geometrical measures on particles may be used as basis for qualitative classification. There are few qualitative measures in contrast with several quantitative measures to describe the particle form. Despite the amount of qualitative descriptions none of them had been widely accepted; but there are some standards (e.g., ASTM D5821, EN 933-3 and BS 812) specifying mathematical definitions for industrial purposes.
Shape description of particles is also divided into two: -3D (3 dimensions): it could be obtained from a 3D scan or in a two orthogonal images and -2D (2 dimensions) or particle projection, where the particle outline is drawn.
3D and 2D image analysis present challenges itself. 3D analysis requires a sophisticated equipment to scan the particle surface and create the 3D model or the use of orthogonal images and combine them to represent the 3 dimensions. The orthogonal method could present new challenges as the minimum particle size or the placing in orthogonal way of the particles (Fernlund, 2005). 2D image analysis is easy to perform due the non-sophisticated equipment
V requir2D imintermor ran1941;
Indefiniusing morphdefine
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Vol. 18 [20
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Table 2: Gen
Aspect Sphericity (3D)
The techniqueture some wayarticle project
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r (1956) devedle one.
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Name
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Spheric
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. A
eloped the sha
ew over diffn compiled a
s index phericity onal sphericity
city
s classificationpt sphericity chsphericity
shape factor ng sphericity actor um projection ity
ms shape factororm factor
prolate index
FOthe sphericit
e the “two dimthors named “
ape factor by
ferent particland arranged
Author
WentwoWadell
y Wadell
Wadell
Zingg’s1
hart KrumbePye and Corey2
AshenbrAshenbr
Sneed &r William
Janke2
Dobkins
RM (2D)ty is based inmensions sph“particle outli
using the rela
le shape defid chronologic
orth
1
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renner renner
& Folk ms2
s & Folk 1) K2) B
) n three dime
hericity” whicine” or “circu
ation of the tr
initions for 3cally
Year Base
1922a 3-axe1932 Surfa1932 Volu
1934 Sphediam
1935 3-axe1941 3-axe1943 3-axe1949 3-axe1956 3-axe1956 3-axe
1958 3-axe1965 3-axe1966 3-axe
1970 3-axeKrumbein and SlosBlott and Pye, 2008
ensions, it cach is simply thularity”.
17
(9
(10
(1
ree axis but th
(12
3D sphericity
ed on
es ace ume ere
meter
es es es es es es
es es es
es ss, 1963 8
an be found ihe perimeter o
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2)
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Torientand th
Sown Eequal (P) timorient
Rpropowere handlWade18). Hperim
JaEquatdeviatdetermradial
Vol. 18 [20
Wadell in 193ation 4) to a 2
maximum crotions (13) shomscribed circe perimeter of
Tickell in 193tation proposehe area of sma
ome other auEquations as to longest len
me a constantation of the g
Riley (1941), osed by the ab
not computee called “ins
ell and the relHorton 1932 (
meter of a circl
anoo in 1998tion 20. Sukution of the gmine the iteml divisions).
13], Bund.
35 (Hawkins2D outline. Hss sectional aow the relatiole (DC). He a
f a circle of sa
31 (Hawkins,ed was a randallest circums
uthors has bePentland (192ngth outline (
nt, Equations grains.
realize the pbove authors
er, all was mscribed circlelation of diam(Hawkins, 19le of the same
(Blott and Pumaran and Aglobal particlems used in the
. A
, 1993) adopHe defined anarea (outline on between dlso used the t
ame area (PC)
, 1993) useddom one. It iscribed circle
en working w27) relating th(AC2), and Co16 and 17 re
problems that can carry as
made by hand sphericity”.
meters of insc993) use the re area as drain
Pye, 2008) deAshmawy (200e outline frome Equation 2
pt a conversin orientation o
of the particdiameters of aterm “degree and the actua
d his empirics described b(AC).
with the “cirche area (A) oox (Riley, 194espectively. B
t an area, pes the time con
d), and that’s He used the
cribed (DI) anrelation of thenage basin (P
evelop his ge01) develop hm a circle. F1 (N, referred
ion of his 19on the particlcle projectinga circle of saof circularityal particle per
cal relation (Eby the ratio be
cularity” concoutline and ar41) with the rBoth authors
erimeter and nsuming andwhy he dev
e same particnd circumscre drainage baPCD), see Equa
eneral ratio ofhis own shapFigure 9 can d to the num
934 3D spheles and they g the maximuame area (DA
y” (Equation rimeter (P).
Equation 15)etween the ar
cept and hadrea of a circleratio area (A)did not defin
some other d tedious worvelop this Eqcle orientationribed (DC) cirasing perimeteation 19.
f perimeter (Pe factor (SF) be used as
mber of sampl
17
ericity formuwere based oum area). Th
A) and smalle14) as the rati
). The particrea outline (A
(13
(14
(15
d develop theme with diamete) and perimetene any defini
(16
(17
measuremenrk (at that timquation easy tn proposed brcles (Equatioer (PD) and th
(18)
(19)
P) to area (Adefined as tha reference t
les intervals o
78
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5)
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7)
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)
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Wroundcircleused Eon the
Vol. 18 [20
Figure 9: De
Roundness as e the corners ested many w
Roundness is cguration and erning about t), is describe imposed in th
Wadell (1935)dness of a par diameter (RmEquation 23 (e results (Wad
13], Bund.
escription of (S
ROUdescribed pand how theyays to describ
clearly underdenotes the
the sharpnessas the third o
he corners, an
) describes hirticle using thmax-in), see (N, is the numdell, 1935).
. A
the SukumaSukumaran a
UNDNESSreviously is y are, this wabe this second
standable usisimilarities w
or the smootorder subject nd it is also a p
is methodologhe average raFigure 11 an
mber of corne
aran factors tand Ashmaw
S OR ANGthe second o
as notice by md order particl
ing the Figurewith a spherthness of the (form is the fproperty of pa
gy, calling it adius of the cnd Equation 2ers). This two
to determinewy, 2001).
GULARITorder shape most of the aule property.
e 1. Particle sre (3D) or a perimeter (2D
first and rounarticles surfac
total degree corners (r) in 22. In the sam last Equation
e the shape a
TY descriptor. Suthors sited b
shape or formcircle (2D).
D). Surface tndness the secces between c
or roundnesn relation withme study Wadn shows sligh
17
and angularit
(20
(2
Sphericity lefbefore and the
m is the overaRoundness
texture (Barrecond), and it corners.
s to obtain thh the inscribedell (1935) hahtly difference
79
ty
0)
1)
fts ey
all is
et, is
he ed as es
V
ACi
PIt is idegreof get
Fi
Vol. 18 [20
Table 3:
Aspect ircularity
(2D)
d
owers (1953)important to e of subjectivtting errors is
igure 11: W
13], Bund.
General chr
Name
roundness
roundness
roundness
Circularity
outline circuladegree of circul
inscribed circsphericity
Circularity
Shape facto
) also publishhighlight tha
vity. Folk (19negligible fo
adell’s meth
. A
ronological o for 2
y
arity larity cle
y Kru
or S
ed a graphic at any compa955) concludeor sphericity b
hod to estimacircle (H
(22)
overview of 2D sphericity
Author
Pentland
Cox1
Tickell2
Horton2
Wadell Wadell
Riley
umbein and Sloss
Janoo
ukumaran
scale to illustaring chart toes that when cbut large for ro
ate the roundHawkins, 19
f the particle y.
Year
1927
1927
1931
1932
1935 1935
1941
1963
1998
2001 Seg
1) R2) H
trate the qualio describe parcharts are useoundness.
dness, corner993).
shape defini
Based o
area
area-perim
area
drainage b
Circle diamPerimet
Circle diam
chart
area-perim
gmentation of angles
Riley, 1941 Hawkins, 1993
itative measurticle propert
ed for classific
rs radius and
18
itions
on
meter
basin
meter ter
meter
t
meter
particle and s
ure (Figure 12ties has a higcation, the ris
d inscribed
(23)
80
2). gh sk
)
V
Sclassiis imp(1935
TabG
VeAn
Sub
Sub
Ro
We
Kround
Fa censubtenFigur
T(ANG
Vol. 18 [20
F
ome authors fication basedportant to de
5). This classi
ble 4: Degrerade terms
liery angular ngular 0
bangular 0
brounded 0
ounded 0
ell rounded 0
Krumbein anddness paramet
ischer in 193ntral point in nded by the se 14.
To express thGPLA) on the o
13], Bund.
Figure 12: A
as Russel & Td on five andenote that thefication and c
es of roundnRussell & Tayl
Class imits (R)
Am
N/A 0.00-0.15
0.15-0.30
0.30-0.50
0.50-0.70
0.70-1.00
d Sloss (1963)ters using com
3 (Hawkins, the outline
straight or no
he angularityoutlines and co
. A
A Roundness
Taylor in 193d six classes (e way they mclass limits ar
ness: Wadelllor (1937)
Arithmetic midpoint l
N/A 0.075 0
0.225 0
0.400 0
0.600 0
0.800 0
) published amparison. See
1993) used aand dividing
on-curved par
y value Fischoncave (ANG
s qualitative
37, Pettijohn iHawkins, 199measure the re showed in t
l Values. (HaPettijohn
Class limits (R)
N/A 0.00-0.15
0.15-0.25
0.25-0.40
0.40-0.60
0.60-1.00
a graphical che Figure 13. (C
a straightforwg the outline ts of the prof
her used theGCON) Equatio
scale (Powe
in 1957 and P93) each one roundness isthe Table 4.
awkins, 199n (1957)
Arithmetic midpoint
N/A 0.125
0.200
0.315
0.500
0.800
hart easy to dCho, et al. 20
ward method tin angles ar
file were mea
e ratio of anons 24 and 25
ers, 1953)
Powers in 195with its own
s the develop
3), N/A = noPowers
Class limits (R) 0.12-0.17 0.17-0.25
0.25-0.35
0.35-0.49
0.49-0.70
0.70-1.00
determine the 006).
to quantify roround this pasured. This i
ngles standin5 respectively
18
53 developed class limits;
ped by Wade
o-applicables (1953)
Arithmetic midpoint
0.14 0.21
0.30
0.41
0.59
0.84
sphericity an
oundness usinoint that weris illustrated i
ng linear par.
81
d a it
ell
e
nd
ng re in
rts
V
Figu
Fabove
Wparticdiamein miratio oaxis (
Vol. 18 [20
ure 13: Sphethat
Figure 1
igure 14 left e Equations. (
Wentworth in cle to obtain teter of a circlenimum projeof the radius B), see Equat
13], Bund.
ericity and rappears here
4: Fischer’s A=ins
(A) and righ(Hawkins, 199
1922 (Equatithe outline ore fitting the shection (SM). Wof curvature tion 27.
. A
oundness che in the chart
methods of scribed circl
ht (B), gives 93).
ion 26) used tr contour (Baharpest corneWentworth (Hof the most c
(24)
(26
hart. (Cho et,t is the wade
f angularity ce; B=circum
a similar ang
the maximumarret, 1980). Ter (DS) and theHawkins, 199convex part (R
)
, al., 2006). Tell’s Equatio
computation mscribed circ
gularity of ap
m projection tThe Equatione longest axis
93) also exprRCON) and the
The roundneon number 22
(Hawkins, 1cle
pproximately
to define the n reflects the s (L) plus the ressed the roue longest axis
18
ess Equation2
1993)
0.42 using th
position of threlation of thshortest axis
undness as ths (L) plus sho
(25)
(27)
82
n
he
he he c he ort
V
Apartic
Daxis ba, b an
W1980)the sh
Wthe av
C(EquacorneWentwEquat
Swcornehis Aperim
Langul
Vol. 18 [20
Actually thesecle is in its ma
Dimensions cab. The intentiond c are for 3
F
Wentworth 19) and it relateharpest corner
Wentworth (19verage radius
Cailleux (Barration 31). Kur (DS) and tworth roundntion 33.
wan in 1974 r(s) (DS1 and
Average roundmeter (PCON) an
Lees (1964a) darity instead
13], Bund.
e last two Equaximum proje
an be seen onon is to make D).
Figure 15: D
919 has a seces the diameter (DX).
922b), used dof the pebble
rett, 1980) reuenen in 1956the breath axness with the
shows his EqDS2) and ins
dness of outlnd the actual
developed anof the round
(31
. A
(
uations are thection.
n Figure 15, Ldifference be
Description o
cond way to er of the shar
define the roue (RAVG):
elates the rad6 show his roxis (B), Equarelation of sh
quation (Barrcribed circle line (Krumbeperimeter (P)
n opposite dedness, and he
(29)
)
(34)
he same, just
L and B repreetween the 2
of L and B a
express the rpest corner (D
undness as the
dius of the moundness indeation 32. Doharpest corner
rett, 1980) rediameter (DI
ein and Petti), Equation 35
finition to roe calls it Deg
t expressed in
esents the maand 3 dimens
axes (Hawkin
roundness caDS) and the d
e ratio of the
most convex ex (Barrett, 1
obkins & Folr (DS) and ins
lating the shaI), Equation 3ijohn, 1938) 5.
oundness, it mgree of angul
(32)
n different te
ayor axis a ansions (L and B
ns, 1993)
alled Shape idiameter of a
sharpest corn
part and th1980) betweelk (1970) usescribed circle
arpest (or the34. Szadeczsk
relating the
means that helarity. Figure
18
(35)
erms, when th
nd intermediaB are for 2D a
index (Barreta pebble troug
ner (RCON) an
he longest axen the sharpeed a modifie diameter (DI
e two sharpesky-Kardoss ha
concave par
e measures th 16 shows th
(28)
(30)
(33)
83
he
te as
tt, gh
nd
xis est ed I),
st) as rts
he he
V requirthe di
Inindivi
A(1998
Tthe deEquatbut it
Vol. 18 [20
rements consiistance (x). Se
n order to apidual result w
Figure 16
A roundness i8b) it is descri
The last Equatefinition furthtion that has bis a good exa
13], Bund.
idered when Eee Equation 3
pply the Equwill add to eac
6: Degree of
index appearibed as:
tion appears ahermore sombeen used tryiample of the m
. A
Equation 36 a36.
uation 36 corh other to obt
f angularity m
rs on Janoo (
also as a 2D dme authors ha
ing to define misuse of the
applies as the
rners needs ttain the final
measuremen
(1998), Kuo
descriptor becad used to dedifferent aspequantities an
e angles (α), i
to be entereddegree of ang
nt technique
and Freeman
cause there is efine the rougects (spherici
nd definitions.
inscribed circ
d in the formgularity.
(Blot and P
n (1998a) an
not a generalghness, this iity, roundness.
18
cle (Rmax-in) an
mula, and eac
(36
ye, 2008)
nd Kuo, et, a
l agreement ois not the onls or roughnes
(
(17)
84
nd
ch
6)
al.
on ly s)
V
Sunumbshown
Subecaube use
Asp
Round
Vol. 18 [20
Table
ukumaran anber of sharpnen in Figure 9:
ukumaran anuse it is the cued to describe
pect
dness shape in
shape in
roundne
Averagoutline
roundne
roundne
roundne
roundne
roundne
roundne
roundne
degree
Angula
13], Bund.
e 5: General
nd Ashmawyess corners (E:
nd Ashmawyut off betweene the roughne
Name
ndex
ndex
ess
e roundness of
ess
ess
ess
ess
ess
ess
ess
of angularity
rity factor
. A
chronologic
y (2001) presEquation 37).
y (2001) also n angularity fass.
A
Wentwort
Wentwort
Wentwort
Fischer
Fischer
Szadeczsk
Wadell
Wadell
Russel &
Krumbein
Cailleux
Pettijohn
Powers
Kuenen
Krumbein
Lees
Dobkins &
Swan
SukumaraAshmawy
cal overview
sent an anguAngles βi req
suggested usfactor and surf
Author
th
th
th
ky-Kardoss
Taylor
n
n and Sloss
& Folk
an and y
w of the parti
1) B2) H3) K4) P
ularity factor quired to obta
se not bigger face roughnes
Year
19191 diam
1922b shar
1933 conv
19332 nonc
19332 nonc
19333 conv
1935 diam
1935 diam
19372 clas
1941 char
19471 conv
19494 clas
1953 char
19561 axis
1963 char
1964a corncircl
1970 diam
19741 diam
2001 Segmangl
icle roundne
Barret, 1980 Hawkins, 1993 Krumbein and PettiPowers, 1953
(AF) calculain the angula
sampling intss. If so this E
Based on
meter of sharper
rpest corner and
vex parts
curved parts out
curved-straight p
vex parts-perime
meter of corners
meter of corners
s limit table
rt
vex parts
s limit table
rt and class limit
s-convex corner
rt ners angles and ile
meter of sharper
meter of sharper
mentation of parles
18
ss
ijohn, 1938
lated from tharity factor ar
terval of N=4Equation coul
n
corner
axis
tline
parts outline
eter
t table
inscribed
corner
corners
rticles and
(37)
85
he re
40 ld
V
Aroundwith t
WaggresynthtimesThe leThe d
Fig
Hhere i
Odefine
Tbetwe
Vol. 18 [20
A third propedness propertithe authors, at
Wright in 195gate using stetic resin. Th. The unevenength was the
difference betw
ure 17: Mea
However, withis presented so
One techniqueed as the ratio
The convex peen the touchi
Figu
13], Bund.
ROUGHerty called ties, since thent that time, no
5 developed tudies done ohe stones wernness of the sen compared ween these tw
asurement m
h the advanceome research
e used by Janoo between per
perimeter is oing points tha
ure 18: (a) C
. A
HNESS ORexture appean, texture proot measurable
a method to qon 19 mm stre cut in thin urface was trwith an unev
wo lines was d
method for ch(Ja
e of technoloher’s ideas how
oo (1988) to drimeter (P) an
obtained usinat the Feret’s b
Convex perim(modified
R SURFAars early in operty was lone.
quantify the stones. The tesections. The
raced and theven line drawdefined as the
haracterizinganoo, 1998)
ogy it has becw this propert
define the round convex per
ng the Feret’box describes
meter (CPER)after Janoo,
ACE TEXTthe literaturnged describe
surface texturst aggregatese sections proe total length wn as a seriese roughness fa
g the surface
come easier mty should be c
ughness can brimeter (CPER)
’s box (or ds each time it
), (b) Feret m, 1998)
TURE e with the sed but it was
re or roughnes were first eojection was of the trace w
s of chords (sfactor. (Janoo
e texture of a
measure the calculated.
be seen in Fig).
diameter) tendis turn (Figur
measurement
18
sphericity an in accordanc
ess of concretembedded in magnified 12was measuredsee Figure 171998).
an aggregate
roughness an
gure 18a and
ding a line ire 18b).
t
(38)
86
nd ce
te a
25 d.
7).
nd
is
in
V
Kratio p
EErosiosurfacthe redimencycleserosio
Mratio, invest
TThis iperimconve
Haccuraworks
Vol. 18 [20
Kuo and Freemperimeter (P)
Erosion and don is a morphce, which leaeverse processnsion by addis are not stanon-dilatation (
Mora and CR” (Equati
tigation, they
Figur
The convex aris illustrated
meter but in thex area
TECHN
Hand measureacy special ds placing the
13], Bund.
man (1998a) and average
dilatation imahological procaves the objecs of erosion ang pixels arou
ndardized. A (Equation 40)
ion 41) and tare:
re 19: Evalu
rea is the areain the Figure
his case the a
NIQUES
ment techniqdevices develsample on th
. A
and Kuo et adiameter (DA
age processincess by whichct less dense and a single dund its boundrepresents the).
Kwan the “fullness
ation of area
a of the minie 19. The conarea between
S TO DE
HAND Mque was the filoped as the he sliding roa
(39)
(41)
al., (1998b) uAVG), Equation
g techniques h boundary imalong the pe
dilatation cycdary (Pan et ae original are
(2000) uratio, FR” (E
a and convex
mum convexnvex area is othe original
ETERMIN
MEASUREirst used by o“sliding rod
ad calliper as
)
)
use the roughn 39.
are used to mage pixels a
erimeter or oucle increases al., 2006). Thea and A1 is
used the Equation 42)
x area (Mora
x boundaries cobtained in a outline and t
NE PART
EMENT obvious reasod caliper” use
show Figure
hness (RO) de
obtain the suare removed uter boundarythe particle s
he “n” erosionthe area after
“conin
a and Kuan,
circumscribina similar way the convex pe
TICLE S
ons, in order ted by Krumbe 20b the leng
18
efinition as th
urface texturfrom an objey. Dilatation shape or imagn and dilatatior “n” cycles o
nvexity the
2000)
ng the particlas the conve
erimeter is ou
SHAPE
to improve thbein (1941), gth in differen
(40)
(42)
87
he
re. ct is
ge on of
eir
le. ex ur
he it nt
V positiactualshape20a shcurvarock fshow
F(W
(Kru
Athe papartic
Fi
Spropeand eaggrevalue
Vol. 18 [20
ons can be oblly used by op
e analysis (Wehows (the tw
ature; or the “fragment, so, equipment.
Figure 20: (aWenworth, 19
umbein, 194
Another helpfuarticle’s contocle’s diameter
igure 21: Ci
ieving, e.g. aerties. By comelongation indgate particlessuch as 5:1.
13], Bund.
btain by usinpticians to mentworth, 192
wo adjacent pi“Szadeczky-K
the outline tr
a) convexity922b), (b) sli41) and c) Sz
ul tool to deteour over a cirr.
ircle scale us
according to mbining meshdex, ASTM Ds that have aThe index re
. A
ng the scale prmeasure the cu22b) works mivots are inva
Kardoss’s appraced is then
y gage, used iding rod calzadeczky-Ka
the pa
ermine the parcle scale app
sed by Wader
SIEVEEN 933-3:1
h geometries tD4791 (Flat
a ratio of lengepresents the p
rovided in thurvature of len
measuring the ariable) as maparatus” devel
analyzed (Kr
to determineliper, deviceardoss (1933article outlin
article dimensearing in Figu
ell (1935) to oundness
E ANALYS1997, can bethe obtained rand elongate
gth to thicknpercentage on
he handle; thenses but easimovement ofany the centrlop in 1933 trumbein and P
e the curvatue to measure 3) apparatus,ne.
sions was thegure 21, thus i
determine p
SIS e used to detresults can beed particles a
ness equal to n weight of th
e “convexity gly applicable f the central pral pivot movthat traces thePettijohn, 193
ure in particlthe particle it was utiliz
e “camera lucit is possible
particle’s dia
termine simpe used to quaare defined aor greater th
hese particles
18
gage” that wa to the particpivot as Figurves more is the profile of th38) Figure 20
le corners axis length
zed to obtain
cida” to projeto measure th
ameter and
ple large scaantify flakinesas those coarshan a specifies). The metho
88
as le re he he 0c
n
ct he
le ss se ed od
V is notthe sieEN 9from fractiothe pafoundstandausing compKwanthe teis theadvan
Crequirfor pdifficu
Acharacroundchart
Atwo mthat edefini
Fdetermthat thhe conhis stu
Vol. 18 [20
t suitable for eve, and the g33-3:1997 re4 mm and uon and the searticles is ob
d, finally witards related wsieve analys
uters age andn, 2000; Perssesting time coe error due thntages are mo
Charts develored when meebbles whichult to measur
Fig
A qualitative ccteristics, it w
ded, rounded was prepared
A new chart inmean propertieliminated thitions. (Krum
olk (1955) wmination of sphe sphericity ncluded, it waudy.
13], Bund.
fine materialgreat amount lated to flaki
up to 63 mm. econd use a bbtain and witth this two pwith the partisis to determid image analyson, 1998). Inompare with the overlappinre compare w
ped over theasuring each h were mease due to the s
gure 21: Kru
chart by Powewas divided oand well rou
d with photogr
ncluding spheies of particlhe subjectivit
mbein and Slos
worried abouphericity anddeterminatioas necessary t
. A
ls. This due tof particles i
iness index. two sieving
bar sieve, afteth the secondparameters thicle shape butine particle’sysis sieving rndustry is alsothe traditionang or hiding
with disadvant
CHART Ce necessity oparticle. Kru
sured by Waecond order s
umbein (194
ers (1953) tryon six roundnunded) and twraphs to enha
ericity and roe’s shape, futy of qualitass, 1963). (Se
ut the persoangularity (h
n by chart coto carry out a
to the difficuln relation to tThe test is poperations a
er the first sied sieving (bahe flakiness t, this above geometrical
research is tako applying thl sieving metof the partic
tages (Anders
COMPARof faster resuumbein (1941adell’s methoscale that roun
41) comparis
y to include bness ranges (vwo sphericityance the reade
oundness appeurthermore, thative descriptee Figure 13).
on’s error onhe used the Poomparison hasa more wide r
lty to get the the area of th
performed on are necessary,eving the avear sieving) th
index is depresented areproperties. S
king place (Ae image analythod. An incocles during thson, 2010).
RISON ults because 1) present a cod because thndness repres
son chart for
both (sphericitvery angular,y series (higher perspective
ear, this timehere was incltion. The ch
n the chart’owers 1953 cs a negligibleresearch due t
fine grains phe sieve (Persn aggregates w, the first sep
erage maximuhe shortest axetermined. The probably thSieve analysiAndersson, 20ysis sieving wonvenient of ithe capture p
the long timcomparison rohis property sents. (See Fi
r roundness
ty and roundn, angular, subh and low spe. (See Figure
e it was easierluded the numhart is based
s comparisocomparison che error while the high varia
18
passed througson, 1998) e.with grain sizparates on sizum diameter oxis diameter here are morhe most knows is facing th010; Mora anwith decrees oimage analys
process but th
me consuminoundness chawas the mogure 22).
ness) particleb-angular, subphericity). The 12)
r to handle thmerical value
d on Wadell
on studied thhart), he founthe roundnes
ability show b
89
gh g. ze ze of is re
wn he nd on sis he
ng art ost
’s b-
his
he es ’s
he nd ss, by
V
Imautom
-
-
-
Fth
Vol. 18 [20
mage analysismated. Differe
Feret Diamcan rotate 22 (left) tto determin
Fourier Teindividual textural feentrant ang(right).
Fractal Dimand Vallejof the fract
Figure 22: (lehe particle to
te
13], Bund.
s is a practicaent techniques
meter: the Feraround one phese method ne diameters
echnique: It particles (Eq
eatures for grgles in order
mension: Irreo, 1997), Figtal line can be
eft) Feret meadefine the shoechnique with
. A
IMAGEal method to us appear to pr
ret diameter iparticle, or ouis not a fine (Janoo, 1988
produces maquation 43). anular soils. to complete
egular line at gure 23 showse defined as E
asurement techortest and lonh two radiuses
E ANALYSuse for shaperocess these im
is the longituutline, to defidescriptor, bu)
athematical reThis methodThe problemthe revolutio
any level of s fractal analyEquation 44.
hnique is defingest Feret dias at one angle
YSIS e classificatiomages, among
ude between tfine dimensionut as it was s
elations that d favours the m in the methon (Bowman
f scrutiny is bysis by the d
ined by two pameter (Janooe (Bowman et
n since it is fg them are:
two parallel lns, as it is shay above it is
characterize analysis of
hodology remet al., 2001),
by definition dividing meth
parallel lines to, 1988), (right al., 2001)
19
fast and can b
lines, this linehown in Figurs a helpful too
the profile oroughness an
mains in the re see Figure 2
fractal (Hysliod. The lengt
turning arounht) Fourier
(43)
(44)
90
be
es re ol
of nd e-22
ip th
nd
V
-
-
-
Lcan se
Adigitaanalyparticresolu
Wbetter
Vol. 18 [20
Figure 2
Orthogonabetween thtechniques
Laser Scantechniquesparticles hthe lower Tolppanen
Laser-Aidesurveying as to use lcertain per
Figure 2
Last two 3D teee in Figure 2
All these preval way obtainisis regarding
cles; orientatioution have an
When resolutir with the real
13], Bund.
23: Fractal an
al image analyhem to acquirs can be used
nning Technis. In Figures have control p
part, in Fign, 2002).
ed Tomograp(see Figure 2iquid with sarcent of light
4: a) Scanni
echniques obt25 (right).
vious techniqing the desireon the errors
on is not releinfluence on
ion is increasl form, in the
. A
nalysis by th(Hyslip a
ysis: This tecre the three pain this orthog
ique: this kin24a) is show
points in ordegure 24b) it
phy (LAT), in25, left)). Thiame refractivego through. (M
ing head, b)
tain the partic
ques are easiled measuremes involve, amvant when it the accuracy
se more accuother hand, m
he dividing mnd Vallejo,
chnique is basarticle dimensgonal way.
nd of laser scwed the laserer to keep a r
can be see
n this case a lis technique ie index as theMatsushima e
scanning pat
cle shape that
ly written in ent, but there
mong them areis random an. (Zeidan et a
uracy is obtamore resolutio
method at dif1997)
sically the usesions (Fernlu
canning 3D isr head scann
reference pointhe laser pa
laser sheet is is different ane particles, paet al., 2003).
th (Lanaro a
t is later used
codes or scrare some inte
e image resolnd large numbal., 2007)
ain and the oon means mor
fferent scrut
e of two imagund, 2005), an
s one of the mning the rocknt when moveath followed
used to obtaind has speciaarticles must
and Tolppane
d to achieve m
ripts to be ineresting pointlution and oriber of particl
object represere spending o
19
tiny scale
ges orthogonny of the abov
most advancek particles, the them to sca. (Lanaro an
in the particleal requiremenlet the laser o
en, 2002)
measures as w
nterpreted in ts in the imagientation of thes are involv
entation matcon memory an
91
al ve
ed he an nd
es nts or
we
a ge he e;
ch nd
V time; (Schä
Srelativbut nsimilaoutpuperim
IndefiniKrumused Arasadifferthree singledescriliteratis notroundProbato rec
Manalyagreemother
T(3-dim
Vol. 18 [20
thus, resolutäfer, 2002).
Figure 25: c
chäfer (2002ve high errorot for perimear results wheut for those tmeter should b
Tn order to desitions (qualit
mbein, 1941; Sto simplify t
an et al., 201rent scales. Thsub-quantitie
e definition iptors are expture that manyt a clear meadness, does it ably they coulcognize in mo
Many image asis, fractal dment on the applications.
There are sevemensions, 3-d
13], Bund.
tion needs to
(left) LAT scompleted an
) conclude ths. It can be veter that keepen 3 differentterms/quantit
be treated with
TERMS, Qscribe the partative and qSneed & Folkthe complexit10) are usinghe terms are es are probabcan interpret
plained, and ty of the shap
aning on whameans that th
ld be on theorost of the case
analysis techndimension, tousage or con
eral shape desdimension ort
. A
o be accordin
scaning partind mesh gen
hat attributes vanish or at lp the error ast resolutions ties that invoh care.
DIS
QUANTITrticle shape i
quantitative) k, 1958). Allty of shape d
g three sub-qumorphology/
bly the best wt the whole these three sce descriptors t this descriphe angularityry but not in s.
IMAGEniques had beomography, nclusion to en
criptors and athogonal and
ng with the g
icles (Matsunerated. (Mat
like length east diminishs big as initiwere used in
olve the peri
SCUSSI
TIES ANDin detail, therused in the
l mathematicadescription. Suantities; one/form, roundnway to classif
morphologyales represenare presented
ptor defines, ey never ends?
reality. Physi
E ANALYeen used to detc., (Hyslipnsure the bes
also various td 2-dimension
goal and prec
ushima et al.,tsushima et a
when measurh using high rially. Johanss
n the same paimeter. Thus
ON
D DEFINIre are a numb literature (al definitionsSome authore and each dness and surfafy and describy. Common nt an option. Id with the same.g. when the Could they bical meaning
SIS describe the
p and Vallejost particle des
techniques to ns). Each tech
cision needed
, 2003), (righal., 2003)
ring digital iresolution jusson and Vall article obtainin
all quantitie
ITIONS ber of terms, (e.g. Wadell,s (quantitatives (Mitchell &
describing theace texture (Fbe a particle language is
It is evident inme name but ere is no uppbe more and of the quanti
particle shapo, 1997) butscriptor for g
capture the phnique presen
19
d in any work
ht) 3D scan
images presenst for diamete(2011) obtai
ng an unstabes relating th
quantities an, 1932, 1934es) are mode& Soga, 2005e shape but Figure. 1). Th
because not needed whe
n the reviewealso that ther
per limit in thmore angular
ities is difficu
pe, e.g. Fouriet there is no
geotechnical o
particles profints advantage
92
k.
nt er in le he
nd 4;
els 5; at he a
en ed re he r?
ult
er ot or
le es
Vol. 18 [2013], Bund. A 193 and disadvantages. 3-dimensions is probably the technique that provide more information about the particle shape but the precision also lies in the resolution; the equipment required to perform such capture could be more or less sophisticated (scanning particles laying down in one position and later move to complete the scanning or just falling down particles to scan it in one step). 3-dimensions orthogonal, this technique use less sophisticated equipment (compare with the previous technique) but its use is limited to particles over 1cm, also, information between the orthogonal pictures is not capture. 2-dimensions require non sophisticated equipment but at the same time the shape information diminish compare with the previous due the fact that it is possible to determine only the outline; as the particle measurements are performed in 2-dimensions it is presumed that they will lie with its shortest axis perpendicular to the laying surface when they are flat, but when the particle tends to have more or less similar axis the laying could be random.
Advantages on the use of image analysis are clear; there is not subjectivity because it is possible to obtain same result over the same images. Electronic files do not loose resolution and it is important when collaboration among distant work places is done, files can be send with the entire confidence and knowing that file properties has not been changed. Technology evolutions allowed to work with more information and it also applies to the image processing area were the time consumed has been shortened (more images processed in less time).
One important aspect in image analysis is the used resolution in the analysis due the fact that there are measurements dependent and independent on resolution. Thus, those dependent measurements should be avoided due the error included when they are applied, or avoid low resolution to increase the reliability. Among these parameters length is the principal parameter that is influences by resolution (e.g. perimeter, diameter, axis, etc.). Resolution also has another aspect with two faces, quality versus capacity, more resolution (quality) means more storage space, a minimum resolution to obtain reasonable and reliable data must be known but it depend on each particular application.
APPLICATIONS Quantify changes in particles, in the author’s thought, is one of the future applications due the
non-invasive methods of taking photographs in the surface of the dam’s slope, rail road ballast or roads. Sampling of the material and comparing with previous results could show volume (3D analysis) or area (2D analysis) loss of the particles as well as the form, roundness and roughness. This is important when it has been suggested that a soil or rock embankment decrees their stability properties (e.g. internal friction angle) with the loss of sphericity, roundness or roughness.
Seepage, stock piling, groundwater, etc., should try to include the particle shape while modelling; seepage requires grading material to not allow particles move due the water pressure but in angular materials, as it is known, the void ratio is great than the rounded soil, it means the space and the possibilities for the small particles to move are greater; stock piling could be modelled incorporating the particle shape to determine the bin’s capacity when particle shape changes (void ratio changes when particle shape changes) Modelling requires all information available and the understanding of the principles that apply.
Industry is actually using the particle shape to understand the soil behaviour and transform processes into practical and economic, image analysis has been included in the quality control to determine particle shape and size because the advantages it brings, e.g. the acquisition of the sieving curve for pellets using digital images taken from conveyor, this allows to have the
Vol. 18 [2013], Bund. A 194 information in a short period of time with a similar result, at least enough from the practical point of view, as the traditional sieving.
CONCLUSIONS • A common language needs to be built up to standardize the meaning on geotechnical field
that involve the particle shape.
• Based on this review it is not clear which one is the best descriptor.
• Image analysis tool is objective, make the results repeatable, obtain fast results and work with more amount of information.
• Resolution needs to be taken in consideration when image analysis is been carried out because the effects could be considerable. Resolution must be set according to the necessities. Parameters as perimeter can be affected by resolution.
• There are examples where particle shape has been incorporated in industries related to geotechnical engineering, e.g. in the ballast and asphalt industry for quality control.
FURTHER WORK Three main issues have been identified in this review that will be further investigated; the
limits of shape descriptors (quantities) influence of grading and choice of descriptor for relation to geotechnical properties.
Shape descriptors have low and high limits, frequently the limits are not the same and the ability to describe the particle’s shape is relative. The sensitivity of each descriptor should be compare to apply the most suitable descriptor in each situation.
Sieving curve determine the particle size in a granular soil, particle shape could differ in each sieve size. There is the necessity to describe the particle shape on each sieve portion (due to practical issues) and included in the sieve curve. Obtain an average shape in determined sieve size is complicated (due to the possible presence of several shapes) and to obtain the particle shape on the overall particle’s size is challenging, how the particle shape should be included?
Since several descriptors have been used to determine the shape of the particles but how is the shape related with the soil properties? It is convenient to determine the descriptor’s correlation with the soil properties.
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