Do It Yourself Cell Filled Concrete Pavement
2015 Edition

Introduction to Cell Filled Concrete Pavements (MORD 26)

• Concept: Modular plastic cells (0.22 mm thick, 150 mm side length, 100 mm depth) create compartments filled with concrete to enhance pavement performance.
• Materials:
  • Coarse Aggregate: Crushed stone or gravel with impact value below 30%, flakiness index under 40%, maximum size 26.5 mm.
  • Fine Aggregate: Clean natural sand or crushed stone.
• Aggregate Gradation (Table 1):

• Subgrade Preparation:

  • Top 300 mm compacted to at least 100% of maximum dry density per IS:2729 Part 7.
  • Expansive soils compacted to 95% maximum dry density with moisture content 2% above optimum; lime stabilization advised.
  • CBR tests after soaking to confirm soil stability.

• Construction Aids:

  • Iron spikes approximately 200 mm long and nylon threads used to maintain cell tension during concrete placement.

Refer to IRC:44-2008 for mix design details.

flowchart TD
    A[Plastic Cells] --> B[Concrete Filling]
    B --> C[Enhanced Pavement Strength]
    A --> D[Secured by Iron Spikes & Nylon Threads]
    E[Prepared Subgrade] --> F[Compaction to 100% MDD]
    F --> B

This introduction sets the stage for understanding and executing cell filled concrete pavements per MORD 26.

Fundamental Concept of Cell Filled Concrete Pavement (MORD 26)

Core Principle: Plastic modular cells are placed over a well-prepared subbase to create a cellular matrix. Concrete fills each cell, forming small interlocked blocks that distribute loads effectively, minimize cracking, and improve durability—particularly suited for low-traffic rural roads.

Specifications and Highlights:

• Plastic Cells: Installed on compacted subbase and tensioned with iron spikes.
• Concrete Filling: Cells filled to approximately 120 mm depth (20 mm above cell height).
• Compaction: Employ roller compacted concrete (RCC) or vibratory rollers.
• Edge Restraints: Stone, concrete blocks, or bricks placed on edges, projecting 50-100 mm above subbase.
• Hard Shoulders: 0.85 m wide on both sides with proper camber.
• Drainage: Necessary in regions with annual rainfall exceeding 1000 mm.

Aggregate Gradation for Concrete (Table 1):

Concrete Requirements:

• Coarse Aggregates: Crushed stone or gravel with impact value below 30%, maximum size up to 26.5 mm.
• Fine Aggregates: Clean natural sand or crushed stone.
• Mix Design: Follow IRC:44-2008 or Clause 1502.8 for RCC.
• Water: Carefully measured; add more in dry or hot conditions.

Construction Process Overview:

flowchart TD
    A[Subgrade & Subbase Preparation] --> B[Placement of Plastic Cells]
    B --> C[Secure Cells with Iron Spikes]
    C --> D[Concrete Filling (~120 mm Depth)]
    D --> E[Concrete Compaction (Roller/Vibration)]
    E --> F[Remove Spikes & Cure Surface]
    F --> G[Install Edge Protection & Hard Shoulders]
    G --> H[Open Pavement to Traffic After Curing]

This section explains the primary concept behind the cell filled concrete pavement system.

Details of Plastic Cells for Concrete Pavements (MORD 26)

Essential Specifications:

• Cell Dimensions: Side lengths from 150 mm up to 200 mm; depth about 100 mm.
• Plastic Sheet Thickness: Typically 0.22 mm Low-Density Polyethylene (LDPE).
• Weight of Sheets: Approximately 1250 kg required for a 3.75 m wide, 1 km long pavement.
• Cell Formation: Strips welded at 300 mm intervals in an alternating pattern for stability.
• Iron Spikes: Around 200 mm long spikes used to maintain tension in cell walls during concrete placement.
• Nylon Threads: Inserted to support cell walls and prevent collapse; removed post-placement.
• Formwork Roll Length: Each roll covers a length of 10 to 20 meters across 3.75 m width.

Construction Considerations:

• Concrete slump targeted between 30 to 50 mm to facilitate placement and vibration.
• Cell walls deform slightly during vibration, promoting interlocking.
• Surface camber between 2.5% and 3.0% ensures proper drainage.
• Subgrade moisture conditioning prevents premature water loss from concrete.

Diagram: Plan View of Plastic Cell

graph TD
    A[Plastic Cell Plan] --> B[Side Length 150-200 mm]
    A --> C[Depth 100 mm]
    A --> D[Welded Strips at 300 mm Intervals]
    A --> E[Iron Spikes 200 mm Long]
    A --> F[Nylon Threads for Support]

This system guarantees modular, stable formwork for effective concrete pavement construction with controlled thickness and longevity.

Subgrade Preparation - Key Standards (MORD 26)

• Thickness: Top 300 mm of embankment soil.
• Material Quality: Use soils with CBR greater than 5; if embankment soil is poor, borrow quality soil.
• Compaction:
  • Perform compaction in two layers.
  • Achieve at least 100% maximum dry density according to IS:2729 (Part 7).
  • For expansive black cotton soils, compact to 95% MDD with moisture content 2% above optimum.
• Stabilization: Lime stabilization is advised to reduce swelling and increase strength in expansive soils.
• CBR Testing: Conduct soaked CBR tests at field density and moisture conditions after 4 days soaking; Dynamic Cone Penetration Tests may be used for quick estimates.
• Subbase Materials: Include laterite boulder consolidation, water bound macadam, stabilized soils, etc.
• Subbase Strength: For traffic exceeding 50 commercial vehicles daily, provide a cementitious subbase at least 150 mm thick with minimum 7-day compressive strength of 1.5 MPa.
• Edge Restraints: Stone or concrete blocks or bricks should project 50 to 100 mm above subgrade or subbase to confine the pavement.

Aggregate Gradation (Table 1)

• Coarse aggregates should have impact value under 30% and flakiness index less than 40%.
• Fine aggregates must be clean natural sand or crushed stone as specified.

Dry Density Calculation (IS:2729)

[ \text{Dry Density} = \frac{\text{Wet Density}}{1 + w} ]

where (w) is moisture content expressed as a decimal.

flowchart TD
    A[Subgrade Soil] --> B[First Layer Compacted]
    B --> C[Second Layer Compacted]
    C --> D[CBR Testing]

This ensures a stable foundation for the pavement structure.

Subbase Requirements and Preparation (MORD 26)

• Materials: Laterite boulder consolidation, water bound macadam, wet mix macadam, jhama brick consolidation, crusher-run macadam, lime-fly ash-aggregate blends, lime or cement stabilized soils, proprietary stabilizers, and locally sourced aggregates like murrum and kankar.
• CBR Criteria: Stabilized soils should have a soaked CBR of at least 20 if quality aggregates are unavailable or costly.
• Thickness: For roads carrying more than 50 commercial vehicles daily, a minimum 150 mm cementitious subbase is mandatory.
• Strength: Cementitious subbase must achieve a minimum 7-day compressive strength of 1.5 MPa.
• Edge Restraint: Stone or concrete blocks or bricks should be placed on the edges projecting 50-100 mm above the adjacent subgrade or subbase.

Subgrade Preparation Recap

• Top 300 mm compacted in two layers at greater standards than embankment.
• Use borrow soil with CBR above 5 if embankment soil is deficient.
• Compaction to at least 100% MDD (95% for black cotton soil) with moisture control.
• Lime stabilization recommended for expansive soils.
• CBR testing after soaking; Dynamic Cone Penetration for rapid assessment.

Summary Table

flowchart TD
    A[Prepare Subgrade] --> B[Compaction to ≥ 100% MDD]
    B --> C[Use Borrow Soil if Required]
    C --> D[CBR Testing ≥ 5]
    D --> E[Construct Subbase Layer]

This approach guarantees a robust base for pavement longevity.

Concrete Mix and Material Specifications (Clause 26.5 and related)

Coarse Aggregates:

• Strong crushed stone or gravel.
• Aggregate Impact Value (per IS:2386 Part 4) below 30%.
• Flakiness Index not exceeding 40%.
• Maximum aggregate size of 26.5 mm.
• For roads with very low traffic (< 50 vehicles/day), riverbed gravels may be acceptable.

Fine Aggregates:

• Clean natural sand or crushed stone.
• Must comply with gradation requirements.

Aggregate Gradation (Table 1)

Mix Proportioning and Materials Handling

• Proportions should be based on weight for cement, sand, and aggregates.
• Use calibrated steel measuring boxes for cement and calibrated containers for aggregates.
• Water volume should be controlled with permanent marks on containers.

Concrete Strength and Design

• Follow IRC:44-2008 for mix design of cement concrete pavements.
• Minimum 28-day compressive strength of about 30 MPa.
• Conventional concrete slump range between 30 to 50 mm.
• Use superplasticizers to reduce water demand without compromising workability.
• Roller Compacted Concrete (RCC) is also acceptable and compacted using rollers as per Clause 1502.

Construction Notes

• Fill plastic cells with concrete to a depth of roughly 120 mm (20 mm above cell height).
• Compact concrete with vibratory and static rollers.
• Cover surface with wet jute mats or paddy straw for curing.
• In hilly regions, transverse grooves (250 mm wide, 200 mm deep) spaced 15-20 m apart help prevent slippage.

flowchart TD
    A[Select Aggregates] --> B[Coarse Aggregate: Impact < 30, Max 26.5 mm]
    A --> C[Fine Aggregate: Clean Sand or Crushed Stone]
    B & C --> D[Aggregate Gradation per Table 1]
    D --> E[Concrete Mix Design]

These specifications ensure strong and durable concrete suitable for rural pavement applications.

Detailed Mix Design Requirements (MORD 26)

Aggregate Criteria (Clause 26.5)

• Coarse Aggregate:

  • Strong crushed stone or gravel with Aggregate Impact Value less than 30% (IS:2386 Part 4).
  • Flakiness Index below or equal to 40%.
  • Maximum size limited to 26.5 mm.
  • For very low traffic roads (< 50 vehicles/day), riverbed gravel permitted.

• Fine Aggregate:

  • Clean natural sand or crushed stone complying with specifications.

Aggregate Gradation (Table 1)

Mix Proportioning

• Proportions computed by weight for cement, sand, and aggregates.
• Use calibrated steel boxes for cement and calibrated containers for aggregates.
• Water amount controlled via permanent markings on measuring containers.

Concrete Types and Strength Requirements

• Conventional concrete with 28-day strength around 30 MPa; slump 30-50 mm.
• Use superplasticizers to lower water demand.
• Roller Compacted Concrete (RCC) with minimum 28-day strength of 30 MPa is acceptable.
• Fly ash from electrostatic precipitators can partially substitute OPC-53 cement; do not use bottom or pond ash or fly ash with pozzolana or slag cement.

Additional Guidelines

• Conduct trial mixes to finalize proportions following IRC:44-2008.
• Adjust water content for aggregate moisture and hot climate evaporation.
• Ensure proper curing and compaction for quality results.

Mix Design Workflow

flowchart TD
    A[Select Suitable Aggregates] --> B[Check Impact Value & Flakiness]
    B --> C[Verify Gradation per Table 1]
    C --> D[Proportion Cement, Sand, Aggregates by Weight]
    D --> E[Adjust Water Content]
    E --> F[Conduct Trial Mixes and Strength Tests]
    F --> G[Finalize Mix Design]

This method guarantees durable and workable concrete for cell filled pavements.

Construction Specifications and Formulas for Cell Filled Concrete Pavement (MORD 26)

1. Subgrade and Subbase Preparation

• Prepare top 300 mm of subgrade in two compacted layers.
• Use materials with CBR at least 5.
• Compact to a minimum of 100% maximum dry density (IS:2729 Part 7).
• For expansive black cotton soil, compact to 95% MDD with moisture 2% above optimum.
• Lime stabilization recommended for black cotton soil.

2. Plastic Cell Formworks

• Use plastic cells 100 mm deep, 150 mm side length, made from 0.22 mm thick sheets.
• Employ iron spikes (200 mm length) and nylon threads to maintain cell tension and prevent collapse.
• Fill cells with concrete to 120 mm depth (20 mm above cell height).
• Remove spikes after concrete placement.

3. Concrete Mix and Aggregates

• Coarse aggregates: maximum 26.5 mm size, impact value below 30, flakiness index below 40%.
• Fine aggregates: clean sand or crushed stone.
• Aggregate gradation as per Table 1.
• Design mix following IRC:44-2008 or Clause 1502.8.

4. Compaction

• For RCC, compact using 1-2 static passes, 2 vibratory passes, followed by 1 static pass.
• Adjust passes according to aggregate characteristics.
• For conventional concrete, use pan vibrators (slump 30-40 mm).

5. Edge Protection and Hard Shoulders

• Install stone, concrete blocks, or bricks on edges projecting 50-100 mm above subgrade.
• Hard shoulders 0.85 m wide with appropriate camber.

6. Special Considerations

• In hilly terrain, provide transverse grooves (250 mm wide, 200 mm deep) every 15-20 m to prevent slippage.

Joint Design Parameters (Clause 9, Page 9, MORD 26):

• Spacing: Joints spaced regularly (typically 3 to 4.5 meters) to manage cracking.

• Types:

  • Contraction Joints: Control shrinkage cracks.
  • Expansion Joints: Allow for thermal expansion.
  • Construction Joints: At daily work stoppage points.

• Details:

  • Reinforcement strips welded at 300 mm intervals across joints.
  • Joints sealed with appropriate materials to prevent water and debris ingress.

Aggregate Gradation Table (Ensuring Quality at Joints)

Notes:

• Use strong crushed stone with impact values below 30% to protect joint integrity.
• Maintain flakiness index below 40%.
• Joint design must accommodate thermal movements and ensure load transfer.
• Follow IRC:44-2008 for mix design to optimize joint performance.

flowchart LR
    A[Concrete Pavement] --> B[Joints]
    B --> C[Contraction Joints]
    B --> D[Expansion Joints]
    B --> E[Construction Joints]
    C --> F[Control Shrinkage]
    D --> G[Allow Thermal Movement]
    E --> H[Work Break Points]
    B --> I[Reinforcement: Welded Strips @ 300 mm]
    B --> J[Joint Sealants]

This ensures joints effectively control cracking and maintain pavement durability.

Quality Assurance in Concrete Pavement (MORD 26)

Essential Tests Following Construction (Clause 17.0)

• Destructive Tests:

  • Extract pavement cores.
  • Test cores for compressive strength and structural integrity.

• Non-Destructive Tests:

  • Visual inspection for defects such as blow-ups, corner breaks, cracks, faulting, and pumping.
  • Benkel Beam Deflection Test:
    • Measures pavement deflection under load.
    • Test locations:
      • 0.9 m from edge on main roads (5.5 m width).
      • 0.6 m from edge on other roads (3.75 m width).
    • Tests conducted at intervals of 100 m along the pavement.

Additional Notes:

• Regular testing is crucial for pavement durability.
• Visual checks help detect early surface distresses.
• Deflection testing evaluates load-bearing and structural condition.

flowchart LR
    A[Concrete Pavement] --> B[Quality Control]
    B --> C[Destructive Testing]
    B --> D[Non-Destructive Testing]
    D --> E[Visual Inspection]
    D --> F[Benkel Beam Deflection]
    F --> G[Measure at 0.9 m (Main Roads)]
    F --> H[Measure at 0.6 m (Other Roads)]
    F --> I[Every 100 m]

Refer to MORD 26 Tables and clauses for detailed testing and curing procedures.

Curing Methods and Requirements (MORD 26)

Clause 3.5 Highlights:

• Rural roads with 3 to 3.5% camber benefit from wet curing using jute/coir mats or wet paddy straw (see Fig. 10).
• These materials hold moisture better than ponding, allowing light traffic during curing.
• Ponding leads to water accumulation on lower surface side and drying on the higher side.

Recommended Curing Techniques

Practical Recommendations:

• Cover freshly finished concrete immediately to prevent moisture loss.
• Maintain curing for at least 7 days under normal conditions.
• In hot climates, ensure continuous wetting or cover with wet mats/straw.
• Permit only light traffic until adequate curing has been achieved.

Visual Flow of Curing Methods

flowchart LR
    A[Fresh Concrete] --> B[Cover with Wet Jute/Coir Mats or Paddy Straw]
    B --> C[Maintain Moisture Continuously]
    A --> D[Water Ponding]
    D --> E{Is Surface Cambered?}
    E -- Yes --> F[Water Runs Off; Uneven Curing]
    E -- No --> G[Water Retained; Effective Curing]

Summary:

• Wet mats or straw are preferred for moisture retention on cambered rural pavements.
• Ponding is less reliable due to runoff effects.
• Proper curing is essential for concrete strength development and durability.

Refer to relevant clauses in MORD 26 and IRC:44-2008 for curing guidelines.

Traffic Opening Recommendations (MORD 26)

• Curing & Early Traffic:

  • Use wet jute/coir mats or wet paddy straw for curing on roads with 3-3.5% camber.
  • These methods permit light traffic during curing.
  • Ponding is less effective on cambered surfaces due to uneven water distribution.

• Timing:

  • Light traffic permitted after initial curing phase (3-7 days depending on strength gain).
  • Full traffic loading allowed once concrete achieves design strength (typically 28 days).

• Quality Checks Before Opening:

  • Conduct destructive testing (core extraction and strength assessment).
  • Perform non-destructive evaluations (visual inspection for cracks, blow-ups, corner breaks).
  • Utilize Benkel Beam Deflection Test:
    • Deflection measured 0.9 m from edge on 5.5 m wide roads.
    • Deflection measured 0.6 m from edge on 3.75 m wide roads.
    • Measurements every 100 m along pavement.

Summary Table: Traffic Opening Criteria

flowchart TD
    A[Concrete Placement] --> B[Curing with Wet Mats/Straw]
    B --> C{Initial Curing Period (3-7 Days)}
    C -->|Complete| D[Allow Light Traffic]
    D --> E{Concrete Strength Adequate?}
    E -->|No| D
    E -->|Yes| F[Allow Full Traffic]
    F --> G[Conduct Quality Tests]

This protocol ensures safe traffic introduction, minimizing damage risk.

Top Surface Appearance Considerations (MORD 26)

• Visual Aspects (Clause 13):

  • Outlines of plastic formwork are visible on the pavement surface (see Fig. 11).
  • If concrete thickness exceeds 100 mm, the plastic cell impressions may not be apparent.
  • Cracks tend to appear along joints in plastic sheets after months of traffic, reflecting the formwork pattern.

• Curing Effects (Clause 3.5):

  • A camber of 3-3.5% enhances water curing efficiency.
  • Wet jute or coir mats and wet paddy straw improve curing and allow light traffic.
  • Ponding causes uneven curing due to water pooling on lower side.

• Aggregate Gradation (Clause 26.5):

• Aggregate Quality:
  • Coarse aggregates with impact value below 30% (IS:2386 Part 4).
  • Flakiness index below 40%.
  • Maximum size limited to 26.5 mm.

Diagram: Surface Appearance and Curing Interaction

flowchart LR
    A[Plastic Formwork] --> B[Visible Surface Outlines]
    B --> C[Cracks Form Along Joints]
    D[Camber 3-3.5%] --> E[Improved Water Curing]
    E --> F[Use of Wet Jute/Coir Mats or Paddy Straw]
    F --> G[Light Traffic Permitted]
    H[Ponding Method] --> I[Uneven Water Distribution]
    I --> J[Drying on Elevated Surface]

Note: Proper curing and aggregate grading are essential for a durable and visually satisfactory pavement surface.

The Grouting Technique for flexible concrete pavements (Clause 14, MORD 26) involves filling pre-set plastic cells or voids with grout to form a composite pavement layer.

Key Steps and Specifications:

• Lay plastic cells (usually 100 mm deep) on prepared subgrade or subbase.
• Fill cells with cement grout or lean concrete to create a rigid base.
• Grout mix typically uses a water-cement ratio between 0.4 and 0.5 for optimal flow and strength.
• Grout thickness corresponds to cell depth (commonly 100 mm).
• After filling, finish the surface smoothly and apply curing methods such as wet mats or ponding.

Important Considerations:

• Ensure grout fluidity to avoid voids.
• Proper curing is critical to minimize shrinkage cracks.
• Pavement thickness (grout plus overlay) is designed based on traffic loading requirements (see Clause 15).

Typical Grout Mix Ratios:

flowchart TD
    A[Prepare Subgrade] --> B[Place Plastic Cells]
    B --> C[Pour Cement Grout into Cells]
    C --> D[Finish Surface]
    D --> E[Curing (Wet Mats or Ponding)]
    E --> F[Open to Traffic]

This method enhances load distribution and reduces pavement thickness while maintaining flexibility.

Thickness Guidelines for Cell Filled Concrete Pavements

Based on MORD 26 and Relevant IS Codes:

• Concrete Layer Thickness:

  • Ranges from 50 mm to 100 mm depending on traffic volumes.
  • For very low traffic roads (<50 motorized vehicles daily), a thickness of 100 mm is preferred to ensure adequate support when subgrade CBR is at least 5.

• Subbase Thickness:

  • Minimum 100 mm granular subbase (GSB) recommended beneath 75 mm and 100 mm concrete layers.
  • Thickness depends on cumulative standard axle load repetitions (see Figures 12 & 13 in MORD 26).
  • If GSB is unavailable, lime or cement stabilized soil or lime-fly ash stabilized soil may be used.

• Aggregate Requirements (Clause 26.5):

  • Coarse aggregates with maximum size 26.5 mm, impact value below 30%, flakiness index below 40%.
  • Fine aggregates shall be clean natural sand or crushed stone.
  • Aggregate gradation as per Table 1.

• Concrete Strength:
  • Approximately 25 MPa or higher 28-day cube strength for grout method.

Thickness Summary Table

Pavement Layer Diagram

graph TD
    A[Cell-Filled Concrete (50-100 mm)] --> B[Granular Subbase (≥ 100 mm)]
    B --> C[Subgrade with CBR ≥ 5]

References: MORD 26, IRC standards, and IS codes for detailed design.

Benefits of Cell Filled Concrete Pavements (MORD 26, Clause 16.0):

• Elimination of Expansion/Contraction Joints: No joints needed, reducing maintenance.
• Cost Efficiency: Lower construction costs compared to conventional cement concrete pavements.
• Aggregate Conservation: Approximately 50% less aggregate usage than traditional CC pavements.
• Reduced Pavement Thickness: High stiffness allows thinner pavement layers, suitable for low-traffic roads.
• Ease of Repair: Individual damaged blocks can be replaced easily and economically.
• Environmental Benefit: Utilizes recycled plastic in formworks.

Summary Table of Advantages

Notes:

• Careful cell preparation and concrete placement are required to avoid disturbances.
• Construction is labor-intensive and slower compared to conventional methods.

flowchart LR
    A[Plastic Cell Usage] --> B[Reduced Aggregate Consumption]
    B --> C[Lower Construction Expenses]
    A --> D[No Expansion Joints]
    D --> E[Maintenance-Free Pavement]
    C --> F[Economical Pavement Thickness]
    F --> G[Ideal for Low Traffic]
    E --> H[Extended Pavement Life]
    A --> I[Simple Block Repairs]

This highlights the key benefits as per MORD 26 Clause 16.0.

Quality Testing After Construction (MORD 26, Clause 17.0):

1. Destructive Testing:

   • Extract cores from the pavement.
   • Test cores for compressive strength, density, and overall integrity.

2. Non-Destructive Testing:

   • Visual inspection for surface defects including blow-ups, corner breaks, cracking, faulting, and pumping.

3. Benkel Beam Deflection Testing:

   • Measures pavement deflection to assess structural capacity.
   • Deflection measurement points:
     • 0.9 m from edge for main roads (5.5 m width).
     • 0.6 m from edge for other roads (3.75 m width).
   • Tests performed every 100 meters along the pavement.

Deflection Measurement Summary

Notes: Core extraction and Benkel Beam deflection tests confirm pavement strength and durability. Visual inspections help identify early surface distress.

flowchart LR
    A[Post-Construction Testing] --> B[Destructive Tests]
    A --> C[Non-Destructive Visual Inspection]
    A --> D[Benkel Beam Deflection Test]
    B --> E[Core Extraction and Strength Testing]
    C --> F[Surface Defect Identification]
    D --> G[Deflection Measurement at 0.9m or 0.6m]
    G --> H[Tests at 100m Intervals]

This comprehensive testing ensures pavement reliability and longevity.