Concrete Flexural Strength

Concrete Flexural Strength

Concrete is basically used under compressive stress and the tensile forces are absorbed by reinforcement bars. Concrete itself has some tensile and flexural strength, which is strongly dependent on the mix. The critical factor is the bond between aggregate and hydrated cement. Concrete has a flexural strength of approximately 2 N/mm²  to 7 N/mm²

Influences on flexural strength

Flexural strength increases

·     As the standard cement compressive strength increases (CEM 32.5; CEM 42.5; CEM 52.5)

·     As the water/cement ratio falls

·     By the use of angular and broken aggregate

Applications

·     Steel reinforced fiber concrete

·     Runway concrete

·     Shell structure concrete

Test methods

Principle:- A bending moment is exerted on prism test specimens by load transmission through upper and lower rollers.

·     Prism dimensions:

Width = height = d

Length > 3.5 d

Two test methods are used:

·     2-point load application

Load transfer

above through 2 rollers at a distance d (each one ½ d from centre of prism).

The reference method is 2-point load application.

·     1-point load application (central)

Load transfer above through 1 roller, in centre of prism.

In both methods the lower rollers are at a distance of 3 d (each one 1½ d from centre of prism).