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CDW RECYCLED AGGREGATES FOR DRY CAST CONCRETES
Sérgio Angulo
BACKGROUND
• Most of production of aggregates is destined for cementitious materials.
• The consumption of aggregate in dry cast concrete represents the 24% of Brazilian total aggregates' consumption
• Dry cast concretes are ecoefficient
– compaction permits reduction of water and cement consumption.
http://anepac.org.br/wp/agregados
ECOEFFICIENCY IN CONCRETE
0,0
2,5
5,0
7,5
10,0
12,5
15,0
17,5
20,0
0 20 40 60 80 100 120
BI (k
g.m
-3.M
Pa
-1)
Compressive strenght (MPa)
Literature - Brazil
Literature - International
Ready-mix concrete 1
Ready-mix concrete 2
250kg/m³
Ready mixplastic
Site mixing
Waste
Rolled
DAMINELI, B. L. KEMEID, F. M. AGUIAR, P. S.; JOHN, VANDERLEY M. Measuring the eco-efficiency of cement use. Cement and Concrete Composites, v. 32, n. 8, p. 555-562, 2010.
DRY CAST CONCRETES
• Strength and porosity of dry concretes are governed by “mobility of dry mix” and “quality of aggregates”
TUCEK e BARTAK (1991) adaptado
MOBILITY OF DRY MIX
• Influenced by particle size distribution of aggregates
LARRARD (1999); OLIVEIRA et al. (2000)
WAYS TO IMPROVE MOBILITY OF DRY MIX
• Sieving
Heterogeneous and porous CDW recycled aggregates are sieved in many particle size fractions
CDW RECYCLED AGGREGATES
Cement paste (porous)
Granite(non porous)
Cement- Granite(non liberated)
D < 2,0 g/cm³ D > 2,6 g/cm³2,0 < D < 2,6 g/cm³
ABS < 5%ABS > 15% 15% < ABS < 5%
Bricks Tile/shingleBlocks
D < 1,5 g/cm³ D > 1,9 g/cm³1,5 < D < 1,9 g/cm³
ABS < 14%ABS > 24% 24% < ABS < 14%
ANGULO (2005) –tese doutorado
http://dx.doi.org/10.1590/S1678-86212013000200006
WAYS TO IMPROVE CDW RECYCLED AGGREGATES
• Thermal treatment and/or milling
– Weaken porous cement paste (cracks)
– Selective comminutionof porous cement paste (softer phase).
– Natural granite aggregates (harder phase)
http://dx.doi.org/10.1016/j.resconrec.2014.06.003
WAYS TO IMPROVE CDW RECYCLED AGGREGATES
• Density separation of porous particles– Gravity separation using wet jigs.
Light fraction is a mixed fraction of red ceramic and cementitious particles. It contains higher porosity.Heavy fraction is also mixed, but with higher amount of natural rock aggregates. It contains lower porosity.
• Crushing of porous particles– Destroy porosity of cement and red ceramic porous
particles.
– Transform coarse fraction into less porous sand or powder fraction.
Objective of Research
Compare characteristics of dry cast concretes formulated with CDW aggregates
obtained from different recycling strategies (sieving and density/crushing).
Experimental Planning
• Sampling CDW recycled aggregates (< 9 mm)
– Mass reduction (horizontal piles)
– Representative mass (Pierre Gy theory)
0
1
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1000
10000
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00
0,0
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0,0
90
0,1
00
Rep
rese
nta
tive
mas
s (k
g)
Concentration of organic materials (in kg/kg)
d95=32 mm
d95=16 mm
d95=4 mm
DOI 10.1617/s11527-008-9417-3
Experimental Planning
• Density Separation • 20 kg of CDW aggregates
• Operation conditions– With fines (< 2mm) or not
– Pressure (0,01 – 0,1 bar)
– Frequency (50-90 rpm)
• Mass recovery analysis for each layer
• Envelope densitydeterminationED = Mass / [V solid + Vpores]
LEPECHUKA (2013)
0
20
40
60
80
100
2,100 2,200 2,300 2,400 2,500 2,600 2,700
Mas
sa a
cum
ula
da
(%)
Massa específica aparente - média Geopyc (g/cm³)
J1 J2
J3 J4
J5 J6
J7 J8
Results(Density separation)
With fines
Without fines
Pressure – 0,01 barFrequency – 50 rpm
LEPECHUKA (2013)
Experimental Planning
• Characterization of aggregates
– Particle Size Distribution and shape analysis
– Porosity (mercury intrusion)
– Density and water absorption (std methods)
Dynamic Image Analysis
Results
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10
20
30
40
50
60
70
80
90
100
0,4 0,5 0,6 0,7 0,8 0,9 1
Dis
trib
uiçã
o vo
lum
étri
ca a
cum
ulad
a (%
)
Esfericidade
densa
leve
mista
areia de cava
areia de brita
areia de calcário
pó de pedra
pedrisco
0
10
20
30
40
50
60
70
80
90
100
0,3 0,5 0,7 0,9
Dis
trib
uiçã
o vo
lum
étri
ca a
cum
ulad
a (%
)
Relação de aspecto
densa
leve
mista
areia de cava
areia de brita
areia de calcário
pó de pedra
pedrisco
Results
Agregados Absorção de água
(% kg/kg)
Massa Específica Aparente (MEA)
(kg/dm³)
Massa Específica Real (MER) (kg/dm³)
Porosidade [(1–MEA/MER)x100]
(%)
Areia densa de RCD
5,99 ± 0,06 2,37 ± 0,01 2,67 ± 0,01 11,2
Areia leve de RCD
10,28 ± 1,25 2,07 ± 0,02 2,63 ± 0,13 21,3
Areia mista de RCD
9,72 ± 0,45 2,02 ± 0,02 2,52 ± 0,01 19,8
Areia cava 0,34 ± 0,11 2,62 ± 0,01 2,65 ± 0,01 1,1Pó de pedra 1,08 ± 0,04 2,59 ± 0,01 2,66 ± 0,01 2,6Pedrisco fino 0,97 ± 0,01 2,61 ± 0,01 2,67 ± 0,01 2,2
Experimental Planning
Concreto seco com areia mista de RCD (CS-AM)
Material Traço Massa (%) Volume (%)
Cimento (CP V 40) 1,00 16,67 11,53
Areia mista de RCD 5,00 83,33 88,47
Total 6,00 100,00 100,00
Concreto seco com areia densa e leve de RCD (CS-AD&L)
Material Traço Massa (%) Volume (%)
Cimento (CP V 40) 1,00 15,38 11,51
Areia leve de RCD 2,50 38,46 43,11
Areia densa de RCD 3,00 46,15 45,38
Total 6,50 100,00 100,00
Concreto seco de referência, com agregado natural (CSR-AN)
Material Traço Massa (%) Volume (%)
Cimento (CP V 40) 1,00 13,33 11,66
Areia cava 0,65 8,67 8,86
Pó de pedra 1,30 17,33 17,66
Pedrisco 4,55 60,67 61,82
Total 7,50 100,00 100,00
Particle size distribution of dry mixes
0%
2%
4%
6%
8%
10%
12%
14%
1 10 100 1.000 10.000 100.000
Vo
lum
e r
eti
do
(%
cm
³/cm
³)
Abertura da malha (µm)
mistura cimento:agregados naturais
mistura cimento:areia densa e leve de RCD
mistura cimento:areia de RCD misto
Results
2,33
2,342,33
2,08
2,13
2,08
2,09
1,97
2,04
1,961,96
2,00
1,90
1,95
2,00
2,05
2,10
2,15
2,20
2,25
2,30
2,35
2,40
5 6 7 8 9 10
Ma
ssa
esp
ecí
fica
do
co
ncr
eto
(K
g/d
m³)
Umidade (%)
CSR-AN
CS-AD&L
CS-AM
Results
0
10.000
20.000
30.000
40.000
50.000
60.000
70.000
80.000
90.000
100.000
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94
Car
ga (N
)
Deslocamento do pistão (mm)
CS-AM
CS-AD&L
CRS-AN
Results
0
5
10
15
20
25
30
35
40
45
50
CS-AM Cs-AD&L CSR-NA
Po
rosi
ty (
% d
m³/
dm
³)
Pores -before compaction Pores - after compaction
Results
0
5
10
15
20
25
CS-AM CS-AD&L CSR-AN
Re
sist
ên
cia
à C
om
pre
ssão
(M
Pa)
média 3 dias
média 7 dias
média 28 dias
Experimental Planning
0
2
4
6
8
1 10 100 1000 10000
Dis
trib
uiç
ão v
olu
mét
rica
(%
)
Tamanho da partícula (mm)
CONT-M
0
2
4
6
8
1 10 100 1000 10000
Dis
trib
uiç
ão v
olu
mé
tric
a (%
)
Tamanho da partícula (mm)
DESC-M
REF
0
2
4
6
8
10
1 10 100 1000 10000
Dis
trib
uiç
ão v
olu
mét
rica
(%
)
Tamanho da partícula (mm)
DESC-LD
Conclusions
• Reduction of CDW recycled aggregate porosity and gap-graded particle size distribution improve dry cast concrete performance.
• A sieving CDW recycling plant has lower environmental impact and it is a cheaper solution, being a more ecofficient CDW recycling solution.
• Lab tests can be used to understand behaviourduring compaction.
Bibliography
• QUATTRONE, MARCO ; ANGULO, SERGIO C. ; JOHN, VANDERLEY M. . Energy and CO2 from high performance recycled aggregate production. Resources, Conservation and Recycling, v. 90, p. 21-33, 2014.
• SILVA, R. B. ; ANGULO, S. C. ; PILEGGI, R. G. ; SILVA, C. O. . Concretos secos produzidos com agregados reciclados de RCD separados por densidade. Artigo em revisão. Revista AmbienteConstruido. 2014.
• Nakano,AY.;Torres,DR.; Grandes,FA.; Maia, FT;Fujitaki, GJ. Estudo da viabilidade do uso de resíduosda construção e demolição na fabricação de peças intertravadas de concreto. 2014. Trabalho de Conclusão de Curso (Graduação em Engenharia Civil) - Universidade de São Paulo.
• ULSEN, C. ; KAHN, H. ; HAWLITSCHEK, G. ; MASINI, E.A. ; ANGULO, S.C. ; JOHN, V.M. . Production of recycled sand from construction and demolition waste. Construction & Building Materials, v. 40, p. 1168-1173, 2013.
• ANGULO, S. C. ; JOHN, V. M. ; ULSEN, C. ; KAHN, H. ; MUELLER, A. . Separação óptica do material cerâmico dos agregados mistos de resíduos de construção e demolição. Ambiente Construído (Online), v. 13, p. 61-73, 2013.
• LEPECHUKA, V. O. PRODUÇÃO DE AGREGADOS GRAÚDOS RECICLADOS DE BAIXA POROSIDADE EM JIGUE DE ESTRATIFICAÇÃO LABORATORIAL. Trabalho de Conclusão de Curso. 2013.
• DAMINELI, B. L. KEMEID, F. M. AGUIAR, P. S.; JOHN, VANDERLEY M. Measuring the eco-efficiency ofcement use. Cement and Concrete Composites, v. 32, n. 8, p. 555-562, 2010.
• ANGULO, S. C.; MUELLER, A. . Determination of construction and demolition recycled aggregates composition, in considering their heterogeneity. Materials and Structures, v. 42, p. 739-748, 2009.