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    • 专利摘要:
    MICROCAPSULES AND CONCRETE CONTAINING THESE CONCRETE Microcapsules, for embedding in concrete, adapted to reduce the area of a weak spot in that concrete by at least 45% after fracturing a quantity of those microcapsules, each microcapsule comprising: a polymer shell around a liquid core, the polymer shell comprising a substantially impervious polymer layer and the liquid core comprising carbonatogenic bacterial spores, and optionally bacterial nutrients dispersed in a liquid environment. A concrete composition comprising an amount of such microcapsules and a method of reducing the area of a weak spot in concrete are also described.
    公开号:BE1021236B1
    申请号:E2013/0247
    申请日:2013-04-09
    公开日:2015-09-08
    发明作者:Hugo Soens；Belie Nele De；Jianyun Wang
    申请人:Devan Chemicals Nv；Universiteit Gent；
    IPC主号:
    专利说明:

    Microcapsules and concrete that contains them
    The present invention relates to micro-capsules for embedding in concrete or similar materials, which contain micro-organisms in the form of bacterial spores, which micro-capsules are adapted to reduce the surface area of a weak spot in that concrete (or similar material) after a amount of these microcapsules is broken. The invention also relates to a composition of concrete material or similar material that contains an amount of said microcapsules and is "self-healing" with respect to arbitrary weak spots in this composition.
    Concrete materials based on concrete and comparable to concrete are often used as preferred materials in construction projects due to their high compressive strength, high durability and low costs. Projects using such materials include constructions such as bridges, road construction projects, underground projects, water conservation and hydroelectricity projects, nuclear power stations, harbors and marine orphans, etc., as well as smaller-scale projects such as ramps, paving tiles, etc. materials contain usually have a long service life (of at least 5 years), but over time, the use and influence of environmental influences can lead to the formation of weak spots in these materials. Weak spots include visible cracks (with a width in millimeters), micro-cracks (with a width in micrometers), notches and cracks. If these weaknesses are not treated, one or more of these weaknesses can shorten the useful life of a structure and / or pose an immediate danger to the safety of that structure and its users.
    Although a concrete composition can be optimized in itself to improve the inherent resistance to weak spots, for example by suitable selection of the raw materials used, the mixing ratio thereof, whether or not certain additives are used, the production method, the casting processes and methods, It is known that weak spots always occur, with varying degrees of severity and over the course of a variable number of years from the curing of the concrete. Repairing weak spots in concrete or similar material in an appropriate and effective manner is therefore a constant concern for professionals in this sector, including scientists and engineers.
    We know that certain concrete compositions exhibit a degree of self-repair in certain circumstances, namely automatic repair, of weak spots therein. Usually in the concrete matrix of relatively recently placed concrete and high-strength concrete are non-hydrated cement particles; when water becomes available in weak spots that may have formed in such concrete, the hydration of the non-hydrated cement particles present in the weak spot is initiated, which leads to a certain degree of repair or repair of the relevant concrete. weak spot. It is generally assumed that there are two mechanisms by which an automatic repair may occur depending on the secondary hydration of non-hydrated cement particles present in the concrete composition: (1) the resulting deposit of calcium carbonate and (2) the swelling of the hydration products to reduce the area of the weak spot. With the mechanism (1), carbon dioxide (CO2) can dissolve from the surrounding atmosphere in the water to form carbonate anions (CO32 ') in the alkaline environment of the concrete (the pH of concrete is approximately 12.5-13). Dissolved free calcium cations (Ca 2+) that are caused by the weak spot can then react with the carbonate anions to form calcium carbonate. However, such self-repair is highly dependent on the age of the concrete, the water / cement ratio and the water available in the vicinity of the weak spot.
    We also know, for example from the document EP 2 239 242 A1, a self-repairing or 'self-repairing' concrete that contains a number of polymeric, resin-containing microcapsules of urea-formaldehyde, melamine-formaldehyde and / or urea-melamine-formaldehyde with an adhesive, that are distributed over the entire concrete structure. The described adhesives include one-component adhesives such as polyurethanes, organic silicon with anaerobic organisms, acrylic resins and chloroprene rubbers, and multi-component adhesives such as epoxy resins. As soon as a crack appears in the concrete, microcapsules in the vicinity of the crack release the enclosed adhesive to repair the crack under the influence of a stress caused by the crack.
    However, a number of technical problems may arise, including a correspondence between the walls of the crack in the concrete and the adhesive materials used for the repair, the extent to which the adhesive flows prior to curing to repair the crack, the durability of the adhesive and the resulting consequences (such as a local weakening) for the concrete immediately adjacent to the repaired crack, making it necessary to propose a solution with such an invention.
    As a result, the repair of weak spots in concrete materials and similar materials, preferably by automatic repair, must always be addressed in order to avoid the need for human or mechanical intervention in determining and carrying out a repair, in a manner as appropriate as possible to propose a suitable and sustainable solution.
    First aspect
    Thus, in a first aspect, the present invention proposes microcapsules for embedding in concrete, a concrete-based material and a similar concrete material, adapted to reduce the surface area of a weak spot in that material after an amount of those microcapsules is broken wherein said microcapsules each include the following: a polymeric envelope around a liquid core, the polymeric envelope comprising a substantially impervious polymer layer and the liquid core comprising carbonatogenic bacterial spores dispersed in a liquid, and wherein at least one of the following criteria (i) - (iii) are met: (i) the polymer layer comprises a polymer selected from the group consisting of: gelatins,
    Polyurethanes, polyolefins, polyamides,
    Polysaccharides, silicone resins, epoxy resins, chitosane, aminoplast resins and derivatives thereof and / or (ii) the bacterial spores are selected from a group of bacteria consisting of: Bacillus cereus, Bacillus subtilis, Bacillus sphaericus, Bacillus lentus, Bacillus pasteurii, Bacillus megaterium , Bacillus cohnii, Bacillus halodurans, Bacillus pseudofirmas, Myxococcus Xanthus and mixtures thereof and / or (iii) the liquid is a non-aqueous, water-immiscible liquid selected from the group consisting of: organic oils, mineral oils, silicone oils , fluorocarbons, esters and mixtures thereof, so that when an amount of these microcapsules is present in the material, the area of the weak spot in that material can be reduced by at least 45% with respect to a starting area of the weak spot after at least some of the microcapsules from that amount are broken.
    Such microcapsules have the ability, after being incorporated into a composition of concrete material or similar material, to reduce the surface of a weak spot, such as a crack or notch in that material, after a number of those microcapsules are broken. The breaking of the microcapsules is achieved under the influence of an internal stress that is created locally in the concrete around the weak spot. In addition to the internal stress, however, an external influence such as a force or a higher / lower temperature can be exerted to influence the inherent brittleness of the microcapsules and to cause the fracture. After being broken, the microcapsules in question release their entrapped contents and thereby permit the repair of the weak spot in the most appropriate manner to provide a suitable and durable solution.
    Microcapsules according to the invention can be produced by any suitable technique for manufacturing microcapsules known in the art, including, but not limited to, coacervation, interfacial polycondensation polymerization, emulsion polymerization by addition or in situ, and suspension polymerization by addition or in situ, to produce microcapsules with the desired size, brittleness and insolubility in water. In general, methods such as coacervation and interfacial polymerization can be used in a known manner to produce microcapsules with the desired properties. Such methods are described in the documents US 3 870 542, US 3 415 758 and US 3 041 288.
    To avoid doubt, even breaking a single microcapsule would promote a certain degree of reduction in the area of the weak spot, but to ensure that the results are not negligible and a visible recovery can be observed, a amount of microcapsules (larger in number than one microcapsule, preferably at least 104 microcapsules per cm 2 of the surface of the weak spot, and generally in the order of 106 microcapsules per cm 2 of the surface of the weak spot) break.
    Preferably for microcapsules according to the first aspect of the invention, regardless of which two of the three criteria (i) - (iii) are met, with the criteria (i) and (ii) being preferred. Even more preferably, however, all three criteria (i) - (iii) can be met for such microcapsules.
    To achieve the described percentage surface reduction, the concentration of bacterial spores in each microcapsule may preferably be at least 109 spores per gram (dry weight) of microcapsule.
    Second aspect
    In a second aspect, the invention proposes microcapsules for embedding in concrete, a concrete-based material and a similar concrete material, which are adapted to reduce the surface of a weak spot in that material after an amount of said microcapsules is broken, wherein said microcapsules each comprising: a polymeric shell around a liquid core, the polymeric shell comprising a substantially impervious polymer layer and the liquid core comprising carbonatogenic bacterial spores dispersed in a liquid, and wherein the concentration of bacterial spores in each microcapsule is at least 109 per gram (dry weight) of the microcapsule, so that when an amount of these microcapsules is present in the material, the area of the weak spot in that material can be reduced by at least 4% relative to an initial area of the weak spot after at least some of the microcapsules from that amount were born are smoking.
    The liquid in which the bacterial spores are spread is preferably a non-aqueous, water-immiscible liquid.
    As with the first aspect of the invention, such microcapsules have the ability, after being incorporated into a composition of concrete material or similar material, to reduce the surface of a weak spot, such as a crack or notch in that material, after a number of that microcapsules is broken, with all associated benefits described above. Again, such microcapsules can be manufactured by any suitable microcapsule manufacturing technique such as those described above.
    Advantageously, the liquid core of some or all of the microcapsules according to one or the other of the first or the second aspect may furthermore comprise bacterial nutrients. This is because the nutrients can be enclosed in certain or all microcapsules together with the carbonatogenic bacterial spores. With such a joint encapsulation in a capsule, the bacterial nutrients, upon breaking a relevant microcapsule and the distribution of its contents, are readily available to agitate with atmospheric oxygen and ambient water to allow the germination of bacterial spores to form vegetative bacteria thus promoting the production of calcium carbonate, as will be described in more detail later in this paper.
    Third aspect
    In a third aspect, the invention proposes microcapsules for embedding in concrete, a concrete-based material and a similar concrete material, adapted to reduce the surface of a weak spot in that material after an amount of said microcapsules is broken, wherein said microcapsules each comprising: a polymeric shell around a liquid core, the polymeric shell comprising a substantially impervious polymer layer and the liquid core comprising carbonatogenic bacterial spores and bacterial nutrients scattered in a liquid environment.
    According to this third aspect of the invention, the nutrients are enclosed in the microcapsules together with the carbonatogenic bacterial spores, irrespective of the concentration or variety of the bacterial spores (other than carbonatogenic), the nature of the polymer layer and the nature of the liquid environment .
    As with any of the first and second aspects of the invention, such microcapsules have the ability, after being incorporated into a concrete or similar material composition, to surface the weak spot, such as a crack or notch in that material. shrink after a number of those microcapsules are broken. Again, such microcapsules can be manufactured by any suitable microcapsule manufacturing technique such as those described above.
    In a preferred embodiment according to the third aspect of the invention, when there is an amount of such microcapsules in that concrete material or similar material, the surface area of the weak spot in the material can preferably be reduced by at least 45% relative to an initial surface of the weak spot after at least some of the microcapsules have been broken from that amount. To achieve the described percentage surface reduction, the concentration of bacterial spores in each microcapsule may preferably be at least 109 spores per gram (dry weight) of microcapsule.
    Reducable area of the weak spot
    In the microcapsules according to any of the first, second or third aspect of the invention, the area of the weak spot in the concrete material or similar material can be reducible by at least 50%, preferably by at least 60%, with even more preferably by at least 70% and ideally by at least 80% relative to the initial surface of that weak spot after at least a few microcapsules have been broken from that amount.
    Advantageously, the reducible surface of the weak spot can be determined after a continuous wet-drying cycle of 4 weeks, starting with a wet phase that immerses the concrete material or similar material, or at least of the surface in which the weak spot is located, in water for 12 to 20 hours, preferably 16 hours, followed by a dry phase in which the concrete material or similar material, or at least the surface in which the weak spot is located, is in air (at ambient temperature, such as 20 ° C, at a relative humidity of 50 to 70%, preferably 60% for 6 to 10 hours, preferably 8 hours. Such conditions are believed to promote at least 45% reduction in the area of weakness described above.
    Polymer layer
    The polymer layer of the microcapsules according to the second or third aspect of the invention may comprise a polymer selected from the group consisting of: gelatins, polyurethanes, polyolefins, polyamides, polysaccharides, silicone resins, epoxy resins, chitosane, aminoplast resins and derivatives and mixtures thereof. These are the same polymers as for the first aspect of the invention. Many of these types of encapsulating materials for polymeric microcapsules are further described and illustrated in the document US 3 870 542.
    Preferably, the polymer layer of any of the aforementioned aspects comprises a polymer selected from the group consisting of: Vinyl polymers, acrylate polymers, acrylate-acrylamide polymers, melamine-formaldehyde polymers, urea-formaldehyde polymers, and mixtures and derivatives thereof.
    Highly preferred materials for the casing wall of the microcapsule are aminoplast polymers which include the reaction products of, for example, urea or melamine and an aldehyde, for example formaldehyde. Even more preferably, the polymer layer can thus be a melamine formaldehyde resin or comprise a layer of that polymer. Such materials are materials capable of polymerizing in an acid state based on a water-soluble prepolymer or a precondensate state. Polymers formed from such precondensate materials in the acidic state are not water-soluble and can provide the required brittleness characteristics of the microcapsule that allow the next fracture of the microcapsule.
    Even more preferably, the casing wall of the microcapsule can be formed by a network of bridged polymers comprising a copolymer of melamine and formaldehyde: acrylic acrylamic acid.
    Microcapsules made on the basis of aminoplast polymer coating materials can be produced by an interfacial polymerization method as described in the document US 3 516 941: an aqueous solution of a precondensate (methylol urea) is formed, which is about 3 to 30 weight percent of the precondensate. In this entire solution, a non-aqueous and water-immiscible liquid is dispersed in the form of separate droplets with microscopic dimensions. While the temperature of the solution is maintained at 20 ° C to 90 ° C, an acid is added to catalyze the polymerization of the dissolved precondensate. If the solution is rapidly shaken during this polymerization phase, sheaths of water-soluble aminoplast polymer form around the dispersed liquid droplets, trapping the droplets and forming a liquid core. Microcapsules according to the present invention can be produced by a similar process in which the carbonatogenic bacterial spores are dispersed in the liquid core prior to polymerization.
    The polymer layer of the microcapsules according to any of the aforementioned aspects may furthermore comprise functional reactive groups extending to the outside of the microcapsules, whereby the microcapsule can be chemically bonded in the concrete material or similar material. Such a functional reactive group preferably comprises a characteristic reactive group adapted to provide a covalent bond in the concrete.
    Bacterial spores
    The bacterial spores according to the second or third aspect of the invention can be selected from the group of bacteria consisting of: Bacillus cereus, Bacillus subtilis, Bacillus sphaericus, Bacillus lentus, Bacillus pasteurii, Bacillus megaterium, Bacillus cohnii, Bacillus halodurans, Bacillus pseudofirmas, Myxococcus Xanthus and mixtures thereof. Such carbonatogenic bacteria, namely bacteria that produce carbonate (CO32 ') and bicarbonate (HCO3'), can be used to produce calcium carbonate to achieve the desired repair of weak spots in concrete (or similar material), as will be described in more detail below. to become.
    Preferably, the bacterial spores of any of the aforementioned aspects of the invention can be selected from the group of bacteria consisting of: Bacillus sphaericus, Bacillus pasteurii and Bacillus cohnii, as these are the best performing for the present purposes in connection with carbonatogenesis. Even more preferably, the bacterial spores can be selected from the group of bacteria consisting of: Bacillus sphaericus and Bacillus pasteurii.
    Liquid
    The liquid, preferably non-aqueous and non-water-miscible, of the microcapsules according to the second or third aspect of the invention can be selected from the group consisting of: organic oils, mineral oils, silicone oils, fluorocarbons, esters and mixtures thereof. "Not watery" means that the liquid contains less than 0.1% by weight of water. "Water immiscible" means that the water solubility of the liquid (and vice versa) is less than 1%, because that promotes the formation of the microcapsules through a range of emulsion polymerization.
    For the liquid, a silicone oil is preferred which preferably has a kinematic viscosity of 500 centistokes (mm 2 / sec) or less, preferably 350 centistokes (mm 2 / sec) or less at 25 ° C.
    Size and content
    Microcapsules according to any of the aforementioned aspects of the invention can each have an average diameter of more than 0.5 μτα, preferably more than 1 μτα. The average diameters of the microcapsules may, for example, be in the range of 0.5 to 50 μτα or 1 to 20 μιη.
    Preferably, the bacterial spores dispersed in the fluid of each microcapsule according to any of the aforementioned aspects of the invention may together constitute 40 to 70 volume percent of the volume in the polymeric shell of each microcapsule.
    Even more preferably, the bacterial spores may represent at least 1, preferably at least 2, volume percent of the volume of the fluid in each microcapsule.
    Bacterial nutrients
    The bacterial nutrients described with respect to the microcapsules of any of the aforementioned aspects of the invention may include: urea (CO (NH 2) 2), a suitable source of carbon and nitrogen, such as a bacterial culture, yeast, a yeast extract, and a suitable source of calcium, such as hydrated calcium nitrate (Ca (NO 3) 2 · 4H 2 O), calcium chloride, calcium acetate, calcium lactate and analogous substances.
    In addition to new and innovative microcapsules per se, the present invention also proposes new and innovative concrete compositions that are "self-healing" and contain such microcapsules.
    Fourth aspect
    Accordingly, a fourth aspect of the present invention proposes a concrete composition, a concrete-based material and a similar concrete material comprising the following: a cement material, one or more aggregates, a liquid binder and an amount of microcapsules according to the first and / or or second aspect of the invention, whereby, after curing of the concrete, the area of a weak spot therein can be reduced by at least 45% with respect to a starting area of the weak spot after at least some of the microcapsules have broken out of that amount to be.
    Fifth aspect
    A fifth aspect of the present invention proposes a concrete composition, a concrete-based material and a similar concrete material comprising the following: a cement material, one or more aggregates, a liquid binder and an amount of microcapsules according to the third aspect of the invention.
    Sixth aspect
    A sixth aspect of the present invention proposes a method for reducing the surface of a weak spot (relative to a starting surface of the weak spot) in concrete, a material based on concrete and / or similar concrete material, which comprises the following phases comprises: (i) providing a concrete composition, a concrete-based material and / or similar concrete material according to the fourth and / or fifth aspect of the invention containing an amount of microcapsules; (ii) curing the composition; and (iii) breaking at least some of the microcapsules from that amount in response to the creation and / or aggravation of a weak spot in that cured composition, thus releasing the content of the microcapsules to reduce the weak spot to bring about.
    When the material has taken the form of hardened concrete, the area of a weak spot in that material can be reduced by at least 45% with respect to a starting area of the weak spot after at least some of the microcapsules have been broken from that amount.
    The presence of microcapsules according to any of the aforementioned aspects of the invention in such concrete or similar material compositions means that the area of a weak spot, such as a crack or notch in that material, can be reduced by at least 45% after an amount of those microcapsules is broken, and therefore a degree of self-recovery is possible. The breaking of the microcapsules is achieved under the influence of an internal stress that is created locally in the concrete around the weak spot. In addition to the internal stress, however, an external influence such as a force or a higher / lower temperature can be exerted to influence the inherent brittleness of the microcapsules and to cause the fracture. After being broken, the microcapsules in question release their entrapped contents and thereby permit the repair of the weak spot in the most appropriate manner to provide a suitable and durable solution.
    To avoid doubt, even breaking a single microcapsule would promote a certain degree of reduction in the area of the weak spot, but to ensure that the results are not negligible and a visible recovery can be observed, a amount of microcapsules (larger in number than one microcapsule, preferably at least 104 microcapsules per cm 2 of the surface of the weak spot, and generally in the order of 106 microcapsules per cm 2 of the surface of the weak spot) break.
    To their surprise, the inventors discovered that the bacterial spores were able to support the microcapsule formation process so that they could always germinate to initiate ureaytic activity to dissolve the urea (present in bacterial nutrients). The bacterial spores thus remain dormant in the microcapsules.
    Without wishing to be bound by any theory, it is thought that the repair mechanism follows the following path: (1) Breaking the microcapsule - release of the bacterial spores for exposure to germination activators: oxygen, water and bacterial nutrients (2) Germination of bacterial spores -> production of vegetative bacterial cells for use in hydrolysis (3) Deposition of calcium carbonate for repair of the weak spot by means of: (a) CO (NH2) 2 + 2H20 - »2NH4 + + C032" [catalyzed by bacterial urease] (b) Ca 2+ + CO 32 '- »CaCO 3
    The formation of the weak spot, for example the formation of a crack, causes the microcapsules to break in the vicinity of the crack, thereby releasing the liquid core. In the presence of oxygen, water and bacterial nutrients, the bacterial spores in the liquid core begin to germinate so that the ureolytic activity can begin. The urea is decomposed by the germinated bacteria (catalyzed by bacterial urease) at an alkaline pH in CO232 and NH3 / NH4 +. When CO32 "ions come into contact with Ca2 + ions (e.g. from calcium), CaCO3 is formed.
    A concrete composition according to the fourth or fifth aspect of the invention, which comprises microcapsules with carbonatogenic bacterial spores according to the first, second and / or third aspect of the invention, is thus advantageous with respect to concrete compositions according to the preceding technique because it has the desired interfacial compatibility between the walls of a weak spot in the concrete and the calcium carbonate produced in situ that is used for the repair. Moreover, there is no limitation on the extent to which the calcium carbonate produced in situ is produced to allow for the recovery of the weak spot, provided that the microcapsules are distributed equally throughout the concrete composition. Moreover, due to the correspondence between the repair material and the concrete, the repair has the desired service life and durability. Also, regardless of the logical consequences (such as local weakening) for the concrete immediately adjacent to the repaired crack, it is kept to a minimum, again by the correspondence between the repair material and the concrete.
    The surface of the weak spot in the concrete that can be formed from the composition of the fourth or fifth aspect of the invention can be reducible by at least 50%, preferably by at least 60%, even more preferably by at least 70 % and ideally by at least 80% relative to the initial surface of that weak spot after at least a few microcapsules have been broken from that amount.
    Advantageously, the reducible surface of the weak spot can be determined after a continuous wet-drying cycle of 4 weeks, starting with a wet phase that immerses the concrete material or similar material, or at least of the surface in which the weak spot is located, in water for 12 to 20 hours, preferably 16 hours, followed by a dry phase in which the concrete material or similar material, or at least the surface in which the weak spot is located, is in air (at ambient temperature, such as 20 ° C, at a relative humidity of 50 to 70%, preferably 60% for 6 to 10 hours, preferably 8 hours. Such conditions are believed to promote at least 45% reduction in the area of weakness described above.
    Microcapsule dosage
    Advantageously, the amount of microcapsules present in the composition according to the fourth or fifth aspect of the invention is, depending on the dry weight, in the range of 1 to 10, preferably 2 to 8, weight percent of the cement material.
    In one embodiment, the microcapsules may be added to the composition in the form of an emulsion in which the microcapsules are dispersed, particularly when the microcapsules are formed by an emulsion polymerization process. Even more preferably, the emulsion can be a water-based emulsion.
    Bacterial nutrients
    A concrete composition according to the fourth or fifth aspect of the invention may (in the case of the fourth aspect) or may additionally (in the case of the fifth aspect) comprise bacterial nutrients, which preferably together with the cement material, the additive material, the liquid binder and the microcapsules, which themselves may or may not contain bacterial nutrients, are added to the actual concrete composition.
    The bacterial nutrients can thus be included in the composition by any of the following means: - by direct addition to the composition; - by adding a quantity of different microcapsules with the nutrients; - by adding a hydrogel or other suitable carrier, for example a porous aggregate or diatomaceous earth, which contains the nutrients.
    The amount of bacterial nutrients contained in the composition may advantageously be in the range of 10 to 20, preferably 12 to 18, weight percent of the cement material. Ingredients of concrete
    In a concrete composition according to the fourth and fifth aspect of the invention, the cement material is preferably cement. A typical suitable cement is Portland cement, but any other suitable cement material can also be used.
    In a concrete composition according to the fourth and fifth aspect of the invention, the aggregate material is preferably a mixture of fine and coarse aggregate materials, with particles of different sizes, including materials such as sand, natural gravel, crushed stone and / or recycled materials obtained from construction , demolition or excavation waste.
    In a concrete composition according to the fourth and fifth aspect of the invention, the liquid binder is preferably water.
    Advantageously, the cement / additive / water ratio in a concrete composition according to the fourth and fifth aspect of the invention can be in a range of (0.5 to 1.5): (1 to 15): (0.1 to 1), the 1: 5: 0.5 ratio being preferred.
    For a better understanding, the present invention will now be more particularly described with reference to exclusively non-exhaustive examples, with reference to the accompanying figures, in which: Figure 1 shows a series of graphs (a) to (f) for a number of different cement samples (R, N, C, NC, NCS3% and NCS5% groups respectively) from the initial surface of the crack (mm2) compared to the final surface of the crack (mm2), after being subjected to different incubation states (1) through (Figure 2) is a graph of the absolute value of the restored area (mm 2) for the cement samples shown in Figures 1 (a) to ml (f), for the incubation states (1) t and (3) and Figure 3 is a graph of the recovery growth for the cement samples shown in Figures 1 (a) to 1 (f) and Figure 2 for the incubation states (1) to (5).
    Six cement compositions have been prepared, as shown in Table 1 below. The samples from 'Group R' are control samples prepared without any addition to the basic composition of cement, sand and water. The samples from 'Group N' were prepared with bacterial nutrients from (i) yeast, (ii) urea and (iii) tetrahydrated calcium nitrate in the amounts 0.85, 4 and 8 weight percent of the cement, as the only addition in comparison with the control samples. The samples from 'Group C' were prepared with control microcapsules (without any bacterial trace) in an amount of 3% by weight of the cement. For example, the samples from "Group NC" are prepared according to a combination of the samples from "Group N" and "Group C", with bacterial nutrients and 3 weight percent microcapsules without any bacterial spore. "Group NCS3%" and "Group NCS5%" are prepared with bacterial nutrients (such as the samples from "Group N") and 3 to 5 percent by weight (of the cement) of microcapsules containing bacterial spores in a concentration of 109 per gram microcapsule (dry weight).
    Table 1
    Consequently, to compensate for the 30.5% by weight of the water of hydration in the tetrahydrated calcium nitrate for the samples containing added bacterial nutrients (groups N, NC, NCS3% and NCS5%), the amount of water added to the composition was limited to compared to the amount of 225 g. Similarly, to compensate for the water in the emulsion (in which the microcapsules are added to the compositions) for the samples containing added microcapsules (groups C, NC, NCS3% and NCS5%), the amount added to the composition was water is therefore limited, or further limited, with respect to the amount of 225 g.
    For each of the six groups of assemblies, five long armed prisms were made (with dimensions of 30 x 30 x 360 mm, the internal reinforcement having a length of 660 mm and a diameter of 6 mm) - thus a total of thirty samples. After casting, the molds were placed in a room with climate control (at 20 ° C,> 90% RL). The samples from the control group R were removed from the mold after 24 hours, while the samples from other groups were removed from the mold after 4 hours due to a slower cure by the additions during the first 24 hours. After removal from the mold, all samples were stored in the same room until the time of the test. 2 days after casting, each of the long armed prisms was subjected to a tensile test to cause multiple cracks. The reinforcement of the prism was mounted in a test machine (Amsler 100, SZDU 230, Switzerland), the distance between the glue clamp and the side surface being 50 mm. After relieving the load, the reinforcement was cut (leaving a protruding portion of about 140 mm from each end of the prisms) and the remaining reinforcement was wrapped with aluminum tape to prevent iron corrosion during subsequent immersion.
    After causing cracks, the long prisms were subjected to five incubation states:
    (1) 20 0 C,> 90% RL (2) complete and continuous immersion in water (3) complete and continuous immersion in a deposit environment (4) continuous wet-dry cycle with water (5) continuous wet-dry cycle with the deposit environment.
    The deposition environment consisted of 0.2 M urea and 0.2 M Ca (NO 3) 2
    During the dry-wet cycles, the samples were immersed in water / the sediment environment for 16 hours and then exposed to air for 8 hours. The incubation states of (2), (3), (4) and (5) were achieved in a room with climate control (20 ° C, 60% RL). When the samples were immersed, they were not in contact with the bottom of the immersion vessel, but a certain distance (about 5 mm) was maintained between the samples and the bottom. Four surfaces of 60 mm x 30 mm were named A, B, C and D to represent the different states of contact with water: surface B and C, respectively, were the top and bottom surfaces, while surface A and D were the two side surfaces goods.
    The cracks formed in each sample were determined and counted per incubation condition; the results are shown in Table 2 below.
    Table 2
    The first optical microscopic images of the cracks in the samples were taken immediately after the formation of different cracks. Each crack was divided into 10 to 11 sections by pencil marks to ensure that the entire crack was micro-photographed with a minimal overlap of the surface between the images.
    During the incubation period under different conditions, the samples were examined every week in the first month and at the end of the second month by optical microscopy. The initial and final values of the tear surfaces on the images were determined with an image analysis program of
    X TM
    Leica.
    Although the same methodology was used to cause the cracks in each of the samples, the cracks clearly behaved differently due to the different mechanical properties of the samples caused by their different compositions. As Table 2 shows, the number of cracks per sample varied from 13 to 35 and the width of the crack varied from 5 0 μτη to 9 0 0 μπι.
    The efficiency of the self-repair, or the extent of the weak spot repair (crack), of each of the samples was assessed by determining the absolute crack area (Ah).
    The recovery efficiency of the crack was also assessed using the recovery increase (the amount of cracking area filled by the deposit), which was calculated using the equation below. The recovery rate can indicate the potential recovery rate in the absence of specific data about the cracks (width, area, etc.) from practice.
    where: 'r' is the recovery growth of the crack, 'Ai' is the initial crack surface (mm2) 'Af' is the final crack surface (mm2)
    It is clear to see that the surface of the crack has gradually decreased over time. The crack surface was almost fully recovered within three weeks. However, to quantify the recovery efficiency, the cumulative recovered tear area of each sample was calculated after eight weeks based on the total initial tear area (Ai) and the total final tear area (Af), which is shown in the accompanying figure 1.
    As can be seen in Figure 1, after eight weeks the tear area had decreased for all samples (shown in graphs (a) to (f)), with the exception of the samples incubated in state (1) (in a space with climate control, at 2 0 ° C and 95% RL), for which no observable recovery was observed with optical microscopy. In each graph, a pair of "coupled" bars represents the incubation state (1) through (5), the total initial tear surface (Ai) being represented by the left bar of each pair and the total final tear surface (Af) being represented by the right bar of each pair.
    The absolute value of the recovered tear area (Ah) shown in Figure 2 provides a pure comparison of the recovery efficiency, while the recovery increase (r) provides a means to compare recovery efficiencies with respect to the original tear area per sample, as shown in Figure 3.
    Crack recovery was observed for all samples with the exception of the samples stored at 95% RL. A significant amount of crack recovery (automatic recovery) was observed for the micro-capsule-free samples when immersed or subjected to a wet-drying cycle. The recovered tear surface (Ah) ranged from 12.6 mm 2 to 57.8 mm 2 depending on the specific sample and the incubation condition.
    Compared with samples without bacteria in microcapsules, the recovery efficiency (r) of samples with bacteria in microcapsules was much higher. The recovered tear surface (Ah) ranged from 49.3 mm 2 to 8 mm 2. Regarding the total repaired crack area, no significant difference was noted between the NCS3% and NCS5% series, but the specific recovery efficiency of each sample of NCS3% and NCS5% was different depending on the incubation condition. The maximum recovered tear area (approximately 80 mm 2) was observed in samples that had been subjected to the wet-drying cycle with water, although the samples showed similar recovery efficiencies in other incubation states.
    The crack recovery gain (r) of each sample from the different series is shown in Figure 3. The samples without bacteria in microcapsules showed a recovery gain (r) in the range of 18% to 50%. No significant difference in recovery growth was found between the different series (R, N, C and NC).
    The samples with bacteria in microcapsules showed a much higher recovery rate (r), ranging from 48% to 80%. The highest value was reached in the NCS3% sample, which was subjected to an incubation state (4).
    The samples with bacteria in microcapsules showed a much higher efficiency of self-recovery; when the samples were subjected to an incubation state (4), the recovered tear area was about six times as large as that of the "R Group" control series. With regard to the repaired crack surface, the repaired surface of the samples from the non-bacterial groups (R, N, C, NC) ranged from 12.6 mm 2 to 57.8 mm 2, while the repaired surface of the groups with bacteria ( NCS3% and NCS5%) ranged from 49.3 mm 2 to 80 mm 2. The maximum recovered crack width of the samples from the groups with bacteria was 97 0 μιη, which is much more than that of the samples from the groups without bacteria (maximum 250 μπ ).
    权利要求:
    Claims (36)
    [1]
    CONCLUSIONS
    Microcapsules, for inclusion in concrete, adapted to reduce the surface of a weak spot in that concrete after an amount of said microcapsules is broken, the microcapsules each comprising the following: a polymer shell around a liquid core, the The polymeric shell comprises a substantially impervious polymer layer and the liquid core comprises carbonatogenic bacterial spores dispersed in a liquid, and wherein at least one of the following criteria (i) - (iii) is met: (i) the polymer layer comprises a polymer selected from the group consisting of: gelatins, polyurethanes, etc. polyolefins, polyamides, polysaccharides, silicone resins, epoxy resins, chitosane, aminoplast resins and derivatives thereof and / or (ii) the bacterial spores are selected from a group of bacteria consisting of: Bacillus cereus, Bacillus subtilis, Bacillus sphaericus, Bacillus lentus, Bacillus pasteurii, Bacillus megaterium, Bacillus cohnii, Bacillus halodurans, Bacillus pseudofirmas, Myxococcus Xanthus and mixtures thereof and / or (iii) the liquid is a non-aqueous, water-immiscible liquid selected from the group consisting of: organic oils, mineral oils, silicone oils, fluorocarbons, esters and mixtures thereof, so that when there is an amount of these microcapsules in the concrete, the area of the weak spot therein can be reduced by at least 45% with respect to an initial area of the weak after at least some of the microcapsules have broken out of that amount.
    [2]
    Microcapsules according to claim 1, wherein regardless of which two of the three criteria (i) - (iii) are met.
    [3]
    Microcapsules according to claim 2, wherein all three criteria (i) - (iii) are met.
    [4]
    Microcapsules according to any preceding claim, wherein the concentration of bacterial spores in each microcapsule is at least 109 per gram (dry weight) of microcapsule.
    [5]
    5. - Microcapsules, for embedding in concrete, adapted to reduce the surface of a weak spot in that concrete after an amount of those microcapsules is broken, the microcapsules each comprising the following: a polymer shell around a liquid core, the polymeric envelope comprises a substantially impervious polymer layer and the liquid core comprises carbonatogenic bacterial spores dispersed in a liquid, and wherein the concentration of bacterial spores in each microcapsule is at least 109 per gram (dry weight) microcapsule, so that when there is an amount of these microcapsules are present in the concrete, the area of the weak spot therein can be reduced by at least 45% with respect to a starting area of the weak spot after at least some of the microcapsules have been broken from that amount.
    [6]
    Microcapsules according to any preceding claim, wherein the liquid core further comprises bacterial nutrients.
    [7]
    7. - Microcapsules, for embedding in concrete, adapted to reduce the surface of a weak spot in that concrete after an amount of those microcapsules is broken, the microcapsules each comprising the following: a polymer shell around a liquid core, the The polymeric shell comprises a substantially impervious polymer layer and the liquid core comprises carbonatogenic bacterial spores and bacterial nutrients scattered in a liquid environment.
    [8]
    A microcapsules according to claim 7, wherein, when an amount of these microcapsules is present in the concrete, the surface of the weak spot therein can be reduced by at least 45% with respect to a starting surface of the weak spot after at least a few of the microcapsules from that amount are broken.
    [9]
    Microcapsules according to one of claims 1 to 6 and 8, wherein the surface of the weak spot in the concrete can be reduced by at least 50%, preferably by at least 60%, even more preferably by at least at least 70% and ideally with at least 8% relative to the initial surface of that weak spot after at least a few microcapsules have been broken from that amount.
    [10]
    Microcapsules according to any of claims 1 to 6, 8 and 9, wherein the diminutable surface area of the weak spot is determined after a continuous wet-drying cycle of 4 weeks, the wet phase immersing the concrete in water for 16 hours, followed by the dry phase in which the concrete is exposed to the air for 8 hours (at 20 ° C and a relative humidity of 60%).
    [11]
    A microcapsules according to claim 5 or claim 7, wherein the polymer layer comprises a polymer selected from the group consisting of: gelatins, polyurethanes, polyolefins, polyamides, polysaccharides, silicone resins, epoxy resins, chitosane, aminoplast resins and derivatives and mixtures thereof.
    [12]
    A microcapsules according to claim 5, 7 or 11, wherein the bacterial spores are selected from the group of bacteria consisting of: Bacillus cereus, Bacillus subtilis, Bacillus sphaericus, Bacillus lentus, Bacillus pasteurii, Bacillus megaterium, Bacillus cohnii, Bacillus halodurans, Bacillus pseudofirmas, Myxococcus Xanthus and mixtures thereof.
    [13]
    Microcapsules according to any of claims 5, 7, 11 or 12, wherein the liquid is selected from the group consisting of: organic oils, mineral oils, silicone oils, fluorocarbons, esters and mixtures thereof.
    [14]
    A microcapsules according to claim 1 or claim 11, wherein the polymer layer comprises a polymer selected from the group consisting of: Vinyl polymers, acrylate polymers, acrylate acrylamide polymers, melamine-formaldehyde polymers, urea-formaldehyde polymers and mixtures and derivatives thereof.
    [15]
    Microcapsules according to claim 14, wherein the polymer layer comprises a melamine formaldehyde resin.
    [16]
    Microcapsules according to any of claims 1, 11, 14 or 15, wherein the polymer layer comprises functional reactive groups which extend to the outside of the microcapsules, whereby the microcapsule can be chemically bonded in the concrete.
    [17]
    A microcapsules according to claim 16, wherein a functional reactive group comprises a characteristic reactive group adapted to provide a covalent bond in the concrete.
    [18]
    A microcapsules according to claim 1 or claim 12, wherein the bacterial spores are selected from the group of bacteria consisting of: Bacillus sphaericus, Bacillus pasteurii and Bacillus cohnii.
    [19]
    A microcapsules according to claim 1 or claim 13, wherein the liquid is a silicone oil.
    [20]
    A microcapsules according to any preceding claim, wherein each has a diameter greater than 0.5 μτη, preferably greater than 1 μιη.
    [21]
    A microcapsules according to any preceding claim, wherein the bacterial spores dispersed in the fluid together make up 40 to 70 volume percent of the volume in the polymeric shell of each microcapsule.
    [22]
    Microcapsules according to any preceding claim, wherein the bacterial spores make up at least 1, preferably at least 2, volume percent of the volume of the fluid in each microcapsule.
    [23]
    Microcapsules according to claim 6 or claim 7, wherein the bacterial nutrients comprise one or more of the following components: urea, a suitable source of carbon and nitrogen, such as a bacterial culture, yeast, a yeast extract, and a suitable source of calcium, such as hydrated calcium nitrate, calcium chloride, calcium acetate or calcium lactate.
    [24]
    A concrete composition comprising: a cement material, one or more aggregates, a liquid binder and an amount of microcapsules according to claim 1 or claim 5, whereby, after curing of the concrete, the surface of a weak spot therein can be reduced by at least 45% relative to a starting area of the weak spot after at least some of the microcapsules have been broken from that amount.
    [25]
    A concrete composition comprising: a cement material, one or more aggregates, a liquid binder and an amount of microcapsules according to claim 7.
    [26]
    A concrete composition according to claim 25, wherein, after curing of the concrete, the surface of a weak spot therein can be reduced by at least 45% relative to a starting surface of the weak spot after at least some of the microcapsules from that amount broken.
    [27]
    A concrete composition according to claim 24 or 26, wherein the surface of the weak spot in the concrete can be reduced by at least 50%, preferably by at least 60%, even more preferably by at least 70% and ideally by at least at least 80% relative to the initial surface of that weak spot after at least a few microcapsules have been broken from that amount.
    [28]
    A concrete composition according to any of claims 24, 26 and 27, wherein the diminutable surface area of the weak spot is determined after a continuous wet-drying cycle of 4 weeks, wherein the wet phase comprises immersion of the concrete in water for 16 hours, followed by the dry phase in which the concrete meets for 8 hours. air is exposed (at 20 ° C and a relative humidity of 60%).
    [29]
    A concrete composition according to any of claims 24 to 28, wherein the amount of microcapsules present in the composition ranges from 1 to 10, preferably 2 to 8% by weight of the cement material depending on their dry weight.
    [30]
    The concrete composition according to any of claims 24 to 29, wherein the microcapsules are added to the composition in the form of an emulsion in which the microcapsules are dispersed.
    [31]
    The concrete composition of claim 30, wherein the emulsion is a water-based emulsion.
    [32]
    A concrete composition according to any of claims 24 to 31, further comprising bacterial nutrients.
    [33]
    A concrete composition according to claim 32, wherein the bacterial nutrients are incorporated into the composition by any of the following means: by direct addition to the composition, by adding an amount of different microcapsules to the nutrients, by adding a hydrogel or another such suitable carrier, for example a porous aggregate or diatomaceous earth, containing the nutrients.
    [34]
    The concrete composition according to claim 32 or 33, wherein the amount of bacterial nutrients containing the composition ranges from 10 to 20, preferably from 12 to 18, weight percent of the cement material.
    [35]
    A concrete composition according to any of claims 24 to 34, wherein the cement material / aggregate / water / water ratio ranges from (0.5 to 1.5): (1 to 15): (0.1 to 1), preferably 1: 5: 0.5.
    [36]
    36. - Method for reducing the surface area of a weak spot in concrete, a material based on concrete and / or similar concrete material, which comprises the following phases: (i) provision of a composition of concrete, a material based on concrete and / or similar concrete material according to any of claims 24 to 35, which contains an amount of microcapsules; (ii) curing the composition; and (iii) breaking at least some of the microcapsules from that amount in response to the creation and / or aggravation of a weak spot in that cured composition, thus releasing the content of the microcapsules to reduce the weak spot to bring about.
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    同族专利:
    公开号 | 公开日
    GB201303690D0|2013-04-17|
    US20140248681A1|2014-09-04|
    US9611177B2|2017-04-04|
    US20160009596A1|2016-01-14|
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    法律状态:
    2019-12-19| MM| Lapsed because of non-payment of the annual fee|Effective date: 20190430 |
    优先权:
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    GB13036900|2013-03-01|
    GBGB1303690.0A|GB201303690D0|2013-03-01|2013-03-01|Microcapsules and contrete containing the same|
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