# US 9,758,968 B2 · Method for building prestressed concrete structures by means of profiles consisting of a shape-memory alloy, and structure produced using said method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,758,968 B2 - Document ID: US9758968B2 - Status: Granted - Kind: B2 - Application number: 14/783,359 - Filed: 2014-03-17 - Published: 2016-02-25 - Granted: 2017-09-12 - Earliest claimed: 2013-04-08 - Assignees: Re-Fer AG; Empa - Applicants: Re-Fer AG; Empa - Inventors: Christian Leinenbach; Masoud Motavalli; Benedikt Weber; Wookjin Lee; Rolf Brönnimann; Christoph Czaderski - Web page: https://patentgrep.com/patent/US9758968B2 ## CPC - E04C 5/08: Members specially adapted to be used in prestressed constructions {(production of reinforced objects in general B28B23/00; prestressed structures produced in situ E04G21/12)} - C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) - C22C 38/02: containing silicon - C22C 38/04: containing manganese - C22C 38/105: {containing Co and Ni} - C22C 38/14: containing titanium or zirconium - C22C 38/40: with nickel - E04B 1/16: Structures made from masses, e.g. of concrete, cast or similarly formed in situ with or without making use of additional elements, such as permanent forms, substructures to be coated with load-bearing material (E04B1/32 - E04B1/36 take precedence) - E04C 5/01: Reinforcing elements of metal, e.g. with non-structural coatings {(E04C5/08 takes precedence)} - E04C 5/07: Reinforcing elements of material other than metal, e.g. of glass, of plastics, or not exclusively made of metal (metal elements with non-structural coatings E04C5/01) - E04G 21/12: Mounting of reinforcing inserts; Prestressing (shell tubes for prestressing members E04C5/10; anchoring means E04C5/12; connections of reinforcing elements and spacers E04C5/16) - E04G 23/0218: {Increasing or restoring the load-bearing capacity of building construction elements (E04G23/0203 and E04G23/0266 take precedence)} - E04C: STRUCTURAL ELEMENTS; BUILDING MATERIALS (for bridges E01D; specially designed for insulation or other protection E04B; elements used as building aids E04G; for mining E21; for tunnels E21D; structural elements with broader range of application than for building engineering F16, particularly F16S) - C22C: ALLOYS (treatment of alloys C21D, C22F) - E04B: GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS (border constructions of opening in walls, floors or ceilings E06B1/00; {electromagnetic shielding H05K9/0001}) - E04G: SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS ## Abstract The invention relates to a method according to which a profile consisting of a shape-memory alloy is placed into concrete, or a concrete to be reinforced is roughened on the outside, then profiles (2) consisting of a shape-memory alloy are fastened to the roughened outside (9) of the structure (6) and a cementitious matrix is applied to the roughened outside (9) to cover the profiles (2). After the cementitious matrix has set, said profiles (2) produce a contraction force and thus a tension as a result of the input of heat. The mortar covering layer (16) thereby acts as a reinforcement layer owing to the interlocking of the mortar covering layer (16) with the roughened outside (9) of the structure (6). The profiles (2) run in an outer mortar as a reinforcement layer (16) of the outside of a structure along the outside of the structure inside the mortar or reinforcement layer (16). A structure can also be prepared for a prestress in the equipped mortar or reinforcement layer by the input of heat, in that electrical cables (3) are routed from the end regions thereof to the outside of the mortar or reinforcement layer (16) or the end regions of the electrical cables (3) are accessible by removing inserts (5). ## Claims ### Claim 1 A method to create prestressed concrete structures by means of profiles made from a shape-memory alloy, be it on an outside of a new or existing concrete structure, characterised by the fact that a. the outside of the structure to be reinforced or a recess (FIG. 9) in the outside is roughened, b. profiles (2) made from a steel-based shape-memory alloy of polymorphic and polycrystalline structure with a ribbed or thread-shaped surface, which can be taken from a temporary condition as martensite to a permanent condition as austenite by increasing the temperature of the profiles (2), are attached to the roughened outside (9), c. capillary saturation of the outside with water is generated and a cementitious matrix is applied to the roughened outside as mortar mix to cover the profiles (2), d. following hardening of the cementitious matrix into a mortar matrix layer, the profiles (2) are made to generate a contraction force and thus tension through input of heat, as a result of which the mortar mix layer is prestressed as a reinforcement layer (16,19), whereby the contraction force is transmitted to the concrete or mortar mix (1) through the ribbed or thread-shaped surface of the profile (2), through the mortar matrix layer, and to the roughened outside. ### Claim 2 (depends on 1) A method to create prestressed concrete structures by means of profiles made from a shape-memory alloy according to claim 1, characterised by the fact that in step a, the profiles (2) are attached to the roughened outside (9) of the structure (6,12) with additional end anchors and in step d, force is also transmitted to the mortar mix (1) through the additional end anchors. ### Claim 3 (depends on 1) A method to create prestressed structures by means of profiles made from a shape-memory alloy according to claim 1, characterised by the fact that in step a, the outside of the structure to be reinforced (6,12) or the recess (FIG. 9) in the outside is roughened hydromechanically with a pressure of at least 500 bar or by means of sand blasting up to a surface roughness of minimum 3 mm so that a top layer of the outside forming an underground is saturated with water, in step b, the profiles (2) are attached to the roughened outside (9) by means of anchors or steel profiles, in step c, the cementitious matrix as the mortar mix is applied to the roughened outside by hand, by spraying as dry sprayed concrete, or by applying coats of self-levelling flow mortar when the roughened outside is horizontal. ### Claim 4 (depends on 1) A method to create prestressed concrete structures by means of profiles made from a shape-memory alloy according to claim 1, characterised by the fact that the profiles (2), for the purpose of heat input from a voltage source in the form of an energy unit from a row of serially linked batteries through fixed or temporarily connected electrical cables (3), are put under an electrical potential of 10-20 V per m of profile length to generate a current of 10-20 A per mm2 of cross-section area for resistance heating and are brought from the temporary condition as martensite to the permanent condition as austenite within 2 to 10 seconds. ### Claim 5 (depends on 4) A method to create prestressed concrete structures by means of profiles made from a shape-memory alloy according to claim 4, characterised by the fact that multiple electrical connections with outward leading heating cables are provided across the length of the profile and the input of heat is generated step by step through application of voltage at two neighbouring electrical connections at any one time. ### Claim 6 (depends on 1) A concrete structure built by using the method according to claim 1. ### Claim 7 (depends on 2) A concrete structure built by using the method according to claim 2. ### Claim 8 (depends on 3) A concrete structure built by using the method according to claim 3. ### Claim 9 (depends on 4) A concrete structure built by using the method according to claim 4. ### Claim 10 (depends on 5) A concrete structure built by using the method according to claim 5. ### Claim 11 (depends on 2) A method to create prestressed structures by means of profiles made from a shape-memory alloy according to claim 2, characterised by the fact that in step a, the outside of the structure to be reinforced (6,12) or the recess (FIG. 9) in the outside is roughened hydromechanically with a pressure of at least 500 bar or by means of sand blasting up to a surface roughness of minimum 3 mm so that a top layer of the outside forming an underground is saturated with water, in step b, the profiles (2) are attached to the roughened outside (9) by means of anchors or steel profiles, in step c, the cementitious matrix as the mortar mix is applied to the roughened outside by hand, by spraying as dry sprayed concrete, or by applying coats of self-levelling flow mortar when the roughened outside is horizontal. ### Claim 12 (depends on 2) A method to create prestressed concrete structures by means of profiles made from a shape-memory alloy according to claim 2, characterised by the fact that the profiles (2), for the purpose of heat input from a voltage source in the form of an energy unit from a row of serially linked batteries through fixed or temporarily connected electrical cables (3), are put under an electrical potential of 10-20 V per m of profile length to generate a current of 10-20 A per mm2 of cross-section area for resistance heating and are brought from the temporary condition as martensite to the permanent condition as austenite within 2 to 10 seconds. ### Claim 13 (depends on 3) A method to create prestressed concrete structures by means of profiles made from a shape-memory alloy according to claim 3, characterised by the fact that the profiles (2), for the purpose of heat input from a voltage source in the form of an energy unit from a row of serially linked batteries through fixed or temporarily connected electrical cables (3), are put under an electrical potential of 10-20 V per m of profile length to generate a current of 10-20 A per mm2 of cross-section area for resistance heating and are brought from the temporary condition as martensite to the permanent condition as austenite within 2 to 10 seconds. ### Claim 14 (depends on 11) A concrete structure built by using the method according to claim 11. ### Claim 15 (depends on 12) A concrete structure built by using the method according to claim 12. ### Claim 16 (depends on 13) A concrete structure built by using the method according to claim 13. ### Claim 17 (depends on 1) A method to create prestressed structures by means of profiles made from a shape-memory alloy according to claim 1, characterised by the fact that in step d, after the hardening of the applied mortar mix into the mortar matrix layer and before the input of heat, the mortar mix layer (16,19) is dowelled by applying dowels (13) which extend behind a front concrete reinforcement (7,8) of the structure (12) behind the mortar mix layer (16,19). ### Claim 18 A method to create prestressed structures on an outside of a new or existing concrete structure, the method comprising: roughening the outside; attaching a profile to the roughened outside, the profile being made from a shape-memory alloy having an elongated state and a shortened state, the attached profile being in the elongated state; saturating the roughened outside with water; applying a cementitious matrix to the saturated roughened outside to cover the profile; allowing the cementitious matrix to harden into a mortar matrix layer; and heating the profile to transform the covered attached profile to the permanent state and stress the mortar matrix layer.