application of micronized pet as aggregate in...
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APPLICATION OF MICRONIZED PET AS AGGREGATE IN CONCRETE TO
PAVING
Salomão Pereira de Almeida1,a, Ana Maria Gonçalves Duarte Mendonça2,b*, John Kennedy Guedes
Rodrigues3,c, Yane Coutinho Lira 4,d,
1 Process Engineering Ph.D student, Universidade Federal de Campina Grande- UFCG, Paraíba, Brazil;
2 Researcher Professor, Universidade Federal de Campina Grande- UFCG, Paraíba, Brazil;
3 Associate Professor, Universidade Federal de Campina Grande- UFCG, Paraíba, Brazil;
4 Civil Engineering student, Universidade Federal de Campina Grande- UFCG, Paraíba, Brazil;
KEYWORDS: Concrete, Micronized PET, Aggregate, Pavement.
ABSTRACT
Polyethylene Terephthalate (PET) is a type of plastic largely used to produce packaging and many
other products. Due to the growing use of this material and its inadequate discharge in the environment,
it has become imperious the study and knowledge of its properties to find new uses in a way to reach its
maximum usage. Many materials used in paving have high costs and are progressively becoming
scarce. In this way, the construction sector has great potential to incorporate various types of residues,
for instance PET, in the execution of base and subbase layers or in coating. The present work aims to
analyze the possibility of applying micronized PET as aggregate in concrete to paving. It was observed
that to PET contents higher than 5.0% there is a decrease in properties as strength and durability of
concrete. Therefore, it is necessary the use of additives to promote the improvement of such properties.
Thus, the use of micronized PET in concrete to pavement is a viable alternative, being necessary the
establishment of contents that allow the obtainment of properties similar to those achieved by
conventional concrete.
1. INTRODUCTION
The construction industry is a very important activity around the world. It is linked to the
infrastructure of a country and contributes to great employment generation and income due to the
extensive volume of applied resources, being considered a development index. It represents the
generation of long-term investments in companies in industry, services and agricultural areas [1].
Concrete is the second most consumed material in the world, being only superseded by water.
According to [2], it happens not only due to its water resistance and low cost, but also because it
enables the composition of different structural elements with different forms and sizes, being useful in
the construction of bridges, dams, pre-molded elements, etc.
Over the years, interlocking paving (paver) has been highlighted in the national market, mainly
in paving fields, be it in squares, sidewalks, leisure areas, gas stations or parking lots. Interlocking
concrete paving is composed by precast elements, with no need of grout, been assented directly over a
“sand bed”. This rise is due to the several benefits proportioned, such as: higher permeability, ease in
laying, possibility of removal and re-layering and also the various colors, providing an esthetic
differential.
Besides, paver meets the needs of most part of pedestrians, once it enables level repair between
areas, it is slip resistant and presents special lines, easing locomotion of visually impaired.
In order to justify such growing, it is possible to analyse paver characteristics. Firstly, the
product provides higher permeability, excelling at rain water drainage, minimizing impacts caused by it
or due to unplanned urbanization, cooperating to the reduction of superficial flow. Secondly, the ease
of removal and later re-layering, in maintenance and infrastructure works, once it is not necessary the
use of grout to the union of blocks, and consequently breaks and the generation of residues.
PET is a thermoplastic polymer used in the production of packaging, mainly bottles to
carbonated beverages. Derived from petroleum, a non renewable substance, polyethylene terephthalate
packages take at least one hundred years to decompose, depending on the environment conditions.
Thus, in the course of their lifetimes, containers provoke environment degradation, polluting rivers and
oceans and unbalancing linked chains [3].
Among its characteristics, it is evidenced low density, excellent thermal stability, ease of
processing, low production cost, ease of molding, a high chemical and mechanic strength and an
excellent barrier to gases and odors [4].
2. MATERIALS AND METHODS
2.1 Materials
The materials used in the research are:
Polyethylene Terephthalate (PET): micronized PET supplied by PET Reciclagem company;
Cement: HES Portland cement – Type V;
Fine aggregate: Quartz sand from Paraíba River bed;
Coarse Aggregate: Granitic crushed stone with maximum diameter of 6.3 mm;
Water: Destined to human consumption and provided by Companhia de Águas e Esgoto da
Paraíba (CAGEPA).
2.2 Methodology
Figure 1 presents a flowchart with the steps in the development of the research.
Figure 1 – Flowchart of research.
2.2.1 Materials Characterization
Aggregates Characterization
Grain size Analysis
The grain size test determines the percentage distribution of different grain sizes of the
aggregate. It is represented by the grain size curve that shows the passing percentage for each sieve
versus the logarithm of the sieve opening diameter.
The grain size composition test for fine and coarse aggregate was performed according to test
method ABNT NBR 7217:1987.
Specific Gravity Determination
The specific gravity of an aggregate is the ratio between mass and volume, without considering
voids. This value is important in the quantification of materials to be used in concrete mix design.
The specific gravity of sand was determined using Chapman Flask, according to test method
ABNT NBR 9776:1987. Test method ABNT NBR NM 53:2003 was used to determine specific gravity
in coarse aggregate.
Unit Weight Determination
Unit weight of aggregate corresponds to the ratio between the mass of aggregate put in a
container and its volume. This test aims to determine the unit weight of fine aggregate, including voids
1st Step
2nd Step
3rd Step
Materials
Characterization
Dosage study
PET
Production of Concrete and Molding of Specimens
Determination of
mechanical properties
Compressive Strength
Sand
Granitic
crushed
stone
4th Step
and moisture present among grains and it is important in the determination of mix design. Using this
value, it is possible to convert mix designs from mass to volume during dosage procedure
The test was performed with fine aggregate according to ABNT NBR 7251:1982.
Pulverulent materials content Determination
Pulverulent materials are mineral particles that pass through sieve n° 200 with opening of
75µm, including water soluble materials present in the aggregate.
This test, whose goal is to determine pulverulent materials content in the aggregates destined to
production of concrete, was performed with fine aggregate according to ABNT NBR 7219:1987.
Absorption
It is the increase in mass of a porous solid due to the penetration of a liquid in its permeable
pores, compared to the mass in dry state.
The absorption of coarse aggregate was determined according to test method ABNT NBR NM
53:2003. Depending on the value obtained, an adjustment in water/cement ratio to mix design can be
done.
Cement Characterization
Specific Gravity
In the determination of specific gravity for cement, Le Chatelier Flask was used, according to
test method DNER – ME 085/1994.
Fineness Test
It is the determination of the percentage, in mass, of Portland cement whose grain dimensions
are superior to 75 μm, using manual sieving method according to test method ABNT NBR 11579:2012.
It is important to know the fineness value of cements, because when this value is high it means there
was cement hydration and consequently loss of its characteristics. The finer is the cement, the better is
its hydration reaction and mechanic strength of mortar.
PET Characterization
Chemical Analysis – EDX
This test provides important information to industrial and scientific use and consists in
submitting the sample to an X- ray fluorescence, in which physical-chemical components of the
material are identified. The material (PET) was processed in sieve ABNT Nº 200 (opening: 0.074mm)
and the test was performed in an EDX 720 Shimadzu equipment.
X – Ray Diffraction
This technique enables the determination of the structure of crystalline solids, the atomic
arrangement in crystalline reticles or in a sole crystal of a particular substance, based on the
interference patterns of x radiation diffracted by the reticles, allowing the determination of the main
elements that compose the material. The test was performed in a Shimadzu XDR-6000 equipment,
using Cukα radiation, voltage of 40kV, current of 30mA, scanning of 2º< 2ɵ< 30º and λ1.54ª.
Thermal Differential (DTA) and Thermal Gravimetric Analysis (TGA)
Thermal Differential (DTA) and Thermal Gravimetric (TGA) Analysis of PET were performed
using BP Engenharia equipment, RB 3000 Model, operating at 12.5ºC/min. The maximum temperature
in thermal analysis was 300ºC and the reference material used in DTA test was calcined alumina
(Al2O3).
3. RESULTS AND DISCUSSION
Physical Characterization of fine aggregate (quartz sand)
The fine aggregate used in the research was quartz sand from Paraíba River bed. Table 1
presents the results obtained in the grain size test.
Table 1 – Grain size composition of fine aggregate (quartz sand).
Grain size composition (ABNT NBR 7217:1987)
Sieves
(mm)
Retained Material (g) Percentage in mass (%)
Retained Accumulated
2.4 28.95 2.90 2.90
1.2 79.09 7.91 10.81
0.6 326.32 32.65 43.46
0.3 420.85 42.11 85.56
0.15 140.28 14.04 99.60
Bottom 4.00 0.40 100.00
Total 999.49 100.00 -
Fineness Modulus (FM) 2.42
Maximum Diameter(MD) 2.36 mm
The results obtained for maximum diameter and fineness modulus were 2.42 mm and 2.36,
respectively. The sands are divided, with regard to grain size, into very coarse, coarse, medium, fine
and very fine sands, depending on the fineness modulus, determined by the sum of percentages retained
accumulated in the normal series of sieves, divided by 100.
According to the fineness modulus, the sand was classified as fine/medium sand, belonging to
the optimum zone and not presenting deficiency or excess of any particle size, producing a more
economic and workable mortar of concrete. In this way, it was possible to trace the grain size curve
(Figure 2).
Figure 2 – Grain size curve of fine aggregate (quartz sand).
In the characterization of fine aggregate, specific gravity, unit weight and pulverulent materials
content tests were performed. Table 2 presents results for fine aggregate characterization.
Table 2 –Characterization of fine aggregate (quartz sand).
Test Test Method Result
Specific Gravity
(ABNT NBR 9776:1987) 2.618g/cm³
Unit Weight
(ABNT NBR 7251:1982) 1.429g/cm³
Pulverulent Materials Content
(ABNT NBR 7219:1987) 0.07%
The specific gravity of fine aggregate of 2.618 g/cm³ was obtained using Chapman Flask
(ABNT NBR 9776:1987), as seen in Figure 3.
Figure 3- Determination of specific gravity of fine aggregate using Chapman Flask.
The value obtained for unit weight of fine aggregate was equal to 1.429 g/cm³. This value was
determined from the filling of a cylindrical container by fine aggregate, as illustrated in Figure 4,
adopting precautions to avoid particle segregation in the sample.
Figure 4 – Execution of unit weight determination test.
In the pulverulent materials content test, the test method determines that the washing water of
aggregate must be clean. In this way, it was observed that after four washings during two minutes each,
the washing water stored on beckers did not present an expressive color change, indicating that
pulverulent material content in the sample was not significant. Therefore, the procedure was interrupted
in order to avoid abrasion among particles.
Figure 5 – Washing water from fine aggregate sample.
The value found for pulverulent materials content for sand was equal to 0.07%. It means that
99.93% of the fine aggregate sample was formed by sand grains.
Physical Characterization of coarse aggregate (granitic crushed stone)
Granitic crushed stone was used as coarse aggregate, with maximum dimension of 6.3 mm. The
results for physical characterization of coarse aggregate are exposed in Table 3.
Table 3 – Physical characterization of coarse aggregate (granitic crushed stone).
Tests Test Method Results
Density ABNT NBR NM 53:2003 s = 2.63 g/cm3
Saturated surface dry specific gravity ABNT NBR NM 53:2003 sss = 2.64 g/cm3
Apparent Specific Gravity ABNT NBR NM 53:2003 a = 2.67 g/cm3
Absorption
ABNT NBR NM 53:2003 Abs = 0.66%
According to the results presented in Table 3, it is verified that the specific gravity and
absorption of the coarse aggregate used in the research were equivalent to 2.63 g/cm3 and 0.66%,
respectively.
Table 4 shows the grain size distribution of coarse aggregate.
Table 4 – Grain size composition of coarse aggregate (granitic crushed stone).
Grain Size Composition (ABNT NBR 7217:1987)
Sieves
(mm)
Retained material (g) Percentage in mass (%)
Retained Accumulated
6.3 2382.00 39.70 39.70
4.8 2604.00 43.40 83.10
2.4 955.20 15.92 99.02
1.2 22.20 0.37 99.39
0.6 6.40 0.11 99.50
0.3 5.11 0.09 99.58
0.15 6.04 0.10 99.68
Bottom 18.54 0.31 99.99
Total 5999.49 100.0
Fineness Modulus (FM) 6.19
Maximum Diameter(MD) 6.3mm
As seen in Table 4, the coarse aggregate has a fineness modulus of 6.19 and maximum diameter
of 6.3 mm, having the most part of material retained in sieves with openings of 6.3 mm and 4.8 mm.
Physical Characterization of cement.
The cement used in the research was a High Early Strength cement type V, once it has high
performance. It was developed to application in the precast industry and concrete pieces, where it is
necessary a fast demolding and high strength at initial ages.
The specific gravity and fineness modulus of cement are presented in Table 5.
Table 5 – Physical characterization of cement.
Test Test Method Result
Specific Gravity
DNER – ME 085/1994 3.10g/cm³
Fineness
ABNT NBR 11579:1991 1.40%
It is observed that the fineness modulus found was 1.40%. This value meets the maximum value
of 12% stablished by test method ABNT NBR11579:1991.
Chemical Characterization of Polyethylene Terephthalate - PET
The chemical analysis of micronized PET was performed using X – Ray Fluorescence test.
Table 6 shows the chemical composition of Polyethylene Terephthalate.
Table 6 – Chemical composition of Polyethylene Terephthalate.
Determination (%)
Micronized PET
LF SiO2 Al2O3 Fe2O3 CaO TiO2 K2O
0.24 38.70 31.21 14.31 6.76 5.77 3.25
LF: Loss on Fire
According to the results presented in Table 6, it is observed that Polyethylene Terephthalate
(PET) is basically constituted by silica (38.70%), Al2O3 (31.21%), Fe2O3 (14.31%), CaO (6.76%), TiO2
(5.77%) and K2O (3.25%).
Production of Interlocking Blocks
After materials characterization, the mix design and water/cement ratio were defined.
Specimens in the format of interlocking blocks, with 16 faces and dimensions of 24cmx10cmx4cm
(Figure 6), were molded. The process used in the production of blocks consists in keeping the concrete
in the molds overnight and, as the molds are plastic, the block remains with a surface finishing
extremely plain.
Figure 6 – Demolding of specimens.
It was used a plastic concrete with the following mix design: 1:3, (cement-aggregate). The
additive corresponded to 0.8% of cement mass. In all cases, half of the aggregate was granitic crushed
stone and the other half was composed by sand and PET in different quantities. The water/cement ratio
was chosen: 0,45. For each factor, blocks were produced with 0.0% of PET (reference mix design).
Next, occurred the molding of blocks, with partial replacement of fine aggregate (sand) by micronized
PET in the percentages of 2.5%, 5.0%, 7.5% and 10.0% of the total mass of aggregate, on a total of 45
combinations.
Mechanic Characterization
The mechanic characterization was performed through characteristic strength (fck) test
according to test method ABNT NBR 9781/2013. Figure 7 illustrates the determination of compressive
strength.
Figure 7 – Compressive Strength test. LEP/UFCG.
Table 7 presents the proportions of materials used in the production of specimens.
Table 7- Proportions of materials used in the production of specimens.
PROPORTIONS OF MATERIALS
%
PET W/C RATIO CEMENT
GRANITIC
CRUSHED
SONE
SAND PET WATER
0.0 0.45 600 g 900 g 900 g 000 g 270 g
2.5 0.45 600 g 900 g 855 g 45 g 270 g
5.0 0.45 600 g 900 g 810 g 90 g 270 g
Figure 8 presents the evolution of compressive strength in the produced concrete specimens
with replacement of fine aggregate by micronized PET (2.5% and 5.0%).
Figure 8 – Evolution of characteristic strength (fck) of concrete.
The strength is closed linked to concrete porosity. However, as the pores were partially or
totally filled by the polymer, the support area for effective loading, to which the concrete was
submitted, was expanded, favoring the increase in mechanic strength. Interlocking blocks that reach
strengths above 50 MPa are considered high strength floors and are indicated to areas where there is an
intense circulation, for instance: petrochemical industries; metallurgical industries, especially in
productive areas like machining sectors, thermal treatment, stamping, forging and casting, meatpacking
industries, where hygiene is fundamental, food industries, among others.
4. CONCLUSIONS
According to the obtained results, it is possible to conclude that:
The replacement of fine aggregate by micronized PET enabled the obtainment of a concrete
with higher strengths, compared to the reference concrete. This is justified by a better packaging of
particles, reducing porosity and consequently improving mechanical strength.
5. REFERENCES
ABNT - Associação Brasileira de Normas Técnicas - Cimento Portland de alta resistência inicial. NBR
5733 EB 2, 5 p. Rio de Janeiro, 1991.
___________ - Cimento Portland – Determinação da resistência à compressão. NBR 7215, 8 p. Rio de
Janeiro, 1996.
___________ - Concreto e argamassa – Determinação da resistência à tração por compressão
diametral. NBR 7222, 5p. Rio de Janeiro, 2010.
___________ - Argamassas e concreto endurecidos - Determinação da absorção de água por imersão,
índice de vazios e massa específica. NBR 9778, 4 p. Rio de Janeiro, 2005.
___________ - Cimento Portland – Variação dimensional de barras de argamassas expostas à solução
de sulfato de sódio. NBR 13583, 12 p. Rio de Janeiro, 1996.
___________ - Agregados - Determinação da absorção e da massa específica do agregado graúdo –
Método de ensaio. NBR NM 53, 8p. Rio de Janeiro, 2003.
______. NBR 7217: Determinação de composição granulométrica dos agregados. Rio de Janeiro, 1982.
______. NBR 7219: Determinação do teor de materiais pulverulentos nos agregados. Rio de Janeiro,
1982.
______. NBR 7251: Agregados no estado solto – Determinação da massa unitária. Rio de Janeiro,
1982.
______. NBR 9776: Determinação da massa especifica de agregados miúdos por meio do frasco de
Chapman. Rio de Janeiro, 1987.
______. NBR 11579: Cimento Portland Comum – Determinação do modulo de finura. Rio de Janeiro,
2012.
[1] M. B. Chagas Filho, Estudo de Agregados Lateríticos para Utilização em Concretos Estruturais.
Tese - Universidade Federal de Campina Grande, Campina Grande, 2005.
[2] P. K, Mehta, P. J. M. Monteiro. Concreto: microestrutura, propriedades e materiais. 3ed. São Paulo:
IBRACON, 2008.
[3] T. Silvestre. Brasil descarta 53% de garrafas PET na natureza.
http://www.revistameioambiente.com.br/2007/11/15/brasil-descarta-53-de-garrafas-pet-nanatureza.
Acessed in: 11 may, 2013.
[4] J. L. S. Aquino. Desenvolvimento de compósitos de matriz cimentícia utilizando resíduos de
politereftalato de etileno (PET) e de areia de britagem na produção de concretos. Tese (Doutorado) –
Universidade Federal de Campina Grande, Campina Grande, 2013.