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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 4
B. F. TUTIKIAN | M. PACHECO
workability tests were conducted, in compliance with ABNT NBR
15823:2010 [4], and it was concluded that the values were within
the acceptable limits. The final admixture/binder ratio in the mix-
ture was 0.85.
It should be noted that for this method it was possible to create
only one unit composition for the SCC mixture, since this method
does not mention how to quantify auxiliary unit compositions for
the dosage.
Table 1 shows the unit composition for this method.
3.1.2 Repette-Melo Method [2]
The flowchart for obtaining the SCC mixture by this method of dos-
age is shown in Fig. 2.
The initial step for making the SCC mixture is the paste composition,
by determining the water/cement ratio and the amount of fines added.
n% is the superplasticizer/binder ratio, C is the amount of cement
per m³ in the mixture, m% is the amount of solids in the superplas-
ticizer, Wsp is the amount of superplasticizer admixture used, and
Wasp is the amount of water in the superplasticizer admixture.
Considering Wsp = 2.75 kg/m³ worth of superplasticizer admixture,
the amount of water existing in the admixture is calculated using
Equation 8.
(8)
W
asp
= (1 - m%)*W
sp
The result was Wasp = 1.65 kg/m³ worth of water existing in the
admixture.
Considering the amount of water existing in the superplasticizer
admixture, the initial water consumption in the mixture became
197.65 kg/m³.
Taking into account all the ratios determined for the SCC composi-
tion, the materials were then taken into the lab for dosage, with a
unit composition test as the initial step. It is important to observe
that the only amounts which may be altered after this step are the
water/cement ratio and the amount of admixture/binder ratio.
After mixing the materials using a mixer, workability tests were
then carried out in order to verify the self-compactibility of the SCC.
Based on the flow test performed, it was verified that the mixture
was not fluid enough, presenting a flow result of 450 mm. From that
result, superplasticizer admixture was added so as to reach better
workability in the mixture, even before other tests were carried out.
No water was added to the mixture.
After increasing the amount of admixture in the mixture, new
Table 1 – proportions obteined in each determination method
PARAMETER
METHODS
Tutikian
Nan Su et al.
Repette-Melo
1:m
3
4
5
6
4,28
3,50
3,97
4,32
w/c (kg/kg)
0,35
0,47
0,56
0,68
0,50
0,39
0,48
0,56
a
(%)
64
62
60
59
67
61
60
59
C (kg/m³)
538
421
350
297
393
490
432
398
TAF (%)
20
20
20
20
18
10
10
10
TG (%)
48
48
48
48
40
50
50
50
Adt (%)
0,62
0,62
0,62
0,62
0,85
0,75
0,75
0,75
R$
313,04
252,53
215,86
188,08
249,25
298,97
267,14
248,49
Where
1:m = Unit trace for each family
a/c = Water / cement ratio (kg/kg)
α
= Content of mortar (%)
C = Cement consuption (kg/m³)
TAF = Content of fine sand aggregate in relation of total weight in mass (%)
TG = Content of gravel aggregate in relation of total weight in mass (%)
Adt = Content of additive (%) in relation of cement weight
$ = Total cost to obtein a 1m³ of concrete
Figure 2 – Flowchart of the
Repette-Melo [2] method