Do It Yourself Cell Filled Concrete Pavement

Introduction to Cell Filled Concrete Pavement (MORD 26)

• Concept: Plastic cells (0.22 mm thick, 150 mm side, 100 mm depth) form modular compartments filled with concrete, improving pavement performance.
• Materials:
  • Coarse Aggregate: Crushed stone/gravel, impact value < 30%, flakiness index < 40%, max size 26.5 mm.
  • Fine Aggregate: Clean natural sand/crushed stone.
• Aggregate Gradation (Table 1):

• Subgrade Preparation:

  • Top 300 mm compacted to ≥ 100% max dry density (IS:2729 Part 7).
  • Expansive soils compacted at 95% max dry density with +2% moisture; lime stabilization recommended.
  • CBR tests after soaking for stability confirmation.

• Construction Aids:

  • Iron spikes (~200 mm) and nylon threads used to keep cells taut during concrete placement.

For mix design, refer IRC:44-2008 guidelines.

flowchart TD
    A[Plastic Cells] --> B[Filled with Concrete]
    B --> C[Improved Pavement Strength]
    A --> D[Held taut by Iron Spikes & Nylon Threads]
    E[Prepared Subgrade] --> F[Compact to 100% MDD]
    F --> B

This summary provides the foundation for understanding and implementing cell filled concrete pavements per MORD 26.

The Concept of Cell Filled Concrete Pavement (MORD 26)

Key Idea:
Plastic cells (modular formwork) are placed on a prepared subbase to create a cellular structure. These cells are filled with concrete, confining it in small blocks that improve load distribution, reduce cracking, and enhance durability especially for low volume rural roads.

Specifications & Key Points:

• Plastic Cells: Laid on compacted subbase, tensioned with iron spikes.
• Concrete Filling: Filled to ~120 mm depth (20 mm above cell height).
• Compaction: Use roller compacted concrete (RCC) or vibratory rollers.
• Edge Protection: Stone/concrete blocks or bricks on edge, projecting 50-100 mm above subbase.
• Hard Shoulder: 0.85 m width each side with proper camber for stability.
• Drainage: Required in areas with >1000 mm annual rainfall.

Aggregate Gradation for Concrete (Table 1):

Concrete Requirements:

• Coarse Aggregate: Crushed stone/gravel, impact value < 30, max size ≤ 26.5 mm.
• Fine Aggregate: Clean natural sand or crushed stone.
• Mix Design: Follow IRC:44-2008 or Clause 1502.8 for RCC mix design.
• Water: Measure carefully; add extra if dry during hot weather.

Construction Steps Summary:

flowchart TD
    A[Prepare Subgrade & Subbase] --> B[Place Plastic Cells]
    B --> C[Tension Cells with Iron Spikes]
    C --> D[Fill Cells with Concrete (~120 mm)]
    D --> E[Compact Concrete (Roller/Vibratory)]
    E --> F[Remove Spikes & Cure Surface]
    F --> G[Edge Protection & Hard Shoulder]
    G --> H[Open to Traffic after Curing]

This concept

Plastic Cells in Concrete Pavement (MORD 26)

Key Specifications:

• Cell dimensions: Side length varies from 150 mm to 200 mm, depth about 100 mm.
• Plastic sheet thickness: Typically 0.22 mm LDPE sheets.
• Weight of plastic sheets: ~1250 kg for a 3.75 m wide, 1 km long road.
• Cell stitching: Strips welded at 300 mm intervals, with alternating stitching for stability.
• Iron spikes: About 200 mm long spikes keep cell walls taut during concrete placement.
• Nylon threads: Used to prevent collapse of cell walls; removed after concrete placement.
• Formwork length: One roll covers 10 to 20 m length for 3.75 m width pavement.

Construction Notes:

• Concrete slump: 30 to 50 mm for easy placement and vibration.
• Cell walls deform during vibration, creating interlocking.
• Surface camber: 2.5% to 3.0% for drainage.
• Subgrade should be moistened to prevent water loss from concrete.

Diagram (Plan View of Plastic Cell):

graph TD
    A[Plastic Cell Plan View]
    A --> 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 ensures modular, stable formwork for efficient concrete pavement construction with controlled thickness and durability.

Preparation of Subgrade — Key Points & Specifications (MORD 26)

• Subgrade Thickness: Top 300 mm of embankment.
• Material Quality: Use good quality soil with CBR > 5 if embankment soil is poor.
• Compaction:
  • Compact in two layers.
  • Achieve ≥ 100% Maximum Dry Density as per IS:2729 (Part 7).
  • For expansive black cotton soil (BCS), compact to ≥ 95% MDD at 2% above optimum moisture.
• Stabilization: Lime stabilization recommended for BCS to reduce swelling and improve strength.
• CBR Testing: Conduct CBR at in-situ dry density and moisture after 4 days soaking. Dynamic cone penetration test can estimate CBR quickly.
• Subbase: Various materials allowed (laterite, WBM, stabilized soils). For >50 commercial vehicles/day, use 150 mm cementitious subbase with ≥ 1.5 MPa 7-day strength.
• Edge Protection: Stone/concrete blocks or bricks projecting 50-100 mm above subgrade/subbase for confinement.

Aggregate Gradation for Concrete (Table 1)

• Coarse aggregates: Impact value < 30%, flakiness index < 40%, max size ≤ 26.5 mm.
• Fine aggregates: Clean natural sand/crushed stone as per specifications.

Compaction and Density Formula (IS:2729)

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

where (w) = moisture content (decimal).

flowchart TD
    A[Subgrade Soil] --> B[Layer 1: Compacted]
    B --> C[Layer 2: Compacted]
    C --> D[CBR

Subbase Specifications & Key Points (MORD 26)

• Materials: Laterite boulder consolidation, water bound macadam, wet mix macadam, jhama brick consolidation, crusher run macadam, lime-fly ash-aggregate mixtures, lime/cement stabilized soil, proprietary stabilizers, locally available aggregates (murrum, kankar).
• CBR Requirement: Soaked CBR ≥ 20 for stabilized soils if aggregates are costly/unavailable.
• Thickness:
  • Minimum 150 mm cementitious subbase if > 50 commercial vehicles/day.
• Strength: Minimum 7-day compressive strength of 1.5 MPa for cementitious subbase.
• Edge Protection: Stone/concrete blocks or bricks on edge projecting 50 to 100 mm above subgrade/subbase on carriageway sides for confinement.

Preparation of Subgrade (Top 300 mm of embankment)

• Compacted in two layers, to higher standards than embankment.
• Use good quality borrow soil with CBR > 5 if embankment soil is poor.
• Compaction: ≥ 100% Maximum Dry Density (IS 2729 Part 7).
• For black cotton soil: ≥ 95% MDD at 2% above optimum moisture; lime stabilization recommended.
• CBR testing after 4 days soaking; Dynamic Cone Penetration Test for quick CBR estimation.

Summary Table

flowchart TD
    A[Subgrade Preparation] --> B[Compaction to ≥ 100% MDD]
    B --> C[Use borrow soil if poor subgrade]
    C --> D[CBR Testing (≥5)]
    D --> E[Subbase Layer

Key Specifications & Tables for Concrete (Clause 26.5 & related)

Coarse Aggregates:

• Type: Strong crushed stone or crushed gravel
• Aggregate Impact Value (IS:2386 Part 4): < 30
• Flakiness Index: ≤ 40%
• Max size: 26.5 mm
• For very low volume roads (< 50 vehicles/day): riverbed gravels allowed

Fine Aggregates:

• Clean natural sand or crushed stone
• Must meet gradation requirements

Aggregate Gradation for Concrete (Table 1)

Mix Proportioning & Materials

• Proportion by weight (aggregate, sand, cement)
• Use calibrated measuring boxes for volume batching
• Cement: Use steel measuring boxes only
• Water quantity: Mark container for specified volume

Concrete Strength & Mix Design

• Use IRC:44-2008 for cement concrete mix design for pavements
• Minimum 28-day compressive strength: 30 MPa
• Slump for conventional concrete: 30-50 mm
• Use superplasticizers to reduce water demand
• Roller Compacted Concrete (RCC) also suitable, compacted with rollers (Clause 1502)

Additional Notes on Construction

• Use plastic cells filled with concrete to 120 mm depth (~20 mm above cell height)
• Proper compaction with vibratory and static rollers
• Cover surface with wet jute mats/paddy straw for curing
• Transverse grooves (250 mm wide × 200 mm deep) at 15-20 m intervals in hilly terrain to prevent slippage

flowchart TD
    A[Aggregate Selection] --> B[Coarse Aggregate: Impact Value < 30, Max size 26.5mm]
    A --> C[Fine Aggregate: Clean sand/crushed stone]
    B & C --> D[Aggregate Gradation as

Key Mix Design Specifications & Tables (MORD 26)

Aggregate Requirements (Clause 26.5)

• Coarse Aggregate:

  • Strong crushed stone/gravel with Aggregate Impact Value < 30 (IS:2386 Part 4)
  • Flakiness Index ≤ 40%
  • Max size ≤ 26.5 mm
  • For very low volume roads (<50 vehicles/day), riverbed gravel allowed

• Fine Aggregate:

  • Clean natural sand or crushed stone meeting specifications

Aggregate Gradation (Table 1)

Mix Proportioning

• Proportion by weight (cement, sand, aggregates)
• Use calibrated measuring boxes for volume measurement
• Water quantity fixed by permanent mark on container

Concrete Types & Strength

• Conventional concrete: 28-day strength ~ 30 MPa, slump 30-50 mm
• Use superplasticiser to reduce water demand
• Roller Compacted Concrete (RCC) also used with minimum 28-day strength 30 MPa
• Fly ash (electrostatic precipitator type) allowed as partial OPC replacement (not with pozzolana/slag cement)

Additional Notes

• Trial mixes essential to finalize proportions (IRC:44-2008 recommended)
• Adjust water for moisture in aggregates and hot weather conditions
• Proper curing and compaction methods critical for quality

Summary Flow for Mix Design

flowchart TD
    A[Select Aggregates] --> B[Check Impact Value & Flakiness]
    B --> C[Ensure Gradation per Table 1]
    C --> D[Proportion Cement, Sand, Aggregates by Weight]
    D --> E[Adjust Water Content for Moisture & Slump]
    E --> F[Trial Mixes & Strength Testing]
    F --> G[Finalize Mix Design]

This ensures durable, workable concrete suitable for cell-filled pavements in rural roads

Key Specifications & Formulas for Construction of Cell Filled Concrete Pavement (MORD 26)

1. Subgrade & Subbase Preparation

• Subgrade top 300 mm compacted in two layers.
• CBR ≥ 5 for borrow pit material.
• Compaction: ≥ 100% Maximum Dry Density (IS:2729 Part 7).
• Expansive black cotton soil: 95% max dry density, moisture 2% above optimum.
• Lime stabilization recommended for black cotton soil.

2. Plastic Cell Formwork

• Plastic cells: thickness 100 mm, side 150 mm, thickness of sheet 0.22 mm.
• Use iron spikes (200 mm long) and nylon threads to keep cells taut and prevent collapse.
• Concrete fill depth: 120 mm (20 mm above cell height).
• Remove spikes after filling.

3. Concrete Mix & Aggregates

• Coarse aggregates max size: 26.5 mm; Impact value < 30; Flakiness index < 40%.
• Fine aggregates: clean natural sand or crushed stone.
• Aggregate gradation (Table 1):

• Use IRC:44-2008 or clause 1502.8 for mix design.

4. Compaction

• RCC compaction: 1-2 static passes + 2 vibratory passes + 1 static pass.
• Adjust passes based on aggregate texture and moisture.
• Use pan vibrators for conventional concrete (slump 30-40 mm).

5. Edge Protection & Hard Shoulder

• Stone/concrete block or brick on edge, projecting 50-100 mm above subgrade.
• Hard shoulder width: 0.85 m with proper camber.

6. Special Construction Notes

• Transverse grooves (250 mm wide, 200 mm deep) every 15-20 m in hilly terrain to prevent

Key Specifications and Formulas for Joints (Clause 9, Page 9, MORD 26):

• Joint Spacing: Typically, joints are provided at regular intervals (e.g., 3 to 4.5 m for concrete pavements) to control cracking.

• Types of Joints:

  • Contraction Joints: To control shrinkage cracks.
  • Expansion Joints: To accommodate thermal expansion.
  • Construction Joints: At the end of a day's work.

• Joint Details:

  • A pair of strips welded at 300 mm intervals is used for reinforcement across joints.
  • Joints should be filled with suitable sealants to prevent ingress of water and debris.

Aggregate Gradation Table (Related to Concrete Quality at Joints)

Important Notes:

• Use strong crushed stone aggregates with impact value < 30% to avoid damage near joints.
• Maintain flakiness index < 40% for aggregates.
• Joint design should consider thermal expansion, shrinkage, and load transfer.
• Follow IRC:44-2008 for concrete mix design which impacts 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 Cracks]
    D --> G[Allow Thermal Expansion]
    E --> H[Work Stoppage Points]
    B --> I[Reinforcement: Welded Strips @ 300mm]
    B --> J[Sealants to Prevent Water Ingress]

This summary ensures durable joints controlling cracking and maintaining pavement integrity.

Quality Control in Concrete Pavement (MORD 26)

Key Quality Tests after Construction (Clause 17.0)

• Destructive Testing:

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

• Non-Destructive Testing:

  • Visual inspection for defects: blow-ups, corner breaks, cracks, faulting, pumping.
  • Benkel Beam Deflection Test:
    • Measures pavement deflection under load.
    • Deflection measurement points:
      • 0.9 m from edge for main roads (width 5.5 m).
      • 0.6 m from edge for other roads (width 3.75 m).
    • Measurements taken every 100 m along the pavement.

Additional Notes:

• Regular testing ensures durability and performance.
• Visual checks help identify surface distress early.
• Deflection tests assess load-bearing capacity and structural health.

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

For detailed mix design, curing, and joint specifications, refer to the respective sections in MORD 26 Table of Contents (Pages 6-11).

Key Specifications & Methods for Curing (MORD 26)

Clause 3.5 Highlights:

• Due to 3 to 3.5% camber on rural roads, wet jute/coir mats or wet paddy straw (Fig. 10) are effective for curing.
• These materials retain moisture better than ponding, allowing light traffic during curing.
• Ponding causes water to accumulate on the lower side; the higher side dries quickly.

Recommended Curing Methods

Practical Tips:

• Cover concrete immediately after finishing to prevent moisture loss.
• Maintain curing for at least 7 days for normal concrete.
• For hot weather, ensure continuous wetting or cover with wet mats/straw.
• Allow light traffic only after adequate curing to avoid surface damage.

Visual Concept (Curing by Wet Mats & Ponding)

flowchart LR
    A[Fresh Concrete Surface] --> B[Cover with Wet Jute/Coir Mats or Paddy Straw]
    B --> C[Maintain Continuous Moisture]
    A --> D[Water Ponding]
    D --> E{Cambered Surface?}
    E -- Yes --> F[Water runs off, uneven curing]
    E -- No --> G[Water retained, effective curing]

Summary:

• Use wet mats/straw for better moisture retention on cambered rural roads.
• Ponding is less effective due to runoff.
• Proper curing ensures strength gain and durability of concrete pavement.

For detailed mix design and construction, refer to clauses 26.5 and 8 of MORD 26 and IRC:44-2008.

Opening to Traffic - Key Points from MORD 26

• Curing & Early Traffic:

  • Use wet jute/coir mats or wet paddy straw for curing (3–3.5% camber on rural roads).
  • These methods allow light traffic on the surface during curing.
  • Ponding method less effective on cambered surfaces as water pools on lower side only.

• Traffic Opening Timing:

  • Light traffic can be allowed once initial curing with wet mats/straw is done (typically after 3-7 days depending on concrete strength gain).
  • Full traffic loading should wait until concrete attains sufficient strength (usually 28 days or as per design).

• Quality Control Before Opening:

  • Conduct Destructive Testing (core extraction and strength tests).
  • Perform Non-Destructive Testing (visual inspection for cracks, blow-ups, corner breaks).
  • Use Benkel Beam Deflection Test:
    • Deflection measured at 0.9m from edge for 5.5m wide roads
    • At 0.6m from edge for 3.75m wide roads
    • Measurements at 100m intervals to assess pavement readiness.

Summary Table: Opening to Traffic Criteria

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

This ensures safe opening to traffic minimizing damage risk.

Appearance of Top Surface - Key Points from MORD 26

• Visual Characteristics (Clause 13):

  • Plastic formwork outlines are visible on the pavement surface (Fig. 11).
  • For concrete thickness > 100 mm, 100 mm deep plastic cells may not be visible.
  • Cracks tend to form along plastic sheet joints after months of traffic, showing the formwork pattern.

• Curing Impact (Clause 3.5):

  • Camber of 3-3.5% helps water curing.
  • Wet jute/coir mats or wet paddy straw provide better curing and allow light traffic.
  • Ponding method causes uneven curing due to water accumulation on lower side.

• Aggregate Gradation Table (Clause 26.5):

  Sieve size (mm)	% Passing by weight
  26.50	100
  19	80-100
  9.50	55-80
  4.75	35-60
  0.60	10-35
  0.075	0-8

• Aggregate Quality:

  • Coarse aggregate impact value < 30 (IS:2386 Part 4).
  • Flakiness index < 40%.
  • Max size ≤ 26.5 mm.

Summary Diagram: Appearance & Curing Interaction

flowchart LR
    A[Plastic Formwork] --> B[Visible Outlines on Surface]
    B --> C[Crack Formation at Joints]
    D[Camber 3-3.5%] --> E[Better Water Curing]
    E --> F[Use of Wet Jute/Coir Mats or Paddy Straw]
    F --> G[Light Traffic Allowed]
    H[Ponding Method] --> I[Uneven Water Distribution]
    I --> J[Drying of Higher Surface]

Note: Proper curing and aggregate gradation ensure durable surface appearance and performance of flexible concrete pavements per MORD 26.

The Grouting Method for construction of flexible concrete pavement (Clause 14, MORD 26) involves filling preformed cells or voids with a grout mix to form a composite pavement.

Key Specifications & Steps:

• Plastic cells (typically 100 mm deep) are laid on the prepared subgrade/subbase.
• Cells are filled with cement grout or lean concrete to form a rigid base.
• Grout mix typically has a water-cement ratio of 0.4 to 0.5 for good flow and strength.
• Thickness of grout layer corresponds to cell depth (usually 100 mm).
• After grouting, the surface is finished smooth and cured properly (e.g., wet jute/coir mats or ponding).

Important Considerations:

• Ensure grout fluidity for complete filling without voids.
• Proper curing is critical to avoid shrinkage cracks.
• Pavement thickness (grout + overlay) is designed as per traffic load (refer Clause 15).

Typical Grout Mix Proportions:

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/Ponding)]
    E --> F[Open to Traffic]

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

Pavement Thickness of Flexible Concrete (Cell Filled Concrete Pavement)

Key Points from MORD 26 & IS Codes:

• Concrete Thickness:

  • Varies between 50 mm to 100 mm depending on traffic volume.
  • For low volume roads (<50 motorized vehicles/day), 100 mm thickness is recommended to ensure non-erodible support if subgrade CBR ≥ 5.

• Subbase Thickness:

  • Minimum 100 mm granular subbase (GSB) for 75 mm and 100 mm thick concrete layers.
  • Subbase thickness depends on cumulative standard axle load repetitions (refer to Figures 12 & 13 in MORD 26).
  • If GSB unavailable, use lime/cement stabilized soil or lime-fly ash stabilized soil.

• Aggregate Specifications (Clause 26.5):

  • Coarse aggregates: max size 26.5 mm, impact value < 30%, flakiness index < 40%.
  • Fine aggregates: clean natural sand or crushed stone.
  • Aggregate gradation (Table 1):

• Concrete Strength:
  • 28-day cube strength ~ 25 MPa or higher by grouting method.

Summary Table: Thickness Recommendations

Conceptual Diagram of Pavement Layers

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

References:

Advantages of Cell Filled Concrete Pavements (IS Code MORD 26, Clause 16.0):

• No expansion/contraction joints needed: Eliminates joint maintenance.
• Cost-effective: Construction cost is considerably lower than conventional cement concrete (CC) pavements.
• Aggregate saving: Aggregate consumption reduced by ~50% compared to normal CC pavements.
• Reduced pavement thickness: High stiffness allows thinner crust, economical for low-volume roads.
• Easy block replacement: Damaged individual blocks can be replaced with minimal effort and cost.
• Use of recycled plastic: Environmentally friendly by incorporating plastic cells.

Summary Table of Key Benefits

Note:

• Cell preparation and concrete placement require care to avoid disturbance.
• Construction is labor-intensive and slower than normal methods.

flowchart LR
    A[Use of Plastic Cells] --> B[Reduced Aggregate Usage]
    B --> C[Lower Construction Cost]
    A --> D[No Expansion Joints]
    D --> E[Maintenance Free Joints]
    C --> F[Economical Pavement Thickness]
    F --> G[Suitable for Low Volume Roads]
    E --> H[Longer Pavement Life]
    A --> I[Easy Block Replacement]

This concise summary captures the key advantages per MORD 26 Clause 16.0 for cell filled concrete pavements.

Quality Tests after Construction (MORD 26, Clause 17.0)

1. Destructive Testing:

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

2. Non-Destructive Testing:

   • Visual inspection for defects like blow-ups, corner breaks, cracks, faulting, and pumping.

3. Benkel Beam Deflection Test:

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

Summary Table: Deflection Measurement Points

Note: Core extraction and Benkel Beam tests ensure pavement quality and structural adequacy post-construction. Visual checks help detect surface defects early.

flowchart LR
    A[Post-Construction Quality Tests] --> B[Destructive Testing]
    A --> C[Non-Destructive Testing]
    A --> D[Benkel Beam Deflection Test]
    B --> E[Core Extraction & Testing]
    C --> F[Visual Inspection for Defects]
    D --> G[Deflection Measurement at 0.9m or 0.6m]
    G --> H[Every 100m Interval]

This approach ensures comprehensive pavement quality validation.