Formwork Accessories

Formwork Accessories are a variety of independent auxiliary components matched with concrete formwork assemblies, covering tensioning, supporting, adjusting, positioning and protective parts. Each type of accessory performs separate mechanical functions, and different accessories can be combined to complete formwork fixing, load‑bearing and dimension control without modifying main formwork panels. Carbon structural steel and engineering plastic are adopted as primary raw materials. Main product categories include threaded tie rods, water‑stop tie rods, supporting screw jacks, U‑head jacks, base jacks, formwork nuts, wing nuts, positioning cones, plastic sleeves, formwork clamps, wedges and connecting pins. Tie rod series undertake tensile force to resist lateral concrete pressure and keep wall thickness dimension. Screw jack series serve as adjustable vertical supports for formwork shoring, realizing height fine‑tuning and load transmission. Nuts, clamps, wedges and connecting pins are used for splicing and locking formwork panels. Positioning cones and plastic sleeves control wall thickness, separate reusable parts and simplify post‑construction surface repair. Metal parts mostly adopt thread rolling, forging and welding processing technologies. Thread rolling improves thread tooth hardness and anti‑wear performance for repeated assembly and disassembly. Forging ensures high structural strength of nuts and locking pieces. Welding quality is critical for composite components such as water‑stop tie rods, and welding continuity shall be strictly controlled during production. Plastic accessories are formed by injection molding, featuring light weight and easy demolding.

Multiple surface anti‑corrosion treatments are available for metal formwork accessories to adapt to diverse construction environments. Hot‑dip galvanizing forms compact zinc‑iron alloy protective layers covering metal surfaces, threads and welding seams. This coating delivers stable resistance against rainwater, humid air and salt fog erosion, suitable for long‑term outdoor, underground and hydraulic‑structure construction scenarios. Electro‑galvanizing produces relatively thin zinc layer on steel surface, applicable for short‑cycle construction projects with low corrosion risk. Black oxide finish is adopted for temporary dry‑environment projects without strict anti‑corrosion requirements. Paint finishing is rarely selected for threaded parts, as paint layers tend to peel off under thread friction and concrete impact. Different main accessories bear different working loads. Tension‑type accessories mainly resist lateral pressure from fresh concrete. Support‑type accessories undertake vertical shoring loads. Locking and connecting accessories guarantee splicing rigidity between formwork panels. Reasonable matching of various accessories can effectively prevent formwork bulging, displacement and deformation during pouring.

Core dimensional parameters determine practical mechanical performance of each accessory. For tie rods and screw jacks, rod diameter is a key load‑bearing indicator, larger diameter corresponds to higher ultimate load capacity. Thread specifications of rods and nuts must be fully consistent to avoid poor meshing and slipping. The size of positioning accessories shall match designed wall thickness. Specification mismatch will lead to dimension deviation of concrete components. These accessories are widely compatible with timber formwork, steel formwork and various combined formwork systems. Dimensional tolerances shall comply with corresponding international technical specifications to guarantee reliable physical fitting during on‑site assembly.

Prior to construction deployment, visual inspection and sampling mechanical tests shall be implemented as independent inspection workflows. Visual examination covers component deformation, surface cracks, welding discontinuity, thread tooth damage and anti‑corrosion layer peeling. Recycled metal accessories require stricter inspection standards. Even with intact outward appearance, invisible metal fatigue may accumulate after repeated load cycles and cannot be judged merely through surface observation. Sampling tensile and compression tests verify ultimate bearing capacity and anti‑deformation performance. Accessories with permanent deformation, thread slipping 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 formwork accessories are prohibited. Unauthorized alteration will change original section characteristics and weaken overall mechanical performance of components.

Most metal formwork accessories are designed for cyclic reuse. After concrete curing and formwork dismantling, accessories shall be disassembled in sequence. Concrete mortar, dust and foreign residues attached to thread grooves and fitting surfaces need thorough cleaning before next installation. Impurities trapped inside thread gaps or matching surfaces will cause jamming and interfere with normal assembling and locking effect in subsequent service cycles. Finished accessories shall be stored in dry and ventilated surroundings, sorted and stacked by specification category, avoiding long‑term rain soaking and direct contact with damp soil. Improper on‑site operations include mismatching accessory specifications, insufficient tightening of locking parts, mixed use of damaged accessories, and applying load exceeding rated limit. These improper practices may trigger formwork deformation, component failure and concrete dimension deviation. As supporting auxiliary units of formwork systems, the structural integrity, specification matching degree and mechanical stability of formwork accessories directly affect overall safety of formwork assemblies and forming quality of concrete members, and constitute essential preconditions for concrete construction operations.