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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 5
Mechanical behavior analysis of small-scale modeling of ceramic block masonry structures –
Geometries effect
The granulometric distribution of sand used in the experimental
tests followed the recommendations of BS 1200 [14]. Portland ce-
ments CP II- F-32 and CH-III-type hydrated lime were used. Deter-
mination of the unitary mass of the cement and the lime followed
the procedures described by NBR 7251 [15]. Table 04 shows the
values of the unit masses of cement, lime and sand.
The geometries of the blocks had the following characteristics:
1 – Block type A –a model with two rectangular hollows similar to
the format of concrete block;
2 – Block types B and C – both types with two circular hollows.
The block type B maintains the same thickness for the face
shell and cross webs, resulting in a higher net area. For block
type C the net area was maintained equal to the block type A;
3 – Block type D –a model with two rectangular hollows. The in-
ternal cross webs thickness is double the thickness of the face
shell plus that of the mortar joint. This causes a meeting on
the vertical joints of the mortar.
The relationships between the different net areas of the blocks are
presented in Figure 13, where it can be observed that the relation-
ship between the net and gross area of blocks A and C (BA/BC)
Figure �� � �risms and �alls for e�aluation
of the influence of geometry on masonry
(dimensions in cm)
are 1.0, that is, both blocks have the same relationship between
the net and gross area.
The walls were built with an apparatus that ensured that the blocks
were level, aligned and vertical in each row, following the recom-
mendation of NBR 8949 [16]. Table 14 presents the first and sec-
ond rows with the apparatus for execution of the wall. For the dif-
ferent types of blocks, five prisms with and without vertical joint
and three walls were built for each type of mortar, as shown in
Figure 15. Table 05 presents the descriptions of the different tests
of blocks, prisms and walls. The designation PA1 indicate the
prisms with block type A and mortar I while the designation PPB2
indicates a masonry wall built with block B and mortar type II. The
designation code is as follows: A, B, C, D = block, P = prism; PP =
masonry wall; 1 = mortar type 1:1:6; and 2 = mortar type 1:0.5:4.
Due to the difficulties of implementing tensile tests on the blocks, it was
decided to obtain the tensile strengths of the blocks indirectly by dia-
metric compression as shown in American Standard ASTMC1006-84
[17]. The cylindrical steel bars required for the tests were between 1/8
and 1/12 of the height of the sample and had lengths greater than their
widths. The bars were aligned with the central crossing web in each
block. The load applied at a rate of 0.33 MPa/min. The tensile strength
was then determined by using Equation 01.
(1)
f
t
=
H.L.
P.2
Where:
f
t
= tensile strength by diametric compression (MPa); P =
applied load (kN); L = length (mm); and H = height of the sample.
Values of the tensile strength determined by diametric compres-
sion are presented in Table 06, together with a depiction of the
test device.
Sixteen blocks of each geometry were randomly selected for the
compression tests. Blocks were prepared for testing by the follow-
ing procedure:
– the top and bottom of the blocks were covered with a mixture
of 70% cement paste plus 30% sand retained in the 0.15 mm
sieve to avoid cracking caused by shrinkage;
– after the capping of the top and bottom of the blocks the speci-
mens were immersed in water for 24 hours;
– excess water was removed with a dry rag before the tests
Compression tests were performed by incrementally applying the
load at a rate of 0.5 MPa/second. The compressive strength of the
gross area gives a standard strength for a constant area that is
independent of geometry effects.
Ta�le � � Denomina�ions o� �locks, mor�ar, prisms and walls
Block
Type A (BA)
Type B (BB)
Type C (BC)
Type D (BD)
Prism
Mortar I
PA1
PB1
PC1
PD1
Mortar II
PA2
PB2
PC2
PD2
Wall
Mortar I
PPA1
PPB1
PPC1
PPD1
Mortar II
PPA2
PPB2
PPC2
PPD2