Bioactive marine concrete and uses thereof

Abstract

The present disclosure relates to the use of a bioactive marine concrete as a marine structure, or as an artificial reef structure to restore and protect marine ecosystem, wherein the bioactive marine concrete comprises: a concrete comprising at least 50% of conductive materials including aggregates, fibers; fine additions; an electric circuit; and a mineral layer on the surface of the concrete. It is also disclosed a method of obtaining the bioactive layer on marine concrete structure and the method for producing the bioactive marine concrete.

Description

D E S C R I P T I O NBIOACTIVE MARINE CONCRETE AND USES THEREOFTECH NICAL FIELD

[0001] The present disclosure relates to a bioactive marine concrete, as well as the method of obtaining the bioactive marine concrete. Specifically, the present disclosure relates to sustainable electrically conductive concrete and the method of obtaining the bioactive marine concrete using electrodeposition of minerals naturally found in seawater to create a natural layer similar to the one found in coral reefs.BACKGROUND

[0002] Biomimetics is the scientific field that aims to study biological structures and their functions, seeking to learn strategies and solutions from nature, and use this knowledge in different scientific domain. Lower marine organisms use the mineral solutions around them to build structural formations such as Molluscan shells that are mainly made up of calcium carbonate crystals enclosed in an organic matrix [1, 2], Another example is coral reefs, which are natural builders of calcium carbonate structures due to the symbiosis with some algae called zooxanthellae which helps in the growth of coral skeletons. In nature, all organisms contributed to balance the environment, each having a specific and special function. The main focus is on the symbiosis and synergy created by different organisms to improve their quality of life, including protection, food, shelter, etc. Mimic this mutual contribution rather than the exhaustive exploitation of the environment is an important fact to keep in mind today. The main cause of environmental destruction is human activity that, in most cases, does not consider environmental needs in its designs and solutions, exploiting, unbalancing, and affecting all organisms on earth, including all of us. Future materials, especially building materials, must be designed to integrate and contribute to regeneration and maintenance of the environment balance.

[0003] Since Michael Faraday, in the early 1900s, discovered the electrolysis of water, a number of studies have been done on the process [1-6], In 1981 and 1984, Wolf H. Hilbertz reported the feasibility of using electrodeposited minerals as a building material and also to repair fractured reinforced concrete structures by mineral accretion, respectively [1, 2], The contribution of all thestudies around the electrolysis process and its application has been quite important for the restoration of marine ecosystems, mainly coral reefs that have been drastically affected essentially due to global warming, overfishing and pollution. Corals cover only 1% of the ocean floor, but support 25% of marine life, and are shown to play a large role in the oceans balance. In particular, steel structures have been used to reproduce the electrolysis process and create a biogenic surface promoting biofouling, and hence restoration of the marine ecosystem [1-6], Currently, humans are overwhelming Ocean with alien structures, most of them to exploit essential resources to modern life, and also others as an attempt to mitigate environmental and biological problems caused by intensive exploitation activities, as mentioned before.

[0004] However, attempts to create multifunctional structures that simultaneously cover all current and future human activities and the balance of marine life and its vitality, failed. The art is absent in teaching the creation of a bioactive layer over concrete to promote biofouling and the protection of concrete marine structures over time through electrodeposition of minerals naturally found in seawater. Concrete has been widely used as a structural material due to its great structural properties to build complex structures and the ability to adapt to different environments. However, conventional concrete has a very high electrical resistivity (approximately 107Q.m) [ [7-15], a value that is insufficient to promote electrolysis, and consequently mineral accretion [1-6], Hilbertz only reported the repair of reinforced concrete structures by mineral accretion in his patent in 1984 because only fractured conventional concrete is capable of inducing the reaction due to exposing the steel bars, that function as a cathode in the electric circuit [2], If the concrete is not fractured with cracks, fissures or voids, electrodeposition would not be possible due to the very low conductivity of the conventional concrete. Fissures, cracks, or voids allow an electric field to be created between an anode and a steel bar that is inside conventional concrete (cathode), where the repair of the structure is processed. However, the invention does not use the active principle of the electrolysis process to protect and create a natural layer on the concrete, due to the lack of electrical conductivity of conventional concrete.

[0005] Seawater contains a large number of known chemical components, showing a huge network of dissolved materials. The major components are often described as nine, such as bromine, chlorine, carbon, calcium, magnesium, potassium, strontium, sodium, and sulfur; and consist of more than 99.9% of all dissolved salts in ocean water. Due to the high salinity ofseawater and through diagenesis (electrolytic process) and sequential biogenesis (biological phasing), unstructured materials are precipitated into electrically conductive concrete and probably chemicals transformed by biological organisms into materials with structural capabilities. Using biomimetics it may be possible to reproduce natural surfaces, suitable for the environment and the concrete structure itself. Electrolytic processes can be used specifically to electrodeposit minerals onto suitable surfaces. A given electrical potential between electrodes will deposit positive ions at the cathode and negative ions at the anode. During the electrolytic process, the main materials precipitated are magnesium hydroxide and calcium carbonate which have a compressive strength similar to that of conventional concrete, ideal for protecting the main structure from damage. In addition, calcium carbonate is the main component of coral reefs, shells, mollusks and other marine living organisms, which seems to be a good layer to create a natural synergy between the structure and the marine environment, as mentioned by other authors. Additionally, the creation of this natural layer with good mechanical properties depends on some variables such as temperature and the presence of living marine organisms.

[0006] The principle of the electrolytic process is only possible if between electrodes submerged in seawater there is an electric field caused by the imposed direct electric current, forcing the electrodes to be very conductive, like metals [1-6], In the present invention, the concrete itself is highly electrically conductive enhancing its application in the marine environment with greater environmental integration. These innovative, bioactive marine concrete, unlike conventional marine concretes, may not have biological problems or structural problems related to living organisms due to their unique characteristics. Marine and offshore structures currently face serious problems of premature degradation due to remote locations, corrosive environment, varying mechanical action to which these structures are subjected, and biological fouling, and often resort to toxic substances to retard deterioration and biofouling. These problems are converted into other problems, such as higher costs of repair operations, the use of more materials, the generation of waste and the destruction of marine fauna and, consequently, social, environmental and economic impacts.

[0007] The term "biorock" was patented by Wolf H. Hilbertz and refers to a cement-like engineering material formed when a small electrical current is passed between underwater metal electrodes placed in seawater causing dissolved minerals to accrete onto the cathode to form a thick layer of limestone [1], This 'accretion process' can be used to create building materials or tocreate artificial 'electrified reefs' for the benefit of corals and other sea-life.

[0008] The term "bioactive marine concrete" refers to high electrical conductivity concrete that is capable of inducing the precipitation of minerals naturally found in seawater by imposing an electrolytic process, without being damaged.

[0009] These facts are disclosed to illustrate the technical problem addressed by the present disclosure.GENERAL DESCRIPTION

[0010] The present disclosure relates to a bioactive marine concrete, as well as the method of obtaining the bioactive marine concrete.

[0011] A marine concrete is also known as offshore concrete or underwater concrete. Particularly is a type of concrete used in construction projects that are exposed to harsh marine environments. This type of concrete can be used in bridges, ports, harbors, offshore oil and gas platforms, coastal protection structures, underwater tunnels and artificial reefs. It is important that these structures withstand the damage effects especially related to biofouling that is very common in this type of structures.

[0012] An aspect of the present disclosure relates to a bioactive marine concrete composition comprising waste materials, more particularly, aggregates and fibers. The production of the bioactive concrete composition of the present disclosure contributes to sustainability by promoting the reuse of residues.

[0013] In an embodiment, the bioactive marine concrete composition of the present disclosure exhibits high electrical conductivity, never reported before in the literature.

[0014] In an embodiment, the bioactive concrete has the advantage that its high electrical conductivity allows current to flow through the concrete and creates a natural bioactive material over the concrete surface.

[0015] In an embodiment, the bioactive marine concrete is capable of inducing mineral accretion without the need to be fractured and hence the mechanical properties of the structure are not compromised. The bioactive marine concrete of the present disclosure undergoes mineral accretion without fracturing, but instead becomes stronger as electrolysis continues to take place.

[0016] In an embodiment, the bioactive marine concrete of the present disclosure is a highly electrically conductive that is obtained through electrodeposition of minerals onto the surface of concrete.

[0017] As utilized herein, "highly electrically conductive concrete structure" refers to a structure comprising a solid mass formed by concretion or coalescence of separate particles of matter in one body and having electrically conductive ingredients such as fibers and aggregates; and / or fine additions embedded within it, all components work together to resist forces and create a high level of electrical conductivity to facilitate the accretion of the bioactive layer.

[0018] In an embodiment, the solid mass portion of the structure is made by Portland cement or another binder to set and bind the entire mass, waste materials such as fly ash, electrically conductive powder (fine additions) and aggregates, micro electrically conductive fibers especially carbon fibers (recycled or not), tap water or seawater, and additives like superplasticizer, plasticizer or viscosity modifying agent. The reinforcing materials that help to improve the electrical conductivity of the material are fibers, aggregates and other fine additions.

[0019] Another aspect of the present disclosure relates to a method of obtaining a bioactive surface on a concrete structure surface, comprising the step of putting the conductive concrete in a volume of electrolyte, preferably seawater (artificial or natural). The conductive concrete is connected to a negative potential terminal of a direct current electrical power supply, behaving as a cathode. An anode is placed in the electrolyte in the vicinity to the conductive concrete structure and is connected to the positive terminal of the direct current electrical power supply. An electric field is formed by positive and negative charges for a time sufficient for accreting a solid mass of high strength electrodeposited mineral material over the concrete surface, thus forming a bioactive and bioprotective layer over the concrete surface.

[0020] The method of the present disclosure has the advantage that the formation of the bioactive layer over the concrete surface occurs in situ, promoting structure protection and natural synergy with the marine environment hence imitating a natural process.

[0021] In an embodiment, the electrically conductive material may be conductive waste, preferably conductive fibers, conductive aggregates and fine additions such as electric arc furnace slag (EAFS) with different granulometry, and / or recycled conductive fibers and / or powder.

[0022] In an embodiment, the addition to the concrete of the present disclosure of conductivefiber and / or conductive aggregate improves the electrical properties of the concrete and consequently could enhance its durability, resistance to chemical attacks, and overall performance under adverse environmental conditions. This enhanced durability ensures a longer service life for infrastructure, leading to lower replacement and maintenance costs.

[0023] In an embodiment, the bioactive marine concrete comprises a concrete mixture containing a minimum of 50% (w / w) conductive materials, including aggregates and fibers. The fine additions can also be conductive and are selected from fly ashes, electric arc furnace slag (EAFS) powder, recycled or not carbon powder and / or graphite, or other conductive residues. The bioactive layer is formed through a process of mineral accretion, which is achieved by applying direct electric current to the concrete, inducing electrodeposition and facilitating the formation of a natural mineral layer.

[0024] An aggregate, in the context of construction and civil engineering, refers to a granular material that is used as a fundamental component in concrete, mortar, asphalt, and other construction mixes. Aggregates typically consist of particles such as sand, gravel, crushed stone, slag, recycled concrete, or other inert materials with various particle sizes.

[0025] Electrically conductive aggregates play a crucial role in the present disclosure due to their ability to enhance the properties of the final product. The used aggregates have at least 30 % (w / w) of the conductive material in its composition and are considered waste materials.

[0026] Electrically conductive aggregates consist of particles with a continuous grading, typically with a particle size of less than 50 mm. Metal particles are the most common type of electrically conductive material found in these aggregates. The measurement of the aggregates may be carried out in various ways and in this disclosure the measurement of the granulometry / particle size was carried out on the basis of the standard forgranulometric analysis by mechanical sieving, namely the one described by BS EN 933-11:2009.

[0027] Electrically conductive fibers consist of recycled and / or industrial fibers, usually with a major size of less than 10 mm and a thickness of 2 mm. Carbon and metal fibers are the most common types of electrically conductive fiber.

[0028] In an embodiment, the concrete material of the present disclosure may be used:• to restore marine ecosystems like artificial reefs and promote other types of activities;• as offshore structures and marine structures as a strategy to mitigate degradationproblems and the use of toxic substances to delay degradation problems, as well as biological incrustation in conventional marine structures;• as complex and resistant marine structures especially made to protect the coast from sea level rise, also functioning as a living barrier similar to coral reefs with several economic, social and environment applications and benefits.• To support the implementation of ocean or geological measurement and monitoring systems, or even to produce clean energy.

[0029] In an embodiment, the method of obtaining a bioactive surface over a non-fractured conductive concrete body with an electrically conductive cable embedded therein comprises the steps of (Figure 2):• Placing a fractured or a non-fractured conductive concrete structure in a volume of electrolyte;• Placing an anode in the vicinity of the conductive concrete structure;• Connecting the concrete structure to the negative potential terminal of an electrical power supply;• Connecting the anode to the positive potential terminal of the electrical power supply;• Settling a direct current between electrodes (cathode and anode) for a sufficient time to precipitate a solid mass of high strength electrodeposited mineral material over the concrete surface to cover all the surface thus forming a bioactive surface.

[0030] In an embodiment, the concrete is subjected to direct electric current for at least 1 day.

[0031] In an embodiment, the voltage ranges from 1 volt to 100 volts per square meter area of cathodic material.

[0032] In an embodiment, the electrical current ranges from 1 milli-amperes to 20 amperes per square meter area of cathodic material.

[0033] In an embodiment, the electrolyte is a mineral-containing liquid, preferably natural or artificial seawater.

[0034] It is disclosed the use of a bioactive marine concrete as a marine structure, or as an artificial reef and coral, wherein the bioactive marine concrete comprises: a concrete comprisingat least 50% of conductive materials including aggregates and fibers; an electric circuit; and a mineral layer on the surface of the concrete.

[0035] In an embodiment, the bioactive marine concrete comprises: a concrete comprising cementitious material, fine additions; water, additives; at least 50% (w / w) of conductive materials including aggregates and fibers; an electric circuit; and a mineral layer on the surface of the concrete.

[0036] The bioactive marine concrete of the present disclosure aims to improve the durability and lifespan of concrete structures by allowing them to create a natural bioactive layer that protects the structure from damage and promotes healthy biofouling.

[0037] In an embodiment, the amount of water is at least 5% (w / w) and the amount of additive is at least 0.10% (w / w).

[0038] In an embodiment, the fine additions may be in the form of filler or powder.

[0039] In an embodiment, the fine addition is electrically conductive.

[0040] In an embodiment, the fine addition is not electrically conductive.

[0041] In an embodiment, an amount of the fine addition is electrically conductive and another amount of the fine addition is not electrically conductive.

[0042] In an embodiment, the bioactive marine concrete has an electrical resistivity equal or lower than 0.3 Q.m, preferably between l.OxlO-7Q.m and 0.3 Q.m. A voltage is induced across each specimen using a power supply, and the electrical current is then measured. Based on the geometry of the electrodes, the dimensions of the specimen, and the obtained electrical current, the electrical resistivity is calculated.

[0043] "Bioactive marine concrete structures" refer to structures that consist of a solid mass formed by the concretion or coalescence of individual particles of matter into a single body. These structures incorporate electrically conductive ingredients, including fibers and aggregates and / or conductive fine additions, which are embedded within the concrete. This combination of components works collectively to resist external forces and create a high level of electrical conductivity, enabling the structure to create a bioactive layer itself under specific conditions.

[0044] In an embodiment, the solid mass portion of the structure is made by cement Portland or another binder to set and bind the entire mass, waste materials such as fly ash, electricallyconductive powder and aggregates, micro electrically conductive fibers especially carbon fibers (recycled or not), tap water or seawater (artificial or not), and additives like superplasticizer, plasticizer or viscosity modifying agent. The reinforcing materials that help to improve the electrical conductivity of the material are fibers, aggregates and other conductive fine additions such as EAFS powder, recycled or not carbon powder and / or graphite.

[0045] In an embodiment, the electric circuit is composed of an electric power supply with direct current, a highly electrically conductive concrete functioning as a cathode that could be connected to a conductive wire, and an electrode functioning as an anode.

[0046] In an embodiment, the electric circuit is a direct current electric circuit.

[0047] It is also disclosed a marine structure, or an artificial reef and coral comprising concrete containing at least 50% of electrically conductive material; wherein the electrically conductive material is in the form of aggregates and fibers; fine additions; water, and additives.

[0048] Marine structure, or an artificial reef and coral according to the previous claim wherein the amount of electrically conductive aggregates is from 50% (w / w) to 70% (w / w), preferably 62 %-65% (w / w).

[0049] In an embodiment, the conductive aggregate is made of steel, iron, copper, aluminium, carbon, graphite or combinations thereof, preferably residues.

[0050] In an embodiment, the micro electrically conductive fibers are made of carbon, steel or any other conductive material, including electrically conductive recycled fibers.

[0051] In an embodiment, the electrically conductive aggregate comprises a density ranging between 1800 kg / m3and 3580 kg / m3. The density was determined according to the standard EN 1097-6:2022.

[0052] In an embodiment, the conductive aggregate size ranges from 0-50 mm, preferably between 0 and 4mm. Measurement of the conductive aggregate size can be carried out in a number of ways, namely Microscopy; Laser Diffraction; Dynamic Light Scattering (DLS); Sedimentation; Electron Microscopy: Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM); X-ray Diffraction (XRD), X-Ray fluorescence (XRF), among other. In this disclosure the conductive aggregate size was measured by X-Ray Fluorescence (XRF).

[0053] In an embodiment further comprising electrically conductive fibers including recycled fibers, preferably carbon fiber.

[0054] In an embodiment, the density of conductive fibers ranging between 1800 kg / m3and 7850 kg / m3.

[0055] In an embodiment, the additives are selected from a list consisting of superplasticizer, plasticizer, and viscosity modifying agent, or combinations thereof.

[0056] It is also disclosed a method of obtaining the bioactive marine concrete comprising the steps of: immersing a fractured or a non-fractured concrete in a solution of electrolyte; connecting the concrete to a direct current electric circuit; subjecting the concrete to direct electric current to form a bioactive concrete and allow mineral accretion to form a mineral layer on the concrete surface.

[0057] In an embodiment, the solution of electrolyte is artificial seawater or natural seawater.

[0058] In an embodiment, the concrete is subjected to direct electric current for at least 1 day.

[0059] In an embodiment, the voltage is between 1 volt and 100 volts, and an electrical current between 1 milli-amperes and 20 amperes.

[0060] In an embodiment, electrolyte has a salinity concentration of between 30%o e 35%o.

[0061] In an embodiment, the electrolyte has a salinity equal to the salinity of seawater.

[0062] In an embodiment, the electric circuit comprises an electric power supply with direct current, a highly electrically conductive concrete functioning as a cathode, and an electrode functioning as an anode.

[0063] In an embodiment, the electric circuit is a direct current electric circuit.

[0064] It is also disclosed a method for producing bioactive marine concrete, comprising the steps of: mixing concrete matrix comprising cementitious material, water and additives to form a concrete mixture; incorporating at least 50% (w / w) of electrically conductive material; wherein the electrically conductive material is in the form of aggregate and fibers into said concrete mixture to produce a bioactive concrete; incorporate the fine additions.

[0065] In an embodiment, at least 0.1% of the electrically conductive material is electrically conductive fibers including carbon fibers, preferably recycled fibers.

[0066] In an embodiment, the amount of the fine additions is at least 5% (w / w), preferably from 15%-20% (w / w).

[0067] In an embodiment, the electrically conductive fibers are made of carbon, steel or any other conductive material, including electrically conductive recycled fibers.

[0068] In an embodiment, the fine additions are selected from a list comprising: fly ashes, electric arc furnace slag powder, carbon powder, graphite or mixtures thereof.

[0069] In an embodiment, the water is tap water or seawater.

[0070] In an embodiment, the solution of electrolyte is artificial seawater or natural seawater.

[0071] The method described offers the advantage of creating a natural bioactive layer as providing structural protection and establishing a natural synergy with the marine environment, mimicking a natural process.BRI EF DESCRIPTION OF TH E DRAWINGS

[0072] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

[0073] Figure 1 shows a theoretical qualitative model for electrochemical processes involved in the accretion of minerals.

[0074] Figure 2 is a schematic diagram of an arrangement for mineral accretion following the present invention of a highly electrically conductive concrete submerged in seawater.

[0075] Figure 3 shows precipitation of minerals like calcium carbonate and magnesium hydroxide on concrete through natural seawater electrolysis - 3 days.

[0076] Figure 4 shows precipitation of minerals like calcium carbonate and magnesium hydroxide on concrete through artificial seawater electrolysis - 1 month.DETAILED DESCRIPTION

[0077] The present disclosure relates to a bioactive marine concrete, as well as the method for obtaining the bioactive marine concrete.

[0078] The bioactive marine concrete of the present disclosure is a sustainable material obtained by mineral accumulation. The bioactive marine concrete of the present disclosure can contribute to the protection and balance of the environment, while mitigating the serious problems that marine structures may face throughout their life cycle. The construction of marine structures contributes to many human activities, from which numerous benefits are derived for social and economic needs. However, the conventional approach taken so far has severely affected the marine environment, including the living organisms on which societies depend, and a new and synergistic approach must be applied to address the future relationship between these two complex systems.

[0079] In this sense, this highly electrically conductive concrete can become in the near future an important part of the promising innovative marine systems that show bioactive surfaces as an ally to withstand the harsh exposure conditions of the environment.

[0080] In an embodiment, electrodeposition of mineral materials to obtain a bioactive surface concrete is performed.

[0081] In an embodiment, an evaluation of the mineral accretion process was performed using a direct current (DC) power supply using a voltage range of 10 volts. The positive source was connected to platinum-coated cylindrical titanium which functioned as the anode and the negative source was connected to a cable switch inside the concrete, which functioned as the cathode. The cable was added to ensure the electrical potential between all points in the concrete sample. Consequently, the current flowed through the concrete, as shown in Figure 2.

[0082] In an embodiment, the evaluation of the electrical mineral accumulation process was carried out for three days and for one month under laboratory conditions. A plastic container with natural seawater was used to perform the experiments. The concrete sample and platinum- coated titanium were placed inside a plastic box, connected to a DC power supply, acting as cathode and anode, respectively. Two different experiments were performed. One of them with natural seawater (Figure 3) and the other with artificial seawater (Figure 4). The process of electric mineral accumulation at the cathode was evaluated at the end of the experiment, mainlythrough photographs.

[0083] In the first experiment, the mineral precipitation was quite fast, showing a large accumulation of mineral rock only after three days, as shown in Figure 3. As shown in these figures, a white, gelatinous mineral material was precipitated on the cathode. From the X-ray diffraction test it was possible to identify the presence of mainly magnesium hydroxide, which proves the efficiency of the present invention in reproducing a bioactive layer, as has been proven by other authors in other types of structures, mainly steel.

[0084] In the second experiment (with artificial seawater) it was possible to observe a more consistent and denser mineral layer covering entirely almost all surfaces after 1 month (Figure 4).

[0085] Figure 1 shows a theoretical qualitative model for electrochemical processes involved in the accretion of minerals. The present figure describes the chemical reactions provoked by the electrolytic process and how it formed the electrodeposited mineral materials like magnesium hydroxide chemically called Mg (OH)? and calcium carbonate chemically named CaCOs, on the cathode.

[0086] Figure 2 is a schematic diagram of an arrangement for mineral accretion following the present invention of a highly electrically conductive concrete submerged in seawater. The figure shows a schematic diagram of the setup used to initiate and maintain the mineral accretion through the electrolysis process under lab conditions. The conductive concrete sample was deposited within a plastic box with sufficient seawater (natural or artificial) to cover all the sample, functioning as cathode; and a platinum-titanium anode was also placed inside the plastic box. The electrical current was applied through the electrical power supply. The electrolytic process is initiated and the mineral accretion is processed on the cathode, the electrically conductive concrete sample. The copper cable allows the electrical potential to be maintained at all points of the electrically conductive concrete. The electric current flows through concrete as shown in the present figure.

[0087] Figures 3 and 4 show precipitation of minerals like calcium carbonate and magnesium hydroxide on concrete through seawater electrolysis. The figures illustrate a bioactive layer formed by the imposition of the electrolytic process by the method mentioned in Figure 1 and Figure 2. These samples provide a good example of what is possible to do in just three days and in one month of exposure, with the electrolytic process with natural and artificial seawater, respectively. Both experiments were carried out under laboratory conditions. A significantamount of electrodeposited mineral materials was observed on practically the entire surfaces of conductive concrete, covering a great part of the concrete surface.

[0088] The embodiments described above are combinable.

[0089] The inventor wishes to acknowledge the support by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER), Project NQRTE-01-0145-FEDER-000032 - Next Sea.

[0090] References1. US Patent No. 4.246.075, January.1981, Inventor Wolf H. Hilbertz. "Mineral accretion of large surface structures".2. US Patent No. 4.440.605, April.1984, Inventor Wolf H. Hilbertz. "Repair of reinforced concrete by mineral accretion".3. Goreau T.J., "Marine Electrolysis for Building Materials and Environmental Restoration", INTECH, Chaper 13, 2012.4. Hilbertz W.H., "Electrodeposition of Minerals in seawater". IEEE Journal of Oceanic Engineering, July 1979.5. Schuhmacher H., Schillak L., "Integrated Electrochemical and Biogenic Deposition of Hard Material- a Nature-Like Colonization Substrate", Bulletin of Marine Science, 55(2-3):672-679, 1994.6. Zamani N.P., Bachtiar R., Madduppa H.H., Adi J.W., Iqbal M., Subhan B. "Study on Biorock Technique using three different anode materials (magnesium, aluminium and titanium)", E- journal llmu dan Teknologi Kelautan Tropics, Vol.2, No.l, Hal.1-8, June 2010.7. He Y., Lu L., Jin S., Hu S., Conductive aggregate prepared using graphite and clay and its use in conductive mortar. Construction and Building Materials 53. 2014; 131-137.8. Xie P., Gu P. Electrical percolation phenomena in cement composites containing conductive fibers. Journal of materials science 31. 1996; 4093-4097.9. Baeza F.J., Galao O., Vegas LJ., Cano M., Garces P. Influence of recycled slag aggregates on the conductivity and strain sensing capacity of carbon fiber reinforced cement mortars. Construction and Building Materials 184 (2018) 311-319.10. Chuang W., Geng-sheng J., Bing-liang L., Lei P., Ying F., Ni G., Ke-zhi L. Dispersion of carbon fibers and conductivity of carbon fiber-reinforced cement-based composites. Ceramics International 43. 2017; 15122-15132.El-Die b A. S., El-Ghareeb M.A., Abdel-Rahman M.A. H., Nasr E.S.A. Multifunctional electrically conductive concrete using different fillers. Journal of Building Engineering 15. 2018; 61-69. He Y., Lu L., Jin S., Hu S., Conductive aggregate prepared using graphite and clay and its use in conductive mortar. Construction and Building Materials 53. 2014; 131-137. Hou T., Nguyen V.K., Su Y.M., Chen Y.R., Chen P. Effects of coarse aggregates on the electrical resistivity of Portland cement concrete. Construction and Building Materials 133. 2017; 397- 408. Princiga Ho A., Breugel K., Levita G. Influence of the aggregate on the electrical conductivity of Portland cement concretes. Cement and Concrete Research 33. 2003; 1755-1763. Sassani A., Ceylan H., Kim S., Gopalakrishnan K., Arabzadeh A., Taylor P.C., Influence of mix design variables on engineering properties of carbon fiber-modified electrically conductive concrete. Construction and Building Materials 152. 2017; 168-181.

Claims

C L A I M S1. Use of a bioactive marine concrete as a marine structure, or as an artificial reef or coral, wherein the bioactive concrete comprises: a concrete comprising at least 50% (w / w) of conductive materials including aggregates and fibers; an electric circuit; and a mineral layer on the surface of the concrete.

2. Use of a bioactive marine concrete as a marine structure according to the previous claim wherein the concrete comprises cementitious material; fine additions; water; additives; at least 50% (w / w) of conductive materials including aggregates and fibers; an electric circuit; and a mineral layer on the surface of the concrete.

3. Use of a bioactive marine concrete according to the previous claim wherein the amount of water is at least 5% (w / w) and the amount of additive is at least 0.10% (w / w).

4. Use of the bioactive marine concrete according to any of the previous claims, wherein the concrete has an electrical resistivity equal or lower than 0.3 Q.m, preferably between 1.0 x 10-7fl. m and 0.3 1. m.

5. Use of the bioactive marine concrete according to any of the previous claims, wherein the electric circuit is composed of an electric power supply with direct current, a highly electrically conductive concrete functioning as a cathode that could be connected to a conductive wire, and an electrode functioning as an anode.

6. Use of the bioactive marine concrete according to any of the previous claims, wherein the electric circuit is a direct current electric circuit.

7. Marine structure, or an artificial reef or coral comprising concrete containing at least 50% of electrically conductive material; wherein the electrically conductive material is in the form of aggregate and fibers; fine additions; water, and additives.

8. Marine structure, or an artificial reef or coral according to the previous claim wherein the amount of electrically conductive aggregates is from 50%(w / w) to 70%(w / w), preferably 62%-65% (w / w).

9. Marine structure, or an artificial reef and coral according to any of the previous claimswherein the conductive aggregate is made of steel, iron, copper, aluminum, carbon, graphite or combinations thereof, preferably residues.

10. Marine structure, or an artificial reef or coral according to any of the previous claims wherein the micro electrically conductive fibers are made of carbon, steel or any other conductive material, including electrically conductive recycled fibers.

11. Marine structure, or an artificial reef and coral according to any of the previous claims wherein the electrically conductive aggregate comprises a density ranging from 1800 kg / m3- 3580 kg / m3.

12. Marine structure, or an artificial reef and coral according to any of the previous claims wherein the conductive aggregate size ranges from 0-50 mm, preferably from 0-4mm.

13. Marine structure, or an artificial reef and coral according to any of the previous claims further comprising electrically conductive fibers including recycled fibers, preferably carbon fiber.

14. Marine structure, or an artificial reef and coral according to any of the previous claims wherein the density of conductive fibers ranging from 1200 kg / m3 - 7850 kg / m3.

15. Marine structure, or an artificial reef and coral according to any of the previous claims further comprising additives selected from a list consisting of superplasticizer, plasticizer, and viscosity controller, or combinations thereof.

16. Method of obtaining the bioactive marine concrete according to any of the previous claims, comprising: immersing a fractured or a non-fractured concrete in a solution of electrolyte; connecting the concrete to a direct current electric circuit; subjecting the concrete to direct electric current to form a bioactive concrete and allow mineral accretion to form a mineral layer on the concrete surface.

17. Method according to the previous claim, wherein the solution of electrolyte is artificial seawater or natural seawater.

18. Method according to any of the previous claims 16 to 17, wherein the concrete issubjected to direct electric current for at least 1 day.

19. Method according to any of the previous claims 16 to 18, wherein the voltage is between 1 volt and 100 volts, and the electrical current is between 1 milli-amperes and 20 amperes.

20. Method according to any of the previous claims 16 to 19, wherein electrolyte has a salinity concentration of between 30%o e 35%o.

21. Method according to any of the previous claims 16 to 20, wherein the electrolyte has a salinity equal to the salinity of seawater.

22. Method according to any of the previous claims 16 to 21 wherein the electric circuit comprises an electric power supply with direct current, a highly electrically conductive concrete functioning as a cathode, and an electrode functioning as an anode.

23. Method according to any of the previous claims 16 to 22 wherein the electric circuit is a direct current electric circuit.

24. A method for producing bioactive marine concrete according to any of the previous claims, comprising the steps of: mixing concrete matrix comprising cementitious material, water and additives to form a concrete mixture; incorporating at least 50% (w / w) of electrically conductive material; wherein the electrically conductive material is in the form of aggregate and fibers into said concrete mixture to produce a bioactive marine concrete; incorporate the fine additions.