How To Calculate Flexural Strength Of Concrete?
How To Calculate Flexural Strength Of Concrete?
Flexural strength, also known as modulus of rupture, is an important measure of the tensile strength of concrete. It is used to determine the ability of concrete to withstand bending or flexing without breaking.
The flexural strength of concrete is typically lower than its compressive strength, making it a critical factor to consider in structural design.
To calculate the flexural strength of concrete, you can use the following formula:
Flexural Strength = (3 * Load * Length) / (2 * Width * Thickness^{2})
Where:
 Load is the maximum load applied during the flexural strength test
 Length is the length of the concrete specimen
 Width is the width of the concrete specimen
 Thickness is the thickness of the concrete specimen
The flexural strength of concrete can be determined through a flexural strength test. This test involves applying a load to a concrete specimen and measuring the load at which the specimen breaks. The test can be conducted using either a onepoint loading test or a twopoint loading test.
Key Takeaways:
 Flexural strength is a measure of the tensile strength of concrete.
 It determines the ability of concrete to withstand bending or flexing without breaking.
 The flexural strength formula is (3 * Load * Length) / (2 * Width * Thickness^{2}).
 A flexural strength test can be conducted using a onepoint loading test or a twopoint loading test.
 Calculating the flexural strength is crucial in structural design and construction.
Experimental Estimation of Flexural Strength of Concrete
The experimental estimation of flexural strength involves conducting tests on concrete specimens to determine their ability to withstand bending or flexing without breaking. Two commonly used tests for estimating flexural strength are the onepoint loading test and the twopoint loading test.
In the onepoint loading test, a concrete specimen is supported at two points and a load is applied at the center of the specimen until it breaks. This test provides valuable information about the flexural strength of the concrete.
The twopoint loading test, on the other hand, involves supporting the concrete specimen at two points and applying a load at a predetermined distance from one of the support points. This test helps in determining the flexural strength of the concrete and its ability to resist bending.
To calculate the flexural strength of concrete, the maximum load applied during the test is divided by the crosssectional area of the specimen. This calculation provides a measure of the concrete’s resistance to bending and is an important factor in structural design.
Comparison between OnePoint Loading Test and TwoPoint Loading Test
Test  Procedure  Advantages  Disadvantages 

OnePoint Loading Test  A load is applied at the center of the specimen 


TwoPoint Loading Test  A load is applied at a predetermined distance from one support point 


“The experimental estimation of flexural strength through the onepoint loading test and the twopoint loading test provides valuable insights into the behavior of concrete under bending conditions. These tests help engineers and designers assess the structural integrity of concrete elements and make informed decisions during the design process.” – Concrete Testing Expert
Significance of Flexural Strength in Structural Design
The flexural strength of concrete holds significant importance in structural design and construction. While concrete has excellent compressive strength, it tends to be weaker in tension. This is where the flexural strength comes into play, as it measures the ability of concrete to resist bending or flexing without fracturing.
One of the main reasons why flexural strength is crucial in structural design is because concrete structures are subjected to various loads and forces that can cause bending. Whether it’s a bridge, a beam, or a slab, understanding the flexural strength is vital for ensuring the durability and safety of the structure.
Increasing the flexural strength of concrete can be achieved through various methods. One common approach is the inclusion of reinforcement steel, such as rebar, within the concrete. The steel provides additional tensile strength, effectively supporting the concrete in resisting bending forces. The use of fiber reinforcements, such as glass or polypropylene fibers, can also enhance the flexural strength of the concrete.
Moreover, proper mix design and curing techniques play a significant role in increasing the flexural strength of concrete. By optimizing the proportion of cement, aggregates, and water in the concrete mix, engineers can achieve a higher flexural strength. Additionally, implementing careful curing practices, such as moist curing or utilizing curing compounds, can enhance the overall strength and durability of the concrete.
FAQ
What is flexural strength?
Flexural strength, also known as modulus of rupture, is a measure of the tensile strength of concrete. It determines the ability of concrete to resist bending or flexing without breaking.
How is flexural strength of concrete determined?
The flexural strength of concrete is typically estimated through the onepoint loading test or the twopoint loading test. Concrete specimens, usually rectangular in shape, are cast and cured for 28 days before testing.
Why is flexural strength important in structural design?
The flexural strength of concrete plays a crucial role in structural design and construction. While reinforcement steel helps increase the tensile strength of concrete, flexural strength is important because steel alone cannot handle the extreme fiber stresses in the member.