3 – Laboratory experimental program The compressive strengths in direction X and in direction Y are the same, and in direction Z is slightly lower. This also happened for cubic specimens. The analyzed bricks have a low anisotropy, but it can be assumed that the direction Z is the weakest.
3.3.5 Flexural tests on prismatic specimens of brick The flexural tests on prisms were performed following the standard UNE -EN 772-6, which is usually used for mortar specimens (section 3.1.3 of this thesis). Prismatic specimens were cut from the bricks using a circular saw (Fig. 3.3.7.b) then a small incision at the center of the specimen was made, with the aim to localize there the failure. Rupture occurs when the ultimate tensile strength is reached. The directions of traction are X and Y (Fig. 3.3.11.a and .b), because these are in reality the directions along which the brick normally works. The tests were carried out using the IBERTEST with load cell of 10 KN (Fig 3.3.11.c) and rupture always occurred in the center (Fig. 3.3.11.d).
Figure 3.3.11 – Flexural tests; a) Traction direction Y; b) Traction direction X; c) Support for the test in the IBERTEST (load cell 10KN); d) Failure mode (rupture of the middle section).
The flexural strength is calculated like:
Where:
,
[ ], ,
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