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Introduction

Equivalent cube test Objectives: Determine equivalent cube compressive strength of the concrete. Acquire an appreciation of the relation between equivalent cube compressive strength and other strengths such as cube compression strength, flexural tensile strength and splitting tensile strength. Test to be conducted: Determine compressive strength using equivalent cube method on a part of the beam broken in flexural tensile strength test in accordance with BS1881: Part 119: 1983. Specimen: Broken portion of beam from flexural strength test. Apparatus: Equivalent cube strength test jig, compressive testing machine. Procedures: a. The broken portions of the beams selected for the compressive strength test shall be have a length not less than 50mm greater than the width of the beam, be free from cracks, chipped surfaces or other obvious defects within the length to be tested. ...read more.

Middle

e. Apply the load without shock and increased continuously at a rate of approx 15 MN/m2 per minute until no greater load can be sustained. Record the maximum load. Calculations: Fig. 3.3.1 Typical device for "equivalent cube" test. Data: Area to be test: 150mm X 150mm The maximum load: KN Result: stress = N/mm Discussion: From the above results, we can see that the reading in test 1 and 4 (cube compressive strength test and equivalent cube test) has a small different. The reading in equivalent cube test was a little bit higher than that of cube compressive strength test. It can be explained by energy is needed to break the bonding between the forced concrete and the around concrete. ...read more.

Conclusion

As a result, equivalent cube test is a good method to exam the compressive strength of the specimen. Comparing the compressive strength to the tensile strength of concrete, the tensile strength is only 1/10 of its compressive strength. This reflects the fact that concrete is strong in compression but weak in tension. Rate of loading is quite important to the test compressive strength. In general, the higher the loading rate the higher the measured strength. It is thought that under slow loading rates more sub critical cracking may occur or that slow loading allows more creep to occur which increase the amount of strain at a given load. Conclusion: The compressive strength of the specimen is kN/mm2. It's about 10 times the tensile strength. And it is a little bit higher than the result obtained from the cube compressive strength test. ...read more.

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