Unbonded PC Strand

Firmstone (Tianjin) International Limited is one of the leading manufacturers and suppliers of unbonded pc strand in China. We are committed to providing high quality customized products for global clients. If you're going to buy durable unbonded pc strand made in China, welcome to get pricelist from our factory.

Unbonded PC strand – for post-tensioned concrete construction. Three-layer protection: anti-rust grease coating plus seamless HDPE sheath. Strand slides freely inside sheath, no bonding with concrete, simplifying tensioning, allowing flexible adjustment and easy maintenance/inspection. Stable low-relaxation performance, long-term corrosion resistance, ideal for long-span and thin-slab structures.

This unbonded PC strand follows unified industry standard dimensions, with a matching diameter range of 9.53mm to 17.8mm, consistent with conventional standard PC strands for strong compatibility. The HDPE protective sheath wall thickness is controlled at 1.0mm to 2.0mm to balance structural protection and fitting performance. The standard grease filling amount is no less than 50g per meter, ensuring full coverage and continuous lubrication protection. The whole product belongs to the low-relaxation grade, maintaining stable stress output and avoiding long-term structural stress loss.

The product adopts high-standard layered configuration with strictly selected industrial materials. The inner core is a mature 7-wire high-strength PC steel strand with stable tensile performance and low relaxation characteristics, providing reliable structural bearing capacity. The middle protective layer is filled with professional special anti-rust lubricating grease, which offers excellent lubrication, rust prevention and friction reduction effects, ensuring free sliding of the steel core and long-term metal protection. The outer layer adopts high-density polyethylene (HDPE) sheath material, featuring high toughness, crack resistance, waterproof performance and outdoor aging resistance, effectively isolating external moisture and corrosive substances.

Thanks to its flexible construction, easy maintenance and stable prestress performance, the unbonded PC strand is widely used in modern large-span and light-weight concrete structures. The main application scenarios include unbonded prestressing construction for high-rise building floors, large-span parking lot floor slabs, stadium and gymnasium roof structures, as well as municipal overpass slab engineering, effectively reducing floor thickness and improving structural span capacity.

The product adopts continuous integrated automated production technology to ensure stable quality: firstly, produce qualified standard high-strength PC steel strand as the inner core; secondly, conduct continuous online uniform grease filling to fully cover the strand surface without dead angles; thirdly, perform one-time extrusion molding of HDPE protective sheath outside the grease layer for tight fitting; fourthly, seal both ends of the finished strand to effectively prevent internal grease leakage and external moisture intrusion; finally, complete precise length cutting, standardized bundling and firm pallet shipment.

During transportation and stacking, avoid severe extrusion, bending and sharp object scratching to prevent HDPE sheath damage and grease leakage. On-site construction shall avoid high-temperature baking and long-term sunlight exposure before installation to protect sheath toughness. Tensioning operations must comply with prestress engineering specifications to ensure uniform stress. Damaged sheaths should be repaired in time to prevent concrete mortar penetration that may cause bonding failure.

Compared with ordinary bonded PC strand, this unbonded type features free sliding performance, simpler post-tensioning construction and lower later maintenance cost, though it is more suitable for thin-slab structures rather than heavy-load bridges. Unlike PVC and PE coated binding wires, it is a professional prestress structural material with ultra-high strength and low relaxation. It complements standard PC strands, meeting the lightweight and large-span structural demands of modern municipal and high-rise buildings.

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