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What is Modulus of Refracture?
The modulus or flexural strength that a material can withstand is measured as the highest bending stress which can be applied the material prior to it yielding. The elastic strength of a prismatic specimen can be determined through applying a bend force to it through the use of rollers with lower and upper sides.
Modulus or rupture can be described as a measurement of the strength of tensile force in concrete slabs or beams. Flexural strength is the measure of the amount of force and stress that a concrete slab, beam or other structure is able to be able to endure, so that it can withstand any bend failures. Modulus of rupture can also be called flexural strength, bend strength, or fracture strength.
Also Read: Contour Interval
Standard Test Methods for Determining the Modulus of Refracture of beams
To test the strength of flexural beams made of concrete, their span length must have at minimum three times its depth. The flexural strength is calculated in terms of the modulus for rupture (MR) in psi (MPa). There are two common tests to measure the strength of a flexural concrete beam.
1. Center point load test (as as per ASTM C 293)
In this method of testing the load is applied to the center in the span. The flexural strength also known as the modulus for rupture, is greater that the rupture modulus in the third point load test. The highest stress is found only in the middle of the beam.
2. Third point load test (as as per ASTM C 78)
In this test in this test, load will be applied on one third the length. The flexural strength, also known as modulus or rupture, is smaller than that of the rupture modulus observed at the center of the load test. The greatest stress is found in the center of one-third of the beam.
The modulus of rupture of flexural flexibility is approximately 10% to 20% of compressive strength, based on the kind and size of coarse aggregate that is used in the concrete beam. The best connection for particular materials is determined by testing in the laboratory for the particular mix and materials. Modulus of rupture measured by third point loading is less that the rupture modulus measured using center-point loading at times by up to 15 percent.
Also Read: Floating Slab
Refractory Lining Systems
Strength
Modulus of Refracture (psi kg/cm2)
Modulus of rupture (MOR) is similar to an tri-point bend. MOR determines how strong the bonds of the specimen being tested. For castables, it evaluates the strength of bonding in that cement matrix. The size of the particles and the packing that the aggregate is packed with play a role in MOR, however the strength of cement bonds adds more to the MOR value.
Hardness of Crushing Cold (psi kg/cm2)
The cold crushing strength (CCS) is a test for compressive strength that determines the capability of a material to stand up to a certain amount of load. It is typically determined at room temperature following firing at certain temperatures. CCS is measured using ASTM C133. The distribution and packing of particles are crucial in the development of solid CCS. Cement maturity although important, it doesn't affect this measurement as significantly as MOR. Products that produce good CCS are not always acceptable due to other physical property issues.
Also Read: Spread Footing
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