Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective

Waste Management xxx (2015) xxx–xxx

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Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective Valérie Cappuyns ⇑, Valentine Deweirt, Sandra Rousseau KU Leuven, Centre for Economics and Corporate Sustainability (CEDON), Warmoesberg 26, 1000 Brussels, Belgium

a r t i c l e

i n f o

Article history: Received 15 July 2014 Accepted 25 December 2014 Available online xxxx Keywords: Contamination Risk perception Valorisation Willingness to pay

a b s t r a c t A possible solution for the oversupply of dredged sediments is their use as a raw material in brick production. Despite the fact that several examples (e.g., Agostini et al., 2007; Hamer and Karius, 2002; Xu et al., 2014) show that this application is feasible, some economic, technical and social limitations interfere with the development of a market of dredged materials in brick production in Flanders. While we describe the main characteristics of the supply side, we focus on the limitations and barriers from the demand side in the present study. Based on a consumers survey we analyze consumers’ risk perceptions and attitudes towards bricks produced from dredged sediments. Consumers in Flanders are rather suspicious with respect to bricks produced from dredged sediments and their risk perception is mainly determined by the possibility of a bad bargain (brick of inferior quality) and the connotation with chemical contamination. The willingness to pay for bricks made from dredged sediments is mainly influenced by the age of the respondents, as well environmental awareness, and the respondents’ belief in their ability to influence environmental problems. Sensitization and information of customers seems to be of primary importance to make dredged-sediment-derived bricks a successful product. Ó 2015 Elsevier Ltd. All rights reserved.

1. Introduction Dredged sediments consist of soil material originating from deepening, broadening and maintaining of public waterways and from the establishment of new shipping infrastructure. In Flanders (Belgium), approximately 12,000 kton of dredged sediments has to find a destination every year (Nielsen et al., 2010). A possible application is the use of dredged sediments as a raw material in brick production. Despite the fact that several examples (e.g., Agostini et al., 2007; Hamer and Karius, 2002; Xu et al., 2014) show that this application is feasible, some economical, technical and social limitations interfere with the actual use of dredged materials in brick production in Flanders. With respect to technical issues, the problem of dewatering of sediments as a very energy-demanding and costly process seems to have been partly solved. In the AMORAS project (Dockx and De Broe, 2008) mechanical dewatering using chamber filter presses is used as an economically viable alternative for lagooning. It also enables to properly control the dewatering process. This

⇑ Corresponding author. Tel.: +32 2 608 1453. E-mail address: [email protected] (V. Cappuyns).

mechanical dewatering process yields an end product of superior quality, and it opens up new applications for re-use, such as the partial replacement of clay in bricks (Dockx and De Broe, 2008). At the moment, it is not completely clear why the beneficial use of dredged sediments as a secondary resource in brick manufacturing is not applied on a commercial scale. Based on a review of relevant literature, the feasibility of brick production from dredged sediments as well as the potential environmental impacts associated with bricks will first be discussed. Besides technical and environmental aspects concerning the (re)use of dredged sediments, the legal framework in Flanders will briefly be addressed. These represent essential components of the supply side of the market. When the feasibility of brick production from dredged sediments is addressed, consumers’ acceptance and willingness to pay for bricks produced from dredged sediments are important factors to gain insight into the demand side. Until now, information on this topic is still scarce. The present study will focus on the consumer demand for bricks produced from dredged sediments, investigating the most relevant aspects that influence the potential market success of this kind of product from a consumers point of view. Although the present study was performed in Flanders, the outcome of this study is interesting for any region or organization that has to deal with dredged sediments.

http://dx.doi.org/10.1016/j.wasman.2014.12.025 0956-053X/Ó 2015 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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2. Overview of the supply side: legal, technical, environmental and economic aspects First we give a brief overview of the relevant legislation in Flanders. Next we discuss the technical and economic feasibility of using dredged sediments in brick production as well as its environmental impact. 2.1. Legislation with regard to the reuse of dredged sediments Legislation with regard to the removal and treatment of dredged sediments is an important issue for the dredging industry. Although there is no specific legislation with regard to dredged sediments on the European level, several other European regulations are partly applicable on the dredging industry: the European Water Framework Directive 2000/60/EC, the Waste Framework Directive 2008/98/EC, the Habitats Directive 92/43/EEC, and the Groundwater Directive 2006/118/EC. In Belgium, where environmental legislation is a regional competence, the act on environmental permits (VLAREM), the soil remediation act (VLAREBO) and the materials management act (VLAREMA) are relevant to handling and using dredged sediments in Flanders. The new act on materials management (VLAREMA), that came into force in Flanders in 2012, considers dredged sediments as a secondary resource. Thus dredged sediments can be used as a resource for building materials as long as they comply with certain criteria. These criteria consist of threshold values with respect to the maximum permissible content of contaminants in the sediments and on the leachability of heavy metals from these sediments (assessed with a diffusion test) (Table S1, Supplementary data). Three possible reuse scenarios are envisaged, namely reuse as building material (e.g., highway embankments, fills, subgrades and subbases, bricks, lightweight aggregates, etc.), reuse as soils and reuse as sealing layer for a landfills. So, if the sediment complies with the criteria under the Flemish legal framework for reuse of waste materials, it can be re-used as construction material. 2.2. Technically possible applications and environmental impact Pretreatments of sediments before beneficial use include dewatering of sediments (and treatment of the water effluents), but also more thorough treatments such as chemical stabilization of contaminants (e.g., addition of compost or lime; Wang et al., 2011) or vitrification (McLaughlin et al., 1999). Once dewatered, dredged sediments can find several useful applications. They can be applied as a mixing material for concrete (Oh et al., 2011), as a resource to produce light weight aggregates (Wei et al., 2008), pavement base materials (Dubois et al., 2009) or as material in road layers (Siham et al., 2008; Wang et al., 2011; Achour et al., 2014). In The Netherlands mounds made of (contaminated) dredged material offer protection against flooding (Bernardini and van Duijvenbode, 2005). Because clay and sand are non-renewable primary resources, their substitution by secondary resources such as sewage sludge (e.g., Cusidó et al., 2012), metallurgical slags (e.g., Shih et al., 2004; Pioro and Pioro, 2004) and sediments has been envisaged. Several examples are found in literature of sediments and alluvial deposits as the major raw material input for the production of building bricks and tiles (e.g., Bhatnagar and Goel, 2002; van der Meulen et al., 2009). In the United States (Mezencevova et al., 2012) and Malaysia (Salim et al., 2012), the feasibility of producing bricks in which clay was partly replaced by dredged sediments, was demonstrated on laboratory scale. In Northern France (Agostini et al., 2007) and Germany (Hamer and Karius, 2002) a full-scale industrial experiment was conducted at a brick factory in which contaminated sediment was used for brick production.

In the French study, the sediment was first stabilized by the NovosolÒ process. The NovosolÒ process (Agostini et al., 2007) consists of a chemical inertization of heavy metals followed by thermal elimination of organic pollutants, whereafter the treated sediment can then be used as a partial replacement of quartz sand (Samara et al., 2009). The substitution of quartz sand by treated sediment results in a significant increase in brick compressive strength and firing shrinkage, and in a decrease in porosity and water absorption (Table S2, Supplementary material). Moreover, the crushed bricks comply with all environmental standards so as to be accepted as non-hazardous material (Samara et al., 2009). In the German case study, manufacturing of bricks with harbour sediments from Bremen (Table S2, Supplementary material) could be optimized (with regard to physical and mechanical properties), and the resulting bricks showed no environmental impact (total contaminant content, leaching of contaminants) restricting their application. In a Chinese study (Xu et al., 2014) urban river sediments were suitable as a primary raw material in the production of high-insulation bricks, heavy metals concentrations leaching from the bricks remaining far below the thresholds. Besides leaching of contaminants, other aspects such as the use of primary resources and energy significantly contribute to the environmental impact of bricks (Koroneos and Dompros, 2007). For example, by using energy efficient tunnel kilns with heat recovery (Bribián et al., 2011). The environmental impact of brick production can also be significantly reduced by promoting the use of the best techniques available and eco-innovation in production plants, substituting the use of non-renewable natural resources for materials or waste generated in other (production) processes, preferably available locally (Bribián et al., 2011). In this respect, dredged sediments could be beneficially used to partially replace clay as a raw materials in bricks, as far as the criteria with regard to the quality of the bricks and environmental safety can be met. This substitution of virgin resources is also an economic benefit of using dredged sediments, but unfortunately its value in monetary terms is low. The market (supply side) for dredged sediments and the technical and economic possibilities for use of dredged sediments as a secondary resource in Flanders have been analyzed in detail in two reports of the Flemish Institute for Technology (Nielsen et al., 2003, 2010). The most realistic options for secondary use of dredged sediments are the use of sandy material as a filler or as building material in Flanders. From an environmental and technical point of view, dredged sediments are not always a full-fledged alternative for primary resources. Because of the excess of other secondary resources, for example from soil excavations, dredged sediments would have to be distributed at negative prices to be economically interesting. The difference between bricks made from dredged sediments and traditional bricks in terms of profitability lies in the fact that the price of clay in Flanders is in the range 3–4 euro/ton (Nielsen et al., 2010). Because drying of sediments is expensive, dredged sediments - that could partly replace clay – are actually more expensive than natural clay. A long as there are sufficient clay resources, using dredged sediments to partly replace clay in bricks will not be economically interesting. The monetary benefits that can be realized by the current valorisation options (use of sand fraction as a filler or in building applications) cannot even offset the cost of landfilling the fraction that is not used. The economic advantage of using dredged sediments (in any application) should be higher than the cost of landfilling (±20 euro/ton) (Nielsen et al., 2010). Despite the fact that numerous studies show that bricks made from dredged sediments meet all quality and safety criteria, consumers’ belief should also be considered. Especially their beliefs concerning possible contaminants in dredged sediments and bricks, as well as quality and esthetical aspects of this kind of bricks, are crucial elements when commercial applications are envisaged.

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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3. The demand side: market potential and consumers’ attitude Environmental behavior of consumers is typically influenced by a number of different factors. We distinguish two main categories: individual and contextual factors (Tanner and Kast, 2003; Kollmuss and Agyeman, 2002). Individual factors include (1) specific attitudes, (2) perceived risks, (3) knowledge, and (4) personal norms. Contextual factors, on the other hand, reflect the social, economic, or physical environment within which people act. Firstly, a consumer survey by Mainieri et al. (1997) supports the suggestion that specific consumer beliefs predict environmentally friendly consumer behavior more accurately than does general environmental concern. It is often observed that general environmental awareness does not necessarily lead to a specific environment-friendly behavior (e.g., Young et al., 2010). Evidence of this attitude-behavior gap is given by Hughner et al. (2007), who showed that, despite the generally favorable attitudes that consumers hold for organic food (between 46% and 67% of the population), actual purchase behavior forms only 4–10% for different product ranges. Some consumers are only green when it comes to certain products (e.g., Peattie, 1992, 2001). For instance, some consumers only buy green when they buy things for their children (Peattie, 1992). Moreover, consumers often regard environmentally friendly products as expensive and technically inferior (e.g., Bhate, 2002; Peattie, 2001). Further, green consumers tend to be green only when they trust the manufacturer and/or the label. According to Peattie (2001), 90% of UK consumers had a skeptical attitude towards green promotional campaigns. Secondly, consumer behavior is affected by the risk that consumers associate with particular products. While a higher perceived risk generally leads to a lower willingness to purchase a product or service, this relationship is not necessarily a linear one. For example, this is illustrated by the role of impulsiveness in buying unhealthy food products (Talukdar and Lindsey, 2013). While this perceived risk can be based on the physical risk of using a product, there is typically a discrepancy between consumer and scientific risk evaluations. Consumers’ risk perceptions are influenced by public and social acceptability of a product. For instance, Siegrist et al. (2005) mentions that social trust (i.e., trust in specific entities) strongly influences the risk perception of individuals concerning particular technologies. Specifically, individuals who put higher trust in authorities perceived fewer risks than individuals not having that trust. For example, in the late 1990s a number of food safety crises, such as the dioxin crisis, considerably decreased consumers’ image of meat safety in Belgium (Verbeke, 2001). While perceptions have shifted, the impacts in terms of behavior or purchase were very limited (Verbeke, 2001). Trust is thought to be especially important in the absence of knowledge (Siegrist et al., 2005). Besides public factors, the personality of an individual also influences risk perceptions (Sparrevik et al., 2010). A person can be a risk taker by nature, or on the contrary be a very careful person, always showing utmost caution. This can affect his risk perception and resulting behavior. Personal characteristics of self-sufficiency and independence are positively correlated with risky behavior, whereas inflexibility shows a negative correlation with risky behavior. Based on the negative correlation between risky behavior and risk perception, it was concluded that people with a more risk-loving nature generally show a lower risk perception (Mitchell, 1999). Besides personal characteristics, product characteristics also play a role in risk perception. Loyalty towards a specific brand reduces the perceived risk, and the risk perception is also influenced by the symbolic value of a product, the probability of a bad bargain and/or the value of satisfaction of a product (Mitchell, 1999). In general, complex products are characterized by a higher value and imply a higher involvement of the consumer.

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A higher risk is attributed to these more complex products compared to more ordinary products with a lower value. In the present study, we deal with a complex product (bricks made from dredged sediments), for which risk perception will most likely be a significant factor to explain why people would buy this kind of bricks or not. Thirdly, environmental knowledge has been found to be positively related to environmental attitudes (Bamberg, 2003), but the literature reports contradictory findings on the question of how ecological knowledge is related to environmental behavior. For example, Ajzen et al. (2011, p.106) found that ‘the accuracy of factual information (i.e., knowledge) regarding the environment was largely irrelevant for determining environmentally friendly intentions and behavior’. One option to bring information to consumers is through the use of labeling schemes. However, some consumers might have a thorough knowledge of and preference towards some labels but not towards others, e.g., they intentionally buy paper products with an FSC label, but they do not recognize organic labels on food products. Some consumers are even green without knowing it. For instance, Pedersen and Neergaard (2006) concluded that more than half of the consumers buy labeled textiles without recognizing the labels. Green consumers might also be manipulated into buying products that are not green, because they are unaware of the actual content of a label and its verification. For instance, Cason and Gangadharan (2002) found that one-third of all green advertising claims are vague and/or misleading. This phenomenon of firms or products that pretend to be greener than they really are, is referred to as ‘greenwashing’ (Laufer, 2003). Fourthly, numerous studies have revealed that a personal norm—a feeling of moral obligation—is a powerful motivator of environmental behavior (e.g., Biel and Thøgersen, 2007; Göckeritz et al., 2010). Moreover, Roberts (1996) suggests that consumers must be convinced that their behavior has an impact on the environment or will be effective in fighting environmental degradation in order to motivate behavioral changes. Finally, contextual factors reflecting social, economic, or physical environment are also very important. Socio-demographic factors such as available income, gender and age influence proenvironmental behavior. The legal context also matters as it delineates consumers’ and producers’ options. In addition, product characteristics affect consumer choices. Among these product characteristics, the actual risk associated with a product is especially relevant in the current context. Previous research indicates that ‘green’ or ‘sustainable’ products are generally more expensive, making financial risk also relevant, whereas for non-sustainable products, physical risks prevail (Mitchell, 1999). In some instances, these contextual factors can keep pro-environmental attitudes from being expressed in action. For instance, even if a person is motivated to buy green products, he or she cannot buy such goods if they are not offered for sale in an accessible location (Tanner and Kast, 2003). 4. Methods In the present study, the limitations and barriers to develop a market for bricks made from dredged sediments were analyzed from the consumers’ point of view, based on interviews and on a survey held in 2011 in Flanders (Belgium). The survey dealt with consumers’ willingness to pay for bricks produced from traditional raw materials and from (contaminated) sediments. The aim of the present survey was to investigate whether there exists a market for bricks produced from dredged sediments and to identify the motivations and barriers of consumers to buy this kind of product. In what follows, bricks made from dredged sediments will be indicated with the term ‘‘sedibricks’’. One of the aims of

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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V. Cappuyns et al. / Waste Management xxx (2015) xxx–xxx

the survey was to identify groups of consumers who are not interested in sedibricks, who would be interested when sedibricks are sold at a discount, or those who are interested in sedibricks and might even be willing to pay a price premium. Therefore, the barriers perceived by consumers (quality, price, etc.) and the factors determining a consumer’s risk perception (Mitchell, 1999) were taken into account. The survey consisted of 50 questions, including questions on demographic aspects (age, gender, occupation, education, etc.), personality characteristics (flexibility, self-confidence, etc.), market segmentation (based on the DEFRA model), technical knowledge (quality of bricks, environmental effects, etc.), risk perception and behavior, and willingness to pay for sedibricks. In the survey the DEFRA 4E model (DEFRA, 2008) was used to map the characteristics of the potential market for this kind of bricks. To map consumer behavior, we collected information regarding the different factors that influence consumer behavior as discussed in Section 3. Looking first at the individual factors, we have used several scale items to measure environmental attitudes. We also measured relevant personal attitudes relating to risk, confidence and flexibility. In addition, several questions relating to perceived risks were presented to the respondents and we asked about the respondent’s attitude towards living in a house built with sedibricks. Further, we measure respondents’ general environmental knowledge by asking them about the percentage of surface waters with contaminated bottoms sediments in Flanders as well as their general level of trust in different sources of information. Moreover, we included several scale items reflecting personal norms relating to environmental beliefs into the survey. Finally, we also look at the contextual factors. The relevant legislation and the product characteristics were discussed in Section 2 and are taken as given. The survey was constructed with the online survey software Qualtrics, and the link to the survey was distributed by e-mail. The survey was also distributed on paper in order to include people who do not have regular internet access. In total, approximately 770 people received the survey, of which 439 people replied to the survey (response rate of 57%). The high response rate is due to the biased and self-selecting nature of our sampling method. Since we used a non-stochastic sampling method, our sample is not representative for the whole population. Still the analysis provides interesting insights into the market potential of sedibricks by explicitly accounting for the different characteristics of the respondents. The data obtained from the survey were processed with Stata software. Firstly, a factor analysis was used to analyze respondents’ environmental beliefs and attitudes. Secondly, a logit model was used to estimate the probability that a respondent would buy sedibricks if they had the same price and quality characteristics as conventional bricks. We estimate the following logistic function (Greene, 2003) with Y the choice of the respondent (1 = buy sedibrick; 0 = buy conventional brick), X a set of explanatory variables and b the estimated coefficient): 0

ProbðY ¼ 1jXÞ ¼

eb X 0 1 þ eb X

ð1Þ

Thirdly, a multinomial logit model was used to study the willingness to buy and pay for sedibricks since we analyze a discrete choice set (Greene, 2003). Respondents had to indicated whether they were willing to buy the product and pay a premium (1), buy the product at a competitive price (2), buy the product at a discount (3), were not willing to buy the product (4) or were of another opinion (5). The respondent’s choice Yi for a particular option j e {1, 2, 3, 4, 5} can be explained using a set of explanatory variables Xi with i an index representing respondent i. The model for the respondents’ choice is then (with bi representing the estimated coefficients):

0

ebj Xi ProbðY i ¼ jÞ ¼ P5 b0 X k i k¼1 e

ð2Þ

5. Results and discussion In this section we first present the general characteristics of our respondents and discuss their risk perception. We also perform a factor analysis in order to identify the constructs underlying respondents environmental attitudes. Next we analyze the factors that influence demand for sedibricks and finally we discuss the potential to promote sedibricks as a green product. 5.1. General characteristics, environmental awareness and risk perception With respect to the general socio-demographic characteristics, all respondents have the Belgian nationality. The majority of the respondents had a higher education or university degree (Table 1). The data with respect to characteristics related to the respondents’ personality indicate that 56.61% of the respondents make the majority of the decisions in their household, while 34.34% asks advice from other persons in over half of the decisions they make (any decisions). Most of the respondents do not have a very risky nature and consider themselves as moderately confident and rather flexible (Fig. 1). The characteristics related to environmental beliefs and attitudes were addressed by using a list of 13 statements (with a Likert scale) to determine the attitude of respondents regarding the urgency to solve environmental problems. A principal factor analysis was performed to identify the number of factors (constructs) that underlie the observed variables and therefore opportunities for data aggregation. Based on the Kaiser–Meyer–Olkin measure, the results for two statements (if KMO > 0.65) were removed. The factor analysis showed that underlying the remaining 11 statements three factors could be distinguished. The rotated factor loadings are provided in Table 2. The three factors can be translated in three types of environmental beliefs or attitudes: factor 1 expresses the respondent’s environmental awareness, factor 2 can be translated into the usefulness of taking action to decrease the impact on the environment, and factor 3 expresses the difficulty of taking action (Table 2). In the survey, the characteristics related to building and bricks were also addressed. Respondents could select at most three aspects they considered important when choosing bricks. The respondents considered technical aspects and price as the important characteristics of building bricks, whereas less than 25% indicated ‘‘safety’’ and ‘‘environmental impact’’ as important aspects (Fig. 2). In addition, 16.2% of the respondents had specific building or renovation plans at the moment of participating in the survey. This high number of building or renovation plans is unsurprising for the Belgian market. Between 2003 and 2013, on average 26,798 residential buildings were newly built and 27,926 residential buildings were (profoundly) renovated each year in Belgium (FOD economie, s.d.). Based on a population of approximately 11 million individuals, this implies that each year some 0.5% of the population is involved in building or renovating. Minor renovations are not included in the official statistics since no building permit is required. When asked which risks they associated with bricks made from dredged sediments, the majority of the respondents (60%) indicated that they had insufficient information to answer the question (Table 3). Some 18% felt that there were risks associated with the bricks, while 22% thought there were no risks at all associated with the bricks.

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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V. Cappuyns et al. / Waste Management xxx (2015) xxx–xxx Table 1 General socio-demographic characteristics of the respondents. Percentage female respondents

47.62%

Education – highest degree obtained No degree Primary school Secondary school (general orientation) Secondary school (technical orientation) Secondary school (professional orientation) Additional vocational training Higher, non-university degree University degree

0% 4.76% 12.78% 16.29% 5.26% 4.76% 30.83% 25.31%

Pre-tax income (incl. wages, pensions, benefits, etc.) Less than 1500 euro per month Between 1501 and 2500 euro per month Between 2501 and 3500 euro per month Between 3501 and 4500 euro per month More than 4501 euro per month

24.31% 31.33% 31.08% 9.27% 4.01%

Current job status Factory worker Office worker Civil servant Self-employed, CEO, profession Job seeking House man/wife Pensioner Student

15.29% 41.10% 6.52% 5.26% 0.75% 2.26% 11.78% 17.04%

Respondents with children younger than 12 or with frequent visiting children younger than 12

45.11%

Age of respondents Older than 80 Between 71 and 80 Between 61 and 70 Between 51 and 60 Between 41 and 50 Between 31 and 40 Between 21 and 30 Younger than 21

Number of respondents 2 12 45 81 90 74 97 33

Respondents with a partner

79.45%

Living in an urban setting

21.86%

Fig. 1. Personal characteristics of the respondents.

When the perception of risk was analyzed in more detail, about one third of the respondents thought that bricks made from dredged sediments would expose humans to chemical risks (Table 3). In addition, some 12% of respondents did not associate any risk with this type of bricks. Slightly more than half of the respondents (55%) considered the quality of bricks from dredged sediments to be equal to conventional bricks, while 39% thought that the quality would be inferior. The remaining respondents (6%) thought that the quality of bricks from dredged sediments would be better than conventional bricks. However, when the respondents were asked how they would feel about living in a house made from sedibricks, more than 30% showed a negative attitude (Fig. 3). This rather negative perception of the quality of green products was already documented in previous studies (Bhate, 2002; Peattie, 2001).

There is quite some interest in more information concerning bricks from dredged sediments: 31% of respondents would be interested in participating to a workshop with demonstration of these bricks and 43% would be interested in receiving more information through leaflets or newspapers. Still, the majority of the respondents is not interested in the (additional) information regarding these bricks. 5.2. Demand for bricks from dredged sediments Based on the logit models (Table 4), the most significant variables that explained the decision to buy sedibricks were determined. When the price and technical quality of bricks from dredged sediments are equal to conventional commercial bricks, 35.8% of the respondents state that they would buy the bricks from

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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Table 2 Rotated factor loadings and unique variances of characteristics related to environmental beliefs and attitudes. Factor 1 Environmental awareness I am ‘green’ and like to talk about environment issues with friends and family The government should do more for the environment I feel guilty when my behavior is harmful for the environment Compared to other things in my life, environment is not that important A ‘green’ lifestyle is something for people with an alternative lifestyle I find it hard to adapt my lifestyle towards of more environmentally friendly behavior, but I am prepared to do it

0.67 0.66 0.65 0.55 0.47 0.45

Usefulness of taking action I do not believe that my attitude and lifestyle can have an influence on the environment All the hassle about climate change is exaggerated Scientist will find the solution to climate change, making the change in lifestyle and attitude not really necessary

Factor 2

Factor 3

0.45 0.43 0.74 0.72 0.70

Difficulty of taking action I find it hard to adapt my habits and to act more environmentally friendly It requires a lot of effort to behave in more environmentally friendly way

0.84 0.73

Table 4 Different characteristics explaining the likelihood to buy sedibricks, assuming an equal or better technical quality of sedibricks compared to conventional brick.

Fig. 2. Importance of different brick characteristics (respondents could select at most three aspects).

Table 3 Risks related to sedibricks as indicated by the respondents (they could select as many options as they wanted). Risks to humans No risk Chemical risk Radiological risk Biological risk Physical risk Other risk I do not know

Risks to the environment 52 117 31 28 11 4 238

No pollution Soil pollution Water pollution Air pollution Other pollution I do not know

64 64 64 24 5 254

dredged sediments and 64.2% would buy conventional bricks. Respondents already knowing about these bricks (knowbrick in Table 3), having a higher educational degree (higheredu in Table 4) and a higher environmental awareness (factor 1 in Table 3), show a higher likelihood to buy bricks from dredged sediments. This con-

Female Age Knowbrick Child Higheredu Factor 1 Factor 2 Factor 3 Brickrisky Constant

Equal price and quality Coeff. (s.e.)

Equal price and higher quality Coeff. (s.e.)

0.0006 0.0220 0.7082 0.0193 0.4875 0.3524 0.3267 0.1965

0.0869 0.0168 0.6579 0.1444 0.4371 0.0470 0.2521 0.2173 0.6624 2.1065

(0.2353) (0.0080)** (0.3088)** (0.2365) (0.2390)** (0.1204)** (0.1258)** (0.1173)*

0.2342 (0.4090)

(0.2891) (0.0092)* (0.4563) (0.2851) (0.2845) (0.1396) (0.1430)* (0.1343) (0.3154)** (0.5127)

Coeff. = coefficient, s.e. = standard error. ** Significance level < 0.05. * significance level < 0.1.

firms the role of knowledge and information in determining consumer behavior. Older people (Age in Table 4), people with a more fatalistic nature (factor 2 in Table 4) and people who find it difficult to take action for the environment (factor 3 in Table 4) are less likely to buy sedibricks. Again this shows that pro-environmental attitudes are positively correlated with a green consumption pattern. Although some studies indicate a different risk perception towards environmental problems by mothers of newborn babies (Novoselova et al., 2002), this was not confirmed in the present study. Even when the technical quality of sedibricks would be superior to that of conventional bricks, 17.6% of respondents would not be willing to buy the bricks from dredged sediments. Again, older people, people with a fatalistic nature and people associating risks with sedibricks are not likely to buy those bricks. The likelihood to buy these bricks is not affected by gender,

Fig. 3. Attitude towards living in a house built with sedibricks.

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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by the presence of children, by previous knowledge about these bricks, educational degree, environmental awareness (factor 1) and difficulty of taking action (factor 3) (Table 4). To address the willingness to pay for bricks, a multinomial logit model was constructed concerning the following question: ‘‘If the technical quality of sedibricks is equal to the technical quality of conventional commercial bricks, which price are you willing to pay for these sedibricks?’’. Five different possibilities were given: (Category 1) willing to pay more, (Category 2) willing to pay the same price, (Category 3) willing to pay less, (Category 4 = reference category) not willing to pay, and (Category 5) none of the above (Table 5). In general, the model (R2 = 0.0961) indicates that sedibricks that are more expensive than traditional bricks, would be bought by people with a higher environmental awareness (factor 1) and younger people. Several studies (e.g., Kozak et al., 2004) have also shown that a significant share of consumers is willing to pay a price premium for products they perceive to be better for the environment. When there is no price difference between both types of bricks, younger people also indicate that they would buy these bricks, whereas respondents that associate risks with bricks from dredged sediments are not willing to buy these bricks. Finally, when the price of the sedibricks is lower than traditional bricks, mainly younger people are willing to buy the bricks, as well as people who find it difficult to take action for the environment (factor 3). Research (e.g., Anderson et al., 2005) has shown that some consumers will select the product that is perceived to be ‘better for the environment’ if the price is equal to a conventional product. By buying ‘green’ consumers feel good about themselves and this ‘warm glow’ is a stimulant for buying such a green product. When the question ‘‘If the technical quality of sedibricks is higher to the technical quality of conventional commercial bricks, what should be the price difference in order to convince you to buy sedibricks?’’ was asked, young people and people that followed higher education were willing to pay more for sedibricks, while people that associated no risks with these sedibricks and people believing that taking action can improve the environment, were willing to pay the same price. People who find it difficult to take

action for the environment are willing to buy sedibricks if they are sold at a lower price compared to conventional bricks.

5.3. Bricks from dredged sediments: green products? We now briefly discuss whether sedibricks can be promoted as a green product. ‘‘Green products are typically durable, non-toxic, made from recycled materials, or minimally packaged. Of course, there are no completely green products, because they all use up energy and resources and create by-products and emissions during their manufacturing, transport to warehouses and stores, usage, and eventual disposal. So green is relative, describing products with less impact on the environment than their alternatives’’ (Ottman, 1998, p.89). Bricks made from primary raw materials have a significant influence on the environmental impact of a building in its construction phase (Cuéllar-Franca and Azapagic, 2012; Zhang et al., 2013). The use of dredged sediments as an alternative source of raw materials for brick production offers possibilities to lower this environmental impact related to the use of primary resources. The use of labels or environmental product declarations is a promising option to promote the use of bricks made from secondary raw materials. Public institutions can stimulate the manufacturers of building materials to use environmental product declarations in order to provide standardized information to consumers. This information can be based on the LCA of the real impact of every product. The environmental product declarations (EPD), verified by independent entities, can stimulate competition between materials manufacturers to launch more eco-efficient products onto the market. Whereas the focus of buildings with a low environmental impact is mainly on low energy consumption at the moment, the introduction of EPD’s for building materials would be a step forward towards buildings with a real low environmental impact, both from the energy and from the materials point of view (Bribián et al., 2011). Several initiatives already exist on which the regulator could build upon, such as the Green Guide (part of BREEAM (BRE Environmental Assessment Method)), an

Table 5 Different characteristics explaining the willingness to pay for sedibricks. Reference = category 4 = not willing to buy bricks from dredged sediments. Category 1 (WTP price higher) Coeff. (s.e.)

Category 2 (WTP price equal) Coeff. (s.e.)

Category 3 (WTP price lower) Coeff. (s.e.)

Category 5 (other) Coeff. (s.e.)

Female

0.6721 (0.4119)

0.1962 (0.0135)

0.3758 (0.3458)

0.5583 (0.7167)

Age

0.0462* (0.0135)

0.0223* (0.0099)

0.0372* (0.0115)

0.0022 (0.0233)

Brickrisky

0.2415 0.4443

1.0738* (0.3538)

0.2582 (0.3791)

0.3095 (0.8609)

Higheredu

0.6042 (0.4097)

0.4577 (0.2977)

0.0637 (0.3402)

0.0428 (0.7139)

Child

0.8660* (0.4297)

0.1083 (0.2962)

0.4948 (0.3390)

0.9779 (0.7460)

Factor 1

0.6526* (0.2090)

0.1881 (0.1499)

0.0980 (0.1694)

0.2678 (0.3548)

Factor 2

0.2922 (0.2133)

0.1625 (0.1509)

0.2354 (0.1710)

0.1649 (0.3651)

Factor 3

0.1075 (0.1962)

0.1623 (0.1435)

0.4102* (0.1658)

0.3502 (0.3487)

Constant

1.0828 (0.7143)

1.9165 (0.5584)

1.6501 (0.6200)

2.7201 (1.4590)

Coeff. = coefficient, s.e. = standard error. * Significance level < 0.05.

Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025

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accredited environmental rating scheme for buildings, in which commonly used construction materials are assessed. 6. Conclusions Technical problems, such as the dewatering of dredged sediments, have been solved during the last few years, and many different valorisations options, including brick production, have proven to be feasible. Thus, the supply side does not imply specific barriers to stimulate the development of the market for sedibricks. However, the expansion of the demand side of the market seems to lag behind. In Flanders, the real valorisation of dredged sediments is still very limited and consumers are rather suspicious with respect to bricks produced from dredged sediments. Moreover, more than 50% of the respondents indicated that they had insufficient knowledge on this topic, despite the fact that 60% of the respondents had a higher education degree. A correlation between public environmental knowledge and education was nevertheless shown in previous studies (e.g., Arcury and Johnson, 1987; Franzen and Meyer, 2010). The lack of relevant information available among respondents highlights one of the challenges of assessing demand for an innovative, unfamiliar product. While we control for the different factors that can affect consumer attitudes and behavior in the survey design, the reliability of the results cannot be absolutely guaranteed. Still, the results provide an interesting view of the factors that currently dominate consumers attitudes towards sedibricks and it would be interesting to compare the results with a similar study in a different country. Consumer risk perception is mainly determined by the possibility of a bad bargain (brick of inferior quality) and the connotation with chemical contamination. The willingness to pay for bricks made from dredged sediments is mainly influenced by the age of the respondents, as well as their environmental awareness, and the respondents’ belief in their ability to influence environmental problems. Consumers indicate that technical quality, safety and environmental impact are the most important characteristics of building bricks. For this reason sensitization and provision of information to customers are of primary importance to make dredgedsediment-derived bricks a successful product. Environmental certification of building products would be a step forwards in informing consumers on the environmental impacts of bricks. Ultimately, communication on environmental impacts associated with bricks, should be as evident as providing information on technical and safety characteristics. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.wasman.2014.12. 025. References Achour, R., Abriak, N.E., Zentar, R., Rivard, P., Gregoire, P., 2014. Valorization of unauthorized sea disposal dredged sediments as a road foundation material. Environ. Technol. 35 (13–16), 1997–2007. Agostini, F., Skoczylas, F., Lafhaj, Z., 2007. About a possible valorisation in cementitious materials of polluted sediments after treatment. Cem. Concr. Comp. 29, 270–278. Ajzen, I., Joyce, N., Sheikh, S., Cote, N.G., 2011. Knowledge and the prediction of behavior: the role of information accuracy in the theory of planned behavior. Basic Appl. Soc. Psych. 33 (2), 101–117. Anderson, R.C., Laband, D.N., Hansen, E.N., Knowles, C.D., 2005. Price premiums in the mist. Forest Prod. J. 55 (6), 19–22. Arcury, T.A., Johnson, T.P., 1987. Public environmental knowledge: a statewise survey. J. Environ. Educ. 18 (4), 31–37. Bamberg, S., 2003. How does environmental concern influence specific environmentally related behaviors? A new answer to an old question. J. Environ. Psych. 23, 21–32.

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Please cite this article in press as: Cappuyns, V., et al. Dredged sediments as a resource for brick production: Possibilities and barriers from a consumers’ perspective. Waste Management (2015), http://dx.doi.org/10.1016/j.wasman.2014.12.025