CDW RECYCLED AGGREGATES FOR DRY CAST CONCRETES

Sérgio Angulo

sergio.angulo@lme.pcc.usp.br

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

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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

http://dx.doi.org/10.1590/S1678-86212013000200006

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.

WAYS TO IMPROVE CDW RECYCLED AGGREGATES

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)

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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)

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sa a

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(%)

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

• Lab test CDW recycling routes

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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trib

uiçã

o vo

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étri

ca a

cum

ulad

a (%

)

Esfericidade

densa

leve

mista

areia de cava

areia de brita

areia de calcário

pó de pedra

pedrisco

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trib

uiçã

o vo

lum

étri

ca a

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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

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Vo

lum

e r

eti

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(%

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

Compression of Mixes(force and displacement)

Results

2,33

2,342,33

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2,13

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1,97

2,04

1,961,96

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ssa

esp

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fica

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ncr

eto

(K

g/d

m³)

Umidade (%)

CSR-AN

CS-AD&L

CS-AM

Results

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Car

ga (N

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Deslocamento do pistão (mm)

CS-AM

CS-AD&L

CRS-AN

Results

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CS-AM Cs-AD&L CSR-NA

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Pores -before compaction Pores - after compaction

Results

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CS-AM CS-AD&L CSR-AN

Re

sist

ên

cia

à C

om

pre

ssão

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média 3 dias

média 7 dias

média 28 dias

Experimental Planning

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CONT-M

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DESC-M

REF

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DESC-LD

Experimental Planning

Results

Results

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.