Comparative life cycle assessment of ceramic brick, concrete brick and cast-in-place reinforced concrete exterior walls

Accepted Manuscript Comparative life cycle assessment of ceramic brick, concrete brick and cast-in-place reinforced concrete exterior walls Danielle Maia De Souza, Mia Lafontaine, François Charron-Doucet, Benoit Chappert, Karine Kicak, Fernanda Duarte, Luis Lima PII:

S0959-6526(16)30957-X

DOI:

10.1016/j.jclepro.2016.07.069

Reference:

JCLP 7641

To appear in:

Journal of Cleaner Production

Received Date: 29 March 2016 Revised Date:

11 July 2016

Accepted Date: 12 July 2016

Please cite this article as: De Souza DM, Lafontaine M, Charron-Doucet F, Chappert B, Kicak K, Duarte F, Lima L, Comparative life cycle assessment of ceramic brick, concrete brick and castin-place reinforced concrete exterior walls, Journal of Cleaner Production (2016), doi: 10.1016/ j.jclepro.2016.07.069. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Word count: 10,446 Title: COMPARATIVE LIFE CYCLE ASSESSMENT OF CERAMIC BRICK, CONCRETE

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BRICK AND CAST-IN-PLACE REINFORCED CONCRETE EXTERIOR WALLS

Author names and affiliations:

Danielle MAIA DE SOUZAa,b**, Mia LAFONTAINEc, François CHARRON-DOUCETc**, Benoit CHAPPERTd, Karine KICAKc, Fernanda DUARTEe, Luis LIMAe**

University of Alberta, Department of Agricultural, Life & Environmental Sciences, Edmonton

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a

(AB) T6G 2P5, Canada

Swedish University of Agricultural Sciences, Department of Energy and Technology, PO Box

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7032, SE-75007, Uppsala, Sweden c

Groupe AGÉCO (formely Quantis Canada), 395, Ave Laurier O., Montreal (QC) H2V 2K3,

Canada d

Quantis Switzerland, EPFL Innovation Park, Bat. D, Lausanne, 1015, Switzerland

e

Associação Nacional da Indústria Cerâmica Vermelha (ANICER), Rua Santa Luzia, 651 12º

**

Corresponding

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Andar – Centro, Rio de Janeiro (RJ), 20030-041, Brazil

authors:

Danielle

MAIA

DE

SOUZA.

Email

address:

[email protected] (D.Maia de Souza); François CHARRON-DOUCET. Email address:

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[email protected]

(F.

Charron-Doucet);

Luis

LIMA.

Email

address:

[email protected] (L.Lima).

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NOTE: All the authors have equally contributed to this work.

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ABSTRACT

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The construction sector has a meaningful contribution to the global scarcity of natural resources, as well as with impacts on the natural environment. Most life cycle assessments have focused on impacts associated with the energy efficiency of buildings, in particular during the operational phase. However, the construction phase of buildings accounts for a significant share of a building’s embodied energy and is responsible for impacts related to resource depletion. With the aim to contribute to more all-embracing assessments in the construction sector, this study aims to compare three different wall types commonly used in Brazil, according to their environmental performances: ceramic brick, concrete brick and cast-in-place reinforced concrete exterior walls. The results were analyzed with the software SimaPro 7.3 and with the life cycle impact assessment method IMPACT 2002+ (version Q2.2). Ceramic brick walls have less impact than the concrete brick and the cast-in-place reinforced concrete exterior walls on three different endpoint indicators (Climate Change, Resource Depletion and Water Withdrawal). The results were not significant regarding impacts on Human Health and Ecosystem Quality. Different sensitivity analyses were carried out in order to test the final results, as well as uncertainty analysis, related to the variability of inventory data and the characterization of the life cycle inventory results into midpoints and/or endpoints.

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KEYWORDS: Life Cycle Assessment; Ceramic bricks; Concrete blocks; Brazil; SimaPro; IMPACT 2002+ .

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1. INTRODUCTION

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The construction sector contributes significantly to the global consumption of raw materials and energy (Cabeza et al., 2014; Koroneos and Dompros, 2007). Life Cycle Assessment (LCA) is increasingly being employed to evaluate the environmental performance of buildings, building elements, and construction materials (Buyle et al., 2013; Russel-Smith et al. 2015). The focus of current LCA studies has mainly been on the analysis of energy efficiency of buildings and greenhouse gas (GHG) emissions from buildings’ life cycles (Ng and Mithraratne, 2014; Zabalza Bribián et al., 2011; Zhang et al., 2013). Indeed, the primary energy consumption in buildings is around 40% of the total energy consumption in most European countries (Persson and Grönkvist, 2015). However, more all-embracing assessments have been increasingly employed to improve sustainable design and compare different construction materials and elements (Souza et al., 2015) and building technologies (Bianchini and Hewage, 2012). This is because although the operational phase of buildings is very energy intensive (Allouhi et al. 2015; Perez-Lombard et al. 2008), contributing to around 90% of the total life cycle energy use (Dimoudi and Tompa, 2008), the construction phase is responsible for a significant share of the total embodied energy of the building (Asif et al., 2007). This is particularly true for low-energy buildings (Blengini and Di Carlo, 2010; Monteiro and Freire, 2012), in which the total energy may consist of a high contribution from the production and maintenance of building components (Dimoudi and Tompa, 2008). Moreover, the construction sector is one of the main consumers of raw-materials, leading to resource depletion (Sieffert et al., 2014; Zimmermann et al., 2005).

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Numerous LCA studies have been carried out in different building components: roofing (Bianchini and Hewage, 2012; Kosareo and Ries, 2007; Souza et al., 2015) and flooring systems (Nebel et al., 2006; Nicoletti et al., 2002), doors (Cobut et al. 2015a,b) windows and glazing systems (Citherlet et al., 2000; Werner and Richter, 2007), and walls (Castell et al., 2013; Ingrao et al., 2016; Koroneos and Dompros, 2007). However, among these, few studies have been carried out in developing countries, where the construction sector is generally at an increasing growing rate (Han et al., 2015). For instance, an increase (4.5%) in sales of the construction sector has been recently observed in Brazil (ABRAMAT, 2015). Regardless of the overall decreasing trend in overall sales of the construction sector, the ceramics sector experienced a growth of 18.7% in 2015 (ABRAMAT, 2015), showing its economic importance in the Brazilian construction market. The aim of this study is to identify and understand the environmental impacts over the cradle-tograve life cycle of an average ceramic brick exterior wall in Brazil and compare its environmental performance with the one of concrete brick exterior walls and of cast-in-place reinforced concrete exterior walls in Brazil. With that aim, the goal and scope of this study is defined, including the identification of the common functional unity and the specification of the system boundaries for each of the three studies wall systems. Second, the study’s assumptions

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are presented along with the sensitivity analyses that were carried out in order to test the final results. Third, the results of the four analyses carried out are presented: (i) the comparative LCA of the wall types, (ii) the contribution analysis of the life cycle stages of each wall type to five indicators, (iii) the sensitivity analysis carried out, and (iv) the uncertainty analyses. Finally, recommendations for a better environmental performance of ceramic bricks are drawn. 2. MATERIALS AND METHODS

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2.1 Goal and scope of study The goal of the study is to assess and compare the environmental life cycle impacts of three types of wall construction elements, from the extraction of raw-materials to their end of life: (i) ceramic bricks, (ii) concrete bricks, and (iii) cast-in-place reinforced concrete walls. Each product is representative of the average building wall construction practices in Brazil and their life spans are specified in the ABNT NBR 15.575 standard (ABNT, 2013).

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The functional unit for this study is defined as the “construction and maintenance of one square meter - one meter (length) per one meter (height) - of exterior wall, above ground, with a life span of 40 years in Brazil”. The wall construction should fulfill two main functions: (i) to support the structural integrity of a building and (ii) to protect a building interior from external weather conditions (e.g. rain, wind, snow), while helping maintaining thermal insulation. The characteristics of the wall (including the wall thickness) are defined to ensure that structural resistance to compression, thermal insulation, soundproofing and esthetics are equivalent (Table 1). Although ceramic walls have better insulation than the concrete walls, it is assumed that all three types of wall meet their standardized minimum criteria on thermal insulation.

Characteristics

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Table 1. Main characteristics of the wall types studied, and the associated reference flows. It is assumed that the three wall types (ceramic brick wall, concrete brick wall and cast-in-place reinforced concrete wall) have a life span of 40 years.

7.5 0.14 13 bricksa,b (97.5kg of ceramic, 15kg of mortar for bindingc, and 0.4 kg of steel rods) Mortar Coating (total 62.5 kg of dry coating quantity/m2 for of wall) 5.75 L of water Support Structure Forms None (kg/m2) Life span (years) 40 a Considering a 4% loss b Brick dimensions: 14 cm x 19 cm x 39 cm

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Brick weight (kg) Wall thickness (m) Wall construction (quantity of material for 1m2 of frontage)

Ceramic bricks

Cast-in-place reinforced concrete 12 0.14 0.12 13 bricksa,b,d (156 kg of 300 kg of concrete concrete, 15kg of mortar 9.48 kg of steel rods for bindingc, and 0.4 kg 22.8 L of water of steel rods) 0.24 L of additives 62.5 kg of dry coating 0 5.75 L of water None 0.063 kg of aluminum Concrete bricks

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Mortar composition rate for binding: 1:0.6:5 (cement:lime:sand) Brick composition: 20% dry weight (Portland cement) and 80% dry weight (sand). This data was provided by ANICER, (ANICER, personal communication, July 2011) d

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The system boundaries of the life cycles are presented in Figure 1 (Ceramic brick wall), Figure 2 (Concrete brick wall) and Figure 3 (Cast-in-place reinforced concrete wall). The transportation scenarios for all three systems are shown on Table 2.

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Ceramic bricks are made from clay with the addition of water. Clay extraction, the preparation of clay dough and the shaping of bricks is performed with retro-excavators, wheel loaders and bulldozers, as explained in Souza et al. (2015). Argillite (hardened clay, rendering a higher quality product), obtained by excavation through blasting, can also be used in replacement of clay. The clay dough is prepared using a loading shovel and mechanical mixing. The bricks are then shaped using molds and dried. During the drying stage, the moisture content of the clay dough is reduced from 25% to 3% of its mass (SEBRAE, 2008). The firing stage takes place in furnaces with temperatures around 950oC (Monteiro and Vieira, 2004), with posterior heat recovery, and wood chips are supplied as a waste product from the wood furniture industry. The material losses (1.5%) are either reprocessed and incorporated into the dough (up to 5%) or used for building tennis court terrains. Bricks are then laid on pallets, wrapped in plastic foils and transported by lorry to storage and to end-customers. Mortar, used for ceramic and concrete bricks, is made from a mix of cement (15%), lime (9%) and sand (76%). The mix of pre-mixed dry mortar (92%) and water (8%) is used to manually bind the building blocks. At the end-oflife, it is assumed that each of the studied wall types (ceramic, concrete, cast-in-place reinforced wall) is destroyed and the waste is sent to a landfill.

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Concrete bricks consist of a mixture of sand, cement, crushed stone and water. Sand is extracted from river sand pits or may as well be obtained from crushing rocks, while limestone is extracted from open quarries (using explosives). Clay is obtained in the same way as for ceramic bricks. During manufacturing, limestone and clay (9:1) are mixed in the raw mill. The raw meal produced undergoes grinding (up to an average particle size of 0.050 mm) and the resulting flour is homogenized in large vertical silos through pneumatic and gravity processes. This flour is preheated in the oven, calcined up to 1450oC (SNIC, 2011) in a rotary kiln, and cooled to 80oC. The commercial cement mix is obtained by the mixture of clinker, gypsum and additives. The bricks are then produced with a blend of cement (20%), sand (70%) and water (10%), shaped and left to air dry, before they are palletized. The bricks and the mortar are laid manually. Cast-in-place reinforced concrete is made of sand, cement and water, poured around steel rods, and some additives. The additives consist of melamine-formaldehyde resin (29% formaldehyde and 71% melamine). Sand and cement are obtained in the same way as for concrete bricks and the production of the cement mix is as for the concrete bricks production, as well as the blend of 5

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cement, sand and water. However, cast-in-place reinforced concrete contains semi-finished products of steel production, which are processed by scarfing, grinding, heating, de-scaling and rolling. Hot rolling causes the coarse grain structure to recrystallize into a much finer grain structure, giving greater toughness, shock resistance and tensile strength. The forms used are made of aluminum (most widely used) or galvanized iron or steel. The reinforcing armor or rods are made of a mix of primary and secondary steel. The steel mix in Brazil is assumed to be representative of the world average: 70% steel from a basic oxygen furnace (BOF), 30% from an electric arc furnace (EAF).The impurities resulting from this process (e.g. sulfur, phosphorus, and excess carbon) are removed from the raw iron. Generic data on primary aluminum production for the forms is obtained from the Ecoinvent v.2.2 database (SCLCI, 2010) and includes cast aluminum ingot production (with its plant), transport of materials to the plant and the disposal of wastes. During the construction phase, the cast-in-place reinforced concrete the wet concrete is poured on the steel rods in a formwork. The cement mixer truck is left running and uses a pump to pour the concrete. As a result, fuel consumption and emissions of the truck associated with this operation (pouring concrete) are considered and calculated with the NONROAD model, developed by US EPA. This model calculates emission inventories for nonroad equipment, considering different fuels, geographic location and time period. Mortar is not used in the cast-in-place system.

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Table 2. Transportation scenarios for all three studied systems. For all three systems, the transportation of raw-materials used to produce mortar is assumed to occur by truck (53-dry box trailer truck). The payload was specified by ANICER for most transportation stages. When there was no availability of data, an average payload of 17.56 t was used in the study. Total roundtrip distances Ceramic Concrete Cast-in-place brick brick concrete wall Transportation from the clay quarry to the ceramic 54 km brick manufacturing plants Transportation from the site of extraction of sand, 150 km 150 km 150 km limestone and clay to the cement and premixed mortar production plants Transportation of pre-mixed mortar (in paper bags 25 km 25 km 25 km and palletized) to end customer Transportation from the cement plants to the 300 km 300 km premixed mortar production and concrete brick manufacturing plants Transportation from the steel rods production plants 800 km to the end customer Transportation from the customer to landfill 50 km 50 km 50 km

2.2 Life Cycle Inventory

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Primary life cycle inventory (LCI) data was provided mainly by the Brazilian Nacional Ceramic Industry Association (ANICER) and used to generate generic datasets representative of the average values for the Brazilian ceramic and concrete industries. Missing, incomplete or nonaccessible data were completed by secondary data, such as Ecoinvent v.2.2 database, public available datasets, literature review and expert judgment (Table A.1, Table A.2 and Table A.3 in Appendix A). The use of the European data from Ecoinvent v.2.2 to represent Brazilian processes can introduce some bias in certain areas. However, it is believed that the consistency and accuracy of this database make it a preferable option for representing Brazilian conditions compared to other available data for most processes. The Brazilian electricity grid mix was used (Table A.4 in Appendix A) for all primary processes, as in Souza et al. (2015). The main source of electricity is from Hydropower (83.70%), followed by natural gas (4.83%) and biomass from bagasse (3.96%).

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2.3 Assumptions Several general assumptions were made throughout this study.

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Concrete manufacturing process. There was a general lack of information for emissions from concrete manufacturing in Brazil, in particular, for fuel combustion in the clinkerization step (process required to produce the cement for the mortar). Ecoinvent data on emissions from the concrete manufacturing was therefore used in the analysis, adapted to Brazilian data on road transportation (e.g. distances), sand and cement proportions, and brick size: GHG emission ratio of 0.838t CO2-eq per ton of cement.

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Wall life span. The life span of any of the walls analyzed in this study is considered to be 40years, during which it is assumed that the mortar coating on the outside face of the wall does not need to be repointed. This value meets the minimum requirement set by the Brazilian national standard NBR 15575 (ABNT, 2013). It is assumed that after 40 years, the wall is destroyed and sent to landfill. The cast-in-place reinforced concrete wall does not require the application of the mortar to meet the 40-year life span, although it helps ensuring optimal performance. Thermal insulation and soundproofing performance. It is assumed that in all three scenarios, the material used granted little thermal insulation and soundproofing (Lemieux and Totten, 2009). However, as the minimal criteria on thermal insulation and soundproofing performance stated on the legislation were met, no sensitivity analysis was performed on this aspect. As ceramic brick walls have better insulation than concrete walls, the first were modeled in a conservative scenario, not considering this advantage over its concrete wall equivalents. Resistance to compression. It is assumed that the minimal criteria on resistance to compression, according to legislation and regulation in buildings and construction in Brazil have been met;

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therefore no sensitivity analysis was performed on this aspect for which little variability is possible.

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Cement production. This study used cement production emission data from Ecoinvent v.2.2, with average clinkerization fuel mix adapted to Brazilian conditions (CCAP, 2009), as shown in Table A.5, in Appendix A. However, no detailed flue gas emissions data were available to update the output of the process and emission data from Ecoinvent was retained: emission data from 1998, published by the USEPA (Kellenberger et al., 2007). Therefore, a sensitivity analysis was carried out in order to evaluate the sensitivity of the CO2 emissions to different fuel mixes for Canada (Nyboer and Rudd, 2011) and for Brazil (CCAP, 2009).

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Use stage (wall assembling and maintenance). During the wall construction, losses of bricks (ceramic and concrete) are assumed to be of 4% for both materials, as information provided by ANICER. The same percentage is assumed for losses of mortar used for binding and coating and construction materials. For the cast-in-place reinforced concrete wall scenario, this study assumed 4% losses of wet concrete in the concrete mixer. End-of-life. In this study, for any of the wall types, it is assumed that all the losses occurring during the life cycle are landfilled, unless otherwise specified. The same assumption is made for all the construction materials at their end-of-life.

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2.4 Sensitivity analysis A series of sensitivity analyses were carried out to evaluate the influence of generic data assumptions and methodological choices on the results of this study. First, the life span (including the mortar) of ceramic walls was tested in comparison to concrete brick wall and castin-place reinforced concrete wall. Second, the use of different raw-materials, as argillite, used for the production of ceramic tiles and artificial sand for the production of concrete was also tested. The use of different types of support structure forms, for the cast-in-place reinforced concrete wall, was analyzed, as well as the application of mortar on this same wall. Due to the existing uncertainty in data on transportation, this study evaluated if a change in the distribution distances of finished products to storage and the use of packaging for ceramic bricks would alter the results. The emissions from cement production, the loss rates of the bricks and the mortar, the origin and amount of the wood chips in the firing step for the ceramic brick wall were as well investigated. Finally, a different allocation method and another life cycle impact assessment (LCIA) method (ReCiPe) were employed to check if these choices would influence the results. 2.5 Uncertainty analysis Two types of uncertainty analysis were carried out in this study. First, an analysis to verify the uncertainty related to the variability for both primary and secondary inventory data, assessed with a Monte-Carlo simulation. Finally, an analysis was carried out to verify the characterization

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of the LCI results into midpoint indicators and the characterization of the midpoints into endpoint indicators (Humbert et al., 2009).

3. RESULTS AND DISCUSSION

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2.6 Life Cycle Impact Assessment This life cycle assessment study was carried out with the software SimaPro 7.3 (PreSustainability, 2013), using the LCIA method IMPACT 2002+, VQ2.2 (Humbert et al., 2012). Results were expressed in 17 midpoints (Table 3). Midpoints are regrouped in three endpoint indicators (also called damage indicators): Human Health, Ecosystem Quality and Resources Depletion). In addition to endpoint indicators, Climate Change and Water Withdrawal indicators are also discussed in greater depth in this article (Table 4). The release of chemicals into the outdoor environment and the human exposure to that environment were considered for the assessment of impacts on Human Health, while the direct exposure through indoor air or dust was excluded from the analysis. No weighting of midpoint and endpoint indicators was performed nor was normalization of data carried out, following ISO 14040 (ISO, 2006) recommendations for comparative assertions.

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In this section the results of the different analyses are presented: (i) the comparative LCA of wall types, (ii) the contribution analysis of the life cycle stages to each indicator, (iii) the sensitivity analysis, and (iv) the uncertainty analysis.

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3.1 Comparative LCA of wall types In this study the different walls were compared in the baseline scenarios and expressed the results of the midpoint (Table 3) and endpoint (Table 4) indicators in percentage. Equations [1] and [2] were employed to calculate the impact difference (%) when comparing ceramic bricks to concrete bricks and cast-in-place reinforced concrete wall, respectively. The scores refer to the results of the LCA analysis.

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% = (Scoreconcrete brick – Scoreceramic brick)/Scoreceramic brick % = (Scorecast-in-placeconcrete– Scoreceramic brick)/Scoreceramic brick

[1] [2]

The results show that, in general, the ceramic brick wall causes lower impacts at midpoint than the concrete brick and the cast-in-place concrete walls. However, uncertainties linked to the characterization models do not allow discriminating between these three types of bricks for the carcinogens, non-carcinogens, aquatic and terrestrial ecotoxicity indicators. Table 3. Midpoint impact relative differences (in %), when comparing ceramic bricks to concrete bricks and cast-in-place reinforced concrete wall (1 m2), using IMPACT 2002+, VQ2.2 (refer to equations [1]

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and [2] for the calculation procedure). A positive score means that ceramic performs better than the alternative option. Midpoint indicators

Ceramic bricks versus Ceramic bricks versus concrete bricks cast-in-place concrete wall 46%1) 560%1) 1) 60% 340%1) 1) 10% 72% 82% 104% 74% 125% 44% 84% 69%1) 293%1) 58%1) 217%1) 32% 43% 19% 33% 44% 92% 77% 257% 74% 167% 51% 1245% 100% 195% 61% 392% 32% 8%

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Carcinogens Non-carcinogens Respiratory inorganics Ionizing radiation Ozone layer depletion Respiratory organics Aquatic ecotoxicity Terrestrial ecotoxicity Terrestrial acidification/nitrification Land occupation Aquatic acidification Aquatic eutrophication Non-renewable energy Mineral extraction Global warming Turbined water Water withdrawal

The difference does not allow taking conclusions, due to uncertainty in the LCIA model

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Regarding endpoint modelling, the ceramic brick wall has a lower impact on Climate Change and Resource Depletion than concrete equivalents (Figure 4). GHG emissions over the life cycle of 1 m2 of a ceramic brick wall (32.1 kg CO2-eq/m2) are roughly half those of 1 m2 of a concrete brick wall and a third those of a cast-in-place reinforced concrete wall. The Resource Depletion score of a ceramic brick wall, which mainly refers to consumption of non-renewable energy, is also around half of the score of a concrete brick wall and around 37% of the score of a cast-inplace reinforced concrete wall.

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Table 4. Relative differences of scores to selected indicators (in %), when comparing ceramic bricks to concrete bricks and cast-in-place reinforced concrete wall (1m2), using IMPACT 2002+, VQ2.2 (refer to equations [1] and [2] for the calculation procedure). A positive score means that ceramic performs better than the alternative option. Selected indicators Climate Change Human Health Ecosystem Quality Resource Depletion Water Withdrawal 1)

Ceramic bricks versus concrete bricks 100% 14%1) 51%1) 74% 32%

Ceramic bricks versus cast-inplace concrete wall 195% 102%1) 181%1) 170% 8%

The difference in the results does not allow conclusions, according to model uncertainty.

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The results for the ‘Water Withdrawal’ indicator show that the life cycle of the ceramic brick wall produces lower impacts compared to the concrete brick and cast-in-place reinforced concrete wall scenarios (Table B.1, in Appendix B). Due to uncertainties related to the characterization of damages on Human Health and Ecosystem Quality, no conclusions could be taken on the less impacting wall type life cycle. However, the results still provide valuable information to better understand the environmental impacts caused by the life cycle of each product. For all three wall types, the main damages to Ecosystem Quality are attributable to the Aquatic and Terrestrial Ecotoxicity midpoint indicators (Table B.2, in Appendix B). Damages to Human Health are mainly caused by Respiratory Inorganics midpoint indicator, as a result of the emission of fine particles and nitrogen oxides emissions (Table B.2, in Appendix B).

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3.2 Contribution Analysis

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The concrete brick manufacturing process has a great impact on Climate Change and Resource Depletion (Figure 5 and Table B.1, in Appendix B), as a result of the use of fossil fuels for energy production. Conversely, the ceramic manufacturing process makes use of residual wood chips as an energy source, which increases considerably the impacts of fine particles emitted during combustion on Human Health. Still, the concrete brick wall scenario appears to have a larger impact on Ecosystem Quality and Human Health, although the difference between the results is not significant to take concrete conclusions. As the Water Withdrawal indicator is an inventory indicator, it does not have an uncertainty related to the LCIA. Hence, the only uncertainty that can be considered is the one calculated with the Monte Carlo. For the ceramic brick wall versus concrete brick wall comparison, Monte Carlo results indicate a robust conclusion for this indicator (Table D.1. in Appendix D). However, in the comparison of ceramic versus cast-in-place reinforced concrete wall, no robust conclusions can be taken (Table D.2. in Appendix D.

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Ceramic brick wall. The impacts associated with each life cycle stage of the ceramic brick wall to the five indicators were calculated (Table 5). Absolute results can be found in Table B.3, in Appendix B. Table 5. Results for the contribution analysis (in %) of each life cycle stage of ceramic brick wall to he five selected indicators.. Life cycle stage

Extraction Transportation from extraction Dough preparation Forming operation Drying Firing

Climate Change

Human Health 3 5 7 1 0 1

6 5 14 1 0 19

Ecosystem Resource Water Quality Depletion Withdrawal 2 4 0 7 6 1 5 9 3 1 1 0 0 0 0 9 1 0

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13 35 4 22 9

4 13 4 23 11

5 19 7 32 13

7 24 4 28 16

69 13 2 6 4

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Binding Coating Steel rods Distribution End-of-life TOTAL

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Coating constitutes the main source of impact to Climate Change (35% of total CO2-eq emissions, i.e. 11 kg CO2-eq/m2), resulting from GHG emissions from the clinkerization process, required to produce the cement for the mortar. Total transportation also constitutes another important source of impact, mainly due to exhaust CO2 emissions from fuel combustion (26% of total CO2-eq emissions, i.e. 8.4kg CO2-eq/m2). The percentages, however, do not include biogenic carbon dioxide released by the combustion of wood chips (12.7 kg CO2-eq/m2) during the firing stage. The replacement of wood chips by fossil fuels would have a significant negative impact on this indicator. The largest contributor to damages to Human Health is the total transportation (28% of total contribution to DALY, i.e. 8.7E-06 DALY/m2), due to the emission of nitrogen oxides (NOx) during fuel combustion. The firing state is the second contributor (18% of total contribution to DALY, i.e. 5.8E-06 DALY/m2), as a result of fine particle emissions (PM2.5) from wood combustion, which are associated with respiratory problems.

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Damages to Ecosystem Quality are mainly associated with metals emitted during tire abrasion, during total transportation (total impact of 2.7 PDF.m2.yr/m2, i.e. 39% of total impact on Ecosystem Quality). However, ecotoxicity models for metals released into soils and water bodies have a low reliability (Rosenbaum et al., 2008, Henderson et al., 2011), hence there is a high uncertainty over the Ecosystem Quality indicator. The coating step is the second largest contributor to this indicator (~19% of the total contribution to Ecosystem Quality), mainly resulting from the construction of crude oil wells (required to extract crude oil for the diesel used in the production process). More specifically, aluminum (Al) and zinc (Zn) from the drilling wastes end up in the soil when the wastes from the well construction are spread onto farming land. The end-of-life of the ceramic bricks also contributes largely (13%, i.e. 8.9E-01 PDF.m2.yr/m2) to the overall damage to Ecosystem Quality. The distribution (i.e. diesel for transport) and the coating steps (i.e. use of fossil fuels for the energy-intensive process of cement production) contribute respectively with 28% (1.1E+02 MJ primary/m2) and 24% (9.5E+01 MJ primary/m2) to the total damages to Resource Depletion (Table B.3, in Appendix B). However, the fuel used for heat production in the firing stage is not accounted for in this indicator because of its renewable nature. In this study, the extraction of sand, clay and limestone was considered to have no impact on Resource Depletion, as the

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reserves of these minerals are abundant enough, i.e., the surplus extraction energy is close to zero.

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Finally, the water used for the production of the lime included in the mortar (binding) accounts for ca. 70% (i.e. 8.3E-01 m3/m2) of the total contribution to the Water Withdrawal indicator (Table 5).

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Concrete Brick Wall. The stage of concrete brick production is the main responsible for the impacts to four indicators (Table 6). For the Water Withdrawal indicator, the binding stage contributes with an important amount of water used for the lime production (46%, data extracted from Ecoinvent), followed by the concrete brick production (26%) with water withdrawals during sand extraction and during clinker production. Absolute results are available in Table B.4, in Appendix B.

Concrete brick production Binding Coating Steel rods Distribution End-of-life TOTAL

Climate Change

Human Health 55 6 17 2 13 6

Ecosystem Quality

100

Resource Depletion

Water Withdrawal

45 3 11 4 24 13

43 3 12 5 26 11

47 5 14 2 20 12

26 53 10 1 6 4

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Life cycle stage

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Table 6. Results for the contribution analysis (in %) of each life cycle stage of concrete brick wall to the score of the five selected indicators..

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The main contributors to Climate Change are the concrete brick production – mainly due to cement production (55% of total contribution to kg CO2-eq, i.e. 3.5E+01 kg CO2-eq/m2) - and coating stages (17% of total contribution to Climate Change, i.e. 1.1E+01 kg CO2-eq/m2), mainly due to the GHG emissions from the clinkerization process. Typically, around 45% of CO2 emissions released during the brick production are a product of the chemical reaction occurring during calcination. This step requires a great deal of heat, generated from fossil fuels. Transportation for distribution is another important source of greenhouse gases (13% of total CO2-eq emissions, i.e. 8.4E+00 kg CO2-eq/m2), contributing with exhaust CO2 emissions due to fuel combustion. In a similar way, the main contributor to damages to Human Health is the stage of concrete brick production, as a result of nitrogen oxides (NOx) emissions during fossil fuel combustion in the clinkerization step. Distribution (24% of total DALY/m2, i.e. 8.6E-06 DALY/m2) and end-of-life (13% of total DALY i.e. 4.5E-06/m2) contribute as well with NOx emitted during transport truck fuel combustion.

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Ecosystem Quality is mostly damaged during concrete brick production, as a result of Al and Zn release from the drilling wastes during the construction of oil wells and spread onto farming land. The contribution of this life cycle stage corresponds to 43% (1.1E+01 PDF.m2.yr/m2) of the total impacts to this indicator. Distribution is the second most important contributor (26% of total damage to this indicator, i.e. 2.7E+00 PDF.m2.yr/m2), due to the metals released in tire abrasion. However, as ecotoxicity models for metals released into soils and water bodies have a low reliability, there is a high uncertainty over the results for the Ecosystem Quality indicator.

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Resource Depletion is mainly damaged by the use of fossil fuels (petroleum coke for Portland cement production and clinker production and fuel for truck consumption) during concrete brick production (47% of total damage, i.e. 3.3E+02 MJ primary/m2) and distribution transport (20% of total damage, i.e. 1.4E+02 MJ primary/m2).

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Cast-in-place Reinforced Concrete Wall. The concrete production stage represents 52% (i.e. 4.9E+01 kg CO2-eq/m2) of the total score of Climate Change (Table 7), due to GHG emissions during the clinkerization process. The production of the steel rods constitutes the second source of damage (30%, i.e. 2.8E+01 kg CO2-eq/m2), as a result of GHG emissions associated with coal burning from power plants for the energy-intensive process of steel production. The absolute contribution can be found in Table B.5, in Appendix B.

TOTAL

Ecosystem Quality

Resource Depletion

Water Withdrawal

52 0 30 1 3 3 6 5

26 0 49 1 3 5 7 9

22 0 60 2 2 5 2 8

37 0 35 1 5 4 8 10

49 2 34 2 3 2 2 7

100

100

100

100

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Concrete production Water Steel rods Aluminum form Additive Distribution Wall building End-of-life

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Table 7. Results for the contribution analysis (in %) of each life cycle stage of cast-in-place reinforced concrete wall to the impacts caused to the five selected indicators.

Along the life cycle of cast-in-place reinforced concrete wall, steel rods production is the main contributor (49% of total contributions, i.e. 3.1E-05 DALY/m2) to damages to Human Health (Table 7). These damages are associated with the emissions of fine particles (PM2.5) during steel rods production and cause respiratory problems. The emissions of nitrogen oxides (NOx) during

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fossil fuel combustion in the clinkerization step (concrete production) also represent a significant contribution (26%, i.e. 1.6E-05 DALY/m2) to this indicator.

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The steel rod production is also the largest contributor (60% of total contributions, i.e. 1.2E-01 PDF.m2.yr/m2) to damages to Ecosystem Quality (Table 7). These damages result from metal emissions in ferrochromium and ferronickel productions (e.g. airborne aluminum during blasting operations, as well as chrome and nickel emissions during production process). The second largest contributor is the concrete production (22% of total contributions, i.e. 4.3E+00 PDF.m2.yr/m2), responsible for emissions from drilling waste for petroleum coke production. However, ecotoxicity models for metals released into soils and water bodies have a low reliability, causing high uncertainty over the Ecosystem Quality indicator. The high energy demand for steel rod production also assigns this process the largest contributions to damages to Resource Depletion, followed by the use of fossil fuels for energy-intensive process of cement production during Portland cement production. Important quantities of water are withdrawn during concrete production (clinker production) and extraction of gravel and sand. Steel rod production is responsible for 34% (i.e. 4.4.E-01 m3 water/m2) of the total contributions to Water Withdrawal, due to the use of cooling water at the coal power plant for the energy-intensive process of steel production.

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3.3 Sensitivity analyses In this study, the following sensitivity analyses were carried out (Appendix C):

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Life span of wall alternatives. Baseline scenarios were compared with longer (50 years) and shorter (30 years) life span walls, in order to grasp the influence of this parameter (life span) in the final results of the study (Fig. C.1 and Fig. C.2 in Appendix C). The sensitivity analysis demonstrated that the outcome of the comparison between ceramic and concrete alternatives would be retained (differences between compared options were too small to be considered significant).

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Use of argillite in clay extraction. The use of this new raw-material had no impact on the results, except for Ecosystem Quality, as also verified by Souza et al. (2015). The increased impact on Ecosystem Quality narrowed the gap between the scenario comparisons, making it more difficult to discriminate between the scenarios. Use of artificial sand in concrete production. The use of artificial sand (and extra crushing step) did not have an impact on the final results. Transport distances for bricks distribution. The influence of different scenarios for transportation distances on the final results were investigated: increased ceramic brick distribution distances (200 km, 500 km and 1000 km) and reduced concrete and reinforced

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concrete distribution distances (50 km) . The results show that the impacts are always lower for the ceramic brick wall than for the concrete brick and cast-in-place reinforced concrete walls for the Climate Change indicator (Fig. C.3 in Appendix C). The results for Human Health, Ecosystem Quality, Resources and Water Withdrawal were also lower for the ceramic brick, as long as the distribution distances did not exceeded, respectively, 200 km, 500 km, 500 km and 500 km. Therefore, this analysis supports the beneficial aspect of a ceramic brick wall in comparison to the concrete alternatives.

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Use of packaging for ceramic bricks. Due to the increasing use of packaging for ceramic bricks, this scenario was tested. The results of the comparison between ceramic and concrete bricks obtained showed a marginal difference, confirming that the packaging did not have a relevant impact on the overall results.

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Emissions from cement production. A sensitivity analysis around different emission scenarios was carried out, using data provided by the Cement Association of Canada (CAC, 2011), in contrast to the original US emission data (Ecoinvent database), used in the baseline scenario. The value of 0.649 t CO2/t of cement (Brazil specific CO2 intensity) was used, as opposed to 0.75 t of CO2/t of cement for the baseline scenario. Only a variation of 10% for damages to Human Health was observed (Fig. C.4 in Appendix C).

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Loss rates of the brick and the mortar. Higher loss rates (10% and 25%) for the ceramic bricks were investigated and compared the results to the concrete bricks and cast-in-place reinforced concrete wall scenarios (Fig. C.5 in Appendix C). The analysis demonstrated that higher loss rates can have a relatively high impact on the overall results. Yet, when considering a loss rate of 10% for the ceramic brick wall, the impacts related to each indicator are still lower than that for the concrete brick wall and the reinforced concrete wall. One exception were the results for the Water Withdrawal indicator, which were slightly higher for the ceramic brick than for the castin-place reinforced concrete wall.

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Types of support structure forms. Aluminum forms are widely used in Brazil, as a support structure for the construction of cast-in-place reinforced concrete walls, although other metals can also be employed for this purpose (e.g. reinforcing steel and stainless steel forms). Stainless steel forms had the highest impact on all categories, in particular Human Health and Ecosystem Quality, as a result of the chromium emissions from steel production (Fig. C.6 in Appendix C). Cast-in-place reinforced concrete with aluminum forms (base scenario) has the lowest overall impact. Yet, the baseline scenario using aluminum support structure forms still presents a worse environmental performance than the ceramic brick wall scenario. Amount and origin of wood chips. The ceramic bricks firing step is processed with furnaces burning mostly wood chips (or other organic waste material), supplied as a waste product from

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the sawmill industry. This data was obtained directly from ANICER. These wood chips are mainly made of industrial wood, but a certain part may come from residual wood (directly taken from forest).The wood chips were modeled using a generic process, detailed in the Ecoinvent database, where the impact of wood production is allocated amongst the different direct forest products (i.e., industrial wood, round-wood and residual wood). An economical allocation is used, while a correction based on volume is added to account for the mass and energy, with regard to the CO2 uptake and resource consumption from nature (SCLCI, 2010). A first sensitivity analysis was conducted to study the influence of the allocation of the impact of the direct forest products to the use of wood chips. The allocation factor itself is not a parameter that can be easily modified. However, since a variability on the allocation factor would simply have a direct effect on the amount of wood chips used, the parameter that was tested in this analysis was the amount of wood chips required (for example, an increase in the allocation factor would result in an increase in the amount of wood chips required for the firing). The results showed that the amount of wood chips used had little influence on the results (Fig. C.7 in Appendix C). The amount of wood chips used for the firing stage would need to be twice higher than the amount used in the baseline scenario to cause a change in the baseline scenarios’ results.

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A second sensitivity analysis assessed the results obtained for the ceramic brick wall scenario, using wood chips originated from the forest, as opposed to industrial wood (baseline scenario). The results of this analysis indicated that the conclusions remained unchanged: the ceramic brick wall still outperforms the concrete brick wall (Fig. C.8 in Appendix C).

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Use of a different allocation method. The cut-off allocation method was used in this study, in order to assess the impacts associated with the life cycle of residual wastes used in the cement manufacturing fuel mix. The sensitivity to this allocation method was tested in Souza et al. (2015), by testing the influence of system boundaries expansion. The waste recovery was assigned to the use of tires, i.e. as residual waste (11%) in the fuel mix, for energy recovery, replacing the production of energy based on coal. The whole impact of functionally equivalent fuels was considered in this study. Emissions from combustion stage were assumed to remain the same, following studies conducted by the Portland Cement Association (PCA, 2008). The results showed that the choice of allocation method has trivial impact on the overall results, as consequence of the small contribution to the total fuel mix. Use of a different LCIA method: ReCiPe. The use of ReCiPe (Hierarchist) method (Goedkoop et al., 2009) led to similar conclusions for most midpoint categories (Table 8), except for Land Occupation, for which the ceramic brick wall had a worse performance in comparison to the concrete brick (-3%) and cast-in-place reinforced concrete walls (-36%). In a similar manner, the ceramic brick wall presented worse results (-7%) for Water Withdrawal, when compared to the cast-in-place reinforced concrete

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wall. It is notable that the method of characterization used in this study (IMPACT 2002+) only takes into account impacts resulting from land occupation and not those resulting from land transformation (Allacker et al., 2014). In the IMPACT 2002+ analysis, the ceramic brick wall presented better results associated with impacts from natural land transformation (Table 8). The land use transformation for the wood chips is defined as a transformation from forest extensive to forest intensive and road embankment.

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The mineral extraction midpoint indicator as calculated by IMPACT2002+ considers the impact on resource depletion from minerals extracted by calculating the additional energy required to extract five times the cumulative extracted amount since the beginning of extraction (Humbert et al., 2012; Jolliet et al., 2003). In the case of sand, clay and limestone, the reserves of these minerals are abundant enough that the surplus extraction energy is close to zero. For that reason, the extraction of these minerals has no impact on the Mineral Extraction midpoint indicator. Similarly, in ReCiPe only Metal and Fossil Depletion midpoint categories are included in the Resources indicator. Therefore the impact on resources due to extraction of sand, clay and limestone is not captured by both LCIA methods.

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For Water Withdrawal, the difference between the results lays in different inventory data input. IMPACT 2002+ considers water use (in m3 of water needed, whether it is evaporated, consumed or released again downstream) without turbined water (i.e., water flowing through hydropower stations). It considers drinking water, irrigation water and water for and in industrialized processes (including cooling water), freshwater and sea water as well. Instead, the Water Depletion midpoint indicator in ReCiPe does not include cooling water and water for processes. For this reason, the total volume of water accounted for in both methods is different. The comparison of both methods is shown on Table 8 (midpoint impact differences, in %).

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Table 8. Comparative Midpoint LCA results for ceramic bricks versus concrete bricks and cast-in-place reinforced concrete wall (1 m2) (IMPACT 2002+ and ReCiPe). Ceramic bricks vs. concrete bricks IMPACT 2002+

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Impact category

ReCiPe

46% (carcinogens)

Human Toxicity

Respiratory inorganics Ionizing radiation Ozone layer depletion Respiratory organics

61% (noncarcinogens)

29%

Ceramic bricks vs. cast-in-place concrete wall IMPACT ReCiPe 2002+ 560% (carcinogens) 306% 340% (noncarcinogens)

10%

27%

72%

126%

82%

82%

104%

105%

74%

74%

125%

126%

44%

--

84%

--

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69%

48%

293%

636%

58%

52%

217%

157%

32%

47%

43%

104%

Aquatic acidification Aquatic eutrophication Non-renewable energy Mineral extraction Global warming Turbined water Water withdrawal

33%

-36% (agricultural land occupation) 141% (urban land occupation) 575% (natural land transformation)

44%

--

92%

--

77%

31% (marine) 66% (freshwater)

257%

88% (marine) 417% (freshwater)

74%

74%

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Land occupation

-3% (agricultural land occupation) 57% (urban land occupation) 254% (natural land transformation)

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19%

167%

170%

51% 100% 61% 32%

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Aquatic Ecotoxicity Terrestrial Ecotoxicity Terrestrial acid/nutrification

66% 100% -27%

1245% 195% 392% 8%

1166% 194% --7%

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3.4. Monte-Carlo uncertainty analysis The variability of most elementary flows from the Ecoinvent database, used in this study is represented by a lognormal distribution around the central value specified (and used for the deterministic calculations), characterized by its standard deviation. This variability is however not statistically determined using real measurement, but estimated by applying a pedigree matrix describing the data quality by its origin, its collection method and its geographical, temporal and technological representativeness (Weidema and Wesnæs, 1996). Some data have also been associated with a uniform statistical distribution, bounded by minimum and maximum values.

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Similarly, the variability of most of the data collected (ANICER) was represented by a lognormal distribution whose standard deviation was estimated using the same matrix pedigree, or with a uniform statistical distribution, bounded by minimum and maximum values. In the comparison between the ceramic brick wall versus the concrete brick and the cast-in-place reinforced concrete walls, 71.1% of the data model is represented by a distribution on variability. The remaining 28.9% of the data have no uncertainty and therefore was considered as fixed data since they come from direct calculation. However a distribution was applied to most of the primary data (71.1%). The simulation performs the subtraction of two compared systems, where the results indicate the probability that one option generates more damage than the other.

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For the comparison with the concrete brick wall, the probability that “the construction and maintenance of 1m2 of wall using ceramic bricks” generates more impacts than “the construction and maintenance of 1m2 of wall using concrete bricks” are 0% for Climate Change, Ecosystem Quality and Resource Depletion; 10,9% for Human Health; and 5,4% for Water Withdrawal (Table D.1, in Appendix D). This statistical analysis does not take into account uncertainty related to the impact assessment model, which previously showed that in no way comparative results on Human Health and Ecosystem Quality could be considered significant. Therefore, the inventory data uncertainty analysis confirms the robustness of the results presented for the other three indicators.

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For the second comparison, the probability that “the construction and maintenance of 1m2 of wall using ceramic bricks” generates more impacts than “the construction and maintenance of 1m2 of wall using cast-in-place reinforced concrete” are: 0% for Climate Change and Resource Depletion, 0,2% for Human Health, 0,4% for Ecosystem Quality and 50,7% for Water Withdrawal indicator (Table D.2, Appendix D). The inventory data uncertainty analysis confirms the robustness of the results presented for all of the indicators, with the exception of Water Withdrawal, where the probability of the occurrence of an inversion A ≥ B (Water Withdrawal cast-in-place concrete wall ≥ Water Withdrawal ceramic brick wall) is of 50.7%. This uncertainty analysis thus indicates that it is not possible to differentiate between these two scenarios as to which requires the least amount of water to be withdrawn throughout its life cycle. As for Water Withdrawal, the Monte-Carlo assessment presented in the section indicates a high uncertainty associated with the results for the amount of water withdrawn, so conclusions cannot be made based on this indicator.

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The results for the Monte Carlo uncertainty assessment for midpoint categories can be found in Table D.3, in Appendix D (ceramic brick wall versus concrete brick wall) and Table D.4, in Appendix D (ceramic brick wall versus cast-in-place reinforced concrete wall).

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4. DISCUSSION AND RECOMMENDATIONS The main differences between the environmental impacts the ceramic and the concrete brick walls resulted from different transformation processes and use of different natural resources. The concrete brick production requires limestone and clay to be calcined into cement at very high temperatures reaching 1450°C, producing an intermediate material that will set into the final product using only sand and water, air-dried at room temperature. In addition, the higher temperature of the clinkerization process requires a more intensive combustion, using mostly fossil fuels. As for the production of ceramic bricks, oven temperature is lower, (~950°C), while the entire brick must be baked, for a longer period of time. Since cement constitutes 20% of concrete bricks (ANICER, 2011), the energy required per m² of wall is much higher for walls made of concrete. As a result of the use of fossil fuels for energy production, the concrete

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manufacturing process has a great impact on Climate Change and Resource Depletion. Conversely, the ceramic manufacturing process uses residual wood chips as an energy source instead of fossil fuels, thereby significantly reducing impact on Climate Change and Resources depletion during manufacturing while increasing impact on Human Health from fine particles emitted during combustion. However, in a general way, a ceramic brick wall has lower impacts than a concrete brick wall for all categories. Concrete bricks walls also appear to have a larger impact on Ecosystem Quality and Human Health; however the difference is not significant when compared to the ceramic brick wall scenario.

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The difference in impact between the ceramic bricks and cast-in-place reinforced concrete is also due to the use of different natural resources with varying degrees of transformation to set into a solid and durable construction material. However, the degree of difference is mostly driven by the impact of the steel rod production for the cast-in-place concrete on Human Health and Ecosystem Quality, which is due to emissions of fine particles during the production process of the raw materials required to make steel. Steel production requires a great amount of energy for its production, and since the quantity used is about 24 times higher than for the ceramic brick wall, its impact on Climate Change and Resources is accordingly also greater. In a general way, the ceramic brick wall had lower impacts than the cast-in-place reinforced concrete wall for all categories. However for Human Health and Ecosystem Quality, the difference was not significant.

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The sensitivity analyses carried out, as well as the uncertainty assessment performed using Monte-Carlo iterations, have shown that the conclusions of this LCA are robust except for the Water Withdrawal indicator. For this reason, it is not possible to assert that a ceramic brick wall withdraws less water than a concrete brick wall or a cast-in-place reinforced concrete wall over its life cycle. In general, the studied ceramic brick wall had lower impacts than the concrete brick and cast-in-place reinforced concrete walls for all categories. However, for Human Health and Ecosystem Quality the difference could not be considered significant, for an ascertained conclusion. The results of this study may lead to important actions to reduce the life cycle environmental impacts associated with the ceramic brick production. First, since the emission of fine particles released during the combustion of wood chips is the main contributor to Human Health impacts, a focus on filtration of fines could be beneficial. Second, due to the importance of the transportation steps in all impact categories, alternative measures could be investigated, such as shipment by boat or train, the use of biofuels, etc. Environmental relevance of these alternatives should always be validated with a life cycle approach specific to the context. For instance, the results of this study and conclusions are context specific, i.e. associated with the data and assumptions applied in the analyses.

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However, this study has some limitations. First, several parameters are assumed to remain constant across the Brazilian geography evaluated. This means accuracy may not be fully guaranteed. This applies namely to manufacturing process, transportation distances, fuel mixes for firing and clinkerization, and building structure required to support the walls. Second, some LCI data implemented describe European operations (Ecoinvent v.2.2), implying that this study may not be fully representative of Brazilian practices (and thus impacts). However, a database of equivalent quality, transparency, and robustness is not yet available for Brazil or other geographies (beyond Europe) from which the Brazilian building industry may source its materials. For instance, the processes used in cement and concrete manufacturing were modeled based on Ecoinvent data. Only transportation distances and the grid mix and fuel mix were adapted for the Brazilian context. Moreover, emissions from fuel combustion were not adapted to the Brazilian context. Third, the Ecoinvent modules that were used to describe cement and concrete productions are a typical technology that has not evolved much over the last decade, and are more than likely still a good representation of the specific technology that is used to produce the given cement and concrete products assessed in this study.

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ACKNOWLEDGEMENTS This study was funded by ANICER, who is thankful to Groupe AGÉCO (formely Quantis Canada) and Quantis International partnership, as well as to the external collaborator Danielle Maia de Souza, for the important support to understand the work carried out and the preparation of the LCA study. We are thankful to the following external experts, who carried out the critical review of the data quality and verified information credibility: Marisa Vieira, PRé Consultants b.v.; Carlos Augusto Xavier Santos, School SENAI Mario Amato; Rosa Maria Crescencio, SENAI School Orlando Lavieri Ferraiuolo; and Cassia Ugaya, ACV Brasil.

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Figure 1. System boundaries for the ceramic brick wall life cycle, comprising from the extraction of raw materials up to the end of life. Figure 2. System boundaries for the concrete brick wall life cycle, comprising from the extraction of raw materials up to the end of life. Figure 3. System boundaries for the cast-in-place reinforced concrete wall life cycle, comprising from the extraction of raw materials up to the end of life.

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Figure 4. Normalized results for ceramic bricks versus concrete bricks and cast-in-place reinforced concrete wall, using IMPACT 2002+. Figure 5. Comparative analysis of environmental life cycle stages for each of the analyzed building elements/materials (ceramic brick, concrete brick and cast-in-place concrete) and their contribution to each indicator (Climate change (CC), Human health (HH), Ecosystem Quality (EQ), Resources (RS), and Water withdrawal (WW)). The analysis was done using IMPACT 2002+, VQ2.2.

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Highlights * We compared the environmental impacts of three wall types commonly built in Brazil

* We run different sensitivity analyses to test the final results

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* Differences in impacts mainly result from the use of distinct natural resources and processes

* The concrete manufacturing process has a great impact on Climate Change and Resource Depletion

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* The environmental performance of ceramic bricks is improved by filtering fine particulate matter