Precast concrete blocks for paving

IS 15658: Scope - Key Specifications & Dimensions

This standard covers concrete paver blocks with precise dimensional and quality controls.

Key Dimensions & Tolerances (Table 2 summary)

Measurement Reference

• All dimensions and tolerances measured as per Annex B (Clause 7.3) detailing length, width, thickness, aspect ratio, plan area, wearing face area, and squareness.

Aspect Ratio Formula

[ \text{Aspect Ratio} = \frac{L}{T} \leq 4.0 ]

Notes:

• Wearing face area should cover at least 75% of plan area to ensure durability.
• Arris/chamfer ensures edge protection.
• Squareness tolerance controls block fitment precision.

flowchart TD
    A[Specify Dimensions] --> B[Measure Length (L)]
    A --> C[Measure Width (W)]
    A --> D[Measure Thickness (T)]
   

IS 15658 — Key References, Tables & Specifications

1. Referenced Indian Standards (Annex A)

IS 15658 refers to multiple IS codes essential for materials and testing:

2. Dimensional Tolerances for Paver Blocks (Table 2, Clause 6.2.3)

3. Measurement

IS 15658: Definitions & Key Specifications for Paver Blocks

Key Dimensions & Formulas (Annex B & Table 2)

Measurement Methods (Annex B)

• Length (L), Width (W), Thickness (T) measured using steel rule (0.5 mm gradation), odd-leg marking gauge, and balance for precision.
• Aspect Ratio = Length / Thickness (max 4.0)
• Plan Area (A_SP) = L × W (max 0.03 m²)
• Wearing Face Area (A_SW) ≥ 75% of Plan Area
• Squareness deviation measured as gap between edges (tolerance ± 2 to 3 mm)

Summary Diagram for Dimensions

graph TD
    A[Length (L)] --- B[Width (W)]
    A --- C[Thickness (T)]
    B --- C
    D[Plan Area = L ×

IS 15658: Materials - Key Specifications & Formulas

1. Recommended Dimensions & Tolerances for Paver Blocks (Table 6.2.5)

2. Flexural Strength Calculation (Clause 3.2 & G-5)

[ f_o = \frac{P \times l}{b \times d^2} ]

• (f_o) = flexural strength (N/mm²)
• (P) = maximum breaking load (N)
• (l) = span length between supports (mm)
• (b) = average width of specimen (mm)
• (d) = average thickness of specimen (mm)

3. Suggested Minimum Breaking Loads (kN) for Applications (Table G-7)

IS 15658 - Manufacture: Key Specifications & Tables

Recommended Dimensions & Tolerances for Paver Blocks (Clause 6.2.3, Table 6.2.5)

Measurement Method (Annex B)

• Use steel rule (0.5 mm gradation), cardboard sheets, odd-leg marking gauge.
• Measure length, width, thickness, aspect ratio, plan area, wearing face area, and squareness as per Annex B.

Apparatus (Clause 3.1)

• Balance (accuracy 0.0001 N)
• Thin cardboard sheets
• Sharp pencil and scissors
• Odd-leg marking gauge
• Steel rule (0.5 mm gradations)

Summary Diagram: Dimension Measurement

flowchart LR
    A[Start] --> B[Measure Length (L)]
    B --> C[Measure Width (W)]
    C --> D[Measure Thickness (T)]
    D --> E[Calculate Aspect Ratio (L/T)]
    E --> F[Measure

IS 15658: Physical Requirements for Concrete Paver Blocks

Key Specifications & Tolerances (Table 2, Clause 6.2.3)

Measurement Methods

• Refer Annex B for determination of length, width, thickness, aspect ratio, plan area, wearing face area, and squareness.
• Wearing layer thickness per Clause 6.2.3.

Definitions

• Aspect ratio (L/T): Length divided by thickness, max 4.0 ensures block stability.
• Wearing face area: Portion of top surface designed to resist wear, minimum 75% of plan area.
• Squareness: Deviation from perfect right angle, controlled within tolerance limits.

Summary Diagram of Dimensions

graph TD
  A[Length (L)] --> B[Width (W)]
  B --> C[Thickness (T)]
  C --> D[Wearing Layer Thickness]
  B --> E[Plan Area (A

IS 15658: Testing Methods Key Points

1. Specimen Capping (Clause 3.2)

• Surface irregularities must be leveled by capping with sulphur or gypsum before testing.

2. Flexural Strength Test Procedure (Modified from IS 516 Clause 8)

• Load applied as a simple beam load via a roller at mid-span (Fig. 6 & 7).
• Load rate: 6 kN/min, applied smoothly without shock.
• Load increased until failure; record max load P (nearest 1 N).

3. Flexural Strength Calculation (Clause G-5)

[ f_o = \frac{P \times l}{b \times d^2} ]

Where:

• ( f_o ) = flexural strength (N/mm²)
• ( P ) = max breaking load (N)
• ( l ) = span length between supports (mm)
• ( b ) = specimen width (mm)
• ( d ) = specimen thickness (mm)

4. Minimum Breaking Load Values (Clause G-7)

5. Additional Testing Methods Referenced

• Compressive strength: IS 15658 Annex D (Clauses 6.2.5.1, 7.3)
• Tensile splitting strength: IS 15658 Clause 6.3.1

flowchart LR
    A[Specimen Preparation] --> B[Capping with Sulphur/Gypsum]
    B --> C[Load Application via Roller at Mid-span]
    C --> D[Load increased at 6 kN/min]
    D --> E[Specimen Failure & Max Load Recorded]
    E --> F[Calculate Flexural Strength: \(f_o = \frac{P l}{b d^2}\)]
    F --> G[Compare with

IS 15658 - Sampling for Paver Blocks (Clause 8.5 and Table 4)

Sampling Requirements Summary

* Blocks used for these tests may be reused for subsequent tests.

Notes:

• Numbers in brackets are additional samples to avoid secondary sampling if conformity tests require retesting.
• Sampling follows Clause 8 procedures; specimens must be from the same batch and shape/size/thickness group.
• Thickness of wearing layer test applies only to blocks with distinct layers.

Key Clauses:

• Clause 8.5: Sampling numbers per test.
• Clauses 1.2, 2.2, 3.2: Specimen selection criteria aligned with sampling.

This ensures statistically valid quality assurance for paver blocks per IS 15658.

IS 15658: Acceptance Criteria for Paver Blocks

Key Specifications & Tolerances (Clause 9 & Table 2)

Notes:

• Samples must be marked and protected from extreme conditions until testing (Clause 8.6).
• Tests should be conducted as soon as practicable after sampling.
• Optional requirements acceptance criteria are mutually agreed (Clause 9.2).
• Dimensional measurements follow Annex B methods.

Aspect Ratio Formula:

[ \text{Aspect Ratio} = \frac{L}{T} \leq 4.0 + 0.2 ]

flowchart LR
    A[Sampling of Paver Blocks] --> B[Marking & Protection]
    B --> C[Testing as soon as practicable]
    C --> D{Check Dimensions & Properties}
    D -->|Within Tolerance| E[Accept Consignment]
    D -->|

IS 15658: Marking - Key Points & Specifications

1. Use of Standard Mark (Clause 10.2.1)

• Governed by the Bureau of Indian Standards Act, 1986.
• Licence conditions for use of Standard Mark are regulated by BIS.
• Paver blocks may be marked with the Standard Mark (Clause 10.2).

2. Marking Details

• Marking ensures product conformity and traceability.
• Mark includes BIS Standard Mark and license number.

3. Measurement & Dimension Determination (Annex B, Clause 7.3)

• Length (L), Width (W), Thickness (Th) measured using:
  • Steel rule (0.5 mm accuracy)
  • Odd-leg marking gauge
  • Balance (accuracy 0.0001 N)
• Aspect ratio = Length / Thickness or Width / Thickness (depending on shape)
• Plan area and wearing face area determined by tracing block outline on cardboard.

4. Apparatus for Measurement (Clause 3.1)

• Balance (1 N capacity, 0.0001 N accuracy)
• Thin cardboard sheets
• Sharp pencil, scissors
• Odd-leg marking gauge
• Steel rule (0.5 mm gradations)

Summary Table for Marking and Measurement

flowchart LR
    A[Start: Paver Block] --> B[Measure Length, Width, Thickness]
    B --> C[Calculate Aspect Ratio]
    C --> D[Trace Outline on Cardboard]
    D --> E[Determine Plan & Wearing Face Area]
    E --> F[Mark with BIS Standard Mark + License No.]
    F --> G[Product Ready for Certification]

This ensures compliance with IS 15658 marking and measurement requirements.

IS 15658 - List of Referenced Indian Standards

This standard references key Indian Standards related to materials and testing for precast concrete blocks for paving. Below is a concise list of important IS codes referenced:

Additional references for testing and guidelines:

• AS/NZS 4456.5:1997 — Testing breaking load of segmental paving units.
• IRC SP-63-2004 — Guidelines for Interlocking Concrete Block Pavement.

Key Notes:

• Use of Standard Mark governed by BIS Act, 1986.
• Testing includes durability (e.g., freeze-thaw cycles with max 1% weight loss in NaCl solution).
• Refer to IS 2:1960 for rounding off numerical values.

flowchart LR
    A[IS 15658] --> B[Material Specifications]
    A --> C[Testing Methods]
    B --> D[IS 269, IS 383, IS 456, IS 3812]
    C --> E[IS 516, AS/NZS 4456.5, IRC SP-63]
    B --> F[Concrete Admixtures & Poz

IS 15658: Method for Determination of Dimensions and Squareness (Annex B)

Apparatus (Clause 4.1)

• Engineer’s square or profiled template
• Feeler gauges (accuracy ±0.1 mm)

Procedure for Squareness (Clause 4.3)

1. Place the square/template on the top or bottom surface of the block.
2. Bring the blade in contact with the vertical face.
3. Measure the clearance (gap) between the template and vertical face using feeler gauges at points 10 mm inside each top and bottom edge.
4. Repeat at six different locations around the block.
5. Calculate the average clearance as the deviation from squareness, recorded to ±0.1 mm.

Key Parameters to Report

• Length, Width, Thickness
• Aspect Ratio = Length / Width
• Plan Area = Length × Width
• Wearing Face Area (as applicable)
• Deviation from Squareness (average gap)

Summary Table (Example)

flowchart LR
    A[Place square/template on block surface] --> B[Contact blade with vertical face]
    B --> C[Measure clearance with feeler gauge at 10 mm inside edges]
    C --> D[Repeat at 6 locations]
    D --> E[Calculate average clearance = Deviation from Squareness]

This method ensures precise dimensional control and squareness verification per IS 15658 standards.

IS 15658: Method for Determination of Water Absorption (Clause 6.2.4 & Annex C)

Key Specifications:

• Specimens: Minimum 3 units, selected as per sampling (Clause 8) and Table 4.
• Balance Sensitivity: ±0.5% of smallest specimen mass.
• Limit:
  • Average water absorption ≤ 6% by mass
  • Individual specimen ≤ 7% by mass

Formula for Water Absorption (Clause 4.1, Annex C-4.1):

[ \text{Water Absorption } (W%) = \frac{W_w - W_a}{W_a} \times 100 ]

Where:

• (W_w) = Mass of specimen after water immersion (saturated mass)
• (W_a) = Mass of dry specimen (oven-dried mass)

Procedure Summary:

1. Oven dry specimens to constant mass ((W_a)).
2. Immerse in water for 24 hours.
3. Remove, surface dry, and weigh ((W_w)).
4. Calculate water absorption % using above formula.
5. Report individual and average values.

flowchart TD
    A[Select 3 Specimens] --> B[Oven Dry to Constant Mass (Wa)]
    B --> C[Immerse in Water for 24 hrs]
    C --> D[Surface Dry & Weigh (Ww)]
    D --> E[Calculate Water Absorption %]
    E --> F[Check Limits: Avg ≤ 6%, Individual ≤ 7%]

This ensures durability and quality compliance for concrete paver blocks per IS 15658.

IS 15658: Method for Determination of Compressive Strength

Key Steps (Clause 6.2.5.1 & Annex D)

• Loading Rate: Apply load continuously at 15 ± 3 N/mm²/min without shock until failure or delamination.
• Maximum Load (P): Record maximum load in Newtons (N).

Calculation (Clause D-5)

[ \text{Apparent Compressive Strength} = \frac{P \text{ (N)}}{\text{Plan Area (mm}^2)} ]

[ \text{Corrected Compressive Strength} = \text{Apparent Strength} \times \text{Correction Factor} ]

• Express strength to nearest 0.1 N/mm².

Correction Factors (Table 5)

• For thickness between 50-120 mm, linear interpolation of correction factor applies.

Summary Diagram

flowchart TD
    A[Specimen Preparation] --> B[Apply Load at 15±3 N/mm²/min]
    B --> C{Failure or Delamination?}
    C -- No --> B
    C -- Yes --> D[Record Max Load (N)]
    D --> E[Calculate Apparent Strength = Load / Area]
    E --> F[Apply Correction Factor (Table 5)]
    F --> G[Report Corrected Compressive Strength]

This method ensures accurate compressive strength considering block thickness and edge finish.

IS 15658: Abrasion Resistance Test for Paver Blocks

Method Summary (Annex E & Clause 6.2.6)

• Test machine: As per Annex F of IS 1237 (see Fig. 4), includes a rotating disc with water drops (180-200 drops/min, ~13 ml/min) to keep abrasive powder in motion.
• Specimen preparation: Clamped in a square frame (dimensions per Clause 3.5).
• Test cycle: 16 cycles; after each cycle:
  • Specimen rotated 90° clockwise.
  • 20 g of abrasive powder spread evenly on the track.

Key Formula for Abrasion Loss

[ AV = \frac{Am}{PR} ]

Where:

• Report abrasion loss as: nearest whole number per 1000 mm³ per 5000 mm² area.

Important Points

• Abrasive powder must continuously return to the track area.
• Water drops maintain abrasive action and cooling.
• The test evaluates durability and quality control of paver blocks.

flowchart LR
    A[Start Test] --> B[Clamp specimen in square frame]
    B --> C[Spread 20g abrasive powder]
    C --> D[Run 1 cycle: rotate disc & specimen]
    D --> E[Rotate specimen 90° clockwise]
    E --> F{Repeat 16 cycles?}
    F -- Yes --> C
    F -- No --> G[Measure mass loss Am]
    G --> H[Calculate volume loss AV = Am / PR]
    H --> I[Report abrasion resistance]

This method ensures standardized abrasion resistance measurement for paver blocks per IS 15658.