Post Tensioning

Bonded post tensioning is a procedure used to reinforce (strengthen) concrete with high strength steel bars, typically referred to as tendons. In this concrete is cast around plastic, steel, or aluminum curved ducts in the area where tension would occur. A set of tendons are passed through the ducts and the concrete is poured in. Once the concrete hardens, the tendons are tensioned by the hydraulic jacks against the concrete itself. When the tendons are stretched sufficiently, as per the design specifications, they are wedged in position to maintain tensions after the jacks are removed, transferring pressure to the concrete.

Benefits of Bonded Post Tensioning over Unbounded Post Tensioning

• Substantial reduction in accustomed reinforcement requirements as tendons cannot distress in pileup.
• Tendons can be effortlessly “woven” allowing a more competent design approach
• No long term maintenance issues with the integrity of the anchor / dead end
• Improves the structural performance of concrete members by reducing tensile stress in the outer concrete fibers
• A sophisticated yet adaptable and versatile engineering technique
• Higher ultimate strength due to bond generated between the strands and concrete

Benefits of Post Tensioned Slabs over Conventional Slabs

Flexibility

Internal layout flexibility is greatly increased, making it much easier to place or reposition partitions.

Time saving

Framework stripping and fewer reinforcing elements results in rapid construction than R.C.C. Construction.

Economical

Reduced footing thickness, fewer support columns, lighter structures and thinner slabs resulting in less material costs and reduction in excavation and maintenance cost.

Sturdy

Increased crack resistance under load, temperature variations and concrete shrinkage due to highly compressive characteristics of prestressed concrete structure.

Better water tightness

Increase in water seepage due to flatter surface and limited deflection in the concrete structure

Multi-strand post tensioning is extensively used in construction of bridges, transportation structures and is also successfully applied for commercial building constructions.The KGN multi-strand system is symbolized by standardized tendons units of up to fifty five 13-mm (0.5)” or 15-mm (0.6)” diameter strands with a wide selections of anchorage types. Ducts are either steel or plastic and are fully bonded with cement or other high-performance grout.

Manufacturing is done on site or in factory to determine tendon lengths in advance. Simultaneous stressing of all strands is done with individual locking of each strand at the anchorage point. Stressing is carried out in number of phases with simple and reliable equipment for installation, stressing and grouting.Additionally, as the strands are stressed simultaneously, less labour is required ultimately resulting in cost savings.

Design advantages of multi-strand post tensioning systems in large structures include

• Increased span lengths
• Higher load-carrying capacity
• Reduced deflection

Benefits of KGN’s bonded slab post tensioning include:

• Enhanced control over cracks and deflections
• Reduction of mild reinforcing steel minimizes the primary sources of corrosion and significantly reduces life cycle maintenance costs.
• KGN supports thin post tensioning slab design - reducing overall building height which lowers costs for foundations, frames as well as facade/cladding components.
• As bonded tendons can be cut with only localized loss of capacity, KGN system successfully facilitates future building modifications.

This custom of KGN’s bonded post tensioning slab system has been adopted in many prestigious buildings. This approach is more economical than other systems, especially in fast construction cycles. The less material handling on site and a reduced labour force minimizes site congestions. Most importantly, KGN s specialized and highly efficient teams believe in providing high quality service to its clients

The KGN’s post tensioning system is extensively channelized in the construction of slabs on grade.We adopt a versatile method to produce slabs in commercial and industrial structures by using the principles of post tensioning to compensate excessive tensile stress.

Eliminate Joints

Joints that are reinforced concrete slabs have long been a reason for costs and delays because of the constant maintenance. The KGN post–tensioning concrete slab on grade is thinner as compared to traditionally reinforced slabs.It saves construction time and cost, because smaller amounts of concrete are laid in larger areas per day, often round about 2,500 square meters.

Supports any load

The KGN’s post-tensioning slab on grade can be designed and constructed to accommodate any load requirement.

The joint free post-tensioning slab on grade technology is used mainly in high load structures like industrial floors and pavements, storage buildings, logistic parks, etc.

Crack control

Post-tensioning slab on grade effectively reduces the risk of cracks than reinforced slabs because of the compressive forces that are applied by the post tensioning cables.

Fast-track construction

Post-tensioning slabs can be constructed much faster than conventional reinforced slabs. Time is also saved by using fewer joints and narrower footings with less excavation and less concrete.

Reduced maintenance

The use of fewer - or even no – joints significantly reduces the need for future maintenance. Studies have shown that the major costs over the life of a structure involve joint maintenance. With a post-tensioning slab, the costs of joint and crack repair are reduced as too is the damage to plant caused by the breakdown of joints.

Flexible slabs

Thinner slab isgenerally more flexible. Large overload on the slab may cause cracking;however thin pre-stressedslab returns to its previous state when the load is removed. In contrast, with a conventional reinforced slab a weak point remains in the substructure, leading to deterioration.

Flatter slabs

Fewer joints and greater spacing between them greatly reduces the risk of slab curling.

Deflection control

Soil expands when wet and shrinks when dry. This can cause movements and cracking in the foundation structure. post tensioning increases the slab’s tensile capacities, making it more resistant to problematic soils.