NL2033316B1

NL2033316B1 - Ceramic based construction material

Info

Publication number: NL2033316B1
Application number: NL2033316A
Authority: NL
Inventors: Fabian Batenburg Lawrence; Egbertus Carolus Martens Bart
Original assignee: Dakip B V
Priority date: 2022-10-14
Filing date: 2022-10-14
Publication date: 2024-05-03

Abstract

The invention is directed to a construction material, to a method of preparing a construction material, to a method of recycling a construction material, and to a use of ground clay roof tile as a raw material for producing a construction material. The construction material of the invention comprises 50-85 % by total weight of the construction material of ground ceramic and 10-35 % by total weight of the construction material of a thermoplastic polymer.

Description

P133565NL00

Title: CERAMIC BASED CONSTRUCTION MATERIAL

The invention is directed to a construction material, to a method of preparing a construction material, to a method of recycling a construction material, and to a use of ground clay roof tile as a raw material for producing a construction material.

One of the most widely used ceramic raw materials is clay. This inexpensive ingredient found naturally in great abundance, often is used as mined without any upgrading of quality. Another reason that makes clay become popular is because it can be formed easily. With proper proportions during mixing, clay and water form a plastic mass that is very amenable to shaping. The formed piece is dried to remove some of the moisture, after which it is fired at an elevated temperature to improve its mechanical strength. Most of the clay based products fall within two broad classifications which are structural clay products and the white wares.

Structural clay products include building bricks, tiles, and sewer pipes. The white wares ceramics become white after high temperature firing. Included in this group are porcelain, pottery, tableware, china wares and also sanitary wares. In addition to clay, many of these products also contain non-plastic ingredients which influence the changes that take place during the drying and firing processes and the characteristics of the finished piece.

An important application for clay ceramics is in clay-based ceramic roof tiles. The most popular and attractive way of finishing off a roof, in particular a slanted roof is by means of tiles affixed to a base or next-inward roof layer structure such as a sloping wooden framework supported by rafters. In view of possibly harsh weather conditions, the roof tiles should be able to resist, for example, heat, rain, hail, snow, wind and sand storms without damage or tearing off.

From an architectural point of view, types of tiles are also selected for aesthetic reasons. In many countries, clay-based ceramic roof tiles have long since been used, one of the reasons being that the base material (i.e.

clay) has always been readily accessible. Historically, the tiles were shaped by hand, sun-dried and then used on the roof. Nowadays, the manufacturing process is mostly machine-driven, but the finished product is more or less the same. The ceramic tiles are typically sealed to resist absorbing water.

While these ceramic roof tiles have advantageous properties, they also suffer from several disadvantages. For example, ceramic roof tiles are prone to breaking if not carefully worked on. If ceramic roof tiles are blown off from a roof by strong winds they are bound to break on the ground.

Furthermore, in order to provide the ceramic roof tiles with sufficient strength and resistance to breaking, they need to have a relatively high thickness. As a consequence, however, ceramic roof tiles are relatively heavy. As such, a roof with ceramic tiles will need substantial reinforcement to support the extra weight of the clay. The weight also significantly contributes to transportation costs. Additionally, ceramic roof tiles have the disadvantage of absorbing moisture, and therefore typically require sealing.

Further disadvantages of conventional ceramic roof tiles include the tendency of algae and mosses to grow on the tiles, and the extensive amount of dust (fine particle emissions) generated upon sawing and/or drilling.

On top of that, the manufacturing process of clay roof tiles is very time and energy consuming, and harmful for the environment in terms of emissions of carbon dioxide and hazardous fluoride emission. The process of firing the clay in order to provide the tiles with necessary properties requires burning of large amounts of natural gas, which is currently rather expensive.

The typical manufacturing process goes through the stages of mining or quarrying of raw materials, storage of raw materials, raw material preparation, shaping, drying, firing and subsequent treatment.

Special requirements for the surface and colour of the products involve a surface treatment by glazing, englobing or profiling.

The raw clay is mined in large mining pits. After removing the topsoil, mining is usually carried out using shovels. As such, the production contributes to depletion of natural resources.

The mined clay is subsequently sampled and analysed for its ceramic properties and its mineralogical and chemical composition. Based on its ceramic properties, the clay is formed into an operational mass, homogenised and stored. The operational mass may consists of one single clay or more clays, optionally mixed with mineral modifiers such as powdered quartz and feldspar. Further organic and inorganic additives can be added in order to adjust the colour and/or obtain a greater porosity. Such additives may typically include metallic oxides, such as MnO», Fe203, and minerals such as CaCO:. The operational mass 1s then pressed under vacuum in twin-shaft mixers and extruders to form slabs, which are then passed in turret or rotary table presses by means of plaster moulds to form tiles. The operational mass may alternatively be formed in injection moulding machines.

The clay tiles are then dried so as to prepare the tiles for the subsequent firing process. Typically, drying lasts approximately 35 hours at approximately 60-90 °C. Due to shrinking, the ceramic material reacts very sensitively and must be dried under defined conditions. If the tiles are not properly dried, they are at risk of fracture. Accordingly, different drying parameters as well as residual humidity are continuously checked. The dried roof tiles are glazed using a pouring process. Such glazing may also provide a desirable colour.

Subsequently, the clay tiles are fired at approximately 1020 °C in tunnel kilns. The firing time including preheating and cooling is approximately 24 hours. The firing process gives the tiles their ceramic properties, which makes them durable and long-lasting. Even though the firing process can be performed with two levels of tiles in the kiln, and exhaust heat generated by the kiln may be used for drying, the firing process still requires the use of an excessive amount of natural gas.

Moreover, the firing process of ceramic is an important cause of hazardous fluoride emission. Further, the clay tiles so produced may suffer from colour differences due to differences in the original clay composition, causing aesthetic disadvantages.

When dismantling a construction, the ceramic roof tiles are typically collected. Salvaged unbroken roof tiles may be used on another roof, but a considerable part of the collected roof tiles will be damaged.

Broken ceramic roof tiles may be used in road, tennis court or baseball field (gravel) construction, used as landscaping medium, or as decoration, but cannot presently be processed into new ceramic roof tiles.

There are some alternatives for ceramic roof tiles. For example, also slate roof tiles exist. These, however, have the disadvantage of being relatively heavy, and expensive to install, and difficult to handle. Also metal roof tiles are being used. While being light-weight, metal is noisy, dents easily, is extremely dangerous to walk on when wet, and does not provide much insulation value. Another alternative is concrete roof tiles, but like ceramic roof tiles, these require sealant in order to repel water.

Additionally, concrete roof tiles are prone to weathering. Moreover, ceramic roof tiles are highly appreciated for their aesthetic value.

Therefore, some attempts have been made to construct tiles of plastic material having the appearance of clay but which do not have some of the drawbacks. Such plastic tiles are of relatively low weight and generally do not require a specially engineered roof, being able to be installed on standard roof construction. Plastic also has an advantage of being able to be formulated to have a long life. Examples of such plastic tiles are described in amongst others US-A-5 992 116, US-A-5 946 877,

US-A-5 630 305, and US-A-5 615 523.

Also known are roof tile composites of sand and plastics, such as disclosed in e.g. WO-A-2005/078209 and WO-A-2011/135388. Disadvantages of such tiles include that the surface of the tiles can erode, and that they are relatively high weight.

JP-A-2009 046 346 discloses a clay-based ceramic roof tile, wherein an amount of chamotte (a ground fired clay-based ceramic) is 5 blended into unfired clay to form an operational mass that is subsequently fired to produce ceramic roof tiles.

There remains a need in the art for improved construction materials that can be manufactured in an economical fashion and improved ways of recycling existing construction materials.

One objective of the invention is to provide a method for recycling broken or damaged clay roof tiles to form new valuable construction materials, such as roof tiles, preferably in a time and energy efficient manner.

A further objective 1s to provide a ceramic based construction material that does not suffer from being prone to breaking, and/or absorbing moisture.

Yet a further objective is to provide a ceramic based construction material that can easily be handled, processed into a desirable shape, and/or sawn without generating excessive amounts of dust.

The inventors found that one or more of these objectives can be met by providing a composite construction material of ground ceramic and a thermoplastic polymer.

Accordingly in a first aspect, the invention is direct to a construction material comprising 50-85 % by total weight of the construction material of ground ceramic and 10-35 % by total weight of the construction material of a thermoplastic polymer.

The term “ceramic” as used herein is meant to refer to a class of inorganic, non-metallic products which are subjected to a temperature of 540 °C or more during manufacture or use, and it includes metallic oxides, borides, carbides, or nitrides, and mixtures or compounds of such material.

The term “clay” as used herein is meant to refer to clay as won from a clay-pit which clay generally comprises a clay mineral fraction and a “non-clay” fraction, the definition also extending to modified clays, that is, “clay” as won to which or from which proportions of “clay minerals” and/or non-clay fractions have been added or removed.

The term “fired” as used herein in the context of firing clay is meant to refer to clay having been subjected to its “peak firing” temperature and is in the process of being cooled to ambient temperature or has been so cooled.

The term “peak firing temperature” as used herein is mean to refer to the temperature to which a product must be raised for develop a microstructure necessary for the end product, e.g. a fired clay roof tile, to possess adequate properties, e.g. weather resistance. The peak firing temperature depends on the composition of the product. Typically, however, the peak firing temperature is a temperature of 550 °C or more, such as 750 °C or more, 900 °C or more, or 1000 °C or more.

The inventors found that a high quality construction material can be produced from ground ceramic by compounding with a thermoplastic polymer. The construction material advantageously has extremely good mechanical properties, in particular a high impact strength, such that the material will not easily break. For instance, a roof tile prepared from the construction material can be dropped without breaking. Furthermore, the material can advantageously be processed, such as by sewing, cutting or chipping, without producing excessive dust, but only generating acceptable powder.

Moreover, the invention advantageously comprises ceramic (material that has been fired, i.e. subjected to the peak firing temperature) as a raw material, for example a fired clay composition that may advantageously originate from a recycle stream. The raw material hence already possesses desirable properties, and the production of the construction material of the invention does not require an additional firing step. As a result, the construction material of the invention can be formed at relatively low temperatures (such as less than 250 °C), thereby for example consuming only a fraction of the energy required for the preparation of conventional ceramic. Manufacture of the construction material of the invention does not require mining of clay.

Another advantage is that the construction material does not (or hardly) absorb moisture. Recycling is extremely easy, since the construction material can be shredded, ground, heated, and formed into new construction material. Furthermore, due to its excellent mechanical properties, the construction material can be hollow, thereby requiring much less raw material and yielding a construction material of significantly less weight.

The invention thus provides for a construction material that may be produced at least partially using raw material from a recycle stream and that has desirable properties that can outperform the original material. For instance, the construction material may be produced using ground clay-based ceramic roof tiles to yield a ceramic roof tile with enhanced properties. Bonding of elements of the construction material can be achieved by simple heating without the need for additional adhesive, such as two-component adhesive.

Furthermore, the construction material of the invention is highly resistant to growth of mosses and algae, and can be produced with a high degree of colour evenness.

The ground ceramic can have a particle size in the range of 1-1000 microns, such as 5-900 microns, 10-800 microns, 20-700 microns, 30-600 microns, or 40-500 microns.

The ground ceramic preferably comprises a clay-based ceramic.

Different types of clay exist. The most industrially used clay minerals are kaolinite, smectite, palygorskite, and sepiolite.

Kaolinite is a 1 : 1 clay mineral with chemical formula

SuAl:O1(OH)s. The ideal structure of kaolinite has no charge. Hence, the structure of kaolinite is fixed due to the hydrogen bonding. There is no expansion between the layers when the clay is wetted. Kaolinite does not swell in water and has relatively low surface areas and cation exchange capacity.

Smectite clays are mainly based on either a trioctahedral 2 : 1 or a dioctahedral 2:1 structure and differ from the neutral kaolinite structures due to the presence of isomorphous substitution in the octahedral or tetrahedral layer. The smectite group of clay minerals are further divided into saponites (trioctahedral) and montmorillonite (dioctahedral). Another important member of the smectite family is bentonite. Bentonite clay is also known as sedimentary clay and has unique property of water retaining. The flake-like crystals of smectite consist of an expanding lattice. Each layer is composed of an octahedral sheet sandwiched between two tetrahedral sheets. Slight attraction is found between oxygen atoms present in the bottom tetrahedral sheet of one unit and in the top tetrahedral sheet of another unit. This allows a variable space between layers, which 1s occupied by exchangeable cations and water. The exchangeable cations and water can easily enter the interlayer space resulting in the expansion of layers that may vary from 9.6 to 20 A. The general structural formula of smectite clay is (Na,Ca)o.23(ALMg)2S140 10(OH)2: (HO). The structure, chemical composition, exchangeable ions are responsible for their several unique properties such as high cation exchange capacity, high surface area and high adsorption capacity.

The clay-based ceramic may be based on clay comprising kaolinite and/or smectite.

Suitably, the clay may have a cation-exchange capacity at pH 7 of 70-130 milliequivalents per 100 grams, such as 80-120 milliequivalents per

100 grams. The clay can have a specific surface area of 20-1000 m?/g, such as 30-900 m?/g or 40-800 m?/g.

The ground ceramic preferably is a structural ground clay-based ceramic, that is a ceramic that is used for structural clay products. The ground ceramic preferably comprises ground clay-based ceramic roof tile.

The ground ceramic may further comprise structural ground clay-based ceramic originating from brick, sewer pipe, and/or paving stone. Preferably, 75 % or more by total weight of the ground ceramic in the construction material consists of ground clay-based ceramic roof tile, such as 85 % or more, 90 % or more, 95 % or more, or 98 % or more.

The ground ceramic is present in the construction material in an amount of 50-85 % by total weight of the construction material, such as in an amount of 50-80 %, in an amount of 55-80 %, in an amount of 55-75 %, or in an amount of 60-75 %.

The thermoplastic polymer may comprise one or more commodity polymers. Such polymers may, for instance, be selected from the group consisting of polyethylene (PE) (including LDPE, MDPE and HDPE), polypropylene (PP) (homopolymer and copolymers), polystyrene (PS), polyvinylchloride (PVC), poly(methyl methacrylate) (PMMA) and copolymers thereof. The thermoplastic polymer may, alternatively or in addition, comprise one or more bio-based thermoplastic polymers. Examples thereof include lignin and poly(lactic acid) (PLA). The thermoplastic polymer may also, alternatively or in addition, comprise one or more biodegradable thermoplastic polymers. Examples thereof include polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(lactic acid) (PLA), and polyhydroxy alkanoates (PHA), such as PHBH (a random copolymer of (R)-3-hydroxybutyrate and (R)-3-hydroxyhexanoate).

The thermoplastic polymer preferably comprises polypropylene, polybutylene adipate terephthalate, or a combination thereof. The term polypropylene in this context includes propylene copolymers, such as propylene/a-olefin copolymer, having a comonomer content of up to 60 mol%, such as 20-60 mol% or 30-60 mol%. More preferably, the propylene copolymer is a propylene/ethylene copolymer.

Preferably, the thermoplastic polymer has a melting point (According to ASTM D3418) and/or a Vicat softening point (according to

ISO 306) in the range of 100-250 °C, such as 110-240 °C, 120-230 °C, or 130-220 °C. The thermoplastic polymer can further suitably have a melt flow index of 1-50 g/10 min (at 230 °C and 2.16 kg), such as 2-45 g/10 min, 3-30 g/10 min, 4-25 g/10 min or 5-20 g/10 min.

The thermoplastic polymer is present in the construction material in an amount of 10-35 % by total weight of the construction material, such as in an amount of 15-35 %, in an amount of 15-30 %, or in an amount of 20-30 %.

It is advantageous if the construction material comprises, in addition to the above-mentioned thermoplastic polymer, a maleic anhydride grafted polyolefin that acts as a compatibiliser, such as a maleic anhydride grafted polyethylene or polypropylene, preferably a maleic anhydride grafted polypropylene. The presence of such maleic anhydride grafted polyolefin improves the mixing of the different components including the ground ceramic and the thermoplastic polymer.

Such maleic anhydride grafted polyolefin may have a melt index as measured at 190 °C, under 1.2 kg load and using a die 8/1 of 10-45 g/10 min, such as 15-40 g/10 min, 20-35 g/10 min, or 25-30 g/10 min.

The maleic anhydride grafted polyolefin may be present in the construction material in an amount of 3-10 % by total weight of polymer material, such as in an amount of 4-9 %, or in an amount of 5-8 %. The skilled person will be able to determine the optimum amount of maleic anhydride grafted polyolefin depending on the particle size of the ground ceramic.

Optionally, the construction material may comprise one or more additives. Such additives may suitably be selected from the group consisting of ultraviolet blocking agents, blowing agents, antioxidants, processing aids, colourants (including pigments and/or dyes), fillers, antibacterial agents, release agents, heat stabilisers, light stabilisers, compatibilisers, inorganic material additives, surfactants, coupling agents, impact-reinforcing agents, lubricants, weather-resistant agents, adhesion aids, adhesives, and any combination thereof.

Examples of suitable ultraviolet blocking agents include titanium dioxide, carbon black, and combinations thereof.

Examples of suitable blowing agents include azodicarbonamide, expandable microspheres, p-p'-oxy-bis(benzenesulphonylhydrazide), p-toluene sulphonyl semicarbizide, sodium bicarbonate, citric acid, and any combination thereof.

If present, the amount of the blowing agents can be 5 % or less by total weight of the construction material, preferably in the range of 0.01-4 %, more preferably in the range of 0.05-3 %.

Examples of suitable processing aids include metal salts of carboxylic acids, such as zinc stearate or calcium stearate, fatty acids, such as stearic acid, oleic acid or erucic acid, fatty amides, such as stearamide, oleamide, erucamide or N,N'-ethylene bis-stearamide, polyethylene wax, oxidised polyethylene wax, polymers of ethylene oxide, copolymers of ethylene oxide and propylene oxide, vegetable waxes, petroleum waxes, non-ionic surfactants, fluoropolymers, such as polytetrafluoroethylene and the like, and polysiloxanes.

The amount of the processing aids can be 5 % or less by total weight of the construction material, preferably in the range of 0.05-5 %, more preferably in the range of 0.1-3 %.

Examples of suitable pigments include carbon black, titanium dioxide, barium sulphate, iron oxide, and any combination thereof.

The amount of the pigments can be 10 % or less by total weight of the construction material, preferably in the range of 0.5-10 %, more preferably in the range of 1-5 %.

Examples of suitable dyes include organic dyes, such as coumarins, lanthanide complexes, hydrocarbon and substituted hydrocarbon dyes, polycyclic aromatic hydrocarbons, scintillation dyes (preferably oxazoles and oxadiazoles), aryl- or heteroaryl-substituted poly(C».s olefins), carbocyanine dyes, phthalocyanine dyes and pigments, oxazine dyes, carbostyryl dyes, porphyrin dyes, acridine dyes, anthraquinone dyes, arylmethane dyes, azo dyes, diazonium dyes, nitro dyes, quinone imine dyes, tetrazolium dyes, thiazole dyes, perylene dyes, perinone dyes, bis-benzoxazolylthiophene, xanthene dyes, and any combination thereof.

The amount of the dyes can be 5 % or less by total weight of the construction material, such as 0.1-5 %, 0.2-4 %, 0.3-3 %, or 0.5-2 %.

Examples of suitable fillers include carbon black, wollastonite, solid microspheres, hollow microspheres, kaolin, clay-based minerals, bauxite, calcium carbonate, feldspar, barium sulphate, titanium dioxide, talc, pyrophyllite, quartz, natural silica, such as crystalline silica and microcrystalline silica, synthetic silicates, such as calcium silicate, zirconium silicate and aluminium silicate, including mullite, sillimanite, cyanite, andalusite and synthetic alkali metal aluminosilicates, microcrystalline novaculite, diatomaceous silica, perlite, synthetic silica, such as fumed silica and precipitated silica, antimony oxide, bentonite, mica, vermiculite, zeolite, and combinations of metals with various salts, such as calcium, magnesium, zinc, barium, aluminium combined with oxide, sulphate, borate, phosphate, carbonate, hydroxide and the like, and any combination thereof.

It is preferred that the amount of fillers (such as carbon black) is 10 % or less by total weight of the construction material, such as 1-8 %, or 2-5 %.

Examples of suitable antioxidants include hindered phenols, such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, bis[(B-(3,5-di-tert-butyl-4-hydroxybenzyl)-methylcarboxyethyl)] sulphide, 4,4'-thio-bi1s(2-methyl-6-tert-butylphenol), 4,4'-thio-bis(2-tert-butyl-5-methylphenol), 2,2 '-thio-bis(4-methyl-6-tert-butylphenol), thiodiethylene b1s(3,5-di-tert-butyl-4-hydroxy)hydrocinnamate, phosphites and phosphonites, such as tris(2,4-di-tert-butylphenyl)phosphite and di-tert-butylphenyl-phosphonite, thio compounds, such as dilaurylthiodipropionate, dimyristylthiodipropionate and distearylthiodipropionate, various siloxanes, polymerised 2,2 4-trimethyl-1,2-dihydroquinoline,

N‚N'-bis(1,4-dimethylpentyl-p-phenylenediamine), alkylated diphenylamines, 4,4'-bis(a,a-dimethylbenzyl)diphenylamine, diphenyl-p-phenylenediamine, mixed di-aryl-p-phenylenediamines and other hindered amine antidegradants or stabilisers, and or any combination thereof. Both primary and secondary antioxidants may be applied. Primary antioxidants function as radical catchers and particularly remove peroxyl radicals (ROO*) and, to a lesser extent, alkoxy radicals (RO*), hydroxyl radicals (HO*), and alkyl radicals (R*). Oxidation begins with the formation of alkyl radicals, which react rapidly with molecular oxygen and thus form peroxyl radicals. Secondary antioxidants particularly remove organic hydroperoxides (ROOH) formed by the effect of primary oxidants.

Hydroperoxides are less reactive than radicals, but undergo hemolytic bonding and break new radicals.

The amount of the antioxidants can be 5 % or less by total weight of the construction material, preferably in the range of 0.1-5 %, more preferably in the range of 0.2-3 %.

Examples of the weather-resistance agents include benzophenone-type weather resistance agents, amine-type weather resistance agents, and combinations thereof.

The total amount of additives is preferably 10 % or less by total weight of the construction material, such as 0.1-10 %, 0.2-8 %, 0.3-5 %, or 0.5-3 %.

The amount of unfired clay in the construction material of the invention is preferably low, because this will negatively influence the mechanical properties of the material. Hence, the amount of unfired clay is preferably 5 % or less by total weight of the construction material, more preferably 2 % or less, even more preferably 1 % or less, and most preferably, the construction material is essentially free from unfired clay.

The construction material of the invention can have a bulk density of 1.5 to 3 kg/m3, such as 1.8 to 2.5 kg/m3, or 2.0 to 2.4 kg/m’. This density is slightly lower than the bulk density of conventional ceramic construction material. If the density of the construction material is too low, then its mechanical properties, and in particular its strength, will be adversely affected.

The construction material of the invention can further have a porosity of 20 % or less, such as 10 % or less, 1 to 18 %, 2 to 15 %, or 4-12 %.

A high degree of porosity may cause penetration of water, thereby deteriorating the properties of the material. For example, the material may become more brittle.

Suitably, the construction material has a water absorption of less than 10 % or less, such as 5 % or less, or 2 % or less, such as 1-2 %. Water absorption may be determined, e.g., according to ASTM D570, or alternatively with thermogravimetric analysis (TGA).

The construction material may have any suitable form. Suitable forms of construction material include a roof tile, a plate, a sheet, a corrugated sheet, a brick, a brick slip, a facade panel, a system panel, or the like. Preferably, the construction material is in the form of a roof tile, a brick, or a brick slip.

The construction material of the invention has a high degree of freedom of form. This allows the creation of unconventional forms and/or the provision of special technical features.

For example, the construction material may advantageously be a hollow construction material. The hollow construction material can have one or more cavities, surrounded by walls. In this way, a construction material 1s provided that has excellent mechanical properties while much less raw material is needed. Furthermore, it allows the production of a light-weight construction material, which is highly advantageous for example in view of transportation. Additionally, the presence of air or the like in the one or more cavities of the hollow construction material may contribute to improved insulation value of the construction material. Optionally, the one or more cavities in the hollow construction material may be filled with an insulating material and/or a material that improves the acoustic properties of the construction material (for example reduces the sound of rainfall on a roof tile). Examples of such material include expanded polystyrene, mineral wool, polyurethane foam, and phenolic foam, expanded vermiculite, hemp.

The hollow construction material may, e.g., have an average wall thickness of 1-12 mm, such as 2-11 mm, 3-10 mm, 4-9 mm or 5-8 mm.

Other possibilities include, for example, the provision of ditches and/or channels in the construction material that may be used, e.g., for cooling by water or for electrical wiring. In this manner, it would for example be possible to provide ceramic-based roof tiles having ditches and/or channels that allow cooling of the roof by running water therethrough.

It is also possible, that the construction material is provided with one or more holes that may be used, e.g., in fixing the construction material to an underlying and/or adjacent structure.

Yet a further possibility is the addition or integration of a solar foil (i.e. a photovoltaic foil) to the construction material. Such a foil may readily be added during the production process of the construction material during forming. The invention accordingly in an embodiment provides solar construction elements (such as facade panels, system panels, roof tiles, sheets, etc.) comprising a construction material of the invention and a solar foil.

In a further aspect, the invention 1s directed to a method of preparing a construction material comprising - providing ground ceramic; - mixing the ground ceramic with a thermoplastic polymer to provide a mixture at a temperature above the melting temperature of the thermoplastic polymer; - forming the mixture at a temperature above the melting temperature of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer.

The ground ceramic may suitably comprise ground clay-based ceramic. Preferably, said providing ground ceramic comprises grinding clay-based ceramic roof tile. Optionally, the step of providing ground ceramic may be preceded by a step of crushing ceramic, such as crushing clay-based ceramic roof tile.

The ceramic is preferably ground to have an average particle size in the range of 1-1000 microns, such as 5-900 microns, 10-800 microns, 20-700 microns, 30-600 microns, or 40-500 microns.

Grinding the ceramic may, for instance, be performed in a pulveriser, such as a ball mill. Optionally, the ground ceramic may be subjecting to sieving in order to remove larger aggregates.

Suitably, the ground ceramic is subjected to a drying step before being mixed with the thermoplastic polymer. Such a drying step may involve drying for 1-4 hours at a temperature in the range of 60-90 °C, such as 70-80 °C. Drying can suitable be performed in an oven, such as a tunnel oven.

The ground ceramic is then mixed with thermoplastic polymer to provide a mixture. Such mixing can suitably be performed in an extruder (such as a double screw extruder) or a mixer (such as a compounder). The mixing is performed at a temperature above the melting temperature of the thermoplastic polymer. The mixing temperature, hence depends on the type of thermoplastic polymer that is employed. Preferably, the mixing temperature is 250 °C or less, such as 100-250 °C. By means of example, in case of a polypropylene polymer the mixing can be performed at a temperature in the range of 100-250 °C, such as 150-240 °C, 170-230 °C, or 180-220 °C. Preferably, the mixing/blending is performed on a twin-screw extruder and with a mild mixing screw. The extrusion time will typically vary between 20 seconds until 1 minute depending on the extrusion flow rate (kg/h).

In a subsequent step, the mixture may be formed at a temperature above the melting temperature of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer. This may suitably be done by pressing in a mould. Suitable moulding machines include a press moulding machine or an extrusion moulding machine. After moulding, the construction material is typically cooled down and ejected/removed from the mould. Also for thinner products, like brick slips and thin roof tiles, a sheet can be extruded and forms can be punched into a roof tile or brick strip.

In yet a further aspect, the invention is directed to a method of recycling a construction material of the invention, preferably a roof tile, comprising - collecting construction material according to the invention; - grinding the construction material;

- heating the mixture above the melting temperature of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer; and - forming the mixture.

After grinding of the construction material, it may be optionally be mixed with additional thermoplastic polymer. Suitably, forming the mixture is performed at a temperature above the melting temperature of the thermoplastic polymer and/or above the Vica softening point of the thermoplastic polymer. Preferably, the temperature is 250 °C or less, such as 100-250 °C.

The mixture may be formed into any suitable form of construction material such as a roof tile, a plate, a sheet, a corrugated sheet, a brick, a brick slip, a facade panel, a system panel, or the like. Preferably, the mixture 1s formed in the form of a roof tile.

At any time after having formed the mixture into the construction material, the construction material may be heated above the melting temperature of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer in order to additionally form the construction material. An example thereof can be the forming of a construction material by bending, or the like. It is, for instance, possible to form the mixture into a brick slip, which brick slip can subsequently be heated in order to bend it over curved surfaces.

The thermoplastic polymer in the methods of the invention can be a thermoplastic polymer as previously described herein.

Suitably, the thermoplastic polymer can additionally comprise a maleic anhydride grafted polyolefin as previously described herein.

The forming may suitably be done by means of three dimensional additive fabrication (3D printing).

Preferably, in the method of the invention, the mixture is formed in the form of a roof tile. The method advantageously allows to prepare all formed construction materials, such as roof tiles, in the same manner. This, for instance, enables the coverage of roofs not only with even colour distribution, but also with even discolouration over time (which may be challenging with conventional clay-based ceramic roof tiles).

In yet a further aspect, the invention is directed to the use of ground clay-based ceramic roof tile as a raw material for producing a construction material, such as a roof tile, said construction material further comprising thermoplastic polymer, wherein said construction material is produced at a temperature above the melting temperature of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer. Preferably, the construction material is produced at a temperature of 250 °C or less, such as 100-250 °C.

In accordance with this aspect, ground clay-based ceramic roof tile is used as raw material for the preparation of new construction material. It thus provides an advantageous recycle for end of life clay-based ceramic roof tile. Moreover, the new construction material is upgraded with respect to the original clay-based ceramic roof tile, e.g. of in terms impact properties, water absorption, processability (ability to saw), etc. In addition, the preparation of the new construction material requires much less energy than the preparation of the original clay-based ceramic roof tile.

Preferably, the construction material comprises 50-85 % by total weight of the construction material of the ground clay ceramic roof tile and 10-35 % by total weight of the construction material of the thermoplastic polymer.

All references cited herein are hereby completely incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (z.e., meaning “including, but not limited to”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein.

Variation of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject-matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.

For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

The invention will now be illustrated by the means of the following example.

Example

Used clay-based ceramic roof tiles were crushed and ground to powder. The ground clay-based ceramic roof tiles were sieved by a 35-40 mesh sieve (0.50-0.42 mm). The ground ceramic powder was subsequently dried for 4 hours at 80 °C to remove moisture.

Dried ground ceramic powder was then added to molten polymer in a double screw extruder using a dosing apparatus. The weight ratio between ground ceramic and polymer was 75 : 25.

The polymer fraction contained 95 % by total weight of polymer material of a propylene copolymer (Polypropylene C715-12N HP, obtained from Braskem) having a Vicat softening point (ISO 306) of 152 °C and a density of 0.900 g/cm? (ISO 1183-1). The propylene copolymer had a melt flow index of approximately 12 g/10 min (at 230 °C and 2.16 kg; ISO 1133).

The polymer fraction further contained 5 % by total weight of polymer material of a maleic anhydride grafted polypropylene which acts as a compatibiliser (PRIEX* 20097, obtained from Byk), having a melting point of 160-164 °C. The maleic anhydride grafted polypropylene compatibiliser had a melt flow index of 25-30 g/10 min (at 190 °C and 2.16 kg using a die 8/1).

The extruded compound was formed into a roof tile by injecting it into a mould and forming the roof tile under pressure at a temperature of 210 °C.

The formed roof tile had a weight comparable to a complete ceramic roof tile of the same size and shape, and comparable colour.

However, the formed roof tile had surprisingly improved mechanical properties as compared to the conventional ceramic roof tile, in particular toughness.

The roof tile of the invention could be dropped from significant height (3 m) without breaking.

Additionally, the tile could be readily sawn and chipped, unlike a conventional ceramic roof tile.

Claims

Conclusions

1. Construction material that comprises 50-85% of the total weight of the construction material of ground ceramic and 10-35% of the total weight of the construction material of a thermoplastic polymer.

A construction material according to claim 1, wherein said ground ceramic has a particle size in the range of 1-1000 microns.

A construction material according to claim 1 or 2, wherein said ground ceramic comprises a clay-based ceramic.

4. Construction material according to claim 3, wherein said clay is kaolin clay and/or smectite clay, optionally combined with one or more coloring agents.

5. Construction material according to any one of claims 1-4, wherein said ground ceramic comprises ground ceramic roof tile.

6. Construction material according to any one of claims 1-5, wherein said thermoplastic polymer comprises one or more polymers selected from the group consisting of raw material polymers such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), poly (methyl methacrylate) (PMMA) and copolymers thereof; bio-based polymers such as lignin and poly(lactic acid) (PLA); and biodegradable polymers such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(lactic acid) (PLA), and polyhydroxyalkanoates (PHA).

A construction material according to any one of claims 1 to 6, wherein said polymer comprises polypropylene, polybutylene adipate terephthalate, or a combination thereof.

A construction material according to claim 6 or 7, wherein said polymer further comprises maleic anhydride grafted polypropylene.

9. Construction material according to claim 8, wherein the maleic anhydride grafted polypropylene is present in an amount of 5-15% by total weight of the construction material.

10. Construction material according to claim 8 or 9, wherein said maleic anhydride grafted polypropylene has a melt index as measured at 190 °C, under 1.2 kg load and with a die 8/1 of 10-45 g/10 min, such as 15-40 g /10 min, 20-35 8/10 min, or 25-30 g/10 min.

11. Construction material according to any one of claims 1-10 in the form of a roof tile, a plate, a sheet, a corrugated sheet, a stone, a stone strip, a facade panel, or a system panel, preferably in the form of a roof tile, a stone or a stone strip.

12. Construction material according to any one of claims 1-11, wherein said construction material is a hollow construction material.

13. Construction material according to claim 12, wherein said hollow construction material has an average wall thickness of 2-10 mm.

14. Method for preparing a construction material comprising - providing ground ceramic;

- mixing the ground ceramic with a thermoplastic polymer above the melting point of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer to provide a mixture; - forming the mixture at a temperature above the melting point of the thermoplastic polymer and/or the Vicat softening point.

The method of claim 14, wherein said ground ceramic comprises clay-based ceramic, and wherein providing ground ceramic includes grinding clay-based roof tile.

16. Method according to claims 14 or 15, wherein said ground ceramic has a particle size of 1-1000 microns.

Method for recycling a construction material according to any one of claims 1-13, preferably a roof tile, comprising - collecting construction material according to any one of claims 1-13; - grinding the construction material and optionally mixing the construction material with additional thermoplastic polymer; - heating mixture above the melting point of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer; and - forming the mixture at a temperature above the melting point of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer, preferably in the form of a roof tile.

Method according to any one of claims 14-17, wherein said thermoplastic polymer comprises one or more polymers selected from the group consisting of raw material polymers such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), poly (methyl methacrylate) (PMMA) and copolymers thereof; bio-based polymers such as lignin and poly(lactic acid) (PLA); and biodegradable polymers such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly({lactic acid) (PLA), and polyhydroxyalkanoates (PHA), preferably said polymer comprises one or more of polypropylene and polybutylene adipate terephthalate.

The method of any one of claim 18, wherein said thermoplastic polymer further comprises maleic anhydride grafted polypropylene.

A method according to any one of claims 14-19, wherein said forming comprises three-dimensional printing.

21. Use of ground ceramic roof tile as raw material for producing a construction material, such as a roof tile, further comprising thermoplastic polymer, wherein said construction material is produced at a temperature above the melting temperature of the thermoplastic polymer and/or above the Vicat softening point of the thermoplastic polymer, preferably at a temperature of 250°C or less.

Use according to claim 21, wherein said construction material comprises 50-85% by total weight of construction material of the milled ceramic roof tile and 10-35% by total weight of construction material of the thermoplastic polymer.