ANALYSIS OF REPLACEMENT OF PORTLAND CEMENT BY MICRONIZED POLYETHYLENE TEREPHTHALATE IN THE PRODUCTION OF CONCRETE

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1 ANALYSIS OF REPLACEMENT OF PORTLAND CEMENT BY MICRONIZED POLYETHYLENE TEREPHTHALATE IN THE PRODUCTION OF CONCRETE Mauro Henrique Alves Nascimento¹,a ; Ana Maria Gonçalves Duarte Mendonça²,b ; John Kennedy Guedes Rodrigues³,c, Taíssa Guedes Rodrigues 4,d 1 Civil Engineering Master 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 a maurohanascimento@gmail.com, b ana.duartemendonça@gmail.com, c profkennedy@hotmail.com d taissaguedes1@hotmail.com KEYWORDS: Concrete, Portland cement, Polyethylene Terephthalate (PET), Recycling, Chemical, Mineralogical and Thermal Properties. ABSTRACT Tied to the industrial and population growing is the search for new technologies and materials that meet the sustainable development concept. In the disposable packaging production industry, it is highly used Polyethylene Terephthalate PET, a low density, transparent, easy to mold product that also provides high mechanic and chemical resistance. However, this product, derived from petroleum, a non-renewable substance, can take centuries to naturally decompose and when incorrectly disposed generates a huge environmental impact, being necessary its reuse. In turn, the great demand for concrete around the world propelled the construction sector to search for new materials that introduce the necessity of reduction, reuse and recycling. Faced with this scenery, the present work presents a comparative study between chemical, mineralogical and thermal properties of micronized polyethylene terephthalate and Portland cement, aiming to reduce the proportion of cement by cubic meter of concrete produced. This can provide a reduction of costs and offer a noble destination for PET after consumption through a possible replacement, in mass, of cement by micronized PET in the concrete production process. For the determination and subsequent comparison between the properties of PET and Portland cement, it was adopted in the methodology differential thermal analysis (DTA) and thermal gravimetric analysis (TGA) as well as determination of chemical properties using X-Ray Fluorescence (XRF). Through the results obtained, it is possible to conclude that micronized PET presents similar properties to Portland cement, providing a possible recycling of PET in concrete production.

2 1. INTRODUCTION The solid urban residues issue is linked to evolution processes and men development. This residue generation due to the diverse human activities is a great challenge to be faced by the current generation. Another issue related to such residues resides in the fact that the production speed surpass the degradation capacity of the compounds in the environment, compromising natural resources and life quality of current and future generations. Two sectors of the Brazilian industry that fit into this issue are the PET industry and the construction industry, because they cause huge environment impacts, whether by natural resources consumption, landscape modification or residues generation. In contrast, according to [1] the growing awareness about the environment has contributed to concerns about the elimination and reuse of generated residues. The solid waste management is one of the main environmental concerns in the world. With the shortage of deposition space in landfills and due to the higher cost, the use of residues has become an alternative to avoid their deposition. The Polyethylene Terephthalate (PET) is used in products with short lifetime, such as packages. Due to the high amount and variety of applications of PET packages and its long-term degradation, they are considered one of the environment villains, once they occupy a good volume in landfills and mainly because they are discharged directly in nature, causing visual pollution in urban centers. However, environmental problems are not caused by the production of PET but by its inadequate discharge. In this way, systematic recycling is the solution to minimize this environmental impact. Even discharged in landfills, PET packages represent a problem to the public power, once that because of its long-term decomposition (more than 100 years) and the high volume occupied, when discharged in large amounts, they diminish the storage capacity of landfills and provoke a superficial sealing of soil, forming an impermeable layer that impedes circulation of gases and liquids, affecting the organic matter decomposition process [2]. According to the Brazilian Association of PET Industry (ABIPET) [3] the Brazilian production in 2012 was of 562 thousands of tons, 59% of which were recycled (331thousands of tons). This is superior to the average in USA and similar to European countries, where recycling activity is more professionalized. However, from the 562 thousand tons of PET consumed in 2012 in Brazil, approximately 40% were not reused, occasioning a discharge in nature of 231 Ktons of this material, causing serious environmental problems. The main consumer of recycled PET in Brazil is the textile industry with 38.2%, industries of unsaturated and alkyd resins with 23.9% and packaging industries with 18.3%. New alternatives to reuse these packages after consumption must be investigated, in a way to avoid discharge in landfills and in the environment. The awareness of technological characteristics of residues increases the possibility of products produced with such materials, besides the reduction in the generation of harmful residue, once that every processing activity generates residues [4]. Along with the need for PET recycling, there is the search, in the construction sector, for constructive techniques that take advantage on the diverse available resources, preserving the nonrenewable natural resources and avoiding the use of materials and technologies harmful to the environment. The construction sector is a great consumer of natural resources. Water, sand, granitic crushed stone and mainly cement are the more traditional resources employed in concrete

3 production. Besides, main suppliers of civil construction are among the biggest polluters in the world, especially the cement industry that daily discharge tons of industrial waste in the environment, mainly gases and dust formed in the productive process and in the burn of fuels in the rotatory ovens. According to National Union of Cement Industry [6] the production of cement in Brazil in the first eleven months of 2014 reached approximately 70 thousand tons of cement. One of the great villains in the productive chain of civil construction is the cement, the most used input of the sector. Cement, according to [7], is a binder (pulverulent material that hydrates in the presence of water, forming a strong paste able to bind aggregates) known worldwide as Portland cement. The production of Portland cement occurs through the milling of a product called clinker, obtained by the calcination (oxidation by heat) of a raw mixture of limestone and clay, dosed and homogenized. This process occurs by the intense burning of fuels, in rotating ovens, delivering a final product in the form of dark nodes that, after cooled, are milled and receive the addition of gypsum, whose action is to stop hydration reactions between cement and water that instantly occur [7]. The cement manufacturing process consumes huge amounts of energy, in the form of heat (in rotating ovens) or electric energy in the industrial process. Based on this, cement has an important function on the construction sector, having a generalized use in great volumes. Thus, the search for materials that can replace it, even partially, in the production of concrete is the first step to minimize its impact in the environment [5]. In this context, as the PET Recycling Industry is one of the most developed in the world and has high recycling index and a variety of application for the recycled material, it creates a constant and assured demand, favoring the possible replacement, in percentages, of Portland cement by Polyethylene Terephthalate, after consumption, in the production of concrete. As the search for alternatives to the reuse of PET, this research aims to evaluate the technical viability, using chemical-mineralogical analysis, of recycling Polyethylene Terephthalate in the production of concrete, replacing, in percentages, Portland cement. 2. MATERIALS AND METHODOLOGY 2.1. Materials In the development of the present research, the following materials were used: Cement: High Early Strength Portland Cement, type V [Figure 1]; Figure 1 HES Portland Cement.

4 Polyethylene terephthalate: micronized PET from PET Reciclagem industry, located at Campina Grande PB, Brazil [Figure 2]; Figure 2 Micronized PET Methodology The present study aims to perform a comparative analysis between chemical, mineralogical and thermal properties of micronized polyethylene terephthalate and HES V Portland Cement. In order to reach this goal, the methodology exposed in Figure 3 was adopted. Materials Characterization 1 st Step HES V Portland cement Characterization X-Ray Fluorescence (XRF); Differential Thermal Analysis (DTA); Thermal Gravimetric Analysis (TGA). 2 nd Step Polyethylene terephthalate Characterization X-Ray Fluorescence (XRF); Differential Thermal Analysis (DTA); Thermal Gravimetric Analysis (TGA). 3 rd Step Results Analysis and Research Conclusion Figure 3 Flowchart of research steps. The present research was divided into three steps. The first and second steps corresponded to Portland cement and Polyethylene terephthalate characterization, enabling the analysis of results and research conclusions, which was the third step. Chemical, Mineralogical and Thermal analysis were performed according to procedures used in Materials Characterization Laboratory at Science and Technology Centre of Federal University of Campina Grande PB, Brazil.

5 The methodology adopted to chemical, mineralogical and thermal analysis of materials is described below X-Ray Fluorescence (XRF) Analysis It is a chemical analysis technique used to determine qualitative and quantitative composition of components of a given material through x-ray emission. The principle of this method consists in the use of a radiation source to ionize inner levels of constituent atoms in the sample, by photoelectric effect. In the atom reorganization and regress to its fundamental state, it liberates the excess of energy through the emission of an X photon, whose energy is equal to the binding energy difference of the two orbitals involved. Such radiation has the characteristic energy of the element. The detection and analysis of the spectrum allows the identification and quantification of constituent elements in the sample. The chemical analysis by X Ray Fluorescence were determined by wet method and by Energy Dispersive X-Ray Analysis (EDX), using a SHIMADZU spectrometer, EDX-720 model. It was determined loss on fire, insoluble residue and present oxides (SiO 2, Al 2 O 3, CaO, MgO, Na 2 O, K 2 O and Fe 2 O 3 ) Differential Thermal and Thermal Gravimetric Analysis An equipment produced by BP Engenharia, RB 3020 model, was used to the thermal analysis and the samples were heated until 220ºC for PET and 1000ºC for Portland cement, with heating ratio of 12.5ºC/min. Thermal Gravimetric (TGA) and Differential Thermal (DTA) Analysis were performed using calcined alumina (Al 2 O 3 ) as reference material. 3. RESULTS AND DISCUSSIONS The determination of qualitative and quantitative composition of PET and cement oxides was made by x-ray fluorescence experimental procedure (EDX). Tables 1 and 2 present the chemical composition of Polyethylene terephthalate and Portland cement, respectively. Table 1 Chemical composition of PET. Determination of PET chemical components in percentage Loss on Fire SiO 2 Al 2 O 3 Fe 2 O 3 CaO TiO 2 K 2 O Micronized PET Table 2 Chemical composition of HES V Portland cement. HES V Portland Determination of cement chemical components in percentage LF SiO 2 Al 2 O 3 Fe 2 O 3 CaO TiO 2 K 2 O SO 3 MgO

6 cement LF: Loss on Fire It is observed in Table 1 that the micronized Polyethylene terephthalate (PET) is basically constituted by silica (38.70%), Al 2 O 3 (aluminum oxide), Fe 2 O 3 (iron oxide), CaO (calcium oxide), TiO 2 (titanium oxide) and K 2 O (potassium oxide). The higher proportion of components was composed by silica and aluminium oxide, representing 38.70% and 31.21%, respectively. From these proportions, PET can be classified as an aluminosilicate complex. According to [8], the main components of cement chemical composition, whose quantity directly influences the characteristics of the concrete produced, are: calcium oxide (CaO),silica (SiO 2 ), aluminum oxide (Al 2 O 3 ), iron oxide (Fe 2 O 3 ), magnesium oxide (MgO), alkalis (Na 2 O e K 2 O) and sulphates (SO 3 ). Among these components, calcium oxide, silica, aluminium oxide, iron oxide and potassium oxide are also present in PET composition, as seen in Table 1 [9] determines that the specific conditions of loss on fire and magnesium oxide (MgO) chemical requirements must have upper limit, in relation to cement mass percentage, of 4.5% and 6.5%, respectively. Such normative requirements are respected by PET, as seen in Table 1, once that magnesium oxide is not present in its composition, and the loss on fire is 0.24%, which means it is 99.66% inferior to the value required by test method [9] On one hand, the percentage of lime (CaO) in PET is 6.76%, which is inferior to the value found in cement composition, between 60% and 67%, according to [8]. This difference in the percentage of lime impedes the replacement of cement by PET, once that lime is an essential component of cements, responsible for strength characteristics. On the other hand, PET has silica (SiO 2 ), aluminium oxide (AlO 3 ) and iron oxide (FeO 3 ) percentages superior to the ones defined by [8] as being the maximum values found in cement, which are respectively 17%, 3,6% e 3,05%. In this way, PET has potential to replace Portland cement in the production of concrete; however, it is limited due to the low quantity of lime. Figure 4 presents Differential Thermal and Thermal Gravimetric analysis of micronized Polyethylene terephthalate.

7 Figure 4 PET Differential Thermal and Thermal Gravimetric results. Analyzing the results presented in Figure 4, it is observed the presence of an endothermic peak at 82 C approximately, related to the change in physical state (solid to liquid), having a significant loss in PET mass and the occurrence of an exothermic peak at 129 C indicating another change in physical state (liquid to vapor). From the thermal gravimetric curve, it is observed a total mass loss of 0.24% The differential thermal and thermal gravimetric analysis of HES V Portland cement are presented in Figure 5. Temperature / C Figure 5 DTA and TGA results for HES V Portland cement. Source: MEDINA, 2011.

8 According to the results obtained by [10] and presented in Figure 5, it is observed three main loss bands: the first between 30 C and 370 C, referring to gypsum, ettringite and syngenite decomposition [11]. The second band, between 370 C and 525 C, referring to portlandite Ca(OH) 2 decomposition and the third between 525 C and 1000 C, referring to calcium carbonate (CaCO 3 ) decomposition. Portlandite content was equal to 1.69% and calcium carbonate content at anhydrous cement was equal to 6.17%. It is observed that both cement and polyethylene terephthalate have loss bands beginning at a temperature of 30 C. However, for PET, mass losses are referent to chance of physical state, while for cement there is constituent s decomposition. Cement presented a higher mass loss, equal to 2.72%. 4. CONCLUSION From the results obtained, it is possible to conclude that Polyethylene terephthalate (PET) presents similar composition to Portland cement, but in different proportions. Therefore, due to the need for PET recycling allied to the search, in the construction sector, for sustainable techniques, PET has potential to replace Portland cement in concrete production. However, the replacing percentage must be limited to avoid damages to the concrete produced, once that, as seen in the chemical analysis, PET presents low quantity of lime in its composition. 5. ACKNOWLEDGEMENTS To Universidade Federal de Campina Grande UFCG PB. Brazil; To the Civil Engineering Department CTRN UFCG; To Ph.D. Professor Ana Maria Gonçalves Duarte Mendonça, for guidance in this research; To brazilian society for enabling me to study in Federal de Campina Grande UFCG PB. Brazil. 6. REFERENCES [1] R. Siddique, J. Khatib, I. Kaur. Use of recycled plastic in concrete: a review. Waste Management, v. 28, p , [2] A. Magrini. Impactos ambientais causados pelos plásticos: uma discussão abrangente sobre os mitos e os dados científicos. 2. ed. Rio de Janeiro: E-papers, [3] ABIPET. Página principal (home). Associação Brasileira da Indústria do PET, < Acesso em Junho de [4] S. S. Canellas. Reciclagem de PET, visando à substituição de agregado miúdo em argamassa. Rio de Janeiro, p. Dissertação de Mestrado - Departamento de Ciência dos Materiais e Metalurgia, Pontifícia Universidade Católica do Rio de Janeiro. [5] A. M. M. Santi, A. O. Sevá Filho. Combustíveis e riscos ambientais na fabricação de cimento. Artigo apresentado no II Encontro Nacional de Pós-graduação e Pesquisa em Ambiente e Sociedade ANPPAS: Campinas/SP, [6].SNIC. Sindicado Nacional da Indústria do Cimento, < Acesso em Junho de 2015.

9 [7] C. C. Ribeiro, J. C. da Silva Pinto, T. Starling. Materiais de construção civil. Belo Horizonte: Editora UFMG, [8] E. G. R. Petrucci. Concreto de Cimento Portand. 8. Ed. atualizada e ve / por Vladimir Antonio Paulo. Rio de Janeiro, [9] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR Cimento Portland de Alta Resistência Inicial. Rio de Janeiro, [10] E. A. Medina. Pozolanicidade do Metacaulim em Sistemas Binários com Cimento Portland e Hidróxido de Cálcio. Dissertação (Universidade de São Paulo), engenharia de Construçaõ Civil e Urbana, 134fls, 2011, São Paulo. [11] S. H. Kosmatka, B. Kerkhoff, W. C, Paranese. Design and control of concrete mixtures. 7 th edition, Cement association of Canada, Ottawa, Ontario, Canada, 368 pages, 2002.