Highway Underpass Concreting Technique

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Concreting a Highway Underpass: Critical Steps

When pouring concrete for vehicle underpasses beneath highways, these factors ensure structural integrity:

Formwork Bracing
Double-check steel supports to handle fresh concrete pressure (avg. 2400 kg/m³). Settlement cracks form if bracing fails.

Vibration Control
Use immersion vibrators every 60cm to eliminate air pockets. Over-vibration causes aggregate segregation.

Cold Joint Prevention
Schedule pours in less than 30-minute intervals. Delays create weak planes between layers.

Expansion Joint Setup
Embed 20mm neoprene strips every 15m for thermal movement. Misalignment risks pavement buckling.

Seepage Defense

Apply PVA-based waterproofing compound behind formwork before pouring. Essential for groundwater zones.

Post-Pour Protocol

Wet-cure for 7 days minimum

Maintain 15°C-25°C with heated blankets if needed

Demold only after reaching 70% design strength (approx. 10 days)

Always install temporary jacks under the highway deck during curing. Traffic vibrations transmitted through soil can distort setting concrete.

Emergency prep: Have quick-setting cement bags ready for overhead leaks. Stop pouring immediately if formwork deflection exceeds 10mm.

Notes based on ACI 345-19 bridge standards. Adjust for local freeze-thaw cycles.