Methods of test for aggregates for concrete, Part 4: Mechanical properties

IS 2386 Part 4 — Scope & Key Specifications

This part covers methods for determining the aggregate crushing value (ACV), assessing aggregate strength.

Key Specifications & Equipment

• IS Sieves: Sizes 12.5 mm, 10 mm, and 2.36 mm are used for sample preparation and grading.
• Compression Testing Machine:
  • Capacity: 40 to 50 tonnes
  • Loading Rate: Uniform, reaching max load in 10 minutes
  • May have spherical seating or not.
• Sample Measure:
  • Cylindrical metal measure with:
    • Diameter = 11.5 cm
    • Height = 18.0 cm

Important Formula (Clause 3.5)

For calculating the load required (simplified):

[ \text{Load} = \text{Area} \times \text{Stress} ]

Where:

• Area = cross-sectional area of the specimen
• Stress = design or test stress

Table: Sample Dimensions

flowchart TD
    A[Sample Preparation] --> B[Sieving with 12.5, 10, 2.36 mm sieves]
    B --> C[Fill cylindrical measure (11.5cm dia x 18cm height)]
    C --> D[Compression Testing Machine]
    D --> E[Apply uniform load (40-50 tonnes) in 10 min]
    E --> F[Determine Aggregate Crushing Value]

Summary: Use specified sieves and sample measure; apply load uniformly with specified machine capacity; use formula in 3.5 for load calculations.

Aggregate Crushing Value (ACV) - IS 2386 (Part 4)

1. Sample Preparation (Clause 2.3 & Table I)

• Standard size: Aggregate passing 12.5 mm IS sieve and retained on 10 mm IS sieve.
• For other nominal sizes, use Table I:

2. Test Apparatus (Clause 2.36)

• Compression testing machine: Capacity 40 tonnes, uniform loading to max load in 10 minutes.
• Cylindrical measure: Diameter 11.5 cm, Height 18.0 cm.

3. Aggregate Crushing Value Formula

[ \text{ACV} = \left( \frac{\text{Weight of fines passing 2.36 mm sieve after crushing}}{\text{Total weight of sample}} \right) \times 100 ]

• ACV gives relative resistance to crushing.
• If ACV ≥ 30%, use 10% Fines Value test due to possible anomalies.

4. Notes

• Standard test on 12.5 - 10 mm fraction.
• Results for other sizes are not directly comparable.
• ACV is a percentage; lower values indicate stronger aggregates.

flowchart TD
    A[Prepare Sample] --> B[Fill Cylinder (11.5 cm dia, 18 cm height)]
    B --> C[Apply Load Grad

Determination of Ten Percent Fines Value (IS 2386 Part 4)

Objective

• Measures resistance of coarse aggregates to crushing.
• Applicable to all aggregates.

Equipment & Sample

• IS Sieves: 12.5 mm, 10 mm, 2.36 mm.
• Compression Testing Machine: Capacity 0.5 to 50 tonnes, load applied uniformly over 10 minutes.
• Cylindrical Metal Measure: Diameter = 11.5 cm, Height = 18.0 cm.

Procedure Summary

• Apply load ( x ) tonnes.
• Measure percentage fines ( y ) from two tests.
• Calculate load for 10% fines using:

[ \text{Load for 10% fines} = y + 4 \times 14 \times x ]

Where:

• ( x ) = load in tonnes,
• ( y ) = mean percentage fines at load ( x ).

Notes

• The test load is adjusted to find the load causing exactly 10% fines.
• Ensure uniform loading rate (max load in 10 minutes).

flowchart TD
    A[Sample Preparation] --> B[Apply Load \(x\) tonnes]
    B --> C[Measure % Fines \(y\)]
    C --> D[Calculate Load for 10% Fines]
    D --> E[Result: Ten Percent Fines Value]

This method quantifies aggregate crushing strength, critical for concrete and road construction quality control.

Aggregate Impact Value (AIV) - IS 2386 Part 4

Purpose

• Measures resistance of coarse aggregate to sudden shock/impact (Clause 4.1).

Key Formula (Clause 4.5)

[ \text{Aggregate Impact Value (AIV)} = \left(\frac{B}{A}\right) \times 100 ]

• A = Weight of oven-dried sample (g)
• B = Weight of fraction passing 2.36 mm IS sieve after impact (g)

Procedure Highlights

• Test involves subjecting aggregate to impact and sieving.
• Fines passing 2.36 mm sieve are weighed (B).
• Calculate AIV as % fines of original sample weight (A).

Reporting (Clauses 3.6 & 4.6)

• Report load causing 10% fines to nearest whole number or 0.5 tonne (depending on load).
• Report mean of two test results as AIV, rounded to nearest whole number.

Summary Table

flowchart TD
    A[Oven-dried Sample (A)] --> B[Impact Test]
    B --> C[Sieve through 2.36 mm]
    C --> D[Weight fines (B)]
    D --> E[Calculate AIV = (B/A)*100]
    E --> F[Report mean of two tests]

This provides a relative measure of aggregate toughness under impact conditions per IS 2386 (Part 4).

IS 2386 (Part 4) - Aggregate Abrasion Value

1. Methods for Abrasion Value (Clause 5.1)

• (a) Deval Machine (Clause 5.2)
• (b) Los Angeles Machine (Clause 5.3) — Preferred method

2. Test Sample Gradings for Deval Machine (Clause 5.2.4)

3. Reporting Results (Clause 4.6)

• Perform two tests.
• Report the mean value to the nearest whole number as the Aggregate Abrasion Value.

4. Additional Notes

• The test sample must be dry coarse aggregate.
• The grading selected should represent the actual aggregate gradation used in the work.

Summary Formula for Abrasion Value (Deval Machine)

[ \text{Abrasion Value} = \frac{\text{Weight of fines generated}}{\text{Initial weight of sample}} \times 100 ]

flowchart TD
   

IS 2386 Part 4: Polished Stone Value (PSV) - Key Points

Objective

• Measures the relative polishing resistance of roadstone under traffic.
• Results are comparative; no fixed limits specified.

Test Procedure

1. Polishing: Samples are polished in an accelerated polishing machine.
2. Friction Measurement: Polished samples tested for friction coefficient.

Specimen Preparation (Clause 6.4.2)

• Particles per specimen: 40-50.
• Area covered: 90.5 × 44.5 mm.
• Mounting: In sand-cement mortar, particles exposed and flat on shorter dimension, curved on longer with 400 mm radius.
• Thickness: ≥ 12.5 mm.
• Specimen shape: Fits on a 405 mm diameter polishing wheel.
• Number of specimens: Minimum 2 per material.

Reporting (Clauses 5.3.5 & 6.9)

• Percentage wear:
  [ \text{Percentage Wear} = \frac{\text{Original Weight} - \text{Final Weight}}{\text{Original Weight}} \times 100 ]
• Polished Stone Value (PSV): Mean of two friction coefficients, expressed as a percentage, rounded to nearest whole number.

Summary Table

flowchart TD
    A[Sample Preparation] --> B[Mount particles in mortar]
    B --> C[Polishing in machine]
    C --> D[Friction Test]
    D --> E[Calculate PSV (% friction mean)]
    E --> F[Report results]

This test ensures the stone's resistance to polishing and skidding potential is quantified for road surface design.

IS 2386 (Part 4) - Determination of Crushing Strength of Aggregates

Test Procedure (Clause 7.4.1)

• Test type: Direct compression on cylindrical specimens.
• Loading rate: ~5 tonnes/minute.
• Specimen: Cylindrical aggregate compacted sample.
• Measure: Final load causing crushing.

Key Formula

[ \text{Crushing Strength (Stress)} = \frac{\text{Load at failure (kgf)}}{\text{Cross-sectional area (cm}^2\text{)}} ]

• Load in kgf (or tonnes converted to kgf)
• Area = (\pi \times (d/2)^2), where (d) = internal diameter of cylinder.

Dimensions of Test Cylinder (Clause 7.6 & Key to Dimensions)

Reporting (Clause 7.6)

• Report crushing stress for each specimen to nearest 5 kg/cm².
• Report average crushing stress.
• Note any defects (seams, fissures).

Summary Table for Crushing Strength Calculation

flowchart TD
    A[Test Specimen Preparation] --> B[Apply Compression Load]
    B --> C[Measure Load at Failure]
    C -->

IS 2386 Part 4: Key Apparatus Specifications

1. Impact Testing Machine (Clause 4.2 & 7.2)

• Total weight: 45 to 60 kg
• Metal base: 22 to 30 kg; plane lower surface ≥ 30 cm diameter
• Support: On level concrete/stone block ≥ 45 cm thick, fixed or on metal plate to prevent rocking
• Steel cup internal dimensions:
  • Diameter = 102 mm
  • Depth = 50 mm

2. Compaction Apparatus (Clause 2.2)

• Steel cylinder: Open-ended, diameter = 150 mm
• Tamping rod: Circular, diameter = 16 mm, length = 45–60 cm, rounded end
• Balance: Capacity 3 kg, accuracy 1 g

3. Los Angeles Abrasion Testing Machine (Clause 5.3.1)

• Cylinder: Hollow steel, inside diameter = 700 mm, length = 500 mm
• Rotation: Horizontal axis, with stub shafts
• Shelf: Steel shelf projecting radially 88 mm, full length of cylinder
  • Distance from shelf to opening ≥ 1250 mm (measured along circumference)
• Cover: Dust-tight, maintains cylindrical contour
• Shelf design: Prefer wear-resistant steel plate (25×500 mm) or angle section (200×100×12 mm)
• Wall thickness: Steel wall ≥ 12 mm
• Motor power: ≥ 1 HP recommended

4. Sieves

• IS Sieve size: 1.70 mm

Summary Table

flowchart LR
    A[Impact Testing Machine] -->|Weight 45-60 kg|

IS 2386 Part 4: Preparation of Test Samples

Key Specifications & Procedures

• Drying:
  Aggregate must be oven-dried at 105–110°C to constant weight (Clause 5.3.3).

• Sample Size & Gradings (Table II):

±2% tolerance on sample weight allowed.

• Particle Size for Specimens (Clause 6.4 & 3.3):
  • Use particles passing 12.5 mm IS sieve and retained on 10 mm IS sieve.
  • Particles should be clean, dust-free, non-flaky, and non-elongated.
  • Minimum 3 kg of 10-mm particles per test.

Summary Flow for Sample Preparation

flowchart TD
    A[Collect Aggregate] --> B[Dry at 105-110°C to constant weight]
    B --> C[Separate on IS sieves (12.5 mm & 10 mm)]
    C --> D[Select particles passing 12.5 mm & retained on 10 mm]
    D --> E[Ensure particles are clean, non-flaky, non-elongated]
    E --> F[Weigh test sample as per Table II grading]
    F --> G[Proceed with testing]

This ensures consistency and representativeness of aggregate samples in testing per IS 2386 (Part 4).

IS 2386 Part 4 — Test Procedures Summary

Key Equipment & Sample Preparation (Clauses 4.4, 2.36, 5.3.3)

• Sieves: IS sizes 12.5 mm, 10 mm, 2.36 mm for grading and fines determination.
• Compression Testing Machine: Capacity 0.5 to 50 tonnes; uniform loading reaching max load in 10 min.
• Sample Measure: Cylindrical metal, Diameter = 11.5 cm, Height = 18 cm.
• Sample Drying: Oven dry at 105–110°C to constant weight.
• Test Sample Gradings: Use gradings A to G per Table II below.

Table II: Test Sample Gradings & Weights (g)

IS 2386 Part 4 - Key Calculations and Specifications

1. Load Calculation (Clause 3.5)

• Load required can be calculated using the formula (as per Clause 3.5):

  [ \text{Load} = \text{Stress} \times \text{Cross-sectional Area} ]

2. Stress Calculation (Clause 7.5)

• Stress (kg/cm²) is calculated by dividing the load (kg) by the cross-sectional area (cm²):

  [ \sigma = \frac{P}{A} ]

  Where:

  • (\sigma) = stress (kg/cm²)
  • (P) = load applied (kg)
  • (A) = cross-sectional area (cm²)

3. Specimen Dimensions (Clause 2.36)

• Cylindrical metal measure for sample:
  • Diameter: 11.5 cm
  • Height: 18.0 cm

4. Equipment Specifications

• Compression testing machine:
  • Capacity: 0.5 to 50 tonnes
  • Uniform loading rate to reach max load in 10 minutes

5. IS Sieves for Fines Value Test (Clause 2.36)

• Sizes: 12.5 mm, 10 mm, 2.36 mm

Summary Table: Sample Cylinder Dimensions

flowchart TD
    A[Sample Preparation] --> B[Measure Sample in Cylinder]
    B --> C[Apply Load in Compression Testing Machine]
    C --> D[Record Maximum Load]
    D --> E[Calculate Stress = Load / Area]
    E --> F[Determine Ten Percent Fines Value]

This ensures uniformity in testing and reliable calculation of fines value as per IS 2386 Part 4.

IS 2386 (Part 4) - Reporting of Results Summary

Key Reporting Requirements (Clause 5.2.7)

• Percentage of wear: Indicates material loss during testing.
• Percentage of crushed fragments: Proportion of crushed particles in the test sample.
• Weight and grading: Weight and particle size distribution of the sample tested.

Aggregate Crushing Value (Clause 2.6)

• Report the mean of two test results as the aggregate crushing value.
• Round off to the nearest whole number.
• Specify the size of the material tested.

Crushing Stress Reporting (Clause 7.6)

• Report crushing stress for each specimen and the average crushing stress.
• Round values to the nearest 5 kg/cm².
• Note any specimen defects (seams, fissures) affecting results.

Formula for Aggregate Crushing Value (ACV):

[ \text{ACV} = \frac{\text{Weight of fines passing 2.36 mm sieve}}{\text{Total weight of sample}} \times 100 ]

Reporting Format Example:

flowchart TD
    A[Sample Preparation] --> B[Conduct Crushing Test]
    B --> C[Measure Weight of Fines]
    C --> D[Calculate % Wear & Crushed Fragments]
    D --> E[Calculate Aggregate Crushing Value (ACV)]
    E --> F[Report Mean of Two Tests (Nearest Whole Number)]
    F --> G[Report Crushing Stress (Nearest 5 kg/cm²)]
    G --> H[Include Remarks on Specimen Condition]

This ensures clarity, accuracy, and compliance with IS 2386 Part 4 for mechanical testing of aggregates.

IS 2386 Part 4: Accelerated Polishing of Specimens (Clauses 6.2, 6.4.2, 6.5, 6.5.1)

Key Specifications:

• Road Wheel:
  • Diameter: 405 mm
  • Width: 45 mm
  • Speed: 320 to 325 rpm
  • Holds 14 specimens clamped around periphery
• Specimens:
  • Size: 90.5 × 44.5 mm
  • Thickness: ≥ 12.5 mm
  • Curvature radius: 400 mm along length
  • Contains 40 to 50 particles embedded in sand-cement mortar
  • Particles exposed surfaces flat, no sharp edges
• Mounting:
  • Use 0.25 mm thick polythene strips between/beneath specimens for spacing
• Polishing Procedure:
  • Initial polishing with sand and water
  • Followed by 3 hours polishing with air-floated emery powder and water feed (rates per clause 6.2a)
  • Clean specimens thoroughly before and after polishing
  • Avoid fingertip contact on polished surfaces

Process Flow:

flowchart TD
    A[Mount 14 specimens on road wheel] --> B[Insert 0.25 mm polythene strips]
    B --> C[Rotate wheel at 320-325 rpm with sand & water]
    C --> D[Clean machine and specimens thoroughly]
    D --> E[Run with air-floated emery powder & water for 3 hours]
    E --> F[Stop and clean specimens]
    F --> G[Test friction as per clause 6.6]

This procedure ensures uniform accelerated polishing simulating wear for friction testing.

IS 2386 Part 4: Measurement of Coefficient of Friction

Key Formula (Clause 6.7)

[ p = \frac{W \times X \times Z \times M}{P \times D} \times 100 ]

Where:

• p = coefficient of friction (%)
• W = weight of swinging arm (kg) = 1.500 ± 0.025
• X = distance from centre of gravity to oscillation centre (cm) = 40.5 ± 0.5
• Z = vertical distance of scale edge below zero (cm) = 1.0 (10 mm)
• M = scale reading (dimensionless)
• P = normal load on slider (kg)
• D = sliding distance (cm)
• p (pointer length) = length of pointer (cm) = 30 cm

Apparatus Specifications (Clause 6.6)

• Pendulum arm length: 50 cm from axis to slider edge
• Slider: spring-loaded rubber, weight & size per RRL UK drawings
• Pointer: max 85 g, 30 cm long, adjustable friction for precise reading
• Test conditions: 20 ± 2 °C

Calibration & Cross-checking (Clause 6.7)

• Test on:
  • Glass plate
  • 5 smooth surfaces (texture depth < 0.25 mm, friction 25–75%)
  • 5 rough surfaces (texture depth > 0.51 mm, friction 35–70%)
• Cross-check with Road Research Laboratory standard machine

Summary Table of Key Parameters

flowchart LR
    A[Pendulum Arm] -->

IS 2386 Part 4: Quality Control & Maintenance of Apparatus

Key Apparatus Specifications (Clause 7.2 & 2.36)

Maintenance & Quality Control Tips

• Calibration: Regularly calibrate balances and compression machines.
• Cleaning: Keep sieves and measures clean and free from rust.
• Inspection: Check tamping rods and cylinders for wear or deformation.
• Oven Temperature: Verify thermostat accuracy frequently.
• Lubrication: Apply light lubrication to moving parts like ratchet counters.

Apparatus Diagram (Simplified)

graph LR
A[Sieves] --> B[Cylindrical Measure]
B --> C[Tamping Rod]
C --> D[Balance]
D --> E[Oven]
E --> F[Compression Machine]

This ensures reliable and repeatable aggregate testing per IS 2386 (Part 4).