Burnt clay flat terracing tiles- Specification, Part 1: Machine made
1993 Edition

Overview of IS 2690 Part 1 Scope

• Scope: Defines quality and testing criteria specific to machine-made burnt clay flat terracing tiles.
• Referenced Standards: Adopts terminologies from IS 2248:1992.
• Rounding Procedure: Test outcomes to be rounded following IS 2:1960, preserving significant figures as mandated.
• Average Test Value Computation: As specified in Clause 4.2.
• Span Definition: Determined by tile dimensions for testing purposes.
• Testing Apparatus: Specifications for support bearers (A & B) and setup for transverse strength tests detailed (refer Fig. 2).

Compliance Highlights

Average Value Formula (Clause 4.2)

[ \text{Average} = \frac{\sum \text{Test Results}}{n} ]

Where n is the count of test samples.

Simplified Test Setup Diagram

graph LR
A[Support Bearer A] -- Span X --> B[Tile Under Test]
B -- Span X --> C[Support Bearer B]

Refer to IS 2690 Part 1:1993 and IS 2248:1992 for detailed equipment and testing procedures.

Key References and Calculation Methods in IS 2690 Part 1 (1993)

1. Average Value Computation (Clause 4.2)

• The average ( \bar{X} ) is calculated by:

  [ \bar{X} = \frac{\sum X_i}{n} ]

  Where ( X_i ) is each individual test result, and ( n ) is the number of tests.

• Final values are rounded off in accordance with IS 2:1960, retaining the required significant figures.

2. Flexural Strength Test Setup (Clause 3.1.2 & Annex B)

• Support span ( X ) equals three-quarters of the tile’s length (longer side for rectangular tiles).
• Load applied at a rate of 45 to 55 kg per minute perpendicular to the span.
• Supports ensure consistent and even load distribution.

3. Testing Equipment Details (Figures 1 & 2)

• Includes:
  • Bearers A & B for supporting tile
  • Load application mechanism with trigger
  • Containers for incremental lead weights
  • Springs and bolts for adjustment

4. Contact Information and Amendments

• BIS contact details provided for standard updates.
• Users must verify amendments issued after the original publication.

Flexural Strength Test Setup Summary

flowchart LR
    A[Tile Sample] --> B[Bearers (Span = 3/4 length)]
    B --> C[Load Applied Perpendicularly]
    C --> D[Load Added via Lead Shots]
    D --> E[Measure Deflection and Failure Load]
    E --> F[Compute Average Strength]

This guide corresponds to IS 2690 Part 1 flexural strength testing methodology.

Definitions and Terminology per IS 2690 Part 1 (1993)

• Reference for Terms: All definitions follow IS 2248:1992, Clause 3.0, related to structural clay products.

• Rounding Protocol: Test and analysis results must be rounded off as per IS 2:1960, keeping consistent significant figures.

• Average Value Computation: Arithmetic mean as per Clause 4.2 and Table B-4.

• Span for Testing: Defined according to tile dimension (see Fig. 2 in IS 2690 Part 1).

Summary Table of Definitions and Calculations

Average Calculation Formula

[ \text{Average} = \frac{\sum_{i=1}^n X_i}{n} ]

Where:

• (X_i) = individual test result
• (n) = total number of samples

For detailed terminologies, consult IS 2248:1992.

General Quality Norms in IS 2690 Part 1

• Rounding Test Results (Clause 4):
  Test values must be rounded following IS 2:1960, maintaining the same significant digits as the standard.

• Average Value Calculation (Clause 4.2):
  The mean value is calculated by:

  [ \bar{X} = \frac{1}{n} \sum_{i=1}^n X_i ]

• Terminology Reference (Clause 3.0):
  Use definitions from IS 2248:1992.

• Testing Apparatus (Fig. 2):
  Specifies bearer supports and span based on tile dimensions for flexural testing.

• Water Absorption Method (Annex A, Clause 6.1):
  Describes specimen preparation and testing procedure.

Quality Test Reporting Summary

flowchart LR
    A[Test Tile] --> B[Perform Tests]
    B --> C[Record Measurements]
    C --> D[Calculate Average \(\bar{X}\)]
    D --> E[Round Values per IS 2:1960]
    E --> F[Verify Compliance]
    F --> G{Meets Criteria?}
    G -->|Yes| H[Accept Tile]
    G -->|No| I[Reject or Re-test]

This ensures uniform assessment of tile quality.

Specifications for Terracing Tiles Dimensions and Shape (IS 2690 Part 1)

Dimensions and Form

• Tiles must have consistent shape and dimensions.
• Surfaces: may be plain or grooved.
• Reverse side must be corrugated to aid mortar adhesion.

Permissible Deviations (Clause 5.1.4)

Warpage Limits (Clause 5.2.1)

• Maximum allowable warpage is not more than 1% of tile dimension.
• Measurement technique:
  • Place a straightedge on the tile over a flat surface.
  • Use a metal wedge to measure the maximum gap.

Summary Table

flowchart LR
    A[Terracing Tile] --> B[Uniform Shape and Size]
    A --> C[Face: Plain or Grooved]
    A --> D[Back: Corrugated]
    A --> E[Dimensional Tolerances]
    E --> F[Pressed: ±2%]
    E --> G[Extruded: ±3%]
    A --> H[Warpage ≤ 1%]
    H --> I[Measured with Straightedge and Wedge]

This ensures consistent tile quality for installation and durability.

Water Absorption Requirements in IS 2690 Part 1

Calculation Formula (Clause 3.1)

[ \text{Water Absorption 5} = \frac{B - A}{A} \times 100 ] Where:

• A = Dry weight of tile specimen (grams)
• B = Weight after 24-hour immersion in cold water (grams)

Reporting (Clause 3.2)

• The final water absorption value is the average of multiple tile specimens.

Specimen Preparation (Annex A, Clause 6.1)

• Tiles are dried and weighed accurately before immersion.
• Immersion duration is exactly 24 hours in cold water.

Warpage Limit (Clause 5.2.1)

• Maximum warpage allowed is ≤ 1% of tile dimension.
• Measurement with straightedge and metallic wedge.

Summary Table

flowchart TD
    A[Dry Tile Weight (A)] --> B[Immerse in Water for 24 Hours]
    B --> C[Wet Tile Weight (B)]
    C --> D[Compute Water Absorption Percentage]
    D --> E[Report Average Water Absorption]

This test helps ensure tiles have adequate durability and low porosity.

Flexural Strength Evaluation as per IS 2690 Part 1

Calculation Formula (Clause 4.1 & B-4.1)

[ \text{Flexural Strength} = \frac{150 \times W \times S}{b \times t^2} \quad \text{kg/cm}^2 ]

Where:

• W = Load at failure (kg)
• S = Span length (mm), equal to 3/4 of tile length
• b = Tile width (mm)
• t = Tile thickness (mm)

Testing Setup (Clause 3.1.2 & Annex B)

• Tile placed flat on supports spaced at 3/4 tile length
• Supports along the longer edge for rectangular tiles
• Load applied perpendicularly at a rate of 45–55 kg/min
• Load distribution is made uniform using packing between tile and bearers

Additional Requirements

• Average water absorption for tested tiles should be ≤ 15% (Clause 6.1)
• Test sample size: 6 tiles (Annex B-1)
• Tile testing machine details per Fig. 1 in IS 2690 Part 1

Flexural Strength Parameter Summary

flowchart LR
    A[Tile Sample] --> B[Supported on Bearers (Span = 3/4 length)]
    B --> C[Load Applied Perpendicular to Span]
    C --> D[Measure Breaking Load (W)]
    D --> E[Compute Flexural Strength]

This method standardizes flexural strength determination for roofing tiles.

Sampling and Testing Protocols in IS 2690 Part 1

Sampling Guidelines (Clause 8.1)

• Select a minimum of 6 tiles per 1000 tiles (or fraction) from the batch.
• Lot testing requires at least 15 tiles.
• Additional samples can be taken at the purchaser’s discretion.

Testing and Result Recording (Clause 4.2 & Table B-4)

• Calculate the average of test outcomes.
• Apply rounding rules per IS 2:1960.
• Retain significant figures consistent with specification.

Strength Specification (Clause 7.1)

• Average Modulus of Rupture of 6 tiles should be ≥ 2 N/mm².

Sampling Formula

[ \text{Sample Size} = \max(15, 6 \times \lceil \frac{\text{Lot Size}}{1000} \rceil) ]

Testing Setup (Figure 2)

• Tile supported by two bearers
• Load applied at center span equal to tile dimension
• Transverse bending test to find modulus of rupture

Sampling and Testing Summary

flowchart LR
    A[Tile Lot] --> B{Tiles > 1000?}
    B -- Yes --> C[Samples = 6 x number_of_1000s]
    B -- No --> D[Samples = 6]
    C --> E{Samples < 15?}
    D --> E
    E -- Yes --> F[Samples = 15]
    E -- No --> G[Use calculated samples]
    F --> H[Conduct Testing]
    G --> H
    H --> I[Calculate Average MOR]
    I --> J{MOR ≥ 2 N/mm²?}
    J -- Yes --> K[Accept Batch]
    J -- No --> L[Retest or Reject]

This ensures reliable lot quality assessment.

Marking Requirements for Terracing Tiles (IS 2690 Part 1, 1993)

Marking Specifications (Clause 9.1 & 9.1.1):

• Each tile must be clearly and permanently marked with:
  • The manufacturer’s identification
  • The letter 'M' indicating it is machine manufactured
• The marking area should not exceed 5% of the tile’s surface area.
• Tiles may carry the BIS Standard Mark if licensed.

Important Marking Details:

• The Standard Mark confirms compliance with IS 2690 under BIS supervision.
• Markings must be durable and visible without compromising tile integrity.
• Test results related to marking must be rounded per IS 2:1960.

Marking Summary Table

Marking Process Flow

flowchart LR
    A[Tile Surface] --> B{Marking Area ≤ 5%?}
    B -- Yes --> C[Apply Manufacturer ID + 'M']
    B -- No --> D[Reduce Marking Size]
    C --> E[Add Standard Mark (Optional)]

This ensures traceability and quality assurance of tiles.

Water Absorption Test Protocol (IS 2690 Part 1)

Test Steps (Clause A-2.1)

• Dry tile samples in an oven at 100 to 110°C until weight stabilizes.
• Cool samples and record dry weight (A).
• Fully immerse samples in clean water at 24 to 30°C for 24 hours.
• Remove, wipe surface moisture carefully, and weigh wet specimen (B) within 3 minutes.

Calculation (Clause A-3.1)

[ \text{Water Absorption 5} = \frac{B - A}{A} \times 100 ]

Where:

• A = Dry weight (grams)
• B = Weight after immersion (grams)

Reporting (Clause A-3.2)

• Average water absorption from multiple specimens is reported.

Summary Table

This test confirms tile performance related to moisture resistance and durability.

Flexural Strength Measurement Method (IS 2690 Part 1)

Calculation Formula (Clause B-4.1):

[ \text{Flexural Strength} = \frac{150 \times W \times S}{b \times t^2} \quad \text{kg/cm}^2 ]

Where:

• W = Breaking load (kg)
• S = Span length (mm), 3/4 of tile length
• b = Tile width (mm)
• t = Tile thickness (mm)

Testing Setup (Clause B-3.1.2):

• Tile supported flatwise on two bearers.
• Span set at 3/4 of tile length.
• Load applied perpendicular to span at 45–55 kg/min.
• Packing material used to ensure uniform load application.

Additional Details:

• Average water absorption for tested samples ≤ 15% (Clause 6.1).
• Use tile testing apparatus as per Fig. 1 with specified metal components.

Summary Table for Flexural Strength

flowchart LR
    A[Tile Sample] --> B[Supported on Bearers (Span = 3/4 length)]
    B --> C[Load Applied at 45-55 kg/min]
    C --> D[Measure Breaking Load (W)]
    D --> E[Calculate Flexural Strength]

This procedure ensures accurate flexural strength evaluation as per the standard.