Basic HTML Version
42
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 1
Cement-base bearing pads mortar for connections in the precast concrete: study of surface roughness
lished, in volume, for the mortar (PP12): 1:0.285:0.35:0.02 (Port-
land cement: sand: water, superplasticizer), V15L20F2 added
(1.5% of expanded vermiculite-term, 20% of latex and 2% of
polypropylene fiber). The studies also included a reference mix-
ture, no fibers and expanded vermiculite-term, adding the amount
of water contained in the latex emulsion, and analyzing the in-
fluence of these components. The proportion for this mixture is
1:0.3:0.35:0.01 (Portland cement: sand: water: superplasticizer).
3.2 Standard Tests for Mortar Characterization
a) Simple Compression
The simple compression tests were performed in cylindri-
cal specimens of 100mm x 50mm, according to the recom-
mendations of ABNT NBR5739/2007 [9] with loading rate at
0.005 mm/s.
b) Tensile strength by diametral compression
These tests were performed on cylindrical specimens of
100mmx50mm, according to the recommendations of ABNT
NBR7222/1994 [10], with patterned loading rate at 0.005 mm/s.
c) Modulus of Elasticity
This test is performed by applying an axial load to the cylindri-
cal specimens. The application is performed in a circular area of
50 mm diameter and two transducers with rods of 50mm are
used, placed on opposite sides of the specimens to be test-
ed, approximately 25mm from the base of the 100mm speci-
mens. Thus, the stress
versus
strain diagrams are made from
the load obtained in the acquisition system of the machine and
the average of the two displacement transducers. From the curve
representing stress
versus
strain and the equation curve (re-
gression) the modulus of elasticity can be obtained. The regres-
sion is made between 5% and 50% of the maximum load of the
specimen. Figure 4 shows a typical diagram.
Figure 5 – Monotonic loading test
A
B
Test scheme
Stress versus deformation diagram to obtain pads stiffness
Figure 6 – Diagram of the cyclic
test showing stiffness calculation and
accumulated deformation to stress of 20 MPa
Figure 4 – Stress versus strain diagram
to obtain the modulus of elasticity