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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 6
A. B. ROHDEN | D. C. C. DAL MOLIN | G. L. VIEIRA
with other equipment and, especially, with a greater volume of
concrete mixes.
However, it is important to emphasize that the employment of su-
perplasticizers, along with regular agitation, allowed the casting
of the concrete to be done over a time interval 2.5 times longer
than what is prescribed by NBR 7212, while maintaining its me-
chanic performance.
4. Conclusions
This study shows that differently from the standards set by
NBR 7212 and from what is widely indicated in the literature,
the concrete casting and finishing time can be extended be-
yond150 min, to up to 360 min, as long as slump is maintained
through the use of superplasticizers (maintaining the water/
Figure 4 – Compressive strength of the concrete
made with CPIV, at seven days
Figure 5 – Compressive strength of concrete
at twenty eight days, made with CP IV
Table 4 – Variance analysis
Source
Test
SQ
GDL
MQ
F
Probab
Comment
A: Type of cement
8780.53
1
8780.53
519,32
0.00%
S
B: Breaking age
2787.30
1
2787.30
164,85
0.00%
S
C: Compacting time
1056.91
5
211.38
12.50
0.00%
S
D: Mix proportion
1792.62
2
896.31
53.01
0.00%
S
AB
24.48
1
24.48
1.45
23.09
NS
AC
258.96
5
51.79
3.06
1.18%
S
AD
262.74
2
131.37
7.77
0.06%
S
BC
146.57
5
29.31
1.73
13.09%
NS
BD
77.52
2
38.76
2.29
10.49%
NS
CD
241.03
10
24.10
1.43
17.52%
NS
ABC
65.99
5
13.20
0.78
56.54%
NS
ABD
108.75
2
54.37
3.22
4.32%
S
ACD
406.53
10
40.65
2.40
1.16%
S
BCD
414.57
10
41.46
2.45
1.00%
S
ABCD
284.74
10
28.47
1.68
9.03%
NS
Error
2316.35
137
16.91
–
–
–
–
–
–
–
Total
19025.58
208