LNECdurati.lnec.pt/pdf/ICDS12_Presentations/E_3_JBrito.pdf · durable structures lnec lisbon 31 may - 1june 2012 influence of curing conditions on the durability- related performance

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


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

ICDS12 International Conference DURABLE STRUCTURES: from construction to rehabilitation LNEC • Lisbon • Portugal • 31 May - 1 June 2012

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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


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.


• 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


• 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


• 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)



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• 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


• Fresh concrete tests:

Slump NP EN 12350-2 (2002)

Fresh density NP EN 12350-6 (2002)



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• Curing conditionsOutdoor environment

Laboratory environment

Wet chamber

Temperature and relative humidity reading equipment



• 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)



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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


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


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


• 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


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.


0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

16,0

18,0


Wat

er a

bsor

ptio

n by

imm

ersi

on (%

)


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 (%

)



• 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


0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0


Wat

er a

bsor

ptio

n by

cap

illar

ity a

t 72

hour

s (g

/mm

2x

10-3

)


0,00

2,00

4,00

6,00

8,00

10,00

12,00

14,00

16,00

18,00


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.


0

5

10

15

20

25

30

35

40

45


Car

bona

tion

dept

h at

91

days

(m

m)


0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00


Car

bona

tion

dept

h at

91

days

(m

m)



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


Chl

orid

e io

n di

ffus

ion

at 9

1 da

ys (

x10-2

m2 /

s)


5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00


Chl

orid

e io

n di

ffus

ion

at 9

1 da

ys

(x10

-2m

2 /s)



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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


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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LNECdurati.lnec.pt/pdf/ICDS12_Presentations/E_3_JBrito.pdf · durable structures lnec lisbon 31 may - 1june 2012 influence of curing conditions on the durability- related performance