A span to span duct coupler includes a coupler, a first end flange, and a second end flange. A first concrete element is formed to include a duct segment and the first end flange. The first end flange may be coupled to the first duct segment by a first duct boot. A second concrete element is formed to include a duct segment and a second end flange. The second end flange may be coupled to the second duct segment by a second duct boot. The coupler may include first and second coupler bodies and a coupler boot coupled to the first and second coupler bodies. The first coupler body may be mechanically coupled to the first end flange. The second coupler body may be coupled to the second end flange.

A span to span duct coupler includes a coupler, a first end flange, and a second end flange. A first concrete element is formed to include a duct segment and the first end flange. The first end flange may be coupled to the first duct segment by a first duct boot. A second concrete element is formed to include a duct segment and a second end flange. The second end flange may be coupled to the second duct segment by a second duct boot. The coupler may include first and second coupler bodies and a coupler boot coupled to the first and second coupler bodies. The first coupler body may be mechanically coupled to the first end flange. The second coupler body may be coupled to the second end flange.

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.

An exemplary method of indicating a condition of grout within a post-tensioned tendon involves positioning a magnet and a metallic sensing plate in close proximity to an outer surface of the post-tensioned tendon; rotating the magnet and the metallic sensing plate around the outer surface of the post-tensioned tendon; measuring an amount of magnetic forces applied to the magnet during rotation of the magnet around the post-tensioned tendon; measuring an impedance between the metallic sensing plate and metallic strands within the post-tensioned tendon during rotation of the metallic sensing plate around the post-tensioned tendon; and generating an image of a cross-section of the post-tensioned tendon indicating one or more grout conditions in spatial proximity to the metallic strands within the post-tensioned tendon based on measurement data using the magnet and the metallic sensing plate.

A variable assembly PC member includes: a plurality of hollow PC modules, each of which has an upper flange and a lower flange spaced apart from each other, and a pair of webs connecting both ends of the upper flange and the lower flange to form a hollow therein; and connectors connecting the plurality of hollow PC modules with each other in the width direction.

A duct coupler assembly includes a female duct coupler, where the female duct coupler is coupled to a first duct segment. The female duct coupler includes a female duct coupler body having an inner surface having an inner diameter and a bayonet slot formed therein. The duct coupler assembly further includes a male duct coupler. The male duct coupler is coupled to a second duct segment. The male duct coupler includes a male duct coupler body having an outer surface having an outer diameter, where the outer diameter is smaller than the inner diameter of the inner surface of the female duct coupler body. The male duct coupler has a bayonet post extending from an outer surface of the male duct coupler body, and the male duct coupler body is positioned within the female duct coupler body such that the bayonet post is positioned within the bayonet slot wherein the male duct coupler is coupled with the female duct coupler.

A duct coupler assembly includes a female duct coupler, where the female duct coupler is coupled to a first duct segment. The female duct coupler includes a female duct coupler body having an inner surface having an inner diameter and a bayonet slot formed therein. The duct coupler assembly further includes a male duct coupler. The male duct coupler is coupled to a second duct segment. The male duct coupler includes a male duct coupler body having an outer surface having an outer diameter, where the outer diameter is smaller than the inner diameter of the inner surface of the female duct coupler body. The male duct coupler has a bayonet post extending from an outer surface of the male duct coupler body, and the male duct coupler body is positioned within the female duct coupler body such that the bayonet post is positioned within the bayonet slot wherein the male duct coupler is coupled with the female duct coupler.

Segmental duct coupler devices, systems, and methods are provided herein. A duct coupler device can include a single, discrete body of material for welding to a duct segment. A system, including a duct segment having a duct coupler device welded thereto, is provided. The connection or points of connection between the duct coupler device and the duct segment in the system are devoid of internal and/or external seals. The duct coupler device and system can be cast in concrete. Multiple concrete segments can be assembled together to form a bridge, a roadway, a building, a slab, or any other structure.

Segmental duct coupler devices, systems, and methods are provided herein. A duct coupler device can include a single, discrete body of material for welding to a duct segment. A system, including a duct segment having a duct coupler device welded thereto, is provided. The connection or points of connection between the duct coupler device and the duct segment in the system are devoid of internal and/or external seals. The duct coupler device and system can be cast in concrete. Multiple concrete segments can be assembled together to form a bridge, a roadway, a building, a slab, or any other structure.

A method of constructing a reinforced concrete floor structure or wall structure, including: fabricating a precast panel substantially from concrete including a first set of parallel conduits extending through the panel, wherein the conduits open to opposite sides of the panel; moving the panel into its final position on a building site; and inserting tensioning cables through the conduits and tensioning the precast panel in the direction of the conduits to form a reinforced floor structure or wall structure, and a dowel connecting system for joining adjacent precast building panels, the system comprising elongated hollow dowel members cast in at the edges of two or more precast building panels such that when the building panels are positioned adjacent to each other their respective dowel members are co-linearly aligned; and a dowel piece to be inserted into a recess of the co-linearly aligned dowel members and to extend across the building panels, wherein the recess of the dowel members is adapted to be filled with grout to anchor the dowel piece therein and thereby structurally joining adjacent building panels.