Bridge construction multi-strand post-tensioning

Post-tensioning is a method of reinforcing (strengthening) concrete or other materials with high-strength steel multi-strands or bars, typically referred to as tendons.

The multi-strand system is characterized by standard tendon units using either 13mm (0.5") or 15mm (0.6") diameter strands, round corrugated ducts (steel or plastic) and a selection of anchorages. Bonded and unbonded tendons are available. For the unbonded tendons, the strands are run through our specialist greasing and sheathing machine. This machine parts the individual wires of the strands followed by immersion into a grease bath before completely encapsulating the strand in the outer sheathing to ensure no voids are present.

Simultaneous stressing of all strands in a tendon is undertaken using a centre hole jack and secured using wedge grips. The free space inside the corrugated duct is pressure filled using a cementitous grout.

A range of bar diameters is available for the bar system that vary from 26mm to 75mm diameter and these can either be continuously or partially threaded. Stressing is undertaken using a centre hole jack, and a steel bearing plate and locking nut is used to anchor the end of the bar. Threaded couplings can be used to join the bars.

The applications include office and apartment buildings, parking structures, slabs-on-ground, suspended slabs, bridges, piers & piles, sports stadiums, rock and soil anchors, and water-tanks. We are able to offer a full service for this specialist trade with local experience in bridges (longitudinal and transverse), reservoirs, sports stadium, slabs on grade and ground anchors.

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