Construction and Building Materials 25 (2011) 1049–1055

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Construction and Building Materials

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Use of waste polymers in concrete for repair of dam hydraulic surfaces

José Carlos Alves Galvão a,*, Kleber Franke Portella a, Alex Joukoski a, Roberto Mendes a,Elizeu Santos Ferreira b

a Centro Politécnico da UFPR, Caixa Postal 19067, CEP 81531-980, Jardim das Américas, Curitiba, Paraná, Brazilb Rua Izidoro Biazetto, 158, CEP 81200-240, Mossunguê, Curitiba, Paraná, Brazil

a r t i c l e i n f o a b s t r a c t

Article history:Received 6 February 2010Received in revised form 21 May 2010Accepted 19 June 2010Available online 23 July 2010

Keywords:ConcreteRepair materialsWaste polymersRecycling

0950-0618/$ - see front matter � 2010 Elsevier Ltd. Adoi:10.1016/j.conbuildmat.2010.06.073

* Corresponding author. Tel.: +55 41 33616304; faxE-mail address: galvao@utfpr.edu.br (J.C.A. Galvão

The durability of a concrete structure is strongly influenced by the inadequate use of materials and by thephysical and chemical effects of the environment of its immersion. The immediate consequence is theanticipated necessity of maintenance and repairs, which must have specific characteristics, mainlymechanical and chemical, based on the material of the base or its substratum. In this study differentrepair materials (RM’s) were analyzed and manufactured to be used on concrete hydraulic surfaces ofhydroelectric power plant dams that suffered different types of damage, such as erosion–abrasion andchemical attacks from the reservoir water. Concrete samples were made from polymeric and elastomermaterials proceeding from the recycling industry, such as agglutinated low-density polyethylene (LDPE),crushed polyethylene terephthalate (PET) and rubber from useless tires. The contents of each materialwere 0.5%, 1.0%, 2.5%, 5.0% and 7.5%. Their properties were compared with a reference concrete, withoutany additions, comparing the compression strength, tensile strength under diametrical compression,underwater erosion–abrasion resistance, microstructure and field application. The samples with 2.5%of addition were the most effective, being LDPE the one which presented better performance.

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1. Introduction

The addition of polymeric waste to concrete corresponds to anew perspective in research activities, integrating the areas of con-crete technology and environmental technology.

Industrial and domestic waste have a significant percentage ofpolymeric materials in its constitution, which occupies a consider-able volume on landfills. Therefore its recycling is interesting to re-search and development of technologies for minimizing theproblems caused by this waste.

Polypropylene (PP) [14], polyethylene (PE) [27] and nylon [25],besides other materials [24,17] are examples of polymeric addi-tions to concrete, mainly in the fiber shape, providing the rein-forcement of concrete structures, known as ‘‘fiber-reinforcedconcrete” (FRC).

Depending on the appropriate final target, varied types of wastecan be used in concrete: Portella et al. [19] and Guerra et al. [6]have studied the properties of concrete with addition of ceramicwaste; Ismail and Al-Hashmi [10] have studied concrete with recy-cled plastic addition; Angulo et al. [3] have characterized recycledmaterials from construction and demolition as an aggregate forconcrete; and, amongst others, Hoppen et al. [7] have found in con-

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crete the possibility to deposit the residual sludge from watertreatment stations.

Different works, as of Rebeiz [22], Choi et al. [5] and JO et al.[11], have analyzed the effect of addition of recycled PET to theproperties of concrete. The fibers of recycled PET easily mix inthe concrete, giving new properties to the material [16]. Khalooet al. [12] have observed that the addition of tire rubber particlesprovided the concrete with higher ductility in compressivestrength testing, if compared with concrete without addition.One of the advantages of the use of recycled plastic in concrete isthe reduction of solid waste in landfills [23].

The concrete with addition of polymeric materials, as well asthe FRC, has had a widespread increase in its application, whichcan also be seen in Brazil. An appreciable improvement of perfor-mance related to the control of fissures of plastic retraction wasobserved for mortars applied in repair, where the low modulusof elasticity from fibers was enough to inhibit the propagation ofcracks. Due to this redistribution of tension, the stored elastic en-ergy was not dissipated through a single source of propagation,but, possibly, through several microscopic cracks. The length ofeach one of those cracks, as well as the loss of resistance, was smal-ler than the one caused by a single crack, even for the same consid-ered superficial area [18].

The hydraulic surfaces of concrete barrages are exposed toerosive wearing [1] and to cracks caused by the pressure ofcrystallized salts in pores [26] and by the exposition to aggressive

Table 2Results of chemical analysis of the cement CPII-Z 32.

Component Abbreviation % (weight) Standards limits (%)

Lime CaO 52.68 –Silica SiO2 22.54 –Alumina Al2O3 6.80 –Iron oxide Fe2O3 3.22 –Sulfite SO3 2.77 64.0Magnesia MgO 6.13 66.5Loss on ignition L.O.I. 3.25 66.5Insoluble residue I.R. 8.88 616

Table 3Results of the coarse aggregate tests.

Properties Values

Specific gravity (dry) 2.88 g/cm3

Specific gravity (SSS) 2.93 g/cm3

Grain size distribution 4.75–12.5 mm

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agents [9], causing pathologies and requiring frequent mainte-nance, including the need for periodical repairs. Because of that,it is necessary to use a RM that presents properties compatiblewith the ones of the base material, such as the coefficient of ther-mal dilatation, the mechanical resistance, as well as good adher-ence between both. In the case of concrete hydraulic surfaces,properties as impact resistance, erosion–abrasion and durabilityare extremely desirable. Horszczaruk [8] has studied the erosion–abrasion resistance of different kinds of high resistance concretein hydraulic structures and observed, among other characteristics,that the use of polyvinyl chloride (PVC) fibers has improved theconcrete resistance to underwater erosion–abrasion.

The present work focused on the search of a feasible solution forthe recovery of concrete surfaces of hydraulic structures of hydro-electric power plant dams, its use and, in turn, the reduction ofenvironmental problems caused by the amount of polymeric wastein landfills and in the environment in general.

Maximum dimension 9.5 mmModule of fineness 5.64Powder material content 1.3%Organic material content 0.1%Water absorption 2.0%

Table 4Properties of the fine aggregate.

Properties Values

2. Materials and methods

2.1. Materials

2.1.1. CementThe cement used was the Portland cement with pozzolan (CPII-Z 32), which was

characterized by physical–chemical techniques, according to recommendationsfrom the standards and regulations of ABNT, which is the Brazilian standardizationcommittee. In Tables 1 and 2, the physical and chemical characteristics of the ce-ment are presented, respectively.

Specific gravity 2.61 g/cm3

Module of fineness 2.22Powder material content 0.3%Organic material content 0.2%Water absorption 0.2%

2.1.2. Coarse aggregateCrushed basaltic rocks were used as coarse aggregate, with a maximum dimen-

sion of 9.5 mm. In Table 3, the properties of the aggregate are presented.

Table 5Properties of the recycled materials.

2.1.3. Fine aggregateNatural washed sand was used in the making of the concrete. The properties of

the fine aggregate are listed in Table 4.

Property Material

LDPE PET TIRE

Density (kg/m3) 860 1320 660Absorption (%) 7.4 3.9 2.1

Table 6Sieve analysis of the polymeric waste and sand.

Sieve Cumulative retained (%)

Number Size (mm) PET LDPE TIRE Sand

1/2 inch 12.5 4 0 0 03/8 inch 9.5 19 0 0 0

2.1.4. Polymeric wasteTwo polymers from the plastic recycling industry were used: LDPE and PET. The

agglutinated LDPE was resultant from the processing of plastic packs (bags of gar-bage and plastic bags). In the recycling industry this material was selected, sepa-rated, washed, crushed and agglutinated by mechanical process at anapproximate temperature of 60 �C. The PET came from liquid deodorant flasks. Afterthe selective collection, the material went through the process of separation, havingbeen previously washed and crushed.

In complement to this work, vulcanized natural rubber fibers (elastomer) werealso applied, gathered from the treads of useless tires from the recycling industry.

The polymeric waste was characterized in agreement to Mercosul standards,NBR NM numbers 30/01, 52/02 and 53/02. The properties of the polymeric wasteare presented in Table 5. The sieve analysis of the polymeric waste and sand arepresented in Table 6.

1/4 inch 6.3 46 0 0 04 4.8 62 2 0 08 2.4 92 24 1 316 1.2 96 73 14 1330 0.6 100 93 41 3650 0.3 100 99 84 72100 0.15 100 100 98 98

2.2. Mixture proportion

To optimize the mixture of each one of the constituent materials of the con-crete, mixing studies were made, verifying the workability and, later, the axial com-pressive strength. The idealized composition, considering a slump stipulated at(30 ± 10) mm, was of 1:1. 93:3. 07:0. 45 (c:s:g:w/c), with a cement consumptionof 389 kg/m3. This mixture was considered the reference concrete (RC), with theelastomer and the polymeric waste being added in different contents.

In order to keep the water/cement ratio (w/c) and the slump stable, a plasticiz-ing additive was used, based on the works of Siddique et al. [23].

Table 1Results of physical tests in cement CPII-Z 32.

Properties Values

Fineness 3440 cm2/gInitial setting time 5 h:10 minFinal setting time 6 h:10 minDensity 2.97 g/cm3

Contents of 0.5%, 1.0%, 2.5%, 5.0% and 7.5% of TIRE, PET and LDPE, in weight,were added to the RC mixture, in partial replacement of the fine aggregate. In Ta-ble 7, the resultant compositions are presented.

The polymeric wastes have lower specific gravity than the sand (Tables 5 and 6).This resulted in a greater volume of recycled material in admixture of concretecausing less workability and requiring addition of plasticizer in order to keep thestipulated slump, but the water–cement ratio was always invariable at 0.45 (Table 7).

2.3. Compressive strength and tensile strength under diametrical compression tests

The compressive strength test and tensile strength under diametrical compres-sion test were carried in agreement to the standards NBR 5739/07 and NBR 7222/94, respectively. The three polymeric waste products, TIRE, PET and LDPE, were

Table 7Mixtures of concrete with addition of polymeric waste.

Material Cement(kg/m3)

Coarseaggregate(kg/m3)

Sand(kg/m3)

Polymericwaste(kg/m3)

Polymericwaste (%)

Admixtureplasticizer(% cement)

RC 389 1193 750.00 – – –TIRE0.5 389 1193 746.25 3.75 0.50 –TIRE1 389 1193 742.50 7.50 1.00 0.20TIRE2.5 389 1193 731.25 18.75 2.50 0.20TIRE5 389 1193 712.50 37.50 5.00 0.30TIRE7.5 389 1193 693.75 56.25 7.50 0.40PET0.5 389 1193 746.25 3.75 0.50 –PET1 389 1193 742.50 7.50 1.00 –PET2.5 389 1193 731.25 18.75 2.50 –PET5 389 1193 712.50 37.50 5.00 0.20PET7.5 389 1193 693.75 56.25 7.50 0.30LDPE0.5 389 1193 746.25 3.75 0.50 0.20LDPE1 389 1193 742.50 7.50 1.00 0.20LDPE2.5 389 1193 731.25 18.75 2.50 0.20LDPE5 389 1193 712.50 37.50 5.00 0.40LDPE7.5 389 1193 693.75 56.25 7.50 0.50

Fig. 1. (a) View of the spillway; (b) detail of the displacement of the covering andcarbonation layers.

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tested in all studied contents: 0.5%, 1.0%, 2.5%, 5.0% and 7.5% (percentage in weight)in substitution of the fine aggregate. Those concrete samples were compared withthe RC. The evolution of the resistance was followed by testing at the ages of 7, 14and 28 days, with two specimens for each age.

In tensile strength under diametrical compression testing, two specimens wereanalyzed, at the age of 28 days, for each studied mixture.

2.4. Underwater erosion–abrasion resistance

For the analysis of erosion–abrasion resistance using the underwater method,ASTM C 1138/97 standard was followed. Cylindrical concrete samples with diame-ter of 300 mm and height of 100 mm were cast. After 28 days of curing in a humidchamber, with a relative humidity higher than 95% and controlled temperature of(23 ± 2) �C, the underwater erosion–abrasion resistance of the concrete was evalu-ated in contents of 2.5% and 5.0% (percentage in weight), for the three studied mate-rials. The RC was also evaluated.

2.5. Accelerated aging in SO2 chamber and SEM microstructure investigation

To test the durability of the developed mixture, prismatic reinforced concretesamples were manufactured, within the dimensions of (71 � 100 � 25) mm.

Those samples were aged for 180 days in a humid climatic chamber, having SO2

at 0.67% (in volume) and internal temperature of (40 ± 3) �C (ASTM 87/07-Method A– Continuous Exposition) [2].

After this period, these samples were manually broken and its surfaces analyzedby Scanning Electron Microscopy (SEM), in Philips equipment, model XL30,equipped with Energy Dispersive Spectroscopy (EDS).

2.6. Field application

For the field application, the dosages with 2.5% and 5% of addition in weightwere selected, from TIRE, LDPE and PET, as well as the RC, to be applied in the spill-way surface of Mourão Hydroelectric Power Plant dam, located in the city of CampoMourão, in the State of Paraná, Southern Brazil.

The points of application of the RM’s were selected in the spillway after a com-plete observation of the state of its conservation and of the localization of defectsdisplayed in the concrete blocks, as illustrated in Fig. 1.

Initially, points that presented superficial defect and/or signals of previous re-pairs were identified, with its areas being delimited. The dimension was of(750 � 750) mm, which became the standard area determined for the applicationof RM’s. In the points where the extension of the pathology exceeded 750 mm, rect-angular repairs were done, maintaining the repaired areas constant. Thus, a com-parative standard of performance for each type of employed material was obtained.

The places were cut in the lines that limited the selected areas, thus determin-ing the area of the repairs. A process of humid cut was done with the use of a sawcontaining a special diamond disc.

After the cutting process, the scarification process was made with an electrome-chanical hammer. In this procedure three pieces of equipment with differentstrength and gauge were used. The heavier pieces of equipment were used forthe initial work and removal of degraded material until finding a surface withoutdefects or voids in the concrete.

The mixtures of concrete in field followed the same procedure used in the lab-oratory for concrete with polymeric waste.

The cleaning of the points of application of the RM’s was executed with waterspurts, removing all the dust and small fragments of removed material.

Preliminary studies of the adhesion resistance of the RM’s to the samples ex-tracted from the dam have indicated the need of applying a tack bridge on thedry substratum surface. For that, a high viscosity Epoxy resin was used as structuraladhesive to the resin base. The necessity of this type of tack bridge was evidencedby studies carried out at laboratory.

The RM was put on the substratum with a trowel, being compacted with pylon,in order to improve the contact and remove the confined air bubbles.

The final superficial finishing was made with a metallic plate, which gave to thefinished surface a smoothened aspect.

Applications of RM in a total of seven distinct points were made, analyzing theRC, as well as the recycled and elastomer materials, according to the mixtures stud-ied in laboratory (Table 6). Those repair areas had their performance analyzedthroughout the time, in terms of its compatibility with the substratum and of theexistence of edge effect and other defects.

3. Results and discussion

3.1. Compressive strength

The curves of the resistances of the axial compression of theRMs studied (LDPE, PET and TIRE) and the CR, in terms of the cur-ing age, are presented in the graphs of Figs. 2–4, respectively. Forthe three different studied materials and its respective contentsit was evidenced that the results obtained in the assays of com-pressive strength in terms of curing were inversely proportionalto the contents of recycled fiber addition. This trend was also no-ticed by Choi et al. [5] when they studied the effects of the additionof residues from PET bottles to the properties of concrete, and byIsmail and Al-Hashmi [10], in the adhesion resistance betweenthe surface of polymeric waste and the cement paste. Li et al.[13] have also verified a reduction in the compressive strength ofthe concrete with tire fibers, not relating such loss to any charac-teristic of the material.

0 5 10 15 20 25 300

10

20

30

40

Com

pres

sive

stre

ngth

(MPa

)

Curing ages (days)

RC LDPE 0.5% LDPE 1.0% LDPE 2.5% LDPE 5.0% LDPE 7.5%

Fig. 2. Compressive strength in terms of curing time for concrete made withrecycled LDPE.

0 5 10 15 20 25 300

10

20

30

40

Com

pres

sive

stre

ngth

(MPa

)

Curing ages (days)

RC PET 0.5% PET 1.0% PET 2.5% PET 5.0% PET 7.5%

Fig. 3. Compressive strength in terms of curing time for concrete made withrecycled PET.

0 5 10 15 20 25 300

10

20

30

40

Com

pres

sive

stre

ngth

(MPa

)

Curing ages (days)

RC TIRE 0.5% TIRE 1.0% TIRE 2.5% TIRE 5.0% TIRE 7.5%

Fig. 4. Compressive strength in terms of curing time for concrete made withrecycled tire.

0

5

10

15

20

25

30

35

40

Com

pres

sive

stre

ngth

(MPa

)

0

Content (%)

LDPE PET TIRE RC

7,55,02,51,00,5

Fig. 5. Comparative graph of compressive strength, at 28 days, of concretes withadditions of waste and its respective contents.

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Additionally, the tests indicated: compressive strength approx-imately equal or superior to the presented, at 7, 14 and 28 days ofcuring, by RC (34.3 ± 0.5) MPa, in compositions LDPE0.5, LDPE1 andLDPE2.5; PET0.5, PET1, PET2.5 and PET5; and TIRE0.5 and TIRE2.5.Evaluating the traces with TIRE, the need of improvement of dos-age process and conformation was noticed, as long as the interme-diate composition TIRE1 presented, at 28 days, lower compressivestrength, being also below the corresponding value of RC.

Bayasi and Zeng [4] showed similar effect on compressivestrength with the addition of polypropylene fibers, where thecontrol mixture (without polymeric fibers) showed a lowercompressive strength compared with mixtures with the additionof polypropylene fibers in given content. The 12.7 mm-long poly-propylene fibers improved the compressive strength of concretewhen used at volume fraction of 0.3%; in this case the increasewas 19.3% when compared with the control mixture. When usedat content of 0.5%, a decrease of 2.5% of compressive strengthwas noticed in concrete, in comparison with control mixture.

Experimental results showed that addition of polymer materialsat lower contents caused no adverse effects on the compressivestrength of concrete (Fig. 5). The LDPE0.5 and TIRE0.5 presented

an increase in compressive strength compared to the RC. This in-crease in compressive strength was observed in PET with contentof 2.5% of addition of recycled material. For the highest contentsof addition of polymeric waste a decrease in the compressivestrength of concrete occurred.

For the three materials, the ideal content in the mixture wasestablished as of 2.5%, in weight, the PET2.5 having the best perfor-mance, with (36.0 ± 0.6) MPa, followed by the other two materials,LDPE2.5 and TIRE2.5, with very similar values between both, of(33.9 ± 0.4) MPa and (33.7 ± 0.4) MPa, respectively, at 28 days, asillustrated in Fig. 5.

Although the reduction noticed in the compressive strength ofthese mixtures of concrete, the values are of moderate to highresistance [15]. Such compositions can be used in poles andcross-arms of reinforced concrete for electrical energy distributionlines, therefore, can also be used in the proper area of energy. Asthe inferior boundary value of this property recommended for suchstructures is of 25 MPa (NBR 8451/98), only the trace TIRE7.5 mustbe excluded.

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The environmental advantage of the use of rubber in concretemixtures can be evidenced in the experiment made with TIRE2.5mixture in test poles to be used at electrical energy distributionnet in the Northeast region of Brazil [20]. Four structures were con-formed, immobilizing about 20 kg of material, or 5 kg/pole. Consid-ering that about 4 kg of fragmented rubber can be removed from auseless tire, or about 0.8 kg from its tread and sidewall, in this caseabout one entire tire can be disposed for each pole. In the casewhere only the rubber from the tread is used, the number ups tosix tires. In the same Northeast region of Brazil, the local companyof electrical energy has an asset of 6 million units of installed poles,being foreseen annual substitutions of, approximately, 60,000units, or, an equivalent immobilization of 300 tons of rubber peryear or about 75,000 units of this type of tire. Following the recom-mendations of concrete pole standards (NBR 8451/98), the forecastof such immobilization is of 35 years maximum.

Table 8Mass loss of concrete samples under erosion–abrasion(underwater method).

Material Mass loss (%)

CR 6.57TIRE2.5 8.41TIRE5 7.39PET2.5 8.07PET5 5.04LDPE2.5 7.46LDPE5 3.94

1 2

4(a)

3.2. Tensile strength under diametrical compression

When the RM’s were compared in terms of tensile strength un-der diametrical compression, results indicated an unexpectedbehavior, without any direct relationship between strength, con-tent or type of the waste added to the concrete. Based on Siddiqueet al. [23] this behavior happens due to the absence of a fragile fail-ure, typical of conventional concrete.

In the graph of Fig. 6, results of splitting tensile strength of con-cretes are presented.

No direct relationship was verified between tensile strength un-der diametrical compression and recycled material content. Onaverage, the best results were for contents of 1% and 2.5%, inweight, for the three materials, with prominence of LDPE2.5, whichpresented tensile strength under diametrical compression of3.95 MPa, at 28 days.

One of the important factors to be investigated regarding theanalysis of fiber-reinforced concrete is the relationship betweencompressive strength and tensile strength. For conventional con-crete, tensile strength under diametrical compression is about10% of the compressive strength.

For LDPE, PET and TIRE materials, in the analyzed contents, therelationship between compressive strength and tensile strengthunder diametrical compression was of (10.4 ± 0.8)%. In this situa-tion, the fibers of the added materials worked as reinforcement,preventing the propagation of cracks [18,10,23].

0

1

2

3

4

5

Tens

ile s

treng

th (M

Pa)

Content (%)

LDPE PET TIRE RC

0 0,5 1,0 2,5 5,0 7,5

Fig. 6. Comparative graph of splitting tensile strength of concretes with addition ofwaste and its respective contents.

3.3. Erosion–abrasion resistance

In Table 8, the values of mass loss, after 72 h of erosion–abra-sion (underwater method), of CR and of concretes made with poly-meric waste in contents of 2.5% and 5.0% are presented.

Regarding mass loss by underwater erosion–abrasion, it wasobserved that CR presented the best results, in comparison withthe concrete made with addition of 2.5% of polymeric waste. How-ever, for the content of 5%, the concrete made with addition of PETand LDPE presented better results than the concrete without anyaddition. Horszczaruk [8] verified that the concrete strengthenedwith polymeric fiber has higher abrasive resistance when com-pared with concrete without fiber addition.

The resistance to erosion–abrasion, after 72 h, decreased in thefollowing order: LDPE, PET and TIRE. Such results can be attributedto shape, texture and elastic module of the employed materials:the LDPE, with average grain diameter smaller than 0.4 mm, hadthe best performance, with mass loss of around 7.46% for LDPE2.5composition. The poorest performance was presented by the mate-rials with the compositions TIRE2.5 and TIRE5. This can be based

3

(b)

Fig. 7. Micrograph by SEM of TIRE5 concrete (a) and respective EDS specter of theanalyzed region (b).

1054 J.C.A. Galvão et al. / Construction and Building Materials 25 (2011) 1049–1055

on its higher water absorption ratio, which is explained by thehigher amount of communicating pores and, consequently, smalleraverage compressive strength, with the rupture process happening,in most of the cases, in the interface ‘‘cement paste|fiber”, corrob-orating with the works of Raghavan and Huynh [21].

3.4. Microstructure after aging by SO2

In Fig. 7, the micrograph obtained by SEM of the broken surfaceof one of the TIRE5 specimens is presented, after the aging processof the specimen during 180 days in a humid chamber containingsulfur dioxide. Its respective specter of semi quantitative elemen-tary chemical composition is also shown.

In the inspected region it is shown the interface between therubber and the paste, the proper rubber (1) and, all over the exten-sion of the region and in diverse parts of the sample, crystals ofportlandite (2), gypsum (3), and ettringite (4), indicating a progres-sive degradation process of the structure [9]. This composition, inrelationship to PET and LDPE, presented a greater tendency to for-mation of these crystals, which are capable of compromising thedurability of concrete at industrial environments, given the ten-dency to higher concentrations of SOx gases in those areas. Thespecter of the region, obtained by EDS, is also shown in Fig. 7, beingpossible to point out the presence of the chemical element sulfur,that can be part of the proper elastomer and phases of sulpho-alu-minates, ettringite and gypsum which are present.

In Fig. 8, the micrographs by SEM of the broken surfaces of thecompositions LDPE5 (a) and PET5 (b) are presented, respectively. Itis evident the presence of polymeric waste from the partially in-serted materials in the paste, specific from LDPE (a), and also the

Fig. 8. Images by SEM of concrete with addition of polymeric waste: (a) LDPE5; (b)PET5.

resultant image or replica of the place that contained one of theblades of PET (b). In this last case, the lack of adherence betweenthe paste and the material was probably caused by the increasedsmoothness of the polymer texture. In the same image, otherplaces of removing of the related blades can be seen. Althoughthe tests of aging by SO2 were equally made with all the specimen,the results indicated that these two compositions had superior per-formance, not having in their broken surfaces and pores crystals ofchemical phases containing sulfur, resultant from the chamber oftests or from the proper composition of cement.

3.5. Application in field

The concretes with addition of polymeric waste and the CR didnot present any technical problems at the moment of its applica-tion as RM on the spillway surface of Mourão powerplant dam.As quoted by Siddique et al., the addition of polymeric waste re-duced the workability of the concrete. This reduction has been cor-rected with the use of plasticizing additive, keeping slump fixed at(30 ± 10) mm for all materials applied in field.

The tack bridge, with the use of structural adhesive based on anepoxy resin of high viscosity, proved to be, in the first hours, a reli-able element in the increase of tack resistance between the oldconcrete (substratum) and the new fresh concretes (RM).

In Fig. 9a, one of the six compositions applied in the spillway ofMourão powerplant is shown the repair material based on TIRE2.5,with 270 days of age and, in Fig. 9b, the details of its interface withthe substratum. Until the present moment, defects proceedingfrom the application, edge or deleterious actions (erosion–abra-sion) caused by the environment or the water flow in the flowingperiods of the barrage’s reservoir have not occurred.

Fig. 9. Photos of the RM based on TIRE2.5. (a) Detail of the region containing the RMTIRE2.5; (b) detail of its interface with the substratum.

J.C.A. Galvão et al. / Construction and Building Materials 25 (2011) 1049–1055 1055

4. Conclusions

(1) The addition of polymeric waste and elastomer materials(LDPE, PET and TIRE) in the ratios of 0.5%, 1.0%, 2.5%, 5.0%and 7.5% (in weight) reduced the workability of the manu-factured fresh concrete. It was analyzed that the workabilityis inversely proportional to the content of added polymericwaste. However, the use of plasticizing additive contributedto adjusting it, providing the fresh concrete with the desiredconsistency and workability.

(2) The compressive strength of the mixtures was also reducedwith the increase of the addition. In the maximum content of7.5% of addition, the reduction was of 38.48% for TIRE,26.24% for LDPE and 15.45% for PET.

(3) The polymeric waste added to the concrete has given to thematerial an increase of resistance to underwater erosion–abrasion testing.

(4) The concrete with addition of recycled tire presented agreater tendency to the formation of deleterious crystals ofaluminate, ettringite and gypsum phases, if compared tothe concretes manufactured with addition of recycled LDPEand PET.

(5) The concrete samples studied did not present technicalproblems during their application as repair materials in thehydraulic surface of the dam. For those materials, until thepresent moment, edge effect has not been identified.

(6) The addition of polymeric waste is viable, mainly whenthere are expected improvements in the properties ofdynamic order as resistance to the erosion–abrasion and ofoptimization or reduction of solid rejects in landfills. It wasverified that tons of rejects can be used in the energy distri-bution industry, in manufacturing of civil structures (polesand cross-arms) cast with similar composition.

The use of recycled materials added to concrete is a technologythat can constantly be improved, regarding technical and environ-mental conditions. Therefore, studies in this area are promising toits dissemination in the market.

Acknowledgements

To UTFPR and CAPES for the concession of PIQDTEC; to CNPq –PIBITI, for the allowance of technological initiation (Process303729/2008-2), to UFPR – PIPE; to COPEL, to LACTEC and ANEEL,for the financing and the infrastructure for the conduction of thisresearch project; to MENNOPAR for the supply of polymeric waste.

References

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