Methods of Test for Chemical Resistant Mortars, Part I: Silicate Type and Resin Type

IS 4456 Part 1 - Scope & Key Specifications

This standard specifies test methods for silicate and resin type chemical resistant mortars covering:

Key Notes:

• Test Specimens and preparation details are in Clause 10.5.
• Calculations for test results are given in Clause 10.10.
• Numerical values should be rounded as per rules in Clause 18.

Typical Test Formulae (from Clause 10.10):

• Compressive Strength, ( f_c ):

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

Where:

• ( P ) = Maximum load (N)

• ( A ) = Cross-sectional area (mm²)

• Tensile Strength, ( f_t ):

[ f_t = \frac{2P}{\pi d l} ]

Where:

• ( P ) = Load at failure (N)
• ( d ) = Diameter (mm)
• ( l ) = Length (mm)

This standard ensures uniformity in testing chemical resistant mortars for durability and performance.

IS 4456 Part 1: Apparatus and Materials Key Points

Apparatus (Clauses 5.2, 7.2 & 3.2.1-3.2.4)

• Basic apparatus as per Clauses 3.2.1 to 3.2.4 (not detailed here) plus additional equipment per 5.2 and 7.2.
• Ensure apparatus meets test-specific requirements for accuracy and suitability.

Containers (Clause 10.3.4)

• Wide mouth glass jars with plastic/plastic-lined metal screw caps for low temperature tests with low volatility solvents.
• Erlenmeyer flasks with standard taper joints and reflux condensers for volatile solvents.
• Containers must have:
  • Inert inner coatings or
  • Be made of inert materials like polyethylene for solutions that attack glass.

Conditioning of Materials (Clause 3.3)

• Store all test materials at 27° ± 2℃ for a minimum of 16 hours before use to ensure consistency.

Summary Table for Containers

This ensures reliable test results by controlling environmental conditions and preventing chemical interactions with containers.

Setting Time Determination as per IS 4456 Part 1

Key Definitions (Clause 2.1.2)

• Setting Time: Time (minutes) from start of mixing powder filler & liquid binder/resin at a given temperature until the Vicat needle (1 mm² tip or 1.13 mm diameter) fails to penetrate 5 mm into the test block in the mould.

Procedure Summary (Clauses 3.5, 4.3.2)

• Working Time (Clause 3.5):

  • Take ~15 g mortar samples every 5 min.
  • Trowel on a clean, dry surface.
  • Mortar is workable if it stays in place without curling behind the trowel.
  • Working time = time from mixing start until mortar stops being workable.

• Setting Time (Clause 4.3.2):

  • Place test block in mould on a non-porous plate.
  • Use Vicat needle with flat end (1 mm² or 1.13 mm dia).
  • Gently lower needle onto block surface and release.
  • Initially, needle penetrates fully.
  • Repeat until needle penetration is ≤ 5 mm from mould bottom.
  • Record this time as Setting Time.

Summary Table

Notes:

• Do not return tested mortar to mix.
• Tests done at specific controlled temperature.
• Use non-porous plate under mould for setting time test.

flowchart TD
    A[Start Mixing] --> B{Take 15g samples every 5 min}
    B -->|Mortar workable| C[Continue testing]
    B -->|Mortar not workable| D[Record Working Time]
    A --> E[Prepare test block in mould]
    E --> F[Lower Vicat needle]
    F --> G{Needle penetration ≤ 5 mm?}
    G -->

IS 4456 Part 1: Preparation and Moulding of Test Specimens

Key Specifications:

• Specimen size: 50 mm cube.
• Number of specimens: At least 6.
• Mould preparation:
  • Apply a thin coat of silicon grease or similar non-interfering material to inner surfaces to prevent sticking.
• Filling the mould:
  • Use a stainless steel spatula.
  • Place ~30 g of mortar initially, then work down vertically with spatula strokes to avoid air entrapment.
  • Use a thin narrow blade vertically through the mortar during filling to release trapped air.
• Finishing:
  • Strike off excess mortar evenly with the top of the mould using an oscillating horizontal stroke of a straight edge or spatula.

Summary Table:

flowchart TD
    A[Prepare Mould] --> B[Apply silicon grease]
    B --> C[Fill ~30g mortar]
    C --> D[Compact vertically with spatula]
    D --> E[Insert narrow blade vertically to remove air]
    E --> F[Fill remaining mortar]
    F --> G[Strike off excess with spatula]
    G --> H[Specimen ready for curing]

This ensures uniform density, no air voids, and accurate specimen dimensions per IS 4456 Part 1.

Flexural Strength Testing as per IS 4456 Part 1

Key Formula (Clause 6.5)

[ \text{Flexural Strength} = \frac{3Pl}{2bd^2} ]

• P = Load at breaking (kg)
• l = Span length (cm)
• b = Width of specimen at break (cm)
• d = Depth of specimen at break (cm)

Testing & Calculation Guidelines

• Specimen rejection: Defective specimens must be discarded (Clause 6.6.1).
• Outlier removal: Discard values differing by more than 15% from the average (Clause 5.8 & 6.6.1).
• Minimum data points: If fewer than 3 valid values remain after discarding, retest is mandatory.
• Average value: Calculate average flexural strength from all valid specimens of the same sample and age.

Summary Table for Validity Checks

This ensures reliable and consistent flexural strength results following IS 4456 Part 1.

IS 4456 Part 1: Compressive Strength Testing Key Points

1. Compressive Strength Calculation (Clause 7.7)

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

• Expressed in kg/cm².
• Load applied uniformly on specimen faces.

2. Specimen Testing Procedure (Clause 10.9.3)

• Use cylindrical specimens with plane faces in contact with compression tool.
• Load applied at 40 kg/cm²/min rate.
• Record maximum crushing load.
• Test sets of two specimens at:
  • End of conditioning period
  • After each inspection period per solution & temperature
  • After aging in air for total test period

3. Data Reporting (Clause 10.10.1.2)

• Show absolute compressive strength for initial and final specimens near each plot point.

4. Quality Control (Clause 6.6.1)

• Eliminate defective specimens.
• Average flexural strength calculated from remaining specimens.
• Repeat test if:
  • Any value differs by >15% from average
  • Fewer than 3 specimens used

Summary Table:

flowchart TD
    A[Start: Specimen Preparation] --> B[Conditioning Period]
    B --> C[Apply Load @ 40 kg/cm²/min]
    C --> D[Record Max Load]
    D --> E[Calculate Compressive Strength]
    E --> F{Values within ±15%?}
    F -- Yes --> G[Report Average Strength]
    F -- No --> H[Repeat Test]

This ensures reliable compressive strength data per IS 4456 Part 1.

IS 4456 Part 1: Preparation & Conditioning of Crossed Tile Test Specimens

Key Specifications:

• Tile Dimensions: 198.5 mm × 100 mm × 35 mm (rectangular shape)
• Drying: Oven dry at 105°C ± 5°C for 24 hours, then cool to 27°C ± 2°C
• Tile Assembly: Crossed at right angles, centered, with contact points marked for load test

Mortar Application (Clause 8.5):

• Apply mortar on marked tile area, 25-50% excess to ensure full joint
• Place mortared tile on flat surface with two blocks on each side for joint thickness control
• Blocks height = tile thickness + desired joint thickness (e.g., tile 35 mm + joint 5 mm = blocks 40 mm)
• Place second tile on top in a criss-cross pattern, compress until ends touch blocks, align mortar joints parallel
• Remove excess mortar, remove blocks carefully
• Allow mortar to set for minimum 24 hours

Conditioning (Clause 8.6):

• Condition specimens for 2 weeks at 27°C ± 2°C

Summary Table:

Diagram: Crossed Tile Specimen Setup (Fig. 6)

graph LR
A[Bottom Tile (Mortared side up)] --> B[Two blocks on each side]
B --> C[Top Tile placed crosswise]
C --> D[Compress top tile until ends touch blocks]
D --> E[Strike off excess mortar]

This ensures uniform joint thickness and proper alignment for testing.

IS 4456 Part 1: Absorption and Apparent Porosity Determination

Key Formulas

1. Absorption (%)
   [ A = \frac{W - D}{D} \times 100 ]

• W = Saturated weight of specimen (g)
• D = Dry weight after conditioning to constant weight (g)

2. Apparent Porosity (%)

• Using water:
  [ P = \frac{W - D}{W - S} \times 100 ]
  (Note: Clause 9.8.1a uses a simplified form; typically, S = suspended weight in water, but here simplified as below)

• Using water (as per clause 9.8.1a):
  [ P = \frac{W - D}{W} \times 100 ]

• Using toluene:
  [ P = \frac{V \times G}{W - D} \times 100 ]

• V = Volume of specimen (cm³)

• G = Specific gravity of toluene

• W, D as above

Reporting Requirements (Clause 8.9 & 9.9)

• Type of mortar tested
• Tile identification
• Age of specimen
• Number of specimens (usually six)
• Type of failure (cohesion/adhesion)
• Average bond strength
• Average % apparent porosity
• Average % absorption (water or toluene)

Summary Table

flowchart TD
    A[Specimen Preparation]
    B[Saturate specimen in liquid]
    C[Measure saturated weight (W)]
    D[Condition to constant

Chemical Resistance Testing (IS 4456 Part 1) Key Points

1. Retest Criteria (Clause 9.10)

• If a single specimen's value deviates >15% from the average, discard it.
• Recalculate average from remaining specimens within 15% deviation.
• If fewer than 4 specimens remain after discarding, repeat the test.
• Defective specimens are discarded.

2. Test Objective (Clause 10.1)

• Evaluate chemical resistance of silicate and resin type mortars under service conditions.
• Rapid assessment method.

3. Exposure & Inspection (Clause 10.9.2)

• Weigh specimens to ±0.0001 g before immersion.
• Record color and surface appearance of specimens and test solution clarity.
• Immerse specimens on curved sides in containers with ~150 ml test solution per specimen.
• Use even number of specimens per container.
• Maintain constant temperature (oven or liquid bath).
• Inspect specimens at 1, 7, 14, 28, 56, 84 days for attack nature.
• Test may end earlier if desired.

Summary Table for Inspection Intervals

Formula for Retest Average

[ \bar{X} = \frac{\sum X_i}{n} ]

Where:

• (X_i) = individual specimen value within ±15% deviation
• (n) = number of valid specimens (≥4)

This ensures reliability in chemical resistance evaluation per IS 4456 Part 1.

IS 4456 Part 1 (1967) - References to Related ASTM Standards

Key Points from Clause 10.12.1 & Appendix A:

• Test Data Requirements (Clause 10.12.1):

  • Average % weight change of specimens.
  • Appearance of specimens & immersion medium.
  • Average % change in compressive strength.
  • Graphs for % weight change and compressive strength vs. test duration.

• Relevant ASTM Standards (Appendix A):

Summary Table for Test Methods (IS 4456 Part 1):

Notes:

• Results should be rounded per IS 2-1960.
• The ASTM standards listed provide internationally coordinated test methods aligning with IS 4456.
• Use ASTM standards for detailed procedures and test parameter specifications.

flowchart TD
    A[IS 4456 Part 1 Tests] --> B[Working & Setting Time (Clause 4