Methods of test for chemical resistant mortars, Part II: Sulphur type

IS 4456 Part 2 - Scope Summary

Scope (Clause 1.1):
This standard specifies test methods for sulphur type chemical resistant mortar, covering:

Key Notes:

• Rounding off numerical values follows IS: 2-1960.
• Chemical resistance tests refer to IS 4456 Part I for detailed procedures.
• The standard aligns with international practices for chemical resistant mortars.

Quick Reference Table: Test Methods Overview

If you need formulas or detailed test procedures, please specify which test method you want to explore.

IS 4456 Part 2: Preparation and Conditioning of Test Specimens

Key Specifications for Conditioning Test Specimens:

• Removal from Mould: Specimens should be removed as soon as the mortar has solidified.
• Conditioning Duration: Age specimens for 48 hours in air.
• Temperature: Maintain at 27°C ± 2°C during conditioning.
• Inclusion of Mould Time: The 48 hours includes the time specimens remain in the mould.

Summary Table:

Notes:

• Conditioning ensures uniform curing before testing.
• The temperature and time control hydration and strength development.

flowchart TD
    A[Moulding of Specimen] --> B[Specimen solidifies]
    B --> C[Remove from mould]
    C --> D[Condition in air at 27°C ± 2°C]
    D --> E[Total conditioning time = 48 hours (including mould time)]
    E --> F[Ready for testing]

This process ensures consistent and reliable test results as per IS 4456 Part 2.

IS 4456 Part 2: Compressive Strength Test - Key Points

1. Calculation of Compressive Strength (Clause 2.7)

[ \text{Compressive Strength} = \frac{\text{Maximum Crushing Load (kg)}}{\text{Average Area (cm}^2\text{)}} ]

• Use the average cross-sectional area of the cube face in contact.
• Discard any manifestly faulty cubes.
• If any specimen's strength differs by more than 15% from the average or if fewer than 4 specimens are tested, repeat the test.

2. Testing Procedure (Clause 2.6)

• Test cubes on their sides without packing.
• Place the cube faces that were in contact with the mould surfaces against the steel platens.
• Load is applied steadily at a rate of 200 kg/cm²/min.
• Record the maximum load at failure.

3. Reporting (Clause 2.8)

• Report the average compressive strength in kg/cm².

Summary Table

flowchart TD
    A[Prepare Cubes] --> B[Test on Side]
    B --> C[Load Applied @ 200 kg/cm²/min]
    C --> D[Record Max Load]
    D --> E[Calculate Strength = Load / Area]
    E --> F{Strength Variation > 15%?}
    F -- Yes --> G[Repeat Test]
    F -- No --> H[Report Average Strength]

This ensures reliable and standardized compressive strength measurement as per IS 4456 Part 2.

IS 4456 Part 2: Tensile Strength Test Key Points

• Number of Tests:
  Six tensile strength test results are taken (Clause 3.8).

• Data Treatment:

  • Calculate the average tensile strength from all six tests.
  • Discard any test result differing by more than 15% from the average (Clause 3.7.2).
  • If fewer than four results remain after discarding, repeat the test.

• Reporting:
  Report the average tensile strength in kg/cm² (Clause 3.8).

Summary Table for Tensile Strength Calculation

Formula for Average Tensile Strength (after discarding outliers):

[ f_t = \frac{\sum_{i=1}^n f_{t,i}}{n} ]

Where:

• (f_{t,i}) = individual tensile strength values (after discarding outliers)
• (n \geq 4) = number of valid test results

If needed, tensile strength is typically calculated from the maximum load (P) divided by the cross-sectional area (A):

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

flowchart TD
    A[Start: 6 Test Results] --> B[Calculate Average]
    B --> C{Any result >15% deviation?}
    C -- Yes --> D[Discard Outliers]
    C -- No --> E[Calculate Average of all 6]
    D --> F{Valid results ≥ 4?}
    F -- Yes --> G[Calculate Average of Remaining]
    F -- No --> H[Repeat Test]
    E --> I[Report Average Tensile Strength (kg/cm²)]
    G --> I

Note: Use a calibrated compression testing machine as per Clause 2.2.3 for specimen loading.

IS 4456 Part 2: Flexural Strength Test Key Points

1. Flexural Strength Reporting

• Report the average tensile strength from six test results (Clause 3.8).
• Discard any strength values differing by more than 15% from the average (Clause 3.7.2).
• If fewer than four values remain after discarding, repeat the test.

2. Calculation of Strength Retention (After Thermal Shock)

[ C = \frac{B}{A} \times 100 ] Where:

• (A) = Average tensile strength before thermal shock (kg/cm²)
• (B) = Average tensile strength after thermal shock (kg/cm²)
• (C) = Percentage of original strength retained (%) (Clause 6.4)

3. Average Compressive Strength

• Report average compressive strength in kg/cm² (Clause 2.8).

Summary Table

Notes:

• Use apparatus as per Fig. 1 for mortar joint preparation.
• Follow Part I for chemical resistant mortar test methods.

flowchart TD
    A[Test 6 specimens] --> B[Calculate average tensile strength]
    B --> C{Any value >15% deviation?}
    C -- Yes --> D[Discard outliers]
    C -- No --> E[Report average]
    D --> F{Less than 4 values left?}
    F -- Yes --> G[Repeat test]
    F -- No --> E

This ensures reliable flexural strength data per IS 4456 Part 2.

IS 4456 Part 2 - Thermal Shock Resistance

Key Formula (Clause 6.4)

Calculate percentage strength retention (C) after thermal shock as:

[ C = \frac{B}{A} \times 100 ]

• A = Average tensile strength before thermal shock (kg/cm²)
• B = Average tensile strength after thermal shock (kg/cm²)
• C = Percent strength retained (%)

Test Procedure Summary (Clauses 6.1, 6.5)

• Prepare mortar joints as per Fig.1 (casting method).
• Subject specimens to thermal shock cycles.
• Measure tensile strength before and after treatment.
• Report C as the key indicator of thermal shock resistance.

Additional Notes

• Mortar should be melted and cast as per Clause 5.1.
• Allow 15 minutes for setting before handling.
• Thermal shock resistance is critical for sulphur mortars used in chemically resistant applications.

flowchart LR
    A[Prepare mortar joint] --> B[Measure tensile strength before shock (A)]
    B --> C[Thermal shock treatment]
    C --> D[Measure tensile strength after shock (B)]
    D --> E[Calculate % retention (C = B/A × 100)]
    E --> F[Report thermal shock resistance]

This formula and procedure ensure durability assessment of sulphur mortars under thermal cycling.

IS 4456 Part 2: Moisture Absorption Test Key Points

1. Objective (Clause 7.1)

• Determine the percentage moisture absorption of sulphur type chemical resistant mortars.

2. Test Procedure (Clause 7.5)

• Submerge specimens in water at 85°C for 5 hours.
• Weigh specimens before (dry weight, W1) and after submersion (saturated weight, W2).

3. Calculation Formula (Clause 7.5)

[ \text{Percentage Absorption} = \frac{W_2 - W_1}{W_1} \times 100 ]

• W1 = dry weight of specimen
• W2 = saturated weight after immersion

4. Reporting (Clause 7.6)

• Report the average percentage moisture absorption of all specimens tested.

Summary Table:

flowchart TD
    A[Dry Specimen] -->|Weigh W1| B[Record Dry Weight]
    B --> C[Submerge in Water at 85°C for 5 hrs]
    C --> D[Remove & Weigh Saturated Specimen W2]
    D --> E[Calculate % Absorption = ((W2 - W1)/W1)*100]
    E --> F[Report Average % Moisture Absorption]

This test ensures the mortar's resistance to moisture ingress, critical for chemical resistance performance.

IS 4456 Part 2 (1967) – Determination of Sulphur Content

Key Specifications & Procedure (Clauses 8.1, 8.3, 8.3.1)

• Sample: 10-15 g of mortar specimen placed in a pre-weighed Whatman filter thimble.
• Solvent: 40-50 ml Carbon Disulphide (CS₂), toxic & flash point 4°C (handle with care).
• Extraction:
  • Suspend thimble under condenser (Fig. 2 apparatus).
  • Heat gently in water bath to vaporize CS₂.
  • Circulate cold water in condenser.
  • Continue extraction until CS₂ fills thimble and siphons over 20 times.
  • Wash filter with CS₂ until no residue remains on evaporation.
• Drying:
  • Dry filter first at low temperature to avoid ignition.
  • Then at 100°C to constant weight.
• Calculation:
  • Sulphur content (%) = Loss in weight of filter after extraction / Weight of specimen × 100

Apparatus (Fig. 2 Highlights)

• 8 mm block-tin tubing
• Nickel or tin-plated metal parts
• Heat-resistant glass flask
• Filter paper/thimble pre-extracted with acetone & chloroform

Summary Formula:

[ \text{Sulphur Content (%)} = \frac{W_1 - W_2}{W_s} \times 100 ]

Where:

• ( W_1 ) = Weight of filter + specimen before extraction (g)
• ( W_2 ) = Weight of filter after extraction & drying (g)
• ( W_s ) = Weight of specimen (g)

Safety Note:

• Carbon disulphide is highly flammable and toxic; ensure good ventilation and avoid ignition sources.

flowchart LR
    A[Specimen in Filter Thimble] --> B[Add Carbon Disulphide]
    B --> C[Heat in Water Bath]
    C --> D[Condensation & Reflux]
    D --> E[Extraction Complete?]
    E -- No --> C
    E -- Yes --> F[Remove Filter]
    F --> G[Dry at Low Temp]
    G --> H[

Aggregate Settlement Evaluation (IS 4456 Part 2)

Key Procedure (Clause 9.3)

• Fill glass tube with molten sulphur mortar at 140℃ for 30 min.
• Cool first in warm water until congealing begins, then immerse in ice water to solidify.
• Break tube; extract top and bottom thirds separately.
• Determine sulphur and aggregate content in each portion (per Clause 8.3).

Settlement Index Calculation

[ \text{Settlement Index} = \frac{\text{Aggregate content (bottom portion)}}{\text{Aggregate content (top portion)}} ]

• Index > 1: Aggregate tends to settle (e.g., coarse silica).
• Index < 1: Aggregate tends to float (e.g., coke aggregate).

Reporting (Clauses 8.4 & 9.4)

• Report percentage sulphur content of the mortar.
• Report the settlement index indicating aggregate settling tendency.

Summary Table

flowchart TD
    A[Fill tube with molten sulphur mortar] --> B[Hold at 140℃ for 30 min]
    B --> C[Cool in warm water until congealed]
    C --> D[Immerse in ice water to solidify]
    D --> E[Break tube; extract top & bottom thirds]
    E --> F[Measure aggregate content in each]
    F --> G[Calculate Settlement Index = Bottom/Top]
    G --> H{Index > 1?}
    H -- Yes --> I[Aggregate tends to settle]
    H -- No --> J[Aggregate tends to float]

This method quantifies aggregate segregation in sulphur mortar, critical for ensuring uniformity and durability in sulphur concrete applications.

IS 4456 Part 2 – Chemical Resistance Testing: Key Points

Testing Procedure (Clause 10.4)

• Testing follows methods in Clauses 10.8 to 10.12 of IS 4456 Part I (1967).
• These clauses detail procedures for chemical resistance tests on silicate and resin-type mortars.
• Tests assess mortar's durability against aggressive chemicals by immersion or exposure to chemical solutions for specified durations.

Key Specifications:

• Test Duration: Typically ranges from 7 to 28 days or as specified.
• Chemical Solutions: Acids, alkalis, salts, or other aggressive agents per test requirements.
• Parameters Measured:
  • Weight loss (%)
  • Visual changes (color, texture)
  • Compressive strength reduction

Reporting (Clause 9.4)

• Report the settling index indicating aggregate's tendency to settle during testing.
• Provide detailed observations on chemical attack and resistance.

Reference Standard:

• ASTM C267-1965 can be used as a complementary guide for chemical resistance testing of mortars.

Summary Table (Example)

For detailed procedures, refer to IS 4456 Part I (Clauses 10.8–10.12) and ASTM C267.

flowchart TD
    A[Prepare Mortar Sample] --> B[Immerse in Chemical Solution]
    B --> C[Maintain for Specified Duration]
    C --> D[Measure Weight Loss & Strength]
    D --> E[Visual Inspection]
    E --> F[Report Settling Index & Results]

Note: Contact nearest BIS regional office for official copies or clarifications.

IS 4456 Part 2: Calculation and Reporting of Results

Key Points from the Code:

• Rounding Off (Clause 0.4):
  Final values (observed or calculated) must be rounded as per IS 2-1960 (Rules for rounding off numerical values).

• Reporting Compressive Strength (Clause 2.8):

  • Report the average compressive strength in kg/cm².

• Reporting Tensile Strength (Clause 9.4):

  • Report the index indicating the aggregate's tendency to settle (settling index).

Additional Notes (General Practice):

• Average Compressive Strength Calculation:
  [ f_c = \frac{\sum f_i}{n} ] where ( f_i ) = individual compressive strength values, ( n ) = number of specimens.

• Rounding Off (IS 2-1960):

  • If the digit to be dropped is <5, round down.
  • If >5, round up.
  • If =5, round to the nearest even number.

Summary Table:

flowchart TD
    A[Test/Analysis] --> B[Calculate Values]
    B --> C{Round Off as per IS 2-1960?}
    C -->|Yes| D[Round Values]
    D --> E[Report Values]
    C -->|No| E
    E --> F[Report avg. compressive strength (kg/cm²)]
    E --> G[Report settling index (if applicable)]

This ensures standardized, clear, and consistent reporting of test results as per IS 4456 Part 2.

IS 4456 Part 2: Apparatus and Equipment - Key Specifications & Procedure

1. Extraction Apparatus (Clause 8.2 & Fig. 2)

• Components:
  • Heat-resistant glass flask
  • 8 mm block-tin tubing (nickel or tin plated metal)
  • Filter paper/thimble (pre-extracted with acetone and chloroform)
  • Condenser with cold water circulation
• Dimensions:
  • Glass tube: Heat resistant, 25 mm diameter × 200 mm length (Clause 9.2.1)
• Operation:
  • Place 10-15 g specimen in filter thimble
  • Pour 40-50 ml carbon disulphide over specimen
  • Suspend thimble under condenser
  • Heat flask in water bath to vaporize solvent; solvent condenses and extracts specimen repeatedly
  • Extraction continues until solvent has siphoned over 20 times and no residue remains after evaporation (Clause 8.3)

2. Chemical Resistance Testing (Clause 10.4 & Table 10)

• Testing follows methods in IS 4456 Part I (1967), Clauses 10.8 to 10.12
• Applicable for silicate and resin type chemical resistant mortars

Summary Table: Extraction Apparatus Dimensions

flowchart TD
    A[Specimen in Filter Thimble] --> B[Placed in Extraction Flask]
    B --> C[Add Carbon Disulphide (40-50 ml)]
    C --> D[Heat Flask in Water Bath]
    D --> E[Solvent Vaporizes & Condenses]
    E --> F[Solvent Extracts Specimen Repeatedly]
    F --> G[Collect Extracted Solvent]
    G --> H[Evaporate to Check Residue]
    H -->|Residue Present| B
    H -->|No Residue| I[Extraction Complete]

For detailed chemical resistance test procedures, refer to IS 4456

IS 4456 Part 2: Safety and Handling Precautions Summary

The code primarily references chemical resistance testing methods (IS 4456 Part I) and highlights safety notes related to chemical handling:

Key Safety Points:

• Handling Toxic Chemicals:
  • Carbondisulphide is toxic with a low flash point (4ºC).
  • Dry samples carefully at low temperatures to avoid ignition.
• Testing Precautions:
  • Follow test methods in clauses 10.8 to 10.12 (Part I) strictly to ensure safe handling of chemical resistant mortars.
• Reporting:
  • Report the aggregate settlement index as per Clause 9.4.

Important Specifications:

Contact for Clarifications:

• Regional and branch offices of Bureau of Indian Standards (BIS) are listed for technical support.

Summary Diagram: Chemical Handling Safety Flow

flowchart TD
    A[Start Testing] --> B[Remove Filter]
    B --> C[Dry at Low Temp]
    C --> D{Is Temp < Flash Point?}
    D -- Yes --> E[Dry at 100ºC to Constant Weight]
    D -- No --> F[Risk of Ignition - Stop Process]
    E --> G[Weigh Residue]
    G --> H[Report Results]

For detailed chemical resistance test methods and safety, refer to IS 4456 Part I clauses 10.8 to 10.12.