A structure has been designed based on the compression strength of concrete. So mostly, the tensile strength of concrete tests are not required to perform at the site. The framed structure built up by the combination of brittle and ductile material.
The concrete is good in compression force and weak in tension force. So the reinforcement has been provided in concrete to prevent the crack formation.
The concrete’s ability to withstand pull force (Tensile Stress) without breaking is called the Tensile Strength of concrete. The tensile strength of concrete is measured by the units of Force per Cross-Sectional Area (N/Sqmm or Mpa).
As above said, the concrete is weak in tension force because of its brittle nature.
The concrete is formed by the mixture of different material cement, fine & coarse aggregates. Each material contains different properties, which results in the properties of concrete as a whole.
During the period of concrete casting, the water-cement ratio gradient makes around the aggregate particles, and the cement paste forms a different microstructure around the concrete. This zone is called the Interface Transits Zone.
The ITZ is the weakest zone of concrete because the bond between the cement paste and aggregates may be reduced due to concrete bleeding. In compressive stress, the load transferred from one aggregate to another aggregate, and that was not required for unprecedented strength.
At the same time, in tension force, the aggregate pulls away from each other, and it can be easily broken from its shape.
The tensile strength of concrete is an important property when it is to be used in making prestressed concrete structure, roads, and runways, this test shall follow as per the IS Code 5816.
The tensile strength of concrete is generally in the range of 10 % to 12% of its compressive strength.
The concrete cube was used to find the compressive strength of concrete, but to find the tensile strength of concrete a cylindrical specimen has to be used.
The direct tensile strength of concrete is difficult to measure. So we use split tensile strength tests.
An indirect method to determine the tensile strength of concrete using a concrete cylinder that splits across the vertical cross-section is known as split tensile strength.
Why?
Because in the direct tensile strength tests, it is impossible to apply axial load in the cube, there will always be some eccentricity. The stress applied to the concrete also tends to break it at ends. But we don’t use concrete alone; we use it with reinforcement where the load acts at the centre, not at the ends.
The below formula calculates the tensile strength of concrete
Fct – Tensile Strength of Concrete
P – Maximum load in N/Sqmm
L – Length of the Specimen
D – Diameter of the specimen
The split tensile strength test gives 5-10% higher value than the direct tensile strength test.
The testing report should have the following
Date | Grade | Age of Test | Specimen | Weight in Newtons | Load (kN) | Tensile Strength Kg/Sq.cm | Average Strength |
DD/MM/YY | 28 Days | Sample 1 | |||||
M25 | 28 Days | Sample 2 | |||||
28 Days | Sample 3 |
Happy Learning 🙂
Before starting any civil engineering work, regardless of branches, horizontal, vertical, and angular measurements of…
The data measurements gathered from surveying helps establish the plan and design of all civil…
Surveying is the art and science of civil engineering that determines the relative (comparable) position…
The formation of cracks on the concrete surface may lead to reduce the durability of…
Understanding the different levels of structure seems a bit of a daunting task. Don’t worry…
We knew that pipes are used to transport gas or liquid substance from one place…
View Comments
Should the specimen be cylindrical. Seems to be the same CTM used for this.
No!.. universal testing machine has to be use for Tensile Test