For the 7-day/splitting tensile test lab report: 1) Discuss the importance and a
ID: 1713138 • Letter: F
Question
For the 7-day/splitting tensile test lab report: 1) Discuss the importance and applications of 7-day strength tests 2) Explain the basic mechanics behind a splitting cylinder test. Why do tensile stresses form in the specimen? How are the tensile stresses related to failure? 3) What type of failure modes did you observe in the compression tests of the concrete cylinders? When the cylinders failed did they have vertical cracks, diagonal cracks, serval types of cracks, etc. What caused the failure modes you observed? A short discussion on the subject is shown on the last 2 pages of this printout. You may find it useful for vour discussiornExplanation / Answer
1. Importance of the Test:
The concrete is very weak in tension due to its brittle nature and is not expected to resist the direct tension. The concrete develops cracks when subjected to tensile forces. Thus, it is necessary to determine the tensile strength of concrete to determine the load at which the concrete members may crack.
In direct tensile strength test it is impossible to apply true axial load, there will be always some eccentricity will be present. Another problem is that stresses induced due to grips, due to grips there is a tendency for specimen to break at its ends.
2. Basic mechanism behind the test:
The test consists of applying comprehensive line loads along opposite generations of concrete cylinder placed with its axis horizontal between the patterns. Due to the applied line loading a fairly uniform tensile stress induced over nearly two-third of load diameter as obtained from elastic analysis. The magnitude of tensile stress (acting in a direction perpendicular to the line of action of comprehensive load) is given by 0.637P/DL. Where P is applied load, D is diameter and L is length of the specimen. Due to tensile stress the specimen fails finally by splitting along the loaded diameter and knowing P at failure.