Basic HTML Version
157
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
P. B. ARISTIMUNHO | S. R. BERTOCINI
ence, and the 10% replacement of cement was less impaired and
reached 17 MPa at 90 days.
3.4 Void ratio
Void ratio (ratio between pore volume and the volume of solids) is
directly proportional to the porosity of the material. Void ratio test
was carried out only for the group of sand replacements and the
reference, as shown in Figure 6.
It is observed that void ratio increases as the percentage of sand
replaced by iron ore in powder increases. A larger amount of fine
material affect the workability of the mortar and the compression of
the layers. The mixtures were prepared applying the same energy
of compression. An interesting suggestion is to apply higher en-
ergy of compression or use superplasticizer in sand replacements
mixtures in order to reduce the void ratio. In general, when the void
ratio decreases and, consequently, the porosity, the compressive
strength is increased (Neville [10]).
3.5 Specific mass
The specific mass results were showed and discussed only for
specimens with sand replacements, because this group presented
the most significant values, while the others groups practically
Figure 6 – Chart of void ratio of
sand replacements and reference
Figure 7 – Chart of specific mass
of sand replacements and reference
Figure 8 – Visual comparison of red color,
reference and sand replacements
Table 3 – Compression strenght, w/c ratio and consistency index of cement replacement and reference
Compositions
Mixture in mass
cement: sand: IO
powder
water/cement
ratio
Results of compression strenght
in MPa
Flow
Table
(mm)
7 days
28 days
90 days
OBS: IO=iron ore
Reference
1 : 3 : 0
0,60
16,14
24,55
24,36
243
Cement Replacement 10%
1 : 3,3 : 0,1
0,60
11,56
15,66
17,15
243
Cement Replacement 20%
1 : 3,75 : 0,25
0,60
10,1
8,75
16,51
242
Cement Replacement 30%
1 : 4,3 : 0,43
0,60
9,46
8,79
11,16
241