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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 1
M. K. EL DEBS | E.K. BELLUCIO
3.3 Mortar characterization tests in strips of pads
As described, the mortar placement in the molding of the pads was
performed manually (Figure 3) and also by vibration table. The de-
molding process was performed after two days of the molding, be-
ing placed for 24 hours in a humid chamber. Then, the samples
were removed from the humid chamber and placed at room tem-
perature until the day of the testing. The tests were performed after
14 days of the molding.
a) Concentrated load
This concentrated load test was derived from tests performed
by Montedor [5] and Siqueira [6] in order to measure the ca-
pacity of accommodation under concentrated loads on strips
of composite pad, or accumulated deformation. This test was
performed to compare the influence of fiber in the accommoda-
tion capacity.
These tests consist in cutting pads of 150mm x 150mm into strips
of 25mm x 150mm, in which loads are applied at two points lo-
cated at 37.5 mm from the edge of the strip. The load is ap-
plied by the deformation control machine at a rate of 0.01mm/s.
For each mixture, 10 strip samples of pads are tested, obtaining
the load
versus
displacement curve for each sample.
b) Bending tests
These testswere performed to verify the performance of themortar to
bending. The bearing capacity after cracking due to the influence of
the fibers was also verified. Six tests were conducted for each mix-
ture and each sample was 150mm x 12mm with 30mm wide.
Although performing specific tests on pads, the require-
ments of ABNT NBR 12142:1991 [11] were established
as a standard for the test. Thus, the same measures of
support distance and load application according to
ABNT NBR 12142:1991 [11]. The support were placed at
1cm from the edge of the sample and the points of load
application were 1/3 support of the brand. The load was
applied to a deformation where the pad began to lose
load. To compare the results, stress versus displacement
curves were designed and the performance of the speci-
mens was verified.
3.4 Bearing pads tests
a) Monotonic loading
In this case, six pads of 150mm x 150mm were molded for
each mixture and for each roughness. The load was applied to
the limit of the machine (1500 kN).
The purpose of these tests is to analyze the performance of the
pad, which is conventionally named stiffness. The relation can
be made from the diagram stress
versus
deformation. How-
ever, as the displacement is concentrated on the surface of the
pads, a stress
versus
displacement analysis was performed.
With the diagram stress
versus
displacement a curve is ob-
tained. Along the curve, a line is drawn past many points, start-
ing where the variation of the curve tends to a straight line.
The straight line is drawn once the pad is accommodated due
Figure 7 – Results of characterization tests in cylindrical specimens
A
B
C
Table 1 – Results of characterization tests
Mixture
Compression - MPa
Tensile - MPa
Modulus of Elasticity - GPa
PP12
40,9
3,1
12,8
Reference
79,5
3,6
23,2