Construction Tie Rod System

Construction Tie Rod System is a complete set of matched formwork fastening assemblies widely used in cast‑in‑place concrete construction. The system is composed of main tension rods, fastening nuts, positioning cones, plastic sleeves, water‑stop plates and other matching auxiliary parts. Each component performs independent mechanical functions, and all parts cooperate with each other to realize formwork tensioning, wall‑thickness positioning and waterproof sealing without changing main formwork panels. High‑strength carbon steel and engineering plastics are adopted as main raw materials. According to application scenarios, the system can be divided into ordinary tie rod system and waterproof tie rod system. The ordinary system is applied for common non‑waterproof wall structures. The waterproof system is equipped with welded water‑stop plates on the middle embedded rod to block capillary water seepage through wall penetration points. Tie rods are available in integral one‑piece type and segmented assembled type. Integral tie rods are embedded in concrete for one‑time use. Assembled tie rods contain permanent embedded middle sections and detachable outer threaded segments, and outer segments can be disassembled and recycled after concrete hardening. Thread sections are processed by thread rolling technology to improve thread‑tooth hardness and wear resistance for repeated disassembly and assembly. Fastening nuts are produced by forging process to guarantee stable clamping force under lateral pressure of fresh concrete. Positioning cones and plastic sleeves control wall‑thickness dimension accurately and reduce later surface repair workload of concrete walls. Welding quality of water‑stop plates shall be strictly controlled to ensure reliable waterproof performance for underground and hydraulic structures.

Multiple surface anti‑corrosion treatments are available for metal components in this system to adapt to various construction environments. Hot‑dip galvanizing forms compact zinc‑iron alloy protective layers covering rod bodies, thread teeth and welding seams. This coating provides stable protection against rainwater, humid air and salt‑fog corrosion, suitable for long‑term outdoor, underground and hydraulic‑engineering projects. Electro‑galvanizing forms relatively thin zinc layers, applicable for short‑cycle construction projects with low corrosion risk. Black oxide finish is adopted for temporary dry‑condition works without high anti‑corrosion requirements. Paint finishing is rarely used on threaded components, because paint layers are easy to peel off under thread friction and concrete impact. The whole system undertakes lateral expanding force generated during concrete pouring, fixes the spacing between opposite formwork panels, restrains formwork bulging and displacement, and realizes waterproof seepage‑blocking for special waterproof structures.

Core dimensional parameters determine the overall mechanical performance of the whole system. Rod body diameter is a critical indicator of tensile‑load grade, and larger diameter corresponds to higher ultimate tensile capacity. The effective length of tie rods shall match designed wall thickness, formwork panel thickness and on‑site operating space. Thread specifications of rods and nuts must be fully consistent to avoid poor meshing, slipping and insufficient clamping force. For waterproof type, the size and welding quality of water‑stop plates shall satisfy anti‑seepage requirements under designed water head. Positioning accessories shall match the wall‑thickness dimension. Specification mismatch will cause concrete dimension deviation. This system is compatible with timber formwork, steel formwork and various combined formwork assemblies. Dimensional tolerances of all components shall comply with corresponding international technical specifications to guarantee reliable matching and coordinated stress bearing during on‑site assembly.

Prior to construction deployment, visual inspection and sampling mechanical tests shall be implemented for the whole system. Visual examination covers rod deformation, surface cracks, welding discontinuity, thread‑tooth damage and anti‑corrosion‑layer peeling. Recycled outer threaded segments need stricter inspection criteria. Even with intact outward appearance, invisible metal fatigue may accumulate after repeated load cycles and cannot be judged merely by surface observation. Sampling tensile tests verify ultimate bearing capacity and anti‑deformation performance of assemblies. Components with permanent bending, thread slipping, incomplete welding and structural cracks must be screened out and scrapped, and shall not be mixed into construction usage. Secondary modification operations including cutting, welding and hole‑drilling on finished system components are prohibited. Unauthorized alteration will change original steel‑section characteristics and weaken tensile performance or waterproof reliability of the whole set.

Part of components in Construction Tie Rod System support cyclic reuse. After concrete curing and formwork dismantling, detachable outer threaded segments, reusable nuts and positioning accessories can be disassembled in sequence. Concrete mortar, dust and foreign residues attached to thread grooves and fitting surfaces shall be thoroughly cleaned before next installation. Impurities trapped in matching positions will cause jamming and affect assembling and clamping effect in subsequent service cycles. Finished components shall be stored in dry and ventilated surroundings, sorted and stacked by specification, avoiding long‑term rain soaking and direct contact with damp soil. Improper on‑site operations include mixed use of accessories with mismatched specifications, insufficient tightening of nuts, adoption of damaged parts and over‑limit load application. These misoperations may trigger formwork bulging, component fracture, concrete dimension deviation or wall‑body water seepage. As a complete tension‑fastening solution for formwork engineering, the matching degree, welding quality and mechanical stability of Construction Tie Rod System directly determine formwork safety, concrete forming quality and long‑term anti‑leakage performance of wall structures, and constitute essential preconditions for cast‑in‑place concrete construction.