Rebar chair spacers position reinforcement steel grids and rebar meshes at predetermined clearance heights prior to concrete placement. By maintaining exact concrete cover depth, these spacers ensure total rebar encapsulation, preventing structural steel exposure, premature moisture penetration, and subsequent rebar oxidation.
Supplied across high-density polyethylene (HDPE), polypropylene (PP), cementitious concrete, and steel configurations, these components accommodate heavy rebar loads without tilting, slipping, or deflecting during concrete pouring and mechanical vibration.
Key Product Characteristics
High Load Capacity: Thick-walled rib structures prevent crushing under heavy rebar cages and site foot traffic.
Stable Footprint: Wide base plates and multi-leg configurations prevent sinking into soft insulation layers or damp soil subgrades.
Multi-Cover Heights: Dual and quad-height geometry allows one spacer model to cover multiple specified concrete cover depths (e.g., 50mm / 75mm).
Concrete Bonding: Open-frame clip-on designs and fiber-reinforced concrete blocks allow seamless slurry flow, eliminating air voids or thermal expansion mismatches.
Corrosion Resistance: Non-corrosive plastic and concrete variants eliminate rust spots on exposed outer concrete surfaces.
Key Specifications
|
Specification |
Plastic Rebar Chairs |
Heavy-Duty Concrete Chairs |
Steel Wire / Ring Chairs |
|
Material Base |
HDPE / PP (Virgin or Recycled blend) |
Fiber-reinforced concrete (C50/60) |
Cold-drawn steel wire / Epoxy-coated |
|
Cover Height Range |
15 mm - 100 mm (0.6" - 4.0") |
20 mm - 100 mm (0.8" - 4.0") |
20 mm - 300 mm (0.8" - 12.0") |
|
Compatible Rebar Bar Sizes |
#3 to #8 (8 mm - 25 mm) |
#3 to #11 (8 mm - 36 mm) |
#3 to #10 (8 mm - 32 mm) |
|
Static Load Rating |
150 kg - 350 kg per point |
300 kg - 600+ kg per point |
200 kg - 500 kg per point |
|
Thermal Deformation (HDPE) |
HDT @ 0.45 MPa: 75°C - 85°C |
N/A (Fire-rated A1) |
N/A |
|
Subgrade Compatibility |
Hard formwork, soft subbase, insulation |
Hard formwork, civil structures |
Metal deck, concrete blindings |
Grades & Standards
BS 7973-1 / BS 7973-2: Spacers and chairs for steel reinforcement (dimensioning, load capabilities, and positioning).
DBV-Code of Practice: German DBV guidelines for spacers in concrete construction (category evaluation for stability and thermal resistance).
ACI 318 / ACI 301: American Concrete Institute specifications for concrete cover tolerances and reinforcement support placement.
EN 12390 / ISO 9001: Material compressive strength compliance and factory quality control standards.
Applications
Precast Concrete Elements: Wall panels, structural beams, columns, and hollow core slabs requiring precise clear cover tolerances.
Cast-in-Place Slabs & Decks: High-rise floor slabs, bridge decks, and suspended parking structure decks.
On-Grade Foundations: Heavy raft foundations, footings, and grade beams utilizing flat-bottom spacers to prevent subgrade penetration.
Civil Engineering Projects: Tunnel linings, retaining walls, marine seawalls, and water treatment tanks subject to aggressive chemical exposure.
Installation
Selection: Choose spacer type based on substrate (e.g., flat base for soft ground/insulation; standard clips for plywood/steel formwork).
Spacing Grid: Place chairs every 0.8 m to 1.0 m (2.5 ft to 3.3 ft) along primary steel bars to prevent sagging between support points.
Engagement: Snap rebar into top clip jaws or secure loose rebar onto flat seats using integral tie-wires.
Pre-Pour Inspection: Ensure spacers are perpendicular to formwork and check that no movement occurs under localized crew foot traffic.
Quality & Inspection
Compressive Point Load Testing: Batch samples are tested under hydraulic press to verify breaking thresholds under site conditions.
Impact Testing at Low Temperatures: Plastic models undergo drop-weight tests at -5°C to verify fracture resistance in cold climates.
Dimension & Tolerance Checks: Heights are verified within +/-1.0 mm accuracy to ensure strict compliance with architectural cover depth plans.
Material Integrity: Chemical purity testing on polymer batches guarantees high UV stability and zero structural degradation when embedded.
Supply & Customization
Standard Packaging: Packed in heavy-duty woven polypropylene bags or cartons, stacked on ocean-freight pallet systems (10,000-50,000 pcs per pallet).
Custom Height & Jaw Sizes: Custom injection molds developed for non-standard bar diameters or specific infrastructure cover specifications.
Color Coding: Color adjustments available for quick jobsite identification of specific cover heights.
Material Formulations: Cold-weather impact-modified polymers or recycled material blends available upon request.
What Buyers Should Provide
To receive an accurate quote, supply the following details:
Required Cover Height: Specified concrete cover depth (e.g., 25mm, 40mm, 50mm, 75mm).
Rebar Diameter: Bar sizes to be held (e.g., #4 / 12mm bar).
Substrate Condition: Hard formwork (plywood/steel), soft ground, blinding concrete, or insulation boards.
Project Type / Industry Standard: Precast element manufacturing, civil infrastructure, or commercial slab on grade.
Estimated Volume & Port of Destination: Packaging preference (bags/cartons) and required shipping terms (FOB, CIF, DAP).
FAQ
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