Method of Test determination of water-soluble and acid-soluble chlorides in mortar and concrete, Part 1: Fresh mortar and concrete

IS 14959 (Part 1): Scope & Key Specifications

• Scope:
  Covers the volumetric method for determination of water soluble and acid soluble chlorides in fresh mortar and concrete.
  Applicable for samples taken within 2 hours of mixing from project sites or ready-mix plants.

• Sampling:

  • Minimum 3 increments totaling 0.02 m³ of fresh concrete/mortar.
  • Taken at ~1/4, 1/2, and 3/4 discharge from mixer.
  • Use non-absorbent, metal receptacles to avoid segregation.

• Key Formula for Chloride Percentage:
  [ \text{Chloride, %} = 0.00071 \times (X - Y) ] Where:

  • (X) = volume of 0.02 N silver nitrate added (ml)
  • (Y) = volume of 0.02 N ammonium thiocyanate consumed (ml)
  • (m) = mass of concrete sample (g) (used in sample preparation)

• Notes:

  • Nitrobenzene can be added to avoid interference from silver chloride particles during titration.
  • Record exact normality if standard 0.02 N solution is not achievable.

• References:

  • IS 1070:1992 (Reagent grade water)
  • IS 3025 (Part 32):1988 (Chloride test methods)

flowchart LR
  A[Fresh Concrete Sample] --> B[Take 3 increments (total 0.02 m³)]
  B --> C[Mix thoroughly]
  C --> D[Prepare sample for volumetric titration]
  D --> E[Add 0.02N AgNO3 (X ml)]
  E --> F[Titrate with 0.02N NH4SCN (Y ml)]
  F --> G[Calculate % Chloride = 0.00071*(X - Y)]

This standard ensures accurate chloride content measurement critical for durability and corrosion assessment in concrete structures.

IS 14959 (Part 1): Key Formulas and Specifications for Chloride Determination

1. Chloride Percentage Calculation (Clause 4.4)

[ \text{Chloride, %} = \frac{0.00071 (X - Y)}{m} \times 100 ]

Where:

• X = volume of 0.02 N silver nitrate added (ml)
• Y = volume of 0.02 N ammonium thiocyanate consumed (ml)
• m = mass of concrete sample taken for test (g)

Note: Nitrobenzene may be added to avoid interference from silver chloride particles during titration.

2. Sampling Guidelines (Clause 4)

• Collect fresh concrete/mortar samples within 2 hours of water addition.
• Take at least 3 increments, totaling 0.02 m³, uniformly during discharge (at 1/4, 1/2, 3/4 discharge).
• Use a non-absorbent metal container to avoid segregation.

3. References for Related Standards

• IS 1070:1992 — Reagent grade water specifications.
• IS 3025 (Part 32):1988 — Sampling and test methods for chloride in water.

Summary Diagram: Chloride Test Process

flowchart TD
    A[Sample Collection] --> B[Sample Preparation]
    B --> C[Volumetric Titration]
    C --> D[Calculate Chloride % using formula]
    D --> E[Report Results]

This standard ensures accurate determination of water and acid soluble chlorides to assess durability risks in fresh concrete.

IS 14959 Part 1 (2001) - Definitions & Key Formula for Chloride Determination

This part covers the volumetric method for determining water soluble and acid soluble chlorides in fresh mortar and concrete.

Key Definitions:

• Water soluble chlorides: Chlorides extractable in water from concrete.
• Acid soluble chlorides: Chlorides extractable using acid, representing total chlorides.
• Sample: Fresh concrete/mortar taken within 2 hours of mixing, combined from increments totaling 0.02 m³.

Key Formula for Chloride Content (% by mass):

[ \text{Chloride, %} = 0.00071 (X - Y) ]

Where:

• (X) = volume of 0.02 N silver nitrate added (ml)
• (Y) = volume of 0.02 N ammonium thiocyanate consumed (ml)
• (m) = mass of concrete sample (g) (implicitly considered in the constant)

Important Notes:

• Use 0.02 N standard solutions for titrations.
• Nitrobenzene may be added to prevent interference from silver chloride particles.
• Samples should be taken uniformly during discharge at roughly 1/4, 1/2, and 3/4 intervals.

Sampling Guidelines:

• Minimum 3 increments, combined, to avoid segregation.
• Use non-absorbent, preferably metal, containers.

This ensures accurate chloride measurement critical for assessing corrosion risk in reinforced concrete.

flowchart LR
    A[Fresh Concrete/Mortar] --> B[Sample Collection]
    B --> C[Prepare Bulk Sample (0.02 m³)]
    C --> D[Titration with 0.02 N AgNO₃]
    D --> E[Add 0.02 N NH₄SCN]
    E --> F[Calculate Chloride % using formula]

IS 14959 Part 1 (2001) — Method of Test for Chlorides in Fresh Mortar and Concrete

Key Specifications & Formulas:

• Sample Collection:

  • Collect within 2 hours of water addition.
  • Take ≥3 increments totaling 0.02 m³.
  • Use non-absorbent, metal receptacle to avoid segregation.
  • Increments at 1/4, 1/2, and 3/4 discharge times.

• Reagents:

  • Use 0.02 N silver nitrate solution (substituted from 0.2 N).
  • Normality may vary; record exact normality if not exactly 0.02 N.

• Chloride Content Calculation:

[ \text{Chloride, %} = \frac{(X - Y) \times N \times 35.45 \times 100}{m \times 1000} ]

Where:

• (X) = volume of 0.02 N AgNO₃ added (ml)
• (Y) = volume of 0.02 N ammonium thiocyanate consumed (ml)
• (N) = normality of AgNO₃ solution (usually 0.02 N)
• (m) = mass of concrete sample (g)
• 35.45 = atomic weight of chlorine

Notes:

• The formula accounts for titration volumes and sample mass.
• Acid soluble and water soluble chlorides are determined volumetrically.
• Avoid adding 5 ml of 6 N nitric acid (deleted clause).
• Follow IS 2:1960 for rounding off results.

Summary Flow (Sampling & Testing):

flowchart TD
    A[Start: Fresh Concrete Sample] --> B[Collect ≥3 increments (total 0.02 m³)]
    B --> C[Mix increments thoroughly]
    C --> D[Weigh sample (m grams)]
    D --> E[Titrate with 0.02 N AgNO3 (Volume X ml)]
    E --> F[Titrate with 0.02 N NH4SCN (Volume Y ml)]
    F --> G[Calculate Chloride % using formula]
    G --> H[Report results per IS 2:1960 rounding]

This method ensures accurate quantification

IS 14959 Part 1: Reagents and Solutions Key Points

• Quality of Reagents (4.1.1)
  Use analytical reagent grade chemicals and distilled water (per IS 1070).

• Nitric Acid 6N Solution (4.1.2)

  • Dilute 38 ml of concentrated HNO3 (SG 1.42) to 100 ml with distilled water.
  • Approximate normality: 6N.

• Silver Nitrate 0.02 N Solution (4.1.6 & 1.7)

  • Weigh 1.7 g AgNO3, dissolve in distilled water, dilute to 500 ml.
  • Standardize against 0.02 N NaCl using potassium chromate indicator (5% m/v) as per IS 3025 (Part 32).

Summary Table

Standardization Reaction (AgNO3 vs NaCl)

[ \text{AgNO}_3 + \text{NaCl} \rightarrow \text{AgCl (precipitate)} + \text{NaNO}_3 ]

Potassium chromate acts as an indicator to detect endpoint (formation of red silver chromate).

If needed, I can provide a flowchart for preparation and standardization steps.

IS 14959 Part 1: Use of Filter Paper & Chloride Estimation

Key Points from Clauses 4.2, 4.3.1.1, 4.3.1.2, and 4.3.2.2

• Filter Paper:

  • Use Whatman No. 1 filter paper or equivalent porosity for filtering supernatant solution.

• Sample Preparation (Clause 4.3.1.1):

  • Weigh 1000 ± 5 g fresh mortar/concrete.
  • Add 500 ml distilled water (chloride-free).
  • Stir vigorously for 15 minutes, settle for 10-15 minutes.
  • Decant ~200 ml supernatant, filter through Whatman No. 1.

• Titration Procedure (Clauses 4.3.1.2 & 4.3.2.2):

  • Take 50 ml filtrate in conical flask.
  • Add 5 ml 6N HNO₃, X ml standard AgNO₃ (preferably 25 ml).
  • Add 1 ml ferric alum + 5 ml nitrobenzene; shake to coagulate precipitate.
  • Titrate excess AgNO₃ with 0.02 N ammonium thiocyanate until faint reddish-brown endpoint.
  • Record volume of ammonium thiocyanate used = Y ml.

Chloride Content Calculation

[ \text{Chloride} (%) = \frac{(X - Y) \times N \times 35.5 \times 100}{V \times W} ]

Where:

• (X) = volume of AgNO₃ added (ml)
• (Y) = volume of ammonium thiocyanate used (ml)
• (N) = normality of AgNO₃
• (35.5) = atomic weight of chloride
• (V) = volume of filtrate taken for titration (ml) = 50 ml
• (W) = weight of sample (g) = 1000 g

Summary Table

| Parameter | Value/Specification | |----------------------------

IS 14959 Part 1: Procedure for Determination of Chlorides in Fresh Mortar and Concrete

Key Formulas

Chloride Percentage Calculation:

[ \text{Chloride, %} = \frac{(X - Y) \times N \times 35.45 \times V}{m \times 1000} ]

Where:

• (X) = Volume of silver nitrate solution added (ml)
• (Y) = Volume of ammonium thiocyanate consumed (ml)
• (N) = Normality of silver nitrate solution (preferably 0.02 N)
• (V) = Volume of filtrate taken for titration (usually 50 ml)
• (m) = Mass of concrete sample (g)
• 35.45 = Atomic weight of chlorine

Important Specifications & Notes

• Use 0.02 N silver nitrate solution (record exact normality).
• Use 0.02 N ammonium thiocyanate for back titration.
• Add 5 ml of 6 N nitric acid to the filtrate before titration (except where deleted in amendments).
• Add 1 ml ferric alum and 5 ml nitrobenzene to coagulate precipitate.
• Sample size: At least 0.02 m³ combined bulk sample from fresh concrete/mortar.
• Sampling increments: Minimum three, taken at 1/4, 1/2, and 3/4 discharge intervals.
• Titrate until a permanent faint reddish-brown color appears.

Summary Table for Reagents and Volumes

flowchart TD
    A[Sample Collection] --> B[Filtration]
    B --> C[Pipette 50 ml filtrate]
   

IS 14959 Part 1: Water Soluble Chloride Determination - Key Points

Sampling

• Collect fresh concrete/mortar samples within 2 hours of water addition.
• Take at least 3 increments totaling 0.02 m³.
• Use a clean, non-absorbent container (preferably metal).

Volumetric Test Method (Clause 4.3.1)

• Use 0.02 N AgNO₃ (silver nitrate) solution for titration.
• Sample volume: 25 ml or more of extract.
• Titrate to determine volume (X) of AgNO₃ used.

Formula for Chloride Content (%)

[ \text{Chloride, %} = \frac{(X - Y) \times N \times 35.45 \times 100}{m \times 1000} ]

Where:

• (X) = volume of 0.02 N AgNO₃ added (ml)
• (Y) = volume of 0.02 N ammonium thiocyanate consumed (ml)
• (N) = normality of AgNO₃ (usually 0.02 N)
• (m) = mass of concrete sample (g)
• 35.45 = atomic weight of chlorine

Notes

• Normality of AgNO₃ may vary; record exact normality.
• Water soluble chlorides include free chlorides in pore water, critical for corrosion risk.
• Follow IS 2:1960 for rounding off results.

flowchart TD
    A[Sample Collection] --> B[Extract Water Soluble Chlorides]
    B --> C[Titrate with 0.02 N AgNO3]
    C --> D[Record volume X]
    D --> E[Titrate with 0.02 N Ammonium Thiocyanate]
    E --> F[Record volume Y]
    F --> G[Calculate Chloride % using formula]

This method ensures reliable quantification of harmful chlorides in fresh concrete to prevent reinforcement corrosion.

IS 14959 Part 1: Acid Soluble Chloride - Key Formulas & Specifications

1. Definition:
Acid soluble chlorides include both free and combined chlorides bound in the concrete matrix, extracted using acid treatment.

2. Sampling:

• Sample fresh concrete/mortar within 2 hours of mixing.
• Take at least 3 increments totaling 0.02 m³.
• Use non-absorbent containers (preferably metal).

3. Test Procedure Highlights (Clause 4.3.2):

• Use 0.02 N silver nitrate for titration (or record exact normality).
• Acid treatment replaces addition of 5 ml 6N nitric acid (deleted).
• Volume of silver nitrate used is noted for calculation.

4. Chloride Content Calculation (Clause 4.4):

[ \text{Chloride, %} = \frac{(X - Y) \times N \times 35.45 \times 100}{m \times 1000} ]

Where:

• (X) = volume of 0.02 N AgNO₃ added (ml)
• (Y) = volume of 0.02 N ammonium thiocyanate consumed (ml)
• (N) = normality of silver nitrate (usually 0.02 N)
• (m) = mass of concrete sample (g)
• 35.45 = molar mass of chloride ion (g/mol)

5. Notes:

• Ensure titrant normality accuracy; note exact normality if not 0.02 N.
• Follow IS 2:1960 for rounding off results.

flowchart TD
    A[Sample Fresh Concrete] --> B[Take 3 increments (0.02 m³ total)]
    B --> C[Prepare sample for acid extraction]
    C --> D[Titrate with 0.02 N AgNO₃]
    D --> E[Record volume X]
    E --> F[Titrate with 0.02 N ammonium thiocyanate]
    F --> G[Record volume Y]
    G --> H[Calculate % Chloride]

This method ensures accurate determination of acid soluble chloride content critical for durability assessment and corrosion risk evaluation in concrete.

IS 14959 (Part 1) - Key Formula and Specifications for Chloride Calculation

Chloride Content Calculation (Clause 4.4)

Calculate percentage of chloride (acid soluble or water soluble) in mortar or concrete by:

[ \text{Chloride, %} = \frac{0.00071 \times (X - Y) \times 100}{m} ]

Where:

• X = volume of 0.02 N silver nitrate added (ml)
• Y = volume of 0.02 N ammonium thiocyanate consumed (ml)
• m = mass of concrete sample taken for test (g)

Note: Nitrobenzene can be added to avoid interference from silver chloride particles during titration.

Sampling and Testing Procedure Highlights:

• Sample size: 1000 ± 5 g fresh mortar/concrete.
• Extract with 500 ml distilled water, stir 15 min.
• Decant and filter supernatant (~200 ml) for titration.
• Use volumetric titration with 0.02 N silver nitrate and ammonium thiocyanate.

Important Notes:

• Chlorides cause corrosion in reinforced concrete; hence, their quantification is crucial.
• Water soluble and acid soluble chlorides are tested separately.
• Sampling must be representative: at least 3 increments totaling 0.02 m³.

flowchart TD
    A[Fresh Concrete Sample] --> B[Weigh 1000g ±5g]
    B --> C[Add 500 ml Distilled Water]
    C --> D[Stir 15 min]
    D --> E[Settle 10-15 min]
    E --> F[Decant 200 ml Supernatant]
    F --> G[Filter Solution]
    G --> H[Titrate with 0.02 N AgNO3 (X ml)]
    H --> I[Titrate with 0.02 N NH4SCN (Y ml)]
    I --> J[Calculate Chloride %]

This formula and procedure ensure accurate chloride determination per IS 14959 (Part 1): 2001.

IS 14959 Part 1: Reporting of Results for Chloride Determination

Key Formula for Chloride Content (%)

[ \text{Chloride, %} = \frac{(X - Y) \times N \times 35.45 \times 100}{m \times 1000} ]

Where:

• X = volume of 0.02 N silver nitrate added (ml)
• Y = volume of 0.02 N ammonium thiocyanate consumed (ml)
• N = normality of silver nitrate (usually 0.02 N)
• m = mass of concrete sample (g)
• 35.45 = atomic weight of chlorine

Key Specifications & Notes:

• Use 0.02 N silver nitrate and ammonium thiocyanate solutions.
• Record exact normality of silver nitrate solution used.
• Sample size: minimum 25 ml or more of solution for titration.
• Add 5 ml of 6 N nitric acid to filtrate before titration (except clause 4.3.2.2 deletion noted).
• Rounding off results as per IS 2:1960 rules.
• Use analytical reagent grade chemicals and distilled water (IS 1070).

Sampling:

• Collect at least 3 increments totaling 0.02 m³ of fresh concrete/mortar.
• Samples should be taken at approx. 1/4, 1/2, and 3/4 discharge times.

flowchart LR
    A[Sample Collection] --> B[Mix & Prepare Filtrate]
    B --> C[Add 5 ml 6N HNO3]
    C --> D[Add X ml 0.02N AgNO3]
    D --> E[Add 1 ml Ferric Alum + 5 ml Nitrobenzene]
    E --> F[Titrate excess AgNO3 with 0.02N NH4SCN]
    F --> G[Calculate Chloride % using formula]

This summarizes the key points for reporting chloride test results per IS 14959 Part 1.

Committee Composition - IS 14959 Part 1 (Annex A)

The Cement and Concrete Sectional Committee, CED 2 formulated this standard. Key members represent:

• Industry & Research Institutes: OCL India Ltd, Geological Survey of India, Structural Engineering Research Centre (CSIR), Indian Institute of Technology Kharagpur, National Council for Cement and Building Materials.
• Government Departments: Central Public Works Department, Ministry of Surface Transport, Central Water Commission, Directorate General of Supplies and Disposals.
• Construction & Cement Companies: B.G. Shirke Construction Technology Ltd, Hindustan Prefab Ltd, Gujarat Ambuja Cements Ltd, The India Cements Ltd, Grasim Industries Ltd, Cement Corporation of India Ltd.
• Others: National Test House, Builder's Association of India, Fly Ash Mission, Research, Designs & Standards Organization (Ministry of Railways).

Key Specification for Committee Composition

• Includes Chairman, Members, Alternates, and Member-Secretary.
• Members are drawn from diverse sectors ensuring broad expertise in cement, concrete technology, construction, and standards.
• The committee is responsible for drafting, reviewing, and approving the standard.

Summary Table of Committee Composition

This composition ensures multidisciplinary inputs for robust standard development in chloride determination in concrete.

If you need formulas or test methods from the code, please specify!