A pre-stressed concrete box culvert includes a three-sided culvert top section having a pre-stressed top slab, a first sidewall and a second sidewall. The first and the second sidewalls extend orthogonally from opposite ends of the pre-stressed top slab, and the first and the second sidewalls each include a free end that has at least one male or female connector. The pre-stressed concrete box culvert includes a three-sided culvert bottom section having a pre-stressed bottom slab and a third sidewall and a fourth sidewall. The third and the fourth sidewalls extend orthogonally from opposite ends of the pre-stressed bottom slab, and the third and the fourth sidewalls each include a free end that has at least one male or female connector to mate with the at least one corresponding male or female connector arranged at one of the respective free ends of the first and the second sidewalls.

A pre-stressed concrete box culvert includes a three-sided culvert top section having a pre-stressed top slab, a first sidewall and a second sidewall. The first and the second sidewalls extend orthogonally from opposite ends of the pre-stressed top slab, and the first and the second sidewalls each include a free end that has at least one male or female connector. The pre-stressed concrete box culvert includes a three-sided culvert bottom section having a pre-stressed bottom slab and a third sidewall and a fourth sidewall. The third and the fourth sidewalls extend orthogonally from opposite ends of the pre-stressed bottom slab, and the third and the fourth sidewalls each include a free end that has at least one male or female connector to mate with the at least one corresponding male or female connector arranged at one of the respective free ends of the first and the second sidewalls.

The present disclosure is related to a mold device for molding a waffle slab, wherein a plurality of connecting structures made of steel bars protrude from the sides of the waffle slab, the mold device comprising: a plurality of steel molds provided at both sides of each of the plurality of connecting structures and surrounding the waffle slab, each of the plurality of steel molds having a top surface, which has a hole therein; a plurality of auxiliary devices respectively disposed at the sides of the waffle slab and having through holes corresponding to holes in the plurality of steel molds; and a plurality of fasteners; wherein the plurality of fasteners respectively pass through the through holes of the plurality of auxiliary devices and are fixed into the holes of the plurality of steel molds so that each of the plurality of auxiliary device transversely connects the top surfaces of the plurality of steel molds.

The method according to the invention for producing a prestressed concrete workpiece is characterized in that the prestress is created by a heat treatment, wherein the concrete and the reinforcement therefor are selected in such a way that, when cooling the concrete workpiece from an elevated temperature, the heat expansion coefficient of the concrete is less than that of the reinforcement, and in that, during cooling, the concrete and the reinforcement adhere sufficiently strongly to one another if, during cooling, the concrete is hydrated at least to such an extent in order to be able to expand the reinforcement on account of the different heat expansion coefficients, and in that the concrete, together with the reinforcement, is brought to the elevated temperature in such a way that and is hydrated during cooling at least to such an extent that it is prestressed by the reinforcement after cooling.

The method according to the invention for producing a prestressed concrete workpiece is characterized in that the prestress is created by a heat treatment, wherein the concrete and the reinforcement therefor are selected in such a way that, when cooling the concrete workpiece from an elevated temperature, the heat expansion coefficient of the concrete is less than that of the reinforcement, and in that, during cooling, the concrete and the reinforcement adhere sufficiently strongly to one another if, during cooling, the concrete is hydrated at least to such an extent in order to be able to expand the reinforcement on account of the different heat expansion coefficients, and in that the concrete, together with the reinforcement, is brought to the elevated temperature in such a way that and is hydrated during cooling at least to such an extent that it is prestressed by the reinforcement after cooling.

A system and method for applying tension to a reinforcement member is provided. The system includes a gripping device, a tension device, and a tension application sub-system. The gripping device includes first and second attachments. Each attachment retains a respective end of the reinforcement member with sufficient friction force based on a predetermined tension to be applied to the reinforcement member. The tension device includes first and second tension tubes configured to removably receive and hold the first and second attachments, respectively. The tension application sub-system has first and second tension application apparatuses and first and second coupling devices. The first and second coupling devices couple the first and second tension tubes to the first and second tension application apparatuses, respectively. At least one of the first and second tension application apparatuses creates and controllably adjusts a tension load within the reinforcement member.

A process for molding prestressed slender and corrugated surface concrete bars to be used subsequently in casting concrete pieces or structures includes, placing them conveniently inside said pieces or structures, in order to also prestress said pieces or structures by gripping and relieving the tensions contained in said bar from the middle section of its longitudinal length.

A prefabricated prestressed thermal-insulated exterior wall board and a light weight composite thermal-insulated exterior wall board include a thermal-insulated core board, a reinforcement mesh on both sides of the thermal-insulated core board, and a concrete layer cast on the reinforcement mesh, and the thermal-insulated core board includes a plurality of throughout-length thermal-insulated core board ribs, and the concrete layer includes a plurality of concrete ribs interlaced with and matching the thermal-insulated core board ribs, a shear-resistant connection members connected with the reinforcement mesh is inserted between the adjacent thermal-insulated core board ribs, and prestressed tendons are disposed in grooves formed between the adjacent thermal-insulated core board ribs and grooves formed between the adjacent concrete ribs in the prefabricated prestressed thermal-insulated exterior wall board.

A prefabricated prestressed thermal-insulated exterior wall board and a light weight composite thermal-insulated exterior wall board include a thermal-insulated core board, a reinforcement mesh on both sides of the thermal-insulated core board, and a concrete layer cast on the reinforcement mesh, and the thermal-insulated core board includes a plurality of throughout-length thermal-insulated core board ribs, and the concrete layer includes a plurality of concrete ribs interlaced with and matching the thermal-insulated core board ribs, a shear-resistant connection members connected with the reinforcement mesh is inserted between the adjacent thermal-insulated core board ribs, and prestressed tendons are disposed in grooves formed between the adjacent thermal-insulated core board ribs and grooves formed between the adjacent concrete ribs in the prefabricated prestressed thermal-insulated exterior wall board.

A system and method for allowing components to attach to a pre-cast pre-stressed concrete structure is provided. The system includes a first attachment part and a second attachment part. The first attachment part has a first body. The first body has a first concrete structure facing side and a first plurality of attachment members extending from the concrete structure facing side. The second attachment part has a second body. The second body has a second concrete structure facing side and a second plurality of attachment members extending from the concrete structure facing side. The first and second attachment parts are spaced apart forming a compressible junction therebetween. The pre-cast, pre-stressed concrete structure is formed from uncured cement, at least of a portion of the first and second attachment members being embedded in the pre-cast, pre-stressed concrete structure.