"Don’t Pour Your Slab Until You Read This – Centering & Bar Binding"
🔷 What is Slab Centering?
Slab Centering, also known as slab formwork, is the temporary structural
arrangement provided to support wet concrete during the casting process. It
defines the shape, level, and quality of the slab and directly impacts the
structural safety and finish of the RCC work.
🔧 Key Components:
- Adjustable Props / Telescopic Spans: For
vertical load transfer
- Bottom Plates / MS Shuttering Sheets / Plywood:
Form the soffit of the slab
- Shuttering Oil: Prevents sticking of concrete
for easy de-shuttering
- Tight Jointing & Leak-Proof Sealing:
Avoids honeycombing & grout loss
✅ Quality Checklist:
- Level accuracy checked with spirit level or
laser.
- Proper spacing between props and spans as per
slab thickness.
- Camber of 1:300 provided for spans above 4m.
- Ensure no bulging, sagging or deflection in
shuttering before concreting.
🔷 What is Bar Bending / Steel Fixing?
Reinforcement is the soul
of RCC slabs. Bar bending involves cutting, bending, hooking, and placing steel
bars as per the structural drawings. Proper fixing of rebars ensures that the
concrete element can resist tensile, shear and torsional forces.
📐 Technical Detailing:
- Main Reinforcement (Bottom Layer): Placed
along the longer span to resist tension.
- Distribution Bars (Top Layer): Laid
perpendicular to main bars, controls cracking.
- Cover Blocks: Ensure minimum 20 mm cover in
slabs, as per IS 456:2000.
- Chairs: Support double-layer reinforcement
cages and maintain spacing.
- Lapping: Must be staggered and as per IS code
(usually 50d in tension zone).
- BBS (Bar Bending Schedule): Must be strictly
followed for cutting & bending accuracy.
❗Site Mistakes to Avoid:
- Missing hooks and crank bars at supports
- No cover blocks at corners and midspan
- Poorly tied bars or incorrect overlaps
- Rusted steel or placement over dusty
shuttering
⚠️ Safety Measures During Centering & Bar Work:
- All workers must use helmet, gloves, boots,
safety harness if required.
- Sharp ends of steel must be bent inward or
protected to avoid injury.
- Shuttering checks must be conducted daily
before concrete pour.
🔍 Engineer’s Tip:
🧠 “90% of slab failures
are due to negligence in centering level and steel placement. Never pour
concrete without site engineer approval.”
Comments
Post a Comment