DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
INFLUENCE OF CURING CONDITIONS ON THE DURABILITY-RELATED PERFORMANCE OF CONCRETE WITH SELECTED
PLASTIC WASTE AGGREGATES
Authors:
Rui Vasco Silva; Jorge de Brito; Nabajyoti Saikia
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
Table of contents• Introduction
• Objectives
• State of the art
• Experimental Campaign– Aggregate tests
– Concrete mixes
– Fresh concrete tests
– Curing conditions
– Hardened concrete tests
• Discussion of the results– Aggregates
– Fresh concrete
– Hardened concrete• Shrinkage
• Water absorption by immersion
• Water absortion by capillarity
• Carbonation
• Chloride ion penetration
• Conclusions
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IntroductionWhat is “Sustainability”?
• The original definition of “sustainable development”, in the Bruntland report(World Commission on Environment and Development, 1987), described itas the following:
“Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs”
Environment
Social Economic
Sustainable development
Equitable
Bearable Viable
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
Plastic
• Plastic is globally used as raw material for the production of severalpacking products, most electric and household appliances, toys, aswell as in the automobile industry, civil construction and textile sector;
• In 2007, ECOPET stated that the World’s annual plastic consumptionof polyethylene terephthalate was about 10 million tons, whichrepresents 250 billion plastic bottles.
Introduction
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Objectives
• Assess the effect of the curing conditions on thedurability-related performance of concrete with selectedplastic waste aggregates (CPA);
• evaluate the variation of CPA’s performance with thereplacement ratio of natural aggregates (NA) by plasticaggregates (PA) with different shapes and sizes;
• increase the knowlegde on the use of plastic aggregatesin concrete manufacture.
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
• Literature review (scientific publications, masters and douctorate theses, conference proceedings, etc.)
• Experimental campaigns associated with the use of plastic aggregates on the durability-related performance of concrete:
Akçaözoglu et al. Frigione Albano et al. Choi et al. Ismail and Al-Hashmi Fraj et al. Kou et al.
• Experimental campaigns associated with the influence of curing conditions on the durability-related performance of concrete:
Güneyisi et al. Lo and Lee Amorim Türkmen e Kantarci Toutanji e Bayasi Safiuddin et al.
State of the art
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• Akçaözoglu et al. (2009) and Frigione (2010) obtained greater shrinkagevalues for concrete specimens with PET aggregates, when compared withthe control concrete;
• Kou et al. (2009) and Souroushian (1999) observed that the dryingshrinkage values decreased as the amount of plastic aggregates in themix increased, since the introduction of plastic flakes could control theconcrete’s shrinkage cracks;
• Akçaözoglu et al. (2009), Albano et al. (2009) and Choi et al. (2009)demonstrated that the water absorption values of concrete with plasticaggregates are greater than those of the control concrete;
• Akçaözoglu et al. (2009) and Kou et al. (2009) obtained greater resistanceto carbonation and chloride ion penetration with the plastic aggregatesin the mix.
State of the art
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
• Every author whose experimental campaigns were associated withthe influence of curing conditions on the durability-relatedperformance of concrete, obtained similar results. They haveconcluded that concrete specimens cured in environments with highrelative humidity had better performances than those cured in drierconditions. All of these properties were studied in this experimentalinvestigation (shrinkage, water absorption by immersion and bycapillarity, carbonation and chloride ion penetration).
State of the art
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Unibetão Selenis
Experimental campaign
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
• Aggregates’ tests:
Grading analysis NP EN 933-1 (2000) and NP EN 933-2 (1999)Density and water absorption NP EN 1097-6 (2003)Bulk density NP EN 1097-3 (2003)"Los Angeles“ abrasion LNEC E-237 (1970)Shape index NP EN 933-4 (2002)
Experimental campaign
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Experimental campaign
• Concrete mixes:
RC reference concrete
C7.5PC concrete with replacement ratio of 7.5% of coarse natural aggregates with PC aggregates
C7.5PP concrete with replacement ratio of 7.5% of fine natural aggregates with PP aggregates
C15PP concrete with replacement ratio of 15% of fine natural aggregates with PP aggregates
C7.5PF concrete with replacement ratio of 7.5% of fine natural aggregates with PF aggregates
C15PF concrete with replacement ratio of 15% of fine natural aggregates with PF aggregates
PC – coarse flakes plastic aggregates
PP – pellets plastic aggregates
PF – fine flakes plastic aggregates
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
• Fresh concrete tests:
Slump NP EN 12350-2 (2002)
Fresh density NP EN 12350-6 (2002)
Experimental campaign
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• Curing conditionsOutdoor environment
Laboratory environment
Wet chamber
Temperature and relative humidity reading equipment
Experimental campaign
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• Hardened concrete tests:
Drying shrinkage LNEC E-398 (1993)Water absorption by immersion LNEC E-394 (1993)Water absorption by capillarity LNEC E-393 (1993)Carbonation LNEC E-391 (1993)Chloride ion penetration Nordtest NT Build 492 (2004)
Experimental campaign
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Shrinkage 2 specimensWater absorption by immersion 4 specimensWater absorption by capillarity 4 specimensCarbonation 8 specimensChloride ion penetration 6 specimens
• Total duration of this experimental investigation: 14 months
Experimental campaign
0
50
100
150
200
250
300
350
400
450
Dryingshrinkage
Waterabsorption
byimmersion
Waterabsorption
by capillarity
Carbonation Chloride ionpenetration
Total
Specimens 36 72 72 144 108 432
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Discussion of the results• Aggregates
Aggregate Fine sand Coarse sand “Rice grain” Gravel 1 Gravel 2 PC PP PF
Dry density (kg/m3) 2647 2717 2732 2665 2671 1302 1303 1280
Water absorption (%) 0.15 0.05 0.31 0.92 0.55 0.75 0.39 0.11
Bulk density (kg/dm3) 1462 1461 1469 1420 1394 261 739 438
LA abrasion (%) - - - 29.3 32.0 - - -
Shape index (%) - - - 16.2 11.0 - - -
• The PA’s density is about half of that obtained for the NA;
• the PC aggregates obtained the lowest bulk density of all plastic aggregates while
that of the PP aggregates was the highest;
• a visual analysis performed on the plastic aggregates revealed that the PC and PF
aggregates were flaky and non-uniform, while the PP aggregates were round-
shaped and uniform.
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• Fresh concrete testsMix W/C
RC 0,54
C7,5PC 0,61
C7,5PP 0,53
C15PP 0,52
C7,5PF 0,56
C15PF 0,61
y = -19,573x + 2361,8
y = -9,2567x + 2364,6R² = 0,9949
y = -18,17x + 2365,2R² = 0,9981
2050
2100
2150
2200
2250
2300
2350
2400
0 3 6 9 12 15 18
Den
sity
(kg
/m3 )
Replacement ratio (%)
BPC BPP BPF
Slump
Fresh density
• For the same target slump, the W/C ratio varies
according with the PA type and replacement ratio;
• the fresh concrete density decreases with
increasing amount of PA.
Discussion of the results
Outdoor environmentLaboratory environment
Wet chamber0
50
100
150 130 150
120 127 137134
139
120 134127
124 145
115 140138
140140 145
Outdoor environment Laboratory environment Wet chamber
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• Hardened concrete tests – Drying shrinkage
• Concrete specimens cured in the wet chamber
presented more stable and less shrinkage
values, than in any other curing condition;
• All CPA presented less shrinkage values when
cured in progressively drier environments,
when compared to the RC.
Wet chamberLaboratory environmentOutdoor environment
Discussion of the results
0,00E+00
1,00E‐04
2,00E‐04
3,00E‐04
4,00E‐04
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (m/m
)
Time (days)
RC C7,5PC C7,5PP
C15PP C7,5PF C15PF
‐1,00E‐04
0,00E+00
1,00E‐04
2,00E‐04
3,00E‐04
4,00E‐04
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (m/m
)
Time (days)
RC C7,5PC C7,5PP
C15PP C7,5PF C15PF
‐5,00E‐05
5,00E‐05
1,50E‐04
2,50E‐04
3,50E‐04
Wet chamber Outdoorenvironment
Laboratoryenvironment
Shrinkage at 91 days (m
/m)
RC C7,5PC C7,5PP C15PP C7,5PF C15PF
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• Haredened concrete tests – Water absorption by immersion
• Water absorption was higher in concrete specimens
cured in the laboratory environment, where the
relative humidity was lower;
• this test did not allow to fully analyze the influence
of curing conditions among the various types of
concrete or whether its influence is negligible.
Discussion of the results
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
16,0
18,0
RC C7,5PC C7,5PP C15PP C7,5PF C15PF
Wat
er a
bsor
ptio
n by
imm
ersi
on (%
)
Outdoor environment Laboratory environment Wet chamber
12,00
12,50
13,00
13,50
14,00
14,50
15,00
15,50
16,00
16,50
17,00
Wet chamber Outdoor environment Laboratory environment
Wat
er a
bsor
ptio
n by
imm
ersi
on (%
)
RC C7,5PC C7,5PP C15PP C7,5PF C15PF
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• Hardened concrete tests – Water absorption by capillarity
• Generally, water absorption by capillarity values was higher
in CPA, than that obtained in the RC;
• CPA with coarse PA had higher water absorptions values
than those obtained for the concrete with fine PA, for the
same replacement ratio;
• although all concrete specimens present higher absorptions
when cured in progressively drier environments, the RC had
a higher slope than the rest of the mix designs.
Cement paste
SandPET
Cement paste
Discussion of the results
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
RC C7,5PC C7,5PP C15PP C7,5PF C15PF
Wat
er a
bsor
ptio
n by
cap
illar
ity a
t 72
hour
s (g
/mm
2x
10-3
)
Outdoor environment Laboratory environment Wet chamber
0,00
2,00
4,00
6,00
8,00
10,00
12,00
14,00
16,00
18,00
Wet chamber Outdoor environment Laboratory environment
Wat
er a
bsor
ptio
n by
cap
illar
ity a
t 72
hour
s (g
/mm
2x
10-3
)
RC C7.5PC C7.5PP C15PP C7.5PF C15PF
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• Hardened concrete tests - Carbonation
• The carbonation depths increased with the
increasing replacement ratio of NA with PA;
• concrete specimens cured in drier environments
presented higher carbonation depths;
• there was little or no influence of the curing
conditions between the CPA and the RC.
Discussion of the results
0
5
10
15
20
25
30
35
40
45
RC C7,5PC C7,5PP C15PP C7,5PF C15PF
Car
bona
tion
dept
h at
91
days
(m
m)
Outdoor environment Laboratory environment Wet chamber
0,00
5,00
10,00
15,00
20,00
25,00
30,00
35,00
40,00
Wet chamber Outdoor environment Laboratory environment
Car
bona
tion
dept
h at
91
days
(m
m)
RC C7.5PC C7.5PP C15PP C7.5PF C15PF
DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012
Discussion of the results• Hardened concrete tests – Chloride ion penetration
• The chloride ion migration increases with the
replacement ratio of NA with PA;
• concrete specimens cured in wetter environments
have shown lower values for chloride ion penetration;
• all concrete mix designs showed similar trends, for
the chloride ion penetration, when cured in
progressively drier environments.
0
5
10
15
20
25
30
35
40
45
RC C7,5PC C7,5PP C15PP C7,5PF C15PF
Chl
orid
e io
n di
ffus
ion
at 9
1 da
ys (
x10-2
m2 /
s)
Outdoor environment Laboratory environment Wet chamber
5,00
10,00
15,00
20,00
25,00
30,00
35,00
40,00
Wet chamber Outdoor environment Laboratory environment
Chl
orid
e io
n di
ffus
ion
at 9
1 da
ys
(x10
-2m
2 /s)
RC C7.5PC C7.5PP C15PP C7.5PF C15PF
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• In Portugal, the research on the use of PET in mortars and concrete is almost nonexistent;
• internationally, few experimental researches studied the durability-related performanceof CPA were found;
• after a thorough literature review, it was concluded that there were no studies thatassessed the influence of curing conditions on the durability-related performance ofconcrete with selected plastic-waste aggregates;
• slump was influenced by the shape of the replaced particles. When PC and PFaggregates, which presented higher shape indexes, were introduced in concrete, thew/c ratio had to be increased in order to maintain the slump. The opposite occurred inthe case of concrete mixes with PP aggregates;
• there was a decrease in fresh density with the increasing amount of PA in the mix.There was a decrease of 11,5% for a replacement ratio of 15%;
Conclusions
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Conclusions• except for the C7,5PC and C15PP mixes, cured in the outdoor environment and wet
chamber, all CPA showed lower drying shrinkage values than those obtained by theRC specimens. It was also observed that CPA had lower shrinkage when cured inprogressively drier environments;
• the water absorption by immersion increases with the replacement ratio of NA by PA.However, this test did not allow to analyze effectively the difference of the influenceof curing conditions between the CPA and the RC;
• water absorption by capillarity was generally greater in CPA, when compared with the
RC. However, the RC presented a higher increment, in this property, when cured in
progressively drier environments;
• the introduction of PA into the mix led to greater carbonation depth and the coarser
and more irregular the shape, the greater the carbonation depth was. All concrete
specimens presented similar trends when cured in progressively drier environments.
Therefore, there was no difference in the influence of curing conditions between the
CPA and the RC;
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Conclusions
• a lower resistance to chloride ion penetration can be obtained for higher replacement
ratios of NA for PA. For the same replacement ratio (7,5%), concrete with fine flaky
PA (PF) had a higher chloride ion penetration than concrete specimens with coarse
flaky PA (PC). No differences of the influence of curing conditions between the CPA
and the RC were found, as all concrete mix designs presented similar trends when
cured in progressively drier environments;
• although the durability-related performance of CPA was poorer than that of the
conventional concrete, the use of PA in concrete manufacture may have several
useful applications, where some relevant properties can be improved by adding these
materials.
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