Requirements for compression testing machine used for testing of concrete and mortar

IS 14858 - Scope & Key Specifications

• Scope: IS 14858 covers test methods and specifications related to bearing blocks used in structural applications, ensuring standardized testing and dimensional control.

• Rounding Off Values:
  Final test values must be rounded as per IS 2:1960, retaining the same number of significant figures as specified.

• Bottom Bearing Blocks (Clause 6.2.4.1):
  The maximum diameter of the bearing face for suspended spherically seated blocks depends on the test specimen diameter:

• Note: Square bearing faces are allowed if the largest inscribed circle diameter does not exceed the specified max diameter.

This ensures uniformity in bearing block dimensions for reliable load transfer and testing consistency.

IS 14858 Key References and Specifications

• Referenced Standards:
  The provisions of IS 14858 incorporate other standards by reference. Users must check the latest editions of these standards for compliance.

• Rounding Off (IS 2:1960):
  Final test or analysis results must be rounded off per IS 2:1960 rules, retaining the same number of significant digits as the specified values.

• Surface Texture (Clause 7.6):

  • R-value of auxiliary platen contact faces: 0.4μm ≤ R ≤ 3.2μm

• Bearing Face Diameter Limits (Clause 6.2.4.1):
  Maximum bearing face diameter for suspended spherically seated blocks depends on test specimen diameter:

• Note: Square bearing faces allowed if inscribed circle diameter ≤ max diameter.

flowchart LR
    A[Test Specimen Diameter] --> B[Max Bearing Face Diameter]
    B --> C{Shape of Bearing Face}
    C -->|Circular| D[Diameter ≤ Max]
    C -->|Square| E[Inscribed Circle Diameter ≤ Max]

This ensures proper bearing contact and load distribution as per IS 14858.

IS 14858: Definitions – Key Points

IS 14858 primarily references other standards and general rules rather than providing explicit formulas or tables under "Definitions." Here are the essentials:

• Rounding Off: Follow IS 2:1960 for rounding test or calculation results.

  • Round to the same number of significant digits as the specified value.

• Referenced Standards: This code aligns with international practices, notably ASTM C39-86 for compressive strength testing of concrete cylinders.

Key Notes:

• No direct formulas or tables are given in the Definitions section.
• Definitions are consistent with international standards for clarity and uniformity.
• For specific test methods or calculations (e.g., compressive strength), refer to ASTM C39 or related IS codes.

IS 2:1960 Rounding Rule Summary:

If you need formulas or tables for compressive strength or other parameters, please specify, and I can provide those per IS 14858 or related standards.

IS 14858: General Requirements - Key Points

• Rounding Off (IS 2:1960): Final test or calculated values must be rounded off following IS 2 rules, retaining the same significant figures as specified.

• Bearing Blocks (Clause 6.2.4.1):
  The maximum diameter of the bearing face for suspended spherically seated blocks depends on the test specimen diameter:

• Note: Square bearing faces are allowed if the largest inscribed circle diameter does not exceed the max diameter above.

• Referenced Standards:

  • IS 516:1959 for concrete strength testing methods.
  • Always check for the latest edition of referenced standards.

flowchart TD
    A[Test Specimen Diameter] --> B[Determine Max Bearing Face Diameter]
    B --> C{Shape of Bearing Face}
    C -->|Circular| D[Diameter ≤ Max Diameter from Table]
    C -->|Square| E[Inscribed Circle Diameter ≤ Max Diameter]

This ensures conformity in bearing block sizing and test result precision per IS 14858.

IS 14858: Load Pacers and Load Scale Indicators Key Points

Load Pacers (Clause 5.2 & 5.2.2)

• Scale Linearity:
  The scale on the pacer must be basically linear.
• Scale Representation:
  1 mm on the scale ≤ 100 N/s.
• Accuracy:
  ±5% over the operating range.

Load Scale Indicators (Clause 5.3 & 5.3.1)

• Visual Display Requirements:
  • Easily readable dials, scales, or electrical load indicators.
  • Visual display may be supplemented by calibrated recording devices.
• Maximum Load Register:
  • Must have a resettable device to register the specimen's maximum load.
• Needle Width:
  • Needle width < width of graduation marks to ensure clarity.

Summary Table

flowchart LR
    A[Load Pacer] --> B[Linear Scale (1mm ≤ 100N/s)]
    B --> C[Accuracy ±5%]
    A --> D[Load Scale Indicator]
    D --> E[Visual Display (Dial/Scale/Electrical)]
    D --> F[Resettable Max Load Register]
    E --> G[Needle Width < Graduation Width]

This ensures precise, clear, and reliable load measurement during testing per IS 14858.

IS 14858 Key Points: Machine Platens & Bearing Blocks

1. Bearing Blocks (Clause 6.2.4.4)

• Movable portion must fit closely in the spherical seat.
• Rotation & tilt: Bearing face must rotate freely and tilt ≥ 4° in any direction.
• Ensures uniform load distribution and prevents stress concentration.

2. Auxiliary Platens (Clause 7.6)

• Surface texture R-value (roughness) of contact faces:
  0.4 µm ≤ R ≤ 3.2 µm
• Ensures proper friction and load transfer.

3. Spacing Blocks (Clauses 6.2.2 & 8.2)

• Bottom bearing block surface:
  • Top & bottom surfaces parallel.
  • Horizontal dimension ≥ specimen dimension + 3%.
• Material hardness ≥ 550 HV (per IS 1501).
• Material must resist irreversible deformation under load.

Summary Table

flowchart LR
    A[Machine Platen] --> B[Bearing Block]
    B --> C[Spherical Seat]
    C --> D[Free rotation & tilt ≥ 4°]
    A --> E[Auxiliary Platen]
    E --> F[Surface roughness R=0.4-3.2 µm]
    A --> G[Spacing Block]
    G --> H[Hardness ≥ 550 HV]
    G --> I[Dimension ≥ specimen + 3%]
    G --> J[Parallel top & bottom surfaces]

This ensures reliable load transfer, durability, and accurate testing conditions per IS 14858.

IS 14858: Auxiliary Platens and Spacing Blocks - Key Points

1. Auxiliary Platens

• Surface Texture (Clause 7.6):
  • R value (surface roughness) of contact faces: 0.4 µm ≤ R ≤ 3.2 µm
• Function: Used to adjust the platen spacing and provide a uniform bearing surface.

2. Spacing Blocks

• Number (Clause 8.1):
  • Maximum 4 spacing blocks allowed, placed beneath or on the lower platen to reduce spacing.
• Flatness & Parallelism (Clause 8.3):
  • Must meet the same flatness and parallelism tolerances as auxiliary platens.
• Material & Design:
  • Should ensure uniform load distribution without introducing stress concentrations.

3. Spherical Bearing Blocks (Clause 6.2.4.4)

• The movable bearing face must:
  • Be held closely in the spherical seat.
  • Rotate freely and tilt at least 4° in any direction.

Summary Table: Auxiliary Platen & Spacing Block Requirements

flowchart LR
    A[Machine Platen] --> B[Auxiliary Platen]
    B --> C[Spacing Blocks (max 4)]
    C --> D[Spherical Bearing Block]
    D --> E[Movable Bearing Face: rotates & tilts ≥ 4°]

Note: Ensure all surfaces are machined and inspected per IS 14858 tolerances to maintain test accuracy and machine safety.

IS 14858: Spacing Blocks Specifications Summary

Material & Hardness (Clause 8.2)

• Spacing blocks on the lower machine platen must have:
  • Hardness ≥ 550 (tested per IS 1501)
  • No irreversible deformation under machine use

Flatness & Parallelism (Clause 8.3)

• Must comply with tolerances for auxiliary platens (strict flatness and parallelism)

Surface Texture (Clause 7.6)

• Surface roughness R value of contact faces:
  [ 0.4 \mu m \leq R \leq 3.2 \mu m ]

Bearing Face Diameter Limits (Clause 6.2.4.1)

• Note: Square bearing faces allowed if largest inscribed circle diameter ≤ max diameter above.

Quick Checklist for Spacing Blocks:

• Hardness ≥ 550 (IS 1501)
• No irreversible deformation
• Flatness & parallelism per auxiliary platen specs
• Surface roughness 0.4µm to 3.2µm
• Bearing face diameter per Table 6.2.4.1 limits

flowchart TD
    A[Spacing Blocks] --> B[Material: Hardness ≥ 550]
    A --> C[Flatness & Parallelism per Aux. Platen]
    A --> D[Surface Roughness R: 0.4µm to 3.2µm]
    A --> E[Bearing Face Diameter Limits]
    E --> F{Diameter of Test Specimen}
    F -->|51 mm| G[Max 105 mm]
    F -->|76 mm| H[Max 127 mm]
    F -->|102 mm| I[Max 165 mm]
    F -->|152 mm| J[Max 254 mm]
    F -->|203 mm| K[Max 279 mm]

This ensures durability, precision, and conformity for spacing blocks in testing machines.

IS 14858 – Marking and Identification (Clause 9)

Key Specifications for Marking:

• Mandatory Markings on Machines (Clause 9.1):

  • Source of Manufacture: Manufacturer's name or trademark.
  • Date of Manufacture: Month and year.
  • Serial Number: Unique identifier for traceability.

• BIS Certification Marking (Clause 9.2):

  • Machines may bear the Standard Mark as per BIS guidelines.
  • Use of this mark is regulated under the Bureau of Indian Standards Act, 1986.
  • License for use of the Standard Mark must be obtained from BIS.

Summary Table:

Notes:

• Markings must be clear, indelible, and durable.
• Refer to BIS for licensing conditions on the Standard Mark.

flowchart TD
    A[Machine] --> B[Marking]
    B --> C[Source of Manufacture]
    B --> D[Date of Manufacture]
    B --> E[Serial Number]
    B --> F{BIS Standard Mark?}
    F -->|Yes| G[License from BIS]
    F -->|No| H[No BIS Mark]

This ensures traceability, quality assurance, and compliance with IS 14858.

IS 14858: Calibration and Verification Key Points

Verification Procedure (Clause 10.1 & 10.2)

• When to verify:

  • Periodically as per 10.1.1 to 10.1.3
  • Immediately if accuracy is doubted (10.1.3)

• Test Loads:

  • Apply 5 loads in 4 roughly equal ascending increments.
  • Successive load difference ≤ 1/3 of (max load - min load).

Error Calculation (Clause 10.2)

For each test point, record:

• A = Load indicated by test machine (N)
• B = Load from calibration device (N)

Calculate: [ E = A - B ] [ %E = \frac{E}{B} \times 100 ]

Specimen Space (Clause 4.3)

• Must accommodate an elastic calibration device covering the full load range.
• Device should be readable in the test position.

Summary Table: Load Increments

flowchart LR
    A[Start Verification] --> B[Apply 5 Loads in Ascending Order]
    B --> C[Record Load Indicated (A) and Applied Load (B)]
    C --> D[Calculate Error E = A - B]
    D --> E[Calculate % Error = (E/B)*100]
    E --> F{Is Error Acceptable?}
    F -- Yes --> G[Verification Passed]
    F -- No --> H[Recalibrate or Repair Machine]

This ensures precise calibration and reliable test results per IS 14858.

IS 14858: Record of Machine Performance - Key Specifications

• Surface Texture (Clause 7.6):
  The R value (surface roughness) of auxiliary platen contact faces must be between 0.4 µm and 3.2 µm.

• Machine Indicators (Clause 5.3.1):

  • Must have easily readable dials/scales or electrical load indicators with visual display.
  • Visual display can be supplemented by calibrated recording devices.
  • A resettable device must register the maximum load sustained by the specimen.
  • Needle width < width of scale graduation for accuracy.

• Machine Movement Rates (Clause 1.3):

  • Screw type machines: moving head speed ≈ 1.3 mm/min (idle).
  • Hydraulic machines: load applied at a rate corresponding to 0.14 to 0.324 MPa/s on specimen.

• Machine Markings (Clause 9.1):

  • Manufacturer source
  • Date of manufacture
  • Serial number

Summary Table: Machine Performance Parameters

flowchart TD
    A[Machine Setup] --> B[Check Surface Texture (0.4-3.2 µm)]
    B --> C[Calibrated Load Indicators]
    C --> D[Resettable Max Load Device]
    D --> E[Mark Machine Info (Manufacturer, Date, Serial)]
    E --> F[Set Moving Head Speed or Loading Rate]

This ensures accurate, reliable machine performance records per IS 14858.

IS 14858: Committee Composition - Key Points

• Committee Name: Cement and Concrete Sectional Committee, CED 2

• Composition: Includes representatives from:

  • Government research labs (e.g., Central Building Research Institute, Central Road Research Institute)
  • Industry (e.g., Cement Corporation of India Ltd, Gammon India Ltd)
  • Academic institutions (e.g., Indian Institute of Technology, Indian Institute of Science)
  • Public Works and Engineering Departments
  • Specialized agencies (e.g., Fly Ash Mission, Geological Survey of India)
  • Alternate members for each primary member ensure continuity.

• Annex A lists detailed members with their affiliations and alternates, ensuring broad expertise and representation.

Summary Table of Key Roles

Notes on Calibration (Clause 10.3) & Machine Performance (Clause 11)

• Verification reports must specify the loading range within which the machine conforms.
• Loading range must not include loads below 100 times the smallest load increment or below 10% of max capacity.
• Maintain detailed records of machine ID, purchase, installation, maintenance, and verification dates.

graph TD
    A[Committee Composition] --> B[Government Labs]
    A --> C[Industry Representatives]
    A --> D[Academic Institutions]
    A --> E[Public Works Departments]
    A --> F[Specialized Agencies]
    B --> G[CBRI, CRRI, CSIR]
    C --> H[Cement Corps, Gammon, L&T]
    D --> I[IIT, IISc]
    E --> J[CPWD, PWD]
    F --> K[Fly Ash Mission, Geological Survey]

This composition ensures comprehensive expertise for standard formulation in cement and concrete testing.