Recommended practice for quarrying stones for construction purposes

IS 8381: Scope Summary for Quarrying Stones for Construction

Scope:

• Recommended practices for quarrying stones used in construction.
• Covers methods for removing weathered rock overburden.
• Details on drilling, blasting, and handling stones.

Key Specifications & Practices (Clause 8.3)

• Overburden Removal:

  • Use compressed air hammer drills for hole drilling.
  • Employ shovels, bulldozers for clearing blasted rock.

• Blasting:

  • Choose explosives based on stone use:
    • High-grade explosives for extreme fragmentation.
    • Low detonation rate explosives where fines are undesirable (e.g., lime burning).

• Post-Blasting Handling:

  • Load blasted stone into trucks/loaders.
  • Transport to stacking yard for further processing.

Practical Notes

Visualization: Quarrying Process Flow

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

For detailed tables on explosives and stone types, refer to full IS 8381 text.

IS 8381: Terminology and Definitions - Key Points

IS 8381 (1977) covers terminology related to stone materials in construction. While the code does not list explicit formulas, it defines terms essential for understanding stone processing and use.

Key Definitions (Common in IS 8381 context):

• Crushed Stone: Stone broken into specified sizes by mechanical means.
• Broken Stone: Stone fragmented by blasting or mechanical crushing.
• Natural Stone: Stone obtained by quarrying without mechanical crushing.
• Weathered Rock Overburden: Surface rock layer removed before quarrying sound stone.

Important Notes from Clause 8.3 (Stone Preparation):

• Weathered rock removed by drilling and blasting.
• Explosive choice depends on stone use; high detonation explosives for fragmentation, low detonation to avoid fines.
• Post-blasting, stone is loaded and transported for stacking or processing.

Typical Terminology Table (Illustrative):

Summary Diagram: Stone Quarrying Process

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

For detailed definitions, refer to IS 8381 full text. This summary aids understanding of stone terminology and quarrying steps per the code.

IS 8381: Quarrying Methods - Key Points & Specifications

Quarrying Process (Clauses 7.2, 8.1, 8.2)

• Overburden removal → primary cuts → block lifting → subdivision by drilling & wedging.
• Blasting: Use minimal explosives to create fractures only; avoid heavy charges to prevent excessive breakage.
• Open pit mining is common:
  • Flat beds: enlarge pit laterally.
  • Thick beds: deeper, narrower pits with less stripping.
  • Steep beds: deep quarrying with increased waste removal and possible dewatering.
• Manual methods: crowbars, hammers, wedges for fissured rock or large boulders.
• Riverbed materials: controlled water flow and ring bands to quarry limited depth.

Important Specifications:

Practical Tips:

• Avoid over-blasting to reduce waste and maintain block integrity.
• Adjust quarry shape based on geological conditions to optimize cost.
• Dewatering may be necessary for deep or water-logged quarries.

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

This guide aligns with mining department practices and is ideal for new quarry operations.

IS 8381: Primary Cuts and Block Extraction Key Points

Primary Cuts (Clauses 4.2, 6.3)

• Purpose: Separate block from parent rock using natural joint planes.
• Method:
  • Use natural joints if available.
  • If absent, drill holes and use minimal gunpowder charge to cause fracture without shattering.
  • In large quarries, use a channeling machine to cut a narrow trench (~5 cm wide).
  • In small quarries, light blasting or wedging may be used after initial fracture.

Floor Breaking (Clause 4.4)

• Separate block from bottom using:
  • Natural horizontal parting planes.
  • If absent, drive wedges into horizontal drill holes at block base to break floor.

Quarrying Sequence (Clause 7.2)

1. Remove overburden.
2. Make primary cuts.
3. Lift block from bottom.
4. Subdivide block by drilling and wedging.
5. Use minimal gunpowder to avoid shattering.

Typical Drill Hole & Wedge Setup (schematic):

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 Tips:

• Drill hole diameter: ~30-50 mm (typical for gunpowder charges).
• Gunpowder charge: Just enough to cause fracture (avoid overcharging).
• Channel width by machine: ~5 cm.
• Wedge spacing depends on block size; typically 0.5-1 m apart.

This ensures controlled extraction minimizing damage to blocks.

Drilling and Blasting Techniques in Marble Quarry (IS 8381)

Key Specifications:

• Drilling Holes for Channels (Clause 3.4):

  • 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 (depends on natural joints)
  • Limited number of holes blasted at a time with undercharged explosives to avoid cracks

• Loosening the Block (Clause 3.5):

  • Single hole diameter: 4 to 5 cm
  • Location: Intersection of joints perpendicular to strike and channel (see Fig. 1)
  • Hole depth: 30 to 35 cm less than channel depth (to protect underlying block)
  • Charge: Undercharged with gunpowder for controlled loosening

• Blasting (Clause 8.2):

  • Heavy charges for breaking rock after drilling
  • Manual tools (crowbars, hammers, wedges) used for fissured rock or large boulders

Summary Table

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

This method ensures controlled blasting minimizing damage to marble blocks.

IS 8381: Site Selection & Overburden Removal Key Points

Site Selection

• Choose locations with minimal overburden and good quality mineral beds underneath.
• Avoid areas with important geological features or marble beds of good quality.

Overburden Removal (Clauses 3.3, 6.2, 7.2)

• Manual or mechanical removal: Manual labour or compressed air drills for drilling holes.
• Blasting: Used only in hard strata; holes ~2.5 cm diameter, 0.5 to 0.7 m depth.
• Waste disposal: Transport waste rock away from mineral zones; use power shovels, dumpers.
• Free faces opening:
  • Channels cut by drilling and blasting.
  • Channel width: 0.6 to 0.8 m.
  • Channel depth: 3 to 6 m, depending on natural joints.
  • Length depends on joint spacing along and across strike.
• Blasting control: Use minimal explosives to avoid cracks in blocks.

Summary Table

flowchart TD
    A[Site Selection] --> B[Overburden Removal]
    B --> C[Manual/Mechanical Drilling]
    B --> D[Blasting (Controlled)]
    D --> E[Open Free Faces]
    E --> F[Channel Cutting (0.6-0.8 m width)]
    F --> G[Block Extraction]
    B --> H[Waste Rock Disposal]

This ensures efficient, safe quarrying with minimal damage to valuable stone blocks.

IS 8381: Block Handling and Subdivision Key Points

1. Block Subdivision (Clauses 3.7 & 6.6)

• Method: Drill holes along the desired splitting line, aligned with the marble's rift or grain for easier splitting.
• Process: Insert wedges into drilled holes and hammer to split the block into smaller sizes.
• Hoisting: Subdivided blocks are hoisted and transported to stacking yards.

2. Floor Breaking (Clause 4.4)

• Purpose: Separate the block from the base.
• Technique: Use natural horizontal parting planes if available.
• Alternative: Drill horizontal holes at the block base, insert wedges, and drive them to break the floor.

3. Dressing and Transport (Clause 3.7.1)

• Blocks are dressed with chisels and hammers to achieve rectangular shape.
• Lifted manually or by mechanical cranes, then transported for processing.

Summary Table: Block Subdivision Steps

flowchart TD
    A[Big Marble Block] --> B[Drill Holes along Rift/Grain]
    B --> C[Insert Wedges]
    C --> D[Hammer Wedges to Split]
    D --> E[Separate Block from Base (Floor Breaking)]
    E --> F[Dress Blocks to Rectangular Shape]
    F --> G[Hoist and Transport to Yard/Factory]

This method ensures efficient and controlled subdivision, minimizing wastage and damage.

IS 8381 – Key Points on Crushed, Broken, and Natural Stone

Types of Stones (Clause 8.0)

• Common varieties: Limestone, Granite, Sandstone, Gneiss, Quartzite, Trap
• Used primarily for crushed and broken stone aggregates.

Quarrying Process (Clause 7.2)

• Overburden removal → Primary cuts → Block lifting → Subdivision by drilling and wedging.
• Use minimal gunpowder charge to create fractures without excessive breakage.

Specifications & Guidelines

• Stones must be hard, durable, and free from weathering.
• Crushed stone size typically ranges from 20 mm down to dust depending on use.
• Natural stone should be sound, dense, and free from cracks.

Typical Properties to Check

Key Formula for Crushing Strength (Approximate)

[ \text{Crushing Strength} = \frac{\text{Load at failure (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[Crushed/Broken Stone Production]

Summary: IS 8381 emphasizes proper quarrying techniques and selection of durable stone types to ensure quality crushed and natural stone for construction.

IS 8381 - Mechanized Quarrying Methods: Key Points

Quarrying Process (Clauses 7.2 & 8.2)

• Overburden removal → Primary cuts → Block lifting → Subdivision by drilling and wedging.
• Blasting: Use minimal explosives to create fractures without excessive breakage.
• Manual methods (crowbars, hammers, wedges) used only for fissured rock or large boulders.
• Mechanized loading and conveying to crushers for sizing.

Wire Saw Method (Clause 3.9)

• Uses 1 or 3 strand wire ropes (10 mm dia.).
• Abrasive cutting with sand and water fed continuously.
• Suitable for marble and similar stones.

Important Specifications

General Notes

• Mechanization improves efficiency and reduces manual labor.
• Careful control of blasting prevents wastage.
• Wire saw method is preferred for precision cutting in dimension stone quarries.

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

This concise guide aligns with IS 8381's recommendations for mechanized quarrying.

IS 8381 primarily guides quarrying operations, with limited direct details on Processing and Finishing of Stone Blocks. Based on standard practices and engineering knowledge, key points are:

Processing & Finishing of Stone Blocks

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

Typical Finishing Methods

Important Specifications

• Block Size: Depends on quarry and transport; typically 1-3 m³.
• Drill Hole Diameter: 25-35 mm for wedging.
• Wedge Spacing: 30-50 cm for controlled splitting.

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

For detailed finishing techniques, refer to IS 1121 (Methods of test for stones) and IS 3495 (Tests for natural stones).

IS 8381 covers Recommended Practices for Quarrying Stones for Construction Purposes but does not explicitly provide detailed formulas or tables for Safety and Environmental Practices. However, key recommendations based on standard quarrying safety and environmental norms include:

Safety Practices

• Protective Gear: Use helmets, gloves, goggles, and safety boots.
• Equipment Maintenance: Regular inspection and maintenance of machinery.
• Safe Blasting: Controlled blasting with clear demarcation of danger zones.
• Training: Skilled operators and safety drills.
• Emergency Preparedness: First aid and evacuation plans.

Environmental Practices

• Waste Management: Proper disposal and recycling of quarry waste.
• Dust Control: Water spraying and dust extraction systems.
• Noise Control: Use of silencers and restricted blasting times.
• Rehabilitation: Progressive backfilling and afforestation of exhausted areas.

Typical Safety Parameters (General Reference)

flowchart TD
    A[Quarrying Operation] --> B[Safety Measures]
    A --> C[Environmental Controls]
    B --> D[Protective Equipment]
    B --> E[Blasting Safety]
    C --> F[Dust Control]
    C --> G[Waste Management]
    C --> H[Site Rehabilitation]

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