Asbestos Cement Products - Methods of Test

IS 5913: Scope - Key Specifications & Formulas

Scope Summary: IS 5913 specifies test methods and requirements for asbestos cement pipes and sheets, including bursting strength and bending tests.

1. Bursting Strength Formula

The unit bursting strength ( R ) (in N/mm²) is calculated by:

[ R = \frac{p \times d}{2 \times e} ]

Where:

• ( p ) = internal pressure at rupture (MPa)
• ( d ) = actual internal diameter (mm) (average of two perpendicular measurements at both ends)
• ( e ) = actual wall thickness (mm) (average of three measurements along fracture line)

2. Minimum Length of Bursting Test Piece

3. Rounding Off

• Follow IS 2:1960 for rounding final values.
• Retain the same number of significant digits as specified in the standard.

4. Referenced Standards

flowchart LR
    A[Test Piece] --> B[Measure Diameter (d)]
    A --> C[Measure Thickness (e)]
    D[Apply Internal Pressure (p)] --> E[Pressure at Rupture]
    B & C & E --> F[Calculate Bursting Strength R = (p × d) / (2 × e)]

This concise summary covers the scope essentials

IS 5913 Key References, Formulas, and Specifications

1. References (Table 2)

2. Bursting Strength Formula (Clause 10.2)

[ R = \frac{p \times d}{2e} ]

• R = Unit bursting strength (N/mm²)
• p = Internal pressure at rupture (MPa)
• d = Actual internal diameter (mm), average of two perpendicular measurements
• e = Wall thickness at fracture (mm), average of three measurements

3. Minimum Length of Bursting Test Piece (mm)

4. Longitudinal Bending Stress (Clause 7.2.3)

[ R = \frac{3 p l}{2 b e^2} ]

• R = Unit bending stress (MN/m²)
• p = Breaking load (N)
• l = Clear span between supports (mm)
• b = Width of test piece (mm)
• e = Thickness of test piece (mm)

Notes:

• Rounding off numerical results per IS 2:1960.
• For building boards, average bending strength from longitudinal and transverse tests is used.
• Alternative tensile strength tests may be agreed upon.

This concise summary aids quick reference for testing and reporting per IS 5913.

IS 5913: Sampling of Test Specimens – Key Points

• Specimen Size & Shape:

  Clause	Material	Specimen Dimensions (mm)	Notes
  6.1	Sheets	65 × 65 (approx. 10,000 mm² surface)	Includes edges; 3 specimens per sheet
  6.1	Pipes	65 (length) × 65 (curved center)	Approx. 10,000 mm² surface; 3 specimens
  4.1	Sheets/Boards	175 × 75	1 specimen per selection
  4.1	Pipes	25 mm length	1 specimen per selection
  1.25	Sheets	Full sheet or 1.25 m length cut	Selected per relevant sampling method
  7.2.2	Sheets	250 × 250	2 specimens per sheet; test longitudinal & transverse

• Sampling Notes:

  • Specimens must be cut from the same part of the sheet (e.g., 200 mm from edge).
  • Fibre direction must be marked; if unclear, test in two perpendicular directions.
  • Surface area includes edges for accurate representation.

Specimen Surface Area Calculation Example (Clause 6.1):

[ \text{Surface Area} \approx 10,000 \text{ mm}^2 ]

For a square specimen:

[ \text{Side} = \sqrt{10,000} = 100 \text{ mm (approx.)} ]

But IS 5913 recommends 65 mm × 65 mm with edges included, considering curved surfaces for pipes.

flowchart LR
    A[Select Sheet or Pipe] --> B[Cut Specimens as per Clause]
    B --> C{Material Type}
    C -->|Sheet| D[Cut 3 specimens 65x65 mm or 2 specimens 250x250 mm]
    C -->|Pipe| E[Cut 3 specimens 65x65 mm (curved)]
    D --> F[Mark Fibre Direction]
    F --> G[Test Longitudinal & Trans

Preparation and Conditioning of Specimens (IS 5913 Key Points)

• Water Immersion (Clause 7.2.2.1 & 4.2.1):

  • Immerse specimens completely in water at 15–35℃ for 18 to 24 hours.
  • In colder regions, water temp may be as low as 5℃, but not less.
  • After immersion, remove excess moisture with a damp cloth before weighing.
  • Specimens placed on mild steel bearers (40 mm dia), parallel and in the same horizontal plane (Fig. 4).

• Acetic Acid Conditioning (Clause 6.2.1):

  • Immerse specimens in 270 ml of 5% acetic acid at 15–35℃ for 24 hours.
  • Use separate vessels for each specimen.
  • Concentration checked by titration with ~0.5 N NaOH using thymol blue indicator.
  • For coated specimens, remove or protect coatings (e.g., paraffin wax for one side).

• Specimen Placement:

  • Specimens placed centrally on self-aligning bearers, underside in contact with two bearers.

Summary Table: Conditioning Parameters

flowchart LR
    A[Specimen] --> B[Immersion in Water (15-35℃, 18-24h)]
    B --> C{Test Type?}
    C -->|Permeability| D[Placed on 3 steel bearers (40mm dia)]
    C -->|Acetic Acid Test| E[Immersion in 5% Acetic Acid (24h)]
    E --> F[Titration of acid concentration]

This ensures standardized specimen conditioning for reliable test results per IS 5913.

IS 5913: Test for Impermeability of Sheets

Key Clauses & Procedure

• Clause 5.1: Test for impermeability is done by methods in Clauses 5.2 and 5.3 (not detailed here).
• Clause 6.2.1:
  • Immerse each specimen (or pair) upright in 270 ml of 5% acetic acid at 15–35°C for 24 hours.
  • Use separate vessels and fresh solution for each specimen.
  • Determine acid concentration before and after immersion by titration against ~0.5 N sodium hydroxide using thymol blue indicator.
  • For titration:
    • Stir 10 ml acid solution, dilute to 100 ml, add 10 drops thymol blue (0.040 g/100 ml alcohol).
• Note:
  • Coatings must be removed or protected (e.g., paraffin wax for one-sided coated sheets).
  • Exposed surface area should be ~10,000 mm² per specimen pair.

Corrugation Categories (Fig. 1)

Summary Diagram of Test Setup

flowchart LR
    A[Specimen (Coating removed/protected)] --> B[Placed upright in vessel]
    B --> C[270 ml 5% Acetic Acid @ 15-35°C]
    C --> D[Immersion for 24 hours]
    D --> E[Titration with NaOH (0.5 N) using thymol blue]
    E --> F[Measure acid concentration before & after]

Important: This test applies to asbestos cement sheets, not surface coatings. Use fresh solutions and avoid specimen contact during testing (Clause 4.3.1).

IS 5913: Acid Resistance Test Key Points

Procedure (Clause 6.2.1)

• Immerse each specimen upright for 24 hours in 270 ml of 5% acetic acid at 15–35°C.
• Use separate vessels and fresh solution for each specimen.
• Measure acetic acid concentration before and after immersion by titration with 0.5 N NaOH using thymol blue indicator.
• For titration: take 10 ml acid solution, dilute to 100 ml, add 10 drops thymol blue.

Reporting Result (Clause 6.3)

Calculate acetic acid consumed per unit area by:

[ \text{Mass of acetic acid (g/m}^2) = \frac{0.030 \times 270 \times (x - y)}{10 \times A} ]

Where:

• (x) = ml of 0.5 N NaOH used initially
• (y) = ml of 0.5 N NaOH used after immersion
• (A) = area of specimen in m²

Notes

• Coatings must be removed or protected (paraffin wax) before testing.
• Test applies to asbestos cement materials only.
• Area exposed ≈ 10,000 mm² (0.01 m²).

Summary Table: Corrugation Category vs. Number of Corrugations (for permeability test)

This formula and procedure ensure standardized quantification of acid resistance by measuring acid consumption per unit area.

IS 5913 - Load Bearing Capacity Test for Flat Sheets and Building Boards

Key Formula (Clause 7.2.3)

Unit bending stress, ( R ) (in MN/m²), is calculated separately for longitudinal and transverse directions as:

[ R = \frac{3 p l}{2 b e^2} ]

Where:

• ( p ) = Breaking load (N)
• ( l ) = Clear span between supports (mm)
• ( b ) = Width of test specimen (mm)
• ( e ) = Thickness of test specimen at breaking section (mm)

Test Specimen Dimensions (Fig. 3)

• Size: 250 mm × 250 mm (square specimen)

Reporting (Clause 7.2.3)

• Record breaking load separately for longitudinal and transverse directions.
• Calculate ( R ) for both directions.
• Take the arithmetic mean of the two ( R ) values as the final unit bending stress for the specimen.

Summary Table

flowchart TD
    A[Specimen: 250x250 mm] --> B[Apply Load p at center]
    B --> C[Measure Breaking Load p]
    C --> D[Calculate R = (3pl)/(2be²) Longitudinal]
    C --> E[Calculate R = (3pl)/(2be²) Transverse]
    D --> F[Average R values]
    E --> F
    F --> G[Report final bending stress]

This test ensures the sheet/board's bending strength is evaluated accurately in both principal directions per IS 5913.

IS 5913 - Transverse Crushing Test for Pipes: Key Formulas & Specifications

1. Unit Transverse Crushing Strength, R (N/mm²)

[ R = \frac{n \times P_e \times (d + e)}{2 \times W} ]

Where:

• ( P_e ) = Breaking load (N)
• ( d ) = Internal diameter (mm), average of two perpendicular measurements
• ( e ) = Wall thickness (mm), average of three measurements at fracture
• ( n ) = Factor based on diameter:
  • 0.26 for ( d \leq 100 ) mm
  • 0.30 for ( d > 100 ) mm
• ( W ) = Section modulus of pipe wall

2. Section Modulus, W

[ W = \frac{\pi}{32} \times \frac{(d + 2e)^4 - d^4}{d + 2e} ]

3. Additional Notes

• Load is applied evenly over the test length (see Fig. 5 in IS 5913).
• Diameter and thickness must be measured accurately at the fracture section.
• The factor ( n ) accounts for pipe curvature effects.

Summary Table

flowchart TD
    A[Apply Load Evenly] --> B[Pipe Specimen]
    B --> C[Measure d & e at fracture]
    C --> D[Calculate W]
    D --> E[Calculate R using formula]
    E --> F[Report Transverse Crushing Strength]

This concise summary provides the essential formulas and parameters for conducting and reporting the transverse crushing test on pipes as per IS 5913.

IS 5913: Hydraulic Pressure Test for Pipes — Key Points

Test Procedure (Clause 5.2.2)

• Pipes placed on hydraulic press; ends sealed to avoid axial compression.
• Pressure gauge accuracy: ±0.05 N/mm².
• For building pipes, pressure raised to 0.1 N/mm².
• For other pipes, pressure raised to class-specific value.
• Maintain pressure for 30 seconds to check leakage, fissure, sweating.
• For pipes ≤ 350 mm diameter, test duration can be reduced to 5 seconds if pressure is increased by 10%.

Pressure Application (Clause 3.4.3.3)

• Pressure applied steadily to cause rupture between 15 to 30 seconds.
• Test piece ends may be machined to nominal wall thickness.
• Avoid axial compression during pressure application.

Reporting Formula (Clause 8.3)

Unit transverse crushing strength, R (N/mm²):

[ R = \frac{M}{W} ]

Where:

• ( M = nP \times \frac{(d+e)}{2} ) — Maximum ring bending moment
• ( n = 0.26 ) (diameter ≤ 100 mm), ( n = 0.30 ) (diameter > 100 mm)
• ( P_e ) = Breaking load (N)
• ( d ) = Internal diameter (mm), average of two perpendicular measurements
• ( e ) = Wall thickness (mm), average of three measurements at fracture
• ( W = \frac{l e^2}{6} ) — Modulus of resistance of pipe wall
• ( l ) = Length of test piece (mm)

Summary Table for Hydraulic Pressure Test

flowchart TD
   

IS 5913: Hydraulic Bursting Test for Pipes - Key Points

Test Procedure (Clause 10 & 3.4.3.3)

• Pipe specimen is subjected to internal hydraulic pressure in a device preventing axial compression.
• Pressure is applied at a constant rate, ensuring rupture occurs between 15 to 30 seconds.
• Specimens can be non-immersed or immersed in water for 48 hours (per IS 1592).
• Test piece ends may be machined to nominal wall thickness including tolerances.

Important Formulas (Clause 8.3)

Unit transverse crushing strength, ( R ) (N/mm²):

[ R = \frac{M}{W} ]

Where:

• ( M = nP \frac{(d+e)}{2} ) = Maximum ring bending moment (N·mm)
• ( n = \begin{cases} 0.26 & \text{for } d \leq 100,mm \ 0.30 & \text{for } d > 100,mm \end{cases} )
• ( P_e ) = Breaking load (N)
• ( d ) = Actual internal diameter (mm), average of two perpendicular measurements
• ( e ) = Actual wall thickness (mm), average of three measurements at fracture
• ( W = \frac{l e^2}{6} ) = Modulus of resistance of pipe wall
• ( l ) = Length of test piece (mm)

Reporting (Clause 9.3)

• Report any fissure, leakage, or sweating on pipe surface during test.

Summary Table: Parameters for Bursting Test

flowchart TD

IS 5913: Longitudinal Bending Test for Pipes — Key Formulas & Specs

1. Unit Longitudinal Bending Strength, R (N/mm²)

[ R = \frac{P \times L}{W} ]

Where:

• (P) = Breaking load (N)
• (L) = Distance between supports (mm)
• (W) = Section modulus of pipe cross-section (mm³)

2. Section Modulus, (W)

[ W = \frac{\pi}{32} \times \frac{(d + 2e)^4 - d^4}{d + 2e} ]

Where:

• (d) = Internal diameter (mm), average of two perpendicular measurements at fracture
• (e) = Wall thickness (mm), average of three measurements along fracture line

3. Measurement Notes

• (d) and (e) must be measured at the broken cross-section after the test.
• (L) is the clear span between the supports during the test.

4. Summary Table

5. Test Setup (Fig. 6 Reference)

• Pipe supported at two points, load applied at center.
• Load applied until fracture.

graph LR
A[Support] -- L --> B[Pipe Specimen] -- Load P applied at center --> C[Support]

This formula and procedure ensure accurate evaluation of pipe bending strength per IS 5913 Clause 11.4.

IS 5913: Straightness Test for Pipes

Key Specifications (Clause 12)

• Test Methods: Manufacturer chooses one of two methods:

  1. Rolling Test (12.2.1):

     • Pipe is rolled on two parallel runners spaced at 2/3 of the pipe's nominal length.
     • Measure the deviation (f) at mid-span on the external surface.
     • Illustrated in Fig. 7(a).

  2. Floor Test (12.2.2):

     • Pipe laid on the floor.
     • Measure the deviation (j) from floor to outer surface at pipe ends.
     • Illustrated in Fig. 7(b).

Formula (Clause 2.547)

[ R = 2.547 \times P \times \frac{(d + 2e)(d + 2e)^*}{12} - d' ]

• Where:
  • (R), (P), (d), (e), (d') are pipe parameters (units consistent).

Summary Table

flowchart LR
    A[Pipe] --> B[Roll on two runners]
    B --> C[Distance = 2/3 pipe length]
    C --> D[Measure deviation f at mid-span]
    A --> E[Lay pipe on floor]
    E --> F[Measure deviation j at ends]

Note: Use whichever method suits manufacturing convenience; deviations help assess pipe straightness compliance.

IS 5913: Determination of Density for Flat Sheets

Key Specifications & Procedure (Clause 13)

• Dry Mass (M):
  Dry the test specimen to constant mass at 100 to 105 ℃ in an oven, then measure mass in grams (g).

• Volume (V):
  Determine volume by:

  • Immersing saturated specimen in water and measuring displaced water volume, or
  • Any other precise volume measurement method, in cm³.

Density Calculation (Clause 13.3)

[ \boxed{ p = \frac{M}{V} } ]

Where:

• ( p ) = density (g/cm³)
• ( M ) = dry mass (g)
• ( V ) = volume (cm³)

Notes:

• Ensure specimen is fully dried before mass measurement.
• Volume measurement should be accurate to minimize errors.
• Density helps evaluate material quality and uniformity.

flowchart TD
    A[Test Specimen] --> B[Dry at 100-105 ℃]
    B --> C[Measure Dry Mass (M)]
    A --> D[Immerse in Water]
    D --> E[Measure Displaced Volume (V)]
    C & E --> F[Calculate Density p = M/V]

This concise method aligns with IS 5913 for reliable density determination.

IS 5913: Frost Cracking Test for Sheets - Key Points

Test Procedure (Clause 14.2)

• Specimen preparation: Immerse sheets in water for 48 hours.
• Freeze-thaw cycles: Subject specimens to 25 cycles between -20°C and +20°C (±3°C tolerance).
• Cycle duration: To be agreed based on intended use.

Density Calculation (Clause 13.3)

[ p = \frac{M}{V} ]

• (p) = Density (g/cm³)
• (M) = Dry mass of specimen (g)
• (V) = Volume of specimen (cm³)

Support & Loading (Clause 7.1.2)

• Specimens immersed in water at 15–35°C for 24 hours before testing.
• Supported on parallel rigid bearers (50 mm wide, spaced 1 m apart).
• Load applied at mid-span with a 230 ± 5 mm wide flat beam.
• Felt or soft fiber (10 mm thick) placed between supports and specimen.
• Load applied at a uniform rate ≤ 2000 N/min.

Summary Diagram: Frost Cracking Test Setup

graph LR
A[Specimen immersed in water 48h] --> B[25 freeze-thaw cycles (-20°C to +20°C)]
B --> C[Support on rigid bearers (50 mm wide, 1 m apart)]
C --> D[Load applied mid-span with flat beam (230 mm wide)]
D --> E[Observe for frost cracking]

This test evaluates sheet durability under freeze-thaw stresses, critical for cold climate applications.

IS 5913 - Determination of Colour and Staining Power of Pigments

Key Specifications (Clause 15.4.1)

• Pigments (except Carbon Black): Mix pigment with Ordinary Portland Cement (IS 269) for testing.

Testing Method (Clause 15.1)

• Pigments are tested when incorporated in asbestos for coloring.
• Pigments must conform to relevant IS standards.

Acceptance Criteria (Clause 14.3)

• Test pieces should show no cracking or surface alteration after testing to be satisfactory.

Summary

• Use 2g pigment + 20g cement for colour comparison.
• Use 0.2g pigment + 20g cement for staining power.
• Observe physical integrity post-test for acceptance.

flowchart LR
    A[Pigment Sample] --> B{Type of Test}
    B -->|Colour Comparison| C[Mix 2g pigment + 20g cement]
    B -->|Staining Power| D[Mix 0.2g pigment + 20g cement]
    C --> E[Test Sample Preparation]
    D --> E
    E --> F[Testing]
    F --> G{Result}
    G -->|No Cracking/Alteration| H[Satisfactory]
    G -->|Cracking/Alteration| I[Unsatisfactory]

This ensures standardized evaluation of pigment colour and staining power per IS 5913.