A concrete product comprising an adaptive prestressing system includes a concrete body and a composite wire embedded within the concrete body at a predetermined location. The composite wire comprises anchored end portions, each of which comprises a bonded wire segment constrained within the concrete body to resist axial motion, and an activable central portion between the end portions. The activable central portion comprises a shape memory alloy (SMA) wire segment and is axially movable within the concrete body. When heated at or above an austenite transformation temperature, the SMA wire segment contracts and the activable central portion exerts a tensile force on the end portions, thereby applying a compressive prestress within the concrete body at the predetermined location.

A pre-stressed concrete pipe is made by casting a concrete pipe inside a metal cylinder and then being pre-stressed by injecting solidifying compound under pressure into the boundary between the metal cylinder and concrete pipe, and includes a pair of end rings within the metal cylinder, each having a metal ring with an annular groove and an elastic band having a curved end to provide a rounded corner on the concrete pipe. After the solidifying compound is solidified, the concrete pipe retains the compression increasing its strength to withstand pressure, and moments caused by external loads. The pre-stressed concrete pipe further includes a bell ring mounted at one end and a spigot ring having a gasket ring at the other end. A bell clamp is mounted on the bell ring.

The invention relates to a geopolymer grout for protecting prestressing reinforcements, the geopolymer grout comprising metakaolin, fly ash and an activator mixture, the activator mixture comprising sodium hydroxide and sodium silicate, wherein the molar ratio Na.sub.2O:SiO.sub.2 of the sodium silicate is between 0.40 and 0.70.

A self-stressing shape memory alloy (SMA)/fiber reinforced polymer (FRP) composite patch is disclosed that can be used to repair cracked steel members or other civil infrastructures. Prestressed carbon FRP (CFRP) patches have emerged as a promising alternative to traditional methods of repair. However, prestressing these patches typically requires heavy and complex fixtures, which is impractical in many applications. This disclosure describes a new approach in which the prestressing force is applied by restraining the shape memory effect of nickel titanium niobium alloy (NiTiNb) SMA wires. The wires are subsequently embedded in an FRP overlay patch. This method overcomes the practical challenges associated with conventional prestressing.

Disclosed invention comprises innovations in the fabrication process and the associated design methodology for producing refined prestressed concrete elements/components. The innovations disclosed are fabrication using multiple stages, the use of ultra high strength materials for only critical subcomponents, utilizing thinner sections made of ultra high strength materials, and a unique method of inducing and controlling camber. The embodiments of this invention enable the accelerated construction of concrete structures that are both durable and cost effective. This disclosure demonstrates the significant improvements to the prior art in the areas of durability, constructability, and cost reduction for prestressed concrete components. The embodiments presented in this disclosure are for bridge superstructure applications.

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.

Disclosed invention comprises innovations in the fabrication process and the associated design methodology for producing refined prestressed concrete elements/components. The innovations disclosed are fabrication using multiple stages, the use of ultra high strength materials for only critical subcomponents, utilizing thinner sections made of ultra high strength materials, and a unique method of inducing and controlling camber. The embodiments of this invention enable the accelerated construction of concrete structures that are both durable and cost effective. This disclosure demonstrates the significant improvements to the prior art in the areas of durability, constructability, and cost reduction for prestressed concrete components. The embodiments presented in this disclosure are for bridge superstructure applications.

In a method for producing a plurality of concrete cast elements of prestressed concrete, in particular for producing of railway sleepers, in a long bed which is a multiple of the length of a concrete cast element, in which separating elements are installed in the long bed to define the length of each of the concrete cast elements to be casted, a first and a second separating element for defining the length of a concrete cast element together with a tensioning device with tensioning elements for tensioning the concrete cast element between the two separating elements are mounted in the long bed, whereupon the concrete cast element is cast between the two separating elements and is at least partially hardened in the long bed.

Disclosed invention comprises innovations in the fabrication process and the associated design methodology for producing refined prestressed concrete elements/components. The innovations disclosed are fabrication using multiple stages, the use of ultra high strength materials for only critical subcomponents, utilizing thinner sections made of ultra high strength materials, and a unique method of inducing and controlling camber. The embodiments of this invention enable the accelerated construction of concrete structures that are both durable and cost effective. This disclosure demonstrates the significant improvements to the prior art in the areas of durability, constructability, and cost reduction for prestressed concrete components. The embodiments presented in this disclosure are for bridge superstructure applications.

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.