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Field Leaching of Bricks and Concrete Containing Coal Fly Ash
Ruud Meij , Esther Kokmeijer, Leendert Tamboer and Henk te Winkel
KEMA Power Generation & Sustainables, P.O. Box 9035, NL 6800 ET Arnhem, the Netherlands, telephone +31-26-3562225, fax +31-26-4453659, e-mail: [email protected] KEYWORDS: leaching, field tests, laboratory tests, diffusion test, availability test, bricks, concrete, hydrology, coal fly ash SUMMARY In the Netherlands building materials must comply with leaching limits as laid down in the Buildings Materials Decree. The leaching behaviour of the building materials has to be determined by standardised tests at the laboratory. The results of these tests are used as input in formulas that calculate the cumulative emissions over 100 years. The question arises whether this approach is a good prediction of what will happen in the field. At KEMA a major research item is to investigate leaching behaviour under field conditions. This paper presents the results of field leaching of two types of bricks for five and a half years and of concrete for two years. For these three types of building material two forms are tested, one ordinary form and one in which 20% coal fly ash (CFA) is used. The results are compared between the different types of clay, between materials with and without CFA and between prolonged field tests and brief laboratory leaching tests. The use of CFA as a raw material in bricks and concrete increases the leaching of As, Mo and sulphate. Vanadium also shows this increase of leaching in bricks, but not in concrete. The effect of using CFA in one type of brick is that the Cr leaching increases, while in another type of brick and in concrete it decreases. In all cases and for all elements the leaching stays well below the limits as laid down in the Building Materials Decree, so CFA can well be used in building materials without contaminating the soil or surface water. Compared to the 5½ years field test, the extrapolation of the diffusion test to 5½ years gives a reasonable prediction of the leaching of molybdenum and vanadium; however, the diffusion test overestimates the leaching of arsenic and barium and it underestimates the leaching of chromium and sulphate.
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Field leaching behaviour ofField leaching behaviour ofbuilding materialsbuilding materials
Dr. Dr. Ruud Ruud Meij, Dr. Esther Meij, Dr. Esther KokmeijerKokmeijer,,Leendert Tamboer Leendert Tamboer B.B.ScSc. and. and Henk te Winkel Henk te Winkel B.B.ScSc
KEMA the NetherlandsKEMA the NetherlandsKEMA the Netherlands
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 2
ContentContent
ýý Conclusions Conclusions
ýý Leaching in lab versus field Leaching in lab versus field
ýý IntroductionIntroduction
ýý Building Materials Decree and leaching Building Materials Decree and leaching test test
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KEMAKEMA
Power GenerationsPower Generations
&&
SustainablesSustainables
ArnhemArnhem
Dolmen or megalithic grave in the Netherlands
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Buildings Materials Decree
Ä two limits one for building materials in contact with rain, surface water and /or ground water and one for buildings materials isolated from water
Ä two type of limits one for moulded products and one for unmoulded products
In order to prevent soil, groundwater and surface water
pollution limits are set for immissions into the soil for use
of primary, secondary and waste materials.
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Gives maximum immission levels for the soil
the next step is
translation of emission levels, to be determined via
column test for unmoulded materials, into immissionlevels according to the formula below:
Next) fh)aE(1550I **10S/L(mean*bN −−= =
10k
h1550
Ntk
Nexte1
e1f
i
•−
••
•−
−−
−=
Buildings Materials Decree
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type of leaching
test
Dutch column
test
Dutch cascade
test
EPA test 1) Dutch availability
test
L/S ratio 10 5x20=100 20 2 x 50
time scale in
years
5-50
short/medium
50-100/ 100-500
longterm
extreme long
period
worst case
demineralized
water at pH:1)
initial pH=4
alkaline
equilibrium-
pH
initial pH=4
alkaline
equilibrium pH
constant pH=5 constant pH=7
and pH=4
process upward flow
<2 cm•h-1
shake test 5x
refreshment
shake test shake test 2x
refreshment
time 3 weeks 5x23 hours 24 hours 2x3 hours
1) the pH is adjusted by adding HNO3; for the EPA test this is a deviation from the prescribedacetic acid; for some ashes the equilibrium pH is acid, but those ashes are not taken intoconsideration in these experiments, because they are hardly produced any more.
Characteristics of the various leachingtests for unmoulded materials
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For moulded materials one For moulded materials one
have to perform a tank leaching have to perform a tank leaching
test during 64 days and test during 64 days and
calculate the diffusion calculate the diffusion
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E(64d) = db·Ebes·√√(De/ππ)·√√t
Translation from laboratory test into emission
E(64d) = emission as determined by the diffusion test for 64 days
db = density of the material (kg.m-3)
Ebes = emission as determined by the availability test (mg.kg-1)
De = effective diffusion coefficient
t = contact time (s).
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 10
Translation from emission into immissions
Ical.(Y) = Edif(64d)·fext,v(h,x%,De)·ftemIcal.(Y) = calculated immissions after Y years in mg.m-2
Edif(64d) = calculated diffusion after 64 days in mg.m-2
fext,v(h,x%,De) = extrapolation factor of 64 days to Y years taking into con-
sideration the size (high) of the building (h), wet periods
(x%) and the possible change in De (see equation (1))
ftem = correction factor for the temperature difference of the labo-
ratory and field conditions
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code type mass(kg)
composition PFA
sand lime bricks 0-60% SDA
A half-bricks 182 bronze fired clay
B half-bricks 178 bronze fired clay 20%
C half-bricks 185 red fired clay
D half-bricks 178 red fired clay 20%
E reference 178 trespa (plastic)
F hollow wall 2*178 bronze fired clay 20%
G concrete Portland cement CEM I 32,5
H concrete Portland cement CEM I 32,5 20% + o.v. cement320 kg/m3
I concrete Portland cement CEM I 32,5, 20% recycledconcrete granules as artificial gravel
20% + o.v. cement320 kg/m3
J concrete Portlandcement CEM I 32,5, 100% recycledconcrete granules as artificial gravel
20% + o.v. cement320 kg/m3
The composition of the building materials
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Availability test of clay bricks
0
2
4
6
8
10
12
14
16
18
A s B a C r M o V S O 4
mg
/kg
(g
/kg
S
O4
)
bronze fired
bronze fired + PFA
red fired
red fired + PFA
Availability test of clay bricks
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 13
code composition As Ba Cr Mo V SO42-
A bronze-fired clay 2.3 0.1 8.8 6.5 9.1 2.0
B idem + 20% CFA 1.5 6.8 40.8 22.0 4.3 3.9
C red-fired clay 0.4 0.2 9.2 8.4 5.2 3.0
D idem + 20% CFA 1.0 0.2 58.7 17.9 22.6 1.0
The calculated diffusion coefficientDe (10–12 m.s –1)
for the various types of bricks
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 14
diffusion test of clay bricks
0
10
20
30
40
50
60
70
80
As Ba Cr Mo V SO4
mg
/m2
(g/m
2 S
O4)
bronze fired
bronze fired + PFA
red fired
red fired + PFA
mortal
Diffusion test of clay bricks
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 15
time 64 days
BMD1) test2)
wall U1a U2,1b A B, F C D mortal
As 41 140 20.1 18.6 8.2 14.8 <0.9
Ba 600 2000 6.5 32.3 5.2 6.6 50
Cd 1.1 3.8 0.1 <0.05 0.12 <0.05 <0.05
Co 29 95 <1.1 <1.1 <1.1 <1.1 <1.1
Cr 140 480 3 3.2 4.3 3 1.9
Cu 51 170 3 1.2 <1.1 <1.1 <1.1
Hg 0,4 1.4 <0.06 <0.06 <0.06 - <0.06
Mo 14 48 4.7 14.3 3.3 10.3 <2.3
Ni 50 170 <1.7 <1.7 <1.7 <1.7 <1.7
Pb 120 400 15.6 6.9 9 3.8 <2.3
Sb 3.7 12 <1.7 <1.7 <1.7 <1.7 <1.7
Se 1,4 4.8 <1.1 <1.1 <1.1 <1.1 <1.1
Sn 29 95 <1.1 <1.1 <1.1 <1.1 <1.1
V 230 760 51.4 73.6 59.9 66.2 4.8
Zn 200 670 3.1 <2.9 8 <2.9 <2.9
SO42- 27000 80000 5096 3184 2322 1603 793
Limitsaccordingto the
BuildingsMaterials
Decreeand lab.
testresults inmg.m-2
mg.mmg.m-2-2
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Hydrology of the walls
type of wall amount ofleachate
amount ofevaporation
reference (plastic) 100% 0%
concrete 77% 23%
half-bricks 17% 83%
hollow wall 1.3% 90-94%
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 20
0
3
5
8
10
0 50 100 150 200 250 300weeks
dif
fusi
on
in m
g/m
2
A bronze
B bronze+CFA
C red
D red+CFA
F red hollow
As
Cumulative Field leaching of bricks
in 5½ years under field conditions
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 21
Cumulative
Fieldleaching of
bricks
in 5½years
under fieldconditions
0
2 5
5 0
7 5
1 0 0
dif
fus
ion
in
mg
/m2
V
0
0
1
1
1
dif
fus
ion
in
mg
/m2
A bronze
B bronze+CFA
C red
D red+CFA
F red hollow
B a
0
3
5
8
1 0
dif
fus
ion
in
mg
/m2
A s
0
1 0
2 0
3 0
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0
dif
fus
ion
in
mg
/m2
Cr
0
1 0
2 0
3 0
dif
fus
ion
in
mg
/m2
M o
0
5
1 0
1 5
2 0
2 5
3 0
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0w e e k s
dif
fus
ion
in
g/m
2
S O4
2-
mg.mmg.m-2-2
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 22
0
10
20
30
0 50 100 150 200 250 300weeks
dif
fusi
on
in m
g/m
2Abronze
Bbronze+CFA
C red
Dred+CFA
F redhollow
Cr
Cumulative Field leaching of bricks
in 5½ years under field conditions
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 23
Cumulative Field leaching of bricks
in 5½ years under field conditions
As
0,0%
0,5%
1,0%
1,5%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70
L/S in l/kg
field
leac
hin
g in
%
of
avai
lab
ility
tes
t
A bronze B bronze+CFA C red D red+CFA F hollow+CFA
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 24
Cumulative
Fieldleaching of
bricks
in 5½years
under fieldconditions
As
0,0%
0,5%
1,0%
1,5%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70
fie
ld l
ea
ch
ing
in
% o
f
av
ail
ab
ilit
y t
es
t
B a
0,0%
0,1%
0,1%
0,2%
0,2%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70
fie
ld l
ea
ch
ing
in
% o
f
av
ail
ab
ilit
y t
es
t
A bronze
B bronze+CFA
C red
D red+CFA
F hollow+CFA
C r
0%
40%
80%
120%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70L/S in l /kg
fie
ld l
ea
ch
ing
in
% o
f a
va
ila
bil
ity
te
st
Mo
0%
5%
10%
15%
20%
25%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70
fie
ld l
ea
ch
ing
in
% o
f a
va
ila
bil
ity
te
st
V
0%
5%
10%
15%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70
fie
ld l
ea
ch
ing
in
% o
f
av
ail
ab
ilit
y t
es
tS O 4
2-
0%
25%
50%
75%
100%
0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70L/S in l /kg
fie
ld l
ea
ch
ing
in
% o
f a
va
ila
bil
ity
te
st
1.51.5
0.20.2
120120
2525
1515
100100
mg.mmg.m-2-2
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 25
0,0
0,1
0,2
0,3
0 20 40 60 80 100 120weeks
cum
ulat
ive
diff
usio
n in
mg/
m2
G concrete
H concrete+CFA
Mo
Cumulative Field leaching of concrete in 2years under field conditions
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Cumulative
Fieldleaching ofconcrete
in 2 years
under field
conditions
0,0
0,1
0,2
0,3c
um
ula
tiv
e d
iffu
sio
n i
n m
g/m
2
G Concrete
H concrete+CFA
As
0,0
2,0
4,0
6,0
cu
mu
lati
ve
dif
fus
ion
in
mg
/m2
G concrete
H concrete+CFA
C r
0,0
0,1
0,2
0,3
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0w e e k s
cu
mu
lati
ve
dif
fus
ion
in
mg
/m2
G concrete
H concrete+CFA
M o
0,0
1,3
2,5
3,8
5,0
cu
mu
lati
ve
dif
fus
ion
in
mg
/m2
G concrete
H concrete+CFA
V
0,0
0,5
1,0
1,5
2,0
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0w e e k s
cu
mu
lati
ve
dif
fus
ion
in
g/m
2
G concrete
H concrete+CFA
`
S O4
-2
mg.mmg.m-2-2
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 27
Limits according to the Buildings MaterialsDecree and field test results in mg.m-2
time 100y 5.5 years3) 2y
BMD test field test field field test field test field field field
wall A A B B F C C D D G H
As 435 24.9 3.4 23.1 7.8 0.6 10.2 1.2 18.4 5 0.12
Ba 6300 8.1 0.6 40 0.7 0.2 11.6 0.6 14.8 0.7
Cd 12
Co 300
Cr 1500 3.7 11 4 17.1 6.9 5.3 26.9 3.7 15.7 1.2 0.8
Cu 540
Hg 4.5
Mo 150 5.8 5.7 17.7 22.2 2.7 4.1 7.6 12.8 17.6 0.1 0.2
Ni 525
Pb 1275
Sb 39
Se 15
Sn 300
V 2400 63.8 58.6 91.3 95.5 21.6 74.3 36.2 82.1 68.2 4.2 3.7
Zn 2100
SO42- 100000 6320 17000 3950 25300 6000 2880 23700 1990 23900 1200 1600
mg.mmg.m-2-2
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 28
AB + F+
CD+
As
CrV0%
200%
400%
600%
800%
1000%
1200%
1400%
As
Ba
Cr
Mo
V
SO4
Field leaching in % of diffusion test (5,5 years)
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 29
Field leaching in % of diffusion test (5,5 years)
AB + F+
CD+
As
Cr
V0%
20%
40%
60%
80%
100%
120%
140%
160%
180%
200%
As
Ba
Cr
Mo
V
SO4
Lexington, Kentucky * October 22-24 2001 International Ash Utilisation Symposium 30
ConclusionsConclusions
Thank you for your attention
ýý CFA (20%) in bricks and concrete can meet the strict Dutchleaching limits
ýý the leaching of As, Mo and sulphate increases. V alsoshows this increase of leaching in bricks, but not in concrete.The leaching of Cr is however rather complicated; in one clay itshows an increase in leaching after adding CFA and in anotherclay and in concrete it shows a decrease.
ýý the results of the diffusion test extrapolated to the observed5½ years give a reasonable pre-diction of the leaching of Mo andV; however, it overestimates the leaching of As and Ba and itunderestimates the leaching of Cr and sulphate, with respect tothe half-brick wall.