IS.2386.2.1963

Simplified Guide to IS 2386 (Part II) - 1963: Methods of Test for Aggregates for Concrete - Part II: Estimation of Deleterious Materials and Organic Impurities

This guide explains IS 2386 (Part II) - 1963, the Indian Standard for testing aggregates for concrete, focusing on deleterious materials and organic impurities, in a clear and concise manner for students and engineers. It includes examples, procedures, and references to clarify the test methods. Due to OCR errors and truncated sections in the provided document, this guide uses reliable information and standard industry knowledge to address gaps.

Why This Standard Matters

IS 2386 (Part II) - 1963, adopted by the Bureau of Indian Standards (BIS) on 22 August 1963 (reaffirmed 2011, with an amendment in February 1983), specifies test methods for assessing deleterious materials and organic impurities in aggregates used in concrete. These materials, such as clay, silt, coal, lignite, soft particles, and organic impurities, can adversely affect concrete’s strength, durability, and workability, making this standard critical for construction projects like buildings, roads, and dams.

Key Benefit: The standard provides standardized procedures to ensure aggregates are free from harmful substances, ensuring high-quality concrete production. It aligns with international standards (e.g., British Standards Institution, American Society for Testing and Materials) and local practices.

References: [IS 2386 (Part II) - 1963, Foreword, Page 8; Clause 1, Page 9]

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Key Sections Explained

1. Scope: What’s This About?

This standard covers five test methods for aggregates used in concrete:

• Determination of Clay Lumps: Measures the percentage of clay lumps that can be broken down by hand.
• Determination of Clay, Fine Silt, and Fine Dust (Sedimentation Method): Quantifies fine particles (up to 20 microns) using a gravimetric sedimentation method.
• Determination of Light-Weight Pieces (Coal and Lignite): Assesses the percentage of coal and lignite using sink-float separation.
• Determination of Soft Particles: Identifies soft particles in coarse aggregates based on scratch-hardness.
• Estimation of Organic Impurities: Checks for harmful organic compounds in fine aggregates by color comparison.

Example for Students: These tests are like checking for unwanted ingredients in a recipe that could ruin the concrete mix.
Example for Engineers: Use these tests to ensure aggregates for a high-rise building foundation meet IS 383:2016 limits for deleterious materials (e.g., ≤1% clay lumps for fine aggregates).

Reference: [IS 2386 (Part II) - 1963, Clause 1.1, Page 9]

2. Foreword: Context and Purpose

The standard, developed by the Cement and Concrete Sectional Committee (BDC 2), emphasizes the importance of aggregate quality in concrete performance. It is part of an eight-part series (IS 2386:1963) covering various aggregate tests (e.g., particle size, specific gravity, soundness). The tests in Part II help identify deleterious materials and organic impurities that could compromise concrete quality.

Key Features:

• Aligns with international standards (e.g., BSI, ASTM).
• References the latest versions of Indian Standards (e.g., IS 460-1962 for test sieves).
• Numerical values are rounded per IS 2:1960.
• Focuses on technical provisions, not contractual details.

Example: The standard ensures aggregates for a dam project are free from clay or coal, preventing issues like reduced strength or staining.

Reference: [IS 2386 (Part II) - 1963, Foreword, Pages 8–9]

3. Determination of Clay Lumps (Clause 2)

Object: Determines the approximate percentage of clay lumps in aggregates, as these can weaken concrete by absorbing water or disintegrating.

Apparatus:

• Balance: Accurate to 0.1% of sample weight.
• Containers: For spreading samples in a thin layer.
• Sieves: Per IS 460-1962 (e.g., 1.18-mm, 4.75-mm).

Sample:

• Fine Aggregate: Particles coarser than 1.18-mm IS Sieve, minimum 100 g.
• Coarse Aggregate: Separated into sizes (4.75–10 mm: 1000 g; 10–20 mm: 2000 g; 20–40 mm: 3000 g; >40 mm: 5000 g).
• Dry to constant weight at ≤110°C.
• Prepare by quartering or using a sampler, avoiding breaking clay lumps.

Procedure:

1. Spread the sample in a thin layer in a container.
2. Identify and break clay lumps (particles that crumble into fine particles with finger pressure).
3. Sieve residue through specified sieves (e.g., 850-micron for fine aggregate, 4.75-mm for coarse aggregate >20 mm).
4. Calculate percentage of clay lumps:
   [
   L = \frac{W - R}{W} \times 100
   ]
   where ( L ) = percentage of clay lumps, ( W ) = original sample weight, ( R ) = weight after removing clay lumps.

Reporting: Report to the nearest 0.1%.

Example for Students: Clay lumps are like clumps of mud in sand that need to be removed to keep concrete strong.
Example for Engineers: Ensure fine aggregate for a pavement has ≤1% clay lumps (per IS 383:2016, Table 2) to avoid water absorption issues.

References: [IS 2386 (Part II) - 1963, Clauses 2.1–2.6, Pages 9–11]

4. Determination of Clay, Fine Silt, and Fine Dust (Sedimentation Method) (Clause 3)

Object: Measures the content of clay, fine silt, and fine dust (up to 20 microns) in aggregates, as these increase water demand and reduce concrete strength.

Apparatus:

• Glass Jar: 1-kg fruit-preserving jar, watertight, screw-topped.
• Rotating Device: Rotates jar at 80 ± 20 rpm.
• Sedimentation Pipette: Andreason type, ~25 ml capacity (Fig. 1).
• Measuring Cylinder: 1000-ml.
• Balances: 10 kg (accurate to 1 g), 250 g (accurate to 0.001 g).
• Oven: 100–110°C.

Chemicals: 8 g/L sodium oxalate solution, diluted to 0.8 g/L for testing.

Sample:

• Minimum weights (Table I):
  • 63–25 mm: 6 kg
  • 20–12.5 mm: 1 kg
  • 10–6.3 mm: 0.5 kg
  • ≤4.75 mm: 0.3 kg
• Separate all-in aggregates into fine and coarse fractions using a 4.75-mm IS Sieve.

Procedure:

1. Fine Aggregate:
   • Weigh 300 g (air-dry, passing 4.75-mm sieve).
   • Place in jar with 300 ml diluted sodium oxalate solution.
   • Rotate at 80 ± 20 rpm for 15 minutes.
   • Pour suspension into a 1000-ml cylinder, wash residue with 150-ml portions of solution until the volume reaches 1000 ml.
2. Coarse Aggregate:
   • Place sample in a container, cover with 0.8 g/L sodium oxalate solution, agitate to remove fine material, and transfer suspension to a 1000-ml cylinder.
   • Repeat until all clayey material is transferred, make up to 1000 ml.
3. Sedimentation:
   • Mix suspension in the cylinder by inversion.
   • Lower pipette 10 cm into the liquid 3 minutes after mixing.
   • Draw a sample into the pipette, transfer to a weighed container, wash with distilled water, dry at 100–110°C, and weigh.
4. Calculate percentage of clay, fine silt, and fine dust:
   [
   \text{Percentage} = \frac{100}{W_1} \left( \frac{1000 W_2}{V} - 0.8 \right)
   ]
   where ( W_1 ) = original sample weight (g), ( W_2 ) = dried residue weight (g), ( V ) = pipette volume (ml), 0.8 = sodium oxalate weight in 1 L solution.

Reporting: Report to the nearest 0.1%.

Example for Students: This test is like filtering out tiny dirt particles from sand to ensure clean concrete.
Example for Engineers: Ensure fine aggregate for a bridge has ≤3% fine silt and dust (per IS 383:2016, Table 2) to maintain workability.

References: [IS 2386 (Part II) - 1963, Clauses 3.1–3.7, Pages 11–15]

5. Determination of Light-Weight Pieces (Coal and Lignite) (Clause 4)

Object: Determines the percentage of light-weight pieces (coal and lignite) in aggregates, as these reduce concrete strength and cause staining.

Apparatus:

• Balances: 500 g (0.1 g accuracy) for fine aggregates, 5000 g (1 g accuracy) for coarse aggregates.
• Containers: For drying and holding heavy liquid.
• Skimmer: 300-micron sieve cloth.
• Hot-Plate or Oven.

Heavy Liquid:

• Mixture of carbon tetrachloride, 1,1,2,2-tetrabromoethane, bromoform, monobromobenzene, or bromoform-benzene, adjusted to a specific gravity of 2.00 ± 0.01.
• Specific gravities: Tetrabromoethane (2.97), bromoform (2.88), carbon tetrachloride (1.58), monobromobenzene (1.49), benzene (0.88).
• Caution: These chemicals are toxic; use in a hood, avoid skin contact and inhalation.

Sample:

• Minimum weights:
  • 6.3 mm (fine): 200 g
  • 20 mm: 3000 g
  • 40 mm: 5000 g
  • 80 mm: 10000 g

Procedure:

1. Fine Aggregate:
   • Dry and cool the sample, sieve over a 300-micron IS Sieve.
   • Weigh material coarser than 300-micron.
   • Place in heavy liquid (volume ≥3 times aggregate volume), decant floating pieces onto skimmer.
   • Repeat agitation and decanting until no pieces float.
   • Wash decanted pieces with carbon tetrachloride, dry, and weigh to 0.1 g.
2. Coarse Aggregate:
   • Dry and cool, sieve over a 4.75-mm IS Sieve.
   • Weigh material coarser than 4.75-mm.
   • Place in heavy liquid, remove floating pieces with skimmer, repeat until no pieces float.
   • Wash, dry, and weigh decanted pieces to 1 g.
3. Calculate percentage of light-weight pieces:
   • Fine aggregate: ( L = \frac{W_1}{W_2} \times 100 )
   • Coarse aggregate: ( L = \frac{W_1}{W_3} \times 100 )
     where ( W_1 ) = weight of decanted pieces, ( W_2 ) = weight coarser than 300-micron, ( W_3 ) = weight coarser than 4.75-mm.

Reporting: Report to the nearest 0.1%.

Example for Students: Coal and lignite float because they’re lighter than sand or gravel, and this test removes them to keep concrete strong.
Example for Engineers: Ensure coarse aggregate for a dam has ≤0.5% coal and lignite (per IS 383:2016, Table 2) to avoid staining and strength loss.

References: [IS 2386 (Part II) - 1963, Clauses 4.1–4.7, Pages 15–17]

6. Determination of Soft Particles (Clause 5)

Object: Identifies soft particles in coarse aggregates (≥10 mm) by scratch-hardness, as these can reduce concrete durability.

Apparatus: Brass rod (1.6 mm diameter, Rockwell hardness 65–75 RHB), often inserted into a pencil for ease of use.

Sample:

• Remove particles <10-mm IS Sieve.
• Minimum weights for sizes (≥10% of sample):
  • 10–12.5 mm: 200 g
  • 12.5–20 mm: 600 g
  • 20–25 mm: 1500 g
  • 25–40 mm: 4500 g
  • 40–50 mm: 12000 g
• If a size has <10% material, assume it has the same soft particle percentage as the average of adjacent sizes.

Procedure:

1. Scratch each particle with the brass rod using ~1 kg pressure.
2. Classify particles as soft if a groove is made without brass deposition or if particles detach from the mass.
3. Record weight and number of soft and total particles per size fraction.

Reporting:

• Weight and number of particles tested and classified as soft per size.
• Percentage of soft particles by weight and number.
• Weighted average percentage based on sample grading (exclude <10-mm sizes).

Example for Students: Soft particles are like weak rocks that crumble easily, making concrete less durable.
Example for Engineers: For a bridge pier, ensure soft particles are minimal (e.g., ≤1%) to maintain structural integrity.

Reference: [IS 2386 (Part II) - 1963, Clauses 5.1–5.5, Pages 18–19]

7. Estimation of Organic Impurities (Clause 6, Amended 1983)

Object: Approximates the presence of harmful organic compounds in natural sand by color comparison, indicating if further tests (e.g., IS 2386 Part VI) are needed.

Procedure:

1. Fill a 350-ml clear glass medicine bottle to 75 ml with 3% sodium hydroxide (NaOH) solution.
2. Add undried sand until the sand layer reaches 125 ml.
3. Add more NaOH solution to reach 200 ml.
4. Stopper, shake vigorously, and let stand for 24 hours.
5. Compare the color of the liquid above the sand to a standard solution:
   • Prepare standard: Mix 2.5 ml of 2% tannic acid (in 10% alcohol) with 97.5 ml of 3% NaOH solution, shake, and let stand for 24 hours.
   • If the sample liquid is darker than the standard, further tests are required (e.g., mortar strength test per IS 2386 Part VI).
   • Alternatively, use a color comparison instrument or verified acetate sheets.

Note: Harmless organic materials may cause coloration, and some harmful ones may not.

Example for Students: This test is like checking if sand has invisible “dirt” that could harm concrete by seeing if the water turns too dark.
Example for Engineers: If the test shows a dark color, conduct further tests to confirm organic impurities are below harmful levels (per IS 383:2016).

References: [IS 2386 (Part II) - 1963, Clauses 6.1–6.2, Pages 19–20; Amendment 1, Page 7]

8. Committee Composition (Pages 5–6)

The Cement and Concrete Sectional Committee (BDC 2) included experts from:

• The Concrete Association of India, M.N. Dastur & Co., Bhakra Dam Designs Directorate, ACC Ltd., Gammon India Ltd., and others.

Example: The committee’s expertise ensures practical and reliable test methods for real-world applications.

Reference: [IS 2386 (Part II) - 1963, Pages 5–6]

9. Amendment (Page 7)

• Amendment No. 1 (1983): Revised Clause 6.1 to clarify that the organic impurities test is approximate and indicates the need for further tests (e.g., IS 2386 Part VI). Added notes on harmless coloration and non-coloring organic compounds.

Example for Engineers: Check the amendment to ensure proper interpretation of organic impurities test results.

Reference: [IS 2386 (Part II) - 1963, Page 7]

10. Copyright

BIS holds the copyright, so reproduction requires permission. Test methods can be implemented without restriction.

Reference: [IS 2386 (Part II) - 1963, Page 3]

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Practical Tips for Students and Engineers

• Why Use IS 2386 (Part II)?: Ensures aggregates are free from harmful materials like clay, silt, coal, lignite, soft particles, and organic impurities, improving concrete quality.
• Key Steps for Testing:
  1. Conduct clay lumps test to ensure ≤1% for fine aggregates and ≤2% for coarse aggregates (per IS 383:2016, Table 2).
  2. Use sedimentation method to verify fine silt and dust ≤3% for fine aggregates (per IS 383:2016, Table 2).
  3. Check coal and lignite content (≤0.5% for critical structures) to prevent staining and strength loss.
  4. Test for soft particles in coarse aggregates to ensure durability (e.g., ≤1% for high-strength concrete).
  5. Perform organic impurities test to screen fine aggregates; if the color is dark, conduct further strength tests.
• Safety Note: Handle toxic heavy liquids (e.g., bromoform) with care, using a hood and avoiding skin contact or inhalation.
• Quality Control: Use precise equipment (e.g., accurate balances, standard sieves) and follow procedures to avoid errors like sample contamination.
• Integration with IS 383:2016: Cross-reference test results with IS 383:2016 limits (e.g., Table 2 for deleterious materials) for compliance.
• Practical Example:
  • Students: Perform the clay lumps test in a lab to check if sand is clean enough for concrete.
  • Engineers: Test aggregates for a high-rise building to ensure coal and lignite content is ≤0.5% and organic impurities do not require further testing.

References: [IS 2386 (Part II) - 1963, Clauses 2–6, Pages 9–20; IS 383:2016, Table 2]

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Why This Matters

For students, IS 2386 (Part II) - 1963 provides practical methods to understand how deleterious materials affect concrete quality. For engineers, it offers standardized procedures to ensure aggregates meet project specifications, ensuring safe and durable structures. These tests are essential for quality control in construction.