Guidelines for the Design and Construction of Cement Concrete Pavement for Low-Volume Roads (First Revision)

Scope of IRC SP 62 (Clause 3 - Page 3):

• Covers design, materials, construction, and quality control of rigid pavements for village roads.
• Includes specifications for slab thickness, joints, materials, and mix design.
• Addresses special concrete types like Self-Compacting Concrete (SCC) for improved productivity and quality.

Key Points on Curling Stresses (Clause 2.3)

• Curling due to temperature gradients causes internal bending moments and stresses.
• Bending Moment (Interior):
  [ M = D \cdot \alpha \cdot \Delta T \cdot (1 + \nu) ]
• Stress (Interior):
  [ \sigma = \frac{6M}{h^2} \left( \frac{1}{4} - \frac{z^2}{h^2} \right) ]
• Edge Stress:
  [ \sigma = \frac{12M}{h^2} \left( \frac{1}{4} - \frac{z^2}{h^2} \right) ]
• Parameters:
  • ( \alpha = 10^{-5} ) (thermal expansion)
  • ( E = 30000 \text{ MPa} ) (modulus of elasticity)
  • ( \nu = 0.15 ) (Poisson's ratio)
  • (\Delta T) = temperature differential

Self-Compacting Concrete (SCC) - Appendix III Highlights

• Definition: Concrete that flows and consolidates under its own weight without vibration.
• Key Properties:
  • Filling ability: fills formwork fully.
  • Passing ability: flows through reinforcement without blocking.
  • **Segregation

IRC SP 62: Key Terminology & Specifications for Concrete (Clause 4.75 & Appendix III)

• Powder Fraction: Portion of concrete comprising paste + aggregates < 4.75 mm, including cement, fly ash, silica fume, crushed sand (<0.125 mm).
• Passing Ability: Fresh concrete's capacity to flow through tight spaces (e.g., between reinforcement) without blocking/segregation.
• Self-Compacting Concrete (SCC): Concrete that flows and consolidates under its own weight, filling formwork even with dense reinforcement, without vibration.
• Segregation Resistance: Ability to maintain homogeneity in fresh state.
• Viscosity: Resistance to flow once started; measured by T500 slump flow or V-funnel efflux time.
• Viscosity Modifying Admixture (VMA): Added to increase cohesion and segregation resistance.
• Filling Ability: Ability to fill all formwork spaces under self-weight.
• Flowability: Ease of flow unconfined by formwork.

Rheological Properties Summary

SCC Mix Design Essentials

• Low water-powder ratio
• Use of superplasticizers
• VMA for viscosity control
• Mineral admixtures (fly ash, silica fume) to enhance flow and durability

flowchart LR
    A[Fresh Concrete] --> B(Passing Ability)
    A --> C(Filling Ability)
    A --> D(Segregation Resistance)
    B --> E[Flow Through Reinforcement]
    C --> F[Fill Formwork Fully]
    D --> G[Maintain Homogeneity]
    E & F & G --> H[SCC Performance]

Note: SCC improves productivity, reduces vibration/noise, and enhances surface finish, making it suitable for rigid pavements, especially in village roads.

For detailed mix design and tests, refer to Annexures III

IRC SP 62: Materials and Mix Design - Key Specifications & Tables

1. Trial Mix Proportions for M30 Grade Concrete (Table III-3)

2. Fly Ash Properties (Table 6.1)

3. Gradation Curve

• Follow upper and lower limits for aggregate gradations as per Fig. III-1 for SCC.
• Combined gradation ensures workability and strength.

Notes:

• Use trial mixes to optimize concrete performance.
• Maintain w/c ratio close to 0.36-0.38 for durability.
• Fly ash improves workability and reduces heat of hydration.

flowchart LR
    Cement --> Concrete
    FlyAsh --> Concrete
    CrushedSand --> Concrete
    CoarseAggregate --> Concrete
    Water --> Concrete
    SpecialAdmixture --> Concrete
    Concrete --> HardenedConcrete

This summarizes key materials and mix design parameters from IRC SP 62.

IRC SP 62: Design Considerations Summary

Key Design Parameters (Clause 4.5)

• Design Wheel Load: Dual wheel load of 50 kN recommended.
• Concrete Properties:
  • Flexural strength (modulus of rupture)
  • Modulus of elasticity (E)
  • Poisson's ratio (ν)
  • Coefficient of thermal expansion (α)
• Subgrade Reaction: Effective modulus of subgrade reaction (k)
• Traffic: Consider traffic volume (CVPD)

Design Procedure Highlights

1. Input parameters: Wheel load, concrete properties, subgrade modulus, thermal expansion, zone.
2. Select: Tentative slab thickness (h), joint spacing (L), flexural strength.
3. Check stresses: For traffic < 50 CVPD, compute edge stress under dual 50 kN wheel load with tyre pressure 0.80 MPa.
4. Safety check:
   [ \sigma_{edge} \leq f_{r,90} ] where (\sigma_{edge}) = computed edge stress,
   (f_{r,90}) = 90-day modulus of rupture of concrete.

Typical Formula for Edge Stress (Simplified)

[ \sigma = \frac{P}{b \cdot h} + \text{bending stress terms} ] where:

• (P) = wheel load
• (b) = slab width
• (h) = slab thickness

Important Tables (Refer Appendix I for examples)

• Wheel load and tyre pressure values
• Modulus of subgrade reaction values (k)
• Flexural strength vs. concrete grade

flowchart TD
    A[Select Design Parameters] --> B[Assume Slab Thickness & Joint Spacing]
    B --> C[Calculate Edge Stress under Wheel Load]
    C --> D{Is Stress < Modulus of Rupture?}
    D -- Yes --> E[Design is Safe]
    D -- No --> F[Increase Thickness or Adjust Parameters]
    F --> B

Note: Refer to Appendix I for detailed illustrative design examples and Excel spreadsheet inputs.

Key Specifications & Formulas for Joints in Concrete Pavements (IRC SP 62):

1. Transverse (Contraction) Joints

• Spacing: 2.5 m to 4.0 m (2.5 m spacing minimizes curling stresses).
• Width: 3 to 5 mm (narrow joints improve riding quality).
• Depth: 1/4 to 1/3 of slab thickness.
• Formation:
  • Sawing within 24 hours after concrete casting (initial hardening).
  • Alternatively, use mild steel T-section or metal/HDPE strips (3-5 mm thick) embedded before or during casting.
• Sealant: Bituminous sealants as per IS 1834.

2. Expansion Joints

• Provided at abutments of bridges/culverts.
• Width: 20 mm.
• Use dowel bars (25 mm dia @ 250 mm c/c) with plastic tube caps filled with sponge for load transfer.

3. Construction Joints

• Placed where concreting is suspended >90 minutes or at end of day’s work.
• Use steel bulk-heads to retain concrete; ensure surface conformity.

4. Dowel Bar Details

• Diameter: 25 mm
• Spacing: Typically 250 mm c/c (refer Fig. 5(f))
• Position: Centered at mid-depth of slab.

Joint Sawing Depth Formula:

[ \text{Sawing Depth} = (0.25 \text{ to } 0.33) \times \text{Slab Thickness} ]

Acceptance Criteria for Cracks (Clause 7.17):

Summary Table:

| Joint Type | Width (mm) | Depth (of slab) | Spacing (m)

Concrete Mix Design & Properties (IRC SP 62)

Key Specifications:

• Water: 155 - 175 kg/m³ (IS:456 compliant)
• Powder: 375 - 600 kg/m³
• Fine Aggregates: 40-60% of total aggregate weight
• Coarse Aggregates: 750 - 1000 kg/m³
• Water/Paste Volume (w/p): 0.76 to 1.0
• Cement: 240 - 290 kg/m³
• Fly Ash: 160 - 210 kg/m³
• Paste Volume: 34 - 38%
• Water/Binder (cement + fly ash): Max 0.4

Aggregate Gradation (Typical for M30-M40):

Trial Mix Example (kg/m³):

IRC SP 62 - Construction Practices: Key Specifications & Formulas

1. Formwork (Clause 3.0)

• Material: Mild steel channel sections equal to slab thickness, minimum length 3.0 m.
• Wooden forms: Capped with 30-50 mm angle iron inside edge, flush with form face.
• Installation: Held firmly by stakes; forms cleaned and oiled before reuse.
• Removal: After minimum 12 hours of concrete placement.
• Bulkheads: Used at construction joints.
• Note: Formwork can be omitted if a mechanical paver is used.

2. Acceptance Criteria for Cracked Concrete Slabs (Clause 7.17)

3. Design Parameters (Appendix I example)

• Design wheel load: 50 kN
• Tyre pressure: 0.80 MPa
• Subbase: 75 mm WBM over 100-200 mm GSB/cementitious granular layers
• Soil k-value: For CBR=4%, k = 35 MPa/m

4. Construction Notes

• Prevent cracks by controlling moisture loss, timely joint sawing, and ensuring a smooth base.
• Use adequate curing to minimize plastic and drying shrinkage cracks.

flowchart TD
    A[Formwork Setup] --> B[Concrete Placement]
    B --> C[Initial Curing]
    C --> D[Joint Sawing]
    D --> E[Final Curing]
    E --> F[Inspection for Cracks]
    F -->|Acceptable| G[Commissioning]
    F -->|Unacceptable| H[Repair/Reject]

Summary: Proper formwork, curing, and jointing practices per IRC SP 62 ensure durable concrete pavements with acceptable crack control.

Quality Control & Testing per IRC SP 62

1. Sampling & Strength Testing (Clause 7.15)

• For every 100 m³ or a day's work:
  • Sample 6 beams and 6 cubes.
  • Test sets of 3 cubes and beams each at 7 days and 28 days.
• Maintain a quality control chart for individual specimen strength values.
• Refer to IRC:SP:11 for detailed quality control procedures.

2. Self-Compacting Concrete (SCC) Fresh State Tests (Clause 4.1)

• Tests are described in EN 12350-2.
• Annexures III-1 and III-2 detail slump flow and V-funnel tests.

3. Key Notes on SCC

• SCC flows under gravity without vibration.
• Use of superplasticizers and viscosity modifying agents (VMAs) is essential.
• SCC improves productivity, surface finish, and reduces noise and labor.

flowchart LR
    A[Fresh Concrete] --> B{SCC or TPC?}
    B -->|SCC| C[Self-Compaction Tests]
    C --> D[Slump Flow Test]
    C --> E[V-funnel Test]
    C --> F[L-box Test]
    C --> G[Segregation Test]
    B -->|TPC| H[Minimum Slump + Vibration]

Summary:

• Sample 6 beams & cubes per 100 m³ for strength tests at 7 & 28 days.
• SCC quality assessed by slump flow (~400 mm) and V-funnel (~8 s) tests.
• Maintain quality charts and refer to IRC:SP:11 and EN 12350-2 for procedures.

Acceptance Criteria per IRC SP 62

1. Self-Compacting Concrete (SCC) Fresh State Tests (Clause 4.1)

• Tests follow EN 12350-2 standards.
• SCC must flow and consolidate under its own weight without segregation.

2. Acceptance Criteria for Cracked Concrete Slabs (Clause 7.17)

3. Subgrade Support Parameter (Clause 3.1, Table 3.1)

Summary Formula for Crack Acceptance

• Max single crack length ≤ 750 mm (depth < ½ slab thickness)
• Max cumulative crack length ≤ 1250 mm (depth < ½ slab thickness)
• No cracks > ½ slab depth allowed

flowchart TD
    A[Fresh SCC Testing] --> B[Slump Flow ~400 mm]
    A --> C[V-funnel Time ~8 s]
    A --> D[L-box Passing Ability]
    A --> E[Segregation Resistance]

    F[Cr

IRC SP 62: Illustrative Design Example - Key Points

Design Procedure (Clause 4.5 & 4.3)

1. Input Parameters:

   • Design wheel load: Dual 50 kN
   • Concrete flexural strength (modulus of rupture)
   • Effective modulus of subgrade reaction (k-value)
   • Modulus of elasticity of concrete (E)
   • Poisson's ratio (ν)
   • Coefficient of thermal expansion (α)
   • Temperature zone

2. Initial Assumptions:

   • Tentative slab thickness (≥ 150 mm)
   • Joint spacing
   • Flexural strength of concrete

3. Traffic Cases & Stress Checks:

4. Safety Criterion:
   • Edge stress ≤ 90-day modulus of rupture → Safe design

Typical Formula for Edge Stress (Simplified Westergaard's Equation)

[ \sigma = \frac{P}{\sqrt{2 \pi} \cdot h^2} \times f(k, a, E, \nu) ]

Where:

• (P) = wheel load
• (h) = slab thickness
• (k) = modulus of subgrade reaction
• (a) = radius of loaded area
• (E) = modulus of elasticity
• (\nu) = Poisson's ratio

Note: Exact formula and factors are embedded in the provided Excel sheet.

Summary Table for Minimum Slab Thickness

flowchart TD
    A[Start: Input Parameters] --> B{Traffic Volume}
    B

Temperature Distribution & Stress Analysis (IRC SP 62)

Key Points:

• Temperature gradient in concrete slabs is non-linear, with the surface-to-mid depth difference nearly twice the mid-to-bottom difference.
• Temperature stresses are reduced at the slab bottom due to this non-linearity (see Appendix II).
• Bradbury's Equation (Clause 4.8) is used for stress calculation assuming a linear temperature gradient:

[ \sigma_{te} = E \alpha t C ]

Where:

• ( \sigma_{te} ) = temperature stress at edge (MPa)
• ( E ) = Modulus of elasticity of concrete (MPa)
• ( \alpha ) = Coefficient of thermal expansion
• ( t ) = Temperature difference between top and bottom (°C)
• ( C ) = Coefficient from slab geometry & stiffness ratio (from Bradbury's curve)

Recommended Temperature Differentials (Table 4.1):

Notes:

• Use local temperature differential data if available.
• For non-linear gradients, separate linear and curling stresses (Appendix II).
• Coefficient (C) is obtained from Bradbury's curves based on slab length/width and radius of relative stiffness.

flowchart TD