Methods of sampling of clay building bricks

IS 5454: Scope - Key Sampling & Conformity Specifications

Scope Summary:

• Applies to sampling and testing of bricks for physical, visual, and dimensional characteristics.
• Sampling sizes and permissible defectives depend on lot size.
• For lots ≤ 2000 bricks, sampling is by agreement between purchaser and supplier.

1. Sampling for Visual & Dimensional Characteristics (Table 1, Clause 4.2)

2. Sampling for Physical Characteristics (Table 2, Clause 5.2.3)

Notes:

• Test results rounding as per IS 2:1960.
• Sampling ensures quality control based on lot size and defect tolerance.

flowchart TD
    A[Lot Size] --> B{2,001 to 10,000}
    A --> C{10,001 to 35,000}
    A --> D{35,001 to 50,000}
    
    B --> E[Visual Sample: 20 bricks, Defectives ≤ 1]
    B --> F

IS 5454 - Definitions & Sampling Specifications

Key Definitions (Clause 2.0)

• Standard definitions apply for bricks, characteristics, defects, etc., as per IS 5454.
• Sampling and conformity criteria are based on lot size.

Sampling & Conformity Tables

Notes

• For lots ≤ 2,000 bricks, sampling is by mutual agreement.
• Test results rounding as per IS 2:1960.

flowchart TD
    A[Lot Size] --> B{Lot Size Range}
    B -->|2,001-10,000| C[Sample Size: 5 (Physical), 20 (Visual)]
    B -->|10,001-35,000| D[Sample Size: 10 (Physical), 32 (Visual)]
    B -->|35,001-50,000| E[Sample Size: 15 (Physical), 50 (Visual)]
   

IS 5454: Methods of Sampling for Bricks

Key Points from IS 5454:

• Sampling Methods (Clause 3.1):

  • (a) Random Sampling
  • (b) Stratified Sampling (per IS: 4905-1968)

• Sampling from Lorries/Trucks (Clause 3.2.3):

  • Sample bricks must be drawn from at least 10 lorries/trucks (if possible).
  • Equal number of bricks from each vehicle to meet total sample size.

• Average Definition (Clause 2.4): [ \text{Average} = \frac{\sum \text{observations}}{\text{number of observations}} ]

• Scale of Sampling (Clause 4.1.1):

  • Number of bricks selected depends on lot size.
  • Use Table 1 for:
    • Visual characteristics (columns 1 & 2)
    • Dimensional characteristics (columns 1 & 4) if specified.
  • Sampling follows methods in Clause 3.

Typical Sampling Table Format (Example):

(Note: Refer IS 5454 Table 1 for exact values.)

Summary:

• Use random or stratified sampling.
• Draw samples from multiple vehicles if bricks come from trucks.
• Determine sample size based on lot size using Table 1.
• Calculate averages for test results as per Clause 2.4.

flowchart TD
    A[Start Sampling] --> B{Is lot from multiple trucks?}
    B -- Yes --> C[Select bricks equally from ≥10 trucks]
    B -- No --> D[Select bricks from lot as per Table 1]
    C --> E[Apply Random/Stratified Sampling]
    D --> E

IS 5454: Scale of Sampling & Criteria for Conformity (Visual & Dimensional Characteristics)

1. Sampling & Acceptance Criteria (Clause 4.2 & Table 1)

• If defective bricks ≤ permissible number → Lot accepted.
• If defective bricks > permissible number → Lot rejected.
• For lots ≤ 2,000 bricks, sampling is by mutual agreement.

2. Dimensional Characteristics (Clause 4.3.1)

• Same sampling & acceptance criteria as visual characteristics for individual bricks.

3. Sampling from Trucks (Clause 3.2.3)

• Sample bricks should be taken from at least 10 trucks, equal number from each.

Summary Table for Visual & Dimensional Sampling

| Lot Size        | Sample Size (Visual & Dimensional) | Max Defectives Allowed |
|-----------------|-----------------------------------|-----------------------|
| 2,001 - 10,000  | 20                                | 1                     |
| 10,001 - 35,000 | 32                                | 2                     |
| 35,001 - 50,000 | 50                                | 3                     |

This ensures quality control by statistically verifying batches for visual and dimensional conformity.

IS 5454: Scale of Sampling & Criteria for Conformity for Physical Characteristics

1. Sampling for Physical Characteristics (Clause 5.2.3, Table 2)

• For lots ≤ 2000 bricks, sampling is by mutual agreement.

2. Sampling for Visual & Dimensional Characteristics (Clause 4.2, Table 1)

• For dimensional characteristics, bricks are divided into groups of 20; all groups must meet specs.

3. Sampling from Trucks (Clause 3.2.3)

• Sample bricks must be taken from ≥10 trucks, equally distributed, to ensure representativeness.

Summary:

• Sample size and permissible defectives increase with lot size.
• Visual and dimensional inspections have separate sampling criteria.
• Physical tests include strength, density, absorption, efflorescence, and warpage.

IS 5454: Reporting and Interpretation of Results - Key Points

1. Rounding Off Results

• Follow IS:2-1960 for rounding off final observed or calculated values.

2. Sampling & Criteria for Conformity

Note: For lots ≤ 2,000 bricks, sampling is by mutual agreement.

3. Visual & Dimensional Characteristics Sampling

4. Average Calculation

[ \text{Average} = \frac{\sum \text{Observations}}{\text{Number of Observations}} ]

Summary Flow for Reporting

flowchart TD
    A[Select Lot Size] --> B{Determine Sample Size}
    B --> C[Perform Physical Tests]
    B --> D[Perform Visual & Dimensional Tests]
    C --> E{Check Defectives ≤ Permissible?}
    D --> F{Check Defectives ≤ Permissible?}

IS 5454: Notes on Sampling from Transport Vehicles

Key Specifications & Methods

• Clause 3.2.3: Sampling from Lorries/Trucks

  • Sample bricks must be drawn from not less than 10 lorries/trucks (if possible).
  • Equal number of bricks are taken from each vehicle to meet total sample size.

• Clause 3.2.1: Sampling in Motion

  • Sample bricks should be taken while bricks are moving (loading/unloading).
  • Divide the lot into ≥10 portions.
  • Draw approximately equal bricks from each portion at regular intervals.

• Clause 3.1: Sampling Methods

  • Use either:
    • Random Sampling
    • Stratified Sampling as per IS 4905-1968.

Sampling Formula for Average (Clause 2.4)

[ \text{Average} = \frac{\sum \text{Observations}}{\text{Number of Observations}} ]

Summary Table for Sampling from Vehicles

flowchart LR
    A[Start Sampling] --> B{Are bricks moving?}
    B -- Yes --> C[Divide lot into ≥10 portions]
    C --> D[Draw equal bricks at intervals]
    B -- No --> E[Random or Stratified Sampling]
    D --> F[Sample from ≥10 vehicles]
    E --> F
    F --> G[Perform inspection & testing]

This ensures representativeness and conformity in brick quality inspection per IS 5454.

IS 5454: Key Tables & Sampling Specifications (Annexures)

Table 2: Scale of Sampling & Criteria for Physical Characteristics

• Note: For lots ≤ 2000 bricks, sampling is by mutual agreement.

Key Points:

• Warpage defects must not exceed permissible defectives in column 5.
• Sampling covers physical tests: compressive strength, breaking load, transverse strength, bulk density, water absorption, and efflorescence.
• Sampling size and acceptance criteria increase with lot size.

This table ensures quality control by defining sample sizes and acceptable defect limits for brick physical characteristics per IS 5454.