Guidelines on Compaction Equipment for Road Works
2013 Edition

IRC SP 97 delineates the specifications for compaction of soils, bituminous layers, and concrete in roadworks. It provides directives on selecting, operating, and maintaining compaction machines for effective pavement construction.

Highlights & Reference Tables

1. Roller Selection According to Layer Thickness (Table 9)

2. Roller Preferences for Bituminous Layers (Table 10)

Summary Points

• Static rollers are favored for thin or initial layers.
• Vibratory rollers suit thicker layers and special soils.
• Pneumatic rollers apply to intermediate compaction.
• Tandem rollers primarily finish bituminous surfaces.

IRC SP 97 categorizes rollers based on their design and function:

• Three-wheeled rollers: static operation.
• Tandem rollers (two drums), including:
  • Sheepsfoot rollers
  • Tamping foot rollers
  • Pneumatic tyred rollers
  • Vibratory rollers (single and double drum variants)

Roller Selection by Layer and Work Type

Selection by Soil and Work Type

Roller Selection by Soil Type for Embankments/Subgrade

Fundamental Formulas, Tables & Specifications for Soil Compaction (IRC SP 97, Clause 7.1)

1. Soil Properties Affected by Compaction:

• Settlement: Compaction densifies soil, reducing settlement and preventing moisture infiltration.
• Strength: Increased density enhances bearing capacity.
• Permeability: Voids decrease, lowering permeability.
• Volume Change: Controls shrink-swell behavior.

2. Roller Suitability by Soil Type (Table 7):

3. Equipment & Passes per Soil Type (Table 8):

4. Compaction Mechanisms:

• Impact: High force, brief duration (e.g., rammers)
• Pressure: Force per area (e.g., static rollers)
• Vibration: Oscillating force (e.g., vibratory rollers)
• Kneading: Particle rearrangement (e.g., pneumatic rollers)

Practical Recommendations:

• Align compaction equipment with soil type for effectiveness.
• Fine-grained soils require thinner layers and more passes.
• Coarse soils tolerate thicker lifts with fewer passes.
• Correct compaction enhances pavement longevity and load resistance.

IRC SP 97: Overview of Compaction Machines

Compaction Mechanisms (Clause 3)

• Impact: Sudden, high force blows
• Pressure: Static force over contact area
• Vibration: Oscillatory shaking
• Kneading: Soil particle rearrangement

Equipment Types and Their Mechanisms (Table 1)

Key Equipment (Clause 4)

• Rammer: Impact and vibration, suited for cohesive soils.
• Vibratory Plate Compactor: Combines impact and vibration, ideal for granular soils.
• Rollers: Various types (static, pneumatic, vibratory) offering pressure, vibration, and kneading effects.

Summary

• Choose compaction equipment according to soil characteristics and mechanism required.
• Vibratory rollers provide versatility across soil types due to combined mechanisms.
• Proper compaction enhances strength, stability, and reduces permeability.

Choosing Compaction Machinery Based on Soil Characteristics
(IRC SP 97, Clauses 7.1 & 11.4)

1. Roller Recommendations by Soil Category (Table 12)

2. Equipment Parameters by Material (Tables 7 & 8)

3. Effects on Compaction (Clause 7.1)

• Settlement: Densification prevents pavement cracking.
• Strength: Increased load-bearing capacity.
• Permeability: Reduced through void minimization.
• Volume Change: Controlled shrink-swell behavior.

Summary

• Vibratory rollers best suited for granular and uniformly graded soils.
• Sheepsfoot rollers preferred for clays and silts due to kneading action.
• Adjust lift thickness and number of passes per soil type for optimal compaction.

Key Specifications for Bituminous Mix Compaction (IRC SP 97)

1. Factors Influencing Bituminous Compaction (Clause 5.2)

• Compactive Effort:

  • Increased roller weight and longer contact time improve compaction.
  • Shear stress generated by roller speed rearranges aggregate.
  • Lower roller speeds produce higher shear stress, enhancing compaction.

• Temperature:

  • Bitumen viscosity rises as temperature drops, reducing compaction.
  • The "cessation temperature" marks the limit below which compaction ceases.
  • Compaction time depends on cooling from mixing to cessation temperature.

• Roller Speed:

  • Slow, steady speeds promote uniform compaction.
  • Excessive speed decreases compactive effort.

2. Temperature Ranges (Table 5)

3. Typical Roller Speeds (Table 6)

4. Compaction Time Considerations

• The available time for compaction equals the interval between mixing and reaching the cessation temperature.

Principal Factors Impacting Soil Compaction (IRC SP 97, Clause 7.2):

1. Compactive Effort:

   • Energy applied per soil volume directly affects compaction efficiency.
   • Higher compactive effort leads to increased dry density and reduced permeability.

2. Soil Type and Moisture Content:

   • Maximum dry density achieved at optimum moisture content (Proctor curve).
   • Clayey soils require kneading and confinement; sandy soils respond better to vibration.

3. Equipment Suitability:

   • Table 7 indicates roller effectiveness:

• Table 8 specifies lift thickness, passes, and compactor types:

Compaction Process Overview

flowchart LR
    A[Soil Type & Moisture Content] --> B[Select Appropriate Equipment]
    B --> C[Apply Compactive Energy]
    C --> D[Achieve Target Dry Density]
    D --> E{Improved Soil Properties}
    E --> F[Reduced Settlement]
    E --> G[Enhanced Strength]
    E --> H[Lowered Permeability]

Note: Correctly matching soil properties, moisture, and compaction equipment ensures efficient compaction, improved pavement support, and durability.

Standards for Compaction of Shoulders and Joints (IRC SP 97):

1. Shoulder Compaction (Clause 9.1)

• Shoulders are constructed in layers matching the adjoining pavement thickness.
• The compaction sequence is pavement layer, paved shoulder layer, then earth shoulder layer.
• For different materials, compact pavement layers first, then shoulder layers.
• For uniform materials, compact pavement and shoulder layers simultaneously.
• Existing shoulders must be excavated fully before paving.

2. Longitudinal Joint Compaction (Clause 8.2)

• Types:

  • Hot Joint: Adjacent lanes paved in sequence while still hot; produces dense, seamless joints.
  • Cold Joint: Second lane paved after first lane cools; weaker, prone to cracking.

• Compaction Methods:

  • Rolling from Hot Side: Roller overlaps joint by ~150 mm onto cold mat, pushing mix toward joint for improved density.
  • Rolling from Cold Side: Less efficient; mix cools and compaction is harder.

Joint Compaction Summary Table

flowchart LR
    PavementLayer --> CompactPavementLayer
    CompactPavementLayer --> PavedShoulderLayer
    PavedShoulderLayer --> CompactPavedShoulderLayer
    CompactPavedShoulderLayer --> EarthShoulderLayer
    EarthShoulderLayer --> CompactEarthShoulderLayer

Note: Proper sequencing and temperature control are vital for joint strength and shoulder stability.

Roller Operation Guidelines (IRC SP 97)

1. Roller Selection for Maintenance Tasks (Clause 11.6, Table 13)

2. Roller Capacity Calculation (Clause 4.3.4)

[ \text{Compaction Area (m}^2/\text{hr)} = C \times W \times S \times T ]

• C: Constant (0.5-0.6 for bituminous, 0.75 for soil)
• W: Roller width (m)
• S: Rolling speed (km/h)
• T: Compact layer thickness (m)

3. Pneumatic Tyred Roller Details (Clause 3.0)

• Tire Pressure: Maintain between 2 to 9 kg/cm²; pressure below 2 kg/cm² damages tires and pavement.
• Tire Types:
  • Flat/Wide Base (approx. 0.4 MPa) for surface sealing.
  • Diagonal tires (0.3-0.9 MPa) for durability.
  • Radial tires preferred for bituminous applications.
• Tire Overlap: Front and rear tires overlap by 30-50 mm for uniform compaction.
• Oscillating Axle: Provides kneading action to enhance sealing and surface finish.

4. Ground Contact Pressure Table

Vibratory Plate Compactors Overview (IRC SP 97, Clauses 4.2 & 11.5)

Specifications:

• Frequency Range: 2500 to 6000 vibrations per minute (vpm)
• Weight Categories:
  • Light Compactors: less than 400 kg, high frequency, low amplitude
  • Heavy Compactors: more than 400 kg, lower frequency, higher amplitude
• Applications:
  • Light units for thin layers of coarse-grained soils, sand, gravel, and bituminous surfaces with water sprinklers
  • Heavy units for semi-cohesive soils, thicker layers, larger areas

Operating Principle:

• Vibrations produced by eccentric weights driven by gasoline or diesel engines.
• Engine and handle are vibration-isolated from the base plate.
• Reversible plates with two eccentric weights allow spot compaction, suitable for semi-cohesive soils.

Typical Usage:

• Embankments, sub-base, base courses, asphalt surfaces.
• Efficient for areas up to approximately 1000 m².

Parameter Summary:

Simplified Equipment Diagram:

graph LR
A[Engine] --> B[Eccentric Weight]
B --> C[Vibrating Base Plate]
A --> D[Handle with Vibration Isolation]
C --> E[Compaction Force Applied to Soil]

Note: Use water sprinklers on bituminous surfaces to prevent adhesion. Reversible plates facilitate targeted compaction.

Maintenance Guidelines for Compaction Equipment (IRC SP 97)

Though detailed maintenance clauses are limited, standard practices and Clause 12.3 for vibratory rollers offer these key points:

Daily Inspection Checklist:

• Check engine oil, hydraulic fluids, water in tanks, and fuel levels.
• Inspect vibratory system, including eccentric weights and bearings; lubricate as recommended.
• Clean drums regularly to prevent buildup; inspect for damage.
• Verify vibration frequency and amplitude settings match compaction requirements; adjust if necessary.
• Examine hydraulic hoses and connections for leaks.
• Follow manufacturer schedules for engine and transmission oil/filter changes.

Typical Vibratory Roller Parameters:

Maintenance Summary:

• Regular lubrication of moving parts.
• Tighten fasteners as needed.
• Replace worn components promptly.
• Store equipment sheltered to avoid corrosion.

flowchart TD
    A[Start Daily Inspection] --> B{Fluid Levels OK}
    B -- Yes --> C[Inspect Vibratory Components]
    B -- No --> D[Refill Fluids]
    C --> E{Drum Condition}
    E -- Clean --> F[Verify Vibration Settings]
    E -- Dirty/Damaged --> G[Clean or Repair Drum]
    F --> H[Check Hydraulic System]
    H --> I{Leaks Detected?}
    I -- Yes --> J[Repair Leaks]
    I -- No --> K[Perform Engine & Transmission Maintenance]
    K --> L[Complete Daily Maintenance]

Conclusion: Proactive maintenance enhances equipment efficiency, extends service life, and prevents operational interruptions.

Preventive Maintenance (PM) Essentials - IRC SP 97 Highlights

1. Definition (Clause 13.3)

• PM comprises scheduled servicing tasks conducted before equipment failure occurs.
• Purpose: To avoid frequent breakdowns of compaction machinery.
• Follow manufacturer-recommended spare parts replacement intervals.
• Maintain structured inspection and maintenance schedules.

2. Maintenance Types and Frequencies

3. Key Checks and Tasks

• Daily: Oil and water levels, V-belts, lubrication, leak detection, battery, gearbox oil.
• Semi-Annual: Oil filter and gearbox oil changes, belt adjustment/replacement, bearing and motor checks.
• PM: Scheduled spare parts replacement and condition monitoring.

4. Best Practices

• Keep fast-moving spares in stock.
• Use formal inspection routines to reduce breakdowns.
• Regular cleaning facilitates maintenance.

Maintenance Flowchart

flowchart TD
    A[Equipment in Use] --> B{Condition Monitoring}
    B -- Normal --> C[Continue Operation]
    B -- Wear Signs --> D[Schedule Preventive Maintenance]
    D --> E[Inspect Bearings, Belts, Filters]
    E --> F{Defects Found?}
    F -- Yes --> G[Repair or Replace Components]
    F -- No --> H[Continue Monitoring]
    G --> I[Update Spare Inventory]
    I --> C
    H --> C

This diagram illustrates decision-making based on equipment condition assessments.

References and Bibliographic Sources for IRC SP 97

Primary References (Clause 13.3 & Reference Section)

• Manual for Construction and Supervision of Bituminous Works, IRC, 2001
• Construction Planning, Equipment and Methods, Puerifoy et al., Tata McGraw Hill
• Study Report on Compaction Equipment, RDSO, 2005
• Specifications for Road and Bridge Works, MORTH/IRC
• Online resources including:
  • pavementinteractive.org
  • intelligentcompaction.com
  • bomag.com

Preventive Maintenance Notes (Clause 13.3)

• Periodic inspection of bearings, belts, and filters.
• Replace spares based on supplier recommendations.
• Maintain inventory of critical parts.
• Aim to minimize equipment downtime.

Vibratory Roller Application Data (Table 11)

Preventive Maintenance Cycle Diagram

flowchart LR
    A[Equipment Inspection] --> B{Condition Good?}
    B -- Yes --> C[Continue Operation]
    B -- No --> D[Repair or Replace Parts]
    D --> E[Record Maintenance]
    E --> A

This concise guide aids understanding of the key sources and operational protocols for compaction equipment per IRC SP 97.