Guide to eco-friendly countertops

The aim of this guide to eco-friendly countertops is to identify materials that can be used for a kitchen worktop and meet sustainability and health criteria.

When we began our research, we started by cataloguing all the options available on the market in order to decide which ones we should recommend as suitable for use in our projects.

However, when we began to assess each option by weighing the material’s entire life cycle and its impact on people’s health and the environment, we realised that every material has its pros and cons and, while some options are better than others, there is no ideal material that effectively solves a food-preparation surface.

There are natural materials that meet health, environmental, circular-economy and km0 sourcing criteria, but they are not suitable for guaranteeing the hygiene and health conditions required of a surface intended for food preparation, and therefore require treatments that alter their original properties.

On the other hand, there are materials that may initially seem harmless or low-impact, such as natural stone surfaces—materials that can be sourced locally and with little processing—but which carry a high ecological footprint due to the impact of extraction and shaping processes and, in some cases, present a certain radiological risk.

So, is it better to opt for synthetic products?

Products such as porcelain stoneware or quartz surfaces are engineered composites that offer a wide range of finishes and ensure a high level of hygiene in a food-handling area, but they require binders such as cement, which not only emits CO₂ when limestone decomposes, but also requires firing at extremely high temperatures that can only be achieved using fossil fuels, generating further CO₂ emissions.

So, what is better? Using a stone that we know has a high environmental impact, is non-renewable and, in some cases, may emit radon gas, or using a synthetic material with a high CO₂ footprint?

In the following text, we analyse the wide range of options available when choosing a countertop from many different angles: from basic considerations that directly affect our health, such as the material’s hygiene and safety, to broader and more complex considerations, such as analysing the ecological footprint and life cycle of each material.

This guide to eco-friendly countertops is a comprehensive guide in which we break down all the material options for kitchen worktops, analysing the pros and cons of each. The aim is for the compiled, filtered and reviewed information—supported by suppliers, manufacturers and technical professionals in the sector—to be useful for future builders, designers or users, so they can choose a material based on objective, high-quality information, understanding the environmental and health implications of each choice.

Information sources and technical reviews

To prepare this countertop guide, we consulted various catalogues and reference materials databases at national and international level, which serve as a basis for carrying out life-cycle and impact assessments of products and built environments.

In addition, we contacted different manufacturers, distributors and technical experts who collaborated by providing information, interviews and joint reviews of the text. The full list of collaborators and companies is cited at the end of the text.

Reference catalogues and guides for material assessment

EPA. The United States Environmental Protection Agency develops regulations for previously approved environmental laws. It also carries out outreach work on the environment and health, providing information on a wide range of materials.

Transparency by Perkins&Will. The firm Perkins&Will, founded in 1935, is one of the leading architecture companies internationally, both in revenue and number of employees. Through its Transparency department, dedicated to research and R&D, it has developed a materials database that is constantly updated with internal research and information from suppliers and manufacturers on all kinds of materials and construction products. The so-called Precautionary List provides information on the ecological footprint and toxicity of materials, their composition, and hazards to health and the environment, including details on the chemical composition of each product.

Risctox. This is a Spanish public database developed by the Trade Union Institute for Work, Environment and Health (ISTAS) that compiles all substances considered toxic and hazardous, linking them to a CAS number. It allows data extracted from Safety Data Sheets to be cross-checked, classifying substances according to occupational and environmental exposure limit values, as well as their specific health risks.

Friendly Materials. The Friendly Materials website by PMMT, a firm specialising in healthcare environments that strongly supports research and the dissemination of healthy architecture, analyses materials from a toxicological and life-cycle perspective. The website is fed by materials submitted by the manufacturers themselves.

OpenDap. An official, public and freely accessible database where you can consult or submit Environmental Product Declarations (EPDs) or environmental information on construction products. It is intended to serve as a basis for life-cycle assessment calculation tools. OpenDAP is part of an experimental European-level project aimed at creating a working network that unifies and compiles environmental data through a common standard for data formatting and high compatibility.

Health Product Declaration. HPD is a collaborative, non-profit database for compiling health information on building products. The database is configured to work with programmes from the International Living Future Institute, Cradle to Cradle Product Innovation Institute, Clean Production Action, BIFMA, LEED, WELL and a large number of construction industry certification standards.

Carbon Smart Materials Palette. Developed by Architecture 2030, with support from members of the Embodied Carbon Network (ECN), Carbon Palette is a database that provides a materials specification guide for reducing embodied carbon in the built environment.

1 WOOD

1. Wood

1.1. Solid wood

1.2. Wood-based products

1.3. Bamboo

1.4. Finishes

Wood is the only renewable construction material and is also considered to have a negative ecological footprint, meaning it absorbs more CO₂ than it emits during extraction, transport and processing—provided it is locally sourced and obtained from sustainably managed forests, as guaranteed by the European FSC certificate.

In Spain, local plantations in the north of the country—Galicia, the Basque Country and Catalonia—are usually regulated under the PEFC certification, which controls and tracks timber through the so-called “chain of custody”, ensuring that the wood comes from forests with controlled logging and replanting to guarantee a renewable start-to-finish cycle.

Since 2013, the European Timber Regulation has prohibited the entry into the European Union of timber and timber products from illegal logging. For this reason, the Spanish Timber Trade and Industry Association (AEIM) has developed the Madera Legal website for its member companies. [1]

This is the simplest way to obtain eco-friendly wood through a network of suppliers that certify the material meets controlled and sustainable management criteria.

Wood countertops are not common, as wood is a porous material that requires a surface treatment to seal the pores and ensure maintenance and hygiene. Using a porous material with hygroscopic moisture-regulating properties can be interesting for walls or cladding, but when porosity becomes the material’s main problem, choosing wood as a kitchen worktop becomes purely aesthetic.

Even so, it is a material with a very pleasant, warm appearance, and its porous nature can be mitigated thanks to different synthetic and natural finishing options. Its resistance, ease of cleaning and antibacterial capacity will depend on its surface treatment, which is particularly important in this case. In addition, speaking of reversibility, we should not forget that a sufficiently thick wooden countertop is one of the few materials that, at the end of its service life, can be stripped and reused as new.

Solid wood

The most resistant woods are solid oak and beech, although they are also the most expensive. A more affordable option—though less hard in the case of local types—is pine, which is widely available from locally sourced forests. With pine, it is important to bear in mind that there are around 110 pine species worldwide, so hardness and properties can vary greatly from one variety to another. Another optimal locally sourced wood for countertops is plane tree wood. In Spain, pine is the most widely used, followed by oak and teak.

Due to limitations in material length, special attention must be paid to sealing joints, as water and germs can seep in and cause damp stains. In addition, to avoid marks from impacts and scratches, it is advisable for materials to be as hard as possible.

Wood-based products

Some wood-based products include laminated wood, particleboard or MDF.

Laminated wood

Laminated wood consists of joining wood lamellas so that the fibres run parallel to the axis of the element. By joining pieces together, it is possible to create a wooden element of unlimited length that functions as a single structural unit.

The bond between the pieces that make up the thickness of the countertop material is made with glue, which often contains formaldehyde—a substance considered carcinogenic and neurotoxic above certain concentrations, as it is naturally present in foods and materials at much lower levels. [2] The impact of formaldehyde on human health occurs through the release of VOCs (Volatile Organic Compounds) into the air, and due to its highly volatile nature, formaldehyde is potentially the most harmful substance.

However, these emissions occur mostly during the manufacturing process, which involves high pressures and hot pressing. For this reason, regulations exist to control and limit health risks for workers who manufacture laminated wood panels.

After the manufacturing process, and unless temperature and pressure parameters are modified, emissions are generally very low and may vary depending on the forming process and joint sealing, typically being released through open joints or the edges of pieces.

For this reason, it is always recommended that, to use wood in food-related applications, one or more coats of food-safe varnish be applied to protect the wood’s porosity. Applying varnish remains controversial, as the vast majority of commercial varnishes emit VOCs (Volatile Organic Compounds) that are released into the indoor environment in small amounts for virtually the entire service life of the product.

An alternative is 100% formaldehyde-free single-component polyurethane adhesives, but they are still thermosetting adhesives in which an increase in temperature can lead to the release of toxic vapours. [3]

Particleboard and MDF

On the other hand, there are particleboards and so-called MDF (Medium-Density Fibreboard). Both are materials made from wood waste, so they meet circular economy criteria. In addition, although they are usually bound with synthetic waxes and resins, these can be replaced with natural resins.

These are very economical panels, but they only serve as a base material and require a final finish, as they are porous and not moisture-resistant.

Finishes are usually synthetic plastic laminates—a material that is not only not eco-friendly, but also releases VOCs throughout its service life, scratches easily and does not withstand high temperatures, releasing toxic fumes in the event of abrasion.

Locally, we have very competitive suppliers such as:

Finsa. This company, based in Galicia, pays particular attention to the presence of chemicals harmful to health in binders for wood-based products, as well as to emissions regulations in different countries.

At Finsa, they manufacture a range of MDF panels called NAF that 100% avoid formaldehyde thanks to the use of isocyanate-based adhesives, which earn them the CARB2 (California Air Resources Board) environmental certification—an international standard established by the United States that regulates and limits formaldehyde emissions.

Betanzos HB. Also in A Coruña, Galicia, Betanzos HB offers a product called Tablex, which consists of a high-density wood fibreboard from local forests, 100% eco-friendly and sustainable. Tablex completely avoids the use of glues, based on the idea that instead of using fewer toxic substances to meet regulatory requirements, one can simply stop using them altogether.

Betanzos HB is able to manufacture boards that use no binder external to the wood itself. The forming process is based on separating the raw material into two components: on the one hand, cellulose—the fibres that give wood its structure—and on the other, lignin—the wood’s natural binder. By taking advantage of lignin’s adhesive nature and using a temperature and pressure process, they produce thin fibre particleboards, also known as hardboard, with a maximum thickness of 6 mm and high mechanical and water resistance. The optimal thickness for a kitchen countertop is achieved by bonding several boards together.

Fustes Esteba. This is a local supplier that ensures PEFC certification for its products and works with wood-based products for kitchen countertops.

Cocinas ecológicas. This is a company founded in Huesca that manufactures functional, made-to-measure furniture using wood-based products from local sustainable forests, such as poplar and eucalyptus plywood.

Cocinas ecológicas also uses recycled solid wood, which is interesting because it follows sustainability principles while also applying circular economy criteria, giving a material a second life through reuse. This is a novel type of product and therefore not very widespread in Spain, and many users remain wary of it.

Supply is very limited, so you have to go to Italy to find the nearest supplier. This supplier collects old furniture from various countries, shreds it and manufactures new plywood boards.

Richlite. Another alternative recycled material that we can consider a wood-based product is the patented Richlite, made up of 65% recycled paper and 35% resin, which provides the hardness and closed-pore surface resistance required for a countertop. This paper is FSC-certified and comes in a wide range of colours resulting from combinations of paper with the amber tone of the resins. However, its high resin content consists of phenolic resins with a formaldehyde concentration that, although stated to be below 1.5%, is one of the most harmful biocides to health due to its carcinogenic and neurotoxic effects.

Bamboo

Bamboo is not, strictly speaking, a type of wood, as it is considered a plant rather than a tree, despite having similar characteristics. It is a species of Asian origin with no tradition of production in Spain, and therefore local availability is uncommon.

However, it is important to consider it as a construction material for the near future due to its rapid growth (less than 5 years), which makes it an economical and highly renewable material.

Its rapid growth and reproduction are due to its underground root system, called rhizomes, from which the stems grow. As a single rhizome connects several stems, it is possible to sustainably harvest 25% of the canes annually without reducing the size of the plantation. The rhizome not only does not die after harvesting, but by harvesting mature canes, the yield and quality of the plantation increase.

In addition, its origin makes it harder than oak and pine, and more resistant to moisture due to its tropical plant nature—surpassed only by other tropical species such as ipé wood.

Finishes

As we noted at the start of this guide to eco-friendly countertops, the finish—or lack of one—affects the final performance of a kitchen surface, as the surface layer is what prevents the material from deteriorating or drying out, extending its service life and preserving its properties, appearance, colour, feel, healthiness and hygiene.

Because it is porous, wood absorbs moisture easily, encouraging the growth of bacteria or fungi, which means it cannot guarantee the level of hygiene required for food handling. Therefore, the strategy for protecting wood is to reduce its porosity to turn it into a water-repellent surface. In addition, porosity is directly related to how easy it is to clean and to its waterproofing characteristics.

On the other hand, very hot utensils can leave marks on the surface, so we should always use additional protection.

Natural finishes

Oils and wax

The least invasive and biodegradable options for protecting wood are oils and wax, which penetrate the wood’s pores and saturate them, providing protection and hydration without creating a film, so they require constant maintenance.

If what we are looking for is to waterproof the surface to guarantee hygiene and close the pores, we should opt for waxes that are applied over the board and last for several years.

Oils are the most respectful option for the material, as they keep its breathability and hygroscopic properties intact. The best-known plant-based oils are linseed oil, Tung oil, Danish oil, teak oil and almond oil. Some oils can be bought raw, so there is no need to use a prepared product from a specific brand.

Linseed oil comes from pressed flax seeds and is produced nationally. Other higher-quality options, but of Asian origin—so the carbon footprint of transport should be taken into account—are Tung oil and teak oil, which blends the two. Tung seed provides greater waterproofing even in marine environments and is the most transparent of all. Teak is widely used outdoors due to its resistance to fungi and moisture.

It is important to bear in mind that many of these oils contain components to improve their density and drying time, such as solvents that are harmful to health derived from petroleum or turpentine, an organic solvent distilled from conifers. Without a doubt, checking the full list of components in the oil before application will be essential if we are looking for a natural, toxin-free solution.

There is an oil called food-grade oil that is widely used on woods where food is handled. It is not of natural origin, but a mineral petroleum derivative that undergoes treatments that guarantee it is harmless to health.

Conventional finishes: varnishes

Under the closed-pore category we enter the realm of varnishes, which create a thin surface layer that does not let the wood breathe. Because of this, it is usually recommended to apply a pore sealer beforehand.

There are water-based varnishes, such as water-based polyurethane, which are less aggressive than solvent-based polyurethane and are used on indoor furniture and kitchen surfaces. They are known as very low-emission varnishes and are often used in hospital furniture. They can guarantee the same durability and quality as a conventional kitchen. However, polyurethane’s composition involves exposure to harmful chemical agents such as isocyanates (MDI), which cause irritation, sensitisation and lung damage such as asthma and alveolitis, so their health consequences must be kept in mind.

Another type is so-called food-safe varnishes, which can be in contact with food. These are very durable and are applied in two components: the varnish itself and a hardener. In our country, there is a company that produces them called Cedrià.

There are also paints that can create a waterproof layer over wood, but in this case we not only completely lose the wood’s natural breathability and hygroscopic properties, we also lose the aesthetic quality of exposed wood.

2 STONE

2. Stone

2.1. Natural stone

2.1.1. Marble

2.1.2. Granite

2.1.3. Slate

2.2. Engineered stone

2.2.1. With resin

2.2.2. Without resin

2.3. Terrazzo

Stone is often considered a natural material, but it is not renewable. Certain types of stone took millions of years to form and their extraction requires a lot of energy. However, it is usually one of the most used materials for countertops thanks to its high performance in hardness and heat resistance due to its mineral nature.

Natural stone

Although in practice we could make a countertop from almost any stone, there are two main considerations to bear in mind.

First, the available format, since not all stones allow us to work with large pieces, and this is directly related to the number of joints the work surface will have. We know that in a kitchen, joints are a source of dirt build-up and a breeding ground for microorganisms; the fewer joints we have, the more hygienic the work surface.

Second is porosity, which will determine the need to apply a surface protection layer to the stone. Because of this characteristic, the main drawback of natural stone is the risk of staining from foods such as coffee, oil or vinegar, which can be absorbed by or corrode the material.

Marble

Marble is one of the most noble and common materials for kitchen surfaces; however, it has gradually been replaced by the commercialisation of granite and synthetic materials, which are much more competitive in price and achieve better resistance and durability.

Despite being a stone, marble is a porous material and sensitive to acid stains caused by corrosion. The possibility of these stains is often overlooked, but the reality is that they can come from everyday products such as citrus juice or certain cleaning products.

For this reason, it requires the application of a water-repellent treatment every 6 months, which will imply a higher level of chemical components released into the indoor environment and which may be harmful to health.

Spain is one of the world’s leading marble producers, and most extraction takes place in the quarries of Macael. This is a town in the province of Almería that gives its name to a type of white marble, also known as ‘white gold’ due to its high price. The national company Cosentino currently owns these quarries, making it the largest distributor of this type of marble.

Even though it is a local material, the large amount of energy and resources needed for its extraction make it a material with a high ecological footprint.

Granite

Today, among natural stones, granite is positioned as the most used material for kitchen countertops, as it is more durable than quartz at a similar price. Like marble, granite is extracted, cut and then polished, resulting in a less interesting natural texture and little variety of colours.

Technically, its surface is porous, but to a lesser extent than marble, as it is not as affected by acid stains. In addition, thanks to its polished finish and the possibility of applying products such as waxes, it is practically possible to achieve a closed pore that prevents this type of staining, as well as oil stains.

On the other hand, granite is a type of stone that forms under high pressures beneath the earth’s surface, so it can develop veins of elements such as uranium or thorium, whose presence can vary from stone to stone or even within the same slab. The slow decay of these elements produces an odourless, colourless gas called radon gas, declared by the WHO to be carcinogenic, and which can damage DNA or cause lung cancer. [5]

However, due to the non-porous nature of the material and its surface treatment, which is usually finished with a sealer, granite countertops are not considered a dangerous element, and cases where the concentration is high are unusual. In any case, it is possible to test the air in the home to identify the concentration of radon gas, a measurement that the EPA (United States Environmental Protection Agency) recommends to assess the safety of a granite countertop. [6]

In any case, granite countertops are not considered a key contributor to radiation in the average home. [7]

Slate

Slate is a dark bluish rock characterised by its fissility, an internal structure in the form of sheets or surfaces parallel to each other. Its origin comes from clay layers deposited at the bottom of seas or lakes which, when subjected to great pressure, became the stone we know today.

Due to its structure, different from other natural stones such as marble or granite, slate is not porous but impermeable, and it also has a low heat transmission coefficient. Because of this distinctive property, it has historically been widely used in roof construction. In fact, Spain is the world’s leading slate manufacturer, with export volumes exceeding 80%. Production is concentrated in Galicia, where the Galician Slate Association carried out a study certifying that it is the most natural and sustainable product for roof construction. [8]

The research, carried out in 2013, made it possible to obtain the first national environmental product declaration thanks to the collaboration of the different agents in the sector. It showed that in terms of energy consumption, ceramic tiles use up to 1.7 times more energy and emit 1.5 times more CO₂, while fibre cement reaches 4.5 times. [9]

Pieces that do not have sufficient fissility to achieve the desired thickness for roofing slate make up a secondary market and are used for other purposes such as flooring, tables or kitchen countertops. Their manufacturing process involves primary splitting, sawing and final splitting. Even so, the final finish is never completely smooth; instead, it is characterised by a scaly surface that makes joints between pieces difficult, as the seams do not come out clean.

That is why installing a slate countertop means resolving it as a single piece that is very sensitive to impacts, so it will need to be replaced entirely if it breaks. However, a positive feature is that it does not need any chemical finish as is the case with marble and granite, so it avoids any presence of chemicals.

Engineered stone

Technological stone, or engineered stone, is made from mineral powder in a similar way to wood composites. In terms of performance, whether or not it contains resin has a significant influence, with resin-bonded composites being the first to appear on the market. In recent years, technological advances have made it possible to form materials without adding synthetic materials thanks to overpressure.

With resin

Quartz surface

Quartz is the most abundant mineral on the earth’s surface and consequently the most common material for kitchen countertops thanks to its good value for money.

It is a material that is not marketed in the form of natural quartz slabs, as it is impossible to find it in pure form; rather, it is part of rocks such as granite, which has a 20–60% concentration of quartz, or beach sand, which can be up to 95% quartz. That is why, when we talk about quartz surfaces, also called technological quartz, we are talking about an industrial product made from quartz powder, which usually comes from ground granite.

The best-known commercial product made from technological quartz is Silestone, as it was the first to be developed and patented. It is a material developed in 1990 that revolutionised kitchen companies thanks to its extensive palette compared to the sample range of national granites and marbles. Silestone contains 90–95% quartz, a component harder than granite, bound with a minimal percentage of resin.

These resins are synthetic, adding the presence of toxic substances, and serve a dual purpose: sealing the quartz’s pores and creating an imitation of marble veining. As a result, we get a cladding with minimal joints and a wide variety of colours and finishes at a very attractive price. Other advantages are its antibacterial protection and stain resistance compared to the previous two types, despite its limited resistance to high temperatures due to the resin, which can lead to abrasion marks.

From a health perspective, it is important to bear in mind that silica dust, or crystalline silica, released during cutting or polishing operations of quartz agglomerates—both in workshops producing pieces and during installation—is considered carcinogenic, an endocrine disruptor and neurotoxic according to the WHO’s International Agency for Research on Cancer. No hazards are considered in the case of formed pieces without dust emissions. [10]

Marble agglomerate

Natural marble agglomerate is very similar to quartz surfaces and their properties, as a similar percentage of synthetic resin or cement is used in its composition. Thanks to this mix, a non-porous product with greater hardness is obtained.

It can be produced from crushed marble, or made from sand, soda ash and silica. The first step is to mix the sand and soda ash and heat them to over 1,200°C to melt them. Molten glass, made from silica and pigments that will give the final colouring to the technological marble, is injected later.

As it cools, the mixture is made to descend along metal ramps that cut and cool it, forming spherical marbles that will later be cut. Defective marbles return to production through remelting, enabling recycling and reuse of the material.

As with the rest of industrialised engineered-stone products, it is important to question to what extent some industrial types may have a lower carbon footprint than natural stone, whose extraction involves a high environmental impact.

Recycled glass surface

Following the same logic of a base material with a synthetic binder, we find a wide variety of mineral-based materials, including recycled glass, which can be reused repeatedly and retain its initial capabilities.

To do this, it starts with granulated glass, also called glass powder, obtained by grinding glass to the desired grain size, which has previously been cleaned with water and chemicals. This powder is called cullet. It is then heated to 1,600°C, and may or may not be mixed with more sand, sodium hydroxide and limestone, so the use of high-temperature furnaces is not avoided.

The best-known commercial product based on recycled glass is Obsidiana by the brand Compac, a name that comes from the well-known igneous rock of the same name, which is actually a black volcanic glass. It is made up of mineral-based products in a proportion of between 85 and 95% such as feldspar or glass, plus polyester resin (5–15%) and pigments and additives (<5%). It offers performance similar to other resin-based engineered stones and similar aesthetic possibilities. In addition, due to its low silica content, below 7%, it makes work easier for professionals and allows them to handle the surface more safely, given the carcinogenic nature of the respirable fraction of this component.  

Without resin

On the other hand, there are some engineered stones composed of a large number of different minerals that avoid the presence of resins thanks to manufacturing processes based on the application of high pressures and high temperatures, a process that involves high energy consumption.

Materials that avoid synthetic resins are always harmless to health, as they do not emit VOCs (Volatile Organic Compounds) and also avoid the need to use a water-repellent treatment because they are not porous. These are materials that are resistant to abrasion and acids due to their fully mineral composition, as well as offering greater scratch resistance.

In the case of resin-free agglomerated materials, we have some examples of patented products.

Dekton. The patented material Dekton consists of 20 mineral components in powder form: silicoaluminates, amorphous silica (quartz), crystalline silica, zircon and inorganic pigments. It is a mixture of nanoparticles to which a weight of 25,000 tonnes is applied to form the slabs under pressure. The next step is a high-temperature furnace process at 1,800°C. [11]

This process has high energy consumption because over 30 hours it manages to emulate the earth’s natural formation over thousands of years. In fact, the problem with high-temperature furnaces is that they cannot run on renewable energy, since at present there is no way to reach temperatures above 1,000°C except through fossil fuels such as coal or petroleum derivatives. However, work is being done on the possibility of replacing them with bio-gas. [12] [13]

Lapitec. Another product is the Italian brand Lapitec which, like Dekton, is a full-body sintered stone that allows very large formats, reaching 3.3 m x 1.5 m. In both cases, the material’s advantages come from the manufacturing technology. If we take granite as a reference, most of the material contains a percentage of mica, a soft mineral that reduces its resistance in some areas. However, engineered stone eliminates these drawbacks thanks to the homogeneous mix of components that is agglomerated in high-temperature furnaces, achieving more compact pieces.

In addition, this manufacturing technology allows the pieces to be repairable, so material from slabs that have come out defective can be recovered up to 80% of their composition, following the principles of the circular economy.

Neolith. Composed of 3 groups of elements: minerals from granite, quartz and feldspar that give hardness to the material; minerals from glass and silica that provide chemical stability; and natural oxides used for aesthetic purposes. Neolith is not considered properly recycled, but the percentage of material reuse in its manufacture can range from 10 to 50% depending on the product. It also has Green Guard and Leed certification. [14]

Terrazzo

Terrazzo is considered an artificial stone; however, due to its mineral origin and manufacturing process as a derivative of natural stone in which resin may or may not be used as a binder, as well as its strong tradition and presence in the Spanish market, terrazzo needs to be treated as a category in its own right.

Terrazzo is a construction material made from stone chips and a binder. It first emerged in Venice in the 15th century, with the aim of making use of leftover marble previously used in construction. Traditionally, the binder was made with clay and a layer of goat’s milk for the finish, achieving an appearance similar to marble.

Today, the aggregate can be made up of marble chips, but also leftover glass or granite from construction. The raw material used as a binder can be white cement, obtaining characteristics very similar to concrete, or resins. The resins can be epoxy, polyester resins or latex, allowing easier cleaning, waterproofing and mechanical capabilities, with high impact resistance as it is a more flexible material.

It can be applied in piece format, which is a common installation for flooring, or formed in situ with the creation of shrinkage joints and subsequent polishing. Making a kitchen countertop in situ involves placing the aggregate and pouring the binder, which, if microcement or resins are used, makes it possible to create a continuous surface without any joints thanks to the nature of these binders.

Historically, it has been a material widely used for flooring with tiles, being a very useful investment thanks to its high wear resistance, usually bound with cement. With a large thickness, around 5 cm, it can be polished repeatedly, allowing its use both indoors and outdoors.

Tile manufacturing can be done in two ways: by cutting or moulding. The first consists of forming a large terrazzo block by pouring the binder and aggregates of different sizes and using a vibration process to ensure homogeneous distribution. It is then cut into the different tile pieces with the desired dimensions, which is not as interesting for countertop construction, as it will require joints that will make proper cleaning impossible.

Another option is to manufacture pieces in a mould, so we can achieve larger dimensions, distinguishing the top layer from the bottom one. The top layer contains the mix of aggregate and white cement mixed through with the desired colourant. The bottom, hidden layer of the slab consists of grey cement mixed with sand. Once one layer is placed on top of the other, force is applied with a press so it becomes compact, and it is taken to a sauna with controlled humidity and temperature where the slab will finish curing and acquire the final robustness that characterises it.

Thus, this material adds the ecological impact derived from cement, or the issue of chemicals harmful to health derived from synthetic resins if they are used as a binder. On the other hand, aggregates are not renewable and entail the high energy consumption of their extraction. However, this issue is minimised if recycled aggregates from other materials are used, applying the principles of the circular economy.