Code of practice for construction of lightweight concrete block masonry

IS 6042: Scope Summary & Key Specifications

• Scope: Covers specifications for load-bearing lightweight concrete blocks and lime-cement cinder solid blocks used in masonry walls.

• Information Required for Work Execution (Clause 3.1):

  • Layout plans with walls, doors, windows, stairs, columns.
  • Detailed dimensions and sectional details.
  • Architectural features and embedded fittings.
  • Embedded conduits, pipes, ducts.

• Programming of Work (Clause 4.3):

  • Time schedule including supply of drawings, material delivery, and construction timelines.

• Maintenance (Clause 12.1):

  • Annual pre-monsoon inspection.
  • Crack sealing with cement grout.
  • Two coats of cement paint on exposed walls.

Typical Specifications for Blocks (from IS 6042 context & general practice):

Work Planning Checklist (Clause 3.1 & 4.3)

flowchart TD
    A[Start: Project Planning] --> B[Prepare Layout Plans]
    B --> C[Provide Structural Dimensions]
    C --> D[Detail Architectural Features & Embedded Items]
    D --> E[Schedule Material Delivery & Construction]
    E --> F[Execute Masonry Work]
    F --> G[Annual Maintenance & Inspection]

Note: For detailed block dimensions, mix proportions, and testing methods, refer to full IS 6042 standard text or related IS codes on masonry units.

IS 6042: Key Definitions & Specifications

1. Definitions (Clause 2.4)

• Moisture Movement:
  Difference in length between a specimen dried to constant length and when saturated with water, expressed as % of dry length.
  [ \text{Moisture Movement (%)} = \frac{L_{\text{wet}} - L_{\text{dry}}}{L_{\text{dry}}} \times 100 ]

2. Necessary Information for Work (Clause 3.1)

• Layout plans: walls, doors, windows, stairs, columns.
• Detailed structural dimensions & sections.
• Architectural features and embedded fittings.
• Embedded conduits, pipes, ducts details.

3. Avoidance of Crack Formation - Joint Reinforcement Spacing (Clause 7.5.5.3)

Summary Diagram: Joint Reinforcement Spacing

graph LR
A[Wall Panel] --> B{Spacing of Joint Reinforcement}
B --> C[600 mm: L ≤ 12.5 m, L/H ≤ 2.5]
B --> D[400 mm: L ≤ 15 m, L/H ≤ 3]
B --> E[200 mm: L ≤ 18 m, L/H ≤ 4]

Note: Use these spacing limits to control cracking and ensure structural integrity in masonry walls.

IS 6042: Necessary Information & Key Specifications

Clause 3.1: Necessary Information for Work Planning

Provide detailed data to ensure efficient design and execution:

• Layout Plans: Show walls, doors, windows, openings, stairs, columns.
• Dimensions: Detailed structural dimensions and sectional details.
• Architectural Features: Mouldings, fittings, and embedded items in masonry.
• Embedded Services: Electrical conduits, sanitary/water pipes, air-conditioning ducts.

Clause 2.4: Moisture Movement

• Moisture movement = (Length saturated - Length dry) / Length dry × 100%
• Expressed as % of dry length, critical for dimensional stability.

Clause 7.5.5.3: Vertical Spacing of Joint Reinforcement (Avoiding Cracks)

• Use closer spacing for higher crack control.

Summary Diagram: Information Flow for Masonry Work

flowchart TD
    A[Start: Project Planning] --> B[Gather Layout Plans]
    B --> C[Collect Structural Dimensions]
    C --> D[Detail Architectural Features]
    D --> E[Specify Embedded Services]
    E --> F[Design Joint Reinforcement]
    F --> G[Execution & Monitoring]

This ensures compliance with IS 6042 for load-bearing masonry blocks and crack prevention.

IS 6042: Preparatory Work Key Points

1. Detailed Information for Planning (Clause 3.1)

• Layout plans: Walls, doors, windows, openings, stairs, columns.
• Dimensions: Structural sections and sizes.
• Architectural details: Mouldings, fittings, special embedded work.
• Embedded services: Electrical conduits, water pipes, air ducts.

2. Material Storage & Handling (Clause 8.2)

• Cement, lime, aggregates stored/handled per relevant IS codes (e.g., IS 269 for cement).

3. Mortar Preparation (Clause 6.3)

• Mortar per IS 2250:1965.
• Mortar slump: 75 mm (IS 1199:1959 test method).

4. Work Programming (Clause 4.3)

• Schedule must include:
  • Drawing/specification supply dates.
  • Material delivery dates.
  • Start and finish dates for masonry operations.

Useful Reference Table: Mortar Mix Proportions (from IS 2250)

flowchart TD
    A[Start Preparatory Work] --> B[Collect Layout Plans & Dimensions]
    B --> C[Identify Architectural & Embedded Details]
    C --> D[Schedule Material Delivery & Work Phases]
    D --> E[Store Materials as per IS Codes]
    E --> F[Prepare Mortar per IS 2250]
    F --> G[Begin Masonry Construction]

This structured approach ensures compliance with IS 6042 and smooth masonry execution.

IS 6042: Key Specifications & References for Materials

1. Materials Storage & Handling (Clause 8.2)

• Cement, lime, aggregates, and other masonry materials must be stored and hauled per relevant IS standards (e.g., IS 269 for cement, IS 1542 for lime).

2. Mortar Preparation (Clause 6.3)

• Mortar must follow IS 2250:1965 (Code of Practice for preparation and use of masonry mortars).
• Mortar slump: 75 mm as per IS 1199:1959 (testing method).

3. Relevant Material Specifications

• Building limes: Refer to revised specifications.
• Aggregates: Use IS 383 (coarse & fine aggregates for concrete).
• Sand for masonry mortars: IS 2116.
• Pozzolanic materials like fly ash and burnt clay pozzolana have specific IS standards.

4. Design Considerations for Joint Reinforcement (Clause 7.5.5.3)

Summary:

• Follow IS 2250 for mortar mix & preparation.
• Maintain slump of 75 mm.
• Store materials per respective IS codes.
• Use joint reinforcement spacing from Clause 7.5.5.3 to avoid cracks.

flowchart TD
    A[Materials: Cement, Lime, Aggregates] --> B[Storage & Handling per IS]
    B --> C[Mortar Preparation per IS 2250]
    C --> D[Mortar Slump = 75 mm (IS 1199)]
    D --> E[Joint Reinforcement Spacing per Clause 7.5.5.3]
    E --> F[Avoid Crack Formation]

This ensures compliance with IS 6042 for durable masonry construction.

Mortar Specifications for Lightweight Concrete Blocks (IS 6042)

• Mortar Mix Ratios:

  • Normal conditions: 1:2:9 (Cement : Lime : Sand)
  • High load or severe exposure: 1:1:6 (Cement : Lime : Sand)
  • If good quality lime unavailable: 1:6 (Cement : Sand)

• Purpose: Mortar strength is kept lower than block strength to avoid cracking.

• Application Notes:

  • For exposed faces, rake out mortar to 20 mm depth and fill with caulking compound.
  • On unexposed faces, use caulking compound or mortar alternately.
  • 5 mm greased wires are laid in every alternate course for reinforcement.
  • Control joints and pilasters incorporate these wire reinforcements and caulking.

Summary Table: Mortar Mix for Lightweight Concrete Blocks

Control Joint & Reinforcement Details:

flowchart LR
    A[Exposed Face] --> B[Rake out mortar 20 mm]
    B --> C[Fill with Caulking Compound]
    D[Unexposed Face] --> E[Alternate courses with mortar or caulking]
    F[Every alternate course] --> G[5 mm greased wire reinforcement]
    G --> H[Wire bent in U-shape for pilasters]

Reference: IS 6042 Clauses 6.2, 10.1.1, and control joint figures.
Block Density: ≤ 1000 kg/m³ as per IS 3590-1966.

IS 6042: Structural Requirements & Design Considerations

1. Bond Beams and Studs as Structural Members (Clause 7.3)

• Bond beams can be structural or non-structural.
• Non-structural bond beams provide continuous tension resistance (Clause 7.3.5).
• Structural bond beams/studs must be designed to carry loads and resist bending/tension.

2. Avoidance of Crack Formation (Clause 7.5.5.3)

• Vertical spacing of joint reinforcement depends on wall panel dimensions and crack control requirements.

• Use closer spacing for higher crack control (smaller spacing → higher crack resistance).

3. Lateral Supports (Clause 7.2.3.1)

• Provide horizontal or vertical lateral supports at right angles.
• Supports include:
  • Cross-walls
  • Pilasters
  • Sealed bonds
  • Buttresses
  • Floors and roofs (vertical support)
• Limiting distances for supports must be controlled to avoid buckling.

Summary Table: Key Design Parameters

flowchart TD
    A[Wall Panel] --> B[Joint Reinforcement Spacing]
    B -->|200 mm| C[Max Length 18 m, L/H=4]
    B -->|400 mm| D[Max Length 15 m, L/H=3]
    B -->|600 mm| E[Max Length 12.5 m, L/H

IS 6042: Storage and Handling of Masonry Materials

Key Specifications (Clause 8)

• Storage of Blocks (8.1):

  • Store blocks off the ground on planks or supports.
  • Protect blocks from moisture by covering with waterproof sheets.
  • Avoid direct contact with water or damp surfaces to prevent weakening.

• Storage of Cement, Lime, Aggregates (8.2):

  • Follow relevant IS codes for each material (e.g., IS 269 for cement).
  • Store in dry, covered areas with proper stacking to avoid contamination or moisture ingress.

Control Joints (Clause 7.5.6.2)

Control joints are essential to accommodate movement and prevent cracking in masonry walls:

Summary Diagram

flowchart TD
    A[Storage of Blocks] --> B[Off Ground on Planks]
    B --> C[Covered to Prevent Moisture]
    A --> D[No Contact with Ground]
    E[Control Joints] --> F[Changes in Wall Height/Thickness]
    E --> G[Construction Joints]
    E --> H[Recesses/Chases]
    E --> I[Abutments of Walls/Columns]
    E --> J[Return Angles]
    E --> K[Wall Openings]

Note: For exact stacking heights, spacing, and handling equipment, refer to IS 269 (Cement), IS 383 (Aggregates), and IS 2185 (Concrete Blocks).

IS 6042: Preparatory Work Key Points

1. Information for Planning (Clause 3.1)

• Layout plans: Walls, doors, windows, openings, stairs, columns.
• Dimensions: Detailed structure dimensions and section details.
• Architectural details: Mouldings, fittings embedded in masonry.
• Embedded services: Electrical conduits, sanitary pipes, water supply, AC ducts.

2. Material Storage & Handling (Clause 8.2)

• Cement, lime, aggregates, masonry materials stored/transported per relevant IS codes (e.g., IS 269 for cement).

3. Mortar Preparation (Clause 6.3)

• Mortar per IS 2250:1965.
• Slump: 75 mm (IS 1199:1959 test method).

4. Work Scheduling (Clause 4.3)

• Schedule includes:
  • Drawing/specification delivery.
  • Material and masonry unit delivery.
  • Start and completion dates for construction phases.

Essential Reference Codes:

flowchart TD
    A[Preparatory Work] --> B[Layout Plans]
    A --> C[Material Storage]
    A --> D[Mortar Preparation]
    A --> E[Work Scheduling]
    B --> B1[Walls, Doors, Windows]
    B --> B2[Sections & Dimensions]
    B --> B3[Embedded Services]
    D --> D1[IS 2250 Mortar Mix]
    D --> D2[Slump 75 mm]
    E --> E1[Drawings & Specs]
    E --> E2[Material Delivery]
    E --> E3[Construction Timeline]

This ensures efficient, compliant masonry work per IS 6042 guidelines.

IS 6042 – Operations for Laying Block Masonry (Clause 10.2)

Key Specifications & Practices:

• Mortar Mix:

  • Lightweight concrete block masonry shall be laid in:
    • 1:2:9 (cement:lime:sand) or
    • 1:1:6 (cement:lime:sand) mortar (Clause 10.1.1)
  • If lime quality is poor, use 1:6 cement-sand mortar.

• Alignment:

  • Stretch a mason’s line from corner to corner for each course.
  • Lay the top outside edge of each block to this line (Clause 10.2.3).
  • Handle blocks to minimize adjustments after placement.

• Control Joints & Reinforcement:

  • On exposed faces, rake out mortar joints to 20 mm depth and fill with caulking compound.
  • Use 5 mm greased wires laid in every alternate course for reinforcement.
  • Wires may be bent in "U" shape for pilasters and control joints (see Fig. 1 & 2).
  • On unexposed faces, fill joints with mortar or caulking compound alternately.

Summary Table: Mortar Mix for Block Masonry

Visual Concept (Control Joint & Wire Reinforcement):

flowchart LR
    A[Corner Blocks] --> B[Mason's Line Stretched]
    B --> C[Blocks Laid to Line]
    C --> D[Alternate Courses with 5mm Greased Wire]
    D --> E[Exposed Face: Rake Mortar 20mm]
    E --> F[Fill with Caulking Compound]
    D --> G[Unexposed Face: Mortar or Caulking]

Note: Proper alignment and joint treatment ensure durability, reduce cracking,

IS 6042: Rendering and Other Finishes - Key Points

External Rendering (Clause 11.1 & 11.1.1)

• Purpose: Waterproof lightweight concrete block walls.
• Conditions: Apply only on dry walls, avoid monsoon.
• Plastering per IS:2402-1963 with graded sand (3 mm downwards).
• Finish: Coarse finish using wooden float.

Recommended rendering for heavy rainfall/sea exposure:

Internal Rendering (Clause 11.2)

• For exposed block surfaces: flush point + paint (cement, emulsion, chlorinated rubber).
• Avoid oil-based paints (alkali attack).
• For plastered finish:
  • 1 coat, 6-12 mm thick, 1:2:9 (cement:lime:sand) mortar.
  • Optional 2nd coat (2-3 mm) lime finish for smoothness.

Additional Notes

• Side walls of long buildings require pilasters or sealed bonds ~2× wall thickness for stiffening (Clause 10.6.3).
• Sand grading and plaster finish texture are critical for durability and aesthetics.

flowchart TD
    A[External Walls] --> B{Rainfall Intensity}
    B -->|Heavy/Sea Exposure| C[Two Coat Rendering]
    B -->|Light/Moderate| D[Single Coat or Paint]
    C --> E[Backing Coat: 15mm, 1:1:6 or 1:6 mortar]
    C --> F[Finishing Coat: 5-10mm, 1:1:6 to 1:2:9 mortar]
    D --> G[Flush Point + Paint]

This ensures durability and waterproofing of lightweight concrete block masonry per IS 6042.