Guide for preparation and use of mud mortar in masonry

IS 13077 - Scope Summary & Key Specifications

• Scope: Covers field and laboratory testing of soil for suitability in masonry mud mortar.

• Field Test (Clause 7.1 & Annex B):

  • Soil is ground to fine powder, mixed with water to form plastic mass.
  • Form a ball ~80 mm diameter.
  • Dry in sun, check for shape retention and surface cracks.
  • If unsuitable, modify soil by mixing with sand/clay and retest (Clause 7.1.3).

• Referenced IS Standards (Annex A):

  IS No.	Title
  IS 2720 (Part 4) : 1986	Grain size analysis (2nd revision)
  IS 2720 (Part 5) : 1970	Liquid and plastic limits determination
  IS 2809 : 1972	Glossary of soil engineering terms
  IS 4326 : 1976	Earthquake resistant building design

• Key Test Parameters:

  • Soil plasticity (liquid/plastic limits)
  • Grain size distribution
  • Stability of soil ball on drying

Summary: IS 13077 guides soil suitability testing for masonry mortar by simple field tests and references detailed soil test methods (IS 2720 series) for comprehensive analysis.

flowchart TD
    A[Soil Sample] --> B[Grind to fine powder]
    B --> C[Mix with water to plastic mass]
    C --> D[Form 80 mm diameter ball]
    D --> E[Dry in sun]
    E --> F{Check shape & cracks}
    F -- Suitable --> G[Use soil for mortar]
    F -- Unsuitable --> H[Modify soil (add sand/clay)]
    H --> B

IS 13077 References Summary

• Annex A (Clause 2.1) lists essential Indian Standards related to soil testing and construction:

  • IS 2720 (Part 4): 1986 — Grain size analysis (2nd revision)
  • IS 2720 (Part 5): 1970 — Determination of liquid and plastic limits (1st revision)
  • IS 2809: 1972 — Glossary of soil engineering terms and symbols (1st revision)
  • IS 4326: 1976 — Earthquake resistant design and construction of buildings (1st revision)

• Clause 7.1.3: If soil is unsuitable, modify by mixing soils or adding sand/clay and repeat tests for stability.

• Annex B (Clause 7.1): Field test for soil suitability for masonry mud mortar:

  1. Grind soil to fine powder, mix with water to plastic mass.
  2. Form 80 mm diameter ball.
  3. Dry in sun, check for cracks or shape loss.

Key Notes:

• Use referenced IS codes for detailed soil testing procedures.
• Modify soil composition if initial tests fail.
• Field test ball method is a quick stability check.

flowchart TD
    A[Soil Sample] --> B[Grind to Fine Powder]
    B --> C[Mix with Water]
    C --> D[Form 80 mm Ball]
    D --> E[Dry in Sun]
    E --> F{Check Ball}
    F -->|No cracks, shape retained| G[Soil Suitable]
    F -->|Cracks, shape lost| H[Modify Soil Composition]
    H --> B

This flowchart summarizes the soil field test and modification cycle per IS 13077.

IS 13077: Definitions and Key Specifications

The code primarily deals with soil suitability for masonry mud mortar, emphasizing field tests and soil modification methods.

Key Definitions & Specifications:

• Soil Suitability Test (Clause 7.1.3):
  If soil is unsuitable, modify by mixing different soils or adding sand/clay, then repeat tests to check stability.

• Field Test Procedure (Annex B):

  1. Grind soil to fine powder, mix with water to plastic consistency.
  2. Form a ball ~80 mm diameter.
  3. Dry in sun, observe for shape retention and cracks.

• Referenced IS Codes (Clause 2.1 & Annex A):

  • IS 2720 (Part 4): Grain size analysis
  • IS 2720 (Part 5): Liquid & plastic limits
  • IS 2809: Glossary of soil engineering terms
  • IS 4326: Earthquake-resistant building design

Summary Table: Soil Test Ball Criteria

Practical Notes:

• Soil plasticity and grain size govern mortar quality.
• Modify soil composition based on test results to achieve durable mortar.

flowchart TD
    A[Collect Soil Sample] --> B[Grind to Fine Powder]
    B --> C[Add Water Gradually]
    C --> D[Form 80 mm Ball]
    D --> E[Sun Dry Ball]
    E --> F{Check Shape & Cracks}
    F -- No cracks --> G[Soil Suitable]
    F -- Cracks/Deformation --> H[Modify Soil Composition]
    H --> B

This flow ensures soil used for mud mortar is stable and suitable per IS 13077.

Selection of Clay for Mud Mortar (IS 13077)

Key Specifications (Clause 4.1)

• Grain Size Composition (by weight):

  • Clay: 18-22%
  • Silt: 40-45%
  • Sand: 30-40%

• Grain size analysis as per IS 2720 (Part 4): 1986.

Moisture Content for Workability (Clause 6.4)

• Total moisture content in prepared mortar: 35-40% by weight of soil before use.

Summary Table: Clay Selection for Mud Mortar

Additional Notes:

• Proper grain size ensures good binding and durability.
• Moisture content controls workability and setting.
• Testing methods for grain size and moisture are standardized under IS 2720.

flowchart LR
    A[Clay Sample] --> B[Grain Size Analysis (IS 2720 Pt 4)]
    B --> C{Composition}
    C -->|Clay 18-22%| D[Acceptable]
    C -->|Silt 40-45%| D
    C -->|Sand 30-40%| D
    D --> E[Mix with Water (35-40% moisture)]
    E --> F[Ready for Use in Masonry]

This ensures optimal mud mortar quality per IS 13077.

IS 13077 - Design Considerations: Key Points

1. Plasticity Index (Clause 4.3)

• Determined as per IS 2720 (Part 5): 1970.
• Recommended range: 12 - 15 for large/important projects.
• For smaller projects, field tests (Clause 7) may suffice.

2. Soil Suitability & Modification (Clause 7.1.3)

• If soil is unsuitable, modify by mixing soils or adding sand/clay.
• Repeat tests to confirm stability.

3. Relevant Indian Standards (Annex A)

4. Compressive Strength (Clause 47.8)

• Expressed in kg/cm² (refer to specific design clauses for values).

Plasticity Index Formula (from IS 2720 Part 5):

[ PI = LL - PL ]

Where:

• PI = Plasticity Index
• LL = Liquid Limit (%)
• PL = Plastic Limit (%)

flowchart TD
    A[Soil Sample] --> B[Determine LL & PL as per IS 2720 (Part 5)]
    B --> C[Calculate PI = LL - PL]
    C --> D{PI Range 12-15?}
    D -- Yes --> E[Soil Suitable for Project]
    D -- No --> F[Modify Soil Composition]
    F --> B

This flow ensures soil meets plasticity criteria for structural stability.

IS 13077: Preparation of Mortar (Mud Mortar)

Key Specifications & Guidelines:

• Soil Preparation (Clause 6.1):

  • Remove gravel, coarse sand (>2 mm), lime, kankar, and vegetable matter.
  • Soil should be clean and fine for uniform mortar.

• Moisture Content (Clause 6.4):

  • Before use, mix prepared soil with water to achieve 35-40% moisture content by weight.
  • Ensures desired consistency and workability.

Important Notes:

• Use plain concrete/RCC bed blocks or cement mortar masonry under concentrated loads for load distribution (Clause 5.3.6).
• Refer to IS 4326:1976 for mud mortar construction in seismic zones.
• Definitions conform to IS 2809:1972.

Formula for Moisture Content:

[ \text{Moisture Content (%)} = \frac{\text{Weight of Water}}{\text{Weight of Dry Soil}} \times 100 = 35% \text{ to } 40% ]

Summary Table: Moisture Content Range for Mud Mortar

flowchart TD
    A[Soil Selection] --> B[Remove gravel, coarse sand (>2mm), lime, kankar, vegetable matter]
    B --> C[Mix soil with water]
    C --> D[Achieve 35-40% moisture content]
    D --> E[Use mortar in masonry]
    E --> F{Load?}
    F -- Concentrated --> G[Provide RCC/Concrete bed blocks or cement mortar masonry]
    F -- Uniform --> H[Direct use]

This ensures proper mud mortar preparation as per IS 13077.

IS 13077: Field Tests for Soil for Masonry Mud Mortar (Annex B, Clause 7.1)

Key Specifications & Procedure:

• Soil Preparation (B-1):
  Grind soil to a fine powder and mix with water in small increments until a plastic mass of workable consistency is formed.

• Ball Formation (B-2):
  Take a handful of prepared soil and form a ball approx. 80 mm diameter.

• Drying & Observation (B-3):
  Dry the ball in the sun and check for:

  • Loss of shape
  • Surface cracks

  These indicate unsuitability of soil for masonry mud mortar.

Moisture Content for Use (Clause 6.4):

• Total moisture content of prepared mortar: 35% to 40% by weight of soil for optimal workability.

Summary Table:

flowchart TD
    A[Soil Ground to Fine Powder] --> B[Add Water Gradually]
    B --> C[Mix to Plastic Mass]
    C --> D[Form 80 mm Ball]
    D --> E[Sun Dry Ball]
    E --> F{Check Ball}
    F -->|No Cracks, Shape Intact| G[Soil Suitable]
    F -->|Cracks or Shape Loss| H[Soil Unsuitable]

This simple field test ensures soil suitability for mud mortar, critical for durable masonry as per IS 13077.

IS 13077: List of Referred Indian Standards (Annex A)

This standard references essential Indian Standards related to soil testing and construction practice, notably:

Key Notes:

• These standards provide soil classification, consistency limits, and earthquake-resistant design guidelines critical for soil suitability and masonry mud mortar.
• Clause 7.1.3 recommends modifying soil composition (mixing soils or adding sand/clay) if initial tests show unsuitability.
• Field tests (Annex B) involve preparing soil balls (~80 mm diameter), drying, and observing cracks or deformation to assess stability.

Summary Diagram: Soil Testing & Modification Flow

flowchart TD
    A[Collect Soil Sample] --> B[Grind & Mix with Water]
    B --> C[Form 80mm Soil Ball]
    C --> D[Dry in Sun]
    D --> E{Check for Cracks or Deformation}
    E -- No --> F[Soil Suitable]
    E -- Yes --> G[Modify Soil Composition]
    G --> B

For detailed procedures, refer to the specific IS codes listed above.

IS 13077: Field Tests for Soil for Masonry Mud Mortar (Annex B, Clause 7.1)

Key Specifications & Procedure:

• Soil Preparation:

  • Grind soil to a fine powder.
  • Add water gradually and knead to a plastic mass with required consistency.

• Test Ball Formation:

  • Form a ball of about 80 mm diameter from the prepared soil mass.

• Drying & Observation:

  • Dry the ball in the sun.
  • Check for loss of shape or surface cracks after drying.

• Moisture Content for Mortar (Clause 6.4):

  • Total moisture content should be 35% to 40% by weight of soil before use.

Summary Table: Field Test for Soil Suitability

Notes:

• Soil failing to retain shape or showing cracks is unsuitable for mud mortar.
• This simple field test ensures quality control before masonry work.

flowchart TD
    A[Soil Sample] --> B[Grind to Fine Powder]
    B --> C[Add Water Gradually]
    C --> D[Knead to Plastic Mass]
    D --> E[Form 80 mm Ball]
    E --> F[Sun Dry Ball]
    F --> G{Check Ball}
    G -->|No Cracks & Shape Retained| H[Soil Suitable]
    G -->|Cracks or Shape Loss| I[Soil Unsuitable]

This concise test helps ensure mud mortar quality per IS 13077 standards.