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Ambiente Construído
Artigos • Ambient. constr. 18 (4) • Oct-Dec 2018 • https://doi.org/10.1590/s1678-86212018000400312 copy
Iron ore tailings in the production of cement tiles: a value analysis on building sustainability
Rejeito de barragem de minério de ferro na produção de ladrilhos hidráulicos: uma análise de valor para sustentabilidade de edificações
Wanna Carvalho Fontes
Universidade Federal de Ouro Preto Ouro Preto - MG - Brasil Wanna Carvalho Fontes Programa de Pós-Graduação em Engenharia Civil | Universidade Federal de Ouro Preto | Campus Morro do Cruzeiro | Ouro Preto - MG - Brasil | CEP 35400-000 | Tel.: (31) 3559-1547 | E-mail: wannarquit@gmail.com
Giovanni Gonçalves Fontes
Faculdade Dom Luciano Mendes Mariana - MG - Brasil Giovanni Gonçalves Fontes Programa de Pós-Graduação em História da Arte | Faculdade Dom Luciano Mendes | Rodovia dos Inconfidentes, Km 108, Mariana - MG - Brasil | CEP 35420-000 | Tel.: (31) 3558-1439 | E-mail: gigiogf@gmail.com
Ellen Cristine Pinto Costa
Universidade Federal de Ouro Preto Ouro Preto - MG - Brasil Ellen Cristine Pinto Costa Departamento de Arquitetura | Universidade Federal de Ouro Preto | Campus Morro do Cruzeiro | Ouro Preto - MG - Brasil | CEP 35400-000 | Tel.: (31) 3559-1484 | E-mail: ellencosta425@gmail.com
Julia Castro Mendes
Universidade Federal de Ouro Preto Ouro Preto - MG - Brasil Julia Castro Mendes Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | Tel.: (31) 3559-1546 | E-mail: jcmendes.eng@gmail.com
Guilherme Jorge Brigolini Silva
Universidade Federal de Ouro Preto Ouro Preto - MG - Brasil Guilherme Jorge Brigolini Silva Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | E-mail: guilhermebrigolini@gmail.com
Ricardo André Fiorotti Peixoto
Universidade Federal de Ouro Preto Ouro Preto - MG - Brasil Ricardo André Fiorotti Peixoto Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | E-mail: ricardo.fiorotti@ufop.edu.br
The present work discloses the development of a sustainable cement tile (SCT) produced with Iron Ore Tailings from tailings dams (IOT). Initially, technical evaluation and environmental analysis of IOT were performed through physical, chemical and morphological characterisation, leaching and dissolution tests. Its feasibility as a pigment was also investigated. Subsequently, the value analysis was performed, starting from an empathy map to a study on environmental, social and emotional values in the relationship between people and product. As result, the IOT presented fine, crystalline particles, no toxicity, and is technically feasible to be employed as filler, aggregate and pigment in the production of SCT. The colour layer of the SCT presented more homogeneous colour and less pores than conventional ones. Therefore, the design of the SCT was developed, incorporating intangible values such as: environmental ideology, local identity and social expression. In this sense, the present work seeks to assist in the decision-making process involving IOT as construction material.
Sustainable building materials; Cement tiles; Iron ore tailings; Value analysis
O presente trabalho abrange o desenvolvimento de ladrilho hidráulico sustentável (LHS) produzido com rejeitos de barragem de minério de ferro (RBMF). Inicialmente, a avaliação técnica e a análise ambiental do RBMF foram realizadas através de testes de caracterização física, química e morfológica, lixiviação e dissolução. Sua viabilidade como pigmento também foi investigada. Posteriormente, a análise de valor foi realizada, partindo de um mapa de empatia até o estudo sobre valores ambientais, sociais e emocionais na relação entre pessoas e produtos. Como resultado, o RBMF se apresentou como partículas finas, cristalinas, sem toxicidade, sendo tecnicamente viável para ser empregado como fíler, agregado e pigmento na produção de LHS. A camada de cor do LHS apresentou cores mais homogêneas e menos poros do que as convencionais. Assim, o projeto do LHS foi desenvolvido, incorporando valores intangíveis como: ideologia ambiental, identidade local e expressão social. Nesse sentido, o presente trabalho busca ajudar nas tomadas de decisão envolvendo RBMF como material de construção.
Materiais de construção sustentáveis; Ladrilhos hidráulicos; Rejeitos de barragem de minério de ferro; Análise de valor
Brazil is currently one of the world leaders in exploitation of mineral resources. Billions of tons of metal ores are mined in the country every year, and millions of tons of tailings and wastes are disposed of, mainly in tailing dams (FIGUEIRÔA, 2014FIGUEIRÔA, S. Mining in Brazil. In: SELIN, H. (Ed.). Encyclopedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Amsterdam: Springer, 2014.; INSTITUTO…, 2015INSTITUTO BRASILEIRO DE MUSEUS. Information Regarding the Brazilian Mining Economics. Brasília, 2015.). Since the beginning of the 18th century, the mining industry has been concentrated in the state of Minas Gerais, responsible for the largest production of iron ore, gold, zinc and niobium of the country (IBRAM, 2014INSTITUTO BRASILEIRO DE MUSEUS. Information on the Mineral Economy of the State of Minas Gerais. Brasília, 2014.). In Minas Gerais are accounted 445 of the 663 tailings dams in Brazil (FUNDAÇÃO…, 2014FUNDAÇÃO ESTADUAL DO MEIO AMBIENTE. Inventário de Barragens de Minas Gerais: ano 2014. Belo Horizonte, 2014.). As a result of the high volumes of production and poor management of residues, a dam recently collapsed in Minas Gerais, leading to the release of 62 million cubic meters of iron ore tailings (IOT), several casualties, and an expressive impact on the ecosystems over a 100km radius (G1, 2015G1. Tailings From Dams Reach Areas Up to 100km in MG. 2015. Available: <http://g1.globo.com/minas-gerais/noticia/2015/11/hidreletrica-100-km-e-afetada-por-lama-do-rompimento-de-barragens.html>. Access: 20 November 2015.
http://g1.globo.com/minas-gerais/noticia... ). Mining operations must be conducted in sustainable, economically feasible and socially acceptable manner (FRANKS et al., 2011FRANKS, D. M. et al. Sustainable Development Principles For the Disposal of Mining and Mineral Processing Wastes. Resources Policy, v. 36, p. 114-122, 2011.). Waste management technologies that offer improved environmental and social performance should be preferentially adopted; including opportunities for the reuse of tailings (EDRAKI et al., 2014EDRAKI, M. et al. Designing Mine Tailings For Better Environmental, Social and Economic Outcomes: a rewiew of alternative approaches. Journal of Cleaner Production, v. 84, p. 411-420, 1 Dec. 2014.).
The use of tailings in construction materials implies in a significant reduction in the overall carbon footprint of a building; it also mitigates the consumption of natural resources and the impacts associated with their production (PAPPU; SAXENA; ASOLEKAR, 2007PAPPU, A.; SAXENA, M.; ASOLEKAR, S. R. Solid Wastes Generation in India and Their Recycling Potential in Building Materials. Building and Environmental, v. 42, p. 2311-2320, 2007.; PASSUELO et al., 2014PASSUELLO, A. C. B. et al.Aplicação da Avaliação do Ciclo de Vida na Análise de Impactos Ambientais de Materiais de Construção Inovadores: estudo de caso da pegada de carbono de clíqueres alternativos. Ambiente Construído, Porto Alegre, v. 14, n. 4, p. 7-20, out./dez. 2014.). In this sense, as examples, Fontes et al. (2016)FONTES, W. C. et al.Mortars For Laying and Coating Produced With Iron Ore Tailings From Tailing Dams. Construction and Building Materials, v. 112, 2016., Shettimma et al. (2016)SHETTIMA, A. U. et al. Evaluation of Iron Ore Tailing as Replacement For Fine Aggregate in Concrete. Construction and Building Materials, v. 120, p. 72-79, 2016., Zhao, Fan and Sun (2016)ZHAO, S.; FAN, J.; SUN, W. Utilization of Iron ore Tailings as Fine Aggregate in Ultra-High Performance Concrete. Construction and Building Materials, v. 50, p. 540-548, 2016., Ma et al. (2016)MA, B. G. et al. Utilization of Iron Tailings as Subtitute in Autoclaved Aerated Concrete: physico-mechanical and microstructure of hydration products. Journal of Cleaner Production, v. 127, p. 162-171, 2016. and Yellishetty et al. (2008)YELLISHETTY, M. et al. Reuse of Iron Ore Mineral Wastes in Civil Engineering Constructions: a case study. Resources,Conservation and Recycling, v. 52, p. 1283-1289, 2008. have successfully used it as aggregate; Pereira and Bernardin (2012)PEREIRA, O. C.; BERNARDIN, A. M. Ceramic Colorant Form Untreated Iron Ore Residue. Journal of Hazardous Materials, v. 233-234, p. 103-111, 2012. as colorant; Duan et al. (2016)DUAN, P. et al. Fresh Properties, Compressive Strength and Microstructure of Fly Ash Geopolymer Paste Blended With Iron Ore Tailing Under Thermal Cycle. Construction and Building Materials, v. 118, p. 76-88, 2016., Cheng et al. (2016)CHENG, Y. et al. Test Research on the Effects of Mechanochemically Activated Iron Tailings on the Compressive Strength of Concrete. Construction an Building Materials, v. 118, p. 164-170, 2016. as geopolymer and binder. Iron ore tailings are mainly composed by iron oxides, silica and alumina, resulting in a fine, dense, stable and crystalline material (BASTOS et al., 2016BASTOS, L. A. C. et al. Using Iron Ore Tailings From Tailing Dams as Road Material. Journalof Materials in Civil Engineering, Ouro Preto, v. 28, n. 10, 2016.), technically feasible to be employed in civil construction.
Regarding its behaviour on the cement matrix, in a previous work, Fontes et al. (2016)FONTES, W. C. et al.Mortars For Laying and Coating Produced With Iron Ore Tailings From Tailing Dams. Construction and Building Materials, v. 112, 2016., tested mortars comprising IOT in full replacement of natural aggregates. The mortars with IOT reached compressive and flexural strengths superior than the conventional ones. In a similar work, matrices developed by Sant'Ana Filho et al. (2016)SANT'ANA FILHO, J. N. et al. Technical and Environmental Feasibility of Interlocking Concrete Pavers with Iron Ore Tailings from Tailings Dams. Journal of Materials in Civil Engineering, v. 29, n. 9, p. 04017104, 2016., with replacement of fine aggregate by IOT in proportions up to 80%, showed lower water absorption and more resistance to abrasion than their conventional counterparts.
Therefore, in order to contribute to the reduction of the environmental and social impacts of the disposal of IOT, the present work proposes a novel application for it - as both aggregate and pigment in sustainable cement tiles (SCT).
Cement tiles are cement-based composite plates with high abrasion resistance used in walls and floors, indoor and outdoor. They have a flat surface, textured or embossed, coloured or not, and are usually square shaped (ASSOCIAÇÃO…, 2010ASSOCIAÇÃO BRASILEIRA DE CIMENTO PORTLAND. Cement Tile Manual: public sidewalk. São Paulo, 2010.).
Historically, by the fourth century, the tiles were made up of pieces of coloured stones, with symbolic function to express the art and religion of the territories dominated by the Byzantine Empire (WAMZER, 2011WAMZER, R. L. K. The Cement Tile in Interface With art and Design in Mato Grosso. Universidade Federal do Mato Grosso (Masters Thesis). Cuiabá, 2011.). From the second half of the nineteenth century on, the composition of the tiles evolved to Portland cement composites, pressed, dried and cured by immersion in water (WAMZER, 2011WAMZER, R. L. K. The Cement Tile in Interface With art and Design in Mato Grosso. Universidade Federal do Mato Grosso (Masters Thesis). Cuiabá, 2011.). This new constitution contributed to the technological gain of the cement tiles, hence motivating its large-scale adoption around the world.
Unvalued around the 1950s, due to competition with ceramic tiles, since 1980, architects, designers and decorators have begun again to appreciate coatings with cement tiles (CATOIA, 2007CATOIA, T. High Performance Hydaulic Tiles and Coverings. 133 p. Universidade de São Paulo (Master Thesis) São Carlos. 2007.). This is a reflex of the current trend to seek traces of memory in the past, in order to enhance value through intangible aspects such as nostalgia and emotion. The revival of cement tiles allowed for customized designs, and for creating composition with other materials (CATOIA, 2007CATOIA, T. High Performance Hydaulic Tiles and Coverings. 133 p. Universidade de São Paulo (Master Thesis) São Carlos. 2007.).
A cement tile is divided in two layers. The wear/colour layer, in the surface, is approximately 3-5mm thick, and comprises a fine mixture of white cement (WC), crushed white marble (CWM) or fine sand (0.075 to 0.6 mm) and conventional pigments (CP). The quality of this layer provides the abrasion resistance, the colour and brightness of the tile. The base layer, approximately 20mm thick, consists of a mortar of cement and medium sand (0.6 to 1.18 mm), and provides the mechanical strength. Both layers are compressed into one single tile by a specific set of moulds and a hydraulic press.
The manufacture of cement tiles in Brazil is mostly scattered among craft shops in the Southeast region, where most of the population - and tailings dams - are located. The initial investment is relatively low, as is the producer's educational requirements. The incorporation of IOT does not require adaptation in the production method, based on manual hydraulic press; that is, no energy is required for either acquiring equipment or operating it.
To achieve a good relationship between product and user, the study of interfaces is critical to the market. It involves a value analysis through the integration of technical, production, and administrative sectors, as well as environmental, social and emotional factors. Therefore, by incorporating intangible attributes, the development of more effective products is attained - that is - products that meet the intended use, as well as other consumer's expectations (GONTIJO, 2008GONTIJO, L. A. Complexity and Interdisciplinarity in Interface Design. Advanced Studies in Design: Transversality, v. 1, n. n. 2, p. 79-90, 2008.).
Value analysis
Value Analysis consists in the representation of technological evolution, given its approach from the birth of a need to its final conception (VARGAS, 2013VARGAS, R. V. Earned Value Analysis. Brasport, n. 6, p. 144, 2013.; PEREIRA FILHO, 1994PEREIRA FILHO, R. R. Value Analysis: continuos improvement process. São Paulo: Nobel, 1994.). It is a systematic application of techniques to identify the main aspects of a product or a component and to provide the desired function at the minimum cost. Consequently, it enables analysing the return on investment of a new product and thus allows for the decision to whether continue the project or not. Within the economic sphere, the real value of a product, process or system comprises the combination of specific values and represents the degree of acceptance by the customer, directly depending on local and temporal conditions (VARGAS, 2013VARGAS, R. V. Earned Value Analysis. Brasport, n. 6, p. 144, 2013.).
Regarding the Methodology of Value (CSILLAG, 1995CSILLAG, J. M. Value Analysis. São Paulo: Atlas, 1995. ), the economic value is divided in:
use value (Vu): monetary measure of the qualities related to the performance of use;
esteem value (Ve): monetary measure of the properties that make its possession desirable;
cost value (Vc): monetary measure to produce or obtain a product; and
exchange value (Vx): monetary measure that enables the exchange for other goods.
Based on the values described, there are two ways of analysing the exchange value of a product. For the consumer, by adding the values of use and esteem (Eq. 1):
Eq. 1 Vx = Vu + Ve
For the producer, as the sum of the cost and a differential (ΔV), considered the profit (Eq. 2):
Eq. 2 Vx = Vc + Δ V
Therefore, combining both equations (Eq. 3):
Eq. 3 Vu + Ve = Vc + Δ V
Through this relationship, it is possible to infer that the higher the use value (Vu) and esteem (Ve) and the lower the cost value (Vc), the greater the profit made on a product (ΔV).
Emotional/Esteem Value
Emotion is closely linked to the relationship that people have with a product. Jordan (1999)JORDAN, P. Inclusive Design. In: GREEN, W. S.; JORDAN, P. W. (Eds.). Human Factors in Product Design: current practice and future trends. London: CRC Press, 1999. presented a hierarchy of needs, considering that people demonstrate their experience with the product when they relate to it. This experience covers aspects of utility, functionality, ease of use, as well as sensory conceptions, as shown in Figure 1.
Hierarchy of the user's needs for products
Figure 1 shows the pleasure at the top of the hierarchy of needs, representing the degree of pleasantness of people in interaction with objects. Therefore, when dealing with product design, the engineer/architect/designer can start by specifying the desired emotion as a result, such as social expression, environmental ideology, nostalgia, or sensory pleasures. Only then the professional evaluates the usability parameters, technical and safety aspects, considering whether it meets the required performance.
The esteem value of a product can be established by features that confer it beauty, prestige and admiration considering its aesthetic values, as well as connection and affection towards their symbolic values.
For a better understanding of the esteem value it is necessary to subdivide it in aesthetic value and symbolic value. The aesthetic value is related to the semantics of the product, which consists of a suitable visual appearance its function. Thus, with respect to colours, shapes, textures and backgrounds, which include automatic emotional responses related to the first contact with the product (CREUSEN; SCHOORMANS, 2005CREUSEN, M. E.; SCHOORMANS, J. P. The Diferent Roles of Product Appearance in Consumer Choice. Journal of Product Innovation Management, v. 22, n. 1, p. 63-81, 2005.). According to Kissmetrics (2010)KISSMETRICS, B. How Do Colors Affect Purchases? 2010. Available: <https://blog.kissmetrics.com/colors-psycology/>. Access: 22 June 2016.
https://blog.kissmetrics.com/colors-psyc... , 93% of consumers consider the appearance of the goods when shopping and 85% say the colour is the main reason they purchase a particular product.
In turn, the symbolic value of a product comprises the conception of memory and self-image, based on intrinsic and social values of each person (MIRANDA; CÂMARA, 2010MIRANDA, C. A.; CÂMARA, J. J. D. Origin, Culture and Value Analysis in Design of Products From Plastic Bottles. In: BRAZILIAN CONGRESS OF RESEARCH AND DEVELOPMENT DESIGN, 9., 2010. Proceedings… 2010.). Therefore, the symbolic functions are associated with sociocultural relations, obtained through the social, historical and technological context of a country or region.
The reaffirmation of the local identity in products, to the extent that it establishes links and connections, creates a benchmark of authenticity in the midst of mass production and homogeneity that have prevailed since globalization. In this sense, one must unite characteristic elements of a culture: i.e. the fauna, flora, architecture, topography, religion, among others (MORAES, 2008MORAES, D. Design and Complexity. Advanced Studies in Design: Transversality, v. 1, n.2, p. 7-23, 2008.).
In this sense, one notable example is the Lucky Iron Fish ™. In order to provide dietary supplementation of iron to underprivileged families affected by iron-deficiency anaemia in Cambodia, a group of researchers distributed a rectangular iron bar for cooking. However, the women were reluctant to use the chunk of iron in the cooking pan. The solution came through design enhancement: the previous iron bars were replaced by fish-shaped iron ingots, which carry strong cultural and historical bonds to the population. As a result, the iron fish were received more positively by the villagers and led to immediate increases in blood iron levels among them. In addition, the iron fish are cast from recycled metal, and employ the Cambodian community in the production line. Since the beginning of this project, the research group has delivered over 82,000 iron fish around the world (LUCKY…, 2016LUCKY IRON FISH. About Us. 2016. Available: <http://www.luckyironfish.com/about-us>. Access: 22 June 2016.
http://www.luckyironfish.com/about-us... ).
According to the Brazilian Institute of Mining (INSTITUTO…, 2013INSTITUTO BRASILEIRO DE MUSEUS. Management for Sustainability in Mining: 20 years of history. Brasília, 2013.), the strengthening of accountability and transparency is directly related to understanding of the mining industry's contributions to the development of the country. According to a research conducted by the Ethos Corporate Social Responsibility Indicators concerning the perception of Brazilian consumers, 86% of respondents would increase their respect for a company if it became partner of a non-governmental organization or charity institution, with the purpose of solving social problems (RUSCHEL; ROSE, 2005RUSCHEL, R. R.; ROSE, R. E. The Path of Sustainable Development: the memory of the first 5 years of the Von Martius Environmental Award. AHK, Câmara Brasil Alemanha, 2005.).
Therefore, the structure of the economy attributes a particular social role to goods. It is believed that the product carries an inexplicable power over the buyer, in order to satisfy their desires for attraction, ideology, identity, social expression, among others (LEDOUX, 1998LEDOUX, J. The Emotional Brain: the mysterious underpinnings of emotional life. Simon and Schuster, 1998.).
Environmental value
Since the 1980s, intangible aspects such as image and corporate culture of companies have become their greatest asset (ESTY; WINSTON, 2009ESTY, D.; WINSTON, A. Green to Gold: how smart companies use environmental strategy to innovate, create value, and build competitive advantage. New York: John Wiley & Sons, 2009.). According to Willard (2002)WILLARD, B. The Sustainability Advantage: sever business case benefits of a triple bottom line.[S.l.]: New Society Publishers, 2002., a company, when employing principles of social and environmental sustainability, has the potential to increase profits by up to 38%, its market value by 12% and productivity by up to 8%, due to the reduction of production costs and expenses, such as energy, water, raw materials, among others
In this scenario, customer demand for sustainable construction materials has also been boosted due to greater environmental awareness. Increased recognition of climate change is changing priorities as people remodel the way they live to reduce the impacts of their daily life on the environment. In fact, customers are seeking innovative solutions that would improve their quality of life, reduce their energy-related costs, while being environmentally-friendly (OBSERVATORY, 2014OBSERVATORY, B. I. Smart Living: advanced building materials. European Union, 2014.).
In conclusion, an investment in the intangibility of the product, i.e. the adoption of factors such as novelty and sustainability, is directly related to improvement in the tangibility of sales. In this sense, this work evaluates both the technical and intangible aspects of a SCT produced with IOT, aiming to develop the best possible building solution regarding design and material. Therefore, we seek to obtain an economically feasible product, while contributing to the reduction of the social and environmental impact of tailings dams.
Initially, an experimental program was undertaken to evaluate the technical and environmental feasibility of the use of IOT as aggregate and pigment in the production of SCT. Secondly, an empathy map was drawn based on the profile of one professional in interior design and one potential consumer seeking to identify all significant variables in the value analysis. Finally, an exploratory investigation was conducted to identify and apply intangible value on this product. Intangible aspects of this product were assessed through strategies proposed by the service design, in environmental, social and emotional levels. As a result of these studies, the SCT was developed.
Technical feasibility
The proposed product is a sustainable cement tile (SCT), intended for use as floor tile, indoors and outdoors. In this work, IOT was employed as aggregate in the base layer and pigment in the colour layer. The physical characterisation of IOT, CWM and sand comprised: particle size distribution by sieving and laser diffraction (Bettersize 2000 equipment), bulk specific gravity and apparent specific gravity. Tests were performed according to Brazilian standards NBR 7217 (ABNT, 1987ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7217: aggregates: determination of particle size distribution. Rio de Janeiro, 1987.), NBR NM 45 (ABNT, 2006ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR NM 45: aggregates: determination of the unit weight and air-void contents. Rio de Janeiro, 2006.) and NBR NM 53 (ABNT, 2003ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR NM 53: coarse aggregate: determination of the bulk specific gravity, apparent specific gravity and water absorption. Rio de Janeiro, 2003.).
A Coleman Optical Microscope and a Scanning Electron Microscope (SEM), were used to investigate the microstructure of the tailings. Experiments and analyses involving electron microscopy were performed in the Nanolab Electronic Microscopy Laboratory, at the Redemat, UFOP; and the Materials Characterisation Laboratory, at CEFET, MG, Brazil.
Chemical characterization was carried out by a semi-quantitative energy dispersive X-ray fluorescence (XRF) in a PANalytical Epsilon 3X equipment. The DRX was carried out on a D2 PHASER from Bruker at Nanolab, Redemat, Federal University of OuroPreto. The equipment operated with CuKa radiation, 30 kV tension, 30 mA current intensity, angular velocity equal to 0.02 º, 0.8-second step, and angular range between 5º and 70º. The analysis and refinement of results were performed using the Rietveld method, on aX'Pert High Score Plus Panalytical software, aided by the Crystallography Open Database (COD) database of crystal structures. Fluorite (CaF2), brand VETEC, was used as internal standard, added in proportion of 10% to the IOT mass. The samples were weighed to a precision of four decimal places and homogenized in porcelain mortar.
According to the Brazilian standard, NBR 7211 (ABNT, 2009ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7211: aggregates: specification. Rio de Janeiro, 2009.), the aggregate for cement-based composites must be an inorganic, crystalline and stable material. They must not present hazardous chemical substances, such as chlorites and sulphates (in concentrations above 0.2% and 0.1% respectively), or substances that may affect the hydration of the cement (ABNT, 2009ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7211: aggregates: specification. Rio de Janeiro, 2009.). Preferably, they must attend to optimum particle size distribution zones, i.e. the maximum content of material passing the #8 sieve (2.36 mm) must fall between 10% and 20% (ABNT, 2009ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7211: aggregates: specification. Rio de Janeiro, 2009.). However, the standard states that materials with different particle size distributions may still be used, given that their applicability is proven. This is achieved by the morphological and chemical analysis.
Environmental feasibility
Leaching and dissolution tests were performed to assess the level of contamination of the elements in the sample, according to standards NBR 10005 (ABNT, 2004aASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 10005: procedure for obtention leaching extract of solid wastes. Rio de Janeiro, 2004a.) and NBR 10006 (ABNT, 2004bASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 10006: procedure for obtention of solubilized extraction of solid wastes. Rio de Janeiro, 2004b.). These tests seek to reproduce the natural phenomena of carrier, dilution and dissolution that occur when water passes through a residue.
For the leaching test, the Brazilian Standard prescribes the jar-test equipment for continuous stirring; no definite speed; and waste/deionised water ratio of 1:16. This standard uses 0.5N acetic acid as pH control (pH = 5). In turn, the dissolution test uses a waste/deionised water ratio of 4:1; 5-min stir; and 7-day rest. The leached and solubilised extracts are filtered in a 0.45 µm porous media. Subsequently, they are chemically analysed to identify several toxic organic and inorganic compounds.
According to the concentration of the substances in the leachate and solubilised extracts, the residue is classified, following the prescribed limits in standard NBR 10004 (ABNT, 2004cASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 10004: solid waste: classification. Rio de Janeiro. 2004c.). Solid materials can be classified according to NBR 10004 (ABNT, 2004cASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 10004: solid waste: classification. Rio de Janeiro. 2004c.) as Class I - dangerous, or Class II - non-dangerous. In addition, Class II is divided into Class II-A: non-inert and Class II-B: inert. In total, the tests evaluate 35 parameters, such as the pH, the concentration of arsenic, barium, cadmium, lead, sulphates, mercury, organic compounds, among others. The classification is based on the parameters that the samples exceed the stipulated limits.
Feasibility as pigment
The inorganic pigments used in cement tiles are fine particles, generally insoluble in water (LEE; LEE; YU, 2003LEE, H. S.; LEE, J. Y.; YU, M. Y. Influence of Iron Oxide Pigments on the Properties of Concrete Interlocking Blocks. Cement and Concrete Research, v. 33, n. 11, p. 1889-1896, 2003.). They are usually comprised of iron oxide and chromium oxide; with proportions that vary according to the desired colour. In order to produce stable and aesthetically pleasing pigments, IOT was employed in 2 forms: in natura and fired. In both cases, the materials were oven-dried.
To obtain the fired IOT, the waste was initially segregated in its main components: iron ore, sand and clay; through a process performed by an outsourced company. This process involves drying, milling, density separation and magnetic separation without the use of water (PEIXOTO; BARROS; OLIVEIRA, 2014PEIXOTO, R. A. F.; BARROS, J. B.; OLIVEIRA, J. R. Processo de Extração de Argila, Sílica e Minério de Ferro Através de Concentração a Seco. Patent Pending - BR 10 2014 002076 4, 2014.). It should also be noted that the segregation process makes it possible to recover iron ore from IOT, a material of greater economic interest.
The clay fraction was adopted in the present work. This fraction contains a higher concentration of iron oxide in the hematite and goethite phases than the raw IOT (ANDRADE, 2014ANDRADE, L. C. R. Characterization of Iron Mining Tailings, in Natura and Segregated, For Use as Construction Material. Universidade Federal de Viçosa, (Doctoral dissertation), Viçosa, 2014.). Furthermore, the sinter and calcination processes promote the conversion of goethite into hematite by dehydroxylation and, consequently, improves the pigmentation capacity of the material (TAVARES, 2012TAVARES, P. H. C. P. Obtenção de Pigmentos de Óxido de Ferro a Partir da Lama Gerada no Beneficiamento de Itabirito. Ouro Preto, 2012. PhD Thesis - Universidade Federal de Ouro Preto, Ouro Preto, 2012.). For the preparation of the pigment, the clay from the IOT was fired at 950 ºC for 120 min in a muffle furnace (brand Jung JB3013), with temperature step of 3 ºC/min. Subsequently, it was grinded in a planetary ball mill (brand Retsch PM 100) for 10 min in rotation of 400 rpm. This fraction was adopted as pigment (P-IOT).
The SCT were fabricated according to the conventional technique called "Pastinha", which refers to the high fluidity of the mortar in the colour layer. Specimens 5×5×2 cm were moulded in proportions 2:1 - white cement (WC):aggregate in mass (Figure 2). Two types of aggregate were used: crushed white marble (CWM) and IOT in natura. On specimens with only CWM, contents of 5% and 10% of pigments were added - conventional and P-IOT. The conventional pigment (CP) is a brown inorganic synthetic material suitable for use in cement-based composites, produced by Lanxess and purchased directly on the market.
Sample of the colour layer with IOT as aggregate, for pigment evaluation
In all mixtures, 70ml of water was used (water/cement factor of 0.7). In total, nine mixtures were proposed using WC, CWM, CP, IOT and C-IOT both as aggregate and pigment, as shown in Table 1. Mixtures T10 and T11 are dual colour, T1+T4 and T1+T8 respectively, developed seeking to access the possible mixing of colours.
Mixtures developed for the colour layer
The colour range, surface quality and proportion of IOT as pigment were evaluated through visual inspection. As prescribed by Brazilian standard for cement tiles, NBR 9457 (ABNT, 2013ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 9457: hydraulic tiles to paving: specification and test methods. Rio de Janeiro, 2013.), the material must present aspects such as homogeneity of colour, sharp edges, no cracks, visible burrs or flaws.
According to the Methodology of Value (CSILLAG, 1995CSILLAG, J. M. Value Analysis. São Paulo: Atlas, 1995. ), when considering the use of IOT in the production of SCT, it is assumed to generate an increase in the profit of the product. This is achieved by reducing the cost, due to the replacement of natural aggregate by the recycled one, IOT, and increasing the esteem value. The SCT's emotional/esteem value is related to the historical, architectural and artistic values of cement tiles, as well as the satisfaction provided to the consumer, who, when acquiring the product, contributes to the recycling of waste. On the assumption that the replacement of natural aggregate by IOT does not change the value in use of SCT, i.e. they have compatible technical aspects, we can summarize these considerations in the following equation:
Eq. 4 Δ V = Ve − Vc
That is, reducing the cost of production and/or increasing the esteem value of cement tiles lead to higher profits.
Epathymap
The Empathy Map assists on the understanding of the environment, behaviour, concerns, and aspirations that affect the users of a product (TSCHIMMEL, 2012TSCHIMMEL, K. Design Thinking as an Effective Toolkit for Innovation. In: ISPIM, 23., Barcelona, 2012. Proceedings… Barcelona, 2012.). This method assists the design process based on the client perspectives, through a defined template and guide questions, displayed in Table 2 (OSTERWALDER; PIGNEUR, 2013OSTERWALDER, A.; PIGNEUR, Y. Business Model Generation. São Paulo: Alta Books, 2013.). The empathy map in the present work was drawn based on personas representing one professional in interior design and one potential consumer. These hypothetical archetypes of real users were evaluated in order to identify influences, needs, emotions and fears, related to the context of the SCT (FERREIRA et al., 2015FERREIRA, B. M. et al. Designing Personas With Empathy Map. In: INTERNATIONAL CONFERENCE ON SOFTWARE ENGINEERING AND KNOWLEDGE ENGINEERING, Pittsburgh, 2015. Proceedings… Pittsburgh, 2015.; ACUÑA; CASTRO; JURISTO, 2012ACUÑA, S. T.; CASTRO, J. W.; JURISTO, N. A HCI Technique For Improving Requirementes Elicitation. Information and Software Technology, v. 54, n. 12, p. 1357-1375, 2012.). This tool has obtained excellent results in product development processes (RIBEIRO; SOUZA, 2014RIBEIRO, T.; SOUZA, P. A Study on the Use of Personas as an Usability Evaluation Method. In: INTERNATIONAL CONFENRENCE ON ENTERPRISE INFORMATION SYSTEMS, 16., Lisbon, 2014. Proceedings… Lisbon, 2014.). In the present work, the user modelling technique served as a guide to understanding the intangible values associated with the SCT, through ideological mapping of feelings, thoughts, concerns and aspirations of potential consumers for the product.
Questions for developing the empathy map
By relating the results of the Empathy Map, the colour range of IOT and a thorough investigation of the history of cement tiles, four design proposals were developed. They embrace shape, colour palette and illustration of the colour layer, seeking to incorporate value and to facilitate incorporation in the market.
According to Brazilian standard NBR 9457 (ABNT, 2013ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 9457: hydraulic tiles to paving: specification and test methods. Rio de Janeiro, 2013.), aggregates for cement tiles may be natural, industrial or recycled. Therefore, the use of IOT as recycled aggregate is within the prescriptions of the standard.
Figure 3 shows the particle size distribution of the materials. The characteristic dimensions, D10, D50 e D90 can be seen in Table 3 (where DN corresponds to the diameter of the sieve, in mm, above which N% passed). It is noticeable that the CP is a particularly fine material, with 90% of its particles smaller than 8 µm. It is followed by the P-IOT, with 90% of the material smaller than 0.06 mm; IOT (0.17 mm); CWM (0.7 mm), and natural fine aggregate, river sand, with D90 of 1.8 mm.
Particle size distribution of the materials
Characteristic dimensions of the materials
The particle size distributions of IOT and CWM are not within the optimum limits of aggregates for cement-base composites prescribed by Brazilian standard NBR 7211 (ABNT, 2009ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7211: aggregates: specification. Rio de Janeiro, 2009.), due to their fineness. The small particle size distribution of the IOT may lead to an increase of the amount of water to obtain workability for the matrix, as is commonly observed for conventional pigments (BRUCE; ROWE, 1992BRUCE, S. M.; ROWE, G. H. The Influence of Pigments on Mix Designs For Block Paving Units. In: INTERNATIONAL CONFERENCE OF CONCRETE BLOCK PAVING, Auckland, 1992. Proceedings… Auckland, 1992.). This effect will be probably more significant for CP. On the other hand, the fineness of the IOT enables it to be used as both pigment and filler on the colour layer, thus reducing the pores and enhancing its aesthetic aspects.
Concerning the microstructure (Figure 4 to Figure 8 the CP SEM predominantly presents fine, sub-rounded and tabular particles. Most of the P-IOT grains, both large and small, are also sub-rounded, due to the burning process. In the analysis, IOT particles show an irregular morphology, with a large amount of fines. Furthermore, as confirmed by the particle size distribution of the materials, river sand and CWM presented relatively larger particles, with the CWM ones slightly more angular than the others, due to its obtaining process.
SEM of CP particles (20,000x)
SEM of P-IOT particles (20,000x)
SEM of IOT particles - 500x
SEM of CWM particles - 200x
SEM of River Sand particles - 500x
Table 4 shows the physical characterisation of the aggregates and mineral admixtures used in the present work, while Table 5 shows their chemical characterisation. It is observable that the natural aggregate, river sand, showed lower bulk and apparent density when compared to the other aggregates. This is due to their chemical composition.
Physical Characterisation of the materials
Chemical characterisation of the Materials
Regarding the XRF, it is shown that river sand is mainly comprised by silicon and aluminium oxides; iron and silicon oxides are the predominant components of IOT, while calcium and magnesium oxides are the major constituents of CWM.
Figure 9 shows the diffractogram of the IOT sample, with the main components highlighted in the curves: quartz, hematite and kaolinite. Therefore, the XRF and DRF analysis combined showed no deleterious or expansive substances in significant concentration, such as chlorites and sulphates (ABNT, 2009ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7211: aggregates: specification. Rio de Janeiro, 2009.).
DRX diffractogram of IOT
As a result of the physical and chemical characterisation, the IOT is an inorganic, crystalline, innocuous and stable material, and thus a suitable aggregate for cement-based composites, according to the Brazilian standard NBR 7211 (ABNT, 2009ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7211: aggregates: specification. Rio de Janeiro, 2009.). In addition, its fineness improves its usability as pigment and filler in the colour and base layers of the SCT.
The leaching and dissolution analyses performed for the IOT confirm their environmental feasibility. The results for the dissolution parameters that exceeded the normative requirement are presented in Table 6. For the leaching test, the IOT presented all results within the standard limits. According to the prescriptions of standard NBR 10004 (ABNT, 2004cASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 10004: solid waste: classification. Rio de Janeiro. 2004c.), the samples were classified as Class II A, non-dangerous and non-inert. Thus, it does not present hazardous characteristics such as corrosivity, reactivity, toxicity, pathogenicity or flammability (ABNT, 2004cASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 10004: solid waste: classification. Rio de Janeiro. 2004c.).
Dissolution results for the raw IOT that exceeded the standard requirements
The colour layer compositions, with IOT and conventional, are shown in Figure 10. The specimens showed a comprehensive variety of tones, sharp edges and a homogeneous surface - no cracks, burrs or flaws were observed. This appearance is in accordance with the visual inspection prescribed by standard (ABNT, 2013ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 9457: hydraulic tiles to paving: specification and test methods. Rio de Janeiro, 2013.).
Colour layer mixtures: T1, T2 and T3 comprise 0%, 25% and 50% of IOT as aggregate; in T4 and T5 use CP as pigment, T6 and T7, IOT and T8 and T9, P-IOT; finally, T10 and T11 present double colours with CP and P-IOT respectively
In mixtures T1, T2 and T3, with increase in content of IOT as aggregate, a darker reddish/brownish tone was achieved (Figure 10a). In mixtures T6 and T7 (Figure 10b), in comparison with the same content of conventional colorant - T4 and T5 - the IOT showed slightly lower pigment properties. Mixtures with P-IOT, T8 and T9, showed better performance than those with the in natura IOT, but with colours not as dark as the ones with CP. These observations are related to the lower iron content in the IOT than in the CP. However, the lightness of tones be corrected, if wished, with an increase in IOT content, which is also more sustainable. The ones with double colours showed overall good contrast and did not present mixing, as shown in Figure 10c. Mixtures with IOT, as shown on the left of Figure 11, presented less pores, with reduced size, in comparison with conventional ones, on Figure 11-right. This is a result of the filler effect of the IOT, as shown in its particle size distribution.
Surface of mixtures T5 (left) and T7 (right), magnification 10x
This result is in agreement with the works of Sant'Ana et al. (2016)SANT'ANA FILHO, J. N. et al. Technical and Environmental Feasibility of Interlocking Concrete Pavers with Iron Ore Tailings from Tailings Dams. Journal of Materials in Civil Engineering, v. 29, n. 9, p. 04017104, 2016., whose cement-based composites presented homogeneous colours and less pores than the conventional counterparts. In addition, the colour does not fade or stain, as observed in the work of Fontes et al. (2016)FONTES, W. C. et al.Mortars For Laying and Coating Produced With Iron Ore Tailings From Tailing Dams. Construction and Building Materials, v. 112, 2016., whose coating mortars were subjected to the outdoors environment for over 3 years and showed no alteration on their surface quality.
From the studies carried out, the design is presented as a fundamental tool in the conception of a link between product and user. Thus, Figures 12 and 13 seek to trace a consumer profile for the SCT, by considering the perspective of customers, fulfilling their needs.
Empathy Map of a persona of a SCT consumer: end user
Empathy Map of a persona of a SCT consumer: interior designer
Environmental, social and esteem assessments
In Brazil, the cement tile is responsible for creating new dimensions of the art, while acquiring national traits (WAMZER, 2011WAMZER, R. L. K. The Cement Tile in Interface With art and Design in Mato Grosso. Universidade Federal do Mato Grosso (Masters Thesis). Cuiabá, 2011.). Thus, it associated uniqueness, personal aspirations and experiences, which constituted an identity to the coating, instigating, therefore, memories and feelings in its users. Thus, this type of coating assumes an affective value able to provide well-being and pleasure when used. Furthermore, its craft process has survived in the midst of the mass-produced coatings industry.
As a result of the research, SCT prototype will be produced monochrome or coloured at up to five shades. Allied to the colours, the designs applied to the SCT will be traditional, like arabesques, floral and geometric shapes, inspired by elements that reflect local identity. Figure 14shows the surface design of the prototypes of the SCT, based on the value analysis.
Surface design of the prototypes of the SCT, based on the value analysis and colour palette
The proposed SCT will also use sustainability as an intangible asset, by employing a residue in its composition. The IOT will be employed as aggregate and filler, increasing the physical-mechanical performance of the base layer. Furthermore, it will also be used as colorant in the composition of earthy tones on the colour side.
Regarding the shape, SCT will adopt the most common option, with dimensions of 200 x 200 mm and thickness of 25 mm, for ease of insertion of the market. According to the results of Empathy Map, the SCT has the potential to cover both consumers with high income, seeking for social and environmental expression, as the low-income ones, due to nostalgia aspects.
Thus, this type of coating assumes an affective value able to provide well-being when used. Its craft process has survived in the midst of the mass-produced industry, promoting labour opportunities for community craftsmen, and strengthening of the culture and local economies. In this sense, the SCT will not only contribute to the reduction of the environmental impact of IOT, but also minimize the costs with raw material, promote new business opportunities for artisans, meet the sustainability agenda of companies, and ultimately improve the quality of the built environment.
According to the physical, chemical and morphological analysis, iron ore tailings (IOT) are a stable fine material. The environmental tests resulted in a non-dangerous classification, meaning that IOT do not present hazardous characteristics such as corrosivity, reactivity, toxicity, pathogenicity or flammability. Therefore, it is technically and environmentally suitable to be used as replacement of conventional colorant and crushed marble in the colour layer; and as replacement of sand and/or filler in the base layer. In this sense, IOT present a suitable alternative for the production of sustainable cement tiles, producing an aesthetically pleasing and potentially durable coating.
The design proposed for SCT meets the consumers' expectations regardingtheir desires for sustainability, ideology, social expression, nostalgia, among others. It does so by creating a product with local identity, incorporating residues in its manufacture, reducing the impacts of the disposal of IOT, promoting labour opportunities for artisans, strengthening local culture and overall improving the quality of the built environment.
Further investigation is required in order to evaluate the physical and mechanical properties of the Sustainable Cement Tile itself. However, this initial study concludes that the IOT is a technical, social and environmentally feasible alternative to the exploitation of natural resources in the production of cement-based composites. This reuse also contributes to the reduction of risks, and social and environmental impacts of tailings dams.
We gratefully acknowledge the agencies FAPEMIG, CNPq, CAPES, UFOP and Fundação Gorceix for providing financial support. We are also grateful for the infrastructure and collaboration of the Research Group on Solid Wastes - RECICLOS - CNPq.
The authors would like to acknowledge the Nanolab Electronic Microscopy Laboratory, at the Redemat, UFOP; the Department of Ceramic and Glass Engineering from Universidade de Aveiro and the Materials Characterisation Laboratory, at CEFET, MG, Brazil, for providing the equipment and technical support for electron microscopy.
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Universidade Federal de Ouro Preto Ouro Preto - MG - Brasil
Wanna Carvalho Fontes Programa de Pós-Graduação em Engenharia Civil | Universidade Federal de Ouro Preto | Campus Morro do Cruzeiro | Ouro Preto - MG - Brasil | CEP 35400-000 | Tel.: (31) 3559-1547 | E-mail: wannarquit@gmail.com
Faculdade Dom Luciano Mendes Mariana - MG - Brasil
Giovanni Gonçalves Fontes Programa de Pós-Graduação em História da Arte | Faculdade Dom Luciano Mendes | Rodovia dos Inconfidentes, Km 108, Mariana - MG - Brasil | CEP 35420-000 | Tel.: (31) 3558-1439 | E-mail: gigiogf@gmail.com
Ellen Cristine Pinto Costa Departamento de Arquitetura | Universidade Federal de Ouro Preto | Campus Morro do Cruzeiro | Ouro Preto - MG - Brasil | CEP 35400-000 | Tel.: (31) 3559-1484 | E-mail: ellencosta425@gmail.com
Julia Castro Mendes Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | Tel.: (31) 3559-1546 | E-mail: jcmendes.eng@gmail.com
Guilherme Jorge Brigolini Silva Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | E-mail: guilhermebrigolini@gmail.com
Ricardo André Fiorotti Peixoto Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | E-mail: ricardo.fiorotti@ufop.edu.br
Programa de Pós-Graduação em Engenharia Civil | Universidade Federal de Ouro Preto | Campus Morro do Cruzeiro | Ouro Preto - MG - Brasil | CEP 35400-000 | Tel.: (31) 3559-1547 | E-mail: wannarquit@gmail.com
Programa de Pós-Graduação em História da Arte | Faculdade Dom Luciano Mendes | Rodovia dos Inconfidentes, Km 108, Mariana - MG - Brasil | CEP 35420-000 | Tel.: (31) 3558-1439 | E-mail: gigiogf@gmail.com
Departamento de Arquitetura | Universidade Federal de Ouro Preto | Campus Morro do Cruzeiro | Ouro Preto - MG - Brasil | CEP 35400-000 | Tel.: (31) 3559-1484 | E-mail: ellencosta425@gmail.com
Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | Tel.: (31) 3559-1546 | E-mail: jcmendes.eng@gmail.com
Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | E-mail: guilhermebrigolini@gmail.com
Departamento de Engenharia Civil | Universidade Federal de Ouro Preto | E-mail: ricardo.fiorotti@ufop.edu.br
Figures | Tables | Formulas
Eq. 1
Figure 1 Hierarchy of the user's needs for products
Source: adapted from Jordan (1999)JORDAN, P. Inclusive Design. In: GREEN, W. S.; JORDAN, P. W. (Eds.). Human Factors in Product Design: current practice and future trends. London: CRC Press, 1999..
Figure 2 Sample of the colour layer with IOT as aggregate, for pigment evaluation
Figure 3 Particle size distribution of the materials
Figure 4 SEM of CP particles (20,000x)
Figure 5 SEM of P-IOT particles (20,000x)
Figure 6 SEM of IOT particles - 500x
Figure 7 SEM of CWM particles - 200x
Figure 8 SEM of River Sand particles - 500x
Figure 9 DRX diffractogram of IOT
Figure 10 Colour layer mixtures: T1, T2 and T3 comprise 0%, 25% and 50% of IOT as aggregate; in T4 and T5 use CP as pigment, T6 and T7, IOT and T8 and T9, P-IOT; finally, T10 and T11 present double colours with CP and P-IOT respectively
Figure 11 Surface of mixtures T5 (left) and T7 (right), magnification 10x
Figure 12 Empathy Map of a persona of a SCT consumer: end user
Figure 13 Empathy Map of a persona of a SCT consumer: interior designer
Figure 14 Surface design of the prototypes of the SCT, based on the value analysis and colour palette
Table 1 Mixtures developed for the colour layer
WC (g)
CWM (g)
CP (g)
IOT (g)
P-IOT (g)
T1 - CWM 100 50
T2 - 50% CWM + 50% IOT 100 25 25
T3 -IOT 100 50
T4 - CWM + 5% CP 100 50 5
T5 - CWM + 10% CP 100 50 10
T6 - CWM + 5% IOT 100 50 5
T7 - CWM + 10% IOT 100 50 10
T8 - CWM + 5% P-IOT 100 50 5
T9 - CWM + 10% P-IOT 100 50 10
Table 2 Questions for developing the empathy map
Guiding Questions
Do What is common for him/her to say?
How does s/he normally act?
What are his/her hobbies?
What does he like to say?
How is the world in which s/he lives?
What do people around him/her do?
Who are his/her friends?
What is popular in his daily life?
What people and ideas influence him/her?
What do the important people in his/her life say?
What are his/her favourite brands?
Who are his/her idols?
Think What are some important ideas that s/he thinks and does not say?
Feel How does s/he feel about life?
What bothers him/her lately? Why?
Pains What is s/he afraid of?
What are his/her frustrations?
What has disturbed him?
What would s/he like to change in his/her life?
Needs What does s/he need to feel better?
What is success? What does s/he want to achieve?
What has s/he done to be happy?
What would end his/her pain?
What are some of his/her dreams?
Source:Osterwalder and Pigneur (2013)OSTERWALDER, A.; PIGNEUR, Y. Business Model Generation. São Paulo: Alta Books, 2013.
Table 3 Characteristic dimensions of the materials
P-IOT
River Sand
D10 (mm) 0.0006 0.0003 0.0050 0.0300 0.3000
Table 4 Physical Characterisation of the materials
Bulk Density (kg/m3) 4.26 3.88 3.37 2.88 2.69
Apparent Density (kg/m3) 0.56 1.13 1.42 1.70 1.54
Table 5 Chemical characterisation of the Materials
CP (%)
P-IOT (%)
IOT (%)
CWM (%)
River Sand (%)
Fe2O3 92.2 66.6 49.0 0.2 4.7
SiO2 0.0 12.6 40.1 3.1 59.6
Al2O3 0.0 14.9 8.9 0.0 31.3
K2O 0.0 0.2 0.3 0.0 1.7
TiO2 0.0 0.8 0.0 0.0 1.2
SO3 0.5 0.3 0.1 1.0 1.0
CaO 4.3 0.0 0.0 63.8 0.5
MnO 2.5 0.3 0.1 0.0 0.1
MgO 0.0 3.6 0.4 31.8 0.0
ZnO 0.5 0.1 0.2 0.0 0.0
Others 0.1 0.0 0.0 0.1 0.1
Table 6 Dissolution results for the raw IOT that exceeded the standard requirements
Average concentration (mg/L)
Upper limit (mg/L)
Aluminum 0.38 0.2
Phenols 0.53 NA
Iron 1.038 0.3
Vx = Vu + Ve
Vx = Vc + Δ V
Vu + Ve = Vc + Δ V
Δ V = Ve − Vc
Associação Nacional de Tecnologia do Ambiente Construído - ANTAC Av. Osvaldo Aranha, 93, 3º andar, 90035-190 Porto Alegre/RS Brasil, Tel.: (55 51) 3308-4084, Fax: (55 51) 3308-4054 - Porto Alegre - RS - Brazil
E-mail: ambienteconstruido@ufrgs.br


Troy-Bilt came into being in 1937 and were the first mower manufacturers to completely revolutionize rototillers. They've been leaders in the industry over the past 79 years and their products are considered to be the benchmark of quality when it comes to garden tools by even other leading manufacturing companies. So, it should be no surprise that we found the best wide area walk behind mower is a Troy-Bilt: The WC33XP Wide Area Walk Behind Mower.
10 Is It Worth Buying?
Troy-Bilt has several yard-care products on offer across a wide range of areas, all made with cutting edge technology.
When looking at their wide range of products it is tough to pick just one that stands out, given the sheer variety of gardening-related innovations they have produced in their tools.
For this reason alone we believe the Troy-Bilt WC33 can truly fulfill all your lawncare needs when you need a wide area mower. However when you actually look at the specs and see what it can do for you to cut down on lawn cutting time and the hassle often associated with wide area mowers it becomes a no-brainer.
The Troy-Bilt WC33 has an impressive 420cc OHV engine that is powerful enough to handle all kinds of lawn and yard work.
It has an extra wide 33 inch dual-blade cutting deck which trims an impressively wide path.
It's not only powerful and delivers professional results on par with commercial machines twice it's price, but it also incredibly easy to use.
What's more it has zero turn maneuverability that is usually only found in expensive riding mowers.
The fuel capacity is enough to get you through any yard no matter how big; the Troy-Bilt WC33 has a massive 2 gallon fuel tank.
The trimming capacity of this four-wheeled mowing beast is more than enough to cover lawns and yards of all sizes.
This is a moderately priced beast, for its class, that promises to make mowing fun and easy as well as commercially viable.
The first thing you need to do is figure out what you want.
Although this may sound a little patronising you should be aware of the vast range of machines available.
There are all kinds of lawn mowers out there and it doesn't necessarily mean that the most equipped machine is the best one for you, or even the best one in it's class. In addition the highest priced model isn't always the best either!
So, be sure to identify a mower that is the best for your needs; in this case you need to be looking for the best of the wide cut walk behind mowers.
A well-established company will have a detailed presence online with a solid reputation. However, we find the best way to get a real feel for what a machine can and cannot do is to look at buyer reviews (as outlined below).
The length and breadth of your lawn is one of the most important factors to consider while choosing a lawn mower.
Every landscape has its own dimensional challenges and if your lawn is huge, you should go with a lawn mower that has a powerful engine and wide cutting deck.
Conventional suburban lawns are one thing, but what if your terrain is a bit more challenging?
If you reside on a hilly area then you need power as well as ease of maneuverability.
If there are various obstacles on your lawn mower such as tree roots or flower beds then you need a machine that has flexibility of movement.
Making sharp turns with a standard mower is less than ideal in rough terrain and really won't get the job done on lawns that resemble an obstacle course.
This is why we believe it pays to choose the Troy-Bilt WC33 for such environments since it has both power and zero-turn maneuverability making it possible to move in any direction without any real effort.
Finally, you need to look at the company warranty. A manufacturer with a good track record should be confident enough to offer at least a year's warranty.
Luckily, the Troy-Bilt offers a 3-year limited warranty on their WC33 Wide Cut Self-Propelled Mower. All details regarding the warranty can be read here.
The lawn mower market is flooded with all kinds of products and different varieties of machines.
But what makes the Troy-Bilt WC33 33 inch walk behind mower stand out above other wide are mowers?
This engine derives power from a 420cc in-house developed OHV Engine.
It has all the great properties of a OHV engine such as high-grade components, a powerful torque system, fuel efficiency, quiet operation, cooler operating temperatures and a longer life compared to other types of engines found in The WC33's competitors.
Even though this is a walk behind mower the beast of an engine it houses allows the WC33 to operate at 4 Forward speeds and the 420cc can even match that of an entry level riding mower.
The stable throttle-control, combined with a sturdy build, gives you a vibration-free state-of-the-art lawn mowing experience.
One of the most important features of the Troy-Bilt WC33 is it's ability to cut wide. This means it can cover more area than a standard walk behind and the impressive dimensions of its well-designed blades make it possible to cut more grass in a single swoop.
It also has zero turn capability meaning you can turn on a dime just like expensive riding mowers.
You will find several different wide area walk behind mowers on offer at various stores and online.
However almost all of the alternatives have a single blade inside, whereas the Troy-Bilt WC33 has a massively wide 33″ inch cutting deck that has not one, but two blades.
Another impressive cutting deck feature is it's maneuverability.
The mowing deck can be readjusted to accommodate any terrain; you can use the easy access Deck Height Lever to go from low to high.
We felt this particular aspect of our chosen Troy-Bilt wide area cut machine deserved to be highlighted as this component offers a lot of features compared to the WC33's nearest competitors.
When using a gas mower it is obviously important to know when your mower is running low on gas so the LCD screen shows just how much juice the tank has left.
The voltage indication light disappears after 5 seconds and you see an hourglass figure to let you know the number of hours left for mower operation.
While the engine is running, the mower operation time is constantly shown on the screen.
The LCD screen is coupled with a very smart feature which allows you to see all the maintenance requirements of your machine right on the screen.
You will be notified through the LCD if the oil needs to be changed and it flashes to indicate recorded hours after the end of a 50-hour operation to indicate a simple, quick service may be in order.
This and all other features are fully covered in the online operator's manual.
These are not the only features offered by this powerful wide area machine.
Variable throttle control makes it easy to control the machine's speed. It is super response. You put less pressure on your body, and especially your arms, by being able to regulate and change speed.
The machine comes with a 33″ dual blade cutting deck that cuts a wide path quickly and easily. This reduces the time it takes to do the job and also puts less pressure on you.
The machine comes with a rear wheel drive with N, R and 4 Forward speeds giving you more options than most other gas mowers. This makes the job fun and easy.
The mower has an hour meter that offers maintenance reminders. This way you know when it is time to clean your device, fill the oil or other standard tasks. This helps increase the overall life of the device and also takes the guesswork out of servicing times.
The WC33 has a 2 gallon clear-view gas tank – more than enough to accommodate your needs.
There are several accessories that you can attach to the Troy-Bilt WC33 to increase its functionality.
Accessories include the Walk-Behind Bagger and a Mulching Kit in addition to a grass bag that is sold separately.
There is also the Siphon Pump for Outdoor Power Equipment that you can use to safely transfer oil and gas from the tank to the container. This is really something you should get as it saves messy oil and gasoline spills and also stops and spillage drips getting on your lawn.
This machine is also easy to clean and comes complete with a hose to make the job a little easier.
In order to change the plugs it is best to use the company-issued Extended Spark Plug Wrenches as they can greatly help you to reach the recessed plugs.
Cutting Height Range 8 Settings from 1.25" – 3.5" 6 Settings from 1.25" – 3.75" 6 Settings from 1.25" – 3.75"
It is very important to service your mower at regular intervals if you want to keep it in top performance mode and to increase its lifespan.
Regularly servicing your mower also stops excessive devauation of your machine should you ever want to sell it in order to upgrade, perhaps to a zero turn riding mower.
Although Troy-Bilt ensure the WC33 comes with a three-year warranty, that doesn't mean you shouldn't give it a little extra care and TLC. Just regularly cleaning your mower can easily give you a few more years of usage.
It's also important to keep up regular maintenance if you want it to operate at a hundred percent efficiency.
Luckily though the Troy-Bilt WC33 is not high maintenance at all.
The operator's manual has all the usage and maintenance guidelines you need to keep the machine in top shape.
Troy-Bilt also offer a Spanish translation of the entire manual, from page 32 of the manual, to meet the needs of their growing spanish-speaking american consumers which we thought was a nice customer-service touch.
This isn't your average motor-based lawn mower; the WC33 has a powerful OHV 420cc engine that requires oil to keep the moving parts lubricated. Follow the recommended oil schedule given in the operator's manual and your engine will perform at its best for many years after your initial purchase.
When you're fueling it up, be careful of spillage.
We recommend that you go through the operator's manual thoroughly, not to mention the safety section as well.
Cleaning this powerful machine is also not a Herculean task at all unlike some other mowers. It is very easy to move and is light enough to clean without any trouble.
A number of parts are detachable making it easier for you to access all areas to make sure you keep the machine fully clean and free of debris. It's important to do so if you want your machinery to stay in a good condition.
The operator's manual also highlights the cleaning process showing you how to detach and reattach different components.
Troy-Bilt has been in business for more than 75 years and during that time they have perfected what they do. They have the experience and specialist knowledge to ensure your machine gets all the TLC it will ever need.
So we therefore recommend you to go for the official Troy-Bilt professional service centers if there is a need for repair.
However, if you need a part or accessory it is best to seek the cheapest option from online sources such as Amazon especially when initially buying the mower.
It's always a good idea to check the compatibility of accessories if you are buying them local, as using the wrong item can lead to unforeseen damage to the accessory, or more importantly, to your machine.
As with any purchase don't just go with the first seller you see and although buying local has some advantages it can cost considerably more than the alternatives.
Buying online is now are great way to secure the lowest price for large purchases such as large lawn mowers as the cost savings to vendors, who save money on overheads such as retail premises, is often passed on the customer.
We found the cheapest option is to buy the WC33 online ensuring the seller offers it with free shipping – this will give you subtsantial savings.
The Troy-Bilt Wide Area Walk Behind Mower WC33 has an all-star rating on Amazon and other vendor websites.
Customers have been most satisfied with its performance and as far as our investigation could uncover there have are absolutely no negative reviews at this time.
A common theme among users is the powerful engine. One reviewer called the WC33 a monster explaining that he found the experience of using the mower to be more than satisfactory.
One overly-excited owner claimed that he so excited to get his new WC33 that he not only mowed his own lawn but mowed his neighbours too. Although we are fairly sure you won't be that enthusiastic about your new purchase it does indicate that the tediousness of mowing is counteracted by the ease of use of this machine.
Even though the WC33 packs more than just a few pros it does have a few cons – or at least a few slight concerns for users.
Some recurring reservations revolve around specific controls not being in the most desirable place. However, as all users who complained about this particular issue wanted the controls in different places from each other it seems to be more a point of personal preference than a real problem.
When you use the machine you will find you have no trouble at all accessing any of the controls regardless of where you would like them located.
A particular five-star reviewer mentioned that he had been previously using a 16 year-old Troy-Bilt Mower without any problems but as he wanted to update he was going to stay with the same manufacturer.
Another reviewer who recently purchased the WC33 was truly excited about the height control handle and the various adjustable speeds.
All online customers seem to be happy with other aspects of the purchase as well. Customer service appears to be a big win for Troy-Bilt and their sellers. The company takes care of its buyers and is ever ready to answer all queries.
Most of the questions related to a product or company policies can be answered online. In addition to this, the company is quick in responding to emails and answering calls.
If you decide to take advantage of the savings you get online be sure to go with an authorized dealer or the established big online vendors such as Amazon who offer their own warranty on top of Troy-Bilts.
The Troy-Bilt WC33 is our recommendation for anyone who needs a wide area walk behind mower.
With the WC33 you're getting serious power under the hood. At 420cc this thing can overcome just about any lawn mowing challenge and rip through the toughest of terrain while leaving a smooth professional finish.
No-one wants to make long turns while mowing their lawn as they want a smooth seamless finish and this is where the zero-turn maneuverability of the WC33 shines.
The Troy-Bilt company is known for making powerful lawn mowers and this is one of the best they have to offer. There is over 75 years of engineering experience behind this product so there really is nothing missing from the WC33.
The Troy-Bilt WC33 is priced economically, and we believe that over the years this mower will keep its price better than most other mowers on the market – should you ever wish to sell it and upgrade.
Although you can seek a dealer locally you will make a considerable saving by buying this online and as mentioned earlier.
There really isn't much assembly required once it's shipped to your home. After a few minor attachments and plugins, you'll be ready to go and like us you'll be convinced this is the best wide are walk behind mower money can buy.


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Tactics to cover-up porn addiction
By Liz Walker	June 8, 2020 July 7th, 2020 Impacts of porn
Porn addiction doesn't exist! At least, that's the mantra of porn-harms science-deniers. In a frenzied attempt to cover up the harms of porn on the brain, a group of scientists are hell-bent on convincing people that porn addiction doesn't exist.
Scientists in white coats by YouthWellbeing
Known as "Real Your Brain on Porn", this group (or certain individuals who represent this group) go to great lengths to dismiss, minimise and publicly attack anyone who speaks up about the harms of porn. The name of this group sounds deceivingly similar to the world-renowned and well-respected "Your Brain on Porn" site, run by Gary Wilson. Gary was among the first to raise the alarm as to what regular porn use is doing to some brains in his 2012 TEDx talk, The Great Porn Experiment.
Needless to say, Gary has received nothing but what can only be described as relentless harassment from this group. Why? Because he highlights the science that affirms addiction and other porn-related harms, phenomena observed by researchers, clinicians and therapists all over the world. Gary has even found himself having to defend his Your Brain on Porn trademark from those who actively seek to undermine his contributions. Additionally, those who speak out against porn harms are being forced to defend themselves through costly, drawn-out lawsuits and other public or legal battles.
For the sake of staying on point, I won't detail the horrific antics because Gary has documented them here, here, here and here.
So is porn addiction real or not?
Given I'm not a neuroscientist or clinician, I will leave the explanation of what's going on with the brain to the experts.
In 2016, Paula Hall, a leading expert in the field of sex and porn addiction, states:
Sex addiction is a real problem, but professionals can't agree if addiction is the right name for it. Or if it should be called an impulse control disorder or hypersexuality or sexual compulsivity and a whole host of other names. And until we do get an accurate clinical diagnosis, chances are that doubts and misunderstandings will continue. But professionals do agree that more and more people are struggling with sexual behaviours that feel out of their control.
For most, that includes internet pornography, but for some, it's also cybersex, visiting sex workers, cruising, multiple affairs, dating sites. The type of behaviour is not what defines it as an addiction, but the dependency on it. When we talk about alcohol addiction, we don't differentiate between those who drink whiskey or beer or tequila. And alcohol addiction is defined as a dependency on alcohol to make life feel more manageable. And of course, there are lots of people who can drink alcohol recreationally—maybe even a little too much at times—but they don't become dependent on it. You know you're addicted to alcohol if it's causing significant problems in your life, but in spite of those problems, you still can't control your drinking or stop. And the same is true for those who become dependent on internet pornography or any other kind of sexual behaviour. The reason that many people prefer the name addiction, including myself, is because that's actually how people who struggle with this say that it feels. It feels like an addiction. There's also a growing body of research that is showing that compulsive pornography use impacts the brain in a very similar way to chemical dependencies … One only needs to read the comments from people at the bottom of Paula's TEDx talk to see how relieved people are to gain understanding about a range of behaviours under the banner of "sex addiction", of which, one is porn addiction.
When Dr Donald Hilton was asked in 2015, "Do you think porn addiction has been proven beyond doubt?", he responded by saying: To me, the proof has been there for several years.
This segment of the documentary, "Is free pornography destroying our brains?", is very good at explaining the science and what is going on for consumers.
Sex addiction and porn addiction are an outworking of compulsive sexual behaviour, often incorrectly presumed to result due to some form of underlying trauma. However, Dr Rob Weiss has the following to say:
"For a long time, therapists treating sex and porn addiction found that all (or at least the vast majority) of their clients had deep and powerful underlying early-life trauma issues—neglect, physical abuse, sexual abuse, covert incest, etc. This put sex and porn addicts very much in line with alcoholics, drug addicts, compulsive gamblers, and the like. In fact, there is a large body of research showing unresolved early-life trauma to be a huge risk factor for later-life addiction (of all types).
Recently, however, sexual disorders therapists like myself have encountered a new and rapidly growing subcategory of sex and porn addicts. These are individuals who readily meet the criteria for sex and porn addiction but lack the underlying early-life trauma that typically drives an addiction."
Gabe Deem, the founder of Reboot Nation, often describes this group of consumers as "opportunity addicts". This is when someone develops porn addiction because they enjoy the content—then they develop emotional, social or mental health issues as a result of excessive porn use.
In addition to these expert accounts, to date, every neurological study published offers support for the addiction model (no studies falsify the porn addiction model). Our "go-to" papers and educational videos are listed here. Apparently in reliance on such research, in 2019 the World Health organization adopted a diagnosis that can be used by those struggling with compulsive porn use. It's called "Compulsive sexual behaviour disorder" (CSBD). More on that in a moment.
Tactical move: create doubt and confusion
Aside from doing all they can to deny the impacts of porn on the brain, porn-harms science-deniers typically create contention and unnecessary confusion around the supposed difference between "compulsive sexual behaviour" and "addiction". Yet those suffering from compulsive behaviour are less concerned with labels and more concerned with getting help. The new CSBD diagnosis will make that help possible.
Interestingly, most of the research on which the world health experts relied upon when adopting "Compulsive sexual behaviour disorder" was done on internet pornography users. In adopting the new diagnosis, it's clear that the experts were concerned about the potential impact of today's pornography on users' health.
So where does one get clarity?
When a person is struggling with the amount of porn they use or the impacts it's having on their relationships, a starting point would be to assess their behaviours using the ICD-11 diagnostic tool that defines compulsive sexual behaviour disorder. According to the American Psychological Association (APA), the International Classification of Diseases (ICD) is produced by the World Health Organisation, a global health agency with a constitutional public health mission, while the DSM (Diagnostic and Statistical Manual of Mental Disorders) is produced by a single national professional association (in the U.S.). The DSM uses the ICD coding and was last updated in 2013. It's already out of date in the fast-moving world of pornography research. The new ICD diagnosis is being used by academics, and others will incorporate it over time.
The ICD-11 states that compulsive sexual behaviour disorder is characterized by a persistent pattern of failure to control intense, repetitive sexual impulses or urges resulting in repetitive sexual behaviour. Symptoms may include repetitive sexual activities becoming a central focus of the person's life to the point of neglecting health and personal care or other interests, activities and responsibilities; numerous unsuccessful efforts to significantly reduce repetitive sexual behaviour; and continued repetitive sexual behaviour despite adverse consequences or deriving little or no satisfaction from it. The pattern of failure to control intense, sexual impulses or urges and resulting repetitive sexual behaviour is manifested over an extended period of time (e.g., 6 months or more), and causes marked distress or significant impairment in personal, family, social, educational, occupational, or other important areas of functioning. Distress that is entirely related to moral judgments and disapproval about sexual impulses, urges, or behaviours is not sufficient to meet this requirement.
While addiction is not mentioned in the definition and guidelines for diagnosing someone with compulsive sexual behaviour (CSB) disorder, a person with addictive sexual behaviours, including compulsive pornography use, would meet the above test.
Where can porn addicts find more information ... and hope?
There are several things someone can do when they recognise their consumption is out of control or bordering on porn addiction.
Take a look at the ICD-11 definition of Compulsive Sexual Behaviour Disorder and reflect on whether this could apply. Avoid the urge to try and self-diagnose, but this could be a useful yard-stick to start finding answers.
Seek professional help from someone well-informed about behavioural addictions.
Read about other people's experiences. Great places to start are on forums such as NoFap and Reboot Nation – millions of people struggle with porn addiction, and online communities can help give hope and encouragement for those who previously felt they were alone. Who better to learn from than those who have recovered or are facing the same challenges!
Get educated. There's a whole list of informative sites on the Youth Wellbeing Project website, including links to research.
Use filters, apps and recovery resources. Here's a list to get started.
Expand your understanding of why pornography is a public health crisis. Every click creates demand for exploitation, and porn sites are complicit in allowing child sexual exploitation material, revenge porn, rape and other non-consensual materials on their sites.
If you have kids, it's likely that you don't want them to struggle with porn addiction so it's important to reframe your understanding and pass on helpful information for their healthy sexual development. Visit the Culture Reframed Parents Program to help you build young people's resilience and resistance. Also, Porn Resilient Kids equips families for tricky conversations through educational resources and blogs, children's books, resource links and a closed Facebook group.
If you are still confused, know this: The porn industry is well-aware that their content is addictive and they've been known to brag about it. If you are one of the millions who have been caught up in their targeted efforts to create life-long consumers, you are not alone and you can recover. I'm told that it is harder to kick than cigarettes, but the health benefits are overwhelmingly worth it.
Next time someone says porn addiction doesn't exist, ask more questions, look behind the smokescreen, and form your own conclusion. The weight of the evidence does not favour the deniers. I'll just keep educating and encouraging people to raise kids with skills for critical porn analysis—until a new generation of scientists can all see through the industry's smokescreen and add to our understanding of porn addiction. Currently, it's a condition that impacts millions because of the unregulated industry that drives it.
Definitely saving this. Next time someone says porn addiction doesn't exist, point them to the research, ICD-11, user's stories, clinicians comments AND Pornhub's admission. Not looking good for the porn-harms science-deniers. https://t.co/X3FDGnwEiO
— Liz Walker (@LizWpresents) June 5, 2020
If you or loved ones are struggling with pornography's impacts, you need to know that you are not alone. Click through for educational information, resources and links to online support services. And if you are looking for a presenter, professional development, curriculum to deliver in schools, or support for families, visit Youth Wellbeing Project and send us an email.
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