Strand post-tensioning systems
BBV Systems holds technical approvals for internal and external post-tensioning (PT) systems. We have the required qualification for the installation of these systems. With the adoption of the ETAG 013 (Guideline for the European Technical Approval of post-tensioning kits for prestressing of structures) in June 2002, the required scope of testing for post-tensioning systems was re-established in Europe. According to these test guidelines our systems are approved both nationally and Europe-wide.
Internal bonded post-tensioning
The internal bonded PT system has been designed for the use of seven-wire strands with grade Y1860, having a nominal cross-sectional area of 140 mm² or 150 mm². The tendons consist of 3 up to 31 strands and are either supplied to the construction site as prefabricated tendons or are produced on site. All types of tendons can be connected by fixed or movable couplers.
Our internal bonded anchors are also available as fully electrically isolated anchors, tested and approved according to the Swiss standard SIA 262/1, corrosion protection category c.
Internal unbonded post-tensioning
The internal unbonded PT system consists of one or several cast-in monostrands, which are stressed after the concrete has reached the required strength. Each strand is individually sheathed in polyethylene, the space between the PE-coat and the steel strand is filled with anti-corrosive material (grease). As this system does not work with ducts requiring grouting works, smallest tendon diameters can be realized, making the system ideal for thin structures as flat slabs, bridge decks, silos and towers.
The external PT system provides tendons, which are located inside the height of the structure, but outside of the concrete cross section. The BBV system type EMR works with monostrands, which are bundled in a common outer duct, serving as mechanical protection.
BBV’s system type E consists of bare strands in a common outer duct. After installation of the strands into the duct, the tendon is injected with heated corrosion protection mass.
Both external systems allow for tendon inspection, restressing and replacement of tendons.