Recommended practice for quarrying stones for construction purposes
1977 Edition

Overview of IS 8381 Scope for Stone Quarrying

Scope Summary:

• Guidelines for quarrying stones used in construction projects.
• Procedures for removing weathered rock (overburden).
• Details on drilling, blasting, and stone handling.

Key Guidelines (Clause 8.3)

• Overburden Removal:

  • Employ compressed air hammer drills for hole drilling.
  • Use shovels and bulldozers to clear blasted material.

• Blasting Procedures:

  • Select explosives based on intended use:
    • High-energy explosives for extensive fragmentation.
    • Low detonation rate explosives where minimizing fines is critical (e.g., lime burning).

• Post-Blasting Handling:

  • Load fragmented stone onto trucks or loaders.
  • Transport to storage yards for further processing.

Equipment and Operations Summary

Process Flow Illustration

flowchart LR
    A[Drilling Holes] --> B[Blasting Rock]
    B --> C[Clearing Overburden]
    C --> D[Loading into Transport]
    D --> E[Transport to Stacking Yard]

Refer to the full IS 8381 document for detailed explosive and stone type tables.

Essential Terminology as per IS 8381 (1977)

This code defines important terms related to stone materials and quarrying processes, aiding comprehension of stone extraction and handling.

Key Definitions:

• Crushed Stone: Stone broken down to specified sizes using mechanical means.
• Broken Stone: Stone fragmented through blasting or crushing.
• Natural Stone: Stone quarried without mechanical crushing.
• Weathered Rock Overburden: Surface layer of decomposed rock removed prior to quarrying solid stone.

Highlights from Clause 8.3 (Stone Preparation):

• Overburden removed by drilling and blasting.
• Explosive selection depends on intended use; high detonation for fragmentation, low detonation to reduce fines.
• Post-blasting, stones are loaded and transported for further processing.

Terminology Table (Example):

Process Flow Diagram

flowchart TD
    A[Overburden Removal] --> B[Drilling Holes]
    B --> C[Blasting with Explosives]
    C --> D[Fragmented Stone]
    D --> E[Loading and Transport]
    E --> F[Stacking or Processing]

For full definitions, consult the complete IS 8381 standard.

Key Quarrying Techniques per IS 8381 Clauses 7.2, 8.1, 8.2

• Sequence: Overburden removal → primary cuts → block lifting → subdivision via drilling and wedging.
• Blasting: Utilize minimal explosives to produce fractures only; avoid excessive breakage.
• Open Pit Mining:
  • Flat beds: lateral expansion.
  • Thick beds: deeper, narrower pits with reduced stripping.
  • Steep beds: deep quarrying with enhanced waste removal and possible dewatering.
• Manual Methods: Use crowbars, hammers, wedges for fissured rock or large boulders.
• Riverbed Quarrying: Control water flow and use ring bands to limit depth.

Specifications Summary:

Practical Advice:

• Avoid excessive blasting to limit waste and preserve block quality.
• Shape quarry according to geological conditions for cost efficiency.
• Dewatering may be necessary in waterlogged or deep pits.

flowchart TD
    A[Begin: Overburden Removal] --> B[Primary Cuts]
    B --> C[Block Lifting]
    C --> D[Subdivision by Drilling and Wedging]
    D --> E[Minimal Blasting]
    E --> F[Loading and Transport]
    F --> G[Crushing and Sizing]

This approach is consistent with mining department standards and suits new quarry setups.

Key Points on Primary Cuts and Block Extraction (Clauses 4.2, 6.3)

Primary Cuts:

• Aim to detach blocks along natural joints.
• Utilize existing joints if present.
• Where absent, drill holes and use minimal gunpowder charges to fracture without shattering.
• Large quarries may employ channeling machines to cut narrow trenches (~5 cm wide).
• Smaller quarries may use light blasting or wedging after initial fracture.

Floor Breaking (Clause 4.4):

• Separate block from base using natural horizontal partings.
• Alternatively, drill horizontal holes at block base and insert wedges to break the floor.

Quarrying Steps (Clause 7.2):

1. Remove overburden.
2. Make primary cuts.
3. Lift block from base.
4. Subdivide block with drilling and wedging.
5. Use minimal gunpowder to prevent shattering.

Drill Hole & Wedge Setup Illustration:

flowchart LR
    A[Parent Rock] --> B[Primary Cut Drill Holes]
    B --> C[Gunpowder Charge]
    C --> D[Fracture Line]
    D --> E[Wedges in Floor Drill Holes]
    E --> F[Block Separation]

Practical Recommendations:

• Drill hole diameter: approximately 30-50 mm for gunpowder charges.
• Charges should be minimal, sufficient to cause fracture only.
• Channel width by machine: about 5 cm.
• Wedge spacing typically 0.5 to 1 meter depending on block size.

This method achieves controlled extraction with minimal damage.

Drilling and Blasting in Marble Quarrying (IS 8381)

Specifications:

• Channel Drilling (Clause 3.4):

  • Hole diameter: ~2.5 cm
  • Depth: 0.5 to 0.7 m
  • Channel width: 0.6 to 0.8 m
  • Channel depth: 3 to 6 m depending on natural joints
  • Blast limited number of holes at a time with undercharged explosives to prevent cracks

• Block Loosening (Clause 3.5):

  • Single hole diameter: 4 to 5 cm
  • Location: At joint intersections perpendicular to strike and channel
  • Depth: 30 to 35 cm shorter than channel depth to protect underlying block
  • Charge: Undercharged gunpowder for controlled loosening

• Blasting (Clause 8.2):

  • Use heavier charges to break rock after drilling
  • Manual tools (crowbars, hammers, wedges) used for fissured rock or large boulders

Summary Table

flowchart TD
    A[Remove Overburden] --> B[Expose Weakness Planes]
    B --> C[Open Free Faces]
    C --> D[Drill Channel Holes (2.5 cm)]
    D --> E[Blast Undercharged Holes]
    E --> F[Drill Loosening Hole (4-5 cm)]
    F --> G[Blast Loosening Hole with Gunpowder]
    G --> H[Block Loosened for Extraction]

This approach ensures precise blasting to protect marble blocks.

Site Selection and Overburden Removal Highlights (IS 8381)

Site Selection:

• Opt for locations with minimal overburden and high-quality stone beds.
• Avoid important geological formations or valuable marble layers.

Overburden Removal (Clauses 3.3, 6.2, 7.2):

• Removal can be manual or mechanical; compressed air drills assist hole drilling.
• Blasting used only in hard layers; holes approximately 2.5 cm diameter and 0.5–0.7 m depth.
• Waste rock transported away from mineral zones using power shovels, dumpers.
• Free faces opened by drilling and blasting channels.
• Channel dimensions:
  • Width: 0.6–0.8 m
  • Depth: 3–6 m depending on natural joints
  • Length varies with joint spacing.
• Controlled blasting minimizes block cracking.

Summary Table

flowchart TD
    A[Select Site] --> B[Remove Overburden]
    B --> C[Manual/Mechanical Drilling]
    B --> D[Controlled Blasting]
    D --> E[Open Free Faces]
    E --> F[Channel Cutting (0.6-0.8 m width)]
    F --> G[Extract Blocks]
    B --> H[Dispose Waste Rock]

This procedure promotes effective and damage-minimized quarrying.

Procedures for Handling and Dividing Blocks (IS 8381)

Block Subdivision (Clauses 3.7 & 6.6):

• Drill holes along the stone’s rift or grain direction to facilitate splitting.
• Insert wedges into the holes and hammer them to split the block into smaller pieces.
• Hoist subdivided blocks for transport to storage yards.

Floor Separation (Clause 4.4):

• Separate the block from its base using natural horizontal partings if present.
• Alternatively, drill horizontal holes at the block base, insert wedges, and drive them to break the floor.

Dressing and Transportation (Clause 3.7.1):

• Blocks are dressed using chisels and hammers to achieve rectangular shapes.
• Blocks are lifted manually or mechanically and transported to processing locations.

Summary Table

flowchart TD
    A[Large Block] --> B[Drill Holes Along Rift/Grain]
    B --> C[Insert Wedges]
    C --> D[Hammer Wedges to Split]
    D --> E[Separate Block from Floor]
    E --> F[Dress Blocks to Rectangular Shape]
    F --> G[Hoist and Transport]

This method ensures efficient block division with minimal waste.

IS 8381 Overview on Stone Types and Quarrying (Clause 8.0)

Stone Varieties:

• Common types: limestone, granite, sandstone, gneiss, quartzite, and trap rock.
• Mainly utilized for crushed and broken stone aggregates.

Quarrying Sequence:

• Remove overburden → primary cuts → lift blocks → subdivide by drilling and wedging.
• Employ minimal gunpowder charges to produce fractures without excessive breakage.

Quality Specifications:

• Stones should be hard, durable, and free from weathering.
• Crushed stone sizes typically range from 20 mm down to dust based on usage.
• Natural stones must be sound, dense, and free of cracks.

Typical Properties:

Crushing Strength Formula (Approximate):

[ \text{Crushing Strength} = \frac{\text{Failure Load (N)}}{\text{Cross-sectional Area (mm}^2)} ]

flowchart TD
    A[Overburden Removal] --> B[Primary Cuts]
    B --> C[Block Lifting]
    C --> D[Subdivision by Drilling & Wedging]
    D --> E[Production of Crushed/Broken Stone]

In summary, IS 8381 highlights suitable quarrying techniques and selection criteria to ensure high-quality crushed and natural stone for construction.

Mechanized Quarrying Methods as per IS 8381

Quarrying Process (Clauses 7.2 & 8.2):

• Sequence: overburden removal → primary cuts → block lifting → subdivision via drilling and wedging.
• Use minimal explosives to produce fractures without excessive breakage.
• Manual tools (crowbars, hammers, wedges) reserved for fissured rock or large boulders.
• Mechanized loading and conveying systems transport stone to crushers for sizing.

Wire Saw Method (Clause 3.9):

• Utilizes 1 or 3 strand wire ropes (diameter approx. 10 mm).
• Abrasive cutting employs sand and water continuously fed.
• Ideal for marble and similar dimension stones.

Specifications Summary:

Additional Notes:

• Mechanization enhances efficiency and reduces manual labor.
• Controlled blasting prevents wastage.
• Wire saw cutting offers precision for dimension stones.

flowchart TD
    A[Remove Overburden] --> B[Primary Cuts]
    B --> C[Block Lifting]
    C --> D[Subdivision by Drilling & Wedging]
    D --> E[Controlled Explosive Blasting]
    E --> F[Loading & Conveying]
    F --> G[Crushing & Sizing]

This summary reflects IS 8381’s recommendations for mechanized quarrying.

While IS 8381 mainly addresses quarrying operations, common engineering practices for processing and finishing stone blocks include:

Processing & Finishing Steps:

• Primary Cutting: After overburden removal, primary cuts isolate blocks.
• Block Lifting and Subdivision: Blocks are lifted and split using drilling and wedging methods.
• Blasting Control: Use minimal explosives to avoid unnecessary fracturing.

Common Finishing Methods:

Key Specifications:

• Block sizes generally range from 1 to 3 cubic meters depending on quarry and transport constraints.
• Drill hole diameters for wedging typically between 25 and 35 mm.
• Wedge spacing varies between 30 and 50 cm for controlled splitting.

flowchart TD
    A[Remove Overburden] --> B[Primary Cuts]
    B --> C[Block Lifting]
    C --> D[Drilling & Wedging]
    D --> E[Subdivision]
    E --> F[Processing & Finishing]
    F --> G[Hammered / Polished / Honed Surfaces]

For detailed finishing procedures, consult IS 1121 (Methods of test for stones) and IS 3495 (Tests for natural stones).

Though IS 8381 focuses on quarrying techniques, it implies adherence to safety and environmental best practices including:

Safety Measures:

• Use of personal protective equipment: helmets, gloves, goggles, safety boots.
• Routine maintenance and inspections of machinery.
• Controlled blasting with clear demarcation of hazardous zones.
• Training programs and safety drills for operators.
• Emergency preparedness including first aid and evacuation plans.

Environmental Controls:

• Proper disposal and recycling of quarry waste.
• Dust suppression using water sprays and extraction systems.
• Noise control through silencers and restricted blasting hours.
• Progressive rehabilitation including backfilling and afforestation of depleted areas.

Typical Safety Parameters (General Recommendations):

flowchart TD
    A[Quarrying Process] --> B[Safety Protocols]
    A --> C[Environmental Management]
    B --> D[Protective Equipment]
    B --> E[Blasting Safety]
    C --> F[Dust Control Methods]
    C --> G[Waste Handling]
    C --> H[Site Rehabilitation]

For detailed regulations, refer to DGMS guidelines and Environmental Protection Acts alongside IS 8381.