/^^v
'*)
Case Study
20
o
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o
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ci
Aardelite Technology
Turning a residue into a building material
1.1. Introduction and objective
Aardelite pellets were used as natural gravel
replacement for the construction of a housing
compound consisting of 120 units for re-
tired people at Dronten in the Netherlands.
The compound consists of multiple-story
buildings and is surrounded by single-level
houses.
In consultation with the Ministry of Housing,
Land Development and Environmental
Affairs and the owner, "Oostelijk Flevoland"
Housing Corporation, it was decided that
Aardelite gravel would be used in a number
of houses to demonstrate the behaviour of
Aardelite gravel in concrete construction.
In order to compare the workability and
final quality of Aardelite concrete to tra-
ditional concrete, the walls of four single-
level houses were made with Aardelite
concrete; an identical block of four houses
was made with traditional concrete.
The objective of this demonstration project
was to prove that with the use of Aardelite
gravel, the same concrete qualities would
be met as with traditional natural gravel
concrete, without special additives or
precautions. Both blocks of houses were
executed with the same type and quantity
of cement, the same reinforcement, and no
addition of plasticizers.
A number of walls were poured in both blocks of houses using a concrete bucket.
In order to demonstrate the workability of Aardelite's round shaped gravel dur-
ing pumping, one concrete pour was executed with a concrete pump.
i
April
2008
Page 1 of 14
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Aardelite Technology
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Case Study
20
1.2. Definition of the building project
Project: Housing compound Dronten, 120 houses for retired people
Owner: Housing Corporation "Oost Flevoland"
Design: Van Heelsbergen-Jansen Architects, Arnhem
Contractor: H. de Vries B.V, Emmeloord
Ready-Mix plant: Flevoland B.V, Lelystad / Dronten
The sizes, reinforcement and pouring data are shown in the lay-out and table below.
wan
ctrtflii [c tt
.
mac*
house no.
g 15 em
: C3
C2
33Q
23cm
C1
y I
15cm
8S
56
4J5
23cm
r:
330
15cm
3JO
23cm
A3
5* 1
435
15cm
A2
W
4J5
:
330
Mark
Al
A2
A3
Bl
B2
B3
Cl
C2
C3
Wall
Inner leaf of
external wall
Inside wall
Separating wall
Inside wall
Separating wall
Inside wall
Separating wall
Inside wall
Inner leaf of
external wall
House no.
54
54
54
55
55
56
56
56
57
57
57
Length
[meter]
11.40
10.30
10.10
10.30
10.60
10.30
10.10
10.30
11.40
Thickness,
[mm]
150
150
230
150
230
150
150
150
150
Lock-woven
Mesh
[mm]
08-20/25
08-20/25
None
08-20/25
None
08-20/25
None
08-20/25
08-20/25
1.3. Composition and quality of the concrete
The required concrete quality was B 17.5 (Dutch standard) with 320 kg cement per m3 concrete.
In those cases where the shuttering (concrete pouring mold) had to be removed the next morning due to the
weather conditions, a 50/50 mixture of blast furnace cement (HOA) and portland rapid hardening cement
(PCC) was used.
There were no additives added to the concrete mixtures.
The composition and quality of the Aardelite concrete was kept the same as the concrete using the tradi-
tional natural gravel.
Page 2 of 14
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Case Study
20
Aardelite Technology
Aardelite pellets size 4-16 mm were used as natural gravel replacement.
See attachments I to VI for the mixture calculations of the Aardelite based concrete and screen analyses of
the aggregate of three individual batches.
1.4. Execution
The Aardelite concrete pours were performed in
three days; every day three concrete pours were
done, making nine walls in total.
Present at the first concrete pour were:
Supervisor: E.J. Westerink, for the principal
Manager: B. Maandag, for the contractor
Chief foreman: J. Klasen, for the contractor
Foreman: A. Wakker, for the contractor
Building inspectors: Mr. van Tol and Mr. de Boer
Concrete technologist: A.Th. de Haan
Vliegasunie: J. Dubbers and B. Scheurs
Consultant: Prof. ir. J.A.H. Hartmann
Project manager: Ir. A.B. Winkel, for Aardelite BV
All vails appeared to be perfectly smooth after removal of the
shuttering elements.
Shuttering elements were used throughout the whole project.
The first concrete pour was done in the early afternoon using a concrete bucket. The next day, after 17 hours
curing, the shuttering elements were removed.
The second concrete pour was done on a Friday in the early afternoon, using a concrete bucket. The following
Monday morning, after 65 hours curing, the shuttering elements were removed.
The third concrete pour was pumped using a mobile Schwing-Stetter concrete pump. The next day, after 17
hours curing, the shuttering elements were removed.
1.5. Physical properties of the cured concrete
Compressive strength was measured after 7, 14 and 28 days of curing. See attachments VII, VIII, and IX
for an overview of the test results.
A visual inspection after two months revealed no differences between the Aardelite concrete surface and the
traditional natural gravel concrete.
1.6. Evaluation of Aardelite based concrete
The workability of Aardelite concrete is good and comparable with natural gravel concrete; both concretes
have identical water/cement ratios. The workability of the Aardelite concrete when using a mobile concrete
pump for pouring was excellent; in fact, due to the round shape of the Aardelite pellets, operation of the
pump was even smoother than with traditional concrete. Neither the foreman and workers on site nor the
operators of the ready mix concrete plant noticed any difference in workability between Aardelite concrete
and traditional concrete when weighing, dosing, or mixing in the ready mix concrete plant, or in pouring
using a bucket.
The strength development and final strength of Aardelite concrete is comparable with natural gravel concrete.
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Aardelite Technology
Case Study
20
1.7 Supplementary research of the cured concrete
1.7.1 Air sound insulation measurements
In order to compare the Aardelite concrete properties with traditional concrete, air sound insulation mea-
surements were performed by TNO/TPD (Institute of Applied Physics) on Aardelite as well as natural
gravel concrete.
The table below shows an overview of the measured air sound insulation indices for air sound between the
separating walls of the houses on ground level (horizontal direction).
Measurement
1
2
3
4
5
6
7
8
Concrete
type
Taditional
Taditional
Taditional
Taditional
Aardelite
Aardelite
Aardelite
Aardelite
Transmitting-room
Living room
Kitchen
Living room
Kitchen
Living room
Kitchen
Living room
Kitchen
Receiving-
room
Living room
Kitchen
Living room
Kitchen
Living room
Kitchen
Living room
Kitchen
Insulation-
index I lu [db]
+4
+6
+7
+9
+5
+3
+6
+5
The conclusion of TPD is that both the houses built with Aardelite concrete and those built with traditional
concrete in Dronten are within limits of the Dutch standard NEN 1070 (Ilu = OdB). The houses with Aardel-
ite concrete walls showed on average a slightly lower Ilu value than the houses with traditional concrete
walls (the difference was 1.7 dB). The difference is partly due to the difference in concrete density, with
Aardelite concrete at 2100 kg/m3 and traditional concrete at 2400 kg/m3. The remainder of the difference is
most likely due to measurement inaccuracies. The course of the insulation curve in the measured situations
with or without Aardelite concrete is not significantly different.
1.7.2 Determination of the coefficient of heat conductivity
The coefficient of heat conductivity was also measured by TPD. The average X values are for:
Aardelite concrete X = 0.84 W/mK
Traditional concrete X = 1.0 W/mK
(W/mK: Watt per meter Kelvin)
Based on the lower density of the Aardelite pellets, the expected heat conductivity of the Aardelite con-
crete is 10% to 20% lower.
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Aardelite Technology
Case Study
20
1.7.3 Anchorage of fasteners
The building industry uses significant
numbers of plugs and anchors. To judge
the workability and behaviour of the
different types of plugs and anchors in
Aardelite concrete, the Fisher company
performed a short study.
It was concluded that the behaviour and
workability in both concrete types was
the same, although drilling and cutting
in Aardelite concrete is easier because
Aardelite pellets are not as hard as natu-
ral gravel.
2.1 Aardelite pellets
The Aardelite pellets used for this project
were made from pulverized coal fly ash made
available at a power station in Nijmegen,
the Netherlands. The composition of the
Aardelite pellets was as follows:
fly ash
CaO
water
79.7%
3.3%
17.0%
The Aardelite pellet properties were as
follows:
Pellet strength 4 MPa
Bulk density 1050kg/m3
(as produced)
Specific density 1700kg/m3
Moisture content 17%
(water as % of total weight)
This picture shows the different types of fasteners used.
Aardelite pellets being transported.
After production, the Aardelite pellets were transported by truck to Flevoland Ready mix batching plant
for intermediate storage.
3.1 Aardelite process description
The pellets used in the concrete are made using the Aardelite process. The Aardelite technology is based on
the activation and control of pozzolanic reactions in the fly ash/lime/water mixture by using the pozzolanic
properties of fly ash. During these reactions (dissolution of silicon and aluminum in the presence of lime
and water), a tobormorite-like gel is formed which, on a micro scale, is able to 'cement' the 'inert' particles.
The resulting product is a stone-like matrix.
Page 5 of 14
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Aardelite Technology
Case Study
20
The reaction mechanisms can be summarized as follows:
CaO + H2O
SiO2 + Ca(OH)2 + H20
Si(OH)4 + CaO + H20
CaO + H2O
2AI2O3 + 3Ca(OH)2 + 3H20
4AI(OH)3 + 3 CaO + H2O
> Ca(OH)2
> Si(OH)4 + CaO
> CaO*SiO2*3H2O (calcium silicate hydrate)
> Ca(OH)2
> 4AI(OH)3 + 3CaO
> 3CaO «2AI2O3*7H2O (calcium aluminate hydrate)
These reactions are accelerated at a temperature of 90° Celsius and 100% relative humidity.
The Aardelite production process is presented below.
RECYCLE
EMBEDDIN(
MATERIAL
BINDEI
\
/
EMBEDDING
MATERIAL
CURING
AARDELITE PROCESS
OVERSIZE
PREHEATI
AARDELITE PELLETS
The Aardelite process is a continuous process where fly ash, recycled embedding material (fly ash which
has been used as embedding material), and lime are fed into the mixer in accordance with the pre-deter-
mined recipe. In the first mixing phase, fly ash and lime are mixed thoroughly. After the addition of water,
the second mixing phase takes place, which results in the even distribution of the micro-sized particles of
fly ash and lime.
The material from the mixer, the so called green mix, is fed onto the pelletizer through a delumper in order
to prevent conglomerated green mixture from entering the pelletizer. On the pelletizing disk, pellets of the
desired size range are formed. The mechanism of the pelletizing process is based on the conglomeration of
fine particles through rotating the particles under an angle, while spraying water. The size of the pellets is
determined by the amount of water added at the pelletizing disk and the rotating speed of the pelletizer.
Page 6 of 14
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Aardelite Technology
Case Study
20
Pellets leaving the pelletizer, the so-called green pellets, are embedded in dry fly ash to prevent them from
sticking together during the curing process. In the rotary preheater, where the embedding process takes
place, steam is injected to preheat the embedded green pellets to 90° Celsius. The heated embedded green
pellets are fed into the curing silo, where the desired pozzolanic reactions take place. The time required for
these reactions is about 20 hours. The silo is designed in such a way that a continuous mass flow is assured,
as well as the required retention time.
The embedded cured pellets from the
curing silo are fed into a rotary screen to
separate the pellets from the embedding
fly ash, after which this fly ash is re-used
in the mixer again. The cured pellets are
separated in the desired size ranges. Over-
size pellets are crushed and returned to
the rotary screen. The process is free of
any waste streams.
The Aardelite pelletizer.
ATTACHMENT I: First Concrete Pour
Flevoland B.V. Dronten.
Contractor: Bouwbedrijf H. de Vries B.V. Emmeloord
Project: Housing compound for retired people, Dronten.
Calculation of Aardelite concrete mixture:
165
165
Air
Water
Total volume
kg
kg
1%
Blast furnace cement
Portland cement
(w/c ratio 0.50)
Remaining for aggregate
=
=
=
=
56
52
10
163
281
719
Itr
Itr
Itr
Itr
Itr
Itr
Calculation of the aggregates:
38% sand
273.2 Itr
x2.64 kg/ltr
721 kg dry sand
30 kg moist (4.2%)
751 kg sand incl. moist
62% Aardelite
445.8 Itr
x 1.70 kg/ltr
758 kg dry Aardelite
129 kg moist (17%)
887 kg Aardelite incl. moist
Water
163 Itr required
- 30 (water content sand)
- 129 (water content
Aardelite)
+ 136 (absorption 18% in
Aardelite)
140 Itr water
Weigh out (rounded off) per m3 concrete:
165 kg BF cement
165 kg PC cement
750 kg sand
890 kg Aardelite
140 Itr water
Note: lkg = 2.204 Ib
I Itr = 0.26 US gallon
1m3 = 1,000'Itr
1 mm = 1,000 jum (micron)
1 mm = 0.0394 inch
Page 7 of 14
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Aardelite Technology
2tPR<*2
Case Study
20
ATTACHMENT II, First Concrete Pour Screen Analyses
in1, c oar * sand : Lowr Rhine FfiC
A^delilr i-I6 : Nifaipeet METH
Dronten
tfiilr utter Baurwbedrijl B.de Vrit* B.V.
subject »'AIL5
laboratory;
NENK*l>
C J- 'j
CM
ca
C4
2 mm
1 JWi
MO Mm
2LO ^T,
125 um
F
*
^n.
7.4
16. i
25- 2
56,5
93.*
91M
3GI.S
3.02
Ajrdf
li ItC
0.0
f.l
71.1
%.7
97,1
97.2
97,5
ys.D
o*.a
663,1
6.1,3
sand
2.96
...'
10.72
:-..;.
.%.-,-
37.77
LL*.«
ll*-7
42 %
A.Er
0.0
3.7S
M.U
59.96
h.'.?'..
60.26
60.4S
60-76
61,26
4ILJ2
-.Li
.-rnx
5.0
>,7S
HU.H5
62.92
1 ! . -.'.
70.9S
JU92
96.33
>9J33
525-80
H IJ
mix
0.0
Mt
j'-.!. '.
62.9
66."
71.0
i"l.9
**,3
r^.V
>25.S
5,2ft
sjcve optn4ngj m Jog scale
MDtMla
organic
none
none
Ja^.gravel ii'
and
- %
Aard«JJte 62 *
air
05 i
1-0 %
a. by composition
b, by
B
PC/BCF 165/165 *9
sand 72) hfl
?>£ 10
kg
TOT.wie-f 299 in
addjiive oon*
brand
i]bM?rp1i:Dn
w/c
Ur
stump
Page 8 of 14
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Aardelite Technology
Case Study
20
ATTACHMENT III, Second Concrete Pour
Flevoland B.V. Dronten.
Contractor: Bouwbedrijf H. de Vries B.V. Emmeloord
Project: Housing compound for retired people, Dronten.
Calculation of Aardelite concrete mixture:
320
Air
Water
Total volume
kg
1%
Blast furnace cement
(w/c ratio 0.5 2)
remaining for aggregate
=
=
=
109
10
166
285
715
Itr
Itr
Itr
Itr
Itr
Calculation of the aggregates:
38% sand
271.7 Itr
x2.64 kg/ltr
717 kg dry sand
26 kg moist (3.6%)
743 kg sand incl. moist
62% Aardelite
443.3 Itr
x 1.70 kg/ltr
754 kg dry Aardelite
128 kg moist (17%)
882 kg Aardelite incl. moist
Water
166 Itrrequired
- 26 (water content sand)
-128 (water content
Aardelite)
+ 136 (absorption 18% in
Aardelite)
148 Itr water
Weigh out (rounded off) per m3 concrete:
320 kg BF cement
745 kg sand
880 kg Aardelite
148 Itr water
Note: lkg = 2.204lb
1 Itr = 0.26 US gallon
1m3 = 1,000 Itr
1 mm = 1,000 pm (micron)
1mm =0.0394 inch
Page 9 of 14
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Aardelite Technology
ATTACHMENT IV, Second Concrete Pour Screen Analyses
2tPR<*2
Case Study
20
cwrwiand
Aardelhe ti-|
Lower Rhine FTC
Nunipoet MIITH
laboratory]
contracior
subject
DroAien
Bouwbtdnjf H.ite Vrirv R-V.
WALLS
lien?* ace.
cai.s
cie
Cl
C4
2 run
i (run
500 |*n
250^
125 (jm
F
*
Mind
?,&
16.3
25-2
56,5
93,6
99,4
301, S
3-0?
Aarde
lite
,,',
f-.l
71.1
96,?
97. J
"7.2
97,5
"^
'.'':,'
M VI
6-63
3S %
sand
2.96
6.19
10.72
21,47
35,57
37.77
IIM.6S
JJ4-.7
62 %
;..-,
^n
**.*j
>9.9<-
.,:.. r.
60.2
60.45
60.76
61.26
411.12
MM
mix
','-,
,, '-.
64,45
f-^2
M.S9
703S
ai,?2
%-33
99,03
523JC
525.4
mix
0,0
3.S
W.J
62,9
rK-
71.0
31,9
96-3
99.0
3 25, a
5.26
krt
02 4 & i ia 12 M ie
i 1 j 1 j L_J , h
» J? M
2B rrm
y.
vr,
zso
a 4
ncvt
in tug if
3i,s
input itiet
none
fjone
3S %
Aardelile 62
135 <
air
a. by coftiposnion
b. by coinpT^K
Class B 17,5ilre R111
PC/flCF 320 tg
brand CEMY-A
717 fcfl
Aird«ljt« 7-ii kg
gravel ^_ If
lot .voter 302 IT
«dditi.ve none
qty _
absorption |J£ 11 r
*-/c ta.ua 0.52
sJump 1 2d rrw
Page 10 of 14
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Aardelite Technology
Case Study
20
ATTACHMENT V, Third Concrete Pour
Flevoland B.V. Dronten.
Contractor: BouwbedijfH.de Vries B.V. Emmeloord
Project: Housing compound for retired people, Dronten
Calculation of Aardelite concrete mixture:
160
160
Air
Water
Total volume
kg
kg
1%
Blast furnace cement
Portland cement
(w/c ratio 0.50)
Remaining for aggregate
=
=
=
=
54
51
10
160
275
725
Itr
Itr
Itr
Itr
Itr
Itr
Calculation of the aggregates:
38% sand
275.5 Itr
x2.64 kg/ltr
727 kg dry sand
28 kg moist (3.9%)
755 kg sand incl. moist
62% Aardelite
449.5 Itr
x 1.70 kg/ltr
764 kg dry Aardelite
128 kg moist (16. 8%)
892 kg Aardelite incl. moist
Water
160 Itr required
- 28 (water content sand)
-128 (water content
Aardelite)
+ 136 (absorption 18% in
Aardelite)
140 Itr water
Weigh out (rounded off) per m3 concrete:
160 kg BF cement
160 kg PC cement
755 kg sand
890 kg Aardelite
140 Itr water
Note: lkg = 2.204lb
1 Itr = 0.26 US gallon
1m3 = 1,000 Itr
1 mm = 1,000 nm (micron)
1 mm = 0.0394 inch
Page 11 of 14
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2tPR<*2
Case Study
20
Aardelite Technology
ATTACHMENT VI, Third Concrete Pour Screen Analyses
trfigiitt c oaf s* sand : Later Rhirw FEC
AafdsJjtt ti.|6 : Nunipert N'ETH
nr;
eanuaet ; Bouwbedrijl H.dc Vnes B.V,
subject WALLS
ace.
NEN2HQ
C31.S
Cft
SOQm
urn
land
MI
it.s
93.6
SOLS
3.02
1 ite
9.0
7LJ
96.7
n %
san
-------
Aardelite Technology
Case Study
20
ATTACHMENT VII
Flevoland B.V. Dronten
Aardelite concrete mixture compressive strength of the first pour.
Load number
Quantity
Water dosing
Concrete mix:
Slump
Shake
Temperature
Air
Spec, density
Test cubes:
Strength after:
7 days
14 days
28 days
1
6m3
140 Itr
140mm
390mm
12° C
0.7 %
2. 12 kg/ltr
Spec.
density
[kg/ltr]
~
~
2.17
Compr.
strength
[Mpa]
~
~
40.8
2
6m3
135 Itr
130mm
390mm
12° C
1.0%
2. 11 kg/ltr
Spec.
density
[kg/ltr]
2.15
2.14
2.16
Compr.
strength
[Mpa]
33.7
40.8
46.3
3
6m3
135 Itr
100mm
330mm
12° C
Spec.
density
[kg/ltr]
~
~
2.15
Compr.
strength
[Mpa]
~
~
44.7
The average compressive strength after 28 days was 43.9 MPa.
ATTACHMENT VIII
Flevoland B.V. Dronten
Aardelite concrete mixture compressive strength of the second pour.
Load number
Quantity
Water dosing
Concrete mix:
Slump
Shake
Temperature
Air
Spec, density
Test cubes:
Strength after:
7 days
14 days
28 days
1
6.5m3
148 Itr
140 mm
430 mm
12° C
0.9 %
2. 11 kg/ltr
Spec.
density
[kg/ltr]
2.15
2.13
2.14
Compr.
strength
[Mpa]
23.5
31.4
34.1
2
6.5m3
148 Itr
130mm
420 mm
12° C
Spec.
density
[kg/ltr]
~
~
2.13
Compr.
strength
[Mpa]
~
~
33.7
The average compressive strength after 28 days was 33.9 MPa.
Page 13 of 14
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Aardelite Technology
Case Study
20
ATTACHMENT IX
Flevoland B.V. Dronten
Aardelite concrete mixture compressive strength of the third pour.
Load number
Quantity
Water dosing
Concrete mix:
Slump
Shake
Temperature
Air
Spec, density
Test cubes:
Strength after:
7 days
14 days
28 days
1
9m3
140 Itr
130mm
440mm
12° C
1.0%
2. 13 kg/ltr
Spec.
density
[kg/ltr]
2.18
2.17
2.18
Compr.
strength
[MPa]
28.6
36.5
39.6
2
6m3
140 Itr
140 mm
450mm
12° C
Spec.
density
[kg/ltr]
~
~
2.20
Compr.
strength
[MPa]
~
~
36.1
The average compressive strength after 28 days was 37.8 MPa.
Submitted By:
Rene van den Bos, Director
Aarding Lightweight Granulates BV
P.O. Box 29
8070 AA Nunspeet
The Netherlands
Website: www.aardinglg.com
Email: info@aardinglg.com
COAL COMBUSTION
PRODUCTS PARTNERSHIP
This coal ash utilization case study is a selection of the Coal Combustion Product Partnership. For
more information, consult C2P2 web site at http://www.epa.gov/epaoswer/osw/conserve/c2p2/
Page 14 of 14
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