Post-tensioning concrete enables Byrne Bros to utilise the entire range of allowable stresses across the section depth, creating a strong, slender and efficient element.
The slab systems for bonded post-tensioning are 12.7mm or 15.2mm in diameter seven-wire, low relaxation strands, in tendons which consist of up to five strands.
The system uses a flat galvanised duct to house the cables to achieve efficient drape within the depth of shallow concrete members.The most common uses are in transfer beams, underground and submerged structures, bridges, headstocks or tank structures.
Advantages of post-tensioning concrete:
- Controlled cracking
- High compressive strength of concrete is employed
- Reduction in depth of beams (common depth/span ratios of 1:20)
- Reduction in depth of slab (common depth/span ratios of 1:40)
- Reduction in column and foundation size
- Webs of pre-stressed beams are much thinner
- Up to 25% less dead weight than reinforced concrete
- Low self-weight of 1/5 compared to reinforced concrete
- Very economic and structurally efficient over 8m spans
- Flexibility in planning and design
- Excellent load bearing performance in ground slabs
- Controlled deflection
- Smaller quantities of reinforcement required reducing cost of materials and labour
- Standardised details using reduced lead time and labour