Limestone (Slab and Tiles)

Scope & Key Specifications from IS 1128 (Limestone Slabs and Tiles)

1. Scope Summary

• Covers limestone slabs and tiles.
• Sizes as per Table 1; intermediate sizes rounded down to next lower size.
• Special sizes can be supplied by mutual agreement.

2. Standard Sizes (Table 1)

3. Sampling & Conformity (Table 3)

• All sampled slabs/tiles checked for dimensions and general requirements.
• Lot accepted if defectives ≤ permissible number.

4. Rounding Off Rules

• Final values rounded per IS 2-1960.
• Number of significant digits retained as per specified values.

This ensures uniformity in size, quality, and acceptance criteria for limestone slabs and tiles under IS 1128.

IS 1128: General Requirements Summary

1. Scope (Clause 1.1)

• Specifies dimensions and physical properties of limestone slabs and tiles for flooring and face work.

2. Sampling & Conformity (Clause 6.3, Table 3)

• Defective Criteria: Any slab/tile failing general requirements or dimensions is defective.
• Lot Acceptance: Number of defectives ≤ permissible number → lot conforms.

3. Rounding Off (Clause 0.3)

• Follow IS 2-1960 for rounding test results.
• Retain the same number of significant digits as specified values.

4. Sizes (Clause 3.1.2)

• Sizes other than Table 1 can be supplied by mutual agreement.

Key takeaway: Sampling and defect limits ensure quality control; strict acceptance criteria maintain dimensional and physical standards.

IS 1128: Dimensions and Tolerances for Limestone Slabs and Tiles

1. Standard Sizes (Clause 3.1.1 & Table 1)

• Sizes between these increments are rounded down to the next lower standard size.
• Custom sizes allowed by mutual agreement (Clause 3.1.2).

2. Tolerances in Thickness (Clause 3.1.3)

3. Rounding Off (Clause 0.3)

• Final test values should be rounded as per IS 2-1960.
• Retain the same number of significant figures as specified.

Summary:

• Length & Breadth: Standard increments; round down if in between.
• Thickness: +5 mm tolerance for ≤25 mm; ±5 mm for >25 mm.
• Custom sizes: Allowed by agreement.
• Rounding: Follow IS 2-1960 for test results.

flowchart LR
    A[Specify Size] --> B{Is size standard?}
    B -- Yes --> C[Use specified size]
    B -- No --> D[Round down to next lower size]
    C & D --> E[Check thickness tolerance]
    E --> F{Thickness ≤ 25 mm?}
    F -- Yes --> G[+5 mm tolerance]
    F -- No --> H[±5 mm tolerance]

This ensures uniformity and quality control in limestone slab production per IS 1128.

IS 1128: Physical Properties of Limestone Slabs and Tiles

Key Specifications & Testing (Clause 6.4, 4.1)

• Sampling: Sub-sample size per lot as per Table 3 (Col 4) for physical testing.
• Tests on sub-sample:
  • Transverse Strength
  • Water Absorption
  • Durability

A lot passes if no sample fails any test.

Physical Properties Requirements (from Table 2, Col 2)

Dimensional Tolerances (Clause 3.2)

• Length & Width: ±1 mm
• Thickness: As per Clause 3.1.3 (typically ±2 mm or specified)

Rounding Off (Clause 0.3)

• Final test values rounded per IS 2-1960 rules.
• Maintain same significant digits as specified values.

Summary Formulae

• Water Absorption (%)
  [ \text{Water Absorption} = \frac{W_{saturated} - W_{dry}}{W_{dry}} \times 100 ]

• Transverse Strength (Modulus of Rupture, MOR):
  [ MOR = \frac{3PL}{2bd^2} ] where
  (P) = Load at failure,
  (L) = Span length,
  (b) = Width,
  (d) = Thickness.

flowchart LR
    A[Lot Sampling] --> B[Select Sub-sample (Table 3)]
    B --> C[Test Transverse Strength]
    C --> D[Test Water Absorption]
    D --> E[Test Durability]
    E --> F{Any Failures?}
    F -->|No| G[Lot Accepted]
    F -->|Yes| H[Lot Rejected]

IS 1128: Marking of Limestone Slabs and Tiles

Key Specifications (Clause 5.1 & 5.1.1)

• Manufacturer's Identification: Each type of limestone slab/tile shall be marked with the manufacturer's identification mark or initials.
• ISI Certification Mark: May also be marked with the ISI Certification Mark if licensed, indicating compliance with IS standards and quality control.

Marking Purpose

• Ensures traceability and quality assurance.
• ISI mark confirms production under ISI supervision and continuous conformity checks.

Relevant Tables Summary

Sampling for Marking Conformity (Clause 6.3)

• All selected slabs/tiles are checked for marking and general requirements.
• Lot passes if defectives ≤ permissible number.

Summary Diagram

flowchart TD
    A[Manufacturer] --> B[Mark slabs/tiles with ID]
    B --> C{ISI License?}
    C -- Yes --> D[Mark with ISI Certification]
    C -- No --> E[Mark only Manufacturer ID]
    D --> F[Quality Assurance & Inspection]
    E --> F

Note: Markings must be clear, durable, and conform to IS 1128 for traceability and quality assurance.

IS 1128: Sampling and Testing Key Points

Sampling (Clause 6.2 & 6.3)

• Sample size depends on lot size as per Table 3 below:

• All sampled slabs/tiles are checked for general requirements and dimensions.
• If defective slabs/tiles ≤ permissible defectives, the lot conforms.

Sampling Method (Clause 6.2.1)

• Use random selection, preferably with a random number table (IS 4905-1968).

Testing & Rounding (Clause 0.3)

• Results should be rounded as per IS 2-1960.
• Keep the same number of significant digits as the specified values.

This ensures a statistically valid and standardized approach to quality control of slabs/tiles under IS 1128.

IS 1128: Criteria for Conformity (Clause 6.3 & Table 3)

Key Points:

• All selected slabs/tiles must be examined for general requirements and dimensions.
• Any slab/tile failing any requirement is considered defective.
• A lot conforms if defective slabs ≤ permissible number.
• Numerical results must be rounded off as per IS 2:1960 with the same decimal places as specified values.
• Stones must be free from soft veins, cracks, flaws, and have uniform texture (Clause 2.1).

Summary Flowchart for Conformity Check:

flowchart TD
    A[Select Sample as per Table 3] --> B[Examine for general requirements & dimensions]
    B --> C{Any defective slabs?}
    C -- No --> D[Lot Conforms]
    C -- Yes --> E{Defective slabs ≤ permissible?}
    E -- Yes --> D
    E -- No --> F[Lot Does Not Conform]

This ensures quality control by statistically sampling slabs/tiles and setting strict defect limits.