WO2025032268A1 - Prefabricated element for construction and associated method - Google Patents

Abstract

The present invention relates to a prefabricated element (1) for construction that comprises a binder (2) and an aggregate (3) that are based on gypsum (21) and calcium sulphate (31), and includes a retardant (9) additive (5). The manufacturing method comprises the steps of i) preparing a calcium sulphate-based (31) aggregate (3); ii) homogeneously mixing a gypsum (21) binder (2), the calcium sulphate-based (31) aggregate (3) and water (4); and iii) forming the prefabricated element (1) by means of vibro-compression, in order to produce new material for construction, providing enhanced energy efficiency performance, and CO₂ emissions, with the possibility of using recycled materials and additions, ultimately avoiding the need to use cement when forming a prefabricated part.

Description

DESCRIPTION

PREFABRICATED ELEMENT FOR CONSTRUCTION AND ASSOCIATED METHOD

OBJECT OF THE INVENTION

The present patent application aims to protect a prefabricated element for construction comprising at least one binder and at least one aggregate, where the binder is gypsum, and the aggregate is based on calcium sulphate plus a retarding additive. It also aims at a method of manufacturing said prefabricated element for construction, with the steps of i) preparation of an aggregate based on calcium sulphate; ii) homogeneous mixing of a gypsum binder, the aggregate based on calcium sulphate and water; iii) shaping of the prefabricated element by means of vibro compression, incorporating notable innovations and advantages.

BACKGROUND OF THE INVENTION

Currently, calcium sulphate-based manufacturing developments, such as plaster, brown or black construction plaster, white plaster, anhydrite, etc., are based on the pouring system. This way of working has proven to be efficient for certain applications, for example, for the manufacture of false plaster ceilings, the creation of decorative pieces, etc. This way of working requires specific moulds that can be made of different materials, as well as sometimes long setting times that make manufacturing performance slow. In addition, the result obtained, due to the quantity of kneading water necessary to obtain the fluid paste, causes the manufactured element to have fragile mechanical properties, the resulting material being porous, soft, easily permeable to water, etc.

An illustrative document of what is known in the state of the art would be that described in patent SU645607A, which discloses a construction block made from gypsum aggregates and a PVC coating. Specifically, a manufacturing process for elementary gypsum-based construction material is described, which has the general shape of a rectangular prism, where the prepared gypsum block is embedded in a compact or light polyvinyl chloride profile, with a strictly defined section, and is cut to the desired length. Said gypsum block, thus profiled and made, is covered in its two free ends, by means of two bottoms of the same plastic material, of dimensions substantially equal to the straight section of the profile and welded at its ends.

On the other hand, it is known from the state of the art that patent RU1774935C describes a method of manufacturing products based on gypsum and concrete, from the mixture of gypsum binders and gypsum aggregates, where the gypsum binder is mixed with recycled gypsum aggregates and other additives. They can also be mixed, however, with cement. And in order to increase resistance to water and frost, it includes mixing dosed construction gypsum and water, placing the resulting mixture in a mould, followed by a stage of suction, stripping and drying.

Thus, and in view of all the above, there is still a need to obtain a new material for the construction sector, providing better energy efficiency, reducing CO2 emissions in its production, and also providing the option or possibility of using recycled materials and additives, ultimately avoiding the need to use cement when forming a prefabricated piece.

DESCRIPTION OF THE INVENTION

The present invention aims to define a new prefabricated element, as well as its manufacturing method, following a vibro compression system, using gypsum as raw material as a binder, and aggregates based on calcium sulphate.

This procedure is preferably intended for the manufacture of prefabricated elements, which covers the entire base of prefabricated elements by vibrocompression obtained using the traditional system of cement plus aggregates; blocks, vaults, curbs, paving stones, caissons, prefabricated elements in general, using calcium sulphate as a base with a formulation based on gypsum with retardant additives, and different proportions of aggregates or mineral fillers, previously manufactured from calcium sulphate itself.

The aim is therefore to achieve a semi-dry mix, i.e. a plaster with a low contribution of hydration water, which reduces the mixing water, while using retarding and fluidifying additives. It should be noted that a mix is understood as a low hydration mass. The quantity of water required to be added to the hemihydrate to convert it into a dihydrate is of the order of 186 g of water per 1000 g of gypsum. This quantity does not allow any workability unless the gypsum is already partially hydrated. Thus, we start from a basis of reducing the carrier water to a minimum of about 200±10 grams of water per 1000 g of gypsum for this purpose. The gypsum to be used is extended to any hemihydrated type, and makes high dehydration temperatures unnecessary, since it is not necessary to exceed 160“C. In this new material, it is also extended to ao alpha type gypsum, white gypsum, and plasters.

In the present invention two phases are defined, the quantity of water of which, starting from the minimum indicated, varies according to the phase of the process described below:

I) First phase of the process - Manufacture of gypsum aggregate: For this, it is necessary to obtain an aggregate as a basis for development. From calcium sulphate, aggregates are manufactured as a basis for the vibrocompression manufacturing system, with gypsum as the main base material. For this manufacture, the water is reduced to 185±10 g of water per 1000 g of gypsum, adding to the mixing water or to the gypsum itself, the necessary retarding base, optionally citric acid (polycarboxylic) and/or critical acid with silicon dioxide. For the mixing system, the use of a planetary mixer or another mixing system that forms the agglomerates of the so-called gypsum aggregate is feasible.

Once the aggregate has been manufactured, it is passed through a sieve to remove the coarse aggregates, which can be used by using a hammer mill with a sieve grid at the outlet to reduce the particle size to a maximum of 5-8 mm. This particle size is determined by the walls of the piece to be manufactured according to the mould of the vibrocompression machine.

Regarding the production of crushed gypsum aggregate without cooking, it is worth mentioning that the extraction of gypsum involves a protocol that depends on how the material is found in nature, according to different qualities and forms. The extracted material is taken to a first phase of coarse grinding that is carried out with crushers or hammer mills. The size of the particles requires a second process of crushing or grinding to obtain a finer size, less than 10 mm. On the other hand, not all the rocks extracted have the same quality, and the aggregate must be classified before using it as a filler material in the second phase described below. II) Second phase of the process - Mixing aggregates with gypsum: The aggregate is added to the gypsum according to a defined percentage. For mixing, for example using a planetary mixer, the water is increased up to a total of 210-240g for every 1000g of gypsum, and can reach up to 300g of water depending on the quality of the gypsum. Likewise, either the water or the gypsum plus aggregate mixture must be added.

III) Third phase of the process - Pouring into the vibrocompression machine: The pieces are shaped according to the mould used, giving way to a natural drying period of between 24 and 72 hours, depending on the relative humidity of the environment, although after 10-20 minutes it can be palletised, thus considerably reducing the space used for manufacturing.

In view of the above, it is considered to be different from everything known in the state of the art, that the prefabricated element of the present invention contains aggregates based on calcium sulphate, prepared from rapid setting and a low contribution of water in the water/gypsum ratio, and a subsequent elimination of very large and very small particles, by filtering, dehydration, respectively, for their subsequent use. Thus, both the binder and the aggregates are based on calcium sulphate, using for manufacturing a vibrocompression process, with dry pouring, so the amount of water used is less than in pouring by casting. In this way, a prefabricated element is obtained with a process that consumes less energy, less water, and reduces CO2 emissions. On the other hand, the prefabricated element, being manufactured with aggregates based on calcium sulphate, has thermal, acoustic, or fire resistance properties, greater than traditional concrete or ceramics.

In more detail, the prefabricated element for construction comprises at least one binder and at least one aggregate, where the binder is gypsum, and the aggregate is based on calcium sulphate plus a retarding additive. The prefabricated element may be understood as, but is not limited to, curbs, paving stones, bricks, vaults, blocks, presenting a compressive strength of between 14 and 20 N/mm ² .

It should be noted that the retarding additive, or retarder, can be used mixed in the final water, although it can also be added dry. To adjust the dosage, especially when recycled aggregates are added or when the manufacture of gypsum aggregates is not homogeneous, procedures can be established, depending on the dispersion and size. of manufactured aggregates, as well as their granulometric classification, such as the Bolomey or Fuller method.

It should be noted that the use of gypsum with mineral aggregates means a reduction in CO2 emissions, with the achievement of better thermal, acoustic or fire resistance properties, surpassing those of traditional concrete or ceramics. Thus, the invention changes the concept of using gypsum as a pouring element to that of dry pouring. The advantage of this new material and the construction piece is that it does not require the use of cement, with the consequent environmental advantage of reducing the latter by gypsum, since in the manufacture of a piece a very significant lesser manufacturing energy is used compared to conventional materials that comprise, for example, cement. In addition, gypsum is an element considered ideal for the circular economy, since it is 100% reusable.

It should be added that the use of calcium sulphate-based aggregate allows it to be integrated into the matrix without modifying the properties that qualify the plaster, without reducing its physical properties such as heat transmission, fire resistance, etc. And once mixed with a low hydration plaster, and once vibrated, it is possible to reduce the pressing pressure on the walls of the mould, given that said aggregates are incompressible elements.

Preferably, the weight of the binder is between 40% and 70% of the weight of the prefabricated element, which translates into a weight of 400g to 700g of the total 1000g of the prefabricated element, thus presenting optimized properties in terms of mechanical and thermal resistance. Specifically, the increase in mechanical compressive strength, taking cast black plaster as a reference, is 2N/ ^mm and can reach values of up to 20N/mm2, which represents an increase of 1000%.

In addition, the weight of the aggregate is between 30% and 60% of the weight of the prefabricated element, which translates into a weight of 300 g to 600 g of the mixture out of the total of 1000 g of the prefabricated element, thus presenting optimized properties in terms of mechanical and thermal resistance. Specifically, the coefficient of thermal variation X (kcal/hm K or W/m ^a . ^a C) is reduced by more than 30%. Optionally, the binder is one of the group of black plaster, white plaster, plaster or alpha plaster, which provides a degree of flexibility to the mixture, with alternatives of possible constituent materials.

Additionally, the aggregate is one of the group of prefabricated aggregate, recycled aggregate, gypsum aggregate directly from the quarry without cooking treatment, or a mixture of prefabricated aggregate with recycled aggregate, which also provides a degree of flexibility to the mixture, with alternatives of possible constituent materials.

It should be noted that it is therefore possible to mix with an additional portion of recycled aggregates, which may include gypsum, as well as aggregates made from ceramics, such as in the specific case of arlite or perlite. The different types of aggregates are focused on different applications, depending on their quality, as well as the content or mixture of said aggregates. Recycled aggregates are understood to be those that are the result of the treatment of inorganic materials that have previously been used in construction. Therefore, they are construction and demolition waste.

The type of aggregate used is also determined by the particle size fraction sought in the final mixture, preferably a fine aggregate of no more than 8 mm, that is, sand or gravel, discarding gravel and ballast. Recycled aggregates from concrete are basically obtained from foundations, building structures, prefabricated elements, etc. The use of aggregates from asphalt agglomerate layers and other recycled aggregates from clean ceramic waste and aggregates from mixtures is also contemplated. Aggregates from concrete are the most suitable due to their mechanical properties, although aggregates from clean ceramic waste and aggregates from mixtures can be chosen. Its maximum quantity is up to 70%, also depending on the quality of the plaster and its purity.

More specifically, the prefabricated aggregate for the prefabricated element for construction comprises a granulometry of i) maximum size of 10 mm, with a presence of between 1% and 5%; i¡) size between 3-5 mm, with a presence of between 75% and 88%; iii) size between 0.2-0.05mm, with a presence of between 10% and 20%; iv) size between 0.02- 0.005mm, with a presence of between 1% and 5%; and further comprises between 17.36% and 23.08% of water of the weight of the prefabricated element and between 0.01% and 0.2% of additive of the weight of the prefabricated element, where the additive is based on a polycarboxylic acid. This granulometry is defined according to the Attemberg classification, thus presenting optimized properties in terms of mechanical and thermal resistance, in line with what was mentioned above.

It should be noted that the first phase involves the prefabrication of aggregates based on a material based on gypsum or calcium sulphate with very low hydration. The characteristics of the prefabricated aggregate are those of an incompressible material with low water absorption, due to a closed capillary structure. This is achieved through rapid setting and a low water contribution in the water/gypsum ratio.

The second phase of the manufacturing process to obtain the prefabricated element consists of obtaining a homogeneous mixture of the aggregates with the rest of the gypsum matrix. Due to the low water absorption, the amount of water needed for the mixture will vary, although the final water in this step is estimated between 210-300g for every 1000g of gypsum. In the case of plaster, this percentage varies due to the better properties of the same compared to construction plaster. The percentage of hydration could be higher, depending on the purity and degree of grinding, reaching a contribution that can exceed 300 grams, that is, 250-350 g for every 1000 g of plaster.

As a general summary of the precast element material, a general dosage of the material comprises a) 400 - 700 g of gypsum, which may be black gypsum, white gypsum, plaster of Paris or gypsum; b) 300 - 700 g of aggregate, which may be precast aggregate based on calcium sulphate, gypsum aggregate selected from quarry extraction, recycled aggregate or a mixture of precast gypsum aggregate with recycled aggregate; c) 210 - 300 g of water; d) 0.1 - 2 g of water additive based on polycarboxylic acids.

Preferably, the polycarboxylic acid is citric acid or citric acid with silicon dioxide, and also a melamine compound and/or salts, for example citric acid with a melamine base and/or salts, all with the aim of adding a retarding additive that delays setting.

In a preferred embodiment of the invention, the recycled aggregate comprises a granulometry of i) maximum size of 10 mm, with a presence of between 1% and 8%: ii) size between 3-5 mm, with a presence of between 68% and 88%; lii) size between 0.2-0.05mm, with a presence of between 8% and 21%; iv) between 0.02-0.005mm, with a presence of between 1% and 6%. This recycled aggregate has the advantage of being more environmentally sustainable.

Additionally, the prefabricated aggregate can be based on a single particle size distribution of i) maximum size of 10 mm, with a presence of between 0% and 10 %; ii) size between 3-5 mm, with a presence of between 0% and 100 %; iii) size between 0.2-0.05 mm, with a presence of between 0% and 100 %; iv) size between 0.02-0.005 mm, with a presence of between 1% and 10 %; , and also comprises between 17.36% and 23.08% of water by weight of the prefabricated element and between 0.01% and 0.2% of additive by weight of the prefabricated element, where the additive is based on a polycarboxylic acid, a methamine compound and/or salts, thus presenting optimized properties in terms of mechanical and thermal resistance. Specifically, the increase in compressive strength can reach 700% (from 2 N/mm ^í to 14 N/mm ^¿ ), with thermal properties also improving by 20% depending on the fraction used.

On the other hand, the aggregate comprises a proportion of up to 30% of arlite or perite, plus prefabricated aggregate, given that recycled aggregates can be added. Thus, the proportion of prefabricated aggregate supplied can be replaced by a fraction of said recycled aggregate. The gypsum matrix admits up to a maximum of 70% of aggregate in the matrix without counting the water, although these aggregates reduce the properties of calcium sulphate, therefore, it is considered that a reasonable fraction can be 10%-40% of recycled aggregate with respect to 100% of the aggregate, or of arlite or perite.

As for the fractions or granulometry of these recycled aggregates, they preferably have the proportions of: a) 10 mm gravel in 1 - 8 %; b) fine gravel 5-3 mm in 68 - 88 %; c) fine sand 0.2-0.05 in 8 - 21 %; d) silt 0.02-0.005 in 1 - 6 %. being aggregates from crushed or concrete waste, from clean ceramic waste or aggregates from a mixture of both.

The present invention also relates to a method of manufacturing a prefabricated element for construction, which comprises the steps of: i) preparing an aggregate based on calcium sulphate; ii) homogeneous mixing of a gypsum binder, the aggregate based on calcium sulphate and water; iii) shaping the prefabricated element by means of vibro compression, such that a prefabricated element is obtained that is suitably shaped as described above. It should be noted that vibrocompression in gypsum and/or calcium sulphate significantly reduces handling time when compared to vibrocompression in concrete. It also does not require a curing chamber or the addition of additional water. It should be noted that the manufactured aggregate is added to the gypsum for subsequent vibrocompression, since vibration eliminates part of the air in the mixture and the cavities, the vibration process being a fundamental part of the matrix fixing process, which consists of homogenising said aggregates.

It should also be mentioned that, after laboratory tests, when trying to obtain parts in moulds subjected to a compression process, said compression implies a considerable increase in lateral pressure on the matrix; that is, perpendicular to the pressure pushing the mixture on the mould. This pressure prevents or greatly hinders subsequent demoulding, and prevents the possibility of obtaining thin walls, that is, between 0.5-20 mm, complicating the manufacture of parts whose height in the compression direction exceeds 150 mm. The incorporation of gypsum aggregate solves this problem, making it feasible to manufacture prefabricated elements, using pressure and vibrocompression.

It should be noted that the method of manufacturing prefabricated elements for construction involves the addition of a water additive based on a polycarboxylic acid or silicon dioxide.

In a preferred embodiment of the invention of the method of manufacturing prefabricated elements for construction, the preparation of a mixture comprising an aggregate based on calcium sulphate, water and additive and comprising a part of aggregates, recycled aggregates, quarry aggregates, ahite or perlite, and comprises the steps of: i.1) mixing the calcium sulphate with water, additive and aggregates; i.2) kneading said mixture of calcium sulphate with water, additive and aggregates in a rotary horizontal mixer until obtaining calcium sulphate grains of homogeneous size less than 8 mm; i.3) pouring the mixture into a vibro compression machine to obtain the prefabricated elements, so that the prefabricated elements obtained with said process have a compressive strength greater than between 14 and 20 N/mm ^? . Please note that the horizontal mixer can be a rotary mixer with blades or pickaxes, and that there is a screening stage to remove coarse aggregates, i.e., diameters greater than Bmm. It should be noted that different manufacturing processes can be used to obtain these aggregates. For example, with a horizontal mixer with paddles or pickaxes, or simply planetary type mixing machines. In the first case, a higher quality of aggregates is achieved, since the plaster, once in the vat, is sprayed with water, previously added with a setting retarder.

The rotating blades continuously mix, forming balls or grains of homogeneous size and diameters less than 7 mm. The initial quantity of water is set at 185±10 g per 1000 g of gypsum. In the case of the planetary machine, the balls or grains are not usually homogeneous and a subsequent screening is necessary to eliminate the coarse fraction. In the case of adding polycarboxylic acids to the water, for example, with citric acid, this is set between 0.1-2 g per 1000 g of gypsum to be mixed.

Additionally, the preparation of an aggregate based on calcium sulphate comprises a prior stage of obtaining treated water for mixing, where the treated water comprises a setting retarder, so that the mixing water already includes said component.

Additionally, the preparation of a calcium sulphate-based aggregate comprises the following steps: i.1) mixing the calcium sulphate with water and additive; i.2) pulverizing the mixture of calcium sulphate with water and additive in a rotary horizontal mixer until obtaining a calcium sulphate grain of homogeneous size; i.3) sieving the calcium sulphate aggregate with a diameter less than 8 mm; i.4) grinding the calcium sulphate grains with a diameter greater than 10 mm in a fragmentation mill; i.5) dehydration treatment of the calcium sulphate.

It should be noted that in this case the horizontal mixer can be a rotary mixer with blades or pickaxes. That screening involves removing aggregates with a thickness greater than desired, in this case with diameters greater than 8 mm. That the grinding of the grains, or gravel, of aggregate in a fragmentation mill is to eliminate the largest particles, and to reduce the granulometry to a maximum of 5-8 mm, and that they can be reused in smaller fractions. And that the dehydration treatment of calcium sulphate is to eliminate the smallest particles, to be reused again in the production of the aggregate. And that the aggregates obtained with the previous procedure have a shore C hardness of 98-100, a humidity absorption of less than 0.1 -0.5% and a compressive strength greater than 20 N/mm ² . It should also be noted that, in order to produce vibro-compressed pieces, the filler material requires screening and/or sifting to remove silt and fine sand smaller than 0.1 mm, as well as gravel exceeding 7 or 8 mm in average particle diameter. In this sense, the larger particles can be subjected to a fragmentation mill to be reused in smaller fractions, and the fine particles can be subjected to a calcium sulphate dehydration process to be reused again in the production of the aggregate. Thus, 100% of the gypsum is used, which is quite an achievement, something that is not usually achieved in the known industrial manufacturing processes of construction materials.

More specifically, the amount of water is between 14.89% and 17.01% of the weight of the prefabricated element, thus presenting optimized properties in terms of mechanical and thermal resistance. Specifically, the increase in compressive strength can reach up to 1000% (from 2 N/mm ² to 20 N/mm ^z ), also improving thermal properties by up to 30%, depending on the type of part manufactured.

The attached drawings show, by way of non-limiting example, a prefabricated element for construction, and associated method, constituted in accordance with the invention. Other characteristics and advantages of said prefabricated element for construction, and associated method, object of the present invention, will be evident from the description of a preferred, but not exclusive, embodiment, which is illustrated by way of non-limiting example in the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1- View of various prefabricated elements for construction, in accordance with the present invention;

Figure 2- View of a container with the mixture of various materials according to the manufacturing method of the prefabricated element, in accordance with the present invention;

Figure 3- View of a container with the resulting grain-shaped aggregate according to the manufacturing method of the prefabricated element, in accordance with the present invention;

Figure 4- View of a container filled with aggregate as well as the raw material obtained according to the manufacturing method of the prefabricated element, in accordance with the present invention;

Figure 5- Perspective view of a mixing machine, according to the present invention;

Figure 6- Perspective view of a mill that receives the aggregate and transforms it into grain, in accordance with the present invention;

Figure 7- View of the addition of a retarder on water mixed with calcium sulphate-based aggregate, in accordance with the present invention;

Figure 8- View of the various elements that make up the manufacturing method of the prefabricated element, in accordance with the present invention;

DESCRIPTION OF A PREFERRED EMBODIMENT

In view of the aforementioned figures and, in accordance with the numbering adopted, one can observe in them a preferred embodiment of the invention, comprising the parts and elements that are indicated and described in detail below.

Figure 1 shows a view of several prefabricated elements (1) for construction, forming a wall.

Figure 2 shows a view of a container with the mixture of various materials according to the manufacturing method of the prefabricated element (1), specifically an aggregate (3) with a retarder (9), together with a binder (2) with a gypsum base (21), to which water (4) is added with at least one additive (5). Figure 3 shows a view of a container with the result of an aggregate (3) in the form of grain (6) according to the manufacturing method of the prefabricated element (1).

Figure 4 shows a view of a container filled with aggregate (3) as well as the raw material from which it is obtained according to the manufacturing method of the prefabricated element (1).

Figure 5 shows a perspective view of a mixing machine (7).

Figure 6 shows a perspective view of a mill (8) that receives the aggregate (3) and transforms it into grain (6).

Figure 7 shows a view of the addition of a retarder (9) to water (4) mixed with aggregate (3) based on calcium sulphate (31).

Figure 8 shows a view of the various elements that make up the manufacturing method of the prefabricated element (1), consisting of a binder (2) with a gypsum base (21), on the other hand an aggregate (3), to which water (4) is added with some additive (5), preferably a retarder (9), with the help of a mixing machine (7) and a mill (8). with the functionalities and according to the stages and phases described above.

By way of illustration, and not limitation, four examples of the invention are set out below, which would give rise to a prefabricated element (1) with the properties and features explained above:

Example 1:

700 g of black plaster, white plaster, plaster of paris or plaster of paris

300 g of prefabricated aggregate

- 240 g of water

- 1 g of polycarboxylic acid, e.g. critical acid

Example 2:

- 400 g of black plaster, white plaster, plaster of paris or plaster of paris

- 600 g of prefabricated aggregate/selected aggregate from gypsum quarry

- 240 g of water - 1 g of polycarboxylic acid, e.g. critical acid

Example 3:

- 700 g of black plaster, white plaster, plaster of paris or α plaster

- 240 g of prefabricated aggregate/selected aggregate from gypsum quarry

- 60 g of recycled aggregates and/or arlite

- 240 g of water

- 1 g of polycarboxylic acid, e.g. critical acid

Example 4:

- 400 g of black plaster, white plaster, plaster of paris or plaster of paris

- 480 g of prefabricated aggregate/selected aggregate from gypsum quarry

- 120 g of recycled aggregates and/or arlite

•• 240 g of water

- 1 g of polycarboxylic acid, for example, critical acid.

More particularly, as seen in Figures 2 and 8, the prefabricated element (1) for construction comprises at least one binder (2) and at least one aggregate (3), where the binder (2) is gypsum (21), and the aggregate (3) is based on calcium sulphate (31) plus a retarder additive (5) (9).

Preferably, as seen in figures 1 and 2, the weight of the binder (2) is between 40% and 70% of the weight of the prefabricated element (1).

Additionally, as can be seen in figures 1 and 2, the weight of the aggregate (3) is between 30% and 60% of the weight of the prefabricated element (1).

It should be noted that, as seen in Figures 1 and 2, the binder (2) is one of the group of black gypsum (21), white gypsum (21), plaster or alpha gypsum (21).

On the other hand, as can be seen in figures 3 and 4, the aggregate (3) is one of the group of prefabricated aggregate (3), recycled aggregate (3), gypsum aggregate (3) directly from the quarry without cooking treatment, or a mixture of prefabricated aggregate (3) with recycled aggregate (3). As an example, it can be stated that in a preferred embodiment of the invention, as regards the recycled aggregate (3), the maximum quantity is between 10% and 40% of the 100% of the aggregate (3), 600g would be binder (2), i.e. 60%, and 400g of prefabricated aggregate (3), i.e. 40%, out of a total of 1000g. As regards the aggregates (3) from mixtures, the maximum quantity would be up to 70% of the 100% of the aggregate (3), 600g would be binder (2), and 280g of recycled aggregates (3), together with 120g of prefabricated aggregates (3), out of a total of 1000g.

According to another aspect of the invention, as seen in Figures 3 and 4, the prefabricated aggregate (3) comprises a granulometry of: i) maximum size of 10 mm, with a presence of between 1% and 5%; ii) size between 3-5 mm, with a presence of between 75% and 88%; iii) size between 0.2-0.05mm, with a presence of between 10% and 20%; iv) size between 0.02-0.005mm, with a presence of between 1% and 5%; , and further comprises between 17.36% and 23.08% of water of the weight of the prefabricated element (1) and between 0.01% and 0.2% of additive of the weight of the prefabricated element (1). where the additive (5) is based on a polycarboxylic acid.

It should be noted, as an example, that in a preferred embodiment of the invention, as regards the prefabricated element (1), 600g would be binder (2), 400g of prefabricated aggregates (3), that is, 40%, out of a total of 1000g, with 5% of these aggregates (3) being of a size smaller than 10mm, 80% of a size of 3-5mm, 10% of a size between 0.2-0.05, 5% of a size of 0.002-0.005. It should be mentioned that the contribution of between 17.36% and 23.08% of water (4) of the weight of the prefabricated element (1), corresponds to between 210g and 300g of water (4). with 1000g of gypsum (21) plus additional aggregate (3), reaching a final composition of between 1210 and 1300g. Additionally, between 0.01% and 0.2% of additive (5) of the weight of the prefabricated element (1), on the 1000g of gypsum (21) plus aggregate (3), represents between 0.1 and 2g of additive (5).

In more detail, as shown in Figure 2, polycarboxylic acid is citric acid or citric acid with silicon dioxide, and alternatively citric acid based on melamine and/or salts.

It is worth mentioning that, as can be seen in figures 3 and 4, the recycled aggregate (3) comprises a granulometry of: i) maximum size of 10 mm, with a presence of between 1% and 8%; ii) size between 3-5 mm, with a presence of between 68% and 88%; iil) size between 0.2-0.05mm, with a presence of between 8% and 21%; iv) between 0.02-0.005mm, with a presence of between 1% and 6%.

Optionally, as seen in figures 3 and 4, the prefabricated aggregate (3) can be based on a single granulometry of: i) maximum size of 10 mm, with a presence of between 0% and 10 %; ii) size between 3-5 mm, with a presence of between 0% and 100 %; iii) size between 0.2-0.05 mm, with a presence of between 0% and 100 %; iv) size between 0.02-0.005 mm, with a presence of between 1% and 10 %; and further comprises between 17.36% and 23.08% of water (4) of the weight of the prefabricated element (1) and between 0.01% and 0.2% of additive (5) of the weight of the prefabricated element (1), where the additive (5) is based on a polycarboxylic acid, a melamine compound and/or salts.

Specifically, a prefabricated element (1) can have 600g of binder (2), 400g of prefabricated aggregates (3), 40% of which is over 1000g, and 100% of these aggregates (3) being between 3-5mm in size. Alternatively, a prefabricated element (1) has 600g of binder (2), 400g of prefabricated aggregates (3), that is, 40% of 1000g, with 240g, that is, 60% of aggregates (3) of size between 3-5mm, and 160g, that is, 40% of aggregates (3) of size between 0.2-0.05. It should be noted that the preferred percentages of 17.36% and 23.08% of water (4) of the weight of the prefabricated element (1), correspond to 210g and 300g of water (4), with 1000g of gypsum (21) plus additional aggregate (3), going to a final composition of a weight of between 1210d and 1300g. From the above, we have percentages between 0.01% and 0.2% of additive (5) of the weight of the prefabricated element (1), on the 1000g of plaster (21) plus aggregate (3), which represents 0.1-2g of additive (5)

In a preferred embodiment of the invention, as shown in Figures 3 and 4, the aggregate (3) comprises a proportion of up to 30% of arlite or perite, plus prefabricated aggregate (3). Thus, as regards the recycled aggregate (3), the maximum quantity is between 10% and 40% with respect to 100% of the aggregate (3). And as regards the arlite aggregates, it has up to 70% with respect to 100% of the aggregate (3).

The present invention also relates, as shown in Figure 8, to a method of manufacturing a prefabricated element (1) for construction, which comprises the steps of: i) preparing an aggregate (3) based on calcium sulphate (31); ii) homogeneous mixing of a binder (2) of gypsum (21), the aggregate (3) based on calcium sulphate (31) and water (4); forming of the prefabricated element (1) by means of vibro compression. Thus, as for the raw material, prefabricated aggregates (3) of calcium sulphate (31) are used.

Preferably, as seen in Figure 2, the method of manufacturing the prefabricated element (1) for construction, comprises the addition of a water additive (5) (4) based on a polycarboxylic acid, or with silicon dioxide.

It should be noted that, as seen in figure 8, the method of manufacturing a prefabricated element (1) for construction, comprises the preparation of a mixture comprising an aggregate (3) based on calcium sulphate (31), water (4) and additive (5) and comprising a portion of aggregates (3), recycled aggregates (3), quarry aggregates (3), arlite or perlite, and comprises the steps of: 1) mixing the calcium sulphate (31) with water (4), additive (5) and aggregates (3); 2) kneading said mixture of calcium sulphate (31) with water (4), additive (5) and aggregates (3) in a horizontal rotary mixer (7) until obtaining grains (6) of calcium sulphate (31) of homogeneous size less than 8 mm; i.3) pouring the mixture into a vibro compression machine to obtain the prefabricated elements (1).

Additionally, as seen in figures 2 and 7, the preparation of an aggregate (3) based on calcium sulphate (31) comprises a prior stage of obtaining treated water (4) for mixing, where the treated water (4) comprises a setting retarder (9).

Additionally, as shown in Figure 8, the preparation of an aggregate (3) based on calcium sulphate (31) comprises the following steps: i.1) mixing the calcium sulphate (31) with water (4) and additive (5); i.2) pulverizing the mixture of calcium sulphate (31) with water (4) and additive (5) in a horizontal rotary mixer (7) until obtaining a grain (6) of calcium sulphate (31) of homogeneous size; i.3) sieving the aggregate (3) of calcium sulphate (31) with a diameter less than 8 mm; i.4) grinding the grains (6) of calcium sulphate (31) with a diameter greater than 10 mm in a fragmentation mill (8); i.5) dehydration treatment of the calcium sulphate (31).

More specifically, as can be seen in figures 2 and 7, the amount of water (4) is between 14.89% and 17.01% of the weight of the prefabricated element (1). Specifically, between 175g and 205g of water (4), which, with the additional 1000g of gypsum (21) plus aggregate (3), the final composition would end up having between 1175 and 1205g. It should be added that to obtain these aggregates (3) different manufacturing procedures can be chosen. For example, a mixer (7) horizontal paddle mixers or pickaxes, or simply planetary type mixing machines. In the first case, the most interesting for the quality of the aggregates (3), the gypsum (21) once in the vat is subjected to a spray of water (4), previously added with a setting retarder (9). The rotating paddles mix continuously forming balls or grains (6) of homogeneous size and diameters less than 7mm. The initial quantity of water (4) is set at 185120 g for every 1000 g of gypsum (21), resulting in a weight of 1175 g of mix (1000 g + 175 g), 14.89% of mix, and for 1205 g (1000 + 205 g), 17.01% of mix.

In the case of the planetary machine, the balls or grains (6) are not homogeneous, and a subsequent screening is necessary to eliminate the coarse fraction. In the case of adding water (4) with polycarboxylic acids, for example, with citric acid, this is set between 0.1-2g for every 1000g of gypsum (21) to be mixed.

The details, shapes, dimensions and other accessory elements, as well as the components used in the implementation of the prefabricated element (1) for construction, and associated method, may be conveniently replaced by others that are technically equivalent, and do not deviate from the essence of the invention or the scope defined by the claims included below the following list.

List of numerical references:

1 prefabricated element

2 binder

21 plaster

3 arid

31 calcium sulfate

4 water

5 additive

6 grain

7 mixer

8 mill

9 retarder

Claims

1- Prefabricated element (1) for construction comprising at least one binder (2) and at least one aggregate (3), characterized in that the binder (2) is gypsum (21), and the aggregate (3) is based on calcium sulphate (31) plus a retarder additive (5) (9). 2- Prefabricated element (1) for construction, according to claim 1, characterized in that the weight of the binder (2) is between 40% and 70% of the weight of the prefabricated element (1). 3- Prefabricated element (1) for construction, according to any of the preceding claims, characterized in that the weight of the aggregate (3) is between 30% and 60% of the weight of the prefabricated element (1). 4- Prefabricated element (1) for construction, according to any of the preceding claims, characterized in that the binder (2) is one of the group of black plaster (21), white plaster (21), plaster or alpha plaster (21). 5- Prefabricated element (1) for construction, according to any of the preceding claims, characterized in that the aggregate (3) is one of the group of prefabricated aggregate (3), recycled aggregate (3), gypsum aggregate (3) directly from the quarry without cooking treatment, or a mixture of prefabricated aggregate (3) with recycled aggregate (3). 6- Prefabricated element (1) for construction, according to claim 5, characterized in that the prefabricated aggregate (3) comprises a granulometry of: - maximum size of 10 mm, with a presence of between 1% and 5%; - size between 3-5 mm, with a presence of between 75% and 88%; - size between 0.2-0.05mm, with a presence of between 10% and 20%: - size between 0.02-0.005mm, with a presence of between 1% and 5%; , and also comprises between 17.36% and 23.08% of water of the weight of the prefabricated element (1) and between 0.01% and 0.2% of additive of the weight of the prefabricated element (1), where the additive (5) is based on a polycarboxylic acid. 7- Prefabricated element (1) for construction, according to claim 6, characterized in that the polycarboxylic acid is citric acid or citric acid with silicon dioxide. 8- Prefabricated element (1) for construction, according to any of claims 5 to 7, characterized in that the recycled aggregate (3) comprises a granulometry of: - maximum size of 10 mm, with a presence of between 1% and 8%; - size between 3-5 mm, with a presence of between 68% and 88%; - size between 0.2-0.05mm, with a presence of between 8% and 21%: - between 0.02-0.005mm, with a presence of between 1% and 6%. 9- Prefabricated element (1) for construction, according to any of claims 5 to 7, characterized in that the prefabricated aggregate (3) can be based on a single granulometry: - maximum size of 10 mm, with a presence of between 0% and 10%, - size between 3-5 mm, with a presence of between 0% and 100%; - size between 0.2-0.05mm, with a presence of between 0% and 100%; - size between 0.02-0.005mm, with a presence of between 1% and 10%; . and further comprises between 17.36% and 23.08% of water (4) of the weight of the prefabricated element (1) and between 0.01% and 0.2% of additive (5) of the weight of the prefabricated element (1), where the additive (5) is based on a polycarboxylic acid, a melamine compound and/or salts. 10- Prefabricated element (1) for construction, according to any of the preceding claims, characterized in that the aggregate (3) comprises a proportion of up to 30% of arlite or perlite, plus prefabricated aggregate (3). 11- Method for manufacturing a prefabricated element (1) for construction, according to any of the preceding claims, characterized in that it comprises the steps of: i) preparing an aggregate (3) based on calcium sulphate (31); ii) homogeneous mixing of a binder (2) of gypsum (21), of the aggregate (3) based on calcium sulphate (31) and of water (4); (ii) forming of the prefabricated element (1) by means of vibro compression. 12- Method of manufacturing a prefabricated element (1) for construction, according to claim 11, characterized in that it comprises the addition of a water additive (5) (4) based on a polycarboxylic acid. 13- Method of manufacturing a prefabricated element (1) for construction, according to any of claims 11 to 12, characterized in that the preparation of a mixture comprising an aggregate (3) based on calcium sulphate (31), water (4) and additive (5) and comprising a part of aggregates (3), recycled aggregates (3), quarry aggregates (3), arlite or perlite, and comprising the steps of: i.1) mixing the calcium sulphate (31) with water (4), additive (5) and aggregates (3); 1.2) kneading said mixture of calcium sulphate (31) with water (4), additive (5) and aggregates (3) in a horizontal rotary mixer (7) until obtaining grains (6) of calcium sulphate (31) of homogeneous size less than 8mm; 1.3) pouring the mixture into a vibro compression machine to obtain the prefabricated elements (1), 14- Method of manufacturing a prefabricated element (1) for construction, according to any of claims 11 to 13, characterized in that the preparation of an aggregate (3) based on calcium sulphate (31) comprises a prior stage of obtaining treated water (4) for mixing, where the treated water (4) comprises a setting retarder (9). 15- Method of manufacturing prefabricated aggregate (3), according to any of claims 11 to 14, characterized in that the preparation of an aggregate (3) based on calcium sulphate (31) comprises the steps of: .1) mixed calcium sulphate (31) with water (4) and additive (5); 1.2) pulverizing the mixture of calcium sulphate (31) with water (4) and additive (5) in a horizontal rotary mixer (7) until obtaining a grain (6) of calcium sulphate (31) of homogeneous size; 1.3) screening of calcium sulphate aggregate (31) with a diameter less than Bmm; 1.4) grinding of the grains (6) of calcium sulphate (31) with a diameter greater than 10mm in a fragmentation mill (8); 1.5) dehydration treatment of calcium sulphate (31). 16- Method of manufacturing prefabricated aggregate (3), according to claim 15, characterized in that the amount of water (4) is between 14.89% and 17.01% of the weight of the prefabricated element (1).