Page 84 - Riem-Vol6_nº2

255 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 2
L. P. PERLIN | R. C. A. PINTO
Figure 16 – CP3 Tomogram– (a) specimen and location of analised section
(b) tomogram – (c) legend in m/s
A B C
Figure 17 – CP4 Tomogram – (a) specimen and location of analised section
(b) tomogram – (c) legend in m/s
A B C
that the EPS size is the cause of such changes in the tomograms.
The ray-paths in CP1 probably travel not only surrounding the
sides of the EPS block, but also above and below it, depending
on the reading. This does not occur in the readings performed on
CP2. As an example, in CP1, the estimated travel length of the
wave propagation surrounding the EPS block at its top face is 25.6
cm while the same length through the lateral side is 25.9 cm, as
shown in Figure 18-a. Thus, the faster ray-path passes through the
top face of the EPS block.
On the other hand, the height of EPS block in specimen CP2 pre-
vents the faster ray-paths to travel through the top side of the EPS
block since the total distance for this route is 27.5 cm while the
distance through the EPS side is 25.9 cm (Figure 18-b). This dif-
ference between the EPS blocks of CP1 and CP2 generates larger
ray-path to readings in CP2, explaining the observed stronger vio-
let region in tomogram of Figure 15, when compared with the to-
mogram of Figure 14.
The tomogram of CP3 specimen (Figure 16) shows an oval shape
low velocity region, with the greatest dimension perpendicular to
the EPS block inserted. The ultrasound readings that pass through
the center of EPS are the most affected by its rectangularity.
Therefore, these readings yield slower velocities; the tomography
process takes this slowness to the grid elements at the center of
the EPS and to perpendicular regions nearby. This effect is called