Code of Practice for Curing of Cement Concrete Pavements

IRC 84: Introduction - Key Specifications & Guidelines

1. Hot Air/Steam Curing Enclosure (Fig. I)

• Frame stands (A): Trapezoidal, angle iron or wood, spaced 4.5-5 m.
• Fixing members (B): Angle iron or wood to stabilize stands.
• Inlet pipe (C): For steam/hot air/water.
• Distributor pipe (D) and Perforated discharge pipes (E): Spaced 4.5-5 m for uniform distribution.
• Covering (tarpaulins) forms enclosure (not shown in figure).

2. Mortar Test Slab (Clause 1.71)

• Mix ratio: 1 part cement : 1.71 parts fine aggregate : 0.346 parts water (by weight).
• Size: 400 mm × 400 mm × 50 mm.
• Cast in watertight mould, coating applied within 2 hours.

3. Curing Period & Method

• Minimum curing: 28 days.
• Hot weather: Cover concrete with wet hessian/gunny bags or cure at night.
• Cold weather: No concreting below 4℃ (without authorization).
• Maintain concrete temperature during placement: 10℃ to 32℃.
• Use insulating material and steam/warm air circulation for cold curing.

4. Important Notes

• Avoid slippery surfaces after membrane curing.
• Solid membrane curing not permitted; liquid membranes allowed if water is scarce.

Summary Table: Temperature Limits for Concreting

flowchart LR
    A[Frame Stands (4.5-5 m spacing)] --> B[Fixing Members]
    B --> C[Inlet Pipe (Steam/Hot Air/Water)]
    C --> D[Distributor Pipe]
    D --> E[Perforated Discharge Pipes (4.

IRC 84: General Principles of Curing for Cement Concrete Pavements

1. Conventional Curing (Ponding Method)

• Pond size: ~1.5 m × 1.5 m × 5 cm depth
• Bunds: Equilateral triangular cross-section, base & height ≈ 50 mm, made of 1:12 to 1:15 cement-sand mortar
• Water depth: 20-30 mm after 6-8 hours of bund formation
• Duration: Minimum 14 days from initial curing start
• Maintenance: Keep ponds wet, remove bunds & clean joints after curing

2. Membrane Curing

• Used where water is scarce or slopes prevent ponding
• Types:
  • Solid membranes: Transparent polyethylene sheets (≥400 gauge) or bituminized waterproof papers reinforced with fiber mesh
  • Liquid membranes: Silicones, wax emulsions (25-50% diluted), linseed oil, sodium silicate solution, etc.
• Duration: Continue membrane curing up to 28 days from initial curing
• Application: Liquid membranes sprayed uniformly within 0.5 hour of finishing; must harden within 30 minutes
• Performance: Should retain ≥90% mixing water for 72 hours at 35-38°C and 30-35% RH

Summary Table

flowchart LR
    A[Start Initial Curing] --> B{Water Available?}
    B -->|Yes| C[Ponding Method]
    B -->|No| D{Slope Suitable?}
    D -->|Yes| E[Membrane Curing]
    D -->|No| C
    E --> F{Solid

Conventional Method of Curing (IRC 84)

Initial Curing:

• Use damp hessian cloth, burlap, or gunny bags for the first 24 hours.
• Cloth width: ~1 m; overlap joints by 150 mm (gunny bags 75-100 mm).
• Cover entire slab surface and edges extending 500 mm beyond slab edges.
• Keep matting fully wet by gentle sprinkling.
• Remove matting only if concrete is hard enough; exposure max 30 minutes.

Final Curing:

• Remove matting in parts to avoid exposure >30 minutes.
• Bank exposed slab edges with soil berms:
  • Base: 200 mm, Height: 100 mm, Top: 150 mm.
• Construct transverse and longitudinal dykes (clay bunds):
  • Height: 50 mm, Width: 150 mm, Covered with 40 mm soil blanket.
• Maintain soil wetness from day 15 to day 28.
• Remove soil, bunds, and berms after permission; clean joints and sweep pavement.

Alternative Ponding Method (for airfield pavements):

• Ponds: 1.5 m × 1.5 m × 5 cm deep.
• Bunds: equilateral triangle cross-section, base & height ~50 mm, made of 1:12 to 1:15 cement-sand mortar.
• After bunds, keep pavement wet, then fill ponds with 20-30 mm water after 6-8 hours.
• Maintain ponding for at least 14 days.

Summary Table: Bund Dimensions & Ponding

Key Points:

• Water used must be free from harmful salts (IS:456-1978).
• Maintain continuous moisture for at least 14 days (ponding) or 28 days (membrane curing).
• In water-scarce or sloped areas, use **membrane

Membrane Curing (IRC 84)

Types of Membrane Curing

• Solid Membrane: Polyethylene sheets (≥400 gauge) or bituminous waterproof papers (multi-ply, fibre-reinforced).
• Liquid Membrane: Light-colored coatings (e.g., silicone wax emulsions diluted 25-50%, linseed oil, sodium silicate solution diluted to paint consistency).

Solid Membrane Curing Specifications

• Use transparent polyethylene sheets ≥400 gauge or bituminous papers.
• Apply after initial curing (wet matting for 24 hrs).
• Continue membrane curing up to 28 days from start of initial curing.
• Remove membrane, bunds, and battens after Engineer-in-Charge approval.
• Clean joints thoroughly by raking and washing.

Liquid Membrane Curing Guidelines

• Apply within 0.5 hour of finishing or after removing initial curing mat.
• Spray uniformly under light pressure.
• The membrane should harden within 30 minutes.
• Retain ≥90% mixing water in test slabs after 72 hrs at 35-38°C, 30-35% RH.
• Supplier must provide type test certification.

Ponding Bund Dimensions (for alternative curing)

Summary Flow of Membrane Curing

flowchart TD
    A[Initial Curing: Wet Matting (24 hrs)] --> B{Water availability?}
    B -- Yes --> C[Ponding or Soil Cover Final Curing]
    B -- No --> D[Solid Membrane Curing]
    D --> E[Continue till 28 days]
    E --> F[Remove membrane & clean]
    C --> F

Note: Membrane curing is essential where water is scarce or slopes prevent ponding. Solid membranes are commonly used in India; liquid membranes are rare and require strict quality control.

Key Specifications & Precautions for Concreting at High Temperature (IRC 84)

Conditions Requiring Special Precautions:

• Air temperature > 40°C, or
• Air temperature > 35°C with:
  • Relative humidity < 25%, and/or
  • Wind velocity > 10 km/h

Precautions (Clause 5.2 & 5.3)

• Cover freshly laid concrete immediately with wet hessian cloth, burlap, or gunny bags to reduce evaporation.
• Prefer evening or night concreting to avoid peak heat.
• During noon hours (11 AM - 5 PM), cover concrete with tarpaulins on travelling stands.
• Use matting for initial curing, starting earlier than normal.
• Follow with thorough ponding curing.
• Total curing period: minimum 28 days.
• Solid membrane curing NOT permitted; liquid membranes allowed if water is scarce.

Mortar Test Slab for Impervious Coatings (Clause 4.3.5)

• Slab size: 400 mm × 400 mm × 50 mm
• Coating applied within 2 hours of casting.

Summary Diagram: High Temperature Concreting Process

flowchart TD
    A[Check Temperature & Conditions] --> B{Is Temp > 40°C or (Temp > 35°C & RH < 25% or Wind > 10 km/h)?}
    B -- Yes --> C[Apply wet hessian cloth or burlap immediately]
    C --> D[Prefer evening or night concreting]
    D --> E[Cover with tarpaulins during 11 AM - 5 PM]
    E --> F[Start early curing with matting]
    F --> G[Ponding curing for 28 days]
    B -- No --> H[Normal concreting & curing]

Note: These guidelines ensure hydration is maintained, preventing plastic shrinkage cracks and strength loss under hot weather conditions per IRC 84 and IRC 61.

Key Formulas, Tables & Specifications for Concreting at Cold Temperatures (IRC 84)

1. Temperature Limits for Concreting

2. Concrete Protection & Curing

• Initial curing: Cover concrete with tarpaulins (11 AM - 5 PM) for 24 hours post-laying.
• Total curing: Minimum 28 days; solid membrane curing prohibited.
• Subsequent curing: Thorough ponding or liquid membrane curing (if water scarce).

3. Insulation Requirements

• Maintain air around concrete at 10℃ for 3 days or 5℃ for 5 days using insulation + steam/warm air if needed.

4. Additional Notes

• Cover freshly placed concrete immediately with tarpaulin to minimize exposure.
• Use accelerators and heating equipment as per IRC:15 if concreting below 4℃ is authorized.
• No concreting if air temp < -7℃.

Summary Diagram: Cold Weather Concreting Process

flowchart TD
    A[Check Air Temperature] -->|≥4℃| B[Proceed with Normal Concreting]
    A -->|<4℃| C[Seek Engineer Authorization]
    C -->|Authorized| D[Heat Concrete to 10-32℃ & Use Accelerators]
    C -->|Not Authorized| E[Delay Concreting]
    D --> F[Place Concrete]
    F --> G[Cover with Tarpaulin Immediately]
    G --> H[Maintain Air Temp 10℃ for 3 days or 5℃ for 5 days]
    H --> I[28

Key Specifications & Procedures for Curing Airfield Pavements (IRC 84):

Initial Curing (Clause 3.2)

• Use hessian cloth/burlap (1 m wide) with:
  • Overlap: 150 mm (hessian), 75-100 mm (gunny bags).
  • Extend 500 mm beyond slab edges.
• Place matting wet side down, keep fully wet for at least 24 hours.
• Maintain matting wet using gentle water spray; remove only for <30 minutes if needed.
• Worn or reused matting must be clean and intact.
• Use wooden bridges for placing matting; no walking on fresh concrete.

Final Curing (Clause 3.3)

• Remove matting in parts; surface exposed <30 minutes.
• Build berms and dykes with local soil and clay:
  • Berm: 200 mm base, 100 mm height, 150 mm top.
  • Dykes: 50 mm high, 150 mm wide, trapezoidal bunds ~150 mm base, 100 mm height, 100 mm top.
• Cover slab with ≥40 mm soil blanket.
• Keep soil wet from day 15 to day 28.
• Remove soil and clean pavement before opening to traffic.

Alternative Final Curing for Large Airfields (Clause 3.4)

• Use ponds (1.5 m × 1.5 m × 5 cm) with cement-sand mortar bunds (base & height ~50 mm).
• Keep pavement wet during bund construction.
• Fill ponds with 20-30 mm water after 6-8 hours.
• Maintain ponds wet for minimum 14 days.
• Remove bunds by light chiselling and clean pavement before traffic.

Membrane Curing (Clause 4)

• Solid membranes: polyethylene sheets (≥400 gauge) or bituminous papers.
• Use wet matting initially; membrane curing continues up to 28 days.
• Remove membranes and clean pavement before opening.
• Liquid membranes: apply within 0.5 hours of finishing or after removing initial curing mats.
• Must retain ≥90% mixing water at 35-38°C, 30-35% RH for 72 hours.

Summary Table for Curing Dimensions

IRC 84: Materials and Methods for Curing Concrete Pavements

Key Specifications & Methods:

1. Initial Curing (Clause 3.2)

• Use hessian cloth/burlap (1 m wide rolls).
• Overlap strips by 150 mm; extend matting 500 mm beyond slab edges.
• Place wet matting with wet side down immediately after concrete sets.
• Keep matting continuously wet for at least 24 hours or until concrete hard enough to walk on.
• Remove matting only for max 30 minutes if needed.
• Worn or reclaimed matting must be clean and intact.

2. Final Curing (Clause 3.3)

• Remove initial curing matting in parts; keep surface covered.
• Bank slab edges with soil berm:
  • Base: 200 mm, Height: 100 mm, Top: 150 mm.
• Form transverse & longitudinal clay dykes:
  • Height: 50 mm, Width: 150 mm (trapezoidal bunds).
• Cover slab with ≥40 mm sandy soil blanket.
• Keep soil moist from day 15 to day 28.
• Remove soil, bunds, and clean pavement before traffic.

3. Ponding Method for Airfield Pavements (Clause 3.4)

• Construct ponds 1.5 m × 1.5 m × 5 cm with bunds (50 mm base & height).
• Keep pavement wet during bund construction.
• Fill ponds with 20-30 mm water depth after 6-8 hours.
• Maintain ponding for at least 14 days.
• Remove bunds and clean joints before opening to traffic.

4. Membrane Curing (Clause 4)

• Solid membranes:
  • Transparent polyethylene sheets, min. 400 gauge or bituminised waterproof papers reinforced with fiber mesh.
  • Use wet matting initially, solid membrane for final curing.
  • Continue membrane curing up to 28 days.
• Liquid membranes (less common):
  • Silicones, wax emulsions (25-50% diluted), linseed oil, sodium silicate (20% water diluted).
  • Apply uniformly by spray before cement sets.
  • Must retain ≥90% mixing water

IRC 84: Curing Period and Procedures - Key Points

1. Ponding Curing

• Pond size: ~1.5 m × 1.5 m × 5 cm depth
• Bunds: Equilateral triangular cross-section, base & height ~50 mm, made with 1:12 to 1:15 cement-sand mortar.
• Water depth in pond: 20-30 mm after 6-8 hours of bund formation.
• Curing duration: Minimum 14 days from start of initial curing.
• Maintenance: Keep ponds wet; remove bunds after permission to open pavement.

2. Membrane Curing

• Types: Solid membranes (preferred) and liquid membranes.
• Solid membranes: Transparent polyethylene sheets (≥400 gauge) or bituminized waterproof papers with fiber reinforcement.
• Duration: Continue curing up to 28 days.
• Liquid membranes: Apply within 0.5 hr after finishing; must retain ≥90% mixing water over 72 hrs at 35-38°C, 30-35% RH.
• Application: Spray uniformly, hardening within 30 minutes.

3. Cold Weather Concreting

• No concreting below 4°C without permission.
• Concrete temp at placement: 10°C minimum (not less than 5°C).
• Maintain surrounding air temp at 10°C for 3 days or 5°C for 5 days.
• Use insulating covers and heating as needed.

Summary Table: Curing Periods

flowchart LR
    A[Concrete Placement] --> B{Curing Method}
    B --> C[Ponding Curing]
    B --> D[Membrane Curing]
    B --> E[Cold Weather Curing]

    C --> C1[Build Bunds]

IRC 84: Special Precautions and Recommendations Summary

1. Mortar Test Slab for Impervious Coating (Clause 4.3.5)

• Mix ratio:
  • Cement : Fine Aggregate : Water = 1 : 1.71 : 0.346 (by weight)
• Slab size: 400 mm × 400 mm × 50 mm
• Cast in non-absorbent, watertight mould; coating applied within 2 hours.

2. Membrane Curing (Clause 4)

• Solid membranes:
  • Polyethylene sheets (≥400 gauge) or bituminised waterproof papers with fibre mesh.
  • Continue curing for 28 days from initial curing start.
• Liquid membranes:
  • Examples: diluted sodium silicate, silicone wax emulsions.
  • Must retain ≥90% mixing water over 72 hrs at 35-38℃, 30-35% RH.
  • Apply within 1 hour after finishing or after removing initial curing cover.

3. Hot Weather Concreting (Clause 5)

• Conditions needing precautions:
  • Air temp > 40℃ or air temp > 35℃ + RH < 25% + wind > 10 km/h.
• Measures:
  • Cover concrete with wet hessian/burlap/gunny bags ASAP.
  • Pour concrete in evening/night if possible.
  • Cover with tarpaulins from 11 AM to 5 PM for 24 hours post-laying.
  • Total curing ≥ 28 days; solid membrane curing not allowed.

4. Cold Weather Concreting (Clause 6)

• No concreting if temperature < 4℃ (descending) without written permission.
• Concrete temperature at placement: 10℃ to 32℃ (min 5℃ allowed).
• Maintain surrounding air temperature at:
  • 10℃ for 3 days or 5℃ for 5 days post-placement.
• Use insulating layers (waterproof paper + sawdust/straw 10-30 cm thick).
• No concreting below -7℃.

5. Ponding Curing (Clause 3.4.2)

• Pond size: **1.5

Key Specifications for Testing & Approval of Curing Materials (IRC 84)

1. Ponding Method (Clause 3.4.2 - 3.4.3)

• Pond size: 1.5 m × 1.5 m × 5 cm depth
• Bunds: Equilateral triangular cross-section, base & height ≈ 50 mm, made of 1:12 to 1:15 cement-sand mortar.
• Water depth in pond: 20-30 mm
• Curing duration: Minimum 14 days.
• Bund removal after Engineer's permission; clean joints thoroughly.

2. Membrane Curing (Clause 4)

• Solid membranes: Transparent polyethylene sheets (≥ 400 gauge) or bituminized waterproof papers reinforced with fiber mesh.
• Liquid membranes: Light-colored emulsions (silicone wax, linseed oil, sodium silicate diluted 20% water).
• Membrane curing duration: Up to 28 days.
• Liquid membrane application: Uniform spray within ½ hour of finishing; coating hardens within 30 minutes.
• Surface retention test: Must retain ≥ 90% mixing water over 72 hrs at 35-38°C, 30-35% RH.

3. Type Test for Liquid Membrane (Clause 4.3.5)

• Mortar slab mix:
  • Cement : Fine aggregate : Water = 1 : 1.71 : 0.346 (by weight)
• Slab size: 400 mm × 400 mm × 50 mm
• Coating applied within 2 hours of casting.
• Approval based on test results from recognized labs.

Summary Table: Curing Methods & Key Parameters

Key Specifications & Illustrations from IRC 84 (Curing of Concrete Pavements)

1. Frame & Tubing System for Hot Air/Steam Curing (Fig. I)

• Frame stands (A): Trapezoidal, angle iron or wood, spaced 4.5–5 m apart.
• Fixing members (B): Angle iron or wood to secure frame stands.
• Inlet pipe (C): For steam/hot air/water.
• Distributor pipe (D) & Perforated discharge pipes (E): Spaced 4.5–5 m for uniform distribution.
• Covering: Tarpaulins or similar to form enclosure (not shown).

2. Initial Curing

• Use hessian cloth/burlap (1 m wide rolls).
• Overlap joints by 150 mm (gunny bags 75–100 mm).
• Extend matting 500 mm beyond slab edges.
• Keep matting wet for 24 hours or until concrete can be walked on.
• Remove matting only for ≤30 minutes to avoid drying.

3. Final Curing

• Ponding water after removing initial curing matting.
• Edge berms: 200 mm base × 100 mm height × 150 mm top (soil).
• Clay dykes: 150 mm base × 100 mm height × 100 mm top.
• Soil blanket ≥ 40 mm depth after wetting.
• Maintain wetting until 28 days or as directed.

4. Airfield Pavements Alternative Final Curing

• Ponds: 1.5 m × 1.5 m × 5 cm depth.
• Bunds: Triangular cross-section, base & height ~50 mm, made from 1:12 to 1:15 cement-sand mortar.
• Keep ponds wet for minimum 14 days.

5. Membrane Curing

• Solid membranes: Polyethylene sheets (≥400 gauge) or bituminous papers.
• Liquid membranes: Silicones, wax emulsions, linseed oil, sodium silicate solutions (applied before cement sets or after initial curing matting removal).
• Continue membrane curing till 28 days.

Summary Table: Curing Dimensions & Materials

| Item | Dimension/Specification | Notes | |---------------------|