Construction of Roof Slab Concrete_Techniques of Reinforcement Rcc Concrete on Roof | Roof Concrete

Great — slab casting work (also known as roof slab casting or concrete slab casting) is a key part of building construction. Here's a complete overview of the process, materials, manpower, and precautions involved.

🔨 SLAB CASTING WORK – COMPLETE GUIDE

✅ 1. Preparation Work

Before casting starts:

a. Formwork (Shuttering)

Ensure all formwork is level, clean, and tight (to avoid leakage).

Use steel or plywood shuttering with proper support using props, jacks, etc.

Apply shuttering oil to allow easy removal later.

b. Reinforcement Work

Place rebars (as per structural drawing) – main bars, distribution bars, crank bars.

Maintain correct spacing and lap lengths.

Use spacers and cover blocks to maintain cover (15–25 mm typically).

Tie bars properly with binding wire.

c. Conduit Work (Electrical/Plumbing)

Lay electrical conduits and plumbing pipes (if any) within the slab.

✅ 2. Material Checklist

Cement (OPC or PPC)

Coarse aggregate (20 mm or 10 mm graded)

Fine aggregate (river sand or M-sand)

Water (clean and potable)

Admixtures (plasticizers, retarders – optional)

Concrete mix: Usually M20, M25, or M30, as per structural design

✅ 3. Concrete Pouring (Casting)

a. Concrete Mixing

Machine mix or ready-mix concrete (RMC) is preferred.

Ensure proper water-cement ratio (too much water = weak concrete).

b. Placement

Pour concrete in layers.

Use vibrators to compact the concrete and remove air pockets.

Do not allow cold joints (pour continuously).

c. Leveling & Finishing

Level the surface with straight edges.

Finish using trowel or float as needed.

✅ 4. Curing

Initial curing: Keep slab covered with wet hessian or plastic sheets for 24 hours.

Final curing: Start water curing after 24 hours, continue for at least 7–14 days.

✅ 5. De-shuttering Time

Slab bottom: 14 days (typical)

Props under beam: 14–21 days
(Follow IS codes or structural engineer’s guidance)

👷 Manpower & Equipment

Supervisor

Masons

Laborers

Vibrator operator

Mixer or RMC truck

Concrete pump (for large slabs)

Safety officer (recommended)

⚠️ Safety Precautions

All workers should wear helmets, gloves, boots.

Edge protection with guardrails or safety net.

Cordon off the casting area.

Electrical safety near vibrators and mixers.

📝 Daily Checklist (for Site Engineer)

Reinforcement as per drawing?

Electrical/plumbing embedded?

Formwork level & tight?

Vibrators working?

Concrete slump test done?

Curing arrangements ready?


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