Flexural Strength of Concrete Test (Hardened Concrete) as per Indian Standard

Flexural Strength of Concrete Test (Hardened Concrete) as per Indian 

Standard

Key Concepts

• Flexural Strength: A measure of a concrete slab's ability to resist deformation under load.
• Hardened Concrete: Concrete that has set and developed significant strength.

Test Procedure

1. Specimen Preparation:

   • Size: Typically 100 x 100 x 500 mm for standard samples.
   • Curing: Ensuring the specimen is properly cured before testing.

2. Test Setup:

   • Placing the specimen on two support points.
   • Applying load at the midpoint (for 3-point loading) or at third points (for 4-point loading) of the span.

3. Loading Rate:

   • Apply load gradually without shock, maintaining a constant rate until failure.

4. Failure Identification:

   • Note the maximum load (P) the concrete can withstand before cracking and breaking.

Formulas and Calculations

• Flexural Strength (f):
  • Three-point loading: $f=\frac{PL}{b{d}^2}$
  • Four-point loading: $f=\frac{3Pa}{b{d}^2}$
  • Variables:
    • $P$ = Maximum load at failure (N)
    • $L$ = Length of the span (mm)
    • $b$ = Width of the specimen (mm)
    • $d$ = Depth of the specimen (mm)
    • $a$ = Distance between the load application point and nearest support (mm)

Standards Referenced

• Indian Standard (IS) 516: Provides guidelines for conducting tests on concrete.

Important Considerations

• Ensure proper alignment and placement of specimen to avoid eccentric loading.
• Maintain humidity and temperature conditions as prescribed in standards for accurate results.
• Cement type, aggregate type, and water-cement ratio can influence flexural strength.

These notes cover the fundamental aspects of conducting and calculating the flexural strength test for hardened concrete as per Indian standards.