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**What Is Tensile Strength of Concrete**?

**Concrete tensile strength** is the **ability** of concrete** **to resist** tensile force or stress **applied to it.** **The tensile strength of **concrete **is **measured **by the** split cylinder test **of the concrete method. The **tensile strength of concrete** is measured by the **Units of Force per Cross-Sectional area (N/Sq.mm. or Mpa).**

As we know that **concrete **performance in **compression **is good, but weak in** tension force**. To counterbalance, this **situation **reinforcement has been **provided **in concrete to prevent **crack formation.**

**Read More:** **How to Check Compressive Strength of Concrete**

**Why is Concrete Weak in Tension?**

**Concrete** is not a single **solid material** like steel which is **strong **in both **tension **as well as **compression**. It is manufactured by **mixing **cementing **materials**, water, and **aggregate **(and **sometimes **admixtures).

**Interfacial Transition Zone**

The **“interface transition zone”** is the **weakest **link in the structure. When **compressive stress **or force is **applied **to the **zone**, aggregate transfers the **load **from one to another. So, **concrete **in compression does not **require **much strength to **resist compression stresses**.

In the case of **tensile stresses **developed in **concrete**, the aggregates are **trying **to **pull away** from each other so this **interfacial **transition zone has to **bear** tensile stresses to hold the **whole **system together. Since the **strength **of this **interface **zone is **weaker** than the **aggregates**, so the failure **starts **at much** lower stresses.**

**As per IS 456:2000,** the** tensile strength of concrete** is given by the equation.

The **tensile strength **of concrete under **direct tension **is roughly taken as **one-tenth** of the strength of **concrete under** compression.

**Read More:** **Rebound Hammer Test & Concrete Strength Calculation**

**Factors Affecting Tensile Strength Concrete**

**Quality of Raw Materials – Cement, Sand & Aggregate.****Water Cement ratio****Coarse to fine aggregate ratio****Aggregate cement ratio****Age of Concrete****Compaction of concrete****Temperature****Relative humidity****Curing**

**Tensile Strength of Concrete Test Methods**

**For the tensile strength of concrete, we can use the following test methods**

**Uniaxial Tensile Test**: This is a**direct tension**test in which a**concrete specimen**is held at the**ends**and**pulled**apart, inducing uniaxial**tensile stress**in it. the uniaxial**tensile test**is one of the most**difficult**and complicated tests to**perfume**on concrete but gives the**true tensile strength**of concrete.**Split Cylinder Test**: In this test, a**concrete**cylinder is placed**horizontally**between**loading surfaces**and**loaded**along its**diameter**. This loading results in producing**lateral tensile stress**in the**cylinder**and its**splits**in tension along its**diameter**. Refer to ASTM C 496 for the**split cylinder**test procedure.**Flexure Test:**In this test, a**concrete beam**is subjected to**four-point**loading and loaded to**rupture**. The specimen**cracks**due to tensile**stresses**induced in the**bottom**fibers under**pure bending**. This**gives**Modulus of**Rupture**of Concrete. It is performed as per**ASTM C78**. For the**flexure test**, another test is available in which**load**is applied by**center point**loading as per**ASTM C 293**. This test also provides**flexural strength**which will be**slightly**higher than the**4-point load test.**

**Tensile Strength of Concrete Test**

The **tensile strength **of concrete is **measured **by the split cylinder test of the **concrete method **and is one of the **major properties **of concrete, **especially **in the case of making **roads **and **runways**.

The tensile strength of **concrete** generally varies from **10 % to 12% **of its compressive **strength**.

For **determination **of **compressive strength of concrete cube**, samples are **used **and for testing tensile strength **generally**, cylindrical **samples **are cast.

**Specification of Tensile Strength Test**

**Specimen**

The **cylindrical concrete **specimen has a **diameter **of **150 mm** and a length of** 300mm.**

**Range of Load**

The **loading Machine **can apply a **constant **load range of **1.2 MPa/min to 2.4 Mpa/min.** (Generally, the **test **is conducted on the **universal** testing machine).

**Age of Test**

The **test **should be **conducted **at the age of **7 days **and **28 days**.

**Number of Specimen**

For **better results **comparison at least **3 samples **should be **tested**.

**Apparatus**

**Testing Machine (1.2 Mpa/min to 2.4 Mpa)****Tamping Rod (Dia – 16mm, and Length – 600mm)****Concrete Mould (Made by Steel)****Trowel**

**Sample Preparation**

- Take a
**sample**from a**good-quality**mix of**concrete**. - Clean the
**cylindrical**mold and**ensure**the mold is**free**from dust and**rust**. - Fill the
**mold**with concrete in**three equal**layers by proper**compaction**with the help of a**tamping**rod. - Keep the top
**surface**of the**concrete**smooth with the**trowel**.

**Curing**

**Mold**with concrete**samples**should be**covered**with wet**gunny bags**or kept in**undisturbed**water for 24 hours at a**temperature**of**27 ° Celsius ± 2.**- At the end of
**24 hours**take out the sample and**remove**the concrete**samples**from the mold and it should be**immersed**in the water for**7 or 28 days**based on the test. - Take out a
**sample**from the**water**after**24 hours**prior to the test and it**should**be in**dry condition.**

**Read More:** **Concrete Cube Fails in Test After 28 days**

**Tensile Strength Test Procedure**

The procedure for split tensile strength of concrete as per is 456 is given below,

- The bearing surfaces of the machine and the loading strip are free from dust.
- The specimen should be weighed in Newton prior to the test.
- Now, place the specimen centrally between the loading strips and ensure the upper platen is parallel to the bottom platen.
- Then apply the load gradually until the specimen break and note down the Value.
- The same method has been repeated for other samples

**Tensile Strength of Concrete Formula**

The formula for the tensile strength of concrete is given below,

Fct – Tensile Strength of Concrete

P – Maximum load in N/Sqm

L – Length of the Specimen

D – Diameter of the specimen

**Report**

The testing report should include the following details,

- Age of the Test
- Date of specimen cast
- The weight of the specimen
- The grade of concrete

## FAQs: Tensile Strength of Concrete

### Tensile Strength of Concrete

Concrete tensile strength is the ability of concrete to resist tensile force or stress applied to it. The tensile strength of concrete is measured by the split cylinder test of the **concrete** method. The **tensile strength of concrete** is measured by the **Units of Force per Cross-Sectional area (N/Sq.mm. or Mpa).**

### Tensile Strength of Concrete is Measured by

It Is a measured **Split cylinder test of the concrete** method and its measuring unit is force per cross-sectional area **(N/Sq.mm. or Mpa).**

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