The unbonded prestressed steel strand is formed by coating the surface of the prestressed steel strand with anti-corrosion and lubrication coating and wrapping it with high-density polyethylene sheath. The steel strand and the sheath can slide permanently.

Its advantage is that it does not need to reserve holes, thread reinforcement, grouting and other complex processes during construction, the construction procedure is simple, and the construction speed is accelerated. At the same time, the friction force is small and it is easy to bend into multi span curve type, which is especially suitable for large span single and two-way continuous multi span curve reinforced beam slab structure and roof.