What is the standard diameter for the loading and support rollers?

The rollers shall be 38 mm in diameter (Clause 4.1).

What is the required accuracy of the flexural testing machine?

The machine's accuracy must be within ±2 percent of the indicated load at all stages of loading (Clause 7.1).

Does this standard specify the rate of loading?

No, this standard specifies the apparatus. The rate of loading is specified in the relevant testing method, such as IS 516.

What is the required hardness for the rollers?

The roller and bearing plate surfaces must have a hardness of not less than 550 HV (Vickers Hardness) as per Clause 4.2.

IS 9399

: 1979

Specification for apparatus for flexural testing of concrete

CurrentSpecializedSpecificationMaterials Science · Cement, Concrete, Aggregates and RCC

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This standard specifies the requirements for the apparatus used to conduct flexural strength tests on concrete beams. It details the machine frame, load application methods (two-point and central), dimensions and material of rollers, and the accuracy of the load indicating system.

Specification for apparatus for flexural testing of concrete

Quick Reference Values

Loading Machine Accuracy±2% of indicated load

Standard Roller Diameter38 mm

Roller and Bearing Plate Hardness> 550 HV

Roller LengthAt least 10 mm greater than the width of the test specimen

Distance between two-point loads200 mm for 150mm specimen, 133 mm for 100mm specimen

Practical Notes

This code is for the apparatus itself; the testing procedure and calculation of flexural strength (modulus of rupture) are covered in IS 516.

The code allows for two loading methods: two-point (third-point) loading and central loading. The former is more common as it subjects a larger portion of the beam to maximum bending moment.

Ensure rollers are clean, free to rotate, and properly aligned to prevent inducing torsion or stress concentrations during the test.