Methods of sampling hydraulic cement

IS 3535: Scope - Key Specifications & Sampling

Scope Summary:

IS 3535 covers the sampling, inspection, and testing of cement and related materials (clinker, pozzolana). It defines:

• Sampling methods for quality control during production.
• Inspection levels for routine control.
• Acceptance criteria for test results.

Key Clauses & Tables:

1. Inspection Frequency (Clause 4.1, Table 4.2)

2. Acceptance Criteria (Clause 9.3.2)

If the characteristic has a minimum limit, calculate:

[ \text{Value} = \bar{X} - 0.5R ]

• (\bar{X}) = average of test results
• (R) = range of test results

If Value ≥ Minimum limit, lot is accepted.

3. **Sampling Sub

IS 3535 - Key Definitions & Formulas for Quality Control

Definitions (Clause 2.0)

• Standard definitions apply to test results, lot conformity, and characteristic limits.

Important Formulas (Clauses 5.9.3.1, 5.9.3.2, 5.9.3.3)

Usage Summary

• Calculate average (x) and range (R) from test data.
• Use these values to verify if the lot meets minimum or maximum specification limits.
• This method accounts for variability by incorporating half the range into conformity checks.

flowchart TD
    A[Test Results] --> B[Calculate Average (x)]
    A --> C[Calculate Range (R)]
    B --> D{Check Limit Type}
    C --> D
    D -->|Minimum Limit| E[Calculate x - 0.5R]
    D -->|Maximum Limit| F[Calculate x + 0.5R]
    E --> G{Is value ≥ min limit?}
    F --> H{Is value ≤ max limit?}
    G -->|Yes| I[Lot Conforms]
    G -->|No| J[Lot Does Not Conform]
    H -->|Yes| I
    H -->|No| J

This approach ensures statistical confidence in lot acceptance per IS 3535.

IS 3535: General Sampling Principles

Key Clauses and Specifications:

1. Sampling Instrument & Environment (Clause 3.1)

• Use clean, dry instruments.
• Prevent contamination of sample, material, and containers.
• Containers should be almost fully filled, airtight sealed, and marked with material details and sampling date.
• Store samples at stable temperatures.
• Sampling area must be clean, dry, and draft-free.

2. Sub-Lots for Sampling (Clause 5.2.1)

• Divide a lot during conveyor discharge into sub-lots as per Table 2 (refer IS 3535 Table 2 for sub-lot sizes).
• Ensures representative sampling over the entire lot.

3. Sample Preparation (Clause 5.7.1)

• Mix gross sample thoroughly.
• Break lumps and remove foreign materials.
• Pass sample through 850-micron IS sieve.
• Discard lumps that do not break or foreign materials.

Statistical Quality Control References:

• Use control charts for variables and attributes (as per IS statistical quality control methods Parts 1, 2, and 3).

Summary Table: Sample Preparation Steps

flowchart TD
    A[Lot on Conveyor] --> B[Divide into Sub-lots (Table 2)]
    B --> C[Draw Gross Sample]
    C --> D[Mix Thoroughly]
    D --> E[Break Lumps]
    E --> F[Pass through 850-micron IS Sieve]
    F --> G[Discard Foreign Materials & Hard Lumps]
    G --> H[Prepare Final Sample]

This ensures representative, uncontaminated samples for reliable testing per IS 3535.

IS 3535 - Process Inspection Key Points

1. Sampling & Sub-Lots (Clause 5.2.1)

• When discharging cement over a conveyor, divide the lot into sub-lots as per Table 2 (not provided here).
• This segmentation aids in systematic sampling during production.

2. Increment Drawing Interval (Clause 3.2)

• Sampling increments should be drawn at uniform mass intervals throughout the lot.
• If material handling rate is uniform, increments can be based on time intervals instead of quantity.

3. Inspection Objective (Clause 4.1)

• Manufacturer's inspection: Ensure uniformity and minimize quality fluctuations.
• Take representative samples at regular intervals for process control.
• Use inspection levels from Table 1 for routine quality control (details in IS 3535).

4. Statistical Quality Control (Clause 4.2.4)

• Recommended to use Statistical Quality Control (SQC) techniques:
  • IS 397 (Part 1, 2, 3) covers control charts for variables, attributes, and special charts.
• Helps monitor and control quality fluctuations during production.

Summary Table (Conceptual)

flowchart LR
    A[Lot] --> B[Divide into Sub-lots (Table 2)]
    B --> C[Draw increments at uniform mass/time]
    C --> D[Sample & Inspect at regular intervals (Table 1)]
    D --> E[Apply SQC techniques (IS 397)]
    E --> F[Control quality fluctuations]

Use IS 3535 with IS 397 series for effective process inspection and quality control.

IS 3535 Sampling Procedures Summary

1. Division of Lot into Sub-Lots (Clause 5.2.1 & Table 2)

• A lot discharged over a conveyor is divided into sub-lots for sampling.
• Number of sub-lots depends on lot weight as per above table.

2. Sampling Methods (Clause 4.2)

• Samples should be drawn using clean, dry instruments.
• Avoid contamination of sample, material, and containers.
• Containers must be nearly full, sealed airtight, and labeled with material details and sampling date.
• Store samples at stable temperature, avoiding undue variation.
• Sampling location must be clean, dry, and draught-free.

3. Precautions in Sampling (Clause 3.1)

• Use clean, dry sampling tools.
• Protect samples from contamination.
• Seal and label samples properly.
• Maintain sample temperature and storage conditions.

flowchart TD
    A[Lot Discharged Over Conveyor] --> B[Divide into Sub-Lots]
    B --> C{Weight of Lot}
    C -->|Up to 100t| D[2 Sub-Lots]
    C -->|101-200t| E[3 Sub-Lots]
    C -->|201-300t| F[4 Sub-Lots]
    C -->|301-500t| G[5 Sub-Lots]
    C -->|501-1000t| H[6 Sub-Lots]
    C -->|1001-2000t| I[7 Sub-Lots]
    D & E & F & G & H & I --> J[Sampling from Each Sub-Lot]
    J --> K[Prepare & Store Samples as per Clause 3.1]

This ensures statistically representative sampling and quality control during production.

IS 3535: Sampling from Conveyors (Clauses 5.2 & 5.5.2)

1. Division of Lot into Sub-Lots (Clause 5.2.1 & Table 2)

2. Gross Sample Collection (Clause 5.2.2)

• Increment frequency: 1 increment per every 10 tonnes or part thereof.
• Increment weight: ≥ 2 kg.
• Sampling method:
  • Preferably take increment across full cross-section and thickness of the material stream.
  • Use a receptacle cutting across the entire stream at discharge.
  • If not possible, use a scoop on moving belt (stop conveyor if practicable).
• Purpose: Ensure sufficient sample quantity for testing as per Clause 5.7.

Summary Workflow:

flowchart TD
    A[Lot on Conveyor] --> B[Divide into sub-lots as per Table 2]
    B --> C[Collect increments: 1 per 10 tonnes]
    C --> D[Each increment ≥ 2 kg]
    D --> E[Combine increments to form gross sample]
    E --> F[Use for testing]

This ensures representative sampling for quality control during material discharge on conveyors.

IS 3535 - Sampling from Bulk Storage (Silos) - Clause 5.3

Key Specifications:

• Sampling Method: Divide the bulk stored in silos into sub-lots based on total lot weight.
• Number of Sub-Lots: Refer to Table 5.2 (Clause 5.5.2) for dividing the lot into sub-lots.

Sampling Procedure Highlights:

• Each sub-lot is sampled individually.
• Samples from sub-lots are combined to form a composite sample.
• Sampling should be random and representative of the entire silo content.

Summary Diagram:

flowchart TD
    A[Bulk Storage in Silo] --> B[Divide into Sub-Lots]
    B --> C{Weight of Lot}
    C -->|Up to 100t| D[2 Sub-Lots]
    C -->|101-200t| E[3 Sub-Lots]
    C -->|201-300t| F[4 Sub-Lots]
    C -->|301-500t| G[5 Sub-Lots]
    C -->|501-1000t| H[6 Sub-Lots]
    C -->|1001-2000t| I[7 Sub-Lots]
    D & E & F & G & H & I --> J[Sample Each Sub-Lot]
    J --> K[Combine Samples for Composite Sample]

This ensures statistically valid and representative sampling from bulk silos as per IS 3535.

IS 3535 - Sampling from Ship's Hold (Clause 5.4 & 5.4.1)

• Sub-Lots Division: Cement quantity in the ship's hold is divided into sub-lots based on total weight.
• Table 2 (Sub-Lots Based on Lot Weight):

• Sampling Procedure:

  • Each sub-lot is sampled separately.
  • Samples from sub-lots are combined proportionally for composite testing.

• Purpose: Ensures representative sampling reflecting variability within the ship's hold.

Additional Notes:

• Sampling must be random and avoid contamination.
• Use clean, dry sampling tools.
• Follow IS 3535 Clause 5.4 for detailed procedural steps.

flowchart TD
    A[Ship's Hold Cement Lot] --> B{Weight of Lot?}
    B -->|Up to 100t| C[1 Sub-Lot]
    B -->|100-200t| D[2 Sub-Lots]
    B -->|200-400t| E[4 Sub-Lots]
    B -->|400-800t| F[8 Sub-Lots]
    B -->|Above 800t| G[16 Sub-Lots]
    C --> H[Sample each Sub-Lot]
    D --> H
    E --> H
    F --> H
    G --> H
    H --> I[Combine samples proportionally]
    I --> J[Composite Sample for Testing]

This ensures systematic, representative sampling from ship's holds as per IS 3535.

IS 3535: Sampling from Wagons (Clause 5.5)

• Increment Sampling (5.5.3.1):

  • From each selected wagon, take approximately equal number of increments.
  • Each increment weight ≥ 2 kg.
  • Sampling may be done in 2 or 3 operations.
  • Ensure total sample quantity suffices tests as per Clause 5.7.

• Gross Sample (5.5.3):

  • Use a slotted tube-sampler, ~60 cm length (Fig. 1 design).
  • Take samples from at least six evenly distributed points in each wagon.
  • Sample from a sub-lot basis.

• Sampler Design:

  • Slotted tube allows representative sampling from bulk material.
  • Sampling method aligns with 5.4.2 (detailed procedure for using the sampler).

Summary Table for Sampling from Wagons

flowchart LR
    A[Select Wagon] --> B[Identify 6 evenly distributed points]
    B --> C[Use 60 cm slotted tube-sampler]
    C --> D[Take increments ≥ 2 kg each]
    D --> E[Collect equal number of increments]
    E --> F[Combine increments to form gross sample]
    F --> G[Ensure sample quantity per Clause 5.7]

This ensures representative, sufficient sampling for quality testing per IS 3535.

IS 3535 - Sampling from Bags (Clause 5.6)

Key Specifications:

• Gross Sample Size (5.6.2):
  [ \text{Number of bags to sample} = \max \left( 5, \lceil 0.02 \times N \rceil \right) ] where

  • (N) = total bags in sub-lot
  • (\lceil \cdot \rceil) = next higher integer if fractional

• Random Selection Procedure (5.6.2.1):

  1. Assign sequential numbers to all bags: 1, 2, ..., (N).
  2. Calculate interval (r = \frac{N}{n}), where (n) is number of bags to sample.
  3. Round down (r) to integral part if fractional.
  4. Starting from a randomly selected bag, pick every (r^{th}) bag until (n) bags are selected.

• Random Number Table:
  Use IS:4905-1968 for random number tables if available.

Summary Table:

flowchart TD
    A[Start: Total bags = N] --> B[Calculate sample size n = max(5, ceil(0.02*N))]
    B --> C[Calculate interval r = floor(N/n)]
    C --> D[Select random start bag s]
    D --> E[Select bags s, s+r, s+2r, ..., until n bags selected]
    E --> F[End: Representative sample collected]

This ensures statistically representative sampling from bagged materials as per IS 3535.

IS 3535: Sample Reduction and Preparation (Clause 5.7)

• Initial Preparation:

  • Thoroughly mix the gross sample.
  • Break lumps and remove foreign materials.
  • Pass the material through an 850-micron IS sieve.
  • Discard hardened lumps that do not break on sieving/brushing and foreign materials.

• Sample Reduction Methods:

  • Use sample splitter or riffle samplers (Clause 5.7.2.1) for mechanical reduction.
  • Ensure random sampling to maintain representativeness.

• Final Sample Size:

  • Continue reduction until a laboratory sample of 11 kg is obtained (Clause 5.7.3).

Summary Table:

flowchart TD
    A[Gross Sample] --> B[Mix & Break Lumps]
    B --> C[Pass through 850-micron IS Sieve]
    C --> D{Remove Foreign Materials & Hardened Lumps}
    D --> E[Use Sample Splitter / Riffle Sampler]
    E --> F[Reduce Sample to 11 kg for Lab Testing]

This ensures a representative, manageable sample size for accurate testing.

IS 3535: Testing of Composite and Laboratory Samples - Key Points

1. Composite Sample Definition (Clause 2.7)

• Composite Sample = Equal quantities mixed from each laboratory sample representing sub-lots of a lot.

2. Testing Requirement (Clause 5.8.2)

• All requirements must be tested on the composite sample.

3. Sampling & Testing Frequency (Clause 4.1, Table 4.2)

4. Additional Notes

• Physical tests on laboratory samples prepared by ball milling clinker with additives per relevant specs.
• Composite samples represent the lot quality for all tests.

Visual Summary of Sampling & Testing Flow

flowchart TD
    A[Lot divided into Sub-lots] --> B

IS 3535: Criteria for Conformity (Clause 5.9)

For a lot to conform to specified requirements based on test results:

• Minimum Specification Limit: [ \bar{x} - 0.5 R \geq \text{Minimum limit} ] Where:

  • (\bar{x}) = Mean of test results
  • (R) = Range of test results

• Maximum Specification Limit: [ \bar{x} + 0.5 R \leq \text{Maximum limit} ]

• Two-sided Specification Limits: [ \text{Lower limit} \leq \bar{x} - 0.5 R \quad \text{and} \quad \bar{x} + 0.5 R \leq \text{Upper limit} ]

If these conditions are met, the lot is declared conforming.

Summary Table:

This method accounts for variability (range) in test results to ensure quality compliance.

If you need further details or tables, please specify!

IS 3535: Recommended Inspection Levels & Sampling Tables

1. Recommended Inspection Levels (Table 1, Clause 4.1)

Note: Samples for physical tests are prepared in a lab ball mill with additives as per relevant specs.

2. Sampling Sub-Lots (Table 2, Clause 5.2.1 & 5.5.2)

Summary:

• Sampling frequency varies by test and production stage.
• Lots are divided into sub-lots based on weight for representative sampling.
• Sampling ensures **