PREFABRICATED RECYCLED CONCRETE PAVEMENT

Abstract

Prefabricated recycled concrete pavement, formed from slabs consisting of each of a prefabricated piece (2) of vibro-compacted semi-dry concrete, is characterized by the fact that said pieces (2) have a composition where all the solid fractions used as aggregates and mineral fillers are 100% recycled materials, and by the fact that they have a configuration intended for placement on a flexible base (10) without the use of mortars or rigid slabs; where each piece (2) is formed by two integral layers obtained by sequential pouring and joint compaction consisting of: - a surface layer (3), of lesser thickness (e), where the concrete mixture that constitutes it incorporates solid fractions as aggregates and mineral fillers of recycled materials of lesser granulometry, defining the surface appearance; and - a base layer (4), of greater thickness (e') than the surface layer (3), wherein the concrete mixture that constitutes it incorporates solid fractions such as aggregates and mineral fillers of recycled materials with a larger particle size than in the surface layer (3), providing the load-bearing strength of the piece (2).

Description

PREFABRICATED RECYCLED CONCRETE PAVEMENT OBJECT OF THE INVENTION The invention relates, as stated in the present descriptive report, to a prefabricated recycled concrete pavement, which provides advantages and characteristics, which will be described in detail later and which represent an improvement on the current state of the art. More specifically, the object of the invention focuses on a concrete slab pavement, intended for exterior paving, where each slab is made up of a prefabricated piece obtained industrially by means of vibro-compaction technology of semi-dry concrete and controlled curing, with the particularity that it integrates, as essential aspects, the use in its composition of 100% recycled materials and a configuration specially made for its placement on a flexible base without the use of mortars or rigid slabs, also contemplating the incorporation of reinforced circular economy criteria in the complete cycle of the product, from the obtaining of secondary raw materials to its eventual dismantling and reuse on site. Specifically, the slab is a vibro-compacted semi-dry concrete piece, where all the solid fractions used as aggregates and mineral fillers are 100% recycled materials. It comprises a thinner surface layer incorporating recycled fractions and aggregates of smaller particle size and, optionally, recycled glass, and a thicker base layer incorporating larger recycled fractions, providing the load-bearing strength of the piece. Furthermore, the visible face of the surface layer preferably has a textured, anti-slip finish obtained through a dry abrasion process and, optionally, an additive that reduces open porosity and provides stain-resistant properties. SCOPE The field of application of the present invention falls within the field of construction, focusing particularly on the industry dedicated to the manufacture of prefabricated concrete for exterior paving. BACKGROUND OF THE INVENTION In the state of the art, precast concrete pavements, obtained by vibro-compaction in molds, are well known, offering multiple geometric and finishing possibilities. However, conventional solutions present significant limitations regarding the environmental impact of virgin raw material consumption, waste generation, and, in many cases, the product's design for placement on rigid systems. Furthermore, certain surface finishes can lose friction performance in the presence of water if the surface is excessively smooth or if the microtexture is not adequately controlled. In the field of the circular economy applied to construction, it is increasingly necessary to keep raw materials within production cycles for as long as possible, reducing waste and utilizing nearby recycled materials. Precast concrete plants have been working along these lines, from implementing mechanical crushing to valorize their own waste, with the aim of reincorporating material into the process and minimizing waste output, also extending this utilization to properly valorized waste from other industries. This strategy, applied comprehensively to the design of the pavement slab that is the subject of the invention and its intended use on a flexible base, allows for a technical proposal where the product not only incorporates recycled material, but also facilitates its recovery and reuse at the end of each use cycle. Furthermore, laying paving stones and slabs on a flexible base requires adherence to specific conditions to ensure the system is stable and durable. These conditions include preparing a properly compacted subbase and base, laying a geotextile where appropriate, using a granular bedding layer that accommodates tolerances and ensures uniform seating, filling and sealing joints with gravel (fine aggregate, generally with a particle size between 4-8 mm or 6-20 mm), and providing perimeter and, where necessary, partial lateral confinement to prevent displacement, joint opening, and loss of interlocking. These requirements make it advisable for the prefabricated element to be specifically designed to function within a flexible and reversible system. Similarly, the production of prefabricated pavements using 100% recycled materials guarantees compliance with all requirements and mechanical and durability performance standards. It also ensures the environmental compatibility of the materials and facilitates their accreditation in assessment and certification contexts. The objective of the present invention is, therefore, a pavement of slabs whose constitution and configuration fulfills these premises and needs. Furthermore, and with reference to the current state of the art, it should be noted that, although there are multiple types of pavements based on prefabricated concrete slabs on the market, at least as far as the applicant is concerned, there is no knowledge of any that presents technical, structural and constitutive characteristics equal or similar to those specifically presented by the one advocated herein, as claimed. EXPLANATION OF THE INVENTION The prefabricated recycled concrete pavement proposed by the invention is configured as an optimal solution to the aforementioned objective, with the characterizing details that distinguish it being conveniently included in the final claims that accompany this description. Specifically, the prefabricated recycled concrete pavement proposed by the present invention, as previously mentioned, is a pavement intended for exterior paving that is made up of pieces, each of which is a prefabricated piece of vibro-compacted semi-dry concrete, which has the particularity of having a composition where all the solid fractions used as aggregates and mineral fillers are 100% recycled materials and also has a configuration specially made for its placement on a flexible base without the use of mortars or rigid slabs. More specifically, these recycled materials are obtained through mechanical crushing and particle size classification of concrete and mineral elements, including, among others, internal manufacturing rejects that do not meet quality standards, concrete from demolition sites or other industries, crushed recycled glass, and industrial mineral waste suitable for recovery as aggregate or filler compatible with the cementitious matrix. These industrial mineral wastes may include, for example, foundry slag and sand. In all cases, the selection and conditioning of these fractions is carried out in such a way that they are suitable for a vibrocompaction process, guaranteeing the dimensional stability and mechanical resistance required of a prefabricated pavement. In an implementation aligned with the regional use of resources, the invention preferably utilizes recycled aggregates from internal streams (crushing of surplus materials, off-specification pieces, or site returns) and external streams from the construction and demolition sector, promoting circularity at a territorial scale. In environments with high annual generation of Construction and Demolition Waste (CDW) and recovery rates below European targets, the invention provides a stable industrial absorption pathway for these secondary materials. In any case, the slab is configured in two bonded layers obtained through sequential pouring and simultaneous compaction. The surface layer, where the visible face is located, is thinner and incorporates recycled fractions and aggregates of smaller particle sizes and, optionally, recycled glass, in order to optimize compactness and surface appearance. The thicker base layer incorporates larger recycled fractions, providing the load-bearing strength of the piece. This two-layer configuration allows the functional performance to be concentrated on the visible face with a limited consumption of resources, allocating the majority of the mass to a structural layer of recycled aggregates, thus maintaining the circularity objective. In applications using crushed recycled glass in the surface layer, the glass is sourced from nearby recycling plants with stable capacity, reinforcing traceability and supply availability. This approach is preferred in all cases, as recycled glass has been shown to improve thermal inertia and solar reflectance, adding environmental and aesthetic value to the pavement without compromising the required mechanical performance. In addition, the surface layer incorporates a textured surface finish, obtained through a dry abrasion process applied to the visible face once an adequate curing strength has been achieved. This dry abrasion process removes surface laitance and creates a stable micro- and macrotexture that increases friction and improves skid resistance, particularly in the presence of water. Unlike overly closed surfaces, the resulting texture promotes instant surface water runoff and reduces the film effect, improving safety when using the pavement in rain or when watering it. Additionally, and preferably, the mixture that makes up the surface layer of the slab includes an additive that reduces open porosity or modifies the surface wettability of the slab, providing a stain-repellent effect against dirt and stains. This stain-resistant effect facilitates cleaning and helps maintain the aesthetic appearance of the pavement, reducing maintenance needs and extending the product's lifespan, which aligns with the circular economy approach. In addition, the invention optionally contemplates the use of low-carbon cements, including types that reduce the clinker content, in order to decrease the carbon footprint associated with the binder without compromising mechanical and durability properties, through optimized dosages, experimental characterization and rheological design of the mixtures in vibrocompaction processes of semi-dry concrete. Furthermore, the pavement slab of the invention has also been designed for placement on a flexible base, without mortar, on a stratified system that typically comprises regularized and compacted natural ground, a compacted gravel base, the possible interposition of a permeable geotextile, a support bed of gravel or pebbles that absorbs tolerances and provides homogeneous seating, and the pavement formed by the slabs with joints filled and sealed with fine gravel. In addition, preferably, the existence of geometric means on the sides of the piece is considered to facilitate the regularity of the joint and its filling, specifically some lateral separators, allowing the assembly to work together on the granular bed. The system's stability is further enhanced by the perimeter lateral confinement of the pavement and, where the surface area is large, by partial confinement measures designed to limit movement of the slab assembly. The dry-laying design on a flexible base integrates advantageously with the trend towards industrialized, sustainable, and reversible construction systems, facilitating rapid execution, immediate commissioning, and access to services through lifting and repositioning, thus reducing waste and extending the pavement's service life. The following details an example of the process of obtaining the concrete slab that constitutes the prefabricated pavement of the invention, which, as noted, is obtained from a semi-dry mixture of cement, water and 100% recycled solid fractions. Recycled aggregates are prepared by mechanically crushing and screening concrete and mineral materials, separating particle sizes for different uses. A fine fraction is used for the surface layer, and larger fractions are used for the base layer. Optionally, crushed recycled glass is incorporated, especially in the surface layer, as well as recovered industrial mineral fractions when they are compatible with the cementitious matrix. The preparation process ensures the removal of impurities and the obtaining of appropriate granulometries. The slab is manufactured using a vibro-compaction press. The base layer, composed of thicker solid fractions, is placed in the mold first. Next, the top layer, a thinner layer, is added, incorporating a stain-resistant additive when required. The assembly is then subjected to vibro-compaction and pressing until a monolithic piece is obtained, in which both layers are rigidly bonded. After demolding, the piece is cured under controlled conditions until it reaches sufficient strength for handling and subsequent finishing. Once the piece has reached the appropriate strength, the exposed face undergoes a dry abrasion process. This process is carried out using mechanically driven abrasive elements (e.g., discs, brushes, or belts), adjusting pressure, speed, and number of passes to achieve a homogeneous texture. The abrasion removes the surface layer of grout and partially exposes the fine recycled aggregate, generating a stable micro- and macro-texture that increases friction in dry conditions and, significantly, in wet conditions. As previously mentioned, the slab is designed for placement on a flexible base. In a typical application, the natural ground is leveled and compacted, a compacted subbase is laid, and a permeable geotextile is installed where appropriate. A bedding layer of gravel or pebbles is then spread over the geotextile or the subbase. This layer accommodates manufacturing tolerances and ensures uniform settling after installation. The slabs are placed on this bed, leaving a regular joint between them, and then settled using a vibrating plate compactor. The surface is then covered with fine gravel, preferably 2-4 mm in size, repeating the covering and light compaction process until the joints are filled. Finally, the surface is swept in several directions until completely filled.The provision of a perimeter confinement prior to the commissioning of the pavement is planned and, in large areas, partial confinements distributed at indicative intervals to improve the stability of the whole. The flexible base design offers significant technical advantages, as it allows for immediate commissioning, repairs or access to infrastructure are resolved by lifting and repositioning pieces, and the pavement is reusable, contributing to extending the product's life cycle and reducing waste. By combining this approach with the use of 100% recycled materials and the possibility of reintroducing manufacturing rejects into the process through shredding, the pavement slab of the invention effectively reinforces the principles of a circular economy. The object of the invention is therefore to provide an ecological, 100% recycled, prefabricated concrete pavement for exteriors, manufactured from, among other things, recycled materials and waste from other industries, which has a high anti-slip capacity and is specially designed for placement without mortar. The pavement of the invention is suitable for immediate industrial application using standard prefabrication procedures involving vibro-compaction and curing, and mechanical finishing operations. Its production is scalable and compatible with industrial prefabrication lines. Key advantages include reduced consumption of natural resources through the use of 100% recycled materials, a significant reduction in carbon footprint, decreased waste through internal recirculation of recovered material, improved user safety due to the texture obtained through dry abrasion, particularly in wet conditions, improved maintenance through reduced surface porosity using stain-resistant additives, and the possibility of dismantling and reusing the pavement thanks to its design for installation on a flexible base. Additionally, the invention is suitable for advanced waste management systems, allowing the pavement manufacturer to collect, sort, and process materials at its facilities as an authorized waste manager, acting as a regional hub for the recovery of inert waste, in coordination with waste management companies and crushing plants. This approach strengthens the traceability and stability of the supply of secondary raw materials and improves the closure of the material cycle. Finally, it should be noted that the pavement subject to the invention is especially applicable for the execution of modular pavements and surfaces in urban environments such as sidewalks, squares, parks, promenades, pedestrian areas, commercial areas and traffic roads, with special interest in those locations where it is crucial to combine sustainability, speed of execution and reversibility of the construction system. Furthermore, its manufacture and / or installation is particularly relevant in areas where there is a local availability of recoverable mineral waste, as it allows for the utilization of nearby and stable secondary resources. This is especially true in regional contexts with high levels of construction and demolition waste, since the use of recycled aggregates contributes to improved recovery rates and reduces dependence on natural aggregates. DESCRIPTION OF THE DRAWINGS To complement the description being made and in order to help a better understanding of the characteristics of the invention, this descriptive report is accompanied, as an integral part thereof, by a set of drawings, in which the following has been represented for illustrative and non-limiting purposes: Figure 1 shows a schematic perspective view of an example of one of the slabs that make up the prefabricated recycled concrete pavement of the invention, showing the configuration of the layers it comprises. And figure number 2.- Shows a schematic sectioned perspective view of an example of pavement placement on a flexible base, showing the different layers of the same. PREFERRED EMBODIMENT OF THE INVENTION In view of the aforementioned figures and in accordance with the numbering adopted, one can observe in them a non-limiting example of the embodiment of the prefabricated recycled concrete pavement of the invention, which comprises the parts indicated and described in detail below. Thus, as can be seen in said figures, the pavement (1) of the invention, made up of slabs consisting, each, of a prefabricated piece (2) of vibro-compacted semi-dry concrete, is distinguished essentially by the fact that said pieces (2) have a composition where all the solid fractions used as aggregates and mineral fillers are 100% recycled materials, and by the fact that they have a configuration intended for placement on a flexible base (10) without the use of mortars or rigid slabs. To this end, as shown in Figure 1, the prefabricated concrete piece (2) that constitutes each of the pavement slabs (1) is formed by two integral layers obtained by sequential pouring and joint compaction consisting of: - a surface layer (3), of lesser thickness (e), where the concrete mixture that constitutes it incorporates solid fractions such as aggregates and mineral fillers of recycled materials of smaller granulometry, defining the surface appearance; and - a base layer (4), of greater thickness (e) than the surface layer (3), where the concrete mixture that constitutes it incorporates solid fractions such as aggregates and mineral fillers of recycled materials of greater granulometry than in the surface layer (3), providing the load-bearing resistance of the piece (2). Preferably, the surface layer (3) has, on its visible face (3a), an anti-slip surface finish, obtained through a dry abrasion process, which removes the surface layer of grout and partially exposes the fine recycled aggregate, generating a micro and macro texture. Preferably, the concrete mix that constitutes the surface layer (3) of the prefabricated concrete piece (2) includes an anti-stain additive, which reduces open porosity, modifies surface wettability, and has a repellent effect against dirt and stains. Optionally, the concrete mixture that constitutes the surface layer (3) of the prefabricated concrete piece (2) incorporates, as aggregates and mineral fillers of recycled materials, a recycled glass fraction. In addition, preferably, the piece (2) that makes up each pavement slab (1) has side spacers (5) that facilitate the regularity of the joint (11) and its filling in the formation of the pavement. In a preferred embodiment of the invention, the surface layer (3) of the piece (2) comprises a semi-dry mixture including cement, which may be white or gray, in a proportion of between 15% and 25% of the total weight of the mixture, fine recycled aggregate based on crushed and classified recycled concrete, with a particle size between 2 mm and 4 mm in a proportion between 60% and 80%, recycled glass with a particle size of 0.1 mm to 2 mm in a proportion between 0% and 5%, and a stain-repellent anti-additive compatible with the cementitious matrix between 0.1% and 2%, and wherein the maximum thickness (e) of the surface layer is equal to or less than 15 mm. More preferably, the surface layer (3) comprises low carbon grey cement, in a proportion of 20% of the total dry mix weight, fine recycled aggregate in a proportion of 76% of the total, recycled glass in a proportion of 3% of the total, and anti-stain additive in a proportion of 1% of the total dry mix. In the preferred embodiment, the base layer (4) comprises a semi-dry mix that includes cement, which may be white or gray, in a proportion of between 15% and 25% of the total weight of the dry mix, coarse recycled aggregate based on crushed and classified recycled concrete, with a particle size between 5 mm and 12 mm in a proportion between 55% and 70%, fine recycled aggregate based on crushed and classified recycled concrete, with a particle size between 2 mm and 4 mm in a proportion between 5% and 10%, and foundry sands with a particle size between 0 mm and 3 mm in a proportion between 10% and 20%, and in which the thickness (e) may be between 30 mm and 150 mm. And, more preferably, the base layer (4) comprises a semi-dry mix that includes low carbon gray cement in a proportion of 20% of the total dry mix weight, coarse recycled aggregate based on crushed and classified recycled concrete, in a proportion of 60% of the total weight, fine recycled aggregate based on crushed and classified recycled concrete, in a proportion of 5% of the total weight, and foundry sands in a proportion of 15% of the total dry mix weight. Furthermore, according to Figure 2, it can be seen how the pavement (1) of the invention is specially designed for incorporation into a flexible base (10) without the use of mortars or rigid slabs, said base being of the type formed by a stratified system comprising, regularized and compacted natural ground (6), a compacted gravel base (7), optionally including the interposition of a permeable geotextile (not shown), a support bed (8) of gravel or pebbles that absorbs tolerances and provides homogeneous seating, placing on said system the pavement (1) formed by the pieces (2) that constitute the slabs with joints (11) filled and capped by means of fine gravel. Furthermore, the stability of the system is completed by the inclusion of a lateral confinement edge (9) of the pavement (1) intended to limit movements of the assembly of pieces (2), which can be completely perimeter or, when the surface is large, cover only partial portions. Having sufficiently described the nature of the present invention, as well as the manner of putting it into practice, it is not considered necessary to make its explanation more extensive so that any expert in the field can understand its scope and the advantages that derive from it.

Claims

1. Prefabricated recycled concrete pavement, formed from slabs consisting of each of a prefabricated vibro-compacted semi-dry concrete piece (2), characterized in that said pieces (2) have a composition where all the solid fractions used as aggregates and mineral fillers are 100% recycled materials, and in that they have a configuration intended for placement on a flexible base (10) without the use of mortars or rigid screeds; where each piece (2) is formed by two integral layers obtained by sequential pouring and joint compaction consisting of: - a surface layer (3), of lesser thickness (e), where the concrete mix that constitutes it incorporates solid fractions as aggregates and mineral fillers of recycled materials of smaller granulometry, defining the surface appearance; and - a base layer (4), of greater thickness (e') than the surface layer (3),where the concrete mix that constitutes it incorporates solid fractions such as aggregates and mineral fillers of recycled materials with a larger particle size than in the surface layer (3), providing the load-bearing strength of the piece (2).

2. Precast recycled concrete pavement, according to claim 1, characterized in that the surface layer (3) has, on its visible face (3a), an anti-slip surface finish, obtained by a dry abrasion process, which generates a micro and macro texture.

3. Precast recycled concrete pavement, according to claim 1 or 2, characterized in that the concrete mix that constitutes the surface layer (3) of the precast concrete piece (2) includes an anti-stain additive.

4. Precast recycled concrete pavement, according to any of claims 1 to 3, characterized in that the concrete mix that constitutes the surface layer (3) of the precast concrete piece (2) incorporates,such as aggregates and mineral fillers of recycled materials, recycled glass fraction.

5. Precast recycled concrete pavement, according to any of the preceding claims, characterized in that the piece (2) that makes up each pavement slab (1) has lateral spacers (5) that facilitate joint regularity (6) and its filling during pavement formation.

6. Precast recycled concrete pavement, according to claim 1, characterized in that the surface layer (3) of the piece (2) comprises a semi-dry mix including white or gray cement in a proportion of between 15% and 25% of the total weight of the mix, fine recycled aggregate based on crushed and classified recycled concrete, with a particle size between 2 mm and 4 mm in a proportion between 60% and 80%, recycled glass with a particle size of 0.1 mm to 2 mm in a proportion between 0% and 5%, and an anti-stain additive compatible with the cementitious matrix between 0.1% and 2%, and wherein the maximum thickness (e) of said surface layer (3) is equal to or less than 15 mm.

7. Precast recycled concrete pavement, according to claim 6, characterized in that the surface layer (3) comprises low-carbon gray cement, in a proportion of 20% of the total dry mix weight, fine recycled aggregate in a proportion of 76% of the total, recycled glass in a proportion of 3% of the total, and anti-stain additive in a proportion of 1% of the total dry mix.

8. Precast recycled concrete pavement, according to claim 1, characterized in that the base layer (4) comprises a semi-dry mix including white or gray cement in a proportion of between 15% and 25% of the total dry mix weight, coarse recycled aggregate based on crushed and classified recycled concrete, with a particle size between 5 mm and 12 mm in a proportion of between 55% and 70%,Recycled concrete pavement, according to claim 8, characterized in that the base layer (4) comprises a semi-dry mix comprising a low-carbon gray cement in a proportion of 20% of the total dry mix weight, coarse recycled aggregate based on crushed and classified recycled concrete, in a proportion of 60% of the total weight, fine recycled aggregate based on crushed and classified recycled concrete, in a proportion of 5% of the total weight, and foundry sands in a proportion of 15% of the total dry mix weight. The base layer (4) comprises fine recycled aggregate based on crushed and classified recycled concrete, in a proportion of 5% of the total weight, and foundry sands in a proportion of 15% of the total dry mix weight.